Engineering hydrophobic surface on polyethersulfone membrane with bio‐inspired coating for desalination with direct contact membrane distillation

Abstract

AbstractA novel polyethersulfone (PES) membrane was prepared for desalination and treating saline feed solution containing humic acid in membrane distillation. PES has been selected to fabricate specialized membranes for direct contact membrane distillation, and membrane structure and characteristics have been controlled by dope solution composition and exposure time to water vapor during the phase inversion step. Since PES membranes are vulnerable to wetting, surface modification for hydrophobicity has been applied by a novel method inspired by lotus. This method uses a layer‐by‐layer surface modification of polydopamine, silver nanoparticles, and 1‐dodecanethiol to create adhesion, hierarchical roughness, and hydrophobicity. In dopamine polymerization, an oxidant has been added to improve the quality and speed of the process. Membranes were successfully fabricated and modified; the best‐case membrane with 30% triethylene glycol content and 30 s exposure time to water vapor showed outstanding results with 12.57 kg/h.m2 mass flux and 99.7% salt rejection in desalination also showed good results in treating saline feed containing humic acid with 10.02 kg/h.m2 flux and 99.71% rejection. The fabricated hydrophobic membrane's long‐term results showed promising and stable performance for commercial applications.