Degradation of aqueous organic dye pollutants by heterogeneous photo-assisted Fenton-like process using natural mineral activator: Parameter optimization and degradation kinetics

Abstract Degradation of organic pollutants by heterogeneous Fenton-based advanced oxidation processes has been proved to be an efficient method. The use of naturally occurring catalysts as H 2 O 2 activators is of particular interest in environmental remediation. This work applied a low-cost and eco-friendly natural mineral under UV-light irradiation to degrade organic dye in water. To study the performance of the natural mineral in photo-Fenton oxidation, methylene blue (MB) was employed as a model dye pollutant. The morphology and chemical composition of the natural mineral were characterized using various techniques. The effects of different experimental conditions such as the initial pH of the solution, the amount of catalyst, and initial dye concentrations on the degradation efficiency were investigated. The degradation of methylene blue reached 91.3% at optimum reaction conditions; 0.1g catalyst and 100 mg L ‒1 H 2 O 2 concentrations for 10 mg L ‒1 initial dye concentration after 180 min of treatment. The pseudo-first-order kinetic model exhibited a better correlation coefficient (R 2 > 0.98) in explaining the degradation kinetics of MB. The applied natural mineral showed good catalytic activity and will open a door towards large-scale wastewater purification from dyes. Furthermore, the plausible mechanism of the heterogeneous photo-Fenton oxidation is discussed.