Evaluation of Photocatalysis Based on Ozone/Goethite/Ultraviolet C for Caffeine Degradation

Abstract

Caffeine is considered as an emerging concern pollutant (EC), it is found in important concentrations due to bioaccumulation in the environment and the high resistance to conventional and biologically treatments. It has a critical effects on aquatic species and human health. Intensification of photocatalysis based on Goethite/UV and Ozone (ozone/Goethite/UVC) was applied in the degradation and mineralization of Caffeine in solution using a Heterogeneous Stirred Tank Photoreactor (STPR) with artificial light. Ozone dose and Goethite charge were established as perturbation variables and the effects of speed of agitation (rpm), pH, initial caffeine concentration and UV light were evaluated before the intensification for look the best conditions of the coupling. In addition, a kinetic analysis based on first order reaction rate law was done. The O3/UV/GHT process was effective for use as a technology in the treatment of water contaminated with caffeine reaching a degradation around of 99,97% in times less 20 minutes at conditions of the optimal values of 12,77 mg·min–1 of ozone dose and 0,2 g·L–1 of Goethite charge. The mineralization percentage achieved was 38,02% with optimal values of 3,84 mg·min–1 of ozone dose and 0,5 g·L–1 of Goethite. The system was satisfactorily described as a first order reaction type with a kinetic constant of 0,4581 min–1.