Accepted Manuscript

Title: Environmental remediation and monitoring of cadmium

Author: Md. Khairy, Sherif A. El-Safty, Md. Shenashen

PII: S0165-9936(14)00158-7

DOI: http://dx.doi.org/doi:10.1016/j.trac.2014.06.013

Reference: TRAC 14285

To appear in: Trends in Analytical Chemistry

Please cite this article as: Md. Khairy, Sherif A. El-Safty, Md. Shenashen, Environmental

remediation and monitoring of cadmium, Trends in Analytical Chemistry (2014),

http://dx.doi.org/doi:10.1016/j.trac.2014.06.013.

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1

Environmental remediation and monitoring of cadmium

Md. Khairy a, Sherif A. El-Safty

a, b, *, Md. Shenashen

a

a National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan

b Graduate School for Advanced Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku-ku,

Tokyo 169-8555, Japan

HIGHLIGHTS

Cadmium ions are environmental toxins and induce genomic instability

WHO and EPA recommend a 0.003 mg/L standard for cadmium in drinking water

The development of sensor/captor or combination of platforms urgently required

Fast signal, stability, efficiency, sensitivity, selectivity, reusability needed

Up-to-date developments in approaches to controlling cadmium-ion toxicity

ABSTRACT

The complete remediation of extremely toxic elements, such as cadmium, must be achieved

to control the various stages in their life cycles, from mining as virgin ore to using them as

consumer and industrial end products, and recycling. Considerable progress has been made

in monitoring cadmium ions, but sensors or captors that can simultaneously detect and

remove toxic metal ions across a wide range of environments are still greatly needed. This

article reviews the tools and the strategies for the environmental remediation of cadmium

ions, with special emphasis on state-of-the-art colorimetric sensors. Selective colorimetric

sensors based on immobilization of hydrophobic or hydrophilic chromophore molecules

into nanosized space cavities have significant advantages because of their dual

functionality, namely, early warning “detection” and removal of cadmium ions. This

review concludes with a thorough evaluation of emerging challenges and future

requirements in monitoring, detecting, and removing cadmium ions from environmental

matrices.

Keywords:

Adsorption

Cadmium

Colorimetric sensor

Detection

Fluorescence sensor

Mesoporous captor

Removal

Sensing

Toxicity

Waste management

* Corresponding author. Tel.: +8129-859-2135. Fax: +81 29-859-2501.

E-mail address: sherif.elsafty@nims.go.jp; sherif@aoni.waseda.jp (S.A. El-Safty)

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1. Introduction

Environmental pollution is a real, growing problem that urgently needs to be controlled.

A wide range of toxic inorganic and organic chemicals is currently discharged into the

environment in the form of industrial waste and causes serious air, soil, and water

contamination [1]. Heavy metals are commonly found in wastewaters from chemical

manufacturing, paint and coating, mining, extractive metallurgy, nuclear, and other

industries. These heavy metals must be removed completely prior to discharge of industrial

wastes to the environment. Among the heavy metals, cadmium ions have attracted much

attention because of their hazardous nature [2,3].

As one of the transition metals, cadmium is a soft, silver-white or bluish-white metal

that is chemically similar to zinc and mercury. The average concentration of cadmium in

the Earth’s crust is 0.1–0.5 ppm. Cadmium is widely used in pigments, plastics stabilizers,

batteries, solar panels, and corrosion-resistant steel plating. Based on the British Geological

Survey in 2010, the total world production of cadmium is around 22,300 tons [4].

Cadmium is continually transported between the three main environmental compartments:

air, water, and soil.

The Comprehensive Environmental Response, Compensation, and Liability Act in USA

has ranked cadmium as seventh in its priority list of top 275 hazardous materials [5].

Tobacco is the most important source of cadmium in air. A cigarette contains about 0.5–2

µg of cadmium, approximately 10% of which is inhaled by the smoker. The occupational

exposure standards for cadmium were formerly set at 100–200 µg/m³, but, for the past 40

years, the exposure standard was specified at 2–50 µg/m³. Human exposure

to cadmium induces genomic instability through complex and multifactorial mechanisms,

including proteinuria, a decrease in glomerular filtration rate, and an increase in the

frequency of kidney-stone formation that causes certain forms of cancer [6–11]. The World

Health Organization and the Environmental Protection Agency recommend a 0.003 mg/L

standard for Cd(II) in drinking water [12–15].

Several physical and chemical approaches to removal of cadmium ions from different

environmental matrices have been reported, including chemical methods (e.g., precipitation

and cementation), liquid-liquid extraction, cloud-point extraction and solid-phase

extraction based on adsorption or ion exchange, electroanalytical techniques, flame atomic

absorption spectrometry and inductively-coupled plasma mass spectrometry (broadly used

for its sensitive determination) [16–22]. Among these approaches, the colorimetric solid

sensor has the lowest cost and is the easiest to use, most reliable sensor for environmental

or biological matrices. This review surveys the various tools and strategies of detecting and

removing cadmium ions from biological and environmental samples (Fig. 1).

2. Removal of cadmium ions

2.1. Chemical

Precipitation is the most commonly used method for removal of heavy metal hydroxides,

carbonates, or sulfides because of its low cost and simplicity. Cadmium can be precipitated

using barium acetate, diisobutyldithiophosphinate, lime, and magnesium [23]. Cadmium

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can also be cemented using zinc powder [24]. Although precipitation is a simple, low-cost

method, its applicability and practicality at low concentrations remain a challenge.

2.2. Solvent extraction

Solvent extraction is used mainly in recovering or separating metal ions from highly

concentrated aqueous solutions to obtain very pure solutions. Reddy et al. reported

different solvents (TOPS 99, Cyanex 923, Cyanex 272, Cyanex 302, and Cyanex 301) from

sulfate solutions, which can be diluted in kerosene to remove cadmium [25]. However, this

approach requires discharge of a large amount of toxic solvent from the extracted phase,

which must be replenished in a costly stripping step. As such, this technique is not

advisable for removing heavy metals at low concentration, given the high cost of recovery.

2.3. Ion exchange

An ion-exchange process is a chemical reaction emerging from the contact between an

electrolyte in a solution and an insoluble electrolyte. The ion-exchange mechanism

between a heavy metal (cadmium) and hydrogen ions can be carried out using Amberlite

IR120, dolamite, Dowex 50 W, and Amberlite IRC 718 [26]. However, the separation

process requires expensive equipment and high operational costs as a result of using

chemicals for resin regeneration.

2.4. Membrane separation

The liquid-membrane process incorporates a dispersed emulsion, including organic

membrane and aqueous internal phase, in a continuous external phase (W/O/W). Various

types of membrane process are employed to remove cadmium from aqueous solutions, such

as liquid membranes, hollow-fiber-supported liquid membranes, and emulsion liquid

membranes. However, these separation-membrane technologies show limitations in terms

of fouling caused by inorganic and organic substances present in wastewaters, and reduced

durability and instability of the membranes under salty or acidic conditions [27].

2.5. Bio-detection/adsorption

Microorganisms, fungi, seaweeds, seaweed derivatives, and waste materials are also

useful for the removal of cadmium [28]. The removing system that comprises dead cells

has no metal-toxicity limitations, does not need growth media and nutrients, and is easy to

strip and reuse [29]. Aspergillus oryzae and Streptomyces lunalinharesii strains can be used

effectively in the bioadsorbent removal of cadmium ions [30,31].

A number of agricultural wastes have also been explored, including spent grain, tree

ferns, and activated carbon produced from various sources, such as almond shells,

sawdust-based granular activated carbon (GAC), tree bark, bone char, tea leaves, wood

charcoal, coconut-shell carbon, sulfurized activated carbon, ozonized activated carbon, rice

hulls, rice bran, and pine bark [32–36]. The adsorption process of these materials is

attributed to binding functional groups, such as carbonyl, hydroxyl, sulfate, phosphate, and

amino groups.

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Microbially-produced surfactants have the advantage of being potentially less toxic and

more biodegradable than some synthetic surfactants. An anionic rhamnolipid biosurfactant

produced by Pseudomonas aeruginosa has been shown to promote the biodegradation of

low-soluble hydrocarbons and to remove cadmium contaminants from the soil [37,38]. The

maximum removal rates of cadmium ions from clean solutions, and from solutions

contaminated with Zn and Cu were approximately 57%, 36%, and 48%, respectively.

Chitosan, a natural biopolymer, is a non-toxic, biodegradable, biocompatible, and

hydrophylic material that can form complexes with metals. Chitosan-coated perlite beads

are used for cadmium adsorption within a concentration range 100–5000 ppm [39–41].

Their maximum adsorption capacity is 78–178.6 mg/g of beads. Despite the cost

effectiveness of the Cd2+

-ion adsorption, the selectivity and the low concentration

sensitivity are major challenges of this technology.

3. Detection of cadmium ions

3.1. Fluorescent and colorimetric-based chemosensors

Chemical sensors are molecular receptors that transform their chemical information into

analytically useful signals upon binding with specific molecules. In general, problems with

the fabrication of chemosensors, namely, time-consuming and complicated syntheses, as

well as high capital and operating costs, need to be solved. Different types of receptor have

been employed for several metal ions, and they can be classified based on their molecular

size (i.e., small molecules and macromolecules) [42–55].

3.1.1. Chemosensors based on small molecules

Anthracene-based compounds are widely used for fluorescent sensors of cadmium ions

[44–46]. Yoon et al. [44] and Gunnlaugsson et al. [46] synthesized anthracene derivatives

with iminomethyl diacetic acid moiety at 9,10- and 1,8- positions for selective fluorescent

cadmium chemosensors (Table 1).

Sensor (1) exhibited a selective, large chelation-enhanced fluorescence (CHEF) effect

by a photoinduced electron-transfer (PET) mechanism, though only a relatively small

CHEF effect was associated with Zn2+

. The association constants for Cd2+

and Zn2+

were

calculated as 69,100 M-1

and 3200 M-1

, respectively.

Cd2+

sensor (2) complex displayed a unique red-shifted broadband because of the

chelatoselective fluorescence perturbation of electrophilic aromatic cadmiation, a

phenomenon similarly observed in sensors (3) and (4).

Moreover, 8-aminoquinoline (8-AQ) or 8-hydroxyquinoline (8-HQ) are used

traditionally in quantitative chemical assay of different transition-metal ions, such as Cd2+

,

which are based on a PET or an internal charge-transfer (ICT) mechanism [48–50,54–57].

Similar fluorescence changes, including changes in intensity and shifts in wavelengths, are

usually observed when Zn2+

and Cd2+

are coordinated with fluorescent sensors [sensors (5)

to (11)] [57].

Palacios et al. [57] designed fingerprint-like fluorescence sensor arrays based on 8-HQ

ligands with extended conjugated fluorophores to provide a turn-on and ratiometric signal

output.

3.1.2. Chemosensors based on macromolecules

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From their description in 1891 by Villiers et al., cyclodextrin molecules have been

applied in many different areas [58]. Liu et al. linked 8-HQ fluorophore to β-cyclodextrin

using the triazole group as a linker to generate a fluorescent Cd2+

sensor with good water

solubility. The Cd2+

addition enhances fluorescence by inhibiting the PET process. The

limit of detection (LOD) of Cd2+

was found at 1.89 x 10-3

M. Moreover, the use of sodium

adamantine carboxylate as a co-chelating agent increased the binding constant (log Ks)

from 2.10 to 3.38 without affecting the emission wavelength [59].

Prodi et al. synthesized 5-chloro-8-methoxyquinoline appended diaza-18-crown-6 as a

chemosensor for Cd2+

[47].

Vicens et al. designed a novel calix[4]arene-based fluorescent chemosensor for the

highly selective detection of Cd2+

and Zn2+

over other metal ions. The association constants

of Cd2+

and Zn2+

were determined as 5.18 x 104

M-1

and 1.7 x 104

M-1

, respectively [60].

3.2. Advanced chemosensors based on functional carrier materials

3.2.1. Organic membrane

The optical sensor-based organic membrane for Cd2+

was developed by applying

2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA) on a cellulose triacetate membrane

[61–63], 5,10,15,20-tetra(p-sulfonatophenyl) porphyrin [64] and 2-(5-bromo-2-pyridylazo)-

5-(diethylamino)phenol on XAD-4 (Br-PADAP/XAD-4) membrane [65], and 1,2-bis-

(quinoline-2-carboxamido)-4-chloro-benzene on PVC [66] and 1-(2-pyridylazo)-2-naphtol

(PAN) on the tri-(2-ethylhexyl) phosphate (TEHP) plasticized cellulose-triacetate matrix.

Matsunaga et al. also reported the potential use of chemically synthesized amphiphilic

4-n-dodecyl-6-(2-thiazolylazo) resorcinol (DTAR) monolayers on different polymeric

membranes as a solid-state chromoionophore sensor (Fig. 2). The sensor strips were

selective and sensitive to cadmium ions and encountered no major interference from

coexisting transition ions and other cationic and anionic species.

Although these optical sensor membranes exhibited good analytical sensitivity, they

required extractants of ionophores and showed a slow response time and low

reproducibility and applicability to environmental applications.

3.2.2. Paper-based microfluidic devices

In patterning papers with hydrophobic barriers, the hydrophilic channel can easily be

produced to control reagents and biological liquids. Feng et al. proposed an

enrichment-based method to enhance the sensitivity of paper-based microfluidic devices by

combining eight pyridylazo compounds and array technologies based on pattern

recognition (Fig. 3). The fast and sensitive detection of cadmium ions at a low

concentration of 50 μM was achieved. The enrichment-based pyridylazo-compound-array

paper performs well in the presence of various common, potentially interfering agents and

has shown excellent stability. This approach is simple and easy to use, but limited detection

and reversibility challenge its application in point-of-care devices or on-site diagnosis [67].

3.2.3. Nanoparticle-based detection

Surface-enhanced Raman spectroscopy (SERS) has emerged as a powerful technique

with an extraordinary sensitivity in applications to chemical and biological systems because

of its interparticle plasmonic coupling induced by the self-aggregation of metal

nanoparticles. A class of sensitive, selective turn-on SERS sensors for Cd2+

ions comprises

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gold nanoparticles (AuNPs) encoded with 2-(4-(2-hydroxyethylamino)-4-

oxobutanamido)ethyl methacrylate [68] and 4-amino-3-hydrazino-5-mercapto-1,2,4-

triazole [69]. The LOD was found to be 1.0 μM and 30 nM, respectively (Fig. 4).

Functional nucleic acids are used as target-recognition elements in sensing applications

because of their competitive advantages over other biological tools. Zhou et al. proposed an

exponential enrichment strategy that immobilizes ssDNA libraries rather than target

molecules on a matrix for the selection of aptamers with high affinity to Cd(II). The Cd-4

aptamer is considered a recognition element for the colorimetric detection of Cd(II) based

on the aggregation of AuNPs by the cationic polymer. The dissociation constant (Kd) of the

Cd-4 aptamer was 34.5 nM for Cd(II). The LOD of Cd(II) in the aqueous solution was 4.6

nM [70]. Although SERS showed high sensitivity, high selectivity and low LOD, its

applicability, practicality, and recyclability remain as major challenges.

To date, there is no single sensing class or technology that can effectively remove and

detect cadmium in every possible environment, so selecting the optimal sensing and

removal approaches from a group of technologies may be the best method to address

sensing or removal needs of Cd2+

ions in environments. The drawbacks of these

conventional sensing and collecting technologies include high power requirements, lack of

flexibility, relatively high operating costs, and time-consuming real-time detection. These

disadvantages make these technologies less likely candidates for widespread use in

Cd2+

-ion monitoring and for making optical mesoporous captors capable of controlled

recognition and signaling of toxic Cd2+

-ion species. Thus, development of the solid porous

membrane optical captor class or combination of platforms is required urgently.

4. Dual function approaches to cadmium-ion monitoring (detection and removal)

4.1. Electrochemical

Various electrochemical methods have been explored for removal and detection of both

macro and trace amounts of cadmium ions. Mercury or mercury film-based electrodes are

widely used because of their amalgamation process, which provides stripping with high

sensitivity and reproducibility [71]. However, the toxicity of mercury limits its

applicability.

An electrochemical methodology was developed for the bio-monitoring of cadmium

ions in artificial and diluted human oral (saliva) fluids at low-ppb levels using in-situ

bismuth film-based modified screen-printed electrodes [72]. However, the interfering ions

posed a major challenge in this method. As a response to this problem,

chemically-modified electrodes were developed, including triphenylphosphine-modified

carbon nanotubes [73] and carbon electrodes modified with 4-amino salicylic acid [74],

Schiff base [75], and p-tert-butylthiacalix[4]arene [76]. Under optimal conditions, the

LODs of Cd2+

ions were observed at 7.4 × 10−5

M and 0.08 μg /L.

Ping et al. evaluated the electro-remediation of metals, such as Cd2+

, from abandoned

industrial sites in China with a concentration of 200 mg/kg [77]. The polarity-exchange

electro-remediation led to a 94% removal rate of Cd2+

. This approach was used to extract

cadmium from kaolin and was shown to have a 98% extraction rate for cadmium and a

63% extraction rate for partially precipitated cadmium at the catholyte (Fig. 5) [78]. The

average extraction rate for Cd2+

in kaolin was 0.38 mg/h, with more than 10% of the Cd2+

remaining, while the average extraction rate for the remaining 10% of Cd2+

noticeably

decreased within the range of 0.025 mg/h to 0.059 mg/h. Despite the success rate of the

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Cd2+

-ion extraction using this technology, the intensive energy use, high capital cost and

relatively low efficiency at dilute concentration remain challenges.

4.2. Optical mesoporous captor membrane

The connectivity and large surface area-to-volume ratios, well-defined pore sizes in their

spherical and cylindrical cavities of meso-scale materials are expected to lead to substantial

improvements in chemical analysis (particularly in optics, mass transport properties,

specificity, and the amplification of chemical processes), through nano-fabrication.

Although successfully designed optical mesosensors have allowed scientists to develop

controlled assessment processes for the naked eye, the following challenges remain:

detection of toxic Cd2+

ions up to nanomolar concentrations;

controlled synthesis;

end-use conditions; and,

efficient removal of Cd2+

ions using a single, rational mesoporous sensor/captor design.

Two key factors in controlling the mesoporous sensor/captor design should be

considered: receptors and immobilization or transducing platforms. Receptors are organic

moieties responsible for the selectivity of the sensor, while platforms are responsible for

the stability and the sensitivity of the sensor, which depend on the technique used (e.g.,

optical and electrochemical).

Mesoporous monolithic membrane materials have attracted considerable attention

because of their highly uniform channels, large surface area, narrow pore-size distribution,

and tunable pore sizes (2–30 nm) over a wide range. These excellent properties result in

diffusion, mass transport, and adsorption better than other materials and provide support for

immobilized sensing moieties. Moreover, the incorporation of aluminum into the

framework has provided materials and allowed the formation of acidic active sites. These

aluminosilica materials demonstrate exciting sensing applications despite their disorderly

structures [79–99]. The monofunctionalization of the inner surface or successive inclusion

of different organic moieties can be achieved by co-condensation or post-synthetic covalent

grafting of organic compounds that yield high-order hybrid materials [86–92]. The metal

ions can then interact with organic moieties by non-covalent bonding, such as hydrogen

bonding, metal coordination, hydrophobic forces, van der Waals forces, π-π interactions,

and electrostatic and/or electromagnetic effects.

For example, El Safty and co-workers reported newly developed techniques for the

controlled design of an optical mesoporous captor based on the fine-tuned surface

patterning of the mesoscopic solid-scaffolding architectures by using dispersible active

agents that led to the dense decoration of receptor-signaling centers inside the mesopore

cavities. In addition, the developments illustrate the applicability of several grafting

strategies that use hard or soft modifier-coupling agents of carriers in developing optical

mesoporous sensors for Cd2+

ions in different environmental matrices (Fig. 6). In such

design techniques, the strong binding site-Cd2+

interaction enabled the remarkably selective

removal of toxic Cd2+

ions from water, wastewater and physiological fluids (blood) without

any toxicological effects on the red blood cells (RBCs). Such nano-engineered hybrid

materials possess the advantages of optical transparency (in the visible to UV range), high

dye dispersion, mechanical robustness, and high processability [82–97]. These mesoporous

sensor/captor responses can be triggered by a target Cd2+

-ion species and transduce

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measurable optical signals under synergistic pH, reaction temperature, and contact-time

“response time” conditions, enabling the binding of the Cd2+

ions into a hydrophobic or

hydrophilic ligand pocket to be mimicked. The optical mesoporous captor showed not only

colorimetric detection, but also removal of Cd2+

ions from these environmental matrices.

These techniques of optical mesoporous captor of Cd2+

ions have significant features that

we summarize as follows [86–102].

(1) Simple synthesis of micro-sized optical mesoporous captor membrane, which result in

low operating costs and easy-to-use colorimetric detection in different morphologies,

such as rings or discs.

(2) Easy accessibility of Cd2+

ions and rapid ligand-Cd2+

binding, regardless of the

controlled platforms of mesopore cavities in “pool- or sink-like sensing assays”.

(3) High loading and perfect accommodation of activated surface agents and receptors

inside large, open mesopores, which lead to detection and removal of

ultra-concentrations of Cd2+

ions.

(4) No pre-concentration process required because of the precise immobilization of

receptors in well-defined, homogenous, densely-patterned organization arrays.

(5) Fast diffusion of Cd2+

ions across dye molecules without significant kinetic hindrance,

which leads to easy generation and transduction of optical color signals as a response

to probe-Cd2+

-binding events.

(6) Chemical and mechanical stability of optical mesoporous captors with sensing and

removal assays of Cd2+

ions.

(7) Long-term stability under storage without maintenance requirements and no significant

changes in the sensing/removal efficiency of Cd2+

ions.

(8) High sensitivity and simple practicality with fast response time and high flux of Cd2+

ions across probe molecules due to mesostructured properties.

(9) Applicability of optical nanosensors in the selective discrimination of trace levels of

Cd2+

ions from environmental samples and waste-disposal systems with a

high-tolerance level, high response speed and confidence during detection of Cd2+

analytes

(10) Reversibility by conducting a simple chemical treatment (e.g., stripping agent, such

as EDTA and HCl) to strip the toxic Cd2+

ions

(11) Fully-controlled assessment processes, sensitive quantification with high-level

precision (i.e., standard calibration curves) and simple recognition, and detection of a

broad range of Cd2+

ions by identifying color changes or fluorescence signals at a

frequency detectable by the human eye.

(12) Simple sequestering and visual detection over a wide, adjustable range, and the

sensitive quantification of Cd2+

ions at trace levels.

(13) pH-dependent signaling response with a high Cd2+

ion flux, ion transport, and affinity

of Cd2+

-probe-ligand binding, which are significantly affected by the pH solution.

Hence, the development of optical mesoporous captors has attracted interest in dual

functionality (detection and removal) of toxic Cd2+

ions. But, the main questions to be

answered in this study were how the optical mesoporous captor membranes can show

feasibility in real-life applications in terms of sampling control, end-use practicality at low

trace levels of Cd2+

? It is therefore essential to control assessment processes, and

commercialized devices for precise determination of these Cd2+

ions at trace levels in the

environment, including soil, water and air.

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5. Conclusions and outlook

This review focused on the recent trends in monitoring cadmium ions in aqueous

solutions, soils, sediments, and biological matrices to control environmental pollution. We

explored an integrated approach, developing a cadmium-sensing and removal platform with

high sensitivity, efficiency, selectivity, reusability, fast contact time, and low cost. This

review also described recent developments in fluorescent and colorimetric receptors. We

gave particular attention to mesocaptor design based on a dense pattern of addressable

receptors set into mesocage porous scaffolds for optical recognition and complete removal

of cadmium ions from various matrices as a result of their physicochemical characteristics.

Such a mesocaptor was designed for use in detection and removal of toxic Cd2+

ions from

drinking water, wastewater and physiological fluids, such as blood. Despite the substantial

improvements in chemical analysis (particularly optics, mass-transport properties,

specificity, and amplification of chemical processes), through to nano-fabrication, the

development of smart, simple, end-use conditions, and the efficient removal and

eco-friendly detection of Cd2+

ions in environments (soil, water and air) or physiological

system remain a critical issue.

References

[1] G. Aragay, J. Pons, A. Merkoҫi, Recent trends in macro-, micro-, and nanomaterial-based

tools and strategies for heavy-metal detection, Chem. Rev. 111 (2011) 3433-3458.

[2] Z. Guo, S. Park, J. Yoon, I. Shin, Recent progress in the development of near-infrared

fluorescent probes for bioimaging applications, Chem. Soc. Rev. 43 (2014) 16.

[3] H. N. Kim, W. X. Ren, J. S. Kim, J. Yoon, Fluorescent and colorimetric sensors for detection

of lead, cadmium, and mercury ions, Chem. Soc. Rev. 41 (2012) 3210- 3244.

[4] L.E. Hetherington, T.J. Brown, A.J. Benham, T. Bide, P.A.J. Lusty, V.L. Hards, S.D. Hannis,

N.E. Idoine, World Mineral Production - British geology survey, London, 2008, pp. 15.

[5] T. C. Jennings, PVC handbook. Hanser Verlag, 2005. pp. 149; M.J. Mench, Cadmium

availability to plants in relation to major long-term changes in agronomy systems, Agricult.

Ecosyst. Environ. 67 (1998) 175-187.

[6] C.T. McMurray, J.A. Tainer, Cancer, cadmium and genome integrity, Nat. Genet. 34 (2003)

239-241.

[7] J. Goel, K. Kadirvelu, C. Rajagopal, V.K. Garg, Cadmium (II) uptake from aqueous

solution by adsorption on carbon aerogel using a response surface methodological approach,

Ind. Eng. Chem. Res. 45 (2006) 6531.

[8] M. Filipič, Mechanisms of cadmium induced genomic instability. Mutat. Res-Fund. Mol. M.

733 (2012) 69-77.

[9] G. Bertin, D. Averbeck, Cadmium: cellular effects, modifications of biomolecules,

modulation of DNA repair and genotoxic consequences, Biochimie, 88 (2006) 1549.

[10] A. Martelli, E. Rousselet, C. Dycke, A. Bouron, J.M. Moulis, Cadmium toxicity in animal

cells by interference with essential metals, Biochimie 88 (2006) 1807.

[11] M. H. Lee, K.K. Cho, A.P. Shah, P. Biswas, Nanostructured sorbents for capture of

cadmium species in combustion environments, Environ. Sci. Technol. 39 (2005) 8481.

[12] J. Goel, K. Kadirvelu, C. Rajagopal, V.K. Garg, Cadmium(II) uptake from aqueous solution

by adsorption onto carbon aerogel using a response surface methodological approach, Ind.

Eng. Chem. Res. 45 (2006) 6531.

[13] M. Taki, M. Desaki, A. Ojida, S. Iyoshi, T. Hirayama, I. Hamachi, Y. Yamamoto,

Fluorescence imaging of intracellular cadmium using a dual-excitation ratiometric

chemosensor, J. Am. Chem. Soc. 130 (2008) 12564.

Page 9 of 18

10

[14] X. Peng, J. Du, J. Fan, J. Wang, Y. Wu, J. Zhao, S. Sun, T. Xu, A selective fluorescent

sensor for imaging Cd2+

in living cells, J. Am. Chem. Soc. 129 (2007) 1500.

[15] T. Cheng, Y. Xu, S. Zhang, W. Zhu, X. Qian, L. Duan, A Highly sensitive and selective

off-on fluorescent sensor for cadmium in aqueous solution and living cell, J. Am. Chem. Soc.

230 (2008) 16160.

[16] A. Erdem, A. E. Eroglu, Speciation and preconcentration of inorganic antimony in waters by

Duolite GT-73 microcolumn and determination by segmented flow injection-hydride

generation atomic absorption spectrometry (SFI-HGAAS), Talanta 68 (2005) 86.

[17] S.L.C. Ferreira, W.N.L. dos Santos, M.A. Bezerra, V.A. Lemos, J.M. Bosque-Sendra, Use of

factorial design and doehlert matrix for multivariate optimisation of an on-line

preconcentration system for lead determination by flame atomic absorption spectrometry,

Anal. Bioanal. Chem. 375 (2003) 443.

[18] Y. Li, Y. Jiang, X.P. Yan, W.J. Peng, Y.Y. Wu, A flow injection on-line multiplexed

sorption preconcentration procedure coupled with flame atomic absorption spectrometry for

determination of trace lead in water, tea, and herb medicines, Anal. Chem. 74 (2002)1075.

[19] D.L. Tsalev, L. Lampugnani, R. Georgieva, K. Chakar-ova, K. J. Petrov, Electrothermal

atomic absorption spectrometric determination of cadmium and lead with stabilized

phosphate deposited on permanently modified platforms, Talanta 58 (2002) 331.

[20] L.F. Dias, G.R. Miranda, T.D. Saint’Pierre, S.M. Maia, V.L.A. Frescura, A. Curtius, Method

development for the determination of cadmium, copper, lead, selenium and thallium in

sediments by slurry sampling electrothermal vaporization inductively coupled plasma mass

spectrometry and isotopic dilution calibration, J. Spectrochim. Acta B. 60 (2005) 117.

[21] Y.K. Lu, H.W. Sun, C.G. Yuan, X.P. Yan, Simultaneous determination of trace cadmium and

arsenic in biological samples by hydride generation-double channel atomic fluorescence

spectrometry, Anal. Chem. 74 (2002) 1525.

[22] H. Zheng, Z. Yan, H. Dong, B. Ye, Simultaneous determination of lead and cadmium at a

glassy carbon electrode modified with Langmuir–Blodgett film

of p-tert-butylthiacalix[4]arene, Sens. Actuat. B 120 (2007) 603; Y. Wang, Y. H. Wang, Z.L.

Fang, Octadecyl immobilized surface for precipitate collection with a renewable

microcolumn in a lab-on-valve coupled to an electrothermal atomic absorption spectrometer

for ultratrace cadmium determination, Anal. Chem. 77 (2005) 5401.

[23] X. Lin, R.C. Burns, G.A. Lawrance, The effect of electrolyte composition on the

precipitation of cadmium(II) using lime and magnesia, Water, Air, & Soil Pollution.165

(2005) 131-152.

[24] S.R. Younesi, H. Alimadadi, E.K. Alamdari, S.P.H. Marashi, Kinetic mechanisms of

cementation of cadmium ions by zinc powder from sulfate solutions. Hydrometallurgy 84

(2006) 155–164.

[25] B.R. Reddy, D.N. Priya, K.H. Park, Separation and recovery of cadmium(II), cobalt(II) and

nickel(II) from sulfate leach liquors of spent Ni-Cd batteries using phosphorus based

extractants. Sep. Puri. Technol. 50 (2006) 161-166.

[26] S. Kocaoba, Comparison of Amberlite IR 120 and dolamite’s performance for the removal of

heavy metals. J. Hazard. Mater.147 (2007) 488-496.

[27] R. H. Mortaheb, H. Kosuge, B. Mokhtarani, M.H. Amini, H.R. Banihashemi, Study on

removal of cadmium from wastewater by emulsion liquid membrane. J. Hazard. Mater.165

(2009) 630–636.

[28] S. Congeevaram, S. Dhanarani, J. Park, M. Dexilin, K. Thamaraiselvi, Biosorption of

chromium and nickel by heavy metal resistant fungal and bacterial isolates, J. Hazard. Mater.

146 (2007) 270; H.L. Liu, B.Y. Chen, Y.W. Lan, Y.C. Cheng, Biosorption of Zn(II) and

Cu(II) by the indigenous Thiobacillus thiooxidans, Chem. Eng. J. 97 (2004) 195.

[29] G. M. Gadd, Microbial Mineral Recovery, McGraw-Hill: New York, 1990, pp 249.

Page 10 of 18

11

[30] C. Huang, C.P. Huang, Application of aspergillus oryzae and rhizopus oryzae for cu(ii)

removal, Water Res. 30 (1996) 1985.

[31] D.M. Veneu, G. A.H. Pino, M.L. Toremb, T.D. Saint Pierre, Biosorptive removal of

cadmium from aqueous solutions using a streptomyces lunalinharesii strain, Minerals Eng.

29 (2012) 112.

[32] C.-F.Yang, H.-M. Shen, Y. Shen, Z.-X Zhuang and C.-N. Ong, Cadmium-induced oxidative

cellular damage in human fetal lung fibroblasts (MRC-5 Cells), Environ. Health Perspect.

105 (1997) 712–716; H. Hayakawa, A. Taketomi, K. Sakumi, M. Kuwano, M. Sekiguchi,

generation and elimination of 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate, a

mutagenic substrate for dna synthesis, in human cells, Biochemistry 34 (1995) 89.

[33] A. Catte, F. Cesare-Marincola, J. R. C.van derMaarel, G. Saba, A. Lai, Binding of Mg2+

,

Cd2+

, and Ni2+

to liquid crystalline NaDNA:  polarized light microscopy and NMR

investigations, Biomacromolecules 5 (2004) 1552; L. RulíSek, J. Sponer, Outer-shell and

inner-shell coordination of phosphate group to hydrated metal ions (Mg2+

, Cu2+

, Zn2+

, Cd2+

)

in the presence and absence of nucleobase. The Role of Nonelectrostatic Effects, J. Phys.

Chem. B 107 (2003) 1913.

[34] M. V. Mikhailova, N. A. Littlefield, B. S. Hass, L. A. Poirier, M. W. Chou,

Cadmium-induced 8-hydroxydeoxyguanosine formation, DNA strand breaks and antioxidant

enzyme activities in lymphoblastoid cells, Cancer Lett. 115 (1997) 141.

[35] S. Pal, J. Y. Kim, S. H. Park, H. B. Lim, K-H. Lee, J. M. Song, Quantitative classification of

DNA damages induced by submicromolar cadmium using oligonucleotide chip coupled with

lesion-specific endonuclease digestion, Environ. Sci. Technol. 45 (2011) 4460.

[36] K.S. Low, C.K. Lee, S.C. Liew, Sorption of cadmium and lead from aqueous solutions by

spent grain, Process Biochem. 36 (2000) 59; Y.S. Ho, C.C. Wang, Pseudo-isotherms for the

sorption of cadmium ion onto tree fern, Process Biochem. 39 (2004) 759; V. Gomez-

Serrano, Adsorption of mercury, cadmium and lead from aqueous solution on heat-treated

and sulfurized activated carbon, Water Res. 32 (1998) 1; M. S. Polo, R. Utrialla,

Adsorbent-adsorbate interactions in the adsorption of Cd(II) and Hg(II) on ozonized

activated carbons, Environ. Sci. Technol. 36 (2002) 3850; S. Al- Asheh, Z.

Duvnjak, Sorption of cadmium and other heavy metals by pine bark, J. Hazard. Mater. 56

(1997) 35; M. Singanan, Removal of lead(II) and cadmium(II) ions from wastewater using

activated biocarbon, Science Asia 37 (2011)115; J.P. Cazón, M. Viera, E. Donati and E.

Guiba, Zinc and cadmium removal by biosorption on Undaria pinnatifida in batch and

continuous processes, J. Environ. Manage. 129 (2013) 423-434.

[37] S. A. Churchill, R. A. Griffin, P. A. Jones, P. F. Churchill, Biodegradation rate enhancement

of hydrocarbons by an oleophilic fertilizer and a rhamnolipid biosurfactant, J. Environ. Qual.

24 (1995) 19; Y. Zhang, R.M. Miller, Effect of rhamnolipid (biosurfactant) structure on

solubilization and biodegradation of n-alkanes, Appl. Environ. Microbiol. 61 (1995) 2247; D.

C. Herman, J. F. Artiola, R.M. Miller, removal of cadmium, lead, and zinc from soil by a

rhamnolipid biosurfactant, Environ. Sci. Technol. 29 (1995) 2280.

[38] A. Bodagh, H. Khoshdast, H. Sharafi, H.S. Zahiri, K.A. Noghabi, Removal of cadmium(II)

from aqueous solution by ion flotation using rhamnolipid biosurfactant as an ion collector,

Ind. Eng. Chem. Res. 52 (2013) 3910.

[39] G. L. Rorrer, T.-Y. Hsien, J. D. Way, Synthesis of porous-magnetic chitosan beads for

removal of cadmium ions from wastewater, Ind. Eng. Chem. Res. 32 (1993) 2170.

[40] E. Guibal, C. Milot, J. M. Tobin, Metal-anion sorption by chitosan beads:  equilibrium and

kinetic studies, Ind. Eng. Chem. Res. 37 (1998) 1454.

[41] S. Hasan, A. Krishnaiah, T. K. Ghosh, D. S. Viswanath, Adsorption of divalent cadmium

(cd(II)) from aqueous solutions onto chitosan-coated perlite beads, Ind. Eng. Chem. Res. 45

(2006) 5066; C. Li, P. Champagne, Fixed-bed column study for the removal of cadmium (II)

and nickel (II) ions from aqueous solutions using peat and mollusk shells, J. Hazardous

Page 11 of 18

12

Mater. 171 (2009) 872; M. Jain, V.K. Garg, K. Kadirvelu, Cadmium (II) sorption and

desorption in a fixed bed column using sunflower waste carbon calcium–alginate beads,

Bioresource Technol. 129 (2013) 242.

[42] L. Wang, X. Tao, J. Shi, X. Yu, M. Jiang, Conjugated chromophore near the

quantum-confined cadmium sulfide cluster: quenched photoluminescence and enhanced

two-photon absorption, J. Phys. Chem. B, 110 (2006) 19711.

[43] R. McRae, P. Bagchi, S. Sumalekshmy, C.J. Fahrni, In situ imaging of metals in cells and

tissues, Chem. Rev. 109 (2009) 4780.

[44] M. Choi, M. Kim, K.D. Lee, K.N. Han, I.A. Yoon, H.J. Chung, J. Yoon, A new reverse pet

chemosensor and its chelatoselective aromatic cadmiation, Org. Lett., 3 (2001) 3455.

[45] S. K. Kim, J. H. Lee, J. Yoon, Bull. Korean Chem. Soc. 24 (2003) 1032.

[46] T. Gunnlaugsson, T. C. Lee, R. Parkesh, Cd(II) sensing in water using novel aromatic

iminodiacetate based fluorescent chemosensors, Org. Lett. 5 (2003) 4065.

[47] L. Prodi, M. Montalti, N. Zaccheroni, J.S. Bradshaw, R.M. Izatt, P.B. Savage,

Characterization of 5-chloro-8-methoxyquinoline appended diaza-18-crown-6 as a

chemosensor for cadmium, Tetrahedron Lett. 42 (2001)2941.

[48] R.T. Bronson, D.J. Michaelis, R.D. Lamb, G.A. Husseini, P.B. Farnsworth, M.R. Linford,

R.M. Izatt, J.S. Bradshaw, P.B. Savage, Efficient immobilization of a cadmium chemosensor

in a thin film:  generation of a cadmium sensor prototype, Org. Lett. 7 (2005) 1105.

[49] C. Lu, Z. Xu, J. Cui, R. Zhang, X.J. Qian, Ratiometric and highly selective fluorescent sensor

for cadmium under physiological pH range:  a new strategy to discriminate cadmium from

zinc, Org. Chem. 72 (2007) 3554.

[50] X. Tang, X. Peng, W. Dou, J. Mao, J. Zheng, W. Qin, W. Liu, J. Chang, X. Yao, Design of a

semirigid molecule as a selective fluorescent chemosensor for recognition of Cd(II), Org.

Lett., 10 (2008) 3653.

[51] M. Soibinet, V. Souchon, I. Leray, B.J. Valeur, Rhod-5N as a fluorescent molecular sensor of

cadmium(II) ion, J. Fluoresc. 18 (2008)1077.

[52] G.M. Cockrell, G. Zhang, D.G. VanDerveer, R.P. Thummel, R.D.J. Hancock, Enhanced

metal ion selectivity of 2,9-di-(pyrid-2-yl)-1,10-phenanthroline and its use as a fluorescent

sensor for cadmium(II), J. Am. Chem. Soc. 130 (2008) 1420.

[53] Y. Zhou, Y. Xiao, X. Qian, A highly selective Cd2+

sensor of naphthyridine: fluorescent

enhancement and red-shift by the synergistic action of forming binuclear complex,

Tetrahedron Lett. 49 (2008) 3380.

[54] Y.M. Zhang, Y. Chen, Z. Li, N. Li, Y. Liu, Quinolinotriazole-beta-cyclodextrin and its

adamantanecarboxylic acid complex as efficient water-soluble fluorescent Cd(II) sensors,

Bioorg. Med. Chem. 18 (2010) 1415.

[55] L. Xue, G. Li, Q. Liu, H. Wang, C. Liu, X. Ding, S. He, H. Jiang, Ratiometric fluorescent

sensor based on inhibition of resonance for detection of cadmium in aqueous solution and

living cells, Inorg. Chem. 50 (2011) 3680.

[56] X. Zhou, P. Li, Z. Shi, X. Tang, C. Chen, W. Liu, A highly selective fluorescent sensor for

distinguishing cadmium from zinc ions based on a quinoline platform, Inorg. Chem. 51

(2012) 9226.

[57] M. A. Palacios, Z. Wang, V. A. Montes, G. V. Zyryanov, B. J. Hausch, K. urs kov ,

Hydroxyquinolines with extended fluorophores: arrays for turn-on and ratiometric sensing of

cations, Chem. Commun. 31 (2007) 3708; M. A. Palacios, Z. Wang, V. A. Montes, G. V.

Zyryanov, P. Anzenbacher, Rational design of a minimal size sensor array for metal ion

detection, J. Am. Chem. Soc. 130 (2008) 10307; S. Jana, S. Dalapatia, Md. A. Alam, N.

Guchhait, Fluorescent chemosensor for Zn(II) ion by ratiometric displacement of Cd(II) ion:

A spectroscopic study and DFT calculation, J. Photochem. Photobiol. A 238 (2012) 7-15.

[58] A. Fragoso, M. Ortiz, B. Sanroma, C. K. O’Sullivan, Multilayered catalytic biosensor

self-assembled on cyclodextrin-modified surfaces, J. Incl. Phenom. Macrocycl. Chem. 2011,

Page 12 of 18

13

69, 355; Y. Li, J. Zhou, C. Liu and H. Li, Composite quantum dots detect Cd(II) in living

cells in a fluorescence “turning on” mode, . Mater. Chem. 22 (2012) 2507.

[59] Y.-M. Zhang, Y. Chen, Z.-Q. Li, N. Li and Y. Liu, Quinolinotriazole-β-cyclodextrin and its

adamantanecarboxylic acid complex as efficient water-soluble fluorescent Cd2+

sensors,

Bioorg. Med. Chem. 18 (2010) 1415.

[60] S. Y. Park, J. H. Yoon, C. S. Hong, R. Souane, J. S. Kim, S. E. Matthews and J. Vicens, A

pyrenyl-appended triazole-based calix[4]arene as a fluorescent sensor for Cd2+

and Zn2+

, J.

Org. Chem. 73 (2008) 8212.

[61] Y. Tharakeswar, Y. Kalyan, B. Gangadhar, K.S. Kumar, G.R. Naidu, Optical chemical

sensor for screening cadmium (II) in natural waters, J. Sensor Technol. 2 (2012) 68.

[62] A.A. Ensafi, Z.N. Isfahani, A simple optical sensor for cadmium ions assay in water samples

using spectrophotometry, J. Anal. Chem. 66 (2011) 151.

[63] A. A. Ensafi, S. Meghdadi, E. Fooladgar, Development of a new selective optical sensor for

cadmium monitoring, IEEE Sensor J. 8 (2008) 1794.

[64] R. Czolk, J. Reichert, H.J. Ache, An optical sensor for the detection of heavy metal ions,

Sens. Actuat. B 7 (1992) 540.

[65] B. Kuswandi, A.A. Vaughan, R. Narayanaswamy, Simple regression model using an optode

for the simultaneous determination of zinc and cadmium mixtures in aqueous samples, Anal.

Sci. 17 (2001) 181.

[66] D. Prabhakaran, M. Yuehong, H. Nanjo, H. Matsunaga, Naked-eye cadmium sensor:  using

chromoionophore arrays of Langmuir−Blodgett molecular assemblies, Anal. Chem. 79

(2007) 4056.

[67] L. Feng, X. Li, H. Li, W. Yang, L. Chen, Y. Guan, Enhancement of sensitivity of

paper-based sensor array for the identification of heavy-metal ions, Anal. Chim. Acta 780

(2013) 74.

[68] K. L. Wustholz, A. I. Henry, J. M. McMahon, R. G. Freeman, N. Valley, M. E. Piotti, M. J.

Natan, G. C. Schatz, R. P.Van Duyne, Structure−activity relationships in gold nanoparticle

dimers and trimers for surface-enhanced raman spectroscopy, J. Am. Chem. Soc. 132 (2010)

10903.

[69] J. Yin, T. Wu, J. Song, Q. Zhang, S. Liu, R. Xu, H. Duan, SERS-active nanoparticles for

sensitive and selective detection of cadmium ion (Cd2+

), Chem. Mater. 23(2011) 4756; A J.

Wang, H. Guo, M. Zhang, D. L. Zhou, R. Z. Wang, J. J. Feng, Sensitive and selective

colorimetric detection of cadmium(II) using gold nanoparticles modified with

4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, Microchim.Acta 180 (2013) 1051.

[70] Y. Wu, S. Zhan, L. Wang, P. Zhou, Selection of a DNA aptamer for cadmium detection

based on cationic polymer mediated aggregation of gold nanoparticles, Analyst 139 (2014)

1550-1561. [71] S. C. C. Monterroso, H. M. Carapuça, J. E. J. Simão, A. C. Duarte, Optimisation of mercury

film deposition on glassy carbon electrodes: evaluation of the combined effects of pH,

thiocyanate ion and deposition potential, Anal. Chim. Acta 503 (2004) 203; H. M. Carapuc,

S. C. C. Monterroso, L. S. Rocha, A. C. Duarte, Simultaneous determination of copper and

lead in seawater using optimised thin-mercury film electrodes in situ plated in thiocyanate

media, Talanta 64 (2004) 566.

[72] M. Khairy, R.O. Kadara, D. K. Kampouris, C. E. Banks, In situ bismuth film modified screen

printed electrodes for the bio-monitoring of cadmium in oral (saliva) fluid, Anal. Method. 2

(2010) 645.

[73] H. Bagheri, A. Afkhami, H. Khoshsafar, M. Rezaei, A. Shirzadmehr, Simultaneous

electrochemical determination of heavy metals using a triphenylphosphine/MWCNTs

composite carbon ionic liquid electrode, Sen. Actuat. B 186 (2013) 451.

Page 13 of 18

14

[74] R. G. Kempegowd, P. Malingappa, A binderless, covalently bulk modified electrochemical

sensor: Application to simultaneous determination of lead and cadmium at trace level, Anal.

Chim. Acta 728 (2012) 9.

[75] S. Senthilkumar, R. Saraswathi, Electrochemical sensing of cadmium and lead ions at

zeolite-modified electrodes: Optimization and field measurements, Sen. Actuat. B 141 (2009)

65.

[76] H. Zheng, Z. Yan, H. Dong, B. Ye, Simultaneous determination of lead and cadmium at a

glassy carbon electrode modified with Langmuir–Blodgett film

of p-tert-butylthiacalix[4]arene, Sen. Actuat. B 120 (2007) 603; A.A. Argun, A. M. Banks, G.

Merlen, L.A. Tempelman, M.F. Becker, T. Schuelke, B.M. Dweik, Highly sensitive detection

of urinary cadmium to assess personal exposure, Anal. Chim. Acta 773 (2013) 45.

[77] Ping L.u., Q. Feng, Q. Meng, T. Yuan, Electrokinetic remediation of chromium- and

cadmium-contaminated soil from abandoned industrial site, Sep. Purif. Technol. 98 (2012)

216; M. Karimi, F. Aboufazeli, H. R. L. Z. Zhad, O. Sadeghi, E. Najafi, Determination of

Cadmium (II) Ions in Environmental Samples : A Potentiometric Sensor, Curr. World Env. 7

(2012) 201.

[78] J. Almeira O., C-S. Peng, A. Abou-Shady, Simultaneous removal of cadmium from kaolin

and catholyte during soil electrokinetic remediation, Desalination 300 (2012) 1.

[79] S. A. El-Safty, T. Hanaoka, Microemulsion liquid crystal templates for highly ordered

three-dimensional mesoporous silica monoliths with controllable mesopore structures, Chem.

Mater.16 (2004) 384.

[80] S. A. El-Safty, F. Mizukami, T. Hanaoka, general and simple approach for control cage and

cylindrical mesopores, and thermal/hydrothermal stable frameworks, J. Phys. Chem. B. 109

(2005) 9255-9264.

[81] S. A. El-Safty, F. Mizukami, T. Hanaoka, Transparent

cubic Fd3m mesoporous silica monoliths with highly controllable pore architectures, J. Mater.

Chem. 15 (2005) 2590 – 2598.

[82] S. A. El-Safty, T. Hanaoka, F. Mizukami, Design of highly stable, ordered cage

mesostructured monoliths with controllable pore geometries and sizes, chem. mater. 17

(2005) 3137.

[83] S. A. El-Safty, T. Hanaoka, F. Mizukami, Large-scale design of cubic Ia3d mesoporous silica

monoliths with high order, controlled pores, and hydrothermal stability, Adv. Mater. 17

(2005) 47; S. A. El-Safty, Designs for size-exclusion separation of macromolecules by

densely-engineered mesofilters,TrAC-Trend. Anal. Chem., 30 (2011) 447-458.

[84] S. A. El-Safty, T. Hanaoka, F. Mizukami, stability of highly ordered nanostructures with

uniformly cylindrical mesochannels, Acta Mater. 54 (2006) 899.

[85] M. Khairy, S. A. El-Safty, M. A. Shenashen, E. A. Elshehy, Hierarchical inorganic–organic

multi-shell nanospheres for intervention and treatment of lead-contaminated blood,

Nanoscale 5 (2013) 7920-7927.

[86] M.A. Shenashen, E.A. Elshehy, S. A. El-Safty, M. Khairy, Visual monitoring and removal of

divalent copper, cadmium, and mercury ions from water by using mesoporous cubic Ia3d

aluminosilica sensors, Sep. Purif. Technol. 116 (2013) 73-86.

[87] M.A. Shenashen, S.A. El-Safty, E.A. Elshehy, Architecture of optical sensor for recognition

of multiple toxic metal ions from water, J. Hazard. Mater. 260 (2013) 833-843.

[88] S.A. El-Safty, M.A. Shenashen, Optical mesosensor for capturing of Fe(III) and Hg(II) ions

from water and physiological fluids, Sens. Actuat. B. 183 (2013) 58-70.

[89] S. A. El-Safty, D. Prabhakaran, A.A. Ismail, H. Matsunaga, F. Mizukam, Nanosensor design

packages: A smart and compact development for metal ions sensing responses, Adv. Funct.

Mater. 17 (2007) 3731.

[90] S. A. El-Safty, M.A. Shenashen, Mercury-ion optical sensors, Trac-Trend Anal. Chem. 38

(2012) 98.

Page 14 of 18

15

[91] T. Balaji, S. A. El-Safty, H Matsunaga, T. Hanaoka, F. Mizukami, Optical sensors based on

nanostructured cage materials for the detection of toxic metal ions, Angew. Chem. Int. Ed.,

45 (2006) 7202.

[92] S. A. El-Safty, M.A. Shenashen, M. Khairy, Optical detection/collection of toxic Cd(II) ions

using cubic Ia3d aluminosilica mesocage sensors, Talanta 98 (2012) 69.

[93] S.A. El-Safty, D. Prabhakaran, Y. Kiyozumi, F. Mizukami, Nanoscale membrane strips for

benign sensing of Hg (II) ions: a route to commercial waste treatments, Adv. Funct. Mater.

18 (2008) 1739.

[94] S. A. El-Safty, A. A. Ismail, H. Matsunaga, T. Hanaoka, F. Mizukami, Optical Nanoscale

Pool-on-Surface Design for Control Sensing Recognition of Multiple Cation, Adv. Funct.

Mater. 18 (2008) 1485.

[95] S.A. El-Safty, M. A. Shenashen, M. Ismael, M. Khairy, Md. R. Awual, Mesoporous

aluminosilica sensors for the visual removal and detection of Pd(II) and Cu(II) ions, Micro.

Mesop. Mater. 166 (2013) 195.

[96] S.A. El-Safty, M.A. Shenashen, M. Khairy, M. Ismeal, Encapsulation of proteins into tunable

and giant mesocage alumina, Chem. Commun. 48 (2012) 6708.

[97] S.A. El-Safty, M.A. Shenashen, M. Khairy, M. Ismeal, Mesocylindrical aluminosilica

monolith biocaptors for size-Selective macromolecule cargos, Adv. Funct. Mater. 22 (2012)

3013- 3021.

[98] S.A. El-Safty, A. Shahat, K. Ogawa, T. Hanaoka, Highly ordered, thermally/hydrothermally

stable cubic Ia3d aluminosilica monoliths with low silica in frameworks, Micro. Meso. Mater.

138 (2011) 51.

[99] S.A. El-Safty, M. Khairy, M. Ismeal, Visual detection and revisable supermicrostructure

sensor systems of Cu (II) analytes, Sens. Act. B. Chem. 166 (2012) 253.

[100] S.A. El-Safty, A. Shahat, Md.R. Awual, Efficient adsorbents of nanoporous aluminosilicate

monoliths for organic dyes from aqueous solution, J. Colloid Interface Sci. 359 (2011) 9.

[101] S.A. El-Safty, A. Shahat, M. Ismael, Mesoporous aluminosilica monoliths for the adsorptive

removal of small organic pollutants, J. Hazard. Mater. 201 (2012) 23; E. B. Sandell,

Colorimetric determination of traces of metals, 3rd ed., Inter-science Publisher, INC., NY,

1959, pp. 326.

[102] S. A. El-Safty, M. A. Shenashen, A. A. Ismail, A multi-pH-dependent, single optical

mesosensor/captor design for toxic metals, Chem. Commun. 48 (2012) 9652; Y.-M. Zhang,

Y. Chen, Z.-Q. Li, N. Li, Y. Liu, Quinolinotriazole-β-cyclodextrin and its

adamantanecarboxylic acid complex as efficient water-soluble fluorescent Cd2+

sensors, Bioorgan. Med. Chem. 18 (2010) 1415.

Page 15 of 18

16

Captions Fig. 1. General approaches to detection and removal of cadmium from the environment.

Fig. 2. (A) Structure of the sensing probe, (B) the four protecting polymers of the sensing probe, (C)

detection of Cd2+ ions, and (D) visible color-transition pattern observed in glass substrates with increasing

concentrations of cadmium ions (pH 7.5, 10 min, 40°C) and an image of the sensor depicting instant

regeneration from cadmium complexes, with 0.1 M HCl.

Fig. 3. The design of enrichment-based pyridylazo compounds array paper (A, B, and C) and the

color-difference maps (“fingerprint”) of cadmium ions at a concentration of 50 μM. For display purposes, the

color ranges of these difference maps are expanded from 4 bits to 8 bits per color (RGB range 4–35 expanded

to 0–255).

Fig. 4. (A) Cd2+

-induced colorimetric responses of AHMT-AuNPs, (B) photographs of AHMT-AuNPs in the

presence of different metal ions (0.24 μM), and (C) colorimetric images of AHMT-AuNPs with different

concentrations of Cd2+

and their corresponding UV-vis spectra after an incubation time of 15 min.

Fig. 5. (A) 3-D model and (B) cross-sectional view of the electrokinetic cell.

Fig. 6. (A) Optical mesosensors for the Cd2+

-ion detection by the direct immobilization approach conducted

by immobilizing hydrophobic DTAR and DPAP probe molecules into HOM, Formation of positively-charged

islands (B) and negatively charged islands (C), and (D) the corresponding UV-vis spectroscopic and

color-map responses of optical sensors fabricated by immobilizing (a) DTAR, (b) DPAP, (c) DPC, and (d)

TMPyP into HOM-cage monolithic carriers, after identifying Cd2+

-analyte ions.

Table 1.

Chemical receptors used for Cd (II) detection

No Chemical formula Kd /M-1 *

Medium Ref.

1 N

N

HOOC

HOOC

COOH

COOH

6.91× 104 pH 10, 0.1 M CAPS

buffer

[60]

2

N

N

COOH

COOH

HOOC

HOOC

pH 7, 0.1 M HEPES

buffer

[61]

3 N

COOK

KOOC

7.9× 103 pH 7.4, HEPES

buffer

[62]

4 N

NKOOC

KOOC

COOK

COOK

1.58 × 104 pH 7.4, HEPES

buffer

[62]

Page 16 of 18

17

5

NH3CO

Cl

NOCH3

Cl

OO

N

N

OO

1.26 × 106

1.99 × 104

methanol solution

pH 7.4, water

[63]

6

O

NHO

CH3

CH3

O

OH

O

CH3

NOCH3

Cl

NH3CO

Cl

OO

NN

OO

n

1.25 ×106 pH 5.1, 0.01 M

Sodium acetate

buffer

[64]

7

N

NH

NH

O

O CH3

N

N

N

5.76 × 105 pH 7.2,

ethanol-water

solutions (1:9, v/v,

50 mM HEPES

buffer)

[65]

8

N

OO

N N

O

N

7.9×108 pH 7,

methanol-water

solutions (95:5, v/v,

10mM

HEPES-buffered)

[66]

9

N

N

NN

N

N

NH

CH3

CH3

CH3

2.19 ×105 pH7, ethanol and

water (4:6, v/v) pH

adjusted by 75%

HClO4 or 10%

CH3)4N+OH

[69]

10

2.3 ×103 pH 7.2, HEPES

buffer solution

10 mM.

[70]

11

N

N

N

N

O

CH3

CH3

O

CH3

N

CH3

CH3

4.1 x 1011

pH 7.4, 10 mM

HEPES, 0.1 M

NaCl.

[71]

12 N

NHO

NO

9.8 × 105 Ethanol. [72]

13 N

N

N

N

NN

7.9 ×104

0.11 ×104

Acetonitrile

Tetrahydrofuran

[74]

N

ONN N

CH3

Page 17 of 18

18

14

NOO

CH3

NHNH

N NH2

N

1.62×1010

pH 7.2, 50 mM

HEPES

[13]

15

N

N+

CH3

B-

F

F

CH3

CH3

CH3

N

N

N

7.0 ×105 pH 7.4, acetone /

water mixture ( 9/1

v/v, 0.01 M

Tris-HCl

[14]

16

NNHOH

O

O NH

OH

H

N

NH

OH

O

O

NHOH

H

N

N+B

-F

F

CH3CH3

CH3

CN

1.3×105 pH 7.5, 0.1 mM

sodium phosphate

[15]

*Kd is association constant

Page 18 of 18