A study on the boosted activity of the Bi2O3CeO2 nanoparticles toward phenazopyridine photodegradation; A brief comparison of the effects of some coupling strategies

Abstract

In the present study, some strategies were applied to fabricate binary coupled Bi₂O₃/CeO₂ systems and their roles in the boosted photocatalytic activity against the photodegradation of phenazopyridine. The individual Bi₂O₃ and CeO₂ nanoparticles (NPs) were mechanically mixed in agate mortar (MMix sample) in the first pathway. In the second pathway, the same prepared MMix sample was dispersed in n-hexane and ultrasonicated at 37 MHz for 15 min, and then the solvent evaporated (Ultra-MMix). In the third pathway, an ultrasonicated sample was prepared under the above-mentioned conditions on a mixture of Bi₂O₃ + CeO₂ NPs (Ultra-M sample). Finally, in the fourth sample, the binary catalyst was prepared via a precipitation procedure (Co-Pre). Some techniques like powder XRD, FTIR, SEM, and UV–Vis DRS were used to characterize the samples. Both Scherrer and Williamson-hall equations determined the crystallite size of the samples, conforming to the nano dimension for the crystals. DRS results showed a relative decrease in band gaps of the integrated systems compared to Bi₂O₃ alone. In the first initial steps of the photodegradation experiments, the activity of MMix and Co-Pre catalysts were evaluated against the PZP solution, revealing a boosted activity concerning the individual Bi₂O₃ and CeO₂ NPs. Due to the relatively higher activity of the MMix than the Co-Pre catalyst, the influences of the critical factors on its activity in the PZP photodegradation amount were optimized, and the optimal conditions of a Bi₂O₃:CeO₂ molar ratio of 1:1 for the coupled catalyst, C_PZP: 2 ppm, catalyst doe: 0.4 g/L, pH: 5, and illumination time of 90 min were reached. The pseudo-first-order kinetic model described the process kinetics. The effects of the scavenging reagents were also evaluated to estimate the relative role of the reactive species in PZP removal. Accordingly, the photoinduced holes and superoxide radicals showed higher relative roles in PZP photodegradation. A brief comparison on the effect of some fabrication roots in the photocatalytic activity of the coupled catalyst was applied.