Highly-efficient degradation of amiloride by sulfate radicals-based photocatalytic processes: Reactive kinetics, degradation products and mechanism

The capability of palladium (Pd) nanoparticles photo-deposited on BiVO4 (BV) nanosheets support to effectively activate persulfate (PS) and degrade pharmaceutical residues amiloride (AML) in aqueous solution under visible light was investigated. The removal efficiency of AML in Pd/BV/PS/vis system reached to 96.43% within 30 min as compared to only 50.73%, 70.87% and 77.70% in BV/vis, Pd/BV/vis and BV/PS/vis respectively under the identical experimental conditions. One inherent reason for the enhanced performance was possibly owing to the fact that visible light absorption of photocatalyst was improved through the surface plasma resonance (SPR) effect of Pd nanoparticles. For another respect, the photo-induced electron-hole pairs separation rate was firstly strengthened with Pd as electron traps and then by PS oxidants as electrons acceptors. Influencing factors including PS dosage, AML concentration, humic acid (HA) concentration, coexisting anions and cations and water sources on the AML degradation in the Pd/BV/PS/vis system were explored in details. Higher photocatalytic activity was still maintained in raw wastewater containing dyes, phenols and antibiotics. More generation of oxidative species such as O-center dot(2)-, (OH)-O-center dot and SO4 center dot- were verified by radical quenching experiment and electron spin resonance (ESR) test. The major products of AML decomposition were identified and the correspondent degradation pathways were also proposed. This founding allows for the construction of highly efficient BV-based photocatalysts and provides a new opportunity for the treatment of wastewater containing refractory pollutants by SO4 center dot- based advanced oxidation processes (AOPs).