School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
Water Res. 2013 Jul 1;47(11):3773-81. doi: 10.1016/j.watres.2013.04.034. Epub 2013 Apr 27.
We report a study to explore new materials and a new concept for temperature driven quasi-continuous desalination using hydrogels as draw agents in forward osmosis (FO). This concept is enabled by the design and preparation of thermally responsive hydrogels having a semi-interpenetrating network (semi-IPN) structure. Thermally responsive semi-IPN hydrogels were synthesized by polymerization of N-isopropylacrylamide (NIPAm) in the presence of polysodium acrylate (PSA) or polyvinyl alcohol (PVA). Their functions as draw agents in FO were systematically studied and compared with hydrogels prepared from the PNIPAm homopolymer or the NIPAM-SA copolymer. While the semi-IPN hydrogels displayed the desirable balanced thermally responsive swelling and dewatering behavior, the NIPAm-SA copolymer hydrogels were found to have poor dewatering behavior, making them unsuitable for a continuous temperature driven desalination process. At 40 °C, the semi-IPN hydrogels rapidly release nearly 100% of the water absorbed during the FO drawing process carried out at room temperature. Results clearly indicate the potential of semi-IPN hydrogels as semi-solid draw agents in the FO process, in which quasi-continuous desalination could be achieved by cyclic heating and cooling within a moderate temperature change.
我们报告了一项研究，旨在探索使用水凝胶作为正向渗透（FO）中的汲取剂，实现温度驱动的准连续脱盐的新材料和新概念。这一概念是通过设计和制备具有半互穿网络（semi-IPN）结构的热响应水凝胶来实现的。热响应半互穿网络水凝胶是通过在存在聚丙烯酸钠（PSA）或聚乙烯醇（PVA）的情况下聚合 N-异丙基丙烯酰胺（NIPAm）而合成的。系统研究了它们作为 FO 中汲取剂的功能，并将其与由 PNIPAm 均聚物或 NIPAm-SA 共聚物制备的水凝胶进行了比较。半互穿网络水凝胶表现出理想的平衡热响应溶胀和脱水行为，而 NIPAm-SA 共聚物水凝胶被发现具有较差的脱水行为，使其不适合连续的温度驱动脱盐过程。在 40°C 下，半互穿网络水凝胶在室温下进行的 FO 汲取过程中迅速释放近 100%吸收的水。结果清楚地表明，半互穿网络水凝胶作为 FO 过程中的半固态汲取剂具有潜力，通过在适度的温度变化内进行循环加热和冷却，可以实现准连续脱盐。
