Excellent wetting resistance and anti-fouling performance of PVDF membrane modified with superhydrophobic papillae-like surfaces

Abstract

With hydrophobicity as a basic requirement for membrane used in membrane distillation (MD) process, the membrane wetting and fouling can be effectively alleviated with superhydrophobic surface. Since the applications of existing methods were usually restricted by certain limitations, it is highly essential to develop a facile and effective approach to fabricate a superhydrophobic surface for MD process. In this study, a one-step method was employed for superhydrophobic coating with papillae-like structure on polyvinylidene fluoride (PVDF) membrane surface. The variations in surface morphology and water contact angle (WCA) were explicated as functions of PVDF and polybasic alcohol mixture (PG) contents in coating solution, the immersion temperature and time. The optimal modification was conducted in a 45°C coating solution for 35s with 2wt% of PVDF and 30wt% of PG, resulting in a superhydrophobic surface with a maximum WCA of 156.8°. Moreover, the performance of the modified membrane was compared with the original membrane in MD process with different feeds. The modified membrane demonstrated the excellent wetting and fouling resistance after superhydrophobic modification. Through the efficient one-step fabrication for superhydrophobic papillae-like surfaces, this study proposed a promising strategy to improve the performance of PVDF membrane in the MD process.