review of nanotechnology for soil and groundwater ... · review of nanotechnology for soil and...

Review of Nanotechnology for Soil and GroundwaterRemediation: Brazilian Perspectives

Antônio Thomé & Krishna R. Reddy &

Cleomar Reginatto & Iziquiel Cecchin

Received: 2 August 2014 /Accepted: 20 November 2014# Springer International Publishing Switzerland 2015

Abstract The soil remediation field is still in de-velopment in Brazil. Currently, it is not knownhow many contaminated sites exist across thecountry; however, due to the country’s large sizeand its extensive urbanization and industrialization,it can be postulated that the number of contami-nated sites must be very high. To remediate thesesites, new sustainable technologies should be iden-tified and evaluated. A technology that was bornin the 1990s in the USA, and has been fairlyinvestigated, is the use of nanoparticles (NPs) to

degrade contaminants in soils and groundwater.This study aims to present a bibliographic reviewof nanotechnology application to remediation ofsoils and groundwater, as well as assess the po-tential of conducting research in this field inBrazil. This paper first presents an overview ofthe number of contaminated areas identified inthe USA and Europe. The basic concepts ofnanomaterials followed by classification, synthesis,and characterization of nanomaterials are ex-plained. The main types of contaminants for whichthe technique was already applied as well as thechemical reactions between them and NPs are pre-sented. The issues related to delivery and migra-tion of NPs in the porous media is discussed.Concerns regarding the toxicity of nanomaterialsare discussed. The in situ applications ofnanomaterials for contaminated site remediationare presented. It is concluded that the issues in-volving remediation of soils and groundwater aresite specific and it is not possible to directlytransfer knowledge gained from sedimentary soils oftemperate climates for residual soils found in tropicaland subtropical climate regions. The research on nano-technology for site remediation in Brazil has just begun,and more efforts are required from the technical andacademic professionals to develop nanotechnology aspractical technology for the remediation of contaminat-ed sites.

Keywords Nanoparticles . Pollutant .Migration .

Toxicity . Soil . Remediation

Water Air Soil Pollut (2015) 226:121 DOI 10.1007/s11270-014-2243-z

A. Thomé (*)Graduation Program of Civil and Environmental Engineering,University of Passo Fundo, BR 285, km 292, Campus I, PassoFundo, RS 99001-970, Brazile-mail: [email protected]

A. ThoméUniversity of Illinois at Chicago, Chicago, IL, USA

K. R. ReddyDepartment of Civil and Materials Engineering, University ofIllinois at Chicago, 842 West Taylor Street, Chicago, IL60607, USAe-mail: [email protected]

C. Reginatto : I. CecchinEnvironmental Engineering Undergraduate Course,University of Passo Fundo, BR 285, km 292, Campus I, PassoFundo, RS 99001-970, Brazil

C. Reginattoe-mail: [email protected]

I. Cecchine-mail: [email protected]

1 Introduction

Soils and groundwater are contaminated by toxic pol-lutants from either natural or anthropogenic sources atconcentrations capable of posing great risk to humanhealth and the environment. The problems of contami-nated soils have raised great concern among environ-mental agencies due to the existence of a large numberof polluted sites, mainly in urban and industrializedareas (Hu et al. 2006).

In the USA, it is estimated that there are approxi-mately 350,000 contaminated areas, and that it will takemore than 30 years to achieve the remediation of thesesites. Investments needed to remediate these sites areestimated to be approximately 8.3 billion dollars/year(USEPA 2004).

In Europe, more than 342 thousand contaminatedareas have been identified, and it is estimated that thereare approximately 2.5 million potentially contaminatedsites. For decontamination of the sites which have al-ready been identified, the estimated cost is around 6billion Euros/year (Panagos et al. 2013).

The total number of contaminated sites in Brazil iscurrently unknown, but efforts are being made by envi-ronmental agencies to collect this information. In May2002, the Environmental Agency of São Paulo State(CETESB) for the first time released a list of its con-taminated sites, registering the existence of only 255contaminated areas. However, this record is being con-stantly updated, and in 2013 the number of contaminat-ed sites in São Paulo State rose to 4771 (CETESB2013). With the promulgation of the new law whichprovides criteria and guiding values of soil quality withrespect to the presence of chemical substances as well asguidelines for the environmental management of con-taminated sites due to anthropogenic activities, it isincreasingly being recognized as an important task toidentify, characterize and remediate contaminated sitesin Brazil. Due to the country’s large size and its recentextensive urbanization and industrialization, the numberof existing contaminated sites in Brazil is believed to besignificantly higher than that currently reported. TheUSEPA (2004) has recognized that the high cost ofremediation encourages the development and imple-mentation of new materials and technologies, whichcan result in faster, economical, and effectiveremediation.

There are many available technologies for the reme-diation of contaminated soils and groundwater, which

can be classified into: (1) ex situ technologies, in whichthe contaminated soils or groundwater (or both) must beremoved from the site and treated on-site or off-site, and(2) in situ technologies, in which the contaminated soilsor groundwater (or both) are treated directly within thesubsurface (Sharma and Reddy 2004). The use of in situtreatment technologies is often preferred because of themajor technical and economic advantages over ex situtechnologies (Karn et al. 2011; Reddy 2013).

Technologies that utilize NPs for remediation of con-taminated sites have been rapidly developed in recentyears, mainly in North America and Europe (USEPA2012; NANOREM 2013). The majority of these studiesare being carried out on bench scale. However, a fewstudies have reported the use of NPs at field scale (Karnet al. 2011; Mueller et al. 2012).

This paper aims to present a bibliographic review,providing the state-of-the-art on the use of nanotechnol-ogy for contaminated soil and groundwater remediation.It describes the main types of nanomaterials (NMs),contaminants that can be treated using NMs, reactivityof NPs, use of stabilizers to enhance transport/deliveryof NMs in porous media, toxicity of NMs, in situ appli-cations of NMs, and finally a discussion on the oppor-tunities for research and application of nanotechnologyto remediate contaminated sites in Brazil.

2 Nanomaterials

A nanometer (nm) is a billion part of meter, i.e., 10−9 m.Nanomaterials are materials with a dimension of 100 nmor less in at least one dimension, and nanoparticles arethose that have at least two dimensions between 1 and100 nm. Due to the presence of a large proportion ofatoms on the surfaces of NPs, they allow significantlyhigher numbers of adsorption/reactions with the sur-rounding contaminants. This characteristic makes NPsmore reactive than those materials with the same com-position in macro-scale. Either a sheet of paper that is100,000 nm thick or a strand of human hair that hasdimensions about 1,000 times higher than an NP(USEPA 2007) can be used as examples in order to geta better physical sense of the size of these nanomaterials.

The NMs can be classified as occurring naturally,accidentally, or deliberately manufactured in the labora-tory. Examples of naturally occurring NMs include clay,organic matter, and iron oxide; all of which are part ofthe soil composition. The accidental NMs are those

121 of 20 Water Air Soil Pollut (2015) 226:121

generated through air emissions, solid or liquid wastesfrom production facilities for nanoscale materials, agri-cultural operations, fuel burning, and weathering(Klaine et al. 2008). The nanomaterials manufacturedare either synthesized or developed with features aimedat improving their application in a technological orindustrial purpose.

The NMs can be produced in a variety of ways, andthey are grouped mainly into two technologies. The firsttechnology is from top to bottom or from outside toinside (top down), where part of something bigger (bulkmaterial) is turning into something smaller. The secondis a technology called bottom to top (bottom-up), wheresmall things will build something bigger (Niemeyer2001). Most top-down technologies involve methodssuch as milling, friction, heating, and photolithography(Cao 2004). Bottom-up technologies involve molecularcomponents such as raw materials connected withchemical reactions, nucleation, and growth process topromote the formation of more complex clusters (Cao2004; Rotello 2004). The NMs manufactured are de-signed with specific properties and can enter the envi-ronment through industrial or environmental applica-tions, such as their use for remediation of soils andgroundwater for example (USDHHS 2006; USEPA2007). Figure 1 presents the classification of the NMson the basis of their physico-chemical properties(Peralta-Videa et al. 2011).

The NMs differ according to the physico-chemicalcomposition, and they can be classified as organic or

inorganic. Organic NMs are composedmostly of carbonatoms, and can present in the form of spheres, ellipsoids,or hollow tubes. The formation of hollow spheres andellipsoids are called fullerenes, while the hollow tubesare called nanotubes that could have single or multiplewalls. The inorganic NMs are classified as quantumdots, metal, and metal oxide. The quantum dots aremixtures of two chemical elements with a size up to10 nm and are considered semi-conductors (e.g., CdS,CdSe, and CdTe). The metals can be present in the formof oxides of metals (zinc oxide, iron oxide, etc.), in theirpure form (nanogold, nanosilver, nanoirono), or bime-tallic. The bimetallic metals consist of a corrosive metal,such as iron (Fe) and zinc (Zn), along with noble metal,such as palladium (Pd), platinum (Pt), nickel (Ni), silver(Ag), and copper (Cu) (Ju-Nam and Lead 2008; Braret al. 2010; Fahlman 2011; O’Carroll et al. 2013).

3 Nanoparticles for Soil and GroundwaterRemediation

The use of NPs for decontamination of waters began inthe 1990s; therefore, it is considered a new technologyand its development is still in progress. Gillham (1996)was the first researcher to present the idea of using zerovalence iron in permeable reactive barriers (PRB), basedon his experience with the use of zero valence iron ondecontamination of waters containing contaminants ofthe halogenated group (Gillham and O’Hannesin 1994).

Manufactured Nanomaterials

Organics Inorganics

Fullerene Metal Oxide Metal Carbon Nanotubes Quantum Dots Metals

C60 Multi-Walled

C70 Single-Walled ZnO2

Fe2O3

AuAg CdSe

Fig. 1 Classification of nanomaterials according to physical–chemical properties

Water Air Soil Pollut (2015) 226:121 of 20 121

However, Wang and Zang (1997) and Zang et al. (1998)were the first to present research using NPs for decon-tamination of groundwater contaminated with organo-chlorines. In their research, synthesized bimetallic NPs(Pd/Fe, Pd, Pt/Fe/Zn, Ni/Fe) were tested in the labora-tory bench-scale tests for remediation of several aromat-ic chlorinated and some organ chlorine pollutants inwater. They observed a rapid and complete degradationof the pollutants with the use of NPs. For the first time, itwas proven that the elements Fe and Zn served primarilyas electron donors, while the Pd, Ni, and Pt as metalcatalysts. Also, it was first observed that the reactivity ofzero-valent nanoscale iron particles (zNIP) was 100times higher than zero valent iron in the macro-scaleform. Another important conclusion that was found wasthat no by-products were formed when zNIP degradedorganochlorine, similar to that reported where iron inmacroscale form was used. Finally, they concluded thatNPs offered great opportunity for research andtechnological application.

Ponder et al. (2000) were the first to report the use ofonly the zNIP for decontamination of groundwater con-taining metal chromium (Cr VI) and lead (Pb II). Theresearchers found that the use of zNIP quickly convertedthe Cr (VI) to Cr (III) and Pb (II) to Pb (0). Theyconcluded that this NP was suitable for use in situremediation applications.

Since 1997, many nanoscale materials have beenresearched for remediation, such as zeolites, nanometaloxides, nanotubes and carbon fiber, enzymes, and bime-tallic nanoparticles (Elliott and Zhang 2001; Schricket al. 2002; He and Zhao 2005; Yoo et al. 2007; Barneset al. 2010; Sakulchaicharoen et al. 2010). However, theapplication of zNIP received greater attention for theremediation of contaminated soils and groundwater.Over 90 % of the studies dealing with NPs for siteremediation used zNIP (Yan et al. 2013), mainly dueto their low toxicity and low cost of production inrelation to other NPs. Several review articles have beenpublished on the use of nNIP in remediation of contam-inated soils and groundwater during the last decade, andthese review articles cite over400 studies that have beenpublished over the past 16 years addressing variousaspects of using NPs for remediation of soils andgroundwater. The major review articles include: Zhang(2003), Tratnyek and Johnson (2006), Ju-Man and Lead(2008), Cundy et al. (2008), Reddy (2010), Karn et al.(2011), Kharisov et al. (2012), Crane and Scott (2012),Mueller et al. (2012), O’Carroll et al. (2013), Tang and

Lo (2013), Yan et al. (2013), Fu et al. (2014), and Toscoet al. (2014). These large numbers of publications dem-onstrate that, despite being a recent technology, mucheffort has been devoted to understand the behavior andapplication of zNIP with different contaminants in dif-ferent soils and groundwater conditions.

3.1 Nanoparticles Synthesis

Several methods have been developed for the produc-tion of NPs, including chemical vapor deposition, inertgas condensation, laser ablation, ignition load genera-tion, gas-aggregation spraying, thermal decomposition,thermal reduction of oxide compounds, metal complexhydrogenation, and reduction of aqueous iron salts(Crane and Scott 2012). Wang and Zang (1997) werethe first to synthesize zNIP by the aqueous-phase reduc-tion technique of Fe2+ using hydrated sodium boron.However, this form of production is only feasible for useon a laboratory scale, considering the high cost (over$200/kg of nFeZ) and the large amount of effluent withthe presence of boron produced. Using this method onan industrial scale33 is unlikely. Obtaining the zNIP byreducing the penta carbonyl iron (Fe(CO)5) in argon, inNH3, and organic solvents was also proposed (Choiet al. 2001; Kim et al. 2003; Karlsson et al. 2005), butdue to the high toxicity of Fe(CH)5 this method is alsonot a viable technique (Yan et al. 2013).

The production on an industrial scale using thebottom-up technology for obtaining the zNIP is accom-plished by reducing the goethite (α-FeOOH) or hematite(α-Fe2O3) by H2 at high temperatures, or by the use offerrous electrolysis (Capek 2004; Nurmi et al. 2005; Liuet al. 2012). Chun et al. (2010) reported that in somecases, a second metal can be precipitated or co-precipitated on the surface of the particle of zNIP. Thistechnique is used to add a catalyst and improve thecolloidal stability of the zNIP (Hosseini and Tosco2013). Obtaining zNIP from the use of polyphenolicderivatives of tea leaves and sorghum bran extracts havebeen studied in recent years (Hoag et al. 2009; Njagiet al. 2011; Chrysochoou et al. 2012; Machado et al.2013). Theoretically, these ecological reagents can beinjected directly into the soil to react with the irondissolved in groundwater that occurs naturally, or withiron that was added (Yan et al. 2013). This technique ispromising in soils with large amounts of iron, as is thecase of residual soils from Brazil. A purely physicalmethod of obtaining zNIP is the grinding of iron that


is in the bulk form. This technique was proposed by Liet al. (2009) and is known as one of the top downtechniques, but this method does not generate effluentsin manufacturing, and the zNIP obtained proved to beequally reactive with contaminants such as those obtain-ed by reduction techniques (Yan et al. 2013). However,some concerns exist on the durability of milling equip-ment and less control over the distribution of particlesize and morphology. A comprehensive review on all ofthese methods for synthesis of zNIP was presented byKharisov et al. (2012).

3.2 NanoparticlesCharacterization

The main characteristics of NPs that must be determinedare: morphology, particle size distribution, specific sur-face area, surface charge, and crystallographiccharacterization.

For determination of the morphology, imaging equip-ment is used, and the most common equipment used instudies of zNIP are the scanning electron microscopy(SEM) and transmission electron microscopy (TEM).Several studies showed the morphological characteris-tics of zNIP in the shape of spheres with a smoothsurface (Nurmi et al. 2005; Sun et al. 2007; Tiraferriet al. 2008; Darko-Kagya et al. 2010a, b; Tosco et al.2012; Eglal and Ramamurthy 2014). Yan et al. (2013)reported that this type of particle is more common inzNIP produced by bottom-up technology (e.g., chemicalreduction using boron hydrate). When the particles areobtained from the reduction of goethite and hematite forH2, they are more angular (Nurmi et al. 2005). Craneand Scott (2012) presented the morphology of severalzNIPs synthesized in different ways and from differentcommercial suppliers, showing the predominance ofspherical particles. As the zNIP is quite reactive withoxygen, a crust of iron oxide (Fe2O4) is formed aroundthe particle (Fig. 2a). A scanning electron microscopeimage of NIP synthesized by TODA Company Inc. ispresented in Fig. 2b (Reddy 2010).

The size distribution of nanoparticles can be obtainedthrough techniques of TEM analyzing the histogram ofgrain size distribution. The values observed by thistechnique ranged from 10 to 100 nm (Sun et al. 2006,2007; Phenrat et al. 2008; Machado et al. 2013; Eglaland Ramamurthy 2014). It is suggested that when study-ing the migration or transport of NIP in porous media, itis important to measure the hydrodynamic radiusthrough the techniques of acoustic spectrometry (AE)

or dynamic light scattering (DLS), considering that thepotential for NPs to aggregate and significantly influ-ence the migration process (Yan et al. 2013).

For the determination of the specific surface area(SSA) of NPs, Brunauer–Emmett–Teller (BET) andthe gas adsorption isotherms method has been common-ly used. Crane and Scott (2012) presented data fromSSA calculated geometrically from the density of thematerial and the diameter of the NP. In this calculation,the researchers took into consideration that the NPs werecompletely dispersed without taking into account thepossible changes of SSA due to agglomeration/aggre-gation. The specific surface area values for zNIP foundto vary from 10 to 50 m2/g (Nurmi et al. 2005; Sun et al.2006; Wang et al. 2010). Data of SSA of nanoparticlesin oxide form were compiled by Hua et al. (2012) andthey reported high values of SSA up to 600 m2/g fornano- amorphous iron oxide (γFe2O3).

The surface charge or zeta potential is measuredthrough the technique of electrophoretic mobility. Thetechnique consists of inserting a colloidal suspensiondiluted in a tube with two electrodes, and applying anelectrical potential to the suspension. It is possible toobtain the pH in the isometric point of charge (zero pointof charge, ZPC), which is found to range from 6.5 to 8.3for the zNIP (Kanel et al. 2005; Saleh et al. 2007;Tiraferri et al. 2008; Yan et al. 2013).

The crystallography of NPs is usually obtained byelectron diffraction (ED) and x-ray diffraction (XRD)techniques. However, the synthesis procedure used toproduce NPs influence their crystallographic properties(Yan et al. 2013). Studies showed that the main com-pound found has a core of polycrystalline Fe (0) and acrust of Fe3O4 (Nurmi et al. 2005; Liu et al. 2005; Wanget al. 2010). Calvin et al. (2003) and Yan et al. (2012)presented data from x-ray crystallography with the tech-nique of x-ray absorption spectra, and concluded thatonly with this analysis it is possible to observe someamorphous iron settings which are not observed by x-ray diffraction techniques. They highlighted that theamorphous portion is important to explain the highreactivity of NPs.

4 Contaminants Treated with Nanoparticles

Although there are many types of NPs that can be usedfor the decontamination of soils and groundwater, al-most all researchers consider using only zNIP for field


applications practical. It is also interesting to note thatmost studies primarily deal with decontamination ofsaturated soils and/or groundwater. Only a few studieshave addressed the remediation of contaminated soils inthe vadose zone (Shen et al. 2011).

Since the work published by Wang and Zang (1997)using bimetallic nanoparticles to decontaminate waterwith chlorinated solvents, many studies were performedusing a wide variety of organic and inorganiccontaminants. An assessment study performed by Yanet al. (2013) (based on 445 publications) showed that themain types of contaminants that were treated with zNIPwere: halogenated aliphatics (26.9 %), halogenated ar-omatic hydrocarbons (17.8 %), other organic compo-nents (17.8 %), metals (25.8 %), and non-metals, inor-ganic (11.7 %). Therefore, the treatment of organiccontaminants predominated, accounting for 62.5 % ofthe total studies. Inorganic contaminants correspond to37.5 %, with emphasis on metallic contaminants thathave beenmost studied in this category. Table 1 presentsexamples of contaminants that were treated with NPs invarious published studies.

5 Reactivity of Nanoparticles with Contaminants

Based on the chemical reaction involved, remedi-ation technologies that use NPs can be dividedinto two groups (Cundy et al. 2008): (a) reductivetechnologies that use NPs as an electron donor totransform or convert the contaminant in a lesstoxic and less mobile environment, and (b) stabi-lization and sorption technologies which use theNPs as an agent of sorbent, precipitant, andco-precipitant of the contaminant.

The chemical reaction of reduction using zNIPisoften targeted for the remediation of soils and ground-water. In general, zNIP in aqueous media is susceptibleto corrosion, being transformed rapidly into Fe2+ andmore gradually to Fe3 +. In waters with the presence ofdissolved oxygen (DO), Fe(0) uses this element as anoxidant (Eq. 1). Following the reaction, it can turn intoFe3+ (Eq. 2), precipitating as a compound less soluble,i.e., the iron hydroxide. The reactions can also occur inanaerobic environments. So in this case, the oxygenfrom the water is used as an oxidant, producing hydro-gen on molecular form (Eq. 3) (Kharisov et al. 2012).

2 Fe sð Þ þ O2 aqð Þ þ 4Hþaqð Þ → 2 Fe2þ aqð Þ þ 2H2O lð Þ

ð1Þ

4Fe2þ aqð Þ þ 4Hþaqð Þ þ O2 aqð Þ → 4Fe3þ aqð Þ þ 2H2O lð Þ

ð2Þ

Fe 0ð Þsð Þ þ 2H2O lð Þ → Fe2þ aqð Þ þ H2 gð Þ þ 2OH− ð3Þ

The reaction of metallic iron Fe(0) to the Fe2+ dis-solved in water has a standard potential E0 of -440 mV,indicating that the Fe(0) has great capacity for reducingcontaminants. The most common processes of organiccontaminants degradation by Fe(0) are hydrogenolysisand dehalogenation (Li and Farrell 2000; Arnold andRoberts 2000).

The hydrogenolysis of chlorinated compounds suchas trichloroethene (TCE) involves the replacement of achlorine atom by hydrogen atom, requiring both anelectron donor and a proton donor (hydrogen). Thegeneral equation of chlorinated compounds reduction

70nm

Fe3O4

Fe0

Fig. 2 NIP synthesized by TODA Company Inc.: a schematic structure (b) and photomicrograph from MEV (source: Reddy)


is presented in equation (Matheson and Tratnyek 1994;Orth and Gillham 1996).

ClHC ¼ CCl2 þ 2e− þ Hþ → ClHC ¼ CHCl þ Cl−

ð4Þ

The dehalogenation involves a reductive process ofchlorine atoms without the addition of hydrogen, butwith the formation of a new C–C bond, which may beconnected with one carbon neighbor and is called βreaction. Also, the reaction can occur with the samecarbon, called α reaction. These dehalogenation reac-tions are presented in Eqs. 5 and 6, respectively(Matheson and Tratnyek 1994).

Reactionβ : ClHC ¼ CCl2 þ 2e− → HC ≡ CCl þ 2Cl−

ð5Þ

Reaction α : Cl2C ¼ CH2 þ 2e− → H2C ¼ C : þ 2Cl−

ð6Þ

It has been reported that the dehalogenation reactionkinetics is favorable than hydrogenolysis for contami-nated site remediation applications, because of potentialfor formation of more harmful intermediate by-productsthan the source contaminant with hydrogenolysis. Forexample, the trichloroethene (TCE) when reduced byhydrogenolysis forms the following compounds: cis-dichloroethene (cDCE), vinyl chloride (VC), and eth-ane. cDCE and VC are known to be more toxic thanTCE. On the other hand, when the TCE is reduced byreaction of β-dehalogenation, it forms the chlorine acet-ylene and acetylene; both are very unstable compoundsthat are quickly degraded. Some studies with zNIP havereported the prevalence of β dehalogenation reaction,with no formation of the vinyl chloride, making this type

Table 1 Contaminants that have already been treated with nanoparticles in previous investigations

Contaminant Bibliographic reference

Organics

Chlorinated solvents Wang and Zhang (1997), Lien and Zhang (1999), Choe et al. (2001),Schrick et al. (2002)a, Nutt et al. (2005)a, Liu et al. (2005), Sarathyet al. (2010)a, Barnes et al. (2010)a

Organophosphorus Ambashta et al. (2011), Almeelbi and Bezbaruah (2012)

p-chlorophenol Cheng et al. (2007), Reddy et al. (2012).

Diphenyl-polybrominatedbiphenyl ethers Li et al. (2007), Shih and Tai (2010)

Biphenyl-biphenyl Wang and Zhang (1997)a, Varanasi et al. (2007), Liu and Zhang (2010),

Others organics

Antibiotcs Ghauch et al. (2009), Fang et al. (2011)

Azo-dyes Lin et al. (2008), Fan et al. (2009)

Pesticidas clorados Joo and Zhao (2008), Satapanajaru et al. (2008), Elliot et al. (2008),Tian et al. (2009),

Nitroaromáticos e nitroamines Choe et al. (2001), Naja et al. (2008), Zhang et al. (2009, 2010), Darko-Kagya et al. (2010a, b), Reddy et al. (2011)

Metals

Alkaline earth metals: bario and berilio transition metals:chrome; cobalt; copper; lead; molybdenum; nickel; silver;technetium; vanadium; zinc and cadmium nonmetals: arsenioand selenium; actininóides: uranium and plutonium

Ponder et al. (2001), Kanel et al. (2005), Kanel et al. (2006), Burghardtet al. (2007), Celebi et al. (2007), Darab et al. (2007), Kanel et al.(2007), Li and Zhang (2007), Xu and Zhao (2007), Karabelli et al.(2008), Riba et al. (2008), Üzüm et al. (2008), Dickinson and Scott(2010), Olegario et al. (2010), Scott et al. (2011), Klimkova et al.(2011),

Inorganics anions

Nitrate, perchlorate, and bromate Choe et al. (2000); Wang et al. (2006); Xiong et al. (2007); Scott et al.(2011); Hwang et al. (2011);

a It did not use the zNIP or zNIP was used with other metal (NP bimetallic)


of remediation advantageous as compared to biologicalprocesses where the hydrogenolysis is the predominantreaction (Carucci et al. 2007).

zNIPs reacts with oxygen and form a thin layer ofiron oxide around the particle. Therefore, every particleof zNIP is formed by a nucleus of Fe(0) with an oxidecrust (Fig. 2a), with a thickness of approximately 2 to3 nm (Martin et al. 2008; Wang et al. 2009). Whenapplied in field, the reaction of NPs slowly decreasesas the crust thickness increases. Sometimes this crust isformed by iron hydroxide (FeOOH) (Baer et al. 2010).However, this thin crust layer still allows the transfer ofelectrons from the metal core, allowing the NP to keepits capacity of reduction. Also, because a NP has a crustof oxide, it has the ability to react with inorganic com-ponents such as metallic anions and metal. Weber(1996) reported that even the organic contaminants ini-tially adsorbed to zNIP and then undergo the process ofreduction and carbon chain breakage.

The reaction with inorganic contaminants is con-trolled by redox potential of the inorganic species. Ifthe contaminant has a redox potential greater than theFe(0), the component is removed by reduction and thenby precipitation and co-precipitation. If the redox poten-tial is smaller than the Fe(0), the reduction will not bepossible, and the contaminant can only adsorbed by theNPs. However, there can be situations in which thereduction and co-precipitation occur at the same time.Table 2 presents the predominant reaction mechanismsthat will occur in the presence of the most commoninorganic contaminants (O’Carroll et al. 2013).

The addition of a small amount of a second metal onthe surface of zNIP, also called doping, causes a signif-icant increase in the reactivity, since this second metalacts as catalyst. Among many transition metals studiedfor catalytic dehalogenation, palladium (Pd) is the mostcommonly used. This metal has chemical and structural

properties ideal for generating hydrogen species oncethe reaction starts, and becomes easier for breaking thechain of carbon-halogen (Alonso et al. 2002;Wong et al.2009). However, the addition of this second metal (bi-metallic species) makes the process more harmful to theenvironment, and has been used sparsely in practicalapplications. Yan et al. (2013) reported that the additionof the second metal causes reactions to occur faster,accelerating the process of the oxidation of zNIP. Thus,the NP becomes inactive in a shorter period of time. Thisphenomenon has a great influence on zNIP transport inporous medium, because the effectiveness of the zNIPwill be reduced in relation to distance, demanding morezNIP injection locations in the field.

All the reactions that occur with NPs are stronglyinfluenced by a large number of factors, which dependon the particle, contaminant, and study site characteris-tics. Thus, the results from laboratory studies cannot bedirectly transferred to the field scale. The pilot-scalestudies are currently still required in order to obtain theactual reactive behavior between NP and the contami-nant. Kharisov et al. (2012), O’Carroll et al. (2013), Yanet al. (2013), and Fu et al. (2014) provide more detailson zNIP reactivity with contaminants.

5.1 Use of Stabilizers (Coatings)

The zNIP are subjected to high Van der Waals forces,and they also possess high magnetic properties and aresubjected to magnetic forces; all of these factors causeNPs to agglomerate, significantly reducing the specificsurface. In addition, the particles become denser thanwater and settle down quickly in solutions (Reddy2010). These properties make it difficult for the NPs totravel required distances in soils and groundwater,necessitating the installation of a larger number ofinjection points across the contaminated area, whichmakes the remediation technique expensive. Yan et al.(2013) present the difficulty of preparing zNIP stablesuspensions and dispersing/delivering them into con-taminated subsurface zones.

The main strategy that has been adopted to increasethe zNIP stability and dispersion in subsurface is tomodify their surface characteristics. The surface modi-fication may reduce their reactivity, but cause the dis-persion of the particles to allow them to be delivered intothe contaminated zones under in situ applications. Themost common form of surface modification is to add astabilizer to the NPs (Schrick et al. 2004). The stabilizer

Table 2 Predominant reaction in the most common inorganiccontaminants

Predominant reactions Inorganic contaminant

Reduction Cr, As, Cu, U, Pb, Ni, Se, Co, Pd, Pt,Hg, Ag

Adsorption Cr, As, U, Pb, Ni, Se, Co, Cd, Zn, Ba

Oxidation/re-oxidation As, U, Se, Pb

Co-precipitation Cr, As, Ni, Se

Precipitation Cu, Pb, Cd, Co, Zn


can be added during the synthesis of the zNIP, calledpre-synthesis (He and Zhao 2007; Barnett et al. 2011;Sakulchaicharoen et al. 2010), or during the dilution,called the post-synthesis (Saleh et al. 2005; Tiraferriet al. 2008; Cirtiu et al. 2011; Cameselle et al. 2013).The post-synthesis method has been shown to be effec-tive for reduced reactivity of NPs (Phenrat et al. 2009)while the pre-synthesis method may help disperse theparticles, increasing the NP specific area and conse-quently, their reactivity (He and Zhao 2005). It is pref-erable to use stabilizers with a negative charge becauseits reactivity with soil particles (usually negativelycharged) is repulsive, which reduces the agglomerationof the particles (Petosa et al. 2010). The stabilizer mustalso have easy degradability features with low (or no)toxidade (Kirschling et al. 2010; Batley et al. 2013). Inother words, the stabilizer must be environmentallyfriendly in order to avoid the idea that its use is aproblem rather than a solution.

The synthetic polymers were the first to be investi-gated as stabilizers (Saleh et al. 2005). Usually they areadded in very low concentrations, such as a few milli-grams per liter. There are several types of polymersdescribed in the literature, among them are: polyacrylicacid (Schrick et al. 2004;Wei et al. 2010; Jiemvarangkulet al. 2011; Cameselle et al. 2013), polystyrene sulfonate(Phenrat et al. 2008, 2009), polyaspartate (Phenrat et al.2009), and the blends of different polyelectrolytes(Hydutsky et al. 2007; Sun et al. 2007; Sirk et al.2009). In addition to studying some polymers (poly-acrylic acid and aspartic acid), Cameselle et al. (2013)also evaluated the use of aluminum lactate, sodiumlactate, and ethyl lactate, as well as differentcompositions of cyclodextrin. They found that thesecompounds are suitable for use as dispersants, and thebest result was obtained by aluminum lactate. Yan et al.(2013) presented the polyacrilic acid and polystyrenesulfonate polymers as more attractive for applicationdue to their high molecular weight and high density offunctional groups present in the molecule.

Tosco et al. (2014) described the use of natural poly-mers (biopolymers) which has gained considerable in-terest from researchers due to high availability, lowcommercial value, and low harmfulness to the environ-ment. Several studies are reported on the use of differentbiopolymers: guar gum (Tiraferri et al. 2008;Velimirovic et al. 2012; Gastone et al. 2014), xanthangum (Dalla Vecchia et al. 2009; Comba and Sethi 2009),calcium alginate (Bezbaruah et al. 2009), starch (Dong

and Lo 2013), carboxymethyl-cellulose (He and Zhao2007; Kanel et al. 2008; He et al. 2010; Bennett et al.2010; Krol et al. 2013), and extract of sineguelas(Arshad et al. 2014).

An alternative proposal to stabilize the zNIP for usewith contaminants denser than water (DNAPL) was byadding it into water–oil emulsions. The blend of surfac-tant and biodegradable oils (such as soybean oil andcorn oil) is used. The technique consists of encapsulat-ing zNIP in oil, and not allowing its interaction withgroundwater. This allows it, wrapped in a bubble of oil,to reach greater depths without reacting. Field studieswhere the technique was applied have showed goodresult (Quinn et al. 2005; Berge and Ramsburg 2009,2010).

Another way to increase the stability of the NPs is bysupporting them on a solid substrate. The main sub-strates studied include: silica (Zhang et al. 2013), car-bons (Zhu et al. 2009; Ling et al. 2012), resinas (Shuet al. 2010; Jiang et al. 2011), bentonite (Shi et al. 2011),kaolinite (Zhang et al. 2011), and zeolite (Kim et al.2013). These studies were all conducted in bench scale,requiring field studies to assess their efficiencies. Yanet al. (2013) reported that it is necessary to produce thesesupported NPs on a large scale at low cost.

6 Transport of Nanoparticles in Porous Media

Several studies have been conducted to understand howthe NPs react with the contaminants and migrate(transport) in porous media using column experimentsin the laboratory. These experiments are important toassess the interaction of the contaminant with the NPsand to better understand the mobility of the NPs.However, there is insufficient data obtained in field scalethat systematically evaluates the NPs transport, consid-ering all the complex variables involved (Tosco et al.2014).

Column experiments performed with zNIP withoutbeing stabilized showed little mobility in the porousmedium (a few centimeters). Therefore, they are noteffective for applications without the use of a stabilizer(Schrick et al. 2004; Tiraferri and Sethi 2009; Johnsonet al. 2009; Reddy et al. 2014). The low mobility ofthese particles was attributed to formation of aggregatesand mechanical filtration of the NPs (Saleh et al. 2007).The transport of NPs can also be prevented by hydro-philic and hydrophobic interactions, the heterogeneity


of the environment, and by the chemical reactions of theNPs with the solid particles of the soils (Reddy 2010).

The use of stabilizers with zNIP proved to be effec-tive in several studies carried out in the column exper-iments. Particles that were not stabilized migrated a fewcentimeters in the porous medium, but with stabilizerthe zNIP were able to be transport across the entire soilcolumn and elute at the outlet (Saleh et al. 2007;Hydutsky et al. 2007; Tiraferri et al. 2008; Kanel et al.2008; Shih et al. 2009; He et al. 2009; Reddy et al. 2012,2014). Interesting to note that the presence of organicmatter naturally found in some soils caused reactionssimilar to stabilizers added to zNIP, increasing the mo-bility of the NPs (Johnson et al. 2009).

Great advances have been made in order to under-stand contaminant migration through column experi-ments, but many of these studies were conducted underconditions that do not represent the reality of the field.Primarily, issues related to flow velocity, where hydrau-lic gradients generally adopted higher than those used ininjections in the field. Another relevant fact is related tothe issue of the concentration of NPs, which in manystudies were adopted well below the actual need to reactwith the contaminant (O’Carroll et al. 2013). Reddy(2010) raised this issue and also pointed to the lack oftesting on the actual field soils in column experiments,as many evaluations were usually based on clean uni-formly graded sands or glass particles with little or noreactivity with the NPs. Also, the use of distilled wateror deionized water as a liquid conductor of NPs does notreproduce the reactions that occur with groundwater insitu. Therefore, NPs migration in porous media willdepend on variables such as the flow velocity, particlesize distribution, viscosity of the injected solution (con-centration), and reactivity with groundwater constitu-ents and soil particles.

Reddy et al. (2011) assessed the use of the electroki-netic technique to improve the migration of NPs inporous media with low permeability (clays).Laboratory experiments were conducted using the kao-lin as a porous medium percolated with zNIP stabilizedwith aluminum lactate. It was found that the use ofelectrokinetic improved the zNIP migration in low per-meability porous medium, and this technique can beused in remediation of these types of soils.

The mechanisms involved in colloid retention byporous medium are classified as only physical orphysico-chemical (Tosco et al. 2014). The process offiltration or particle retention is a predominant physical

process. The retention of individual NPs is unlikely asthe size of NPs is much smaller than the size of the poresthat allow the passage of liquid (Tosco and Sethi 2010).Although some researchers suggested sizes ofNPs torange from 100 to 200 nm in order to improve theprocess of mobility in typical groundwater velocitiesand reduce the filtration process by soil particles (Baiand Tien 1996; Elliott and Zhang 2001; Tufenkji andElimelech 2004). The mechanism of filtration is a me-chanical process related to the formation of aggregatesof NPs, which is an irreversible process.

The physico-chemical interactions between NPs andporous medium will result in dynamic depositions thatcan be reversible. This process is transient, i.e., varieswith time. At the beginning of the injection, only a fewNPs are deposited on the surface of the porous mediasolid particles, and have little interference in existingenergy between the NPs that are passing through.However, over time a greater number of particles willbe adhering to the soil particles, thus reducing the poresize which functions as filter, i.e., retaining NPs that arepassing through. At this stage, the influence on electro-chemical balance begins. At the end of the process, thisinteraction will eventually clog the pores, which couldreduce and in some cases even cease the flow throughthem. Therefore, the flow and the transport of NPs arecoupled problems (Tosco and Sethi 2010; Torkzabanet al. 2012). This is the main difference in the NPstransport mechanism in porous media in relation tocontaminant transport. In the case of transport of theNPs, the advection is influenced over time as a result ofchange in permeability due to clogging of pores, whichdoes not occur in general contaminant transportproblems.

The transport of NPs has been modeled using thefiltration theory of colloids proposed by Yao et al.(1971). This theory is incorporated into the equation ofadvection and dispersion of contaminant transport byincluding a third term that seeks to describe the physicaland chemical filtration which occurs in porous medium(Eq. 7) (Reddy et al. 2014).

R∂c∂t

¼ Dh∂2c∂2x

− Vp∂c∂xλC ð7Þ

Where C is the concentration of NPs, R is retardationcoefficient, t is time, Dh is the coefficient of dispersion,Vp is the velocity of the fluid, x is the flux length, and λis constant from the first-order that takes into account


the filtration, i.e., the reason as the NPs are attached ordeposited in the collector system. The value of λ iscalculated considering the cumulative effect of diffusion(considering the suspension with features of Newtonianfluid), interception, and the action of gravity on theparticles.

The filtration model was also used by various re-searchers with success for reproduction of column exper-imental results (Dalla Vecchia et al. 2009; He et al. 2009;Phenrat et al. 2010; Hosseini and Tosco 2013; Reddyet al. 2014). Some studies have used these results toestimate the distance to which the NPs would migratein actual situations (Yang et al. 2007; Kocur et al. 2013;Krol et al. 2013; O’Carrol 2014). However, the concen-trations of zNIP used in field applications are higher thanthat used in these studies, making the direct application ofthe results unreliable (Tosco et al. 2014). Changes to thefiltration model have been proposed, taking into accountissues related to the magnetic interaction between theNPs and non-Newtonian properties of the suspension(Hendren et al. 2013; O’Carroll et al. 2013).

Some other models were also applied to model thetransport of NPs. In the absence of clogging, i.e., whenthe concentration of NPs is very low, it was possible touse the models such as HYDRUS (Simunek et al. 2006),STANMOD (VanGenuchten et al. 2012), and MNM1D(Tosco and Sethi 2009; Tiraferri et al. 2011). The SEAWAT model, which takes into account the variation ofparticle density, was used to evaluate 2D transport ofNPs in sands (Kanel et al. 2008). Tosco and Sethi (2010)have proposed a new model called E-MNM1D, whichtakes into consideration the fluid visco-plastic propertiesand the progressive clogging of the pores.

There is a consensus among researchers that it isnecessary to expand the models to field-scale applica-tions. It is also necessary to address several issues thatare often not considered in modeling such as the reac-tions between the NPs, reactivity of NPs with the envi-ronment (soil and groundwater constituents), reactivityof NPs with pollutants, and the prediction of residualconcentration of NPs in the environment at the end ofthe process (Reddy 2010; O’Carroll et al. 2013;Hendren et al. 2013; Tosco et al. 2014).

7 Toxicity of Nanoparticles

The concept of deliberately injecting NPs into soils andgroundwater for remediation purposes has raised

questions and concerns about their toxicity and negativeimpacts to the environment, even though their beneficialeffect of destruction and transformation of toxic con-taminants is fully realized (Reijnders 2006; Nel et al.2006; Navarro et al. 2008; Posner 2009; Brar et al. 2010;Grieger et al. 2010, Batley et al. 2013). In the case ofzNIP, the same characteristics that make it an excellentmaterial for use in decontamination, such as small sizeand high-capacity of reduction and adsorption, alsomake them as a potential contaminant to the environ-ment (Peralta-Videa et al. 2011).

Some studies on the toxicity of zNIP on microorgan-isms were conducted in bench scale (Xia et al. 2006;Auffan et al. 2008; Lee et al. 2008; Diao and Yao 2009;Kirschling et al. 2010; Kim et al. 2010, 2011; Li et al.2010; Xiu et al. 2010; Sevcu et al. 2011). These studiesshowed that the zNIP has a high potential biocide whenused without stabilizer. However, after the zNIP be-comes oxidized, its influence on microorganisms isreversed, making them as an excellent stimulant ofmicrobiological activity by their oxidized iron bioavail-ability. This behavior is favorable to use in remediation,because at first the iron is used as a reductive, and afterits oxidation, it will assist in decontamination throughthe biostimulation (Tosco et al. 2014). It was also ob-served that the use of zNIP with organic stabilizersassists in the process of bioremediation as the stabilizercan act as a biostimulant. On the other hand, the con-centration of zNIP without a stabilizer for biocidal effectwas 5 mg/ldozNIP, while with zNIP stabilized concen-tration increased to 500 mg/l, i.e., 100 times higher (Liet al. 2010).

To date, there has been a field-scale study to assesstoxicity of NPs. Crane and Scott (2012) stated that zNIPinjection into groundwater may exhibit a lower toxicitythan that found in in vitro scale studies due to the rapidoxidation reactions that occur in field. The potential fortoxic effects of zNIPs injected into groundwater sourceis unlikely as they get oxidized quickly into fairly im-mobile oxides, eliminating any possibility of exposureto humans or other mammals. The exposure of zNIPs tohumans is more likely to occur during handling (contactwith skin) and inhalation prior to injection; however,such exposure can be easily prevented through the useof safety equipment.

Karn et al. (2011) reported that iron oxide is not toxicon its own, but it can carry harmful contaminants ad-hered to its surface. They cite an example of iron oxidewith copper acceded on its surface found several


kilometers away from a copper mine (Hochella et al.2005). Of course, this will depend on several factorsrelated to the porous media and groundwater. Kharisovet al. (2012) reinforces the hypothesis that the toxicity ofzNIP in environmental applications is not yet known.The advantages of application in the decontamination ofhighly harmful contaminants have been studied andproved the feasibility of using them effectively.Nevertheless, the toxicity and risks of using zNIP muststill be investigated with additional studies (Tosco et al.2014).

8 In Situ Applications

The first use of NPs for in situ remediation application isreported in 2001 (Elliot and Zhang 2001), few years afterthe first publication of a laboratory study suggesting theuse of zNIP for decontamination of groundwater (Wangand Zhang 1997). The first field study was performed bythe same research group that published the first lab work;thus, they injected a solution of bimetallic (Fe/Pd) nano-particles, at a concentration of 1 mg/L. The site wascontaminated predominantly with TCE (at a concentra-tion ranging from 445 to 800 μg/L), and other organo-chlorines. The researchers observed that despite havingseen a significant reduction in the concentration of thecontaminant at the point of application, the mobility ofthe Fe/Pa was reduced. The implementation ofunstabilized NPs resulted such low mobility, and theuse of stabilizers improves mobility in situ applications(Henn and Waddill 2006; Bennett et al. 2010; He et al.2010; Johnson et al. 2013; Kocur et al. 2014). Althoughsome studies have reported success with the use of thetechnique, there is still a challenge to be overcome aseven stabilized particles do not travel more than a fewmeters in groundwater (O’Carroll et al. 2013).

Karn et al. (2011) and Mueller et al. (2012) reviewedin situ applications of NPs in the USA and Europe,respectively. Details of the site locations can be foundon the web pages that discuss emerging nanotechnologyprojects (Kuiken 2010; USEPA 2014). They reported 58locations where the technology was used in the world sofar. Of these, 17 were in Europe, 1 in China, and theother sites were in North America (2 in Canada and 37in 12 American states). At these sites, the materialscontaining zNIP were used in 98 % of cases. Metalsoxides (Karn et al. 2011) were used in 2% of cases, usedmainly as sorbents for metal contaminants.

Regarding the contaminants found at these field sites,the more prevalent contaminants treated were theorganochlorides with emphasis on PCE, TCE, andPCB. At some sites, other contaminants were also re-ported, such as Cr, Ni, and nitrates. At a particularlocation (Hannover in Germany), the treatment of hy-drocarbons and aromatic hydrocarbons group (BTEX)was reported. Not all sites have published technicalefficiency, but those who provided these values rangedfrom 40 to 99 %, but mostly in the range above 90 %.The concentration of zNIP used ranged from a mini-mum of 1 g/L to a maximum of 30 g/L, with morefrequently used concentration values up to 10 g/L(Cook 2009; Bardos et al. 2011; Mueller et al. 2012;Yan et al. 2013; USEPA 2014).

In situ injection of NPs can be accomplished bydifferent methods, depending basically on the perme-ability of the porous media. At sites where the soils arepermeable and the contaminated area is smaller, NPscould be injected through wells installed within the siteor injected using direct push technologies at the selecteddepths. In both cases, the injection pressure is the col-umn of liquid in the system. For soils that have lowerpermeability, the injection pressures required will behigh, which may or may not induce soil fracture de-pending on the applied pressure (Christiansen et al.2010; Rosansky et al. 2013).

Standard procedures are not yet developed on the useof NPs for field remediation applications. The variablesinvolved in field applications include: the number ofinjection wells, the injection pressure, the distance ofeach well, the concentration of NPs, and the distanceand time of injection of the NPs. All of these factorsdepend on the site-specific conditions, and it is notpossible to generalize or standardize based on the pub-lished studies alone. It is recommended that laboratoryexperiments should be undertaken with the soil andgroundwater obtained from the site in order to assessvarious field design parameters for the project, and thena pilot-scale testing should be conducted to evaluate thefield scale-up issues. Based on such approach, it ispossible to validate in situ system designs based on thesmall-scale studies (Wei et al. 2010; Crane and Scott2012; Yan et al. 2013).

The cost of applying nanotechnology for remediationof soils and groundwater depends on several factors,such as cost of raw material, injection, and monitoring.The cost of the raw material (zNIP) has been reduceddue to an increase in production and the number of


suppliers. In 2004, reported costs were approximately$200.00/kg (Crane and Scott 2012). According to zNIPcompanies in the USA and Europe, it is determined thatthe average cost is around $60.00/kg (as of April 2014),showing significant reduction in the cost of zNIP.Injection and monitoring costs are specific to each site,depending on the complexity of the geology, the depthof the contaminant, the size of the area treated, and thetime needed for monitoring after implementing the re-mediation. In the 58 cases of in situ applications, a fewstudies reported the average price per unit volume treat-ed and it ranged from $130 to $320/m3 of contaminatedsoil (Cook 2009). Karn et al. (2011) reported that theapplication of nanotechnology for remediation of con-taminated groundwater in lieu of pump and treat tech-nique can reduce the cost of the treatment from 80 to90 %. In the USA alone, use of nanotechnology insteadof conventional technologies can reduce the remediationcost by approximately 90billion U.S. dollars over thenext 30 years.

9 Final Considerations and Research Opportunitiesin Brazil

This study provided a comprehensive review of theapplication of nanotechnology for the remediation ofcontaminated soils and groundwater. In Brazil, nano-technology is an emerging new field and to date nostudies have been published based on a comprehensiveliterature search of research theses and journalspublications.

Brazil, based on its large size and degree ofurbanization and industrialization, is believed tohave many contaminated sites that are not officiallypresented in the statistics of environmental agencies.It is believed that with the approval of the new lawon the subject, the number of contaminated sites inBrazil will increase considerably, requiring the needfor their remediation to protect public health and theenvironment.

Several published studies demonstrate that nanotech-nology to be effective for decontamination of a widerange of contaminants at a very competitive price.However, this technique is site specific, i.e., the resultsfor sedimentary soils in temperate climate regions (lo-cations such USA where technology is extensivelyresearched) cannot be applied to soils with unique char-acteristics such as soils found in tropical and subtropical

climate regions such as Brazil. It is evident that there is aneed to develop nanotechnology for remediation ofcontaminated soils and groundwater in Brazil.

Regarding the synthesis of NPs, there are alreadycompanies producing NPs which are both stabilizedand not stabilized. The challenge in Brazil is to produceNPs offering competitive pricing as compared to thatproduced in the international market. It is of great inter-est to investigate polyphenolic ecological reagents thatcan be injected directly into the soils and groundwater toreact with the iron present in residual soils and/or dis-solved in groundwater. However, the challenge isobtaining the extracts of other raw materials that existin different regions of the country. The development oforganic stabilizers for use in post-synthesis from low-cost products should be a priority for research anddevelopment.

The transport, reactivity, and toxicology of NPs inBrazilian residual soils should be investigated. It isnecessary to perform both fundamental laboratory stud-ies as well as field pilot-scale tests, before the imple-mentation at full-scale at actual field sites. Any initial insitu applications of nanotechnology require systematicand long-term monitoring to assess the effectiveness ofthe technology.

Overall, it can be concluded that the remediationtechnique using NPs is complex and is influenced byseveral bio-physic-chemical processes that occur depend-ing on the site-specific geologic, hydrogeological, andcontaminant conditions. But, the nanotechnology hasgreat promise to remediate different contaminants effec-tively, efficiently, and economically. Brazil needs to takeadvantage of the knowledge already acquired from pre-vious studies, and adapt to specific soil and climateconditions so that it will be possible to apply this tech-nology to remediate contaminated sites in the near future.

References

Academic Publishers, 249–274 Grieger, K. D., Fjordboge, A.,Hartmann, N. B., Eriksson, E., Bjerg P. L. & Baun, A.(2010). Environmental benefits and risks of zerovalent ironnanoparticles, (nZVI) for in-situ remediation: Risk mitigationor trade-off? Journal of Contaminant Hydrology, 118(3–4),165–183.

Almeelbi, T., & Bezbaruah, A. (2012). Aqueous phosphate re-moval using nanoscale zero-valent iron. Journal ofNanopartarticles Research, 14, 900. doi:10.1007/s11051-012-0900-y.


http://dx.doi.org/10.1007/s11051-012-0900-y

http://dx.doi.org/10.1007/s11051-012-0900-y

Alonso, F., Beletskaya, I. P. & Yus, M. (2002). Metal-mediatedreductive hydrodehalogenation of organic halides. ChemicalReview, 102(11), 4009–4091.

Ambashta, R. D., Repo, E. & Sillanpää, M. (2011). Degradation oftributyl phosphate using nanopowders of iron and iron-nickelunder influence of static magnetic field. IndustrialEngineering Chemical Research, 50(21), 11771–11777.

Arnold, W. A. & Roberts, A. L. (2000). Pathways and kinetics ofchlorinated ethylene and chlorinated acetylene reaction withFe(0) particles. Environmental Science Technology, 34(9),1794–1805.

Arshad, M., Soleymanzadeh, M., Salvacion, J. W. L. &SalimiVahid, F. (2014). Nanoscale zero-valent iron (NZVI)supported on sineguelas waste for Pb(II) removal from aque-ous solution: kinetics, thermodynamic and mechanism.Journal of Colloid and Interface Science, 426(15): 241–251.

Auffan, M., Achouak, W., Rose, J., Roncato, M.-A., Chaneac, C.,Waite, D. T., Masion, A., Woicik, J. C., Wiesner, M. R. &Bottero, J.-V. (2008). Relation between the redox state ofiron-based nanoparticles and their cytotoxicity towardEscherichia coli. Environmental Science Technology,42(17) 6730–6735.

Baer, D. R., Gaspar, D. J., Nachimuthu, P., Techane, S. D., &Castner, D. G. (2010). Application of surface chemical anal-ysis tools for characterization of nanoparticles. Analyticaland Bioanalytical Chemistry, 396(3), 983–1002.

Bai, R., & Tien, C. (1996). A new correlation for the initial filtercoefficient under unfavorable surface interactions. Journal ofColloid Interface Science, 179, 631–634.

Bardos, P., Bone, B.,Elliott, D., Hartog, N., John H. & Paul, N.(2011). A risk/benefit approach to the application of ironnanoparticles for the remediation of contaminated sites inthe environment. Defra Research Project Final Report.Avaliable in: http://randd.defra.gov. uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=0&ProjectID=17502. Acessed in May 29 2014.

Barnes, R. J., Riba, O., Gardner, M. N., Scott, T. B., Jackman, S.A., & Thompson, I. P. (2010). Optimization of nano-scalenickel/iron particles for the reduction of high concentrationchlorinated aliphatic hydrocarbon solutions. Chemosphere,79, 448–454.

Barnett, B. R., Evans, A. L., Roberts, C. C., & Fritsch, J. M.(2011). Batch reactor kinetic studies on the reductive dechlo-rination of chlorinated ethylenes by tetrakis-(4-sulfonatophenyl) porphyrin cobalt. Chemosphere, 82, 592–596.

Batley, G. E., Kirby, J. K., & McLaughlin, M. J. (2013). Fate andrisks of nanomaterials in aquatic and terrestrial environments.Accounts of Chemical Research, 46(3), 854–862.

Bennett, P., He, F., Zhao, D. Y., Aiken, B., & Feldman, L. (2010).In-situ testing of metallic iron nanoparticle mobility andreactivity in a shallow granular aquifer. Journal ofContaminant Hydrology, 116(1–4), 35–46.

Berge, N. D.& Ramsburg, C. A. (2010). Iron-mediated trichloro-ethene reduction within nonaqueous phase liquid. JournalContamination Hydrology, 118(3-4), 105–116.

Berge, N. D., & Ramsburg, C. A. (2009). Oil-in-water emulsionsfor encapsulated delivery of reactive iron particles.Environmental Science Technology, 43(13), 5060–5066.

Bezbaruah, A. N., Krajangpan, S., Chisholm, B. J., Khan, E., &Bermudez, J. J. (2009). Entrapment of iron nanoparticles in

calcium alginate beads for groundwater remediation applica-tions. Journal of Hazardous Materials, 166(2–3), 1339–1343.

Brar, S. K., Verma, M., Tyagi, R. D., & Surampalli, R. Y. (2010).Engineered nanoparticles in wastewater and wastewatersludge—evidence and impacts. Waste Management, 30,504–520.

Burghardt, D., Simon, E., Knöller, K., Kassahun, A. (2007).Immobilization of uranium and arsenic by injectible ironand hydrogen stimulated autotrophic sulphate reduction,Journal of Contaminant. Hydrology, 94(3-4), 305–314.

Calvin, S., Carpenter, E. E. & Harris, V. G. (2003).Characterization of passivated iron nanoparticles by x-rayabsorption spectroscopy, Physical Review, B 68(3), 033411.

Cameselle, C., Reddy, K. R. R., Darko-Kagya, K., & Khodadoust,A. (2013). Effect of dispersant on transport of nanoscale ironparticles in soils: zeta potential measurements and columnexperiments. Journal of Environmental Engineering, ASCE,139(1), 23–33.

Cao G. (2004). Nanostructures and nanomaterials. Synthesis,Properties & Applications. London: Imperial CollegePress.

Capek, J. T. (2004). Preparation of metal nanoparticles in water-in-oil (w/o) microemulsions. Advances in Colloid and InterfaceScience, 110(1–2), 49–74.

Carucci, A., Manconi, I. & Manigas, L. (2007). Use of membranebioreactors for the bioremediation of chlorinated compoundspolluted groundwater.Water Sci. Technol., 55(10), 209–216.

Celebi, O., Üzüm, C., Shahwan, T., & Erten, H. N. (2007). Aradiotracer study of the adsorption behavior of aqueous Ba2+ions on nanoparticles of zero-valent iron. Journal ofHazardous Materials, 148, 761–767.

CETESB (2013). Relationship of contaminated and rehabilitatedareas in the State of São Paulo-Brazil. Access: http://www.cetesb.sp.gov.br/userfiles/file/areas-contaminadas/2013/texto-explicativo.pdf. 30-05-14. (in portuguese)

Cheng, R., Wang, J.-L., & Zhang, W.-X. (2007). Comparison ofreductive dechlorination of p-chlorophenol using Fe-0 andnanosized Fe-0. Journal Hazardous Material, 144, 334–339.

Choe, S., Chang, Y. Y., Hwang, K. Y., & Khim, J. (2000). Kineticsof reductive denitrification by nanoscale zero-valent iron.Chemosphere, 41, 1307–1311.

Choe, S., Lee, S. H., Chang, Y. Y., Hwang, K. Y., & Khim, J.(2001). Rapid reductive destruction of hazardous organiccompounds by nanoscale Fe0. Chemosphere, 42, 367–372.

Choi, C.-J., Dong, X.-L., &Kim, B.-K. (2001).Microstructure andmagnetic properties of Fe nanoparticles synthesized bychemical vapor condensation. Materials Transaction,42(10), 2046–2049.

Christiansen, C.M., Damgaard, I., Broholm,M., Kessler, T., Klint,K. E., Nilsson, B., & Bjerg, P. L. (2010). Comparison ofdelivery methods for enhanced in-situ remediationin clay till.Groundwater Monitoring & Remediation, 30(4), 107–122.

Chrysochoou, M., McGuire, M., & Daha, G. (2012). Transportcharacteristics of green-tea nano-scale zero valent iron as afunction of soil mineralogy. Chemical EngineeringTransactions, 28, 121–126.

Chun, C. L., Baer, D. R., Matson, D. W., Amonette, J. E., & Penn,R. L. (2010). Characterization and reactivity of iron nanopar-ticles prepared with added Cu, Pd, and Ni. EnvironmentalScience Technology, 44(13), 5079–5085.


http://randd.defra.gov/

http://www.cetesb.sp.gov.br/userfiles/file/areas-contaminadas/2013/texto-explicativo.pdf



Cirtiu, C. M., Raychoudhury, T., Ghoshal, S., & Moores, A.(2011). Systematic comparison of the size, surface character-istics and colloidal stability of zero valent iron nanoparticlespre- and post-grafted with common polymers. Colloids andSurfaces, A: Physicochemical and Engineering Aspects,390(1–3), 95–104.

Comba, S., & Sethi, R. (2009). Stabilization of highly con-centrated suspensions of iron nanoparticles using shear-thinning gels of xanthan gum. Water Research, 43(15),3717–3726.

Cook, S. M. (2009). Assessing the use and application of zero-valent iron nanoparticle technology for remediation at con-taminated sites. Access: http://www.clu-in.org/download/studentpapers/Zero-Valent-Iron-Cook.pdf. 29-05-2014.

Crane, R. A., & Scott, T. B. (2012). Nanoscale zero-valentiron: future prospects for an emerging water treatmenttechnology. Journal of Hazardous Materials, 211–212,112–125.

Cundy, A. B., Hopkinson, L., & Whitby, R. L. D. (2008). Use ofiron-based technologies in contaminated land and groundwa-ter remediation: a review. Science of the Total Environment,400, 42–51.

Dalla Vecchia, E., Luna, M., & Sethi, R. (2009). Transport inporous media of highly concentrated iron micro- and nano-particles in the presence of xanthan gum. EnvironmentalScience Technology, 43(23), 8942–8947.

Darab, J. G., Amonette, A. B., Burke, D. S. D., & Orr, R. D.(2007). Removal of pertechnetate from simulated nuclearwaste streams using supported zero valent iron. ChemicalMaterials, 19, 5703–5713.

Darko-Kagya, K., Khodadoust, A. P., & Reddy, K. R. (2010a).Reactivity of aluminum lactate-modified nanoscale iron par-ticles with pentachlorophenol in soils. EnvironmentalEngineering Science, 27(10), 861–869.

Darko-Kagya, K., Khodadoust, A. P., & Reddy, K. R. (2010b).Reactivity of lactate-modified nanoscale iron particles with 2,4-dinitrotoluene in soils. Journal of Hazardous Materials,182, 177–183.

Diao, M., & Yao, M. (2009). Use of zero-valent iron nanoparticlesin inactivating microbes. Water Research, 43, 5243–5251.

Dickinson, M., & Scott, T. B. (2010). The application of zero-valent iron nanoparticles for the remediation of a uranium-contaminated waste effluent. Journal of HazardousMaterial,178, 171–179.

Dong, H., & Lo, I. M. C. (2013). Influence of humic acid on thecolloidal stability of surface-modified nano zero-valent iron.Water Research, 47(1), 419–427.

Eglal, M. M. & Ramamurthy, A. S. (2014). Nanofer ZVI: mor-phology, particle characteristics, kinetics, and applications.Journal of Nanomaterials. 2014, ID 152824, 11. Doi:10.1155/2014/152824

Elliot, D. W., Lien, H. L. & Zhang, W.-X. (2009). Degradation oflindane by zero-valent iron nanoparticles, JournalEnvironmental. Engineering. (135), 317–325.

Elliott, D. W. & ZhangW-x, (2001) Field assessment of nanoscalebimetal l ic part ic les for groundwater treatment.Environmental Science Technology. (35),4922–6.

Fahlman. B. D. (2011).Materials chemistry. Springer, 2nd ed. XI,736p.

Fan, J., Guo, Y., Wang, J., & Fan, M. (2009). Rapid decolorizationof azo dye methyl orange in aqueous solution by nanoscale

zerovalent iron particles. Journal of Hazardous Materials,166, 904–910.

Fang, Z., Chen, J., Qiu, X., Cheng, W. & Zhu, L. (2011). Effectiveremoval of antibiotic metronidazole from water by nanoscalezero-valent iron particles. Desalination. 268(1-3),60-67.

Fu, F., Dionysiou, D. D., & Liu, H. (2014). The use of zero-valentiron for groundwater remediation and wastewater treatment:a review. Journal of Hazardous Materials, 267, 194–205.

Gastone, F., Tosco, T., & Sethi, R. (2014). Green stabilization ofmicroscale iron particles using guar gum: bulk rheology,sedimentation rate and enzymatic degradation. Journal ofColloid and Interface Science, 421, 33–43.

Ghauch, A., Tuqan, A., & Assi, H. A. (2009). Antibiotic removalfrom water: elimination of amoxicillin and ampicillin bymicroscale and nanoscale iron particles. EnvironmentalPollution, 157, 1626–1635.

Gillham, R.W. (1996). In-situ treatment of groundwater: metal-enhanced degradation of chlorinated organic. 9, 249-274.

Gillham, R. W., & O’Hannesin, S. F. (1994). Enhanced degrada-tion of halogenated aliphatics by zero-valent iron. GroundWater, 32, 958–967.

Grieger, K. D., Fjordboge, A., Hartmann, N. B., Eriksson, E.,Bjerg P. L., Baun, A. (2010). Environmental benefits andrisks of zerovalent iron nanoparticles, (nZVI) for in situremediation: risk mitigation or trade-off? Journal ofContamination Hydrology, 118(3–4), 165–183.

He, F. & Zhao, D. (2005). Preparation and characterization of anew class of starch-stabilized bimetallic nanoparticles fordegradation of chlorinated hydrocarbons in water.Environmental Science Technology, 39(9),3314-3320.

He, F., & Zhao, D. (2007). Manipulating the size and dispersibility ofzerovalent iron nanoparticles by use of carboxymethyl cellulosestabilizers. Environmental Science Technology, 41, 6216–6221.

He, F., Zhang, M., Qian, T., & Zhao, D. (2009). Transport ofcarboxymethyl cellulose stabilized iron nanoparticles in po-rous media: column experiments and modeling. JournalColloid Interface Science, 334(1), 96–102.

He, F., Zhao, D. & Paul, C. (2010). Field assessment ofcarboxymethyl cellulose stabilized iron nanoparticles for in-situ destruction of chlorinated solvents in source zones.WaterResearch, 44(7), 2360–2370.

Hendren, C. O., Lowry, M., Grieger, K. D., Money, E. S.,Johnston, J. M., Wiesner, M. R., & Beaulieu, S. M. (2013).Modeling approaches for characterizing and evaluating envi-ronmental exposure to engineered nanomaterials in supportof risk-based decision making. Environmental ScienceTechnology, 47(3), 1190–1205.

Henn, K. W., & Waddill, D. W. (2006). Utilization of nanoscalezero-valent iron for source remediation—a case study.Remediation Journal, 16(2), 57–76.

Hoag, G. E., Collins, J. B., Holcomb, J. L., Hoag, J. R.,Nadagouda, M. N., & Varma, R. S. (2009). Degradation ofbromothymol blue by ‘greener’ nano-scale zero-valent ironsynthesized using tea polyphenols. Journal MaterialChemistry, 19, 8671–8677.

Hochella, M. F., Jr., Moore, J. N., Putnis, C. V., Putnis, A.,Kasama, T., & Eberl, D. D. (2005). Direct observation ofheavy metal-mineral association from the Clark Fork RiverSuperfund Complex: implications for metal transport andbioavailability. Geochimica et Cosmochimica Acta, 69(7),1651–1663.


http://www.clu-in.org/download/studentpapers/Zero-Valent-Iron-Cook.pdf

http://www.clu-in.org/download/studentpapers/Zero-Valent-Iron-Cook.pdf

http://dx.doi.org/10.1155/2014/152824

http://dx.doi.org/10.1155/2014/152824

Hosseini, S. M., & Tosco, T. (2013). Transport and retention ofhigh concentrated nano-Fe/Cu particles through highly flow-rated packed sand column.Water Research, 47(1), 326–338.

Hu, N., Li, Z., Huang, P., & Tao, C. (2006). Distribution andmobilityof metals in agricultural soils near a copper smelter in SouthChina. Environmental Geochemistry and Health, 28, 19–26.

Hua, M., Zhang, S., Pan, B., Zhang, W., Lv, L., & Zhang, Q.(2012). Heavy metal removal from water/wastewater bynanosized metal oxides: a review. Journal of HazardousMaterials, 211–212, 317–331.

Hwang, Y. H., Kim, D. G., & Shin, H. S. (2011).Mechanism studyof nitrate reduction by nano zero valent iron. Journal ofHazardous Materials, 185, 1513–1521.

Hydutsky, B. W., Mack, E. J., Beckerman, B. B., Skluzacek, J. M.,&Mallouk, T. E. (2007). Optimization of nano- and microirontransport through sand columns using polyelectrolytemixtures.Environmental Science Technology, 41(18), 6418–6424.

Jiang, Z. M., Lv, L., Zhang, W. M., Du, Q., Pan, B. C.,Yang, L., & Zhang, Q. X. (2011). Nitratereductionusing nanosized zero-valent iron supported by polysty-rene resins: role of surface functional groups. WaterResearch, 45, 2191–2198.

Jiemvarangkul, P., Zhang, W.-X., & Lien, H.-L. (2011). Enhancedtransport of polyelectrolyte stabilized nanoscale zero-valentiron (nZVI) in porous media.Chemical Engineering Journal,170(2–3), 482–491.

Johnson, R. L., Johnson, G. O., Nurmi, J. T., & Tratnyek, P. G.(2009). Natural organic matter enhanced mobility of nanozerovalent iron. Environmental Science Technology, 43,5455–5460.

Johnson, R. L., Nurmi, J. T., O’Brien Johnson, G. S., Fan, D.,O’Brien Johnson, R. L., Shi, Z., Salter-Blanc, A. J., Tratnyek,P. G., & Lowry, G. V. (2013). Field-scale transport andtransformation of carboxymethylcellulose- stabilized nanozero-valent iron. Environmental Science and Technology,47(3), 1573–1580.

Joo, S.H. & Zhao, D. (2008). Destruction of lindane and atrazineusing stabilized iron nanoparticles under aerobic and anaer-obic conditions: effects of catalyst and stabilizer.Chemosphere, 70(3),418-425.

Ju-Nam, Y. & Lead, J. R. (2008). Manufactured nanoparticles: anoverview of their chemistry, interactions and potential envi-ronmental implications. Science of the Total Environmental,400(1-3),396-414.

Kanel, S. R., Manning, B., Charlet L. & Choi H. (2005). Removalof arsenic(III) from groundwater by nanoscale zero-valentiron, Environmental Science Technology, 39(5), 1291–1298.

Kanel, S. R.,Greneche, J. M. & Choi, H. (2006). Arsenic (V)removal from groundwater using nano scale zero-valent ironas a colloidal reactive barrier material, EnvironmentalScience Technology, 40(6), 2045–2050.

Kanel, S. R., Manning, B., Charlet, L., & Choi, H. (2007).Transport of surface-modified iron nanoparticle in porousmedia and application to arsenic(III) remediation. Journalof Nanoparticle Research, 9, 725–735.

Kanel, S. R., Goswami, R. R., Clement, T. P., Barnett, M. O., &Zhao, D. (2008). Two dimensional transport characteristics ofsurface stabilized zero-valent iron nanoparticles in porousmedia. Environmental Science Technology, 42, 896–900.

Karabelli, D., Uzum, C., Shahwan, T., Eroglu, A.E., Lieberwirth,I., Scott, T.B. & Hallam, K.R. (2008). Batch removal of

aqueous Cu2+ ions using nanoparticles of zero-valent iron:a study of the capacity and mechanism of uptake, IndustrialEngineering Chemistry Research, 47(14), 4758–4764.

Karlsson, M. N. A., Deppert, K., Wacaser, B. A., Karlsson, L. S.,& Malm, J. O. (2005). Sizecontrolled nanoparticles by ther-mal cracking of iron pentacarbonyl. Applied Physics A:Materials Science & Processing, 80(7), 1579–1583.

Karn, B., Kuiken, T., & Otto, M. (2011). Nanotechnology and in-situ remediation: a review of the benefits and potential risks.Ciência & Saúde Coletiva, 16(1), 165–178.

Kharisov, B. I., Dias, H. V. R., Kharissova, O. V., Jimenez-Perez,V. M., Perez, B. O., & Flores, B. M. (2012). Iron-containingnanomaterials: synthesis, properties, and environmental ap-plications. RSC Advances, 2(25), 9325–9358.

Kim, T. S., Sun, W., Choi, C.-J., & Lee, B.-T. (2003).Microstructure of Fe nanoparticles fabricated by chemicalvapor condensation. Reviews on Advanced MaterialsScience, 5(5), 481–486.

Kim, J. Y., Park, H. J., Lee, C., Nelson, K. L., Sedlak, D. L., &Yoon, J. (2010). Inactivation of Escherichia coli bynanoparticulate zerovalent iron and ferrous iron. Applied &Environmental Microbiology, 76(22), 7668–7670.

Kim, J. Y., Lee, C., Love, D. C., Sedlak, D. L., Yoon, J., & Nelson,K. L. (2011). Inactivation of MS2 coliphage by ferrous ionand zero-valent iron nanoparticles. Environmental ScienceTechnology, 45(16), 6978–6984.

Kim, S. A., Kamala-Kannan, S., Lee, K. J., Park, Y. J., Shea, P. J.,Lee, W. H., Kim, H. M., & Oh, B. T. (2013). Removal ofPb(II) from aqueous solution by a zeolite–nanoscale zero-valent iron composite. Chemical Engineering Journal, 217,54–60.

Kirschling, T. L., Gregory, K. B., Minkley E. G., Lowry, G. V. &Tilton, R. D. (2010). Impact of nanoscale zero valent iron ongeochemistry and microbial populations in trichloroethylenecontaminated aquifer materials. Environmental ScienceTechnology. 44(9), 3474–3480.

Klaine, S. J., Alvarez, P. J. J., Batley, G. E., Fernandes, T. E.,Handy, R. D., Lyon, D. Y., Mahendra, S., McLaughlin, M. J.,& Lead, J. R. (2008). Nanoparticles in the environment:behavior, fate, bioavailability, and effects. EnvironmentalToxicology and Chemistry, 27(9), 1825–1851.

Klimkova, S., Cernik, M., Lacinova, L., Filip, J., Jancik, D., &Zboril, R. (2011). Zero-valent iron nanoparticles in treatmentof acid mine water from in-situ uranium leaching.Chemosphere, 82, 1178–1184.

Kocur, C. M., Chowdhury, A. I., Sakulchaicharoen, N.,Boparai, H. K., Weber, K. P., Sharma, P., Krol, M.M., Austrins, L., Peace, C., Sleep, B. E., & O’Carroll,D. M. (2014). Characterization of nZVI mobility in afield scale test. Environmental Science Technology,48(5), 2862–2869.

Kocur, C. M., O’Carroll, D. M., Sleep, B. E. (2013). Impact ofnZVI stability on mobility in porous media. Journal ofContaminant Hydrology, 145, 17–25.

Krol, M. M., Oleniuk, A. J., Kocur, C. M., Sleep, B. E., Bennett,P., Xiong, P. Z., & O’Carroll, D. M. (2013). A field-validatedmodel for in-situ transport of polymer-stabilized nZVI andimplications for subsurface injection. Environmental ScienceTechnology, 47(13), 7332–7340.

Kuiken, T. (2010). Cleaning up contaminated waste sites: is nano-technology the answer? Nano Today, 5, 6–8.


Lee, C., Kim, J., Lee, W., Nelson, K., Yoon, J., & Sedlak, D.(2008). Bactericidal effect of zero-valent iron nanoparticleson Escherichia coli. Environmental Science Technology, 42,4927–4933.

Li, T., & Farrell, J. (2000). Reductive dechlorination of trichloro-ethene and carbon tetrachloride using iron and palladized-iron cathodes. Environmental Science Technology, 34, 173–179.

Li, X.-Q., & Zhang, W.-X. (2007). Sequestration of metal cationswith zerovalent iron nanoparticles: a study with high resolu-tion X-ray photoelectron spectroscopy (HR-XPS). TheJournal of Physical Chemistry C, 111(19), 6939–6946.

Li, A., Tai, C., Zhao, Z., Wang, Y., Zhang, Q., Jiang, G., & Hu, J.(2007). Debromination of decabrominated diphenyl ether byresin-bound iron nanoparticles. Environmental ScienceTechnology, 41, 6841–6846.

Li, S. L., Yan, W. L., & Zhang, W. X. (2009). Solvent-freeproduction of nanoscale zero-valent iron (nZVI) with preci-sion milling. Green Chemistry, 11, 1618–1626.

Li, Z., Greden, K., Alvarez, P. J. J., Gregory, K. B., & Lowry, G. V.(2010). Adsorbed polymer and NOM limits adhesion andtoxicity of nano scale zerovalent iron to E. Coli.Environmental Science & Technology, 44(9), 3462–3467.

Lien, H., & Zhang, W. (1999). Reactions of chlorinated methaneswith nanoscale metal particles in aqueous solutions. Journalof Environmental Engineering, 125(11), 1042–1047.

Lin, Y., Weng, C., & Chen, F. (2008). Effective removal of AB24dye by nano/micro-size zero-valent iron. Separation andPurification Technology, 64, 26–30.

Ling, X. F., Li, J. S., Zhu, W., Zhu, Y. Y., Sun, X. Y., Shen, J. Y.,Han, W. Q., & Wang, L. J. (2012). Synthesis of nanoscalezero-valent iron/ordered mesoporous carbon foradsorptionand synergistic reduction of nitrobenzene. Chemosphere,87, 655–660.

Liu, Z. G., & Zhang, F. S. (2010). Nano-zerovalent iron containedporous carbons developedfromwaste biomass for the adsorp-tion and dechlorination of PCBs. Bioresource Technology,101, 2562–2564.

Liu, Y. Q., Majetich, S. A., Tilton, R. D., Sholl, D. S., & Lowry, G.V. (2005). TCE dechlorination rates, pathways, and efficien-cy of nanoscale iron particles with different properties.Environmental Science Technology, 39(5), 1338–1345.

Liu, H. B., Chen, T. H., Chang, D. Y., Chen, D., Liu, Y., He, H. P.,Yuan, P., & Frost, R. (2012). Nitratereduction over nanoscalezero-valent iron prepared by hydrogen reduction of goethite.Materials Chemistry and Physics, 133, 205–211.

Machado, S., Pinto, S. L., Grosso, J. P., Nouws, H. P. A.,Albergaria, J. T., & Delerue-Matos, C. (2013). Green pro-duction of zero-valent iron nanoparticles using tree leaf ex-tracts. Science Total Environmental, 445–446, 1–8.

Martin, J. E., Herzing, A. A., Yan, W. L., Li, X. Q., Koel, B. E.,Kiely, C. J., & Zhang, W. X. (2008). Determination of theoxide layer thickness in core−shell zerovalent iron nanopar-ticles. Langmuir, 24, 4329–4334.

Matheson, L. J., & Tratnyek, P. G. (1994). Reductivedehalogenation of chlorinated methanesby iron metal.Environmental Science Technology, 28, 2045–2045.

Mueller, N. C., Braun, J., Bruns, J., Cerník,M., Rissing, P., Rickerby,D., & Nowack, B. (2012). Application of nanoscale zero valentiron (nZVI) for groundwater remediation in Europe.Environmental Science Pollution Research, 19, 550–558.

Naja, G., Halasz, A., Thiboutot, S., Ampleman, G. & Hawari, J.(2008). Degradation of hexahydro-1,3,5-trinitro-1,3,5-tri-azine (RDX) using zerovalent iron nanoparticles,Environmental Science Technology. 42(12), 4364–4370.

Nanorem (2013) Nanotechnological Remediation Processes fromLab Scale to End User Applications for the Restoration of aClean Environment. Accessed http://www.nanorem.eu/index.aspx . 31/03/2014.

Navarro, E., Baun, A., Behra, R., Hartmann, N., Filser, J., Miao,A., Quigg, A., & Neal, A. (2008). What can be inferred frombacterium-nanoparticle interactions about the potential con-sequences of environmental exposure to nanoparticles?Ecotoxicology, 17(5), 362–371.

Nel, A., Xia, T., Madler, L., & Li, N. (2006). Toxic potential ofmaterials at the nanolevel. Science, 3(311), 622–627.

Niemeyer, C. M. (2001). Nanoparticles, proteins, and nucleicacids: biotechnology meets materials science. AngewandteChemie International Edition, 40(22), 4128–4158.

Njagi, E. C., Huang, H., Stafford, L., Genuino, H., Galindo,H. M., Collins, J. B., Hoag, G. E., & Suib, S. L.(2011). Biosynthesis of iron and silver nanoparticlesat room temperature using aqueous sorghum bran ex-tracts. Langmuir, 27, 264–271.

Nurmi, J. T., Tratnyek, P. G., Sarathy, V., Baer, D. R., Amonette, J.E., Pecher, K., Wang, C. M., Linehan, J. C., Matson, D. W.,Penn, R. L., & Driessen, M. D. (2005). Characterization andproperties of metallic iron nanoparticles: spectroscopy, elec-trochemistry, and kinetics. Environmental ScienceTechnology, 39(5), 1221–1230.

Nutt, M. O., Hughes, J. B., & Wong, M. S. (2005). Designing Pd-on-Au bimetallic nanoparticle catalysts for trichloroetheneHydrodechlorination. Environmental Science Technology,39(5), 1346–1353.

O’Carrol, D. M. (2014). Nanotechnology applications for cleanwater (second edition) solutions for improving water quality.A volume in Micro and Nano Technologies, 441–456. DOI:10.1016/B978-1-4557-3116-9.00028-7.

O’Carroll, D., Sleep, B., Krol, M., Boparai, H., & Kocur, C.(2013). Nanoscale zero valent iron and bimetallic particlesfor contaminated site remediation. Advanced WaterResources, 51, 104–122.

Olegario, J. T., Yee, N., Miller, M., Sczepaniak, J., & Manning, B.(2010). Reduction of Se (VI) to Se (−II) by zerovalent ironnanoparticle suspensions. Journal Nanoparticles Research,12(6), 2057–2068.

Orth, W.S. & Gillham, R.W. (1996). Dechlorination of trichloro-ethene in aqueous solution using Fe–O. EnvironmentalScience Technology. (30):66–71.

Panagos, P., Liedekerke, M. V,, Yigini, Y. & Montanarella, L.(2013). Contaminated sites in Europe: review of the currentsituation based on data collected through a EuropeanNetwork. Journal of Environmental and Public Health. ID158764, 11p. http://dx.doi.org/10.1155/2013/158764

Peralta-Videa, J. R., Zhao, L., Lopez-Moreno, M. L., De La Rosa,G., Hong, J., & Gardea-Torresdey, J. L. (2011).Nanomaterials and the environment: a review for the bienni-um 2008–2010. Journal of Hazardous Materials, 186, 1–15.

Petosa, R., Jaisi, D. P., Quevedo, I. R., Elimelech, M. & Tufenkji,N. (2010). Aggregation and deposition of engineerednanomaterials in aquatic environments: role of physicochem-ical interactions. Environ. Sci. Technol., 44(17), 6532–6549.


http://www.nanorem.eu/index.aspx

http://www.nanorem.eu/index.aspx

http://dx.doi.org/10.1016/B978-1-4557-3116-9.00028-7

http://dx.doi.org/10.1155/2013/158764

Phenrat, T., Saleh, N., Sirk, K., Kim, H.-J., Tilton, R. D., & Lowry,G. V. (2008). Stabilization of aqueous nanoscale zerovalentiron dispersions by anionic polyelectrolytes: adsorbed anion-ic polyelectrolyte properties and their effect on aggregationand sedimentation. Journal of Nanoparticles Research, 10,795–814.

Phenrat, T., Liu, Y., Tilton, R. D. & Lowry, G. V. (2009). Adsorbedpolyelectrolyte coatings decrease Fe0 nanoparticle reactivitywith TCE in water: conceptual model and mechanisms.Environmental Science Technology, 43(5), 1507–1514.

Phenrat, T., Kim, H.-J., Fagerlund, F., Illangasekare, T., & Lowry,G. V. (2010). Empirical correlations to estimate agglomeratesize and deposition during injection of a polyelectrolyte-modified Fe0 nanoparticle at high particle concentration insaturated sand. Journal of Contaminant Hydrology, 118(3–4), 152–164.

Ponder, S. M., Darab, J. G., &Mallouk, T. E. (2000). Remediationof Cr(VI) and Pb(II) aqueous solutions using supported,nanoscale zero-valent iron. Environmental ScienceTechnology, 34, 2564–2569.

Ponder, S. M., Darab, J. G., Bucher, J., Caulder, D., Craig, I.,Davis, L., Edelstein, N., Lukens, W., Nitsche, H., Rao, L. F.,Shuh, D. K., &Mallouk, T. E. (2001). Surface chemistry andelectrochemistry of supported zerovalent iron nanoparticlesin the remediation of aqueous metal contaminants. ChemicalMaterials, 13, 479–486.

Posner, J. D. (2009). Engineered nanomaterials: where they go,nobody knows. Nano Today, 4, 114–115.

Quinn, J., Geiger, C., Clausen, C., Brooks, K., Coon, C., O’Hara,S., Krug, T., Major, D., Yoon, W. S., Gavaskar, A., &Holdsworth, T. (2005). Field demonstration of DNAPLdehalogenation using emulsified zero-valent iron.Environmental Science Technology, 39, 1309–1318.

Reddy, K. R. (2010) Nanotechnology for site remediation:dehalogenation of organic pollutants in soils and groundwa-ter by nanoscale iron particles. In: Proceedings of the 6thInternational Congress on Environmental Geotecnics. NewDelhi. India. 1:163–180.

Reddy, K. R. (2013) Evolution of Geoenvironmental Engineering.Environmental Geotechnics. ICE Publishing. http://dx.doi.org/10.1680/envgeo.13.00088.

Reddy, K. R., Darko-Kagya, K., & Cameselle, C. (2011).Electrokinetic-enhanced transport of lactate-modifiednanoscale iron particlesfor degradation of dinitrotoluenein clayey soils. Separation and Purification Technology,79, 230–237.

Reddy, K. R., Khodadoust, A. P., & Darko-Kagya, K. (2012).Transport and reactivity of lactate-modified nanoscale ironparticles in PCP-contaminated soils. Journal of Hazardous,Toxic, and Radioactive Waste, 16(1), 68–74.

Reddy, K., Darnault, C. & Darko-Kagya, K. (2014). Transport oflactate-modified nanoscale iron particles in porous media.Journal of Geotechnical and Geoenvironmental Engineer.140, (2), 04013013

Reijnders, L. (2006). Cleaner nanotechnology and hazard reduc-tion of manufactured nanoparticles. Journal CleaningProduction, 14(2), 124–133.

Riba, O., Scott, T. B., Ragnarsdottir, K. V., & Allen, G. C. (2008).Reaction mechanism of uranyl in the presence of zero-valentiron nanoparticles. Geochimica et Cosmochimica Acta, 72,4047–4057.

Rosansky, S., Condit, W. & Sirabian, R. (2013). Best practices forinjection and distribution of amendments. Technical ReportTR-NAVFAC-EXWC-EV-1303. 81p. Accessed: http://www.clu-in.org/remediation/

Rotello, V. M. (2004). Nanoparticles: Building Blocks forNanotechnology (1st ed., p. 284). New York: Springer.

Sakulchaicharoen, N., O’Carroll, D. M., & Herrera, J. E. (2010).Enhanced stability and dechlorination activity of pre-synthesis stabilized nanoscale FePd particles. JournalContamination Hydrology, 118, 117–127.

Sakulchaicharoen, N., O’Carroll, D.M. & Herrera, J.E. (2010).Enhanced stability and dechlorination activity of pre-synthesis stabilized nanoscale FePd particles. JournalContamination Hydrology. 118(3-4), 117–127.

Saleh, N., Phenrat, T., Sirk, K., Dufour, B., Ok, J., Sarbu, T.,Matyjaszewski, K., Tilton, R.D. & Lowry, G.V. (2005).Adsorbed triblock copolymers deliver reactive iron nanopar-ticles to the oil/water interface. Nano Letters, 5(12), 2489–2494.

Saleh, N., Sirk, K., Liu, Y., Phenrat, T., Dufour, B.,Matyjaszewski, K., Tilton, R. D., & Lowry, G. V. (2007).Surface modifications enhance nanoiron transport and NAPLtargeting in saturated porous media. EnvironmentalEngineering Science, 24(1), 45–57.

Sarathy, V., Salter, A. J., Nurmi J. T., Johnson. G. O., Johnson, R.L. & Tratnyek P. G. (2010). Degradation of 1,2,3-trichloropropane (TCP): hydrolysis, elimination, and reduc-tion by iron and zinc. Environmental Science Technology,44(2), 787–793.

Satapanajaru, T., Anurakpongsatorn, P., Pengthamkeerati, P. &Boparai, H. (2008). Remediation of atrazine-contaminatedsoil and water by nano zerovalent iron, Water Air SoilPollution, 192(1-4), 349–359.

Schrick, B., Blough, J. L., Jones, A. D., & Mallouk, T. E. (2002).Hydrodechlorination of trichloroethylene to hydrocarbonsusing bimetallic nickel–iron nanoparticles. Chemistry ofMaterials, 14, 5140–5147.

Schrick, B., Hydutsky, B. W., Blough, J. L., &Mallouk, T. E. (2004).Delivery vehicles for zerovalent metal nanoparticles in soil andgroundwater. Chemistry of Materials, 16, 2187–2193.

Scott, T. B., Popescu, I. C., Crane, R. A., & Noubactep, C. (2011).Nano-scale metallic iron for the treatment of solutions con-taining multiple inorganic contaminants. Journals ofHazardous Materials, 186(1), 280–287.

Sevcu, A., El-Temsah, Y. S., Joner, E. J., & Cernik, M. (2011).Oxidative stress induced in microorganisms by zero-valent ironnanoparticles.Microbes and Environments, 26(4), 271–281.

Sharma, H. D., & Reddy, K. R. (2004). Geoenvironmental engi-neering: site remediation, waste containment, and emergingwaste management technologies (p. 961). Hoboken, NewJersey: John Wiley & Sons Inc.

Shen, X., Zhao, L., Ding, Y., Liu, B., Zeng, H., Zhong, L., & Li, X.(2011). Foam, a promising vehicle to deliver nanoparticlesfor vadose zone remediation. Journal of HazardousMaterials, 186, 1773–1780.

Shi, L. N., Zhang, X., & Chen, Z. L. (2011). Removal of chromi-um (VI) from wastewater using bentonite-supported nano-scale zero-valent iron. Water Research, 45, 886–892.

Shih, Y. H., & Tai, Y. T. (2010). Reaction of decabrominateddiphenyl ether by zerovalent iron nanoparticles.Chemosphere, 78, 1200–1206.


http://dx.doi.org/10.1680/envgeo.13.00088

http://www.clu-in.org/remediation/

http://www.clu-in.org/remediation/

Shih, Y., Chen, Y., Chen, M., Tai, Y., & Tso, C. (2009).Dechlorination of hexachlorobenzene by using nanoscaleFe and nanoscale Pd/Fe bimetallic particles. Colloids andSurfaces A, 332(2–3), 84–89.

Shu, H. Y., Chang, M. C., Chen, C. C., & Chen, P. E. (2010).Using resin supported nano zero-valent iron particles fordecoloration of acid blue 113 azo dye solution. Journal ofHazardous Materials, 184, 499–505.

Simunek, J., Jacques, D., Van Genuchten, M.Th. & Mallants.D.(2006). Multicomponent geochemical transport modelingusing the HYDRUS computer software packages. Journalof the American Water Resources Association, 42, 1537–1547.

Sirk, K. M., Saleh, N. B., Phenrat, T., Kim, H. J., Dufour, B., Ok,J., Golas, P. L., Matyjaszewsk, K., Lowry, G. V., & Tilton, R.D. (2009). Effect of adsorbed polyelectrolytes on nanoscalezero valent iron particle attachment to soil surface models.Environmental Science Technology, 43(10), 3803–3808.

Sun, Y.-P., Li, X.-Q., Cao, J., Zhang,W.-X., &Wang, H. P. (2006).Characterization of zerovalent iron nanoparticles. Advancesin Colloid and Interface Science, 120(1–3), 47–56.

Sun, Y.-P., Li, X.-Q., Cao, J., Zhang,W.-X., &Wang, H. P. (2007).A method for the preparation of stable dispersion of zero-valent iron nanoparticles. Colloids and Surfaces, A:Physicochemical and Engineering Aspects, 308, 60–66.

Tang, S. C. N., & Lo, I. M. C. (2013). Magnetic nanoparticles:essential factors for sustainable environmental applications.Water Research, 47, 2613–2632.

Tian, H., Li, J., Mu, Z. & Li, L. (2009). Z.H. Effect of pH on DDTdegradation in aqueous solution using bimetallic Ni/Fe nano-particles. Separation and Purification Technology, 66(1), 84–89.

Tiraferri, A., & Sethi, R. (2009). Enhanced transport of zerovalentiron nanoparticles insaturated porous media by guar gum.Journal of Nanoparticle Research, 11(3), 635–645.

Tiraferri, A., Chen, K. L., Sethi, R., & Elimelech, M. (2008).Reduced aggregation and sedimentation of zero-valent ironnanoparticles in the presence of guar gum. Journal of Colloidand Interface Science, 324(1), 71–79.

Tiraferri, A., Tosco, T., Sethi, R. (2011) Transport and retention ofmicroparticles in packed sand columns at low and interme-diate ionic strengths: experiments and mathematical model-ing. Environmental Earth Science, 633(4), 847–859.

Torkzaban, S., Wan, J., Tokunaga, T. K., & Bradford, S. A. (2012).Impacts of bridging complexation on the transport of surface-modified nanoparticles in saturated sand. Journal ofContaminant Hydrology, 136–137, 86–95.

Tosco, T., & Sethi, R. (2009). MNM1D: a numerical code forcolloid transport in porous media: implementation and vali-dation. American Journal of Environmental Sciences, 5(4),517–525.

Tosco, T., & Sethi, R. (2010). Transport of non-Newtonian sus-pensions of highly concentrated micro- and nanoscale ironparticles in porous media: a modeling approach.Environmental Science Technology, 44(23), 9062–9068.

Tosco, T., Coisson, M., Xue, D. & Sethi, R. (2012). Zerovalentiron nanoparticles for groundwater remediation: surface andmagnetic properties, colloidal stability, and perspectives forfield application. In: Chiolerio, A., A.P. (Eds.), NanoparticlesFeaturing Electromagnetic Properties: Research Signpost,Kerala, p. 201–223.

Tosco, T., Papini, M. P., Viggi, C. C., & Sethi, R. (2014).Nanoscale zerovalent iron particles for groundwater remedi-ation: a review. Journal of Cleaner Production, 77, 10–21.

Tratnyek, P. G., & Johnson, R. L. (2006). Nanotechnology forenvironmental clean up. Nanotoday, 1(2), 44–48.

Tufenkji, N., & Elimelech, M. (2004). Correlation equation forpredicting single-collector efficiency in physicochemical fil-tration in saturated porous media. Environmental ScienceTechnology, 38, 529–536.

U. S. Environmental Protection Agency - USEPA. (2012). Emergingcontaminants—nanomaterials fact sheet. Solid Waste andEmergency Response. EPA 505-F-11-009. May 2012.Available on: http://www.epa.gov/fedfac/pdf/emerging_contaminants_nanomaterials.pdf> Accessed in 25/03/2014.

U. S. Environmental Protection Agency—USEPA (2014).Selected sites using or testing nanoparticles for remediation,<http://www.clu-in.org/remediation/nano-site-list.pdf>.(Accessed 29-05-2014)

U.S. Department of Health and Human Services (USDHHS).Centers for Disease Control and Prevention (2006).Approaches to safe nanotechnology: an information ex-change with NIOSH. http://www.cdc.gov/niosh/topics/nanotech/. Accessed 31/03/2014.

U.S. Environmental Protection Agency - USEPA (2004). EPA’scleaning up the nation’s waste sites: markets and technologytrends (2004 edition): Available on: http://www.epa.gov/superfund/accomp/news/30years.htm. Accessed in 03-26-2014.

U.S. Environmental Protection Agency - USEPA (2007). SciencePolicy Council. Nanotechnology White Paper. U.S.Environmental Protection Agency. Available on: http://www.epa.gov/ncer/nano/publications/whitepaper12022005.pdf. Acessed in 31/03/2014

Üzüm, C., Shahwan, T. A., Eroglu, E., Lieberwirth, I., Scott, T. B.,& Hallam, K. R. (2008). Application of zero-valent ironnanoparticles for the removal of aqueous Co2+ ions undervarious experimental conditions. Chemical EngineeringJournal, 144, 213–220.

Van, G., Th, M., Simunek, J., Leij, F. J., Toride, N., & Sejna, M.(2012). STANMOD: model use, calibration, and validation.transactions of the ASAE. American Society of AgriculturalEngineers, 55, 1353–1366.

Varanasi, P., Fullana, A., & Sidhu, S. (2007). Remediation of PCBcontaminated soils using iron nano-particles. Chemosphere,66, 1031–1038.

Velimirovic, M., Chen, H., Simons, Q., & Bastiaens, L. (2012).Reactivity recovery of guar gum coupled mZVI by means ofenzymatic breakdown and rinsing. Journal of ContaminantHydrology, 142–143, 1–10.

Wang, C.-B., & Zhang, W. X. (1997). Synthesizing nanoscale ironparticles for rapid and complete dechlorination of TCE andPCBs. Environmental Science Technology, 31, 2154–2156.

Wang, W., Jin, Z. H., Li, T. L., Zhang, H., & Gao, S. (2006).Preparation of spherical iron nanoclusters in ethanol–watersolution for nitrate removal. Chemosphere, 65, 1396–1404.

Wang, C. M., Baer, D. R., Amonette, J. E., Engelhard, M. H.,Antony, J., & Qiang, Y. J. (2009). Morphology and electronicstructure of the oxide shell on the surface of iron nanoparticles.Journal of American Chemical Society, 131(25), 8824–8832.

Wang, Q., Lee, S., & Choi, H. (2010). Aging study on the structureof Fe0-nanoparticles: stabilization, characterization, and


http://www.epa.gov/fedfac/pdf/emerging_contaminants_nanomaterials.pdf

http://www.epa.gov/fedfac/pdf/emerging_contaminants_nanomaterials.pdf

http://www.clu-in.org/remediation/nano-site-list.pdf

http://www.cdc.gov/niosh/topics/nanotech/

http://www.cdc.gov/niosh/topics/nanotech/

http://www.epa.gov/superfund/accomp/news/30years.htm

http://www.epa.gov/superfund/accomp/news/30years.htm

http://www.epa.gov/ncer/nano/publications/whitepaper12022005.pdf



reactivity. The Journal of Physical Chemistry C, 114(5),2027–2033.

Weber, E. J. (1996). Iron-mediated reductive transformations:investigation of reaction mechanism. EnvironmentalScience Technology, 30(2), 716–719.

Wei, Y. T.,Wu, S. C., Chou, C.M., Che, C. H., Tsai, S. M., & Lien,H. L. (2010). Influence of nanoscale zero-valent iron ongeochemical properties of groundwater and vinyl chloridedegradation: a field case study.Water Research, 44, 131–140.

Wong, M. S., Alvarez, P. J. J., Fang, Y., Akcin, I. N., Nutt, M. O.,Miller, J. T., & Heck, K. N. (2009). Cleaner water usingbimetallic nanoparticle catalysts. Journal of ChemicalTechnology and Biotechnology, 84, 158–166.

Xia, T., Kovochich, M., Brant, J., Hotze, M., Sempf, J., Oberley,T., Sioutas, C., Yeh, J., Wiesner, M., & Nel, A. (2006).Comparison of the abilities of ambient and manufacturednanoparticles to induce cellular toxicity according to an ox-idative stress paradigm. Nano Letters, 6, 1794–1807.

Xiong, Z., Zhao, D., & Pan, G. (2007). Rapid and completedestruction of perchlorate in water and ion-exchange brineusing stabilized zero-valent iron nanoparticles. WaterResearch, 41, 3497–3505.

Xiu, Z.-M., Gregory, K. B., Lowry, G. V., & Alvarez, P. J. J.(2010). Effect of bare and coated nano-scale zero-valent ironon tceA and vcrA gene expression in dehalococcoides spp.Environmental Science Technology, 44, 7647–7651.

Xu, Y., & Zhao, D. (2007). Reductive immobilization of chromatein water and soil using stabilized iron nanoparticles. WaterResearch, 41, 2101–2108.

Yan,W. L., Ramos, M. A. V., Koel, B. E., & Zhang, W. X. (2012).Sequestration by iron nanoparticles: study of solid-phaseredox transformations with X-ray photoelectron spectrosco-py. Journal of Physical Chemistry C, 116, 5303–5311.

Yan, W., Lien, H.-L., Koel, B. E., & Zhang, W.-X. (2013). Ironnanoparticles for environmental clean-up: recent develop-ments and future outlook. Environmental Science:Processes & Impacts, 15, 63–77.

Yang, G. C. C., Tu, H.-C., & Hung, C.-H. (2007). Stability ofnanoiron slurries and their transport in the subsurface envi-ronment. Separation and Purification Technology, 58(1),166–172.

Yao, K. M., Habibian, M. T., & O’Melia, C. R. (1971). Water andwaste water filtration. Concepts and applications.Environmental Science Technology, 5(11), 1105–1112.

Yoo, B. Y., Hernandez, S. C., Koo, B., Rheem, Y., &Myung, N. V.(2007). Electrochemically fabricated zero-valent iron, iron–nickel, and iron–palladium nanowires for environmental re-mediation applications. Water Science and Technology, 55,149–156.

Zhang, W.-X. (2003). Nanoscale iron particles for environmentalremediation: an overview. Journal of Nanoparticle Research,5, 323–332.

Zhang, W., Wang, C., & Lien, H. (1998). Catalytic reduction ofchlorinated hydrocarbons by bimetallic particles. CatalysisToday, 40(4), 387–395.

Zhang, X., Lin, Y., Chen, Z. (2009). 2,4,6-Trinitrotoluene reduc-tion kinetics in aqueous solution using nanoscale zero-valentiron. Journal of Hazardous Material, 165, 923–927.

Zhang, X., Lin, S., Chen, Z. L., Megharaj, M., &Naidu, R. (2011).Kaolinite-supported nanoscale zero-valent iron for removalof Pb2+ from aqueous solution: reactivity, characterizationand mechanism. Water Research, 45, 3481–3488.

Zhang, X., Lin, Y., Shan, X. Q., Chen, Z. (2010). Degradation of 2,4,6-trinitrotoluene (TNT) from explosive wastewater usingnanoscale zero-valent iron. Chemical Engineering Journal,158, 566–570.

Zhang, R., Li, J., Liu, C., Shen, J., Sun, X., Han, W., & Wang, L.(2013). Reduction of nitrobenzeneusing nanoscale zero-valent iron confined in channels of ordered mesoporoussilica.Colloids and Surfaces, A: Physicochemical and EngineeringAspects, 425, 108–114.

Zhu, H.J., Jia, Y. F., Wu, X., Wang, H. (2009). Removal of arsenicfrom water by sup-ported nano zerovalent iron on activatedcarbon. Journal of Hazardous Material, 172, 1591–1596.


review of nanotechnology for soil and groundwater ... · review of nanotechnology for soil and...

Documents