Visible-light photocatalytic membranes based on heterostructured Fe3O4-doped g-C3N4/TiO2 catalysts

BACKGROUND Desalination membranes have been widely in demand for separating dyes and salts. However, dyes are easily adsorbed on/in the membranes, deteriorating membrane performance. Coupling photocatalysis and membrane separation might be a promising strategy for efficiently alleviating membrane fouling. Aiming at the defects of single catalyst, this work constructed photocatalytic membranes based on heterostructured Fe 3 O 4 -doped g-C 3 N 4 (FeCN)/TiO 2 catalysts by successively filtrating FeCN aqueous dispersion and titanium butoxide/isopropanol solution on the hydrolyzed polyacrylonitrile substrate. RESULTS The H-bonds among TiO 2 , FeCN and substrate lead to excellent load stability of the photoresponsive layer. Due to the low-potential conduction band and high conductivity of Fe 3 O 4 and the low-potential conduction band of TiO 2 in FeCN/TiO 2 , electrons can be more easily transferred to guarantee the high separation efficiency of electrons and holes. Hence the membrane not only exhibited superior permeability (104 L m −2 h −1 bar −1 ) and dye desalting performance (Coomassie brilliant blue R250 rejection of >98.80% and NaCl rejection of <7.00%), but also displayed highly efficient and stable dye photodegradation. CONCLUSION The degradation efficiency surpassed that reported in the literature in comparable circumstances, and the recovery rate of permeability still reached 89.12% after three fouling–photodegradation cycles. This work provides new opportunities for designing high-efficiency self-cleaning membranes to solve membrane fouling based on low-cost materials. © 2023 Society of Chemical Industry (SCI).