酒石酸钾钠(PST)对纳滤处理重金属废水的强化机理  

Mechanism for enhancement in nanofiltration for treatment of heavy metal wastewater with addition of potassium sodium tartrate(PST)

作　　者：王光春[1] 李振山[1,2] 吴双[1] 

机构地区：[1]北京大学深圳研究生院环境与能源学院,深圳市重金属污染控制与资源化重点实验室,深圳518055 [2]北京大学环境工程系,水沙科学教育部重点实验室,北京100871

出　　处：《环境工程学报》2016年第8期4125-4133,共9页Chinese Journal of Environmental Engineering

基　　金：国家水体污染控制与治理科技重大专项(2010ZX-07212-008);中国清洁发展机制基金赠款项目(1214073)

摘　　要：在已有纳滤处理重金属实验中,发现适当添加酒石酸钾钠可以使金属去除率增大的同时膜通量没有明显降低,而且纳滤膜表面接触角与膜通量呈稳定的负线性关系。采用X-射线(单晶)衍射法对酒石酸钾钠(PST)与Cd^(2+)、Ni^(2+)、Zn^(2+)、Cu^(2+)4种金属离子的络合配位方式进行分析。通过对晶体结构和键长键角等参数的分析表明,酒石酸钾钠主要通过羧基氧原子和邻位羟基氧原子与金属离子鳌合配位形成五元鳌合环;络合配位的中心金属离子Ni^(2+)、Zn^(2+)和Cu^(2+)是六配位形式,而Cd^(2+)是七配位形式。进一步通过配位分析方法计算了不同配比下配合物水分子量的大小,发现其变化特征与纳滤膜通量的变化趋势相似;金属离子络合物体积变化受到配位键长键角和酒石酸根配位数的控制,其变化特征与纳滤截留率变化一致。说明络合物的配位水分子量和配位体积大小2个参数能够分别解释PST强化纳滤处理重金属膜通量和截留率的变化特征。Previous study suggested that the appropriate addition of potassium sodium tartrate（ PST） can enhance the removal efficiency of metal ions from wastewater during nanofiltration without causing a decline in permeate flux. Furthermore,negative linear correlation was observed between the contact angle of a nanofiltration membrane surface and permeate flux. In this study,the coordination modes of PST with the four metal ions（ Cd^2＋,Ni^2＋,Zn^2＋and Cu^2＋） were analyzed by X-ray crystallography. By analyzing the crystal structure,bond lengths,and bond angles,PST chelated to the centers of the metal ions through a carboxylate oxygen atom and an ortho-hydroxyl oxygen atom,forming a five-membered ring. The coordination metal ions of Ni^2＋,Zn^2＋,and Cu^2＋were hexacoordinated,whereas Cd^2＋was seven-coordinated. Based on the calculation of coordinated water molecules in different proportions with the coordination analysis,it was found that the variation characteristics are similar to that of permeate flux. Coordination volume was controlled by bond lengths,bond angles,and the degree of coordination; and the variation characteristics were consistent with those of rejection. The results of this study indicate that coordinated water molecules and coordination volume,respectively,explain variation characteristics of permeate flux and rejection in nanofiltration enhanced by PST.

关 键 词：纳滤 重金属 酒石酸钾钠 X射线(单晶)衍射法 络合 配位 

分 类 号：X703[环境科学与工程—环境工程]