Removal of antibiotics from black water by a membrane filtration-visible light photocatalytic system
Hongbo Liu, Haodong Zhang, Xinyi Dong, Chengyang Wu, Éric Lichtfouse
Abstract
To address the problem of pollution caused by antibiotics in black water, we synthesized membranes containing the g-C 3 N 4 /TiO 2 photocatalysts and tested them for the removal of sulfamethoxazole (SMZ) and tetracycline (TC) in pure water conditions and black water. We compared the basic membrane filtration and photocatalytic performance of the g-C 3 N 4 /TiO 2 and the PVDF membranes, and investigated the influencing factors and application aspects of membrane filtration-photocatalytic systems for antibiotic removal. The anti-fouling performance and re-usability of g-C 3 N 4 /TiO 2 membranes were investigated by evaluating the fouling reversibility of photocatalytic membranes. The results showed that g-C 3 N 4 /TiO 2 improved the porosity, hydrophilicity and permeability of the membranes significantly. PgT-3 (PVDF/g-C 3 N 4 /TiO 2 ) membrane with 0.03 wt% of g-C 3 N 4 /TiO 2 has the best overall performance with 72.8 % and 63.9 % removal efficiency for SMZ and TC respectively. Neutral or weakly acidic solution (pH = 5.0–7.0) is favorable for the removal of both study antibiotics. The complex composition of black water increased the adsorption load on the membrane and caused the inhibition of the photocatalysis of the g-C 3 N 4 /TiO 2 membrane. The absorption of visible light by g-C 3 N 4 accelerates the electron transfer rate and promotes the separation of electrons from holes. The oxidation-active substance h + produced in the system plays an important role in the removal of SMZ and TC.