Thermo-responsive PVDF-grafted-PVNCL membrane with switchable wettability for efficient oil-water separation

Industrial activities in the oil and gas, petrochemical, pharmaceutical, and food and beverage sectors are significant contributors to oily wastewater generation. This environmental concern poses serious threats to drinking water quality, groundwater reservoirs, aquatic ecosystems, and human health [1]. To address these challenges, membrane technology has emerged as an efficient and environmentally friendly solution for oil-water separation, offering high efficiency and exceptional capacity. This study focuses on developing a thermo-responsive membrane through alkali pretreatment and UV-induced surface modification of commercial polyvinylidene fluoride (PVDF) membranes. Alkali pretreatment using sodium hydroxide (NaOH) solution introduces hydroxyl groups onto the PVDF membrane surface. Subsequently, surface modification with 3-methacryloxypropyltrimethoxysilane (MPTS) enhances adhesion for the polymerization step. Poly(N-vinyl caprolactam) (PNVCL) is then successfully grafted onto the PVDF surface via a UV-induced surface modification method, using alpha-detoglutaric acid (KGA) as a photo-initiator. The modified membranes were thoroughly characterized by FT-IR, XPS, SEM, and water contact angle measurement. The membrane performance tests have shown that the surface membrane modification by PVNCL enhances hydrophilicity while imparting thermo-responsive properties, thus enabling highly efficient oil-water separation[2].