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Cr (VI) removal by a new type of anion exchange resin DEX-Cr: Adsorption affecting factors, isotherms, kinetics, and desorption regeneration

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Abstract

The adsorption of Cr (VI) by an anion exchange resin of DEX-Cr, which contains tertiary and quaternary amine groups, was studied under varying experimental conditions that include pH, resin amount, contact time, and temperature. Batch-shaking experiments were conducted to evaluate the performance of DEX-Cr in removing Cr (VI). The ion-exchange process indicated that the maximum removal could be achieved at pH of 3 and an initial Cr (VI) concentration of 2200 mg/L. The results of adsorption equilibrium experiments fit well with Freundlich isotherm, showing that the adsorption was a multilayer process. Thermodynamic parameters indicated that the uptake of Cr (VI) by DEX-Cr was spontaneous and endothermic. Kinetic experimental data followed the pseudo first-order equation. The desorption study revealed that adding NaCl to NaOH solution helped to improve elution efficiency dramatically. The elution results had a relationship with the mass fraction of NaCl to NaOH, higher mass fraction contributed to higher elution efficiency. The elution efficiency improved slightly with the number of times of desorption increasing, which indicates that the resin had potential in cyclic utilization. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 387–393, 2015

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