Removal of sulfadiazine in a modified ultrafiltration membrane (PVDF-PVP-TiO-FeCl) filtration-photocatalysis system: parameters optimizing and interferences of drinking water.

The addition of Fe to TiO is one of the effective methods to inhibit the recombination of photogenerated electrons and holes and thus improve the photocatalytic activity of TiO. The effect of PVDF-PVP-TiO-FeCl (PPTFe) membrane filtration-photocatalytic system on the removal of trace concentration of sulfadiazine (SD) in water was evaluated. A two-factor four-level experiment was established to optimize 16 self-made modified membranes. The optimal membrane was then characterized in seven tests (SEM, EDS, membrane pure water flux, contact angle, porosity, mean pore size, ATR-FTIR), resulting in the optimal ratio (PPTFe membrane with 1.2 wt%TiO and 0.8 wt%FeCl). Compared with the original membrane, the pore number, pore size, permeability, and hydrophilicity of the PPTFe membrane were all enhanced. The removal efficiency (92.63%) of SD by PPTFe membrane filtration-photocatalysis system was investigated. The reaction rate (0.0214 min) of the removal SD of the system was determined according to the pseudo-first-order kinetic model. The removal performance of membrane type, pH, and water quality parameters (Cl, SO, NO, HA) on PPTFe membrane filtration-photocatalytic system were also made a deep inquiry. The results reflected that acidic conditions (pH = 3) were beneficial to SD removal, the presence of Cl, SO, and HA could inhibit SD removal, while the existence of NO was unaffected. Furthermore, the removal rate of SD in the actual water body was displayed well in this system. Finally, the possible photocatalytic degradation mechanism was proposed.Graphical abstract.