高岭土在Cd^2＋^/对硝基苯酚复合污染体系中的吸附行为

在研究高岭土吸附单体污染物Cd2＋和对硝基苯酚的基础上,研究了高岭土在Cd2＋/对硝基苯酚复合污染体系中的吸附行为.实验结果表明,单一的对硝基苯酚和Cd2＋在高岭土上的吸附与溶液pH值和初始浓度密切相关,对硝基苯酚的吸附以分配作用为主,而Cd2＋则以表面吸附作用为主;在复合体系中,低浓度时的对硝基苯酚在高岭土上的吸附以表面吸附为主,从而与Cd2＋产生激烈的竞争吸附,使对硝基苯酚的去除率从56.34%上升到71.23%,而Cd2＋受对硝基苯酚竞争吸附的影响,在高岭土上的吸附被抑制,去除率从82.29%降到60.19%;高浓度时对硝基苯酚在高岭土上的吸附以分配作用为主,因此Cd2＋的存在对对硝基苯酚影响不大.

Adsorption Effect of Kaolin on PNP/Cd2+ Combined Pollution

On the basis of the research of kaolin’s adsorption of the Cd2＋ and the PNP as monomer pollutants,the adsorption behavior of kaolin in the Cd2 ＋/PNP complex pollution system was studied.The results show that the adsorption of monomer PNP or Cd2＋ on kaolin is closely related to pH and ionic strength.The adsorption of PNP is mainly due to distributional effect,whereas the adsorption of Cd2＋ is mainly due to surface adsorption effect.In the composite system,kaolin’s adsorption of low-concentrated PNP is mainly surface adsorption,thus producing an intense adsorption competition between PNP and Cd2＋.As a result,the removal rate of PNP increases from 56.34% to 71.23%;whereas the adsorption of Cd2＋,affected by the competition,is inhibited.Consequently,the removal rate of Cd2＋ drops from 82.29 percent to 60.19 percent.Kaolin’s adsorption of high-concentrated PNP is mainly due to distributional effect,so the presence of Cd2＋ has little influence on PNP.