新型正向渗透分离膜的制备及可回收聚电解质汲取液的研制

近年来，正向渗透过程作为未来的清洁水生产技术因其独特的常压操作、高截留率和低膜污染倾向等特性受到越来越多的关注。然而目前有一些技术难题，如膜通量偏低、溶质泄漏、浓差极化严重、汲取液回收难度大等，还制约着正向渗透在废水处理和海水淡化中的实际应用。要取得FO过程的突破和工业化，研发合适的FO膜和汲取液溶质仍然是其面临的重要挑战。我们拟采用的新型制模技术包括:1）在界面聚合反应的单体中引入环糊精、杯芳烃或聚倍半硅氧烷等，对致密层进行分子设计以制备薄膜复合膜；2）对层层自组装沉积的单层聚电解质膜进行交联改性，以同时提高其截盐率和膜通量。同时，我们也合成研制一系列不同分子量不同阴阳离子的有机酸盐聚电解质，作为新型汲取液溶质并通过超滤或纳滤方法在渗透过程后完全回收，以解决正向渗透过程中的泄漏问题和回收的高能耗问题。通过上述研究，我们希望可以为正向渗透膜技术的实际应用做出积极的贡献。

In recent years, forward osmosis (FO), as a novel membrane separation technique for clean water production, gains more and more attention in both academia and industry because of its atmospheric operation, high salt rejection, low tendency of membrane fouling, and etc. However, some technical problems existing in FO technology, such as low membrane flux, solute leakage, severe concentration polarization, and the difficulty of draw solution recovery, still restrict the real applications of FO technology in wastewater treatment and desalination industry. Developing suitable FO　membranes and draw solutes are still the important chanllenges in order to achieve the breakthoughs and industrilization of the FO　processes. In this research project, we will focus on these technical difficulties to carry out our research work in order to achieve high-performance forward osmosis processes. Several novel membrane fabrication techniques will be employed, including: 1) introduction of cyclodextrin, calixarene, polyhedral oligomeric silsesquioxane, etc into the monomers for interfacial polymerization in order to molecularly design the selective layer of the thin film composite membrane; (2) cross-linking modification of the one-layer polyelectrolyte membrane fabricated by layer-by-layer deposition, in order to improve its salt rejection and water flux simultaneously. In this research project, we will also develop various polyelectrolyte salts including acrylic acid salts, sulfonate salts and methyl acrylate acrylic acid salts, as draw solutes for applications in forward osmosis. They could be recovered by ultrafiltration or nanofiltration and used for next forward osmosis test. By employing those novel draw solutes, it is effective to avoid the leakage of the draw solute as well as the high energy consumption during draw solute recycling. It is highly expected that through the investigation of appropriate FO membranes and the molecular design of draw solutes, the research work in this project would make valuable contributions to the final industrialization of the FO process.