褐煤对Cr(Ⅵ)模拟废水的吸附特性

Experimental research on the removal of Cr(Ⅵ) from wastewater using lignite coal

采用低温氮气物理吸附仪、红外光谱仪及扫描电镜对内蒙褐煤的孔结构、表面官能团及表面特性进行表征，进一步考察了褐煤投加量、吸附时间、溶液pH、实验温度对褐煤脱除溶液中Cr （Ⅵ）性能的影响。结果表明，内蒙褐煤具有层状结构，孔径主要分布在2～24 nm之间，有利于溶液中Cr（Ⅵ）的迁移和吸附；表面较丰富的含氧官能团在较高实验温度下可能改变溶液中的H＋含量，促进褐煤对Cr（Ⅵ）脱除；实验条件下褐煤对Cr（Ⅵ）的脱除率和脱除容量分别可达72％和0．047 mg／g，脱除率随褐煤添加量增大的特性有利于煤炭地下气化地下水污染的自修复；褐煤对Cr（Ⅵ）的脱除符合Freundlich等温吸附方程及假一级动力学方程，为多分子层物理吸附，其等温吸附方程为Q＝0．01572C0．63751。

The porous characteristics and functional groups of the lignite coal were characterized by apply-ing automatic specific surface and porosity analyzer and Fourier transform infrared spectroscopy （ FTIR） , respectively .The removal effects of adsorbent mass ,adsorption time ,pH and experimental temperature on Cr（Ⅵ） in the solution were further investigated .The results show that： pore size distribution in 2 -24 nm of lignite coal and layer structure were observed ,pore size of which were in favour of the migration and the adsorption of Cr （Ⅵ）;Hydrogen ion content in solution could be changed by surface oxygen-en-riched functionalities of lignite at high experimental temperatures , contributable to removal of Cr 6＋.The highest Cr 6＋removal rate of 72%and adsorption capacity of 0 .047 mg/g could be obtained under experi-mental conditions ,and the fact that removal rate increases with lignite adding amount were meaningful for self-remedy of groundwater pollution caused by underground coal gasification .The removal rule of Cr（Ⅵ） by lignite fit well with the Freundlich adsorption model and the pseudo-first-order kinetics ,named physical polymolecular layer adsorption ,and the equation can be calculated as Q=0.015 72C0.637 51 .