Abatement of sulfadiazine in water under a modified ultrafiltration membrane (PVDF-PVP-TiO2-dopamine) filtration-photocatalysis system

Abstract

The technique of coupling photocatalysis and membrane filtration was applied to the abatement of sulfonamide antibiotics in water. TiO2 photocatalyst has been aroused widespread concern in recent years due to its low price and easy availability. A PVDF-PVP-TiO2-Dopamine blend ultrafiltration membrane (PPTD) was first fabricated in this study and removal of sulfadiazine (SD) in water using a PPTD membrane filtration-photocatalysis system was realized. The addition of PVP-TiO2-Dopamine increased the porosity and average pore size of membranes, resulting in improved hydrophilicity, flux of modified membranes. In pure water, the SD removal efficiency was 91.4% with a first-order rate constant k 0.0216 min−1 under the optimum conditions ([SD]0 = 0.4 µmol/L, UV = 125 µW/cm2, pH = 7.5 ± 0.1, t = 2 h). Water quality parameters (NO3−, Cl−, SO42−, humic acid (HA)) showed quite different effects on SD decontamination. Simulated degradation experiments using real samples demonstrated that PPTD membrane filtration-photocatalysis system has significant potential with regard to controlling SD as pollutants in water. The photocatalytic mechanism characterized using ESR indicated that OH was largely responsible for SD decontamination. The mechanism of the PPTD membrane filtration-photocatalysis system suggests that TiO2-Dopamine could exist synergistically through the bidentate structure or the chelated structure, and that OH, O2−, HO2, H2O2 and 1O2 may be produced in the PPTD membrane filtration-photocatalysis system.