The role of membrane surface charge and solute physico-chemical properties in the rejection of organic acids by NF membranes
The role of membrane surface charge and solute physico-chemical properties in the rejection of organic acids by NF membranes
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DOI：
10.1016/j.memsci.2004.09.041
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发表时间：
2005-03-01
影响因子：
9.5
通讯作者：
Drewes, JE
中科院分区：
文献类型：
--
作者：
Bellona, C;Drewes, JE
本研究的目的是探讨静电相互作用的纳滤膜的选择有机酸的排斥的贡献。在不同的pH值和给水化学条件下，研究了两种商业纳滤膜的有效膜表面电荷（通过两种方法测定的zeta电位测量）。本研究选择了六种不同的有机酸，代表了新兴有机痕量污染物的典型物理化学性质。本研究的结果表明，带负电荷的有机酸的截留率大于基于空间排阻的预期，并且主要由膜的表面电荷驱动，并且与溶质的电离度相关。增加给水pH值导致表面负电荷增加，去质子化状态的溶质百分比增加，通过静电排斥的排斥增加。药物残留物布洛芬（一种具有疏水特性的有机酸）的截留率也依赖于pH值，但在pH值低于pK（a）时，布洛芬被吸附并通过膜分配。在pH高于pK（a）时，由于溶解度增加和静电排斥的主导作用，布洛芬的吸附最小。在给水中的钙的存在下，降低了有效的mernbrane表面电荷（由电泳迁移率测量确定）的两种膜测试，然而，带负电荷的有机溶质的排斥率下降，只有膜的截留分子量大于溶质的分子量。(C)2004 Elsevier B.V.保留所有权利。
The objective of this study was to investigate the contribution of electrostatic interactions to the rejection of selected organic acids by nanofiltration membranes. Effective membrane surface charge (determined by two methods of zeta potential measurements) of two commercial nanofiltration membranes was examined at different pH values and feed water chemistries. Six different organic acids were selected for this study representing typical physico-chemical properties of emerging organic trace pollutants. Findings of this study indicated that the rejection of negatively charged organic acids was larger than expected based on steric exclusion and was primarily driven by the surface charge of the membrane and correlated with the degree of ionization of the solute. Increasing feed water pH resulted in an increased negative surface charge, an increased percentage of solutes in the deprotonated state and an increased rejection through electrostatic repulsion. The rejection of the pharmaceutical residue ibuprofen, an organic acid with hydrophobic properties, was also pH dependent, but at pH values below the pK(a) ibuprofen adsorbed and partitioned through the membrane. At pH above the pK(a), adsorption of ibuprofen was minimal due to an increased solubility and the dominant role of electrostatic repulsion. The presence of calcium in the feed water lowered the effective mernbrane surface charge (as determined by electrophoretic mobility measurements) of both membranes tested, however, rejection of negatively charged organic solutes decreased only for membranes with a molecular weight cut-off larger than the solute molecular weight. (C) 2004 Elsevier B.V. All rights reserved.