Janus hollow fibre membranes with intrusion anchored structure for robust desalination and leachate treatment in direct contact membrane distillation

Abstract

High-performance Janus membranes have been intriguing for membrane distillation due to its distinctive features for improving fouling and wetting resistance. However, long-term structural stability remains challenging owing to delamination caused by the opposite affinity between the two different kinds of materials. Herein, a physically-anchored hydrophilic layer containing graphene oxide (GO)/poly(vinyl alcohol) (PVA)/sulfosuccinic acid (SSA) i.e., GOSP layer was formed on the surface of a microporous polypropylene (PP) hollow fibre membrane. Meanwhile, the nanostructure of the GOSP layer could be tuned from 2-dimensional lamellar to 3-dimensional mixed matrix, exhibiting various water transport properties. As a result, the fabricated Janus membrane with the partially intruded pore channels exhibited superior antiwetting and antifouling performance for desalination and wastewater treatment in the direct contact membrane distillation process. For surfactant containing saline water, the GOSP/PP Janus membrane with optimised PVA/GO ratio possessed noticeably enhanced anti-wetting property compared to pristine PP membrane. In particular for leachate treatment, the GOSP/PP membrane produced high quality permeate with <1 mg/L ions and 10 mg/L total organics and maintained stable water flux while the leachate was concentrated by 5 times (80 % water recovery), providing great potential for using membrane distillation towards zero liquid discharge.