Comparative study of powder and cotton-supported BiOCl particles on the photocatalytic degradation of industrial pollutants

Abstract

This work compares the photocatalytic performance of powder and supported bismuthoxychloride (BiOCl) catalysts. Semiconducting nanoparticles (NPs) were immobilised onto cotton fibres (Cot) to prepare photoactive hybrid materials (Cot-BiOCl) for application in environmental remediation and facilitate catalyst recovery. The cotton modification was accomplished using simple in situ methodologies of reactant impregnation followed by BiOCl synthesis in water at room temperature. Using this methodology, it was possible to load 14 mg of BiOCl NPs per gram of modified cotton. The as-prepared material absorbs mainly in the UV range. However, after an easy in situ light sensitisation of the BiOCl, and due to the formation of oxygen vacancies on the catalyst surface, the sensitised material (BiOClUV) starts to absorb in the visible range. Its bandgap energy, Eg, shifts from 3.37 to 1.99 eV thus allowing its use under visible light. The photoluminescence (PL) analysis suggests lower recombination rate of the electron-hole pairs conferring enhanced photoactivity to the self-sensitised BiOCl. Under UV–visible light irradiation the Cot-BiOCl photocatalytically degraded a range of collagen dyes with high efficiency, ≥ 73% in 1 h. After light sensitisation, the modified cotton fibres also allow a swift degradation of collagen dyes at a lower cost under visible light irradiation, 88 ≥ removal % ≥ 45, within 3 h. Additionally, the composite reutilisation and the contribution of the substrate architecture on the composite stability is highlighted. The approach used, along with the high activity of the catalyst, displays better economic viability for application in industrial pollutant removal by enabling efficient use of solar light, and an easy and swift catalyst recovery.