Degradação fotocatalítica do princípio ativo sulfametoxazol em reator de leito fixo com recirculação contínua utilizando radiação artificial

Abstract

The microcontaminants occurrence, such as pharmaceuticals found in the environment, causes concern about the environmental impact of the pollution from anthropic activities. Thus, this work aimed the evaluation of the photocatalytic system efficiency in removing the sulfamethoxazole active principle, using the titanium dioxide (TiO2) catalyst impregnated in grinded glass with two different particle sizes. The catalyst impregnation was performed by two methods: A overlay and B solvothermal. The obtained materials were characterized by total reflection X ray fluorescence (TXRF), X ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), thermogravimetry (TG) and nitrogen physisorption. Considering the results, the TiO2 was verified in the grinded glass carrier, achieving a 2.5% immobilization proportion. The DRX analysis evidenced the presence of the anatase crystalline phase in the catalyst of used methods. Method A achieved the best catalyst fixation on the carrier. The photocalytic assays indicated a SMX removal of 97% for method A and 71% for method B after 360 minutes of reaction. The kinetic analysis indicated the pseudo first order model as the one that best fit the experimental data with degradation constants of 0.008 and 0.004 min-1 for the SMX methods A and B, respectively. The system efficiency is reduced as a function of the photodegradation assays reproducibility due to the catalyst loss by erosion to the SMX aqueous phase. The difference on the efficiency between methods A and B is probably due to the different proportion of anatase crystalline phase that is present in each support impregnation method. According to the toxicological essays, the treated samples presented higher toxicity when compared to the raw one, which possibly occurred because of a partial mineralization of the SMX and the production of intermediate compounds.