Superhydrophobic PA membrane for robust anti-wetting membrane distillation to water reclamation from textile wastewater

Abstract

Membrane Distillation is an up-and-coming technology for water recovery from textile wastewater, mainly due to the possibility of using waste heat from residual flows of the dyeing process. However, the membrane wetting propensity against low surface tension solutes is a drawback to be overcome to enable the MD operation against this complex effluent. Herein, we physically modified a cheap and widely available PA membrane via one-step electrospraying to improve the anti-wetting properties against detergent and a reactive black dye solution. The polymer blend contained polydimethylsiloxane, polyvinylidene, and silica nanoparticles. An in-depth morphological, thermal and chemical evaluation was performed. The resulting superhydrophobic membrane reached a contact angle of 167.13 ± 22.29° against water and 160.5 ± 2.6° against a detergent solution. Adding a modified layer did not compromise the membrane porosity or pore size despite the increased membrane thickness. DCMD operation revealed an antifouling property of modified membrane against reactive black solution and an improved rejection rate against detergent solution compared to the pristine PA membrane, which wetted in detergent operation. The proposed modification consisted of a simple and quick way to enable MD in water reclamation from textile wastewater, overcoming the biggest concerns related to surfactant's presence.