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 (LEPw) 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/m²h for the PSF membrane to 26.33 kg/m²h for the PSF/PVA membrane. In addition, the Janus membrane demonstrated excellent long-term stability over a 15-hour 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.

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