Modeling sustainable photocatalytic degradation of acidic dyes using Jordanian nano-Kaolin-TiO2 and solar energy: Synergetic mechanistic insights.

ABSTRACT

The abstract highlights the global issue of environmental contamination caused by organic compounds and the exploration of various methods for its resolution. One such approach involves the utilization of titanium dioxide (TiO2) as a photocatalyst in conjunction with natural adsorption materials like kaolin. The study employed a modeling-based approach to investigate the sustainable photocatalytic degradation of acidic dyes using a Jordanian nano-kaolin-TiO2 composite material and solar energy. Mechanistic insights were gained through the identification of the dominant reactive oxygen species (ROS) involved in the degradation process, as well as the synergetic effect between adsorption and photocatalysis. The Jordanian nano-kaolin-TiO2 composite was synthesized using the sol-gel method and characterized. The nanocomposite photocatalyst exhibited particle sizes ranging from 27 to 41 nm, with the TiO2 nanoparticles well-dispersed within the kaolin matrix. The efficacy of this nanocomposite in removing Congo-red dye was investigated under various conditions, including pH, initial dye concentration, and photocatalyst amount. The optimal conditions for dye removal were found to be at pH 5, with an initial dye concentration of 20 ppm, and using 0.1 g of photocatalyst, resulting in a 95 % removal efficiency. The mechanistic insights gained from this study indicate that the hydroxyl radicals (•OH) generated during the photocatalytic process play a dominant role in the degradation of the acidic dye. Furthermore, the synergetic effect between the adsorption of the dye molecules onto the photocatalyst surface and the subsequent photocatalytic degradation by the ROS was found to enhance the overall removal efficiency. These findings contribute to the fundamental understanding of the photodegradation mechanisms and guide the development of more efficient photocatalytic systems for the treatment of acidic dye-containing wastewater. The use of solar power during the purification procedure also leads to cost reduction and strengthens sustainability efforts.