Ke Xiao-Xue, Wang Ting-Yu, Wu Xiao-Qiong, Chen Jiang-Ping, Zhao Quan-Bao, Zheng Yu-Ming
CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China.
University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
Membranes (Basel). 2021 Mar 27;11(4):237. doi: 10.3390/membranes11040237.
Electrospun nanofiber with interconnected porous structure has been studied as a promising support layer of polyamide (PA) thin-film composite (TFC) forward osmosis (FO) membrane. However, its rough surface with irregular pores is prone to the formation of a defective PA active layer after interfacial polymerization, which shows high reverse salt leakage in FO desalination. Heat-curing is beneficial for crosslinking and stabilization of the PA layer. In this work, a nanofiber-supported PA TFC membrane was conceived to be cured on a hot water surface with preserved phase interface for potential "defect repair", which could be realized by supplementary interfacial polymerization of residual monomers during heat-curing. The resultant hot-water-curing FO membrane with a more uniform superhydrophilic and highly crosslinked PA layer exhibited much lower reverse salt flux (FO: 0.3 gMH, PRO: 0.8 gMH) than that of oven-curing FO membrane (FO: 2.3 gMH, PRO: 2.2 gMH) and achieved ∼4 times higher separation efficiency. It showed superior stability owing to mitigated reverse salt leakage and osmotic pressure loss, with its water flux decline lower than a quarter that of the oven-curing membrane. This study could provide new insight into the fine-tuning of nanofiber-supported TFC FO membrane for high-quality desalination via a proper selection of heat-curing methods.
具有相互连接的多孔结构的电纺纳米纤维已被研究作为聚酰胺(PA)薄膜复合(TFC)正渗透(FO)膜的一种有前景的支撑层。然而,其具有不规则孔隙的粗糙表面在界面聚合后容易形成有缺陷的PA活性层,这在FO脱盐中表现出高的反向盐泄漏。热固化有利于PA层的交联和稳定。在这项工作中,构思了一种纳米纤维支撑的PA TFC膜在具有保留相界面的热水表面上进行固化以实现潜在的“缺陷修复”,这可以通过热固化过程中残留单体的补充界面聚合来实现。所得的具有更均匀的超亲水和高度交联PA层的热水固化FO膜表现出比烘箱固化FO膜(FO:2.3 gMH,PRO:0.8 gMH)低得多的反向盐通量(FO:0.3 gMH,PRO:0.8 gMH),并且实现了约4倍的更高分离效率。由于反向盐泄漏和渗透压损失减轻,它表现出优异的稳定性,其水通量下降低于烘箱固化膜的四分之一。这项研究可以通过适当选择热固化方法为纳米纤维支撑的TFC FO膜的精细调节以实现高质量脱盐提供新的见解。