Salt cleaning of organic-fouled reverse osmosis membranes
Salt cleaning of organic-fouled reverse osmosis membranes
复制标题
DOI：
10.1016/j.watres.2006.11.043
复制
发表时间：
2007-03-01
期刊：
影响因子：
12.8
通讯作者：
Elimelech, Menachem
中科院分区：
文献类型：
--
作者：
Lee, Sangyoup;Elimelech, Menachem
研究了用浓盐水清洗有机污染反渗透膜的方法。以藻酸盐和果胶等多糖和Suwannee河天然有机物为模型有机污染物。通过系统地改变影响盐清洗效率的化学和物理因素，我们能够阐明盐清洗过程中涉及的过程和机制。研究的化学因素包括盐剂量、盐类型和有机污垢成分，而物理因素包括清洁接触时间、错流速度、清洁溶液温度和渗透速率。原子力显微镜（AFM）被用来量化盐清洗时分子间污垢-污垢粘附的减少。我们的研究结果表明，盐清洗是相当有效的清洗反渗透膜的凝胶形成亲水性有机污垢，如海藻酸盐和果胶。所提出的盐清洁机制涉及膜表面上的交联凝胶层在暴露于盐溶液后的结构变化，随后是离子交换反应，其诱导钙-污垢键的断裂以及污垢分子之间的钙桥接（交联）。从AFM力测量以及污垢释放实验获得的结果证实，这些化学反应是盐清洗的主要机制。盐清洗似乎是一种有效的清洗方法，并可能证明是有用的膜为基础的先进的废水回收，其中大部分的有机污垢是亲水性的。(C)2006爱思唯尔有限公司保留所有权利。
Cleaning of organic-fouled reverse osmosis membranes with concentrated salt solutions has been investigated. Polysaccharides (alginate and pectin) and Suwannee River natural organic matter were used as model organic foulants. By systematically varying the chemical and physical factors affecting salt cleaning efficiency, we were able to elucidate the processes and mechanisms involved during salt cleaning. Chemical factors investigated included salt dose, salt type, and organic foulant composition, while physical factors included cleaning contact time, crossflow velocity, cleaning solution temperature, and permeation rate. Atomic force microscopy (AFM) was utilized to quantify the reduction in intermolecular foulant-foulant adhesion upon salt cleaning. Our results showed that salt cleaning was quite effective in cleaning reverse osmosis membranes fouled by gel-forming hydrophilic organic foulants, such as alginate and pectin. The proposed mechanism for salt cleaning involves structural changes of the cross-linked gel layer on the membrane surface upon exposure to the salt solution followed by an ion exchange reaction that induces the breakup of calcium-foulant bonds as well as calcium bridging (cross-linking) between foulant molecules. The results obtained from AFM force measurements as well as foulant release experiments confirmed that these chemical reactions were the major mechanisms of salt cleaning. Salt cleaning appears to be an effective cleaning method, and may prove useful for membrane-based advanced wastewater reclamation, where a large fraction of the organic foulants is hydrophilic. (C) 2006 Elsevier Ltd. All rights reserved.