纳滤去除微污染水中Pb^(2+)、Cd^(2+)的影响因素

Influencing Factors of Nanofiltration for Removing Pb^(2+) and Cd^(2+) from Slightly Polluted Water

随着污废水排放的增加,饮用水水源水体中重金属离子超标的现象时有发生,尤其是铅、镉等危害较大的重金属离子.此类重金属具有毒效长、不可降解等特点,由于重金属离子的特有性质,采用传统处理方法难以达到安全饮用水标准.本文采用自行设计的纳滤小试装置,选用正交试验测试VNF-4040K与ESNA1-4040两支纳滤膜对微污染水中Pb^(2+)、Cd^(2+)的去除效果,并采用幂函数多项式拟合试验数据表征试验指标与各因素的函数关系,考察了进水浓度、电导率、p H值、膜通量及回收率对纳滤去除重金属离子效果的影响.通过试验得出:VNF-4040 K与ESNA1-4040 2支纳滤膜对Pb^(2+)、Cd^(2+)的去除均受到操作条件的影响,进水浓度的变化对去除率影响较大,在浓度倍数为1倍时达到最高,分别为94.76%,84.49%,97.64%,95.69%;膜通量与2支纳滤膜对重金属离子(Pb^(2+)、Cd^(2+))截留呈正相关;而电导率、回收率与去除率呈负相关,碱性条件有利于纳滤膜对重金属离子(Pb^(2+)、Cd^(2+))的去除;ESNA1-4040膜对Pb^(2+)与Cd^(2+)的去除率均优于VNF-4040K膜.

With the increase of sewage and wastewater discharge,heavy metal ions in drinking water source water exceed the standard from time to time.Due to the unique nature of heavy metal ions,it is difficult to meet the safe drinking water standard by traditional treatment methods.In this paper,a self-designed nanofiltration pilot plant was used to test the removal effects of two nanofiltration membranes VNF-4040K and ESNA1-4040 on Pb2 and Cd^(2+)in micro polluted water by orthogonal test.The power function polynomial was used to fit the test data to characterize the functional relationship between the test indicators and various factors.The effects of influent concentration,conductivity,pH value,membrane flux and recovery on the removal effect of heavy metal ions by nanofiltration were investigated.The test shows that the removal of Pb^(2+)+and Cd^(2+)+by VNF-4040K and ESNA1-4040 nanofiltration membranes are affected by the operating conditions,and the change of influent concentration has a great impact on the removal rate,reaching the highest when the concentration multiple is 1,which are 94.76%,84.49%,97.64%and 95.69%respectively;the membrane flux positively is correlated with the retention of heavy metal ions(Pb^(2+),Cd^(2+))by the two nanofiltration membranes;the conductivity and recovery rates are negatively correlated with the removal rate.Alkaline conditions are conducive to the removal of heavy metal ions(Pb^(2+),Cd^(2+))by nanofiltration membrane;ESNA1-4040 membrane has better removal efficiency of Pb^(2+)and Cd^(2+)than VNF-4040 K membrane.