| The removal of Cr(Ⅵ) in water was studied by acid modified bentonite in the form of packing column using iron powder and quartz sand in this paper. The dynamic adsorption model was developed in modified bentonite, iron powder and quartz sand, which provided adsorption kinetics and thermodynamics experimental parameters. Natural bentonite and modified bentonite were analyzed by XRD(X-Ray Diffraction), SEM(scanning electron microscope) and surface measuring instrument. The following conclusions were obtained from this experiment.1) Compared with natural bentonite, the XRD data of acid modified bentonite show that the peak value of6-2Thesc-scade enhances, and the other peak values are not changeable. The specific surface area, pore volume and average pore size are increased significantly. The experimental results demonstrate adsorbability of bentonite can be improved by acid modification.2) Adsorption kinetic parameters of Cr(Ⅵ) adsorbed by bentonite:K=2.53g/μmol·min, q=0.0152umol/g, R2=0.98.3) Langmuir parameters for adsorption of Cr(Ⅵ) by bentonite:q=1.046μg/g, KL=15.93L/μg. Correlation coefficient of Freundlich sorption isotherm did not fit very well. The results showed that the adsorption process of chromium on bentonite belonged to mono-molecular surface adsorption which was endothermic and spontaneous processes, meanwhile belonged to physical adsorption. The reaction was not reversible and desorption took place less readily.4) It was found that the removal rate of chromium on modified bentonite was fast. The removal rate was more than99.9%when adsorption time was lmin. Results showed that the removal efficiency of chromium on modified bentonite increased more significantly than natural bentonite. 5) Heavy metal chromium(VI) could be continuously adsorbed by bentonite and modified bentonite in dynamic condition using continuous-flow inflow water. |
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