Research ArticleFabricationofCeramsiteAdsorbent fromIndustrialWastes for theRemoval of Phosphorus from Aqueous Solutions

Yue Yin ,1 Gaoyang Xu ,1 Linlin Li ,1 Yuxing Xu ,1 Yihan Zhang ,1

Changqing Liu ,1 and Zhibin Zhang2

1School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China2School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, China

Correspondence should be addressed to Changqing Liu; lcqlfyqut@126.com

Received 4 July 2020; Revised 21 September 2020; Accepted 6 October 2020; Published 26 October 2020

Academic Editor: Leonardo Palmisano

Copyright © 2020 Yue Yin et al.*is is an open access article distributed under the Creative Commons Attribution License, whichpermits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

A more applicable adsorbent was fabricated using industrial wastes such as red mud, fly ash, and riverbed sediments. *e heavymetal inside the raw materials created metal hydroxy on the adsorbent surface that offered elevated adsorption capacity forphosphorus.*e required equilibrium time for the adsorption is only 10min.*e theoretical maximum adsorption capacity of theadsorbent was 9.84mg·g−1 inferred from the Langmuir adsorption isotherm. Higher solution pH favored phosphorus adsorption.Kinetics study showed that the adsorption could be better fitted by the pseudo-second-order kinetic model. *e presence ofcoexisting anions had no significant adverse impact on phosphorus removal.*e speciation of the adsorbed phosphorus indicatedthat the adsorption to iron and aluminum is the dominating adsorption mechanism. Moreover, a dynamic adsorption columnexperiment showed that, under a hydraulic time of 10min, more than 80% of the phosphorus in the influent was removed and thesurplus phosphorus concentration was close to 0.1mg L−1. *e water quality after adsorption revealed its applicability in realtreatment. Consequently, the adsorbent synthesized from industrial wastes is efficient and applicable due to the high efficiency ofphosphorus removal and eco-friendly behavior in solutions.

1. Introduction

Wastewater discharging to water bodies such as rivers andlakes will deteriorate the water quality. Phosphorus is one ofthe most influential pollutants in wastewater, and excessivephosphorus leads to eutrophication [1]. Eutrophication hasbecome a serious environmental problem worldwide as it isaccompanied by rapid overgrowth of algae which will depletethe oxygen in the water and suffocate the aquatic animals[2, 3]. In addition, phosphorus scarcity is another trouble-some issue, mined rock phosphate is the major source ofphosphorus, and the existing mine rock phosphate will be-come exhausted in less than 100 years [4]. In wastewatertreatment, most of the technologies are designed only fol-lowed by the wastewater discharge threshold without thepurpose of phosphorus recovery, but in China, approximately1378 t of phosphorus was discharged directly without anyrecycling in 2018 (http://www.mohurd.gov.cn/csjs/xmzb/

index.htm). In order to recover the phosphorus for reusesimultaneously, it is urgent to develop new technologies thatcould remove the phosphorus in the wastewater completelyand recover the phosphorus resource. *e application ofproper adsorbents could be one of the solutions to meet therequirements [5–7]. Several reports have investigated theability of phosphorus removal and recovery of different ad-sorbents [8, 9]. For example, rare earth element lanthanumand graphene were used as materials of adsorbents because oftheir high phosphate attention capability [10, 11]. *e cal-culated adsorption capacity was higher than most of the low-cost adsorbents. However, the cost of the adsorbents such aslanthanum-based and graphene-based adsorbents is notmentioned, but considering its high-price raw materials andcomplicated fabrication synthesis process, the cost will beunacceptable in wastewater treatment. Furthermore, the spentadsorbents need further disposal. Consequently, these dis-advantages hinder practical applications.

HindawiJournal of ChemistryVolume 2020, Article ID 8036961, 13 pageshttps://doi.org/10.1155/2020/8036961

mailto:lcqlfyqut@126.comhttp://www.mohurd.gov.cn/csjs/xmzb/index.htmhttp://www.mohurd.gov.cn/csjs/xmzb/index.htmhttps://orcid.org/0000-0001-6309-8605https://orcid.org/0000-0003-2709-1136https://orcid.org/0000-0003-1851-693Xhttps://orcid.org/0000-0003-3719-6396https://orcid.org/0000-0003-4004-094Xhttps://orcid.org/0000-0002-6114-3238https://creativecommons.org/licenses/by/4.0/https://doi.org/10.1155/2020/8036961

In the past decades, the adsorbents made from haz-ardous materials have gained great concerns because of itsremoval capacity of anionic pollutants and low cost. Manyliterature studies have reported the use of fly ash [12], redmud [13], tailings [14], and blast furnace slag [15] tomanufacture ceramsite adsorbents to remove phosphorusfrom aqueous solutions. Wang et al. [12] reported aphosphorus adsorption comparison among red mud, flyash, ferric-alum water treatment residual, and theirmodified materials, and the results demonstrate that theiron-modified materials were better than HCl-modifiedmaterials, and ferric-alum water treatment residual wasbetter than red mud and fly ash. Another research byTangde et al. [16] investigated the phosphate adsorptiononto activated red mud, and the results indicated that themaximum adsorption capacity of activated red mud was112.36mg·g−1 at optimum pH 2. However, to the best of theauthors’ knowledge, no literature is mixing contaminatedriverbed sediments with red mud and fly ash to fabricateceramsite adsorbent. For one thing, the riverbed sedimentsare in a great amount of silicon which is the main com-ponent for producing ceramsite, the clay used in the past isexhausting in earth, and replacing clay with riverbedsediments can be prompted in construction and watertreatment works [17]. In addition, the incineration processwill stabilize the heavy metal inside the riverbed sedimentsand reduce the heavy metal leaching which favored itspractical application.

In Shandong province, China, the heavy industry ac-counts for a large proportion which caused too much in-dustrial wastes such as redmud and fly ash [18]. On the otherhand, river pollution is not peculiar in Shandong, and manyrivers were polluted at different levels. With the effort thegovernment made in recent years, the water in rivers is nowless polluted or unpolluted; nevertheless, the sediments onthe riverbed have been compromised due to long-termcontamination. *is large amount of the sediments cannotbe treated only by in situ solidification because most of thesediments are active and unable to be repaired easily. In thisstudy, fly ash and red mud were added into contaminatedriverbed sediments to fabricate ceramsite. Hence, usingthese waste materials to manufacture ceramsite will stabilizethe pollutants inside, effectively lower the ecological risk ofthe waste, and utilize the elements present in the waste tostrengthen the adsorption capacity.

*e objective of this study is to investigate the feasibilityof “use the waste to treat the waste,” and in other words, theadsorption capacity of ceramsite made from the combina-tion of red mud, fly ash, and contaminated riverbed sedi-ments. To meet the real application, the adsorption time inthis study was set at 10minutes while the equilibrium time inother research studies ranged from 0.5 to 48 hours. Also, thepH in every experiment (except for pH study) was set at 7 tobe more representative. Kinetic and adsorption isothermwere investigated to analyze the adsorption process, alongwith the effect of pH, coexisting anions, and dosage. *especiation of the adsorbed phosphorus was further inves-tigated to characterize the adsorption mechanism. For theapplication of ceramsite, the real wastewater adsorption,

dynamic column adsorption, and desorption experimentswere also elucidated.

2. Materials and Methods

2.1. Materials. All chemicals used in this study were ofanalytical grade purchased from Sinopharm Chemical Re-agent Co., Ltd. All data were triplicated, the values wereaveraged, and the relative standard deviations were below8% in all values.*e red mud and fly ash were obtained fromthe industry in Shandong province. *e heavy metal con-taminated riverbed sediment was sampled from a heavy-polluted river located in Shandong province. *e chemicaland mineral compositions of the raw materials used in thisresearch are given in Table 1 and Figure 1, respectively.Deionized water was used in this study.

2.2. Synthesis of Ceramsite. Raw materials were air-dried for10 days to remove moisture and then ground to pass a 48-mesh sieve. *e riverbed sediment, fly ash, red mud, andsawdust were mixed at 5 : 3 :1 : 1 (w/w) and deionized waterwas added (20 wt%). *e mixture was ground into pellets(diameter: 8–10mm) and dried at 105°C for 4 hours in anoven. *e origin pellets were incinerated in a muffle furnaceat 900°C for 1 hour with a ramp at 10°Cmin−1. *e achievedceramsite was cooled naturally, ground to pass 20-meshsieve (∼1.27mm), and stored in a desiccator for future use.

2.3. Characterization of Ceramsite. *e chemical composi-tion was determined by X-ray fluorescence spectroscopy(XRF-1800, SHIMADZU). Mineralogical detection wascarried out using X-ray diffraction (XRD, Rigaku) using Curadiation (45 kV, 40mA). *e surface morphologies wereexamined by scanning electron microscopy (SU8000,Hitachi). BET surface area was detected by MicromeriticsASAP2460.*e point of zero charge of ceramsite made fromindustrial wastes was tested according to the solid additionmethod [19]. Briefly, each flask contained 0.1 g ceramsite and100mL 0.01M KNO3 solution with pH between 2 and 10and was shaken for 10min to reach equilibrium. *e initialpH was adjusted by using 0.1M HCl and 0.1M NaOH, andthe final pH of the solutions wasmeasured.*e change of thepH value (before and after shaking) was designated as ΔpHwhich was plotted against initial pH, and the pH at the pointof zero charge (pHpzc) value was at the initial pH valuewhereΔpH is equal to zero (where the curve intersects theX-axis) [20].

2.4. Static Adsorption Methods. To study equilibriumphosphorus adsorption capacity, 0.5 g ceramsite was addedinto a conical flask with 50mL of a phosphate concentrationvarying from 1 to 20mgL−1. *e mixture was shaken at120 rpm for 10min in a thermostatic shaker. After that, themixed solution was filtered through a 0.45 μm membraneand the phosphate concentration was detected using themolybdenum-blue complex method. *e phosphorus ad-sorption capacity of ceramsite (qe (mg g−1)) and the removal

2 Journal of Chemistry

rate of the phosphorus (R(%)) were calculated by the fol-lowing equations:

qe �C0 − Ce(

a, (1)

R �C0 − Ce(

C0× 100%, (2)

where C0 (mg·L−1) is the initial phosphorus concentration,Ce (mg·L−1) is the phosphorus concentration at equilibrium,and a (g·L−1) is the adsorbent dosage.

For kinetics studies, 0.5 g ceramsite was added intophosphate solution (concentration� 10, 5, and 2mgL−1),and the mixture was shaken for different times (10 s–600 s)and tested as previously mentioned. For the effect of pH onphosphorus adsorption, phosphorus solutions were pre-pared at different initial pH conditions using 0.1M HCl or0.1M NaOH (phosphorus concentration� 10mg·L−1 andadsorbent dosage� 1 g·L−1) and shaken for 10min at 25°C.In the dosage effect study, different adsorbent dosages wereapplied from 0.5 to 10 g·L−1, mixing with phosphorus so-lutions of 50mg·L−1 and shaking for 10min. To determinethe effect of coexisting anions on phosphorus adsorption, thecompeting coexisting anions such as Cl−, F−, SiO32−, andSO42− were added.

*ere are three kinds of phosphorus adsorbed on theadsorbents, namely, physically adsorbed phosphorus (phys-P), Fe/Al adsorbed phosphorus (Fe/Al-P), and Ca/Mg

adsorbed phosphorus (Ca/Mg-P). To determine the speci-ation of the phosphorus adsorbed on the ceramsite, amodified sequential extraction procedure was used based on[21] after equilibrium (experimental condition: 10min,120 rpm, initial phosphorus concentration� 20mg·L−1, andadsorbent dosage� 5 g·L−1). To be specific, the extractionprocedure is shown in Table 2.

For recyclability of the spent adsorbent, different solu-tions were prepared to conduct desorption experimentsincluding 0.1M NaCl, 0.1M Na2CO3, 0.1M NaOH, 0.1MHCl, and 0.1M H2SO4. *e experiment conditions were asfollows: 10 g·L−1 adsorbent, 50mg·L−1 phosphorus, 10min,and 120 rpm. For real adsorption applications, water sam-ples were collected from different places such as watertreatment plants, wastewater treatment plants, parks, river,and city runoff. Unless otherwise stated, the pH of allphosphate solutions used in this study was adjusted to 7.

2.5. Dynamic Column Adsorption. Dynamic adsorption wasconducted using laboratory-scale adsorption columns. *ecolumns were made from polymethyl methacrylate with aninner diameter of 30mm and a height of 100mm. *ecolumn was packed with 20 g ceramsite with a functionalvolume of 50ml. *e effluent was prepared by dissolvingKH2PO4 with deionized water to achieve different initialconcentrations, and the HRT was maintained at 10min.

3000

2000

1000

0

Relat

ive i

nten

sity

(a.u

.)

0 20 40 60 802-theta (degrees)

HematiteChabaziteCalcite

(a)

Relat

ive i

nten

sity

(a.u

.)

60000

50000

40000

30000

20000

10000

00 20 40 60 80

2-theta (degrees)

GypsumCocsite

(b)

Figure 1: XRD spectra of (a) red mud and (b) fly ash.

Table 1: Chemical compositions of raw materials (% by mass).

SiO2 Al2O3 CaO Fe2O3 SO3 Na2O TiO2Riverbed sediment 56.58 14.52 13.29 6.68 1.00 1.02 0.88Red mud 20.86 22.40 3.73 36.00 0.52 10.46 5.00Fly ash 1.55 0.72 44.60 0.23 52.47 0.23 NDND�not detected.

Journal of Chemistry 3

3. Results and Discussion

3.1. Characterization of Ceramsite. XRD patterns of the rawmaterials and the adsorbent before and after adsorption aregiven in Figures 1 and 2. As from Figure 1(a), the crystallinephases of the raw red mud are identified as hematite,chabazite, and calcite. Figure 1(b) shows that the mainmineral compositions of fly ash are gypsum and coesite. *eiron, aluminum, silicon, and calcium present in the red mudand fly ash support the structure of the adsorbent andfunction as the major activated site to adsorb phosphorus.*e XRD pattern of adsorbent before and after adsorption isdepicted in Figure 2, and it can be seen that the adsorbenthas a stable crystalline structure comparing to raw materials.Additionally, no obvious change is observed in the XRDpattern after adsorption indicates its great stability forphosphorus adsorption in aqueous solutions.

Figure 3 shows the morphology of ceramsite adsorbentwith SEM which confirms the porous surface of the ad-sorbent. *is heterogeneous surface will increase theadsorption capacity due to its higher specific surface area;meanwhile, porous surface will intercept the pollutantsmore easily and facilitate the adsorption process. *e BETsurface area of this adsorbent was 12.89 m2·g−1 whichfavors its adsorption, and the average pore size is15.96 nm.

*e FTIR spectrum of ceramsite adsorbent is given inFigure 4. *e broad band at 3398 cm−1 and a weak peak at1633 cm−1 of ceramsite adsorbent are due to the stretchingvibrations of surface -OH or water [22]. Further, the peaks at1011 cm−1 and 1077 cm−1 are related to the Fe-OH and Si-O,respectively, which are the fundamental groups for theadsorption of phosphorus in this study [23, 24]. *e band at578.7 cm−1 pertains to symmetric stretching vibrations ofFe-O in crystalline lattice of Fe3O4 [25].

3.2. Static Adsorption Studies

3.2.1. Adsorption Isotherms. *e adsorption isotherm dataare given in Table 3. *e maximum phosphorus adsorptioncapacity of ceramsite is achieved using different initialphosphorus concentrations at different temperatures. *eisotherm data are shown in Figure 5 together with the datafitting by Langmuir isotherm. As from Figure 5(a), theincrease of the environment temperature cannot improvethe adsorption capacity under low phosphorus concentra-tion, whereas a prominent increase was observed under highphosphorus concentration, indicating an endothermic na-ture of the adsorption process. *is nature was not signif-icant under low phosphorus concentration due to sufficient

adsorption. *e highest phosphorus adsorption capacitiesare 9.18, 10.56, and 11.61mg·g−1 achieved at 25, 35, and 45°C.*e Langmuir model and Freundlich isotherm are used to fitthe adsorption data, and the isotherm equations areexpressed as follows [7, 26]:

Ce

qe�

1KLqmax

+1

qmaxCe,

ln qe � lnKF +1nlnCe,

(3)

where Ce (mg·L−1) is the phosphorus concentration atequilibrium, qe is the adsorption capacity. qmax (mg·g−1)represents the theoretical maximum adsorption capacity, KL(L·mg−1) is the equilibrium constant related to adsorptionenergy, KF (mg·g−1) is the Freundlich adsorption capacity,and the n is the Freundlich constant.

As shown in Table 3, the experiment data are fitted wellat every control temperature with the Langmuir isothermmodel with higher correlation coefficients but poorly withFreundlich isotherm, and this means that the adsorption ofthe phosphorus onto the ceramsite is limited to monolayercoverage [27]. *e theoretical maximum adsorption ca-pacities calculated from the Langmuir model are 9.84, 11.52,and 13.05mg·g−1, respectively, at 25, 35, and 45°C, which isat the medium level of the previously reported researchstudies listed in Table 4; however, the adsorption time in thisstudy is only 10 minutes which is less than most of the otherresearch studies. We thought the time as a vital operatingparameter in adsorption because the long adsorption du-ration is impossible in wastewater treatment due to a largecost.

Table 2: Extraction procedure for different speciation of phosphorus.

Step Method Speciation1 1 g spent adsorbent added to 25ml 1M NH4Cl, stirring for 1 h at 120 rpm (25°C) Phys-P2 Residual adsorbent added to 25ml 0.1M NaOH, stirring for 1 h at 120 rpm (25°C) Fe/Al-P3 Residual adsorbent added to 25ml 0.5M HCl, stirring for 1 h at 120 rpm (25°C) Ca/Mg-P4 Subtracting above 3 speciation phosphorus from equilibrium phosphorus amount Loss-P

12000

8000

4000

0

Relat

ive i

nten

sity

(a.u

.)

0 20 40 60 802-theta (degrees)

Pristine adsorbentSpent adsorbent

Figure 2: XRD spectra of adsorbent before and after adsorption.

4 Journal of Chemistry

*e essential feature of the Langmuir isotherm can bepresented in terms of the constant, RL, which is expressed asfollows [28]:

RL �1

1 + KLC0. (4)

*e value of RL represents whether the phosphorusadsorption is favorable or unfavorable. If 0

the pseudo-first-order and pseudo-second-order model areused to fit the adsorption data, and the equations are asfollows [37, 38]:

ln qe − qt( � ln qe − K1t,

t

qt�

1K2q

2e

+t

qe,

(5)

where qe and qt are the amount of phosphorus adsorbed perunit mass adsorbent at equilibrium and at different time t,respectively. K1 (min−1) and K2 (g·mg−1·min−1) are the ki-netic rate constants.

All the experimental data fit the pseudo-second-ordermodel well with higher correlation coefficients as shown inTable 6. It is also notable that the experimental qe agrees withthe calculated qe derived from the pseudo-second-ordermodel, and this also demonstrates that the phosphorusadsorption onto ceramsite followed the pseudo-second-order model which means that the adsorption might be therate-limiting step [39].

3.2.3. Effect of Operational Conditions. *e adsorption ofphosphorus onto ceramsite was highly affected by the initialpH condition because it changed the surface charge on the

12

8

4

0

q e (m

g·L–

1 )

0 4 8 12Ce (mg·L–1)

25°C35°C45°C

(a)

0 4 8 12Ce (mg·L–1)

1.2

0.8

0.4

0.0

C e/q

e (g·

L–1 )

25°C35°C45°C

(b)

Figure 5: (a) Adsorption of phosphorus onto ceramsite; (b) Langmuir model fitting (pH� 7, t� 10min, adsorbent dosage� 1 g·L−1, and120 rpm).

Table 4: Removal capacity comparison of different phosphorus adsorbents.

AdsorbentExperimental conditions

qe (mg·g-1) ReferenceAdsorbent dosage (g·L−1) Time (hours) pHMg-loaded biochar 1 4 7 31.15 [30]Modified bauxite residue 40 24 NA 0.35–2.73 [31]Fe-loaded ceramic adsorbent 1 3 7 18.48 [32]Acid-engineered pumice 2 0.5 5–7 9.74 [33]Granular mesoporous ceramic 10 24 4.0–12.0 5.96 [34]Lithium silica fume 2 6 7 24.10 [35]Wasted low-grade iron ore 10 1 5.6 11.44 [36]Industrial waste ceramsite 1 0.167 7 9.84 *is study

Table 5: *e RL values at different initial phosphorus concentrations.

Temperature (°C)RL values at different initial phosphorus concentrations

1mg·L−1 2mg·L−1 5mg·L−1 10mg·L−1 15mg·L−1 20mg·L−1

25 0.43 0.27 0.13 6.90×10−2 4.71× 10−2 3.57×10−2

35 0.42 0.27 0.13 6.79×10−2 4.63×10−2 3.51× 10−2

45 0.46 0.30 0.15 7.83×10−2 5.36×10−2 4.08×10−2

6 Journal of Chemistry

adsorbents, and the pH condition can be considered as oneof the most influential factors in adsorption behavior [40].To investigate the pH dependence of phosphorus adsorptioncapacity, adsorption was conducted under different pH

conditions varying from 1 to 13 with an initial concentrationof 10mg L−1 and adsorbent dosage of 1 g·L−1. As shown inFigure 7, the adsorption capacity was on the rise followingthe initial pH from 1 to 5, achieving the highest adsorption

10

8

6

4

2

0

0 200 400 600

Phos

phor

us co

ncen

trar

tion

(mg·

L–1 )

t (s)

10mg·L–1

5mg·L–1

2mg·L–1

(a)

2

1

0

–1

–2

–30 100 200 300 400 500

In (q

e–q t

)

t (s)

10mg·L–1

5mg·L–1

2mg·L–1

(b)

250

200

150

100

50

0

0 200 400 600t (s)

t/qt (

s·g/m

g)

10 mg L–1

5 mg L–1

2 mg L–1

(c)

Figure 6: (a) Adsorption kinetics of phosphorus onto ceramsite; (b) pseudo-first-order model fitting; (c) pseudo-second-order model fitting(pH� 7, t� 10min, adsorbent dosage� 0.5 g·L−1, 120 rpm, and 25°C).

Table 6: Pseudo-first-order and pseudo-second-order kinetics constants.

Phosphorus concentration(mg·L−1)

Experimental value qe(mg·g−1)

Pseudo-first-order model Pseudo-second-order model

K1 (min−1)qe

(mg·g−1) R2 K2

(g·mg−1·min−1)qe

(mg·g−1) R2

2 2.72 7.20×10−3 2.03 0.9901 5.96×10−3 2.94 0.99315 5.63 4.51× 10−3 3.10 0.9526 4.10×10−3 5.70 0.991810 14.89 6.85×10−3 5.73 0.9687 3.37×10−3 15.17 0.9991

Journal of Chemistry 7

capacity at pH� 5, and after that, a negative influence of pHwas observed. *e same tendency was also observed in otherresearch studies but with higher adsorption capacity in lowpH conditions [12]. *is result may be because the pH has agreat influence on the phosphorus species and ceramsitesurface charge. As it is well known the phosphorus specieswere greatly influenced by pH, under 25°C condition, thepredominated phosphorus species were H2PO4−, HPO42−,and PO43− with the pH starting from 2.1, 7.2, and 12.3,respectively, resulting in more negatively charged phos-phorus species with the increase of pH [12].*e point of zerocharge of pH is plotted in Figure 8 which was in the pH rangefrom 7 to 8, with lower pH than pHpzc, the surface of theadsorbent was positively charged, and on the contrary, thesurface was negatively charged with higher pH than pHpzc.Hence, when the surrounding pH was lower than pHpzc,with the decrease of pH, the amount of the positivelycharged sites on the ceramsite increased. However, theadsorption behavior under low pH was compromised whichmay be owing to the less negative form of phosphorus(H3PO4 and H2PO4−), while with the increase of pH, theincreased percentage of HPO42− built a strong bond with theFe/Al surface resulting in better adsorption performance.Besides, the extremely low pH surrounding may disassemblethe fraction of ceramsite which will release more anions intothe solution competing with phosphorus. While underhighly alkaline condition, the surface charge was highlynegative which should have an adverse impact on phos-phorus removal; however, the alkaline condition promotedthe transformation of HPO42− to PO43− which is more activeto form strong precipitation with iron and aluminumcausing stable adsorption behavior under high alkalinecondition. *e pH-dependent adsorption curve indicatedthat the adsorption was inhibited under low pH (1–3) andstayed active afterward even at pH� 13.*e solution pH wasalso measured after reaching equilibrium, presented as blue

quadrates in Figure 7, and it was seen that the equilibriumpH increased slightly with initial pH ranging from 1 to 9 anddecreased at highly alkaline conditions, which also can beused to demonstrate that negatively charged particles werereleased under the acid condition and compete withphosphorus anions.

For the investigation of the effect of dosage on phos-phorus adsorption, the adsorption experiments were con-ducted with different dosage amounts ranging from 0.5 to10 g·L−1 in the presence of 50mg·L−1 initial phosphorus at120 rpm for 10min (Figure 9). *e phosphorus adsorptionrate significantly increased from 15.905% to 99.24% withincreasing ceramsite dosage amount from 0.5 to 5 g·L−1. *eadsorption rate stayed constant after 5 g·L−1 adsorbent withthe effluent phosphorus concentration below 1.5mg·L−1.With the increase of the dosage amount, the active sitesincreased which can adsorb more phosphorus, leading to aninevitable increasing adsorption rate, and on the other hand,the phosphorus adsorption capacity in unit mass decreasedfrom 15.905 to 0.995mg g−1 because, with the increase ofadsorbents, the adsorption force of specific surface area gotweakened [41]. It was seen from that, considering largeinitial phosphorus concentration, 5 g·L−1 adsorbent wasfound to be an effective dosage.

Figure 10 presents the influence of the coexisting anionson the phosphorus adsorption including Cl−, F−, SiO32−, andSO42− anions at different concentrations (20 and100mg·L−1). *e blue line in this figure represents the ad-sorption capacity without coexisting anions under the sameexperimental conditions, and as from the comparison, theinfluence of the anions in descending order was as follows:SO42−, SiO32−, F−, and Cl−. All four anions present in thesolutions affected the phosphorus adsorption of ceramsite,but still, no remarkable impact was detected. From Fig-ure 10, with 20mg·L−1 of coexisting anions, the phosphateremoval rate achieved 99.31%, 99.12%, 98.89%, and 98.69%for Cl−, F−, SiO32−, and SO42−, respectively. Under higherconcentration of coexisting anions (100mg·L−1), no signif-icant decrease was detected. Sulfate, because iionic radii(2.3 Å) is similar to that of phosphate (2.38 Å) which willcause competitive adsorption, was the most influential anion

12

8

4

0

q e (m

g g–

1 )

0 4 8 12Initial pH

12

8

4

0

Equi

libriu

m p

H

Adsorption capacityEquilibrium pH

Figure 7: Effect of pHon the phosphorus adsorption behavior andfinalpH after reaching equilibrium (t� 10min, adsorbent dosage� 1g·L−1,120 rpm, initial phosphorus concentration� 10mg·L−1, and 25°C).

1

0

–1

–2

∆pH

2 4 6 8 10Initial pH

Figure 8: Point of zero charge of ceramsite.

8 Journal of Chemistry

[42]. However, the detrimental effect caused by this com-petitive anion is negligible.*is suggested that the adsorbentshowed an exceptional anti-interference ability to othercoexisting anions, proving the applicability of the adsorbentin complicated real water treatment.

3.2.4. Speciation Analysis of Adsorbed Phosphorus. To figureout the phosphorus adsorption mechanism of ceramsite, thespeciation of the adsorbed phosphorus was distinguishedusing the sequential extraction procedure. From Figure 11,the Fe/Al-P was the dominating adsorption speciation, ac-counting for 85.91% of all the phosphorus adsorbed. *isdemonstrated that the adsorption of phosphorus wasdominated by iron and aluminum which were the major

components of the red mud (36.00% and 22.40%, respec-tively, Table 1), and the phosphorus was precipitated on thesurface of the ceramsite with iron and aluminum. In ad-dition, 2.74% and 9.42% of phosphorus were adsorbed byphysical adsorption and Ca/Mg adsorption, and the lowpercentage of Ca/Mg adsorption was due to the less activecalcium in the ceramsite. Furthermore, only 1.93% of thetotal adsorbed phosphorus was not detected (loss-P); itindicated that all phosphorus was adsorbed at the surface ofthe ceramsite, and little phosphorus was removed with thedissolved iron or aluminum. Because of that, the phosphoruswill remain on the surface of the ceramsite and can bedesorbed using desorbing agents for the recovery ofphosphorus.

3.2.5. Desorption of Phosphorus. Phosphorus desorptionfrom the ceramsite is to help regenerate the adsorbents, andthen the regenerated adsorbents can be used to adsorbphosphorus again. Preliminary research studies have indi-cated that sodium hydroxide, sodium bicarbonate, andsodium chloride can be used to regenerate the adsorbents[40, 43]. In this study, the desorption studies were conductedwith different desorbing agents such as 0.1M NaCl, 0.1MNa2CO3, 0.1M NaOH, 0.1M HCl, and 0.1M H2SO4, andphosphorus released from the adsorbents was measured toensure the most functional desorbing agent. Unlike thepreliminary research studies, the sodium hydroxide andsodium chloride barely desorbed the phosphorus from thesurface, especially for sodium hydroxide, with less than 10%desorbing percentage. *is might be caused by the reasonthat the majority of the phosphorus was adsorbed by ironand aluminum, and adding OH− will make the precipitationless soluble and difficult to break down. As from Figure 12,the best performance was achieved for 0.1M HCl and 0.1MNa2CO3 with 82.48% and 75.46% desorbing phosphorus oftotal phosphorus adsorbed, respectively. 0.1M H2SO4 was

96

98

100

SO42–SiO32–F–

Ads

orpt

ion

perc

enta

ge (%

)

20 mg L–1

100 mg L–1

Cl–

Adsorption without coexisting anions

Figure 10: *e effect of coexisting anions on phosphorus ad-sorption (pH� 7, t� 10min, adsorbent dosage� 2 g·L−1, 120 rpm,initial phosphorus concentration� 10mg·L−1, and 25°C).

100

80

6020

0

Perc

enta

ge (%

)

Phys-P Fe/Al-P Ca/Mg-P Loss-PSpeciation of adsorbed phosphorus

Figure 11: Speciation analysis of adsorbed phosphorus onceramsite (pH� 7, t� 10min, adsorbent dosage� 2 g·L−1, 120 rpm,initial phosphorus concentration� 10mg·L−1, and 25°C).

100

80

60

40

20

0

Adso

rptio

n pe

rcen

tage

(%)

0 5 10Adsorbent dosage (g L–1)

16

12

8

4

q e (m

g g–

1 )

Adsorption percentageAdsorption capacity

Figure 9: *e effect of dosage on phosphorus adsorption (pH� 7,t� 10min, 120 rpm, initial phosphorus concentration� 50mg·L−1,and 25°C)

Journal of Chemistry 9

also found to be very effective in the desorbing procedure.However, when testing the concentration of iron and alu-minum in the solutions after desorption, higher concen-tration was observed with 0.1M HCl and 0.1M H2SO4,indicating the adsorbent was dissolved under the acidicsolutions which caused desorption of phosphorus. *e ironand aluminum concentrations after desorption were 0.53and 1.23mg L−1 for 0.1M HCl and 0.50 and 0.96mg·L−1 for0.1M H2SO4, respectively. Furthermore, nearly no iron/aluminum was detected after desorption using sodiumcarbonate. Consequently, sodium carbonate was chosen asthe desorption agent for future use.

3.2.6. Phosphorus Adsorption of Real Water Samples. Totruly investigate the feasibility of application for phosphorusremoval using the ceramsite, the real water samples fromdifferent sources were collected and the detail of the samplesis listed in Table 7.*e water samples were collected from (a)water treatment plant, (b) wastewater treatment plant, (c)park, (d) river, and (e) runoff. *e collected water samplesinitially contained phosphorus concentrations ranged from0.04 to 3.23mg·L−1, and the COD ranged from 14 to 142.*eresults of phosphorus concentration before and after ad-sorption are shown in Figure 13. *e phosphorus concen-trations after adsorption decreased under 0.5mg·L−1 exceptfor sample 6 which possessed more complicated waterquality; however, it still adsorbed almost half of the phos-phorus present in the water. *is suggested that the ap-plication of ceramsite for real water treatment was feasiblefor low-contaminated aqueous solutions and also promisingfor complicated water samples if the appropriate adsorbentdosage was applied.

3.3. Dynamic Column Adsorption. Due to practical pur-poses, the column adsorption experiment was conducted inthis research. Figure 14 shows the effect of inlet phosphorusconcentrations on the effluent phosphorus concentration (C

is the effluent phosphorus concentration and C0 is the initialphosphorus concentration). *e results show that afterapproximately 30 and 40 minutes, with initial adsorbateconcentration at 2 and 5mg·L−1, the phosphorus concen-tration in the effluent rises dramatically, indicating theadsorbent column has been broken through. Also, higheradsorbate concentration promotes the saturation time. After50 minutes, the effluent phosphorus concentration is close tothe influent phosphorus concentration (2mg·L−1) whichindicates the adsorbent column is completely exhausted bythe phosphorus. With initial phosphorus concentration at2mg·L−1, the water samples collected prior to 34 minutesmeet the threshold of the Chinese discharge standard ofpollutants for municipal wastewater treatment plant(GB18918-2002), with the phosphorus concentration lowerthan 0.3mg·L−1.*at is, the ceramsite adsorbent can remove85% phosphorus using a fixed-bed column in a realapplication.

3.4. Water Quality after Adsorption. *e water quality afteradsorption was tested by ICP-MS, to ensure the safety of theceramsite use in water treatment. Unlike other research

100

80

60

40

20

0

Perc

enta

ge (%

)

Different desorbing agents

0.1

M N

aCl

0.1

M N

a 2CO

3

0.1

M N

aOH

0.1

M H

Cl

0.1

M H

2SO

4Figure 12: Percentage of phosphorus released from ceramsiteusing different desorbing agents (equilibrium: pH� 7, t� 10min,adsorbent dosage� 1 g·L−1, 120 rpm, initial phosphorusconcentration� 10mg·L−1, and 25°C).

Table 7: Details of collected water samples.

SampleID pH

Temperature(°C)

COD(mg·L−1)

NH4+-N(mg·L−1) PO4

3−(mg·L−1)

1 7.64 17.2 24 11.73 2.902 7.44 16.9 21 0 2.903 7.57 14.3 19 6.74 2.524 8.07 22.2 38 0.16 0.245 6.61 12.8 13 0.04 0.046 7.59 12.4 142 13.11 3.237 7.51 21.5 31 16.43 1.398 6.98 20.2 26 8.02 1.12

3

2

1

0

100

80

60

40

20

0

Phos

phor

us co

ncen

trat

ion

(mg

L–1 )

Phos

phor

us ad

sorp

tion

rate

(%)

1 2 3 4 5 6 7 8Collected water samples

Before adsorption

A�er adsorption

Adsorption rate

Figure 13: Phosphorus adsorption behavior of collected watersamples (equilibrium: t� 10min, adsorbent dosage� 2 g·L−1,120 rpm, and 25°C).

10 Journal of Chemistry

studies, the objective of this work is to (1) treat the hazardousmaterials, (2) reuse them, and (3) ensure the feasibility foractual use but not for lab researches. Many research studieshave investigated adsorbents with large adsorption capacityposing promising future; however, few of them studied thewater quality after adsorption which is of great significancebecause the fundamental purpose of the adsorption treat-ment is to treat the water but not introduce more hazardousions into the water. In addition, some of themmay study theleaching toxicity, but the threshold standard they use is forthe identification of hazardous materials but not forwastewater treatment standards. In this research, the watersamples after 10min, 20min, and 40min dynamic ad-sorption were tested to determine the metal concentrations,compared with the Chinese discharge standard of pollutantsfor municipal wastewater treatment plant (GB 18918–2002).

*e concentrations of different metals after adsorptionand the metal leaching concentrations of raw materials areshown in Table 8. In general, the concentrations aftersintering decreased significantly compared with the

leaching concentrations of raw materials, suggesting thatthe fabrication helped stabilize the metals inside the rawmaterials. Additionally, among the metals tested in thisstudy, there are five metal pollutants listed as class I pol-lutants: As, Hg, Pb, Cd, and Cr. *e measurement resultsshowed that the As, Hg, Pb, and Cr concentrations of allwater samples after adsorption column met completely thedischarge standard of China. *e Cd concentration after 40minutes, however, exceeded 0.01mg·L−1 which will needfurther treatment. *is may be caused by the large presenceof cadmium inside the red mud (3.68mg·L−1 using TCLPtest), and future fabrication should focus on the furtherstabilization of the cadmium. In the wastewater dischargestandard, there are no specific limits for Fe, Mg, Al, and Caelements; however, in this study, the concentrations werelowered to an unharmful level. Meanwhile, the remainingelements were within the discharge standard of pollutantsfor the wastewater treatment plant. *erefore, the adsor-bent made in this research is relatively safe to use inwastewater treatment.

1.0

0.8

0.6

0.4

0.2

0.0

C/C 0

0 20 40 60Time (min)

2 ppm5 ppm

Figure 14: Removal of phosphorus by fixed-bed column (HRT�10min and dosage� 20 g).

Table 8: Trace metal element concentrations in the effluent (compared with leaching concentrations from raw materials).

Metals (mg L−1)Water samples after column Toxicity leaching tests

Maximum contaminant level10min 20min 40min Red mud Fly ash Riverbed sediment

As 0.03 0.03 0.05 0.36 0.07 0.15 0.10Hg ND ND ND 0.01 0 ND 0.01Pb ND ND ND 0.01 0 ND 0.10Cd 0.01 0.01 0.02 3.68 0.01 0.11 0.01Cr 0.06 0.02 0.04 1.33 0.26 ND 0.10Fe ND ND 0.09 0.96 0.29 0 NMMg 0.46 1.15 1.60 9.31 8.53 30.07 NMAl 0.51 1.05 1.04 2.11 28.86 0.01 NMCa 3.87 18.31 8.12 382.97 427.73 605.03 NMCu 0.01 0.01 0.01 0.05 0.04 0.02 0.50Mn ND ND 0.007 0.01 0.09 5.85 2.00Zn 0.01 0.01 0.03 0.07 0.11 0.46 1.00ND: not detected; NM: not mentioned.

Journal of Chemistry 11

4. Conclusion

For the first time, the riverbed sediments, red mud, and flyash were used as the main materials for ceramsite ad-sorbent fabrication. *e adsorption capacity for phos-phorus was investigated along with the mechanism studyand preliminary application explore. Due to the iron andaluminum present in the raw materials, the adsorptioncapacity of ceramsite is up to 9.84mg g−1. *e phosphorusadsorption onto ceramsite follows the Langmuir mono-layer adsorption model and pseudo-second-order kineticmodel. *e adsorbent exhibited a great anti-interferenceability to other anions simultaneously existing in thesolutions; besides, the results of phosphorus adsorptionfrom collected real water samples further suggest that theceramsite adsorbent in this research can be effectiveacross a wide range of conditions and suitable for dif-ferent water environments. Moreover, it only takes 10minutes for the adsorbent to reach equilibrium in thesolutions which are far more rapid than most of theresearch studies; this greatly lowers the cost of the ad-sorption treatment if applying in treatment plant.Leaching toxicity of the ceramsite is below the wastewaterdischarge standard. In a word, this ceramsite preparedwith industrial wastes is a low-cost, rapid, safe, and ef-fective adsorbent to remove phosphorus from real water.To a certain content, the research has realized the purpose“use the waste to treat the waste”. Further research shouldfocus on improving the phosphorus adsorption capacityto remove more phosphorus by optimizing the preparingconditions. In addition, to avoid second pollution, theleachability of the ceramsite adsorbents needs to becontrolled which will greatly promote the applicability ofthe adsorbents.

Data Availability

*e data used to support the findings of this study areavailable from the corresponding author upon request.

Additional Points

A novel ceramsite adsorbent was prepared with contami-nated sediment. Adsorbent showed rapid adsorption be-havior and great adsorption capacity. *e adsorbent can beused for real applications with no environmental influence.

Conflicts of Interest

*e authors declare that there are no conflicts of interestregarding the publication of this paper.

Acknowledgments

*is study was funded by the Major Science and TechnologyInnovation Project of Shandong Province (Grant no.2018YFJH0902).

References

[1] O. Axinte, I. S. Bădescu, C. Stroe, V. Neacsu, L. Bulgariu, andD. Bulgariu, “Evolution of trophic parameters from Amaralake,” Environmental Engineering and Management Journal,vol. 14, no. 3, pp. 559–565, 2015.

[2] O. Eljamal, A. M. E. Khalil, Y. Sugihara, and N. Matsunaga,“Phosphorus removal from aqueous solution by nanoscalezero valent iron in the presence of copper chloride,” ChemicalEngineering Journal, vol. 293, pp. 225–231, 2016.

[3] Z. Yang, L. Liu, L. Zhao et al., “Preparation and evaluation ofbis (diallyl alkyl tertiary ammonium salt) polymer as apromising adsorbent for phosphorus removal,” Journal ofEnvironmental Sciences, vol. 86, pp. 24–37, 2019.

[4] D. Cordell, J.-O. Drangert, and S. White, “*e story ofphosphorus: global food security and food for thought,”Global Environmental Change, vol. 19, no. 2, pp. 292–305,2009.

[5] S. Nazerdeylami and R. Zare-Dorabei, “Simultaneous ad-sorption of Hg2+, Cd2+ and Cu2+ ions from aqueous so-lution with mesoporous silica/DZ and conditions optimisewith experimental design: kinetic and isothermal studies,”Micro & Nano Letters, vol. 14, no. 8, pp. 823–827, 2019.

[6] F. Ramezani and R. Zare-Dorabei, “Simultaneous ultrasonic-assisted removal of malachite green and methylene blue fromaqueous solution by Zr-SBA-15,” Polyhedron, vol. 166,pp. 153–161, 2019.

[7] R. Zare-Dorabei, S. M. Ferdowsi, A. Barzin, and A. Tadjarodi,“Highly efficient simultaneous ultrasonic-assisted adsorptionof Pb(II), Cd(II), Ni(II) and Cu (II) ions from aqueous so-lutions by graphene oxide modified with 2,2′-dipyridylamine:central composite design optimization,” Ultrasonics Sono-chemistry, vol. 32, pp. 265–276, 2016.

[8] P. G. Tratnyek and R. L. Johnson, “Nanotechnologies forenvironmental cleanup,” Nano Today, vol. 1, no. 2, pp. 44–48,2006.

[9] W. Qiao, H. Bai, T. Tang, J. Miao, and Q. Yang, “Recovery andutilization of phosphorus in wastewater by magnetic Fe3O4/Zn-Al-Fe-La layered double hydroxides(LDHs),” Colloids andSurfaces A: Physicochemical and Engineering Aspects, vol. 577,pp. 118–128, 2019.

[10] X. Li, A. H. Elgarhy, M. E. Hassan, Y. Chen, G. Liu, andR. ElKorashey, “Removal of inorganic and organic phos-phorus compounds from aqueous solution by ferrihydritedecoration onto graphene,” Environmental Monitoring andAssessment, vol. 192, no. 6, 2020.

[11] J. Liu, Q. Zhou, J. Chen, L. Zhang, and N. Chang, “Phosphateadsorption on hydroxyl-iron-lanthanum doped activatedcarbon fiber,” Chemical Engineering Journal, vol. 215-216,pp. 859–867, 2013.

[12] Y. Wang, Y. Yu, H. Li, and C. Shen, “Comparison study ofphosphorus adsorption on different waste solids: fly ash, redmud and ferric-alum water treatment residues,” Journal ofEnvironmental Sciences, vol. 50, pp. 79–86, 2016.

[13] S. Wang, H. M. Ang, M. O. Tadé, and R. Mud, “Novel ap-plications of red mud as coagulant, adsorbent and catalyst forenvironmentally benign processes,” Chemosphere, vol. 72,no. 11, pp. 1621–1635, 2008.

[14] L. Zeng, X. Li, and J. Liu, “Adsorptive removal of phosphatefrom aqueous solutions using iron oxide tailings,” WaterResearch, vol. 38, no. 5, pp. 1318–1326, 2004.

[15] S. Yasipourtehrani and T. Evans, “Pyrometallurgical processfor recycling of valuable materials and waste management:

12 Journal of Chemistry

valorisation applications of blast furnace slags,” Sustainableand Economic Waste Management, vol. 9, pp. 1–12, 2019.

[16] V. M. Tangde, S. S. Prajapati, B. B. Mandal, andN. P. Kulkarni, “Study of kinetics and thermodynamics ofremoval of phosphate from aqueous solution using activatedred mud,” International Journal of Environmental Research,vol. 11, no. 1, pp. 39–47, 2017.

[17] J. L. Zou, G. R. Xu, and G. B. Li, “Ceramsite obtained fromwater and wastewater sludge and its characteristics affected byFe2O3, CaO, and MgO,” Journal of Hazardous Materials,vol. 165, no. 1–3, pp. 995–1001, 2009.

[18] P. LIU, H.-j. ZHAO, L.-l. WANG et al., “Analysis of heavymetal sources for vegetable soils from Shandong province,China,” Agricultural Sciences in China, vol. 10, no. 1,pp. 109–119, 2011.

[19] A. E. Zidan, N. M. Hilal, A. A. Emam, and A. A. El-Bayaa,“Adsorption of barium and iron ions from aqueous solutionsby the activated carbon produced from masot ash,” LifeScience Journal, vol. 10, no. 3, pp. 2011–2020, 2013.

[20] Z. Zhu, L. Li, H. Zhang, Y. Qiu, and J. Zhao, “Adsorption ofLead and cadmium on ca-deficient hydroxyapatite,” Sepa-ration Science and Technology, vol. 45, no. 2, pp. 262–268,2010.

[21] G. Cheng, Q. Li, Z. Su, S. Sheng, and J. Fu, “Preparation,optimization, and application of sustainable ceramsite sub-strate from coal fly ash/waterworks sludge/oyster shell forphosphorus immobilization in constructed wetlands,” Journalof Cleaner Production, vol. 175, pp. 572–581, 2018.

[22] M. K. Sahu, S. Mandal, S. S. Dash, P. Badhai, and R. K. Patel,“Removal of Pb(II) from aqueous solution by acid activatedred mud,” Journal of Environmental Chemical Engineering,vol. 1, no. 4, pp. 1315–1324, 2013.

[23] Z. Cheng, F. Fu, D. D. Dionysiou, and B. Tang, “Adsorption,oxidation, and reduction behavior of arsenic in the removal ofaqueous As(III) by mesoporous Fe/Al bimetallic particles,”Water Research, vol. 96, pp. 22–31, 2016.

[24] A. Naga Babu, G. V. Krishna Mohan, K. Kalpana, andK. Ravindhranath, “Removal of fluoride from water usingH2O2-treated fine red mud doped in Zn-alginate beads asadsorbent,” Journal of Environmental Chemical Engineering,vol. 6, no. 1, pp. 906–916, 2018.

[25] I. Akin, G. Arslan, A. Tor, M. Ersoz, and Y. Cengeloglu,“Arsenic(V) removal from underground water by magneticnanoparticles synthesized from waste red mud,” Journal ofHazardous Materials, vol. 235-236, pp. 62–68, 2012.

[26] Y. Zhou, L. Luan, B. Tang et al., “Fabrication of Schiff basedecorated PAMAM dendrimer/magnetic Fe3O4 for selectiveremoval of aqueous Hg(II),” Chemical Engineering Journal,vol. 398, Article ID 125651, 2020.

[27] J. Febrianto, A. N. Kosasih, J. Sunarso, Y.-H. Ju, N. Indraswati,and S. Ismadji, “Equilibrium and kinetic studies in adsorptionof heavy metals using biosorbent: a summary of recentstudies,” Journal of Hazardous Materials, vol. 162, no. 2-3,pp. 616–645, 2009.

[28] S. Meenakshi, C. S. Sundaram, and R. Sukumar, “Enhancedfluoride sorption by mechanochemically activated kaolinites,”Journal of Hazardous Materials, vol. 153, no. 1-2, pp. 164–172,2008.

[29] J. Niu, P. Ding, X. Jia, G. Hu, and Z. Li, “Study of theproperties and mechanism of deep reduction and efficientadsorption of Cr(VI) by low-cost Fe3O4-modified ceramsite,”Science of;e Total Environment, vol. 688, pp. 994–1004, 2019.

[30] Y.-H. Jiang, A.-Y. Li, H. Deng et al., “Characteristics of ni-trogen and phosphorus adsorption by Mg-loaded biochar

from different feedstocks,” Bioresource Technology, vol. 276,pp. 183–189, 2019.

[31] P. B. Cusack, M. G. Healy, P. C. Ryan et al., “Enhancement ofbauxite residue as a low-cost adsorbent for phosphorus inaqueous solution, using seawater and gypsum treatments,”Journal of Cleaner Production, vol. 179, pp. 217–224, 2018.

[32] D. Wang, N. Chen, Y. Yu, W. Hu, and C. Feng, “Investigationon the adsorption of phosphorus by Fe-loaded ceramic ad-sorbent,” Journal of Colloid and Interface Science, vol. 464,pp. 277–284, 2016.

[33] G. H. Safari, M. Zarrabi, M. Hoseini, H. Kamani, J. Jaafari, andA. H. Mahvi, “Trends of natural and acid-engineered pumiceonto phosphorus ions in aquatic environment: adsorbentpreparation, characterization, and kinetic and equilibriummodeling,” Desalination andWater Treatment, vol. 54, no. 11,pp. 3031–3043, 2015.

[34] D. Wang, W. Hu, N. Chen, Y. Yu, C. Tian, and C. Feng,“Removal of phosphorus from aqueous solutions by granularmesoporous ceramic adsorbent based on Hangjin clay,”Desalination and Water Treatment, vol. 57, no. 47,pp. 22400–22412, 2016.

[35] R. Xie, Y. Chen, T. Cheng, Y. Lai, W. Jiang, and Z. Yang,“Study on an effective industrial waste-based adsorbent for theadsorptive removal of phosphorus from wastewater: equi-librium and kinetics studies,” Water Science and Technology,vol. 73, no. 8, pp. 1891–1900, 2016.

[36] X. Yuan, C. Bai, W. Xia, B. Xie, and J. An, “Phosphate ad-sorption characteristics of wasted low-grade iron ore withphosphorus used as natural adsorbent for aqueous solution,”Desalination and Water Treatment, vol. 54, no. 11,pp. 3020–3030, 2015.

[37] Z. Zhang, Y. Niu, H. Chen et al., “Feasible one-pot sequentialsynthesis of aminopyridine functionalized magnetic Fe3O4hybrids for robust capture of aqueous Hg(II) and Ag(I),” ACSSustainable Chemistry & Engineering, vol. 7, no. 7,pp. 7324–7337, 2019.

[38] X. Song, Y. Niu, Z. Qiu et al., “Adsorption of Hg(II) and Ag(I)from fuel ethanol by silica gel supported sulfur-containingPAMAM dendrimers: kinetics, equilibrium and thermody-namics,” Fuel, vol. 206, pp. 80–88, 2017.

[39] M. Hanif, R. Nadeem, M. Zafar, K. Akhtar, and H. Bhatti,“Kinetic studies for Ni(II) biosorption from industrialwastewater by Cassia fistula (Golden Shower) biomass,”Journal of Hazardous Materials, vol. 145, no. 3, pp. 501–505,2007.

[40] S. Li, T. Lei, F. Jiang et al., “Tuning the morphology andadsorption capacity of Al-MIL-101 analogues with Fe3+ forphosphorus removal from water,” Journal of Colloid andInterface Science, vol. 560, pp. 321–329, 2020.

[41] Q.-x. Jing, Y.-y. Wang, L.-y. Chai et al., “Adsorption of copperions on porous ceramsite prepared by diatomite and tungstenresidue,” Transactions of Nonferrous Metals Society of China,vol. 28, no. 5, pp. 1053–1060, 2018.

[42] J. Jang and D. S. Lee, “Effective phosphorus removal usingchitosan/Ca-organically modified montmorillonite beads inbatch and fixed-bed column studies,” Journal of HazardousMaterials, vol. 375, pp. 9–18, 2019.

[43] K. Y. Koh, S. Zhang, and J. Paul Chen, “Hydrothermallysynthesized lanthanum carbonate nanorod for adsorption ofphosphorus: material synthesis and optimization, and dem-onstration of excellent performance,” Chemical EngineeringJournal, vol. 380, p. 122153, 2020.

Journal of Chemistry 13