porous spherical cellulose carrier modified with polyethyleneimine and its adsorption for cr(iii)...

Chinese Journal of Chemical Engineering xxx (2014) xxx–xxx

CJCHE-00051; No of Pages 7

Contents lists available at ScienceDirect

Chinese Journal of Chemical Engineering

j ourna l homepage: www.e lsev ie r .com/ locate /CJCHE

Separation Science and Engineering

Porous Spherical Cellulose Carrier Modified with Polyethyleneimine and Its Adsorptionfor Cr(III) and Fe(III) from Aqueous Solutions☆

Zhijian He 1,2, Hang Song 2, Yannan Cui 2, Weixia Zhu 2, Kaifeng Du 2, Shun Yao 2,⁎1 School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang 621000, China2 Department of Pharmaceutical and Biological Engineering, Sichuan University, Chengdu 610065, China

☆ Supported by the National Natural Science Foun81102344), the Project of Education Department in Sichuof Science and Technology of Mianyang City of China (10Y⁎ Corresponding author.

E-mail address: [email protected] (S. Yao).

http://dx.doi.org/10.1016/j.cjche.2014.07.0011004-9541/© 2014 The Chemical Industry and Engineerin

Please cite this article as: Z. He, et al., H. Songand Fe(III) From Aqueous Solutions, Chin. J. C

a b s t r a c t
a r t i c l e i n f o
Article history:Received 26 April 2014Received in revised form 12 June 2014Accepted 14 July 2014Available online xxxx

Keywords:PolyethyleneimineCellulose particleAdsorptionCr(III)Fe(III)

An efficient porous spherical polyethyleneimine-cellulose (PEI-cell) absorbent was synthesized and char-acterized. The main influencing factors and adsorption mechanism for two typical metal ions, Cr3+ andFe3+, were investigated. The adsorption performance primarily depends on the initial concentration ofmetal ions, pH value and temperature, and the chelation action between N atoms of PEI-cell and metalions plays an important role. Under dynamic adsorption conditions, the saturation adsorption ofpolyethyleneimine-cellulose is 83.98 mg·g−1 for Cr(III) and 377.19 mg·g−1 for Fe(III), higher than report-ed data and that of unmodified cellulose. The adsorption can be well described with second-order kineticequation and Freundlich adsorption model, and ΔH, ΔG and ΔS of the adsorption are all negative. With 5%HCl as eluent, the elution ratio of Cr(III) and Fe(III) achieved 99.88% and 97.74% at 313 K, respectively.After the porous PEI-cell was reused 6 times, it still presented satisfactory adsorption performance.Above results show the advantages such as easily-acquired raw material, high efficiency, stable recyclingperformance and biodegradability.© 2014The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.

1. Introduction

Many industries, such as pharmacy, battery, rubbers, leather tan-ning, dye, paper, coating, car, aeronautic and steel generate large quan-tities of wastewater containing chromium and iron [1,2]. The twometalions are readily infused in underground water and contaminate drink-ingwater because they are highlywater-soluble and diffusible. Effectiveremoval of heavy metals in wastewater is of great importance. Variousmethods have been developed and employed, such as adsorption, neu-tralization, ion exchange, precipitation and biological purification [3–7].Among these methods, adsorption is one of themost popular and effec-tive techniques, which offers great flexibility in design, operation, andregeneration in many situations. Some adsorbents reported for Cr(III)and Fe(III) include lignin [8], biochar and sugarcane pulp residue [9],bread mold fungus [10], activated carbon [11], sugarcane bagasse mod-ified with sodium hydroxide and citric acid [12], zeolite synthesizedfromfly ash [13], thiourea cross-linked chitosan [14], unmodified raphiapalm fruit endocarp [15], hazelnut hull [16], chitosan–tripolyphosphate

dation of China (81373284,an (14ZB0267) and the Bureau003-8).

g Society of China, and Chemical Ind

, Porous Spherical Cellulose Chem. Eng. (2014), http://dx.d

beads [17], imprinted polymer [18], polyacrylamide grafted activatedcarbon [19], and so on.

As abundant renewable and biodegradable adsorbent materials, cel-lulose and modified cellulose are widely used in wastewater treatment,chemical industry, and medication adsorption [20,21]. Cellulose can in-teractwith adsorbates through hydrogen bond, complexation and otherinteractions. Different porous cellulose adsorbents with high perfor-mance can be prepared by grafting functional polymers on the surface,which are effective to remove heavy metals [22]. The solid adsorptionmaterials can well combine the functionality of polymers and excellentproperties of porous cellulose, such as low cost, high specific area, envi-ronmentally friendly, strong mechanical property, and good chemicaland thermal stability.

Polyethyleneimine (PEI) is a water-soluble polyamine and its aque-ous solution is alkalinewith a lot of aminogroups on itsmacromolecularchains. Commercial PEI is a branched macromolecule and the ratio ofprimary, secondary and ternary amine groups is approximately 1:2:1[23], which is well known for its metal chelation potentiality. In thisstudy, PEI is grafted onto the surface of porous cellulose particles to ob-tain a solid adsorbent PEI-cell, which is used to remove Cr(III) and Fe(III)ions from their aqueous solutions. Compared with some adsorbentsreported [24–26], the raw material is relatively more available andcheap, and the two-step synthesis process is simple. The PEI-cell adsor-bent has an intense adsorption capability for Cr(III) and Fe(III) due tothe strong chelation between nitrogen atoms and metal ions. This is a

ustry Press. All rights reserved.

arrier ModifiedWith Polyethyleneimine and Its Adsorption For Cr(III)oi.org/10.1016/j.cjche.2014.07.001

http://dx.doi.org/10.1016/j.cjche.2014.07.001

mailto:[email protected]


http://www.sciencedirect.com/science/journal/

www.elsevier.com/locate/CJCHE


2 Z. He et al. / Chinese Journal of Chemical Engineering xxx (2014) xxx–xxx

promising method to graft functional polymer on porous cellulose toprepare efficient adsorbents for the removal of heavy metal ions fromindustrial wastewater.

2. Experimental

2.1. Materials

Medical degrease cotton (100% cotton fiber) was provided byHualu Hygienic Material Co. Ltd., Shandong, China. PEI (99% pu-rity) was provided by Hangjia Biological Medicine Co. Ltd.,Sichuan, China. 1,5-Diphenyl carbazide and phenanthroline(purity N 98%) was purchased from Chengdu Kelong ReagentCo. Ltd., Sichuan, China. Other reagents were all of analyticalgrade.

2.2. Two-step synthesis of porous polyethyleneimine-cellulose particle

(1) The cotton was infused with 5 mol·L−1 NaOH aqueous solutionfor 2 h and aged at 25 °C for 2 days. 1.5 mol·L−1 NaOH wasadded to get liquid glue after sulfonation with CS2. The brilliantyellow solution and nano-CaCO3 were stirred efficiently withthe shaker. Then the mixture was transferred to a large roundbottom flask containing transformer oil and stirred persis-tently at 90 °C for 2.5 h. After the mixture was cooled toroom temperature, the porous cellulose particles wererinsed with ultrapure water several times and externalnano-CaCO3 was removed with HCl. The porous celluloseparticles were sieved with size range from 100 to200 mesh. Finally, the resultant was infused in 20% ethanolat 4 °C.

(2) 5 g of wet porous cellulose reacted with 5 ml epichlorohy-drin and 10 ml of 2 mol·L−1 NaOH in a three-neck roundbottom flask at 40 °C for 2.5 h, followed by adding 3.0 mlPEI, and the mixture was stirred at 90 °C for 9 h under nitro-gen gas. The product was washed with distilled water anddried at 40 °C for 6 h in vacuum.

2.3. Characterization of cellulose particles and porous PEI-cell

The morphology of cellulose particle was first observed by a JEM-100CX-II scanning electron microscope (SEM) (JEOL, Japan). Fouriertransform infrared spectra, obtained with a NEXUS 670 spectrometer(Thermo Nicolet, USA) using potassium bromide pellets, were ap-plied to characterize the porous PEI-cell. The amount of aminogroups on the PEI-cell was determined by the titration methodwith hydrochloric acid according to the following procedure: 0.2 gof dry PEI-cell was mixed with 15 ml of 0.3 mol·L−1 HCl solutionand the mixture was placed on the shaking table for 8 h. 5 ml of sam-ple in supernatant was diluted with 50 ml of redistilled water and 3drops of phenolphthalein were added into the sample as the indica-tor. The mixture was demarcated with 0.15 mol·L−1 NaOH solutionuntil the color changed from colorless to pink. The content of aminogroups (Y) is calculated by

Y ¼ C1V1−C2V2

G� 16� 100% ð1Þ

where C1 and C2 (mol·L−1) are the concentrations of HCl andNaOH solutions, respectively, V1 and V2 (L) are the volume ofHCl and NaOH solutions, respectively, and G (g) is the mass ofsample.

Please cite this article as: Z. He, et al., H. Song, Porous Spherical Cellulose Cand Fe(III) From Aqueous Solutions, Chin. J. Chem. Eng. (2014), http://dx.d

2.4. Adsorption kinetics for Cr(III) and Fe(III)

100ml of Cr(NO3)3 and FeCl3 solutionswith initial concentrations of100 and 1250 mg·L−1 was placed in two conical flasks, and 0.2 g ofporous PEI-cell particles was added into the solution separately. Thetwo conicalflaskswere placed in a shaker at 30 °C. 0.5ml of supernatantliquid was taken out from the flask at intervals. The concentrations ofCr(III) and Fe(III) were determined at 540 nm and 510 nm, respec-tively, by a TU1720 UV–visible spectrophotometer (PuxitongyongInstrumental Co. Ltd., China) after the analytes were mixed with1,5-diphenyl carbazide and phenanthroline. The standard curves ofCr(III) and Fe(III) are determined with stand solutions with gradi-ent concentrations as y = 0.00672 + 0.63298x (Rc = 0.9992) andy = 0.01381 + 0.19314x (Rc = 0.9995), respectively. The adsorp-tion amount is calculated by

Q ¼ Co−Cð Þ � Vk

mð2Þ

where Q (mg·g−1) is the adsorption amount, Co (mg·L−1) is theinitial concentration of Cr(NO3)3 or FeCl3 solution, C (mg·L−1) isthe final concentration, Vk (L) is the volume of metal salt solution,and m (g) is the mass of porous PEI-cell.

2.5. Isothermal adsorption experiment

50 ml of Cr(NO3)3 solution in a concentration range of 5–100 mg·L−1 and FeCl3 solution in a concentration range of 250–1500 mg·L−1 were transferred into different conical flasks, and 0.2g of PEI-cell particles was added. Then the conical flasks were placedon the shaker at 30, 40 and 50 °C separately to reach adsorption equi-librium. The concentrations of Cr(III) and Fe(III) were determinedbefore adsorption (Co, mg·L−1) and at adsorption equilibrium (Ce,mg·L−1) to calculate the adsorption amount per mass adsorbent(Qe, mg·g−1)

Qe ¼Co−Ceð Þ � Vi

mð3Þ

where Vi represents the solution volume (L) and m represents theabsorbent mass (g).

2.6. Investigation of major factors affecting adsorption capacity

The amount of absorbent, temperature and pH value are impor-tant factors in adsorption processes. pH values of solutions were ad-justed with HCl or NaOH andmeasured by a pHS-25 digital pH meter(Leica Instrumental Co. Ltd., China) to determine their effect on theadsorption capacity of porous PEI-cell. The adsorption experimentswere implemented with different amounts of PEI-cell particles for agiven amount of metal. The influence of temperature (20, 30, 40,50, 60 °C) was also explored for the adsorption capacity of porousPEI-cell particles.

2.7. Continuous adsorption and desorption experiments

2.02 g of PEI-cell was filled in a glass column with an innerdiameter of 1 cm by a wet packing mode. The concentrationsof Cr(III) and Fe(III) were 100 and 1250 mg·L−1, respectively,and the flow rate was controlled at 9.42 bed volume per hour(BV·h−1). Metal concentrations in the effluent were monitoredwith spectrophotometry at regular time intervals. The saturatedadsorption amount can be calculated with obtained concentra-tions and above equations.

The elution experiments were performed with 5% HCl as an elutingreagent, and the flow rate of elution was controlled at 16.35 BV·h−1.



Table 1Design and results of orthogonal experiment over PEI-cell particle

Entry Time/h Temperature/°C Concentration ofNaOH/mol·L−1

Volume ofPEI/ml

\NH2

content/%

1 8 80 1.5 2.5 1.652 8 90 2.0 3.0 3.853 8 100 2.5 3.5 3.53

3Z. He et al. / Chinese Journal of Chemical Engineering xxx (2014) xxx–xxx

The metal concentrations of eluent were determined and the elutioncurve was plotted.

After the desorption process, the adsorbent was regenerated,and the adsorption with the same metal concentrations and flowrate was repeated. With continuous adsorption and desorption onthe PEI-cell adsorbent, the reusability for the two metal ions wasevaluated.

4 9 80 2.0 3.5 3.015 9 90 2.5 2.5 2.896 9 100 1.5 3.0 2.767 10 80 2.5 3.0 3.218 10 90 1.5 3.5 3.379 10 100 2.0 2.5

K1 3.01 2.62 2.59 2.54K2 2.89 3.37 3.31 3.27K3 3.22 3.12 3.21 3.30R 0.33 0.75 0.72 0.76

3. Results and Discussion

3.1. Cellulose particle and optimal preparation conditions of PEI-cell

The size distribution of cellulose particles is shown in Fig. 1(a). Mostparticles are between 0.15 and 0.075 mm (78.51%), followed by thosesmaller than 0.075 mm (13.10%). The cellulose particles have relativelylarger specific surface and the particle size exhibits a normal distribu-tion, as shown in Fig. 1(b). SEM images are used to observe the mor-phology. Fig. 1(c) shows that the sphericity of the cellulose particle isbetter and particle size is more uniform. In Fig. 1(d), cellulose particlespresent relatively smooth surface and particle size is larger, indicatingthat amorphous region of cellulose is larger. Usually, the interactionfirst occurs in these regions, so the accessibility of objects will be higher.

Preliminary experiments show that themost effective conditions forthe preparation of PEI-cell are time (A, h), temperature (B, °C), concen-tration of NaOH (C, mol·L−1) and volume of PEI (D, ml). L9(34) orthog-onal experiments are designed to optimize these parameters, and thecontent of \NH2 is selected as the index. Table 1 indicates that the R(Xmax − Xmin) order is RD (0.76) N RB (0.75) N RC (0.72) N RA (0.33).The square of deviance of PEI volume (1.131), NaOH content (0.904)and temperature (0.867) is much larger than that of time (0.167), sothe former three are the major influencing factors. The optimized prep-aration conditions are as follows: time = 8 h, temperature = 90 °C,NaOH content = 2.0 mol·L−1, and PEI volume = 3 ml. As a result, themaximum content of amino groups was obtained as 3.85%.

Fig. 1. The size distribution of cellulose particl


3.2. FTIR spectra of porous cell-PEI

The infrared spectra of cellulose, epoxy-cellulose and PEI-cellare shown in Fig. 2. After modification of porous cellulose with epi-chlorohydrin, the adsorption peaks belonging to the stretching vi-bration of O\H and C\H bonds at 3429, 2918 and 2852 cm−1

become wider and higher in Fig. 2(a). The change indicates the occur-rence of reaction between\Cl of epichlorohydrin and\OH of celluloseand the increase of \CH2 and \CH3 groups on the surface of cellulose.Compared with the absorbance of epoxy-cellulose, the relative absor-bance at 3438 cm−1 increases obviously in Fig. 2(b), which is assignedto the stretching vibration of N\H in amine groups. These evidencesprove that PEI polymer is grafted on a cellulose surface and the adsor-bent of PEI-cell is successfully synthesized.

e (a, b) and SEM images of PEI-cell (c, d).



Fig. 2. Infrared spectra of cellulose, epoxy-cellulose and PEI-cell.


3.3. Adsorption mechanism of PEI-cell

According to the structure of porous PEI-cell, a single PEI chain hasmore than one attachment site, lowering the rigidity of cross-linkedamine groups. Therefore, PEI cross-linked with the cellulose is superioron the capacity and selectivity towards metal ions.

3.3.1. Adsorption kineticsThe kinetic curves of the PEI-cell towards Cr(III) and Fe(III) are

shown in Fig. 3. The adsorption rate of the adsorbent is fast, and the in-crease in absorbed amount for Cr(III) and Fe(III) is not obvious after 1 h.Therefore, the PEI-cell adsorbent could capture the twometal ions fromtheir aqueous solutions efficiently. The experimental data are correlatedwith the first and second order kinetic models. Table 2 shows that thesecond order model is more suitable to describe the adsorption fortwometal ions, so the adsorption rate is relatedwith the concentrationsof metal ions and the major interaction mechanism can be ascribed tochemical adsorption.

Fig. 3. The kinetic curve of the PEI-cell for Cr(III) and Fe(III).

Table 2Kinetic model parameters from equation fittings

Metal ion Kinetic order Regression equation Correlation coeffic

Cr(III) 1 y = 4.02611 − 0.07345x 0.996132 y = 0.12734 + 0.01759x 0.99927

Fe(III) 1 y = 6.31364 − 0.06329x 0.929162 y = 0.05737 + 0.00242x 0.98969


3.3.2. Adsorption isothermsThe adsorption isotherms of PEI-cell for Cr(III) and Fe(III) at 30, 40

and 50 °C are shown in Fig. 4. Equilibrium adsorption amounts of thetwo metal ions increase quickly with the increase of equilibrium con-centration and then decrease, demonstrating that the adsorption pro-cess reaches saturation. The composite material of PEI-cell has a verystrong adsorption capacity for Cr(III) and Fe(III), so there exists high af-finity between metals and PEI-cell particles (chelation and hydrogenbond interactions). The interactions can be proved by comparing IRspectra for PEI-cell and PEI-cell adsorbed with metal ions. After the ad-sorption of Cr(III) and Fe(III), both the intensity andwave number of ab-sorption peaks at 3438 and 1641 cm−1 decrease in different degrees.The stretching and bending vibrations of amino groups are restrictedfor hydrogen bond and chelation interactionswithmetal ions. In furtherinvestigation, both Langmuir and Freundlich isotherms are used to cor-relate the equilibrium data, and regression coefficients of the latter arelarger than those of the former, so the Freundlich adsorption model ismore suitable to describe the adsorption. The linear regression equa-tions and coefficients of Cr3+ and Fe3+ are summarized in Table 3.

3.4. Factors affecting adsorption capacity

3.4.1. Effect of pH value on adsorption capacityAdsorption capacities of the porous PEI-cell for Cr(III) and Fe(III) are

different in different pH values, as shown in Fig. 5(a). The pHvalue has agreat influence on the adsorption property. In basic solution, Cr(III) andFe(III) will precipitate as Cr(OH)3 and Fe(OH)3, so the adsorption at pHvalue above 7 is not investigated. At very low pH value, the concentrationof H+ is much higher than that of metal ions. The amine groups on PEI-cell surface would preferentially combine with H+ to form \NH3

+,which is disadvantageous for the interaction between it and metal ions.At higher pH value, the number of protonated amine groups would beless and metal ions have more opportunities to compete with H+ forthe combination with \NH2. The chelation becomes more significantbetween PEI-cell and metal ions, increasing the adsorption capacity.However, Cr(III) and Fe(III) would begin to precipitate at pH value

ient Standard deviation Calculated adsorptionamount/mg·g−1

Actual adsorptionamount/mg·g−1

0.14812 56.04 61.740.04289 56.85 61.740.56550 552.05 348.230.02048 413.22 348.23



Fig. 4. Adsorption isotherms of PEI-cell for Cr(III) and Fe(III) at 30, 40 and 50 °C.

Table 3Linear regression of Freundlich adsorption

Metal ion Temperature/K Regression equation Regression coefficient

Cr(III) 303 y = 1.6531 + 0.6800x 0.9722313 y = 0.9776 + 0.7612x 0.9764323 y = 0.3520 + 0.8855x 0.9736

Fe(III) 303 y = 1.1643x − 2.4817 0.9808313 y = 1.1769x − 2.7210 0.9759323 y = 1.3603x − 4.1448 0.9682

Fig. 5. Effect of pH (a), temperature (b) and abs



beyond 5, as a result the adsorption amountwould decrease. Thusweaklyacidic condition (pH= 5) is suitable for the adsorption of the two metalions.

3.4.2. Effect of temperature on adsorption capacity and thermodynamicstudy

Fig. 5(b) shows the adsorption capacity at various temperatureswith the saturation adsorption amount as the index. The adsorption

orbent amount (c) on adsorption capacity.



Table 4Thermodynamic parameters for Cr(III) and Fe(III)

Metalion

ΔH/kJ·mol−1

ΔG/kJ·mol−1 ΔS/J·mol−1 · K−1

303 K 313 K 323 K 303 K 313 K 323 K

Fe(III) −23.825 −3.704 −3.419 −2.986 −66.406 −65.195 −64.517−29.375 −84.723 −82.927 −81.700−7.984 −14.125 −14.585 −15.474

Cr(III) −8.684 −2.164 −2.211 −1.974 −21.518 −20.681 −20.774−2.670 −1.677 −1.466 −2.155−3.158 −3.281 −3.026 −3.666

Table 5Comparison among reported polysaccharide and adsorbents containing\NH2

Metal ion Type of adsorbents Adsorptionamount/mg·g−1

Reference

Cr(III) Sugarcane pulp residue 3.43 [9]Sugarcane bagasse modifiedwith sodium hydroxide andcitric acid

58 [12]

Amino functionalized mesoporousnanofiber membrane

97 [27]

Natural and crosslinked chitosanmembranes

7.0–50.0 [28]

Fe(III) Thiourea cross-linked chitosan 54 [14]Hazelnut hull (lignocellulose) 13.59 [16]Chitosan–tripolyphosphate beads 13.72 [17]Polyacrylamide grafted activatedcarbon

6.15 [19]


capacity of PEI-cell particles increases with temperature at the begin-ning. When the temperature reaches 30 °C for Cr(III) and 40 °C forFe(III), the adsorption capacity achieves themaximum. Further increaseof temperature reduces the adsorption amounts of the two metal ionsobviously.

Table 4 provides the thermodynamic parameters for Cr(III) andFe(III) at various temperatures. As the support for the conclusion fromadsorption isotherms, the data in Table 4 also indicate that the adsorp-tion process is an exothermic process, so higher adsorption temperatureis unfavorable. The values of ΔG are negative at these temperatures,confirming that the adsorption is spontaneous and thermodynamicallyfavorable. Negative values of ΔS prove the decrease of randomness atthe solid–solution interface during adsorption, indicating that themovement of metal ions is restricted after adsorption.

3.4.3. Effect of absorbent amount on adsorption capacityThe amount of adsorbent is another important factor on the adsorp-

tion process for metal ions. Fig. 5(c) shows the adsorption performancefor the two metal ions with 0.01–0.30 g adsorbents for 50 ml of100 mg·L−1 Cr(III) and 1250 mg·L−1 Fe(III) solutions. The resultsshow that the adsorption capability is the greatest with 0.2 g of PEI-cell adsorbent.

3.4.4. The saturation adsorption amountUnder optimal dynamic adsorption conditions, the breakthrough ex-

periment of dynamic adsorption was also performed. The sample ofmetal solutionwas continuously loaded in the column of PEI-cell adsor-bent, and the breakthrough point would appear when the adsorptionwas saturated. The steep slope of breakthrough curve indicates a rapidmass transfer, which is accorded with the static kinetic study (shownin Fig. 3). At the breakthrough point, the adsorption capacity wasobtained as 83.98 mg·g−1 for Cr(III) and 377.19 mg·g−1 for Fe(III). Inorder to study the contribution of PEI groups for the improvement ofadsorption, unmodified cellulose and PEI-cell were compared. The satu-ration adsorption amount of the former was only 9.78 mg·g−1 forCr(III) and 14.29 mg·g−1 for Fe(III). The results indicate that a greatnumber of attachment sites in PEI chains play an important role.Table 5 summarizes themaximum adsorption amount of similar adsor-bents for Cr(III) and Fe(III).

3.5. Desorption and recycle of the porous PEI-cell

Fig. 6(a) shows the elution curves of Cr(III) and Fe(III) from PEI-cellwith 5%HCl screened from conventional solvents as the eluent at a flowrate of 16.35 BV·h−1 in the column packed with PEI-cell particles. Theshape of elution curve is cuspate and little tailing appears, showing rel-atively good elution performance. Cr(III) and Fe(III) can be eluted fromthe PEI-cell with desorption ratios of 98.06% and 89.51% with 15 and40ml HCl, respectively.When the elutionwas operated at 40 °C, the de-sorption ratio could reach 99.88% and 97.74%. Absolute values of thechange in adsorption enthalpy (ΔH) are small (see Table 4), whichalso indicates that the desorption could be easily completed. The excel-lent regeneration property is meaningful to reduce the cost in adsorp-tion application. In order to investigate and evaluate the reusability of


PEI-cell, the changing trend of adsorption amount and desorptionratio for the two metal ions are shown in Fig. 6(b, c), with the porousPEI-cell possessing an acceptable adsorption capacity after being reused6 times. No obvious change is found in its morphology.

4. Conclusions

The macromolecule polyethyleneimine was grafted on the porouscellulose particles via the introduction of epoxy group and open loop re-actions, and the functional adsorbent of PEI-cell was successfully pre-pared. The adsorption ability of PEI-cell for Cr(III) and Fe(III) is goodwith hydrogen bond interaction and chelation interaction. The main fac-tors related with the adsorption ability for Cr(III) and Fe(III) include pHvalue, temperature and amount of adsorbent. The best adsorption capac-ity appears at pH = 5, at 30 °C for Cr(III) and 40 °C for Fe(III). The ad-sorption kinetics, isotherms and thermodynamic parameters aresystematically studied to explore the interaction mechanism betweenmetal ions and absorbent. The PEI-cell particles present a good regener-ation behavior. Thus the cellulose adsorbent grafted with functionalpolymer shows better adsorption and desorption performance thansimilar adsorbents reported and it is feasible and promising to removeCr(III) and Fe(III) from aqueous solutions in wastewater treatment.

NomenclatureC final concentration of Cr(NO3)3 or FeCl3 solution, mg·L−1

C1 concentration of HCl solution, mg·L−1

C2 concentration of NaOH solution, mg·L−1

Ce concentrations of Cr(III) or Fe(III) at adsorption equilibrium,mg·L−1

Co initial concentration of Cr(NO3)3 or FeCl3 solution, mg·L−1

G mass of sample, gΔG free energy, kJ·mol−1

ΔH enthalpy change, kJ·mol−1

m mass of porous cell-PEI, gQ adsorption amount, mg·g−1

Qe adsorption amount per unit mass adsorbent at adsorptionequilibrium, mg·g−1

RA range value (X max – X min) of reaction timeRB range value (X max – X min) of temperatureRC range value (X max – X min) of concentration of NaOHRD range value (X max – X min) of volume of PEIΔS entropy change, J·mol−1·K−1

V1 volume of HCl solution, LV2 volume of NaOH solution, LVi volume of Cr(III) or Fe(III) solution in isothermal adsorption

experiment, LVk volume of Cr(III) or Fe(III) solution in adsorption kinetic

experiment, LY content of amino groups, %



Fig. 6. Elution curves of Cr(III) and Fe(III) and reusability of PEI-cell.


References

[1] V.K. Gupta, A. Rastogi, A. Nayak, Studies on the removal of hexavalent chromiumfrom aqueous solution using a low cost fertilizer industry waste material, J. ColloidInterface Sci. 342 (2010) 135–141.

[2] A. Selatnia, A. Boukazoula, N. Kechid, M.Z. Bakhti, A. Chergui, Biosorption of Fe3+

from aqueous solution by a bacterial dead Streptomyces rimosus biomass, ProcessBiochem. 39 (2004) 1643–1651.

[3] A. Demirbas, Heavy metal adsorption onto agro-based waste materials: a review, J.Hazard. Mater. 157 (2008) 220–229.

[4] N. Pourreza, J. Zolgharnein, A.R. Kiasat, T. Dastyar, Silica gel–polyethylene glycol as anew adsorbent for solid phase extraction of cobalt and nickel and determination byflame atomic adsorption spectrometry, Talanta 81 (3) (2010) 773–777.

[5] X. Xu, B.Y. Gao, X. Tang, Q.Y. Yue, Q.Q. Zhong, Q. Li, Characteristics of cellulosicamine-crosslinked copolymer and its sorption properties for Cr(VI) from aqueoussolutions, J. Hazard. Mater. 189 (2011) 420–426.

[6] N. Yeddou, A. Bensmaili, Equilibrium and kinetic modelling of iron adsorptionby eggshells in a batch system: effect of temperature, Desalination 206 (2007)127–134.

[7] P.G. Wightman, J.B. Fein, Iron adsorption by bacillus subtilis bacterial cell walls,Chem. Geol. 216 (2005) 177–189.

[8] Y. Wu, S.Z. Zhang, X.Y. Guo, H.L. Huang, Adsorption of chromium(III) on lignin,Bioresour. Technol. 99 (16) (2008) 7709–7715.

[9] Z.H. Yang, S. Xiong, B. Wang, Q. Li, W.C. Yang, Cr(III) adsorption by sugarcane pulpresidue and biochar, J. Cent. South Univ. 20 (5) (2013) 1319–1325.

[10] A. Shoaib, N. Aslam, M.M. Athar, S. Akhtar, Nafisa, S. Khurshid, Removal of Cr(III)through bread mold fungus, Pol. J. Environ. Stud. 22 (4) (2013) 1171–1176.

[11] S. Tangjuank, N. Insuk, V. Udeye, J. Tontrakoon, Chromium (III) sorption fromaqueous solutions using activated carbon prepared from cashew nut shells, Int. J.Phys. Sci. 4 (8) (2009) 412–417.

[12] V.C.G.D. SantosI, A.D.P.A. Salvado, D.C. Dragunski, D.N.C. Peraro, C.R.T. Tarley, J.Caetano, Highly improved chromium (III) uptake capacity in modified sugarcanebagasse using different chemical treatments, Quim. Nova 35 (8) (2012), http://dx.doi.org/10.1590/S0100-40422012000800021.

[13] C.H. Fan, Y.C. Zhang, H.R. Ma, Co-adsorption behavior of methylene blue (MB) andCr(III) on synthesized zeolite from fly ash: II. Competitive adsorption mechanism,Chin. J. Environ. Eng. 8 (3) (2014) 1025–1028.

[14] J. Dai, F.L. Ren, C.Y. Tao, Adsorption behavior of Fe(II) and Fe(III) ions onthiourea cross-linked chitosan with Fe(III) as template, Molecules 17 (4)(2012) 4388–4399.


[15] C.Y. Abasi, A.A. Abia, J.C. Igwe, Adsorption of iron (III), lead (II) and cadmium (II)ions by unmodified Raphia palm (Raphia hookeri) fruit endocarp, Environ. Res. J. 5(3) (2011) 104–113.

[16] S. Ali, R.S. Masoud, A. Hamed, Removal of Fe(III) ions from aqueous solution by ha-zelnut hull as an adsorbent, Int. J. Ind. Chem. 3 (2012), http://dx.doi.org/10.1186/2228-5547-3-4.

[17] M.A. Correa-Murrieta, J. Lopez-Cervantes, D.I. Sanchez-Machado, R.G. Sanchez-Duarte, J.R. Rodriguez-Nunez, J.A. Nunez-Gastelum, Fe(II) and Fe(III) adsorptionby chitosan–tripolyphosphate beads: kinetic and equilibrium studies, J. WaterSupply Res Technol. 61 (6) (2012) 331–341.

[18] D.K. Singh, S. Mishra, Synthesis and characterization of Fe(III)-ion imprinted poly-mer for recovery of Fe(III) from water samples, J. Sci. Ind. Res. 69 (10) (2010)767–772.

[19] A.A. El-Zahhar, S.E.A. Sharaf El-Deen, R.R. Sheha, Sorption of iron from phosphoricacid solution using polyacrylamide grafted activated carbon, J. Environ. Chem. Eng.1 (3) (2013) 290–299.

[20] H. Wang, Y.F. He, W.J. He, Y. Wang, R.M. Wang, Modification of cellulose and itsapplication in wastewater treatment, Techno. Water Treat. 38 (5) (2012) 1–6.

[21] T. Tan, X.C. Xu, C. Yang, D.M. Yang, X.F. Zhu, Preparation ofmodified rice straw fibersand its adsorption of Fe3+, Cu2 +, Ni2+, Zn2+ in plating wastewater,Mod. Chem. Ind.31 (6) (2011) 45–47.

[22] B.J. Gao, Y.B. Li, Z.P. Chen, Adsorption behavior of functional grafting particlesbased on polyethyleneimine for chromate anions, Chem. Eng. J. 150 (2009)337–343.

[23] M. Amara, H. Kerdjoudj, Modification of the cation exchange resin properties by im-pregnation in polyethyleneimine solutions: application to the separation of metallicions, Talanta 60 (2003) 991–1001.

[24] V.K. Verma, S. Tewari, J.P.N. Rai, Ion exchange during heavy metal biosorption fromaqueous solution by dried biomass of macrophytes, Bioresour. Technol. 99 (2008)1932–1938.

[25] G.H. Pino, L.M.S. De Mesquita, M.L. Torem, G.A.S. Pinto, Biosorption of heavy metalsby powder of green coconut shell, Sep. Sci. Technol. 41 (2006) 3141–3153.

[26] S.Y. Kang, J.U. Lee, K.W. Kim, Biosorption of Cr(III) and Cr(VI) onto the cell surface ofPseudomonas aeruginosa, Biochem. Eng. J. 36 (2007) 54–58.

[27] A.A. Taha, J.L. Qiao, F.T. Li, B.R. Zhang, Preparation and application of amino function-alized mesoporous nanofiber membrane via electrospinning for adsorption of Cr3+

from aqueous solution, J. Environ. Sci. 24 (4) (2012) 610–616.[28] E. Meneghetti, P. Baroni, R.S. Vieira, M.G.C. Silva, M.M. Beppu, Dynamic adsorption

of chromium ions onto natural and crosslinked chitosanmembranes for wastewatertreatment, Mater. Res. 13 (1) (2010) 89–94.


http://refhub.elsevier.com/S1004-9541(14)00080-9/rf0005





























http://dx.doi.org/10.1590/S0100-40422012000800021










http://dx.doi.org/10.1186/2228-5547-3-4

http://dx.doi.org/10.1186/2228-5547-3-4












































porous spherical cellulose carrier modified with polyethyleneimine and its adsorption for cr(iii)...

Documents