Zr(OH)_4沉淀物对铬鞣废水Cr^(3+)的吸附实验

Adsorptive removal of Cr^(3+) from chromium tanning wastewater using zirconium hydroxide

用Zr(OH)4模拟锆鞣废水中的沉淀物作为吸附剂处理低浓度铬鞣废水,考察了吸附时间、Zr(OH)4投加量、溶液pH值、盐离子(Na+、Ca2+)浓度等因素对Cr3+去除效果的影响,结果表明,在pH<4.5时,Cr3+的去除为吸附过程,当pH>4.5后,为沉淀和吸附混合过程;Cr3+在Zr(OH)4上的吸附过程可以用Freundlich模型进行模拟;Na+和Ca2+对铬的吸附有一定的抑制作用.实际锆鞣废水中的杂质成分与Cr3+产生竞争吸附,使去除率略有降低,最低去除率可达71.29%以上.

Zirconium hydroxide was used to model the precipitates in chromium tanning wastewater, and was utilized as an adsorbent to remove Cr3＋ from the tanning wastewater. The influence of adsorption time, dosage of zirconium hydroxide, pH, concentrations of salt ion （Na＋、Ca2＋ ） on adsorption effect was investigated. The experiment results indicate that trivalent chromium was removed effectively by zirconium hydroxide, and the adsorption process could be simulated by Freundlich model. At pH 〈 4.0,Cr3＋ was removed by adsorption. When pH 〉 4.0, Cr3＋was removed by precipitation and adsorption. Salt ions （ Na＋、Ca2＋ ） had inhibition effect on Cr3＋ adsorption. Removal ofCr3＋ from tanning wastewater by zirconium hydroxide was evaluated. The removal rate decreased slightly due to the competitive adsorption of impurities in the tanning wastewater, but the lowest removal rate was still 71.29%.