Application of Wastewater Reuse with Photocatalyst Prepared by Sol-Gel Method and Its Kinetics on the Decomposition of Low Molecular Weight Pollutants

Abstract

The development of immobilized photocatalyst as a strategy for problematic electronics wastewater reuse is described in this study. The strategy was to perform separate rinsing, mostly consisting of low molecular weight compounds, and to decompose them with a simple process, based on the advanced oxidation process (AOP). Extensive studies were performed on the preparation conditions of immobilized photocatalysts by sol-gel method under various amount of precursor and support, water to precursor ratio, pH, aging time, and calcination conditions. The optimized preparation conditions were chosen by measuring removal efficiencies of isopropyl alcohol as a representative target compound with supportive SEM and XRD analyses. Removal efficiencies with photocatalyst and UV irradiation in synthetic wastewater simulating electronics wastewater were evaluated over time. Removal efficiencies of alcohol, acetone, ethanol, and acetaldehyde reached 97.2%, 71.2%, 99.0%, and 99.0%, respectively, in 2 h. Reaction constants of each compound were determined by fitting experimental data to the first order kinetic equation and the trial and error method with consecutive reaction pathway. As analysis results of reaction constants, UV with prepared photocatalyst was found to be effective and the decomposition of acetone was found to be the rate-determining step. The immobilized photocatalyst developed in this study would be useful for application of wastewater reuse with high removal efficiencies, mild preparation conditions, and mechanical stability.

Recent Advances in Advanced Oxidation Processes for Degrading Pharmaceuticals in Wastewater—A Review

“…There are various established AOPs, which are dominantly classified into UV-hydrogen peroxide (UV/H 2 O 2 ), Fenton and photo-Fenton, ozone-based processes, photocatalysis, and physical processes (including sonolysis, microwave, and electron beam irradiation) [24]. Among these AOPs, photocatalysis is the simplest method, and photocatalysts can be reused multiple times in wastewater treatment [38]. A large number of research efforts employing metal oxides, such as TiO 2 , ZnO, WO 3 , and ZnWO 3 nanoparticles as photocatalysts activated by UV light irradiation, have been devoted to the removal of pharmaceutical compounds from aqueous solutions [39].…”