Lin Yi-Li, Chiang Pen-Chi, Chang E-E
Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei, Taiwan.
J Hazard Mater. 2007 Jul 19;146(1-2):20-9. doi: 10.1016/j.jhazmat.2006.11.050. Epub 2006 Nov 30.
The removal of small trihalomethane precursors (THMPs) from aqueous solution by two commercial nanofiltration membranes (NF70 and NF270) was investigated. Resorcinol, phloroglucinol, and 3-hydroxybenzoic acid were selected as model compounds of small THMPs, while tannic acid was chosen as a medium molecular disinfection by-product (DBP) precursor for comparison. The performance of nanofiltration membranes were evaluated by introducing polyethylene glycol (PEG) solutions and uncharged saccharides to estimate molecular weight cut-off (MWCO) and membrane pore radii, respectively. The streaming potential was measured to estimate the membrane surface charge at different pH values, which reveals that the NF270 membrane is more pH-sensitive than the NF70 membrane. The rejections of the above selected THMPs were assessed under various pH values, and the removal efficiencies of THMPs for both membranes at high pH values are reasonably well. Charge exclusion is the prevailing mechanism for the selected small model compounds retended by the negatively charged nanofiltration membranes, while size exclusion and adsorption are controlled mechanisms but not sufficient for the rejection of unionized small organic molecules. In general, the NF270 membrane exhibits the superior permeation rate value, which takes an advantage over the NF70 membrane from the aspect of energy conservation.
研究了两种商用纳滤膜（NF70和NF270）从水溶液中去除小三卤甲烷前体（THMPs）的性能。选择间苯二酚、间苯三酚和3-羟基苯甲酸作为小THMPs的模型化合物，同时选择单宁酸作为中分子消毒副产物（DBP）前体进行比较。通过引入聚乙二醇（PEG）溶液和不带电荷的糖类分别评估纳滤膜的截留分子量（MWCO）和膜孔半径，从而对纳滤膜的性能进行评价。测量流动电位以估计不同pH值下的膜表面电荷，结果表明NF270膜比NF70膜对pH更敏感。在不同pH值下评估上述所选THMPs的截留率，两种膜在高pH值下对THMPs的去除效率都相当不错。电荷排斥是带负电的纳滤膜截留所选小模型化合物的主要机制，而尺寸排斥和吸附是控制机制，但不足以截留未电离的小有机分子。总体而言，NF270膜表现出更高的渗透速率值，从节能方面优于NF70膜。
