Nanoarchitectonics of CuO/α-Fe2O3/BiVO4 photocatalysts with double heterojunctions on PVDF membranes: Investigating sulfadiazine removal and antifouling properties

The photocatalytic membrane combines membrane separation and photocatalysis, solving the problem of photocatalyst separation and recovery. In this study, the double-heterojunctional CuO/α-Fe2O3/BiVO4 (CBF) photocatalyst was successfully prepared and could degrade 98.59 % of sulfadiazine (SD) within 20 min, exhibiting good stability and universality. The experiment results demonstrated a significant contribution of O2− and h+ in the degradation of SD by CBF, and OH generated by Fe/Cu through the Fenton-like reaction triggered by photogenerated electrons also contributed to the degradation of SD. Meanwhile, PVDF/CBF immobilized photocatalytic membrane were prepared to remove 89.18 % of SD within 60 min in static water (100 mL of reaction solution, 10 mg/L of SD concentration, 0 mL/min of influent flow rate), and 92.96 % of SD within 180 min in a flowing water reactor (150 mL of reaction solution, 10 mg/L of SD concentration, 5.1 mL/min of influent flow rate). The experimental results show that the introduction of CBF increased the degradation rate of the membrane by 10 times (kPVDF = 0.003 min−1, kPVDF/CBF = 0.034 min−1). According to the FTIR results, the introduction of CBF also brought richer hydrophilic groups (–OH), and the contact angle testing further proved that the hydrophilicity of PVDF/CBF membranes was superior to that of bare membranes. The PVDF/CBF could also remove suspended solids in water through physical interception and achieve self-cleaning through chemical degradation of adsorbed organic pollutants. This work provides an efficient, low-energy, and environmentally friendly solution for the utilization of photocatalysis in practical situations.