Facile novel acid coprecipitation synthesis of BiPO4 polymorphs: Enhanced photocatalytic degradation of the antibiotic AMX and the dyes RhB, MB and MO

Abstract

BiPO4 photocatalyst was synthesized by an acid coprecipitation route followed by heat treatments. The effect of the annealing process was correlated to the formation of BiPO4 polymorphs and the enhancement of photocatalytic activities. Bismuth phosphate calcined at 500 °C (BiP-500) showed the highest photocatalytic performance in the presence of Rhodamine B dye, due to the formation of both low-temperature monoclinic phase (LTMP) and high-temperature monoclinic phase (HTMP) on the one hand and the developed particle size on the other. The efficient photocatalyst was also used to photodegrade a wider range of organic pollutants: methylene blue, methyl orange and amoxicillin. The pH environment concerning the degradation of the anionic dye was studied and revealed increased activities in basic media. The radical superoxide species were highlighted as the major role in the photodegradation mechanism, according to the active radical species trapping experiments. Photoluminescence measurements performed under UV excitation revealed green and orange emissions with the greatest intensity in BiPO4 annealed at 400 and 450 °C.