Modification of polyamide reverse osmosis membranes seeking for better resistance to oxidizing agents
Modification of polyamide reverse osmosis membranes seeking for better resistance to oxidizing agents
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DOI：
10.12989/mwt.2012.3.3.169
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发表时间：
2012-07
期刊：
影响因子：
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通讯作者：
Lucinda F. Silva;R. C. Michel;C. P. Borges
中科院分区：
文献类型：
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作者：
Lucinda F. Silva;R. C. Michel;C. P. Borges
使用商业芳香族聚酰胺薄膜复合材料 (TFC) 反渗透 (RO) 膜的主要限制之一是在长期运行中保持高性能，因为聚酰胺 (PA) 皮层对氧化剂（例如氯）敏感，即使在给水中浓度非常低的情况下也是如此。本文报道了商业 TFC RO 膜 (BW30-Dow Filmtec) 的表面改性，方法是用戊二醛 (GA) 交联的聚乙烯醇 (PVA) 薄膜覆盖该膜，以提高其耐氯性。使用不同GA/PVA质量比（即0.0022、0.0043和0.013）的PVA 1.0 wt.%溶液在25℃和40℃下进行交联反应。水溶胀测量表明在 40°C 和 GA/PVA 0.0043 下制备的 PVA 薄膜的最大交联密度。 ATR-FTIR 和 TGA 分析证实了 GA 和 PVA 之间的反应。使用原始膜和改性膜的 SEM 图像来评估表面涂层。通过将原始膜和改性膜暴露于氧化剂溶液（NaClO 300 mg/L、NaCl 2,000 mg/L、pH 9.5）中并测量超过 100 小时的透水性和脱盐率来评估原始膜和改性膜的耐氯性。通过将 PA 商业膜的耐氯性从 1,000 ppm.h 提高到 15.000 ppm.h 以上，有效地证明了表面改性。
One of the major limitations in the use of commercial aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes is to maintain high performance over a long period of operation, due to the sensitivity of polyamide (PA) skin layer to oxidizing agents, such as chlorine, even at very low concentrations in feed water. This article reports surface modification of a commercial TFC RO membrane (BW30-Dow Filmtec) by covering it with a thin film of poly(vinyl alcohol) (PVA) crosslinked with glutaraldehyde (GA) to improve its resistance to chlorine. Crosslinking reaction was carried out at 25 and 40oC by using PVA 1.0 wt.% solutions at different GA/PVA mass ratio, namely 0.0022, 0.0043 and 0.013. Water swelling measurements indicated a maximum crosslinking density for PVA films prepared at 40oC and GA/PVA 0.0043. ATR-FTIR and TGA analysis confirmed the reaction between GA and PVA. SEM images of the original and modified membranes were used to evaluate the surface coating. Chlorine resistance of original and modified membranes was evaluated by exposing it to an oxidant solution (NaClO 300 mg/L, NaCl 2,000 mg/L, pH 9.5) and measuring water permeability and salt rejection during more than 100 h period. The surface modification effectively was demonstrated by increasing the chlorine resistance of PA commercial membrane from 1,000 ppm.h to more than 15.000 ppm.h.