Anti-Wetting PVDF Membrane Modification by Coating Fluoride and Deposing Different Silicon Contents for Membrane Distillation Treatment of Ammonia Nitrogen Wastewater

Membrane distillation (MD) was a promising approach for treating highly concentrated ammonia–nitrogen wastewater. However, membrane wetting often limited large-scale application. To address this, we built an anti-wetting layer on a commercial PVDF membrane surface by coating fluoride and depositing SiO2 nanoparticles. Three PVDF/ SiO2/F membranes were prepared with different silicon contents: 1%, 6%, and 12% (volume) of tetraethyl orthosilicate (TEOS). These processes created different surface roughness on the modified membranes. Results showed that the membrane containing 6% TEOS exhibited the best resistance to sodium dodecyl sulfate (SDS) in NaCl solution. This optimized membrane was subsequently tested with real wastewater, including source-separated urine and landfill leachate. In 10 h, it removed 97.5% of total organic carbon (TOC) from urine, achieving an ammonia absorption rate of 55.1% and removed 92.4% from leachate, with an ammonia absorption rate of 37.58%. These results provide a reference for membrane fabrication parameter optimization to enhance the membrane’s anti-wetting ability.