Interfacial engineering of BiVO4/PANI p-n heterojunction for enhanced photocatalytic degradation of p-nitrophenol: Pathway, toxicity evaluation and mechanistic insights

The presence of organic micro-pollutants (OMPs) in the water sources is a major threat to the aquatic and human health and also affects the wastewater treatment process. p-Nitrophenol (p-NP), has been extensively used as raw materials in various chemical industries. The present study focused on the development of BiVO4/PANI nanocomposites (NCs) for enhanced photocatalytic degradation of p-NP under visible light irradiation. The morphology, chemical composition and crystallinity of the prepared NCs was characterized by XRD, XPS, FE-SEM, RAMAN, EIS and TEM, and the optical properties of the NCs were determined by UV–vis DRS, and PL analysis. Compared to the bare BiVO4 and PANI, the NCs showed a better performance against p-NP (98.25 %) and had good cycle stability (91.91 % after six cycles). The enhance photocatalytic performance of the NCs is ascribed to the synergistic effect and the p-n heterojunction formed between BiVO4 and PANI. Furthermore, several tests were done to determine the effect of pH, NCs and p-NP concentrations and influence of various ions were also studied. Scavenger experiments revealed that •OH, and h+ contributed significantly in the degradation process of p-NP. The intermediate metabolites were identified, and toxicity of the by-products was elucidated by using GC–MS and ECOSAR program respectively. The reusability of the material was assessed by repeating the degradation experiment for 6 consecutive cycles. This work underlines the promising potential of BiVO4/PANI NCs for efficient treatment of toxic pollutants bearing wastewater.