Ray Saikat Sinha, Chen Shiao-Shing, Chang Hau-Ming, Dan Thanh Cao Ngoc, Quang Le Huy, Nguyen Nguyen Cong
Institute of Environmental Engineering and Management, National Taipei University of Technology No. 1, Sec. 3, Zhongxiao E. Rd Taipei-10608 Taiwan
Faculty of Environment and Natural Resources, Dalat University Vietnam.
RSC Adv. 2018 Mar 6;8(18):9640-9650. doi: 10.1039/c8ra01043a. eCollection 2018 Mar 5.
Superhydrophobic membranes are essential for improved seawater desalination. This study presents the successful casting of a three-layered membrane composed of a top superhydrophobic coating onto a polypropylene (PP) mat through simple sol-gel processing of octadecyltrimethoxysilane (OTMS), and the bottom layer was casted with hydrophilic poly(vinyl alcohol) (PVA) by using a knife casting technique; this membrane represents a novel class of improved-performance membranes consisting of a top superhydrophobic coating onto a hydrophobic PP mat and a hydrophilic layer (PVA) at the bottom. OTMSs are well known low-surface-energy materials that enhance superhydrophobicity, and they were observed to be the ideal chemical group for increasing the hydrophobicity of the PP mat. The PVA layer acted as base layer absorbing the condensed vapor and thus enhancing the vapor flux across the membrane. The hybrid three-layered membrane exhibited superhydrophobicity, with an average contact angle of more than 160°, and demonstrated high performance in terms of rejection and water flux. This study also examined the pore size distribution, surface roughness, surface area, tensile strength, water flux, and salt rejection of the fabricated membrane. The salt rejection level was calculated to be 99.7%, and a high permeate flux of approximately 6.7 LMH was maintained for 16 h.
超疏水膜对于改进海水淡化至关重要。本研究通过对十八烷基三甲氧基硅烷（OTMS）进行简单的溶胶-凝胶处理，成功地在聚丙烯（PP）垫上浇铸了一种由顶部超疏水涂层组成的三层膜，底层通过刮涂技术浇铸了亲水性聚乙烯醇（PVA）；这种膜代表了一类新型的高性能膜，由疏水PP垫上的顶部超疏水涂层和底部的亲水性层（PVA）组成。OTMS是众所周知的低表面能材料，可增强超疏水性，并且观察到它们是增加PP垫疏水性的理想化学基团。PVA层作为吸收冷凝蒸汽的基层，从而提高了跨膜蒸汽通量。这种混合三层膜表现出超疏水性，平均接触角超过160°，并且在截留率和水通量方面表现出高性能。本研究还考察了所制备膜的孔径分布、表面粗糙度、表面积、拉伸强度、水通量和盐截留率。计算得出盐截留率为99.7%，并在16小时内保持约6.7 LMH的高通量渗透通量。
