活性炭表面功能化及对镉离子的吸附性能

Surface functionalization of activated carbon and adsorption property of cadmium ion

活性炭的吸附性能与其表面化学密切相关,为讨论活性炭表面化学性质对镉离子吸附特性的影响,对表面功能化活性炭对镉离子的吸附性能进行了研究。对活性炭进行氨气还原改性处理以实现表面功能化,改性后活性炭含氧官能团数量减少,零电荷点增大,成功在活性炭上引入含氮官能团。氨改性后活性炭对水溶液中Cd(Ⅱ)的去除率明显提高,该吸附是一个自发且吸热的过程。通过XPS分析改性前后、吸附前后活性炭表面化学性质,探明Cd(Ⅱ)主要通过离子交换和配位络合两种作用方式在活性炭上吸附,与Cd(Ⅱ)发生络合作用的是活性炭表面含氧官能团和含氮官能团。

Adsorption property goes together with surface chemistry of activated carbon.In order to study the effect of surface chemistry properties of activated carbon on adsorption, adsorptive performance of activated carbon with surface functionalization for adsorbing cadmium ion from aqueous solution was investigated.Activated carbon was modified with NHfor surface functionalization.Number of oxygen-containing functional groups decreased and the pH value of point of zero charge increased after modification.Nitrogen-containing functional groups was introduced onto the surface of activated carbon.Activated carbon modified with NHshowed an increased adsorption capacities in removal of Cd(Ⅱ).The adsorption was a spontaneous and endothermic process.Surface chemical properties of activated carbon before and after modification and adsorption were characterized by XPS.It can be seen that the adsorption mechanism of Cd(Ⅱ) included ion exchange and formation of coordination complexes.It shows that just the oxygen-containing and nitrogen-containing functional groups on the surface of activated carbon are complexed with Cd(Ⅱ).