Study on the interaction of anions and cations in the synthesis of nanoflower bismuth silicate and its photocatalytic removal of dyes and antibiotics

Abstract

It is challenging to construct photocatalysts with excellent adsorption-photocatalytic synergy and multi-system pollutant degradation by utilizing double heterostructure with unique nanoflower structure and energy band modulation. Here, a nanoflower-like double-heterojunction composite photocatalyst with high visible light activity is prepared in situ by ion exchange, namely BOSBM (M=I, B, C, K, L; the modified ions are I-, Br-, Cl-, K- and Li-). On the other hand, surface-charged ions provide multiple adsorption sites for pollutants. In BOSBC-6 (the ion is Cl-, the concentration is 1.05 mol/L) photocatalyst, the photocatalytic performance (10 min, degradation rate of 98 %) is 4 times that of BOS. It still has excellent catalytic stability (30 min, 98 % degradation rate) even after 3 cycles of testing. Meanwhile, BOSBM exhibited high degradation efficiency for dye (RhB) and various antibiotics (norfloxacin, ciprofloxacin, and tetracycline hydrochloride). Due to its upward shifting structure (Vo level), BOSBM plays an important role in the degradation of multi-system pollutants. In particular, the formation of Bi2O2SiO3-BiOCl and Si2Bi24O40-BiOCl double heterojunctions in BOSBC-6, which significantly improves the separation efficiency and increases the redox capacity of the sample. Therefore, this work broadens the application range of bismuth silicate photocatalysts and provides a new strategy for obtaining photocatalysts with excellent adsorption-photocatalytic synergistic effect by utilizing the heterojunction structure for modification purposes.