Activation of sodium percarbonate by vanadium for the degradation of aniline in water: Mechanism and identification of reactive species

Sodium percarbonate (SPC)-based advanced oxidation process has been applied to the wastewater treatment in recent years. In the present study, a novel catalyst utilization of vanadium(V) was investigated for the activation of SPC for aniline degradation. The mechanism of SPC activation by V(IV) was demonstrated, and the major free radicals were identified through scavenging tests and electron paramagnetic resonance (EPR) analysis. The performance of aniline degradation was evaluated in the V(IV)/H2O2 and V(IV)/H2O2/Na2CO3 systems and compared with that of the V(IV)/SPC system. The influences of initial pH and effects of inorganic anions were also studied. The results show that aniline could be decomposed efficiently by SPC activated with V(IV) and the degradation efficiency increased with the increase in V(IV) and SPC dosage. O2−, CO3−, and OH were found to participate in aniline degradation, and O2− and CO3− were confirmed to be the predominant species. The decomposition of aniline was enhanced when equal amount of H2O2 was utilized instead of SPC under acidic condition while a comparative behavior was achieved in the V(IV)/H2O2/Na2CO3 system. Furthermore, aniline degradation was not impacted significantly by the initial pH and addition of Cl−, SO42− and NO3−, while HCO3− led to a betterment of aniline removal. These results indicate that the V(IV)/SPC system is an effective and promising approach for the removal of aniline from water for its feasibility and stability, which achieves eliminating contaminants by another waste.