Intensification of persulfate-mediated elimination of bisphenol A by a spinel cobalt ferrite-anchored g-C3N4 S-scheme photocatalyst: Catalytic synergies and mechanistic interpretation

Abstract

This study was designed to enhance wastewater treatment by the UVC/persulfate process via its coupling with spinel cobalt ferrite (SCF) nanoparticles anchoring graphitic carbon nitride (g-C3N4, GCN). The performance of SCF@GCN was assessed against bisphenol A (BPA) degradation as a model recalcitrant contaminant. Characterization tests confirmed the successful preparation of SCF@GCN with high photocatalytic activity and excellent capability in PS activation compared to plain SCF or pristine GCN. The results strongly pointed out that SCF@GCN combined with UVC and PS is capable to rapidly degrade BPA with a remarkable synergistic effect. Under optimum conditions (pH: 9.0, SCF@GCN: 0.3 g/L and PS: 4.0 mM), complete elimination of BPA (40 mg/L) was achieved in 15 min with excellent degradation kinetics (0.32 min−1). Scavenging experiments ascertained the generation of h+, 1O2 , O2•− , SO4•−, HO• species in SCF@GCN/PS/UVC system, indicating that both radical and non-radical mechanisms were involved during the degradation process. Furthermore, the developed process displayed a satisfactory performance for effective treating BPA-contaminated wastewater samples. Over 95% BPA was removed by the system after five catalyst reuse cycles, suggesting a cost-effectiveness potential in the reusability of SCF@GCN. A comprehensive mechanistic pathway for BPA degradation was proposed based on the reactive species and intermediates identified: A S-scheme heterojunction mechanism of photo-generated electron/hole pairs transfer in the SCF@GCN catalyst was found. Overall, our results present a promising technique with synergistic character for intensification of wastewater treatment.