Superhydrophobic PVDF/TiO₂-SiO₂ Membrane with Hierarchical Roughness in Membrane Distillation for Water Recovery from Phenolic Rich Solution Containing Surfactant

Superhydrophobic poly(vinylidene fluoride) (PVDF) membrane incorporated with nanoparticles was applied in membrane distillation to recover water from phenolic rich solution containing surfactant. The membranes coated on woven support were fabricated using phase inversion with dual bath coagulation and post-modified using silane. The membranes incorporated with TiO₂, SiO₂, or a mixture of TiO₂-SiO₂ nanoparticles achieved the water contact angle higher than 160°. The addition of TiO₂-SiO₂ mixture into PVDF matrix further enhanced the hierarchical roughness of membrane. Hence, PVDF/TiO₂-SiO₂ membrane achieved the highest permeation flux and rejected 99.9% of gallic acid in the feed (100 g/L). PVDF/TiO₂-SiO₂ membrane also maintained a relative flux (J/J0) higher than 0.9 after 8 h of operation. Even with the presence of surfactant in phenolic rich solution, PVDF/TiO₂-SiO₂ membrane was able to exhibit relative flux above 0.8. The significant changes on the hydrophobicity and chemical properties of PVDF/TiO₂-SiO₂ membrane due to fouling were not observed after 50 h of static adsorption test.