不同组成活性污泥胞外聚合物吸附Cd2+、Zn2+特征

以蛋白质和糖含量比分别为2.5∶1、7∶1和9∶1的3种活性污泥胞外聚合物(extracellular polymeric substances, EPS)EPS1、EPS2、EPS3作为吸附剂，研究其对水中Cd²⁺、Zn²⁺的吸附效能.结果表明，EPS对Cd²⁺和Zn²⁺的吸附与其组成有关，EPS1、EPS2和EPS3对Cd²⁺和Zn²⁺吸附量分别约为19.5、　27、　17　mg/g和40.5、 47.5、 37　mg/g. 3种胞外聚合物对Cd²⁺、Zn²⁺吸附过程可在1 h内快速平衡.动力学拟合结果表明，EPS1对2种重金属的吸附速率最快，而EPS2对Cd²⁺、Zn²⁺的平衡吸附容量最高.Freundlich和Langmuir方程均可描述3种EPS对Cd²⁺、Zn²⁺的吸附过程，方程参数拟合结果表明2种金属同EPS之间存在多种作用方式.3种EPS的吸附热力学方程拟合系数均表明EPS对Zn²⁺的吸附稳定性、吸附能力和亲和力均比对Cd²⁺的吸附强；当EPS中糖所占比例增加时，其对重金属的吸附能力也提高，表明糖在吸附过程中起着重要作用.

Adsorption Characteristics of Cd2+ and Zn2+ by Extracellular Polymeric Substances with Varied Constituents from Activated Sludge

The adsorption characteristics of phenol, p-chlorophenol and p-nitrophenol in wastewater by activated carbon fiber (ACF) were studied. The surface properties of ACF were characterized by scanning electron microscopy (SEM). The thermodynamic characteristics and mechanism of phenol, p-chlorophenol and p-nitrophenol adsorption on ACF were investigated by using the bottle-point technique. The results showed that the adsorption speed was fast, and ACF had good adsorption properties when pH<7. On the same condition, the order of removal efficiency were: phenol (87%)<p-chlorophenol (96%) <p-nitrophenol (99%). All the adsorptions are physical adsorption, and the adsorption process were spontaneous exothermic reaction. All the adsorption isotherms can be well represented by Dubinin-Radushkevich equation and the sorption process were spontaneous exothermic reaction.