Ternary Ag/AgCl/BiOCl synthesis and the effects of its constituents on phenol degradation

Abstract

Mineralisation of organic constituents in wastewaters emanating from petrochemical processing plants, coal powered energy generation, nuclear power and processing of algal infested waters could render the waste streams reusable for the purpose of reduction of water consumption and protection of the environment from harmful pollutants. Semiconductor photocatalysis, a particle physics based class of advanced oxidation processes (AOPs) has been tried as greener technology for removal of organic pollutants in gaseous phases (e.g. air and steam) and in aquatic phases. Pioneering investigators utilised titanium as a photocatalyst using UV light as the energy source resulting in an electron band-gap of 3.2 mV. The UV lamps consumed a lot of electricity which makes the technology operationally non-feasible. This study focussed on the synthesis and evaluation of an alternative photocalyst comprised of Ag/AgCl/BiOCl with the potential of achieving photocatalysis of organic compounds under solar irradiation. All degradation tests were carried out on synthetic phenol wastewater. The effect of the components that make up the composite was also investigated. The catalysts were characterised using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR). The degradation efficiency of Ag/AgCl/BiOCl, AgCl/BiOCl and BiOCl under UV light were 60 %, 56 % and 55 %. The visible light irradiation achieved degradation of 52 %, 51 % and 15 % for the same catalysts after 4.5 h of irradiation. These results suggest a more practical and realistic application of photocatalysis in the industry through the development of a visible-light responsive catalysts.