Modification of PVDF Hollow Fiber Membranes by SMM Coating for Pharmaceutical Wastewater Treatment through a Liquid-Liquid Membrane Contactor System

Given the potential environmental and health hazards posed by pharmaceutical wastewater, effective treatment methods are crucial. A liquid-liquid membrane contactor is an innovative separation technology applied in wastewater treatment. This study involved the fabrication and modification of highly porous polyvinylidene fluoride (PVDF) hollow fiber membranes with a surface-modifying macromolecule (SMM) coating for the extraction of penicillin-G from wastewater using a liquid-liquid membrane contactor system. FESEM analysis demonstrated a thin outer layer characterized by a finger-like structure, along with a thick sub-layer exhibiting sponge-like properties in the membrane. The decrease in inner surface porosity and pore size indicated the development of a thin SMM-coated layer. The modified membrane displayed an overall porosity of around 80%. The water contact angle on the inner surface increased from approximately 87° to 108° after SMM coating, indicating improved surface hydrophobicity. Additionally, the liquid entry pressure of the modified PVDF membrane rose from 450 to 550 kPa. The modified membrane featured an average pore size of 0.22 µm and an effective surface porosity of 2180 m-1, signifying considerable permeability. Over 30 hours of operation in the membrane contactor, the modified membrane maintained a consistent penicillin-G extraction flux of 1.18×10-3 kg/m2 s, while the unmodified PVDF membrane experienced a 32% decrease in flux. Thus, the enhanced PVDF hollow fiber membrane, with its improved surface hydrophobicity and permeability, shows great potential for wastewater treatment utilizing a liquid-liquid membrane contactor process.