Enhanced photocatalytic activity of BiPO4 towards the photo-degradation of Rhodamine B: Effect of precursor phosphates (Na2HPO4, KH2PO4, and NH4H2PO4) on BiPO4 structure, morphology and optical properties

BiPO₄ was prepared by the precipitation route using three different types of phosphate salts (Na₂HPO₄, KH₂PO₄, and NH₄H₂PO₄) as starting precursor. The dissolution of each phosphate precursor used in distilled water gave a specific pH that affected the purity, morphology and optical properties of the BiPO₄ produced. BiPO₄ synthesized from Na₂HPO₄ showed the best photocatalytic activity towards the photo-degradation of Rhodamine B as a polluting dye. The effect of the precipitating agent on the structure, size and optical proprieties of the particles was confirmed by the X-ray diffraction technique, scanning electron microscopy, (BET) method, Raman analysis and Diffuse Reflectance Spectroscopy. Several organic and inorganic scavengers were used to evaluate the role of various photogenerated reactive species. The kinetic study followed the pseudo-first-order kinetic model. In addition, the proposed reaction mechanism for the degradation of Rhodamine B in the presence of the best photocatalyst was discussed.