活性炭对汞离子的吸附动力学研究

摘要

Activated carbon with micropores was prepared from coconut carbon using steam activation by secondary activation. N2-adsorption isotherm, mathematical models such as D-R equation and BJH methods were used to characterize the properties of the prepared activated carbons. With mercury chloride as pollution targets, the adsorption properties of activated carbon for Hg2+were investigated. The results indicated that the adsorption of Hg2+ was obviously influenced by surface area and pore structure of activated carbon. The process of adsorption was a two speed process with rapidly adsorption and slowly adsorption coexisting. This process could be well described by Lagergren pseudo second order model. The adsorption isotherm experiment showed that adsorption of Hg2+ on activated carbon is an exothermic and single molecular layer adsorption process. It could be fitted by Langmuir isotherm model.%以椰壳活性炭为原料,采用水蒸气法二次活化制备得到了微孔含量丰富的椰壳活性炭,其亚甲基蓝吸附值165 mg/g,碘吸附值1090 mg/g。采用氮气吸附等温线对其比表面积和孔结构进行了表征。以氯化汞为污染目标物,考察了活性炭对于Hg2+的吸附性能。结果表明,活性炭对Hg2+的吸附量与其比表面积以及孔结构有关。吸附动力学实验表明活性炭吸附是一个快速吸附和缓慢吸附共存的双速过程,可以用Lagergren伪二级速率方程进行拟合；吸附等温线实验表明活性炭吸附Hg2+是一个放热的过程,属于单分子层吸附,符合Langmuir吸附等温式。