Development of Janus PSF / PVA Membranes for Efficient Desalination via Membrane Distillation

ABSTRACT A Janus membrane was developed to enhance flux in the membrane distillation (MD) process for desalination. The membrane was fabricated by coating a thin hydrophilic crosslinked polyvinyl alcohol (PVA) layer onto a hydrophobic polysulfone (PSF) membrane. Surface characterization by FESEM and AFM demonstrated a consistent PVA coating and a decrease in membrane surface roughness. Water contact angle decreased significantly from 94° to 64°, indicating enhanced surface hydrophilicity. Furthermore, liquid entry pressure (LEP w ) revealed an increase from 6.5 to 7.0 bar after PVA modification, confirming the improved resistance to liquid intrusion. To assess its separation efficiency, the membrane was evaluated using a direct contact membrane distillation (DCMD) setup with a 3.5 wt.% NaCl saline feed. Results showed a notable increase in vapor flux from 17.13 kg/m 2 h for the PSF membrane to 26.33 kg/m 2 h for the PSF/PVA membrane. In addition, the Janus membrane demonstrated excellent long‐term stability over a 15‐h continuous operation, maintaining steady flux without delamination or performance degradation. These findings highlight the effectiveness of the PSF/PVA membrane structure in enhancing water vapor transport, offering a novel strategy to improve flux and performance in MD applications.