Degradation of Lindane using two nanosized BiOXs and their heterojunction under visible light

Abstract

In this paper, bismuth oxybromide (BiOBr), bismuth oxyiodide (BiOI), and heterojunction (BiOI_0.5Br_0.5) were prepared via facile co-precipitation method, a low-temperature solution route, and facile chemical etching method, respectively. They were prepared by Bi(NO₃)₃·5H₂O as the Bi source. The resulting BiOBr, BiOI, and BiOI_0.5Br_0.5 photocatalysts were fully characterized using X-ray diffraction, energy-dispersive X-ray spectroscopic, scanning electron microscopy, high-resolution transmission electron microscopy, SAED, Brunauer–Emmett–Teller surface area, and UV–vis diffuse reflectance spectra techniques. The prepared photocatalysts were of pure tetragonal phase, and homogeneous particles. Their surface area are 6.19, 296.6, and 186.6 m²/g, and their band gaps were about 2.9, 1.9, and 2.1 eV for BiOBr, BiOI, and BiOI_0.5 Br_0.5, respectively. Their photocatalytic property was investigated by the degradation of Lindane in aqueous solution under commercial visible metal halide lamp. The optimum amounts of BiOBr, BiOI, and BiOI_0.5Br_0.5 powders were 1.0 g/L at pH 8 that degraded 60, 80, and 95% of Lindane, respectively, after 2 h of irradiation. Moreover, BiOI_0.5Br_0.5 heterojunction exhibited much higher photocatalytic activity for the degradation of Lindane under visible light (λ > 420 nm) than pure BiOBr and BiOI, Since, the reaction kinetic constants for degradation of Lindane by BiOBr, BiOI, and BiOI_0.5Br_0.5 heterojunction were 0.0073, 0.0126, and 0.0194 min⁻¹, respectively. It is a prospective strategy for constructing highly efficient bismuth halide-based heterojunction to eliminate organic pollutants in water.

Keywords:

• Visible light
• Degradation
• BiOX
• Lindane