Direct complexation of citric acid to synthesize high-efficiency bismuth vanadate through molten polymerization route for the degradation of tetracycline hydrochloride under visible light irradiation

Abstract

Tetracycline hydrochloride (TH), a major broad-spectrum antibiotic with a tetracene structure, is widespread in surface water, but cannot be effectively removed by common water treatment processes. BiVO₄ (Bismuth Vanadate), as an environmentally friendly photocatalyst, has been widely researched in refractory organic pollutant mineralization. However, its easy recombination of photogenerated charges significantly restricts the practical application of BiVO₄. Given that the reported synthesis methods for efficient BiVO₄ either are complicated or require severe conditions and high cost, a practical and facile molten polymerization route with direct complexation of citric acid was developed in this work to synthesize a series of BiVO₄ photocatalysts with different morphologies. The as-prepared BiVO₄-0.05g CA shows a rough surface structure, and its reaction rate constant for the photocatalytic removal of tetracycline hydrochloride is 3 times better than that of bulk BiVO₄ under visible light irradiation. Furthermore, according to the results of the surface-area-normalized kinetic constants, in addition to a larger surface area, it was concluded that the higher surface O_ads/O_latt atomic ratio of BiVO₄-0.05g CA resulted in a stronger photocurrent and faster electron transfer rate. Thus, it exhibited an improvement of the photogenerated charges separation. The active radical capture experiments confirm that the photogenerated holes are the main active species. Moreover, the catalyst synthesized in this work not only exhibits better performance than other reported BiVO₄ catalysts, but also demonstrates excellent stability.