Sustainable water desalination with anti-wetting Janus membranes under simulated industrial low-grade fluctuated heat conditions in DCMD

Abstract

Membrane distillation (MD) is a promising technology for desalination and wastewater treatment, but its widespread application is hindered by membrane wetting, particularly when treating hypersaline water with surfactants. This study investigates the performance of Janus polyamide-polyvinylidene fluoride (PA/PVDF) membranes, which are synthesized using reverse interfacial polymerization (RIP) to form a hydrophilic polyamide (PA) layer on a hydrophobic PVDF substrate, combining hydrophilic and hydrophobic properties to address wetting issues in MD. We examined the membrane’s performance under varying feed temperatures (40–60 ℃), mimicking industrial low-grade heat conditions, and in highly saline solutions containing 0.6 M NaCl and 0.4 mM sodium dodecyl sulfate (SDS). The Janus PA/PVDF membrane demonstrated excellent flux stability (up to 27 LMH at 60 ℃) and high salt rejection even under continuous 8-hour operation. Notably, despite the presence of surfactants, the membrane maintained its anti-wetting performance by effectively preventing pore wetting, attributed to the hydrophilic PA layer that retained the SDS molecules and minimized liquid infiltration. These findings highlight the significant advantages of Janus membranes in mitigating temperature-dependent wetting, making them a promising solution for energy-efficient desalination and wastewater reclamation in real-world applications, where fluctuating temperatures and complex feed conditions are common.