Estudo da degradação fotocatalítica do fármaco Captopril pelo compósito de nanopartículas de TiO2 - perlita expandida

Abstract

Concern over the inappropriate disposal of chemicals in the environment has been increasing in recent years. Population growth has caused an increase in the consumption of water in the industrial, domestic and agricultural sectors, which has been affecting water quality. Drugs are prominent because they are biologically active substances that are difficult to break down. The Advanced Oxidative Processes (AOPs) can be used in the treatment of these pollutants, because it is an efficient technique in the mineralization of the contaminant. Heterogeneous photocatalysis can be used, being characterized by the use of semiconductors as photocatalysts. The most used semiconductor in this process is TiO2, presenting good degradation efficiency. However, TiO2 can be easily dispersed making the aqueous medium separation process difficult, and needs to be supported on some material. In this work, expanded perlite (EP), an aluminosilicate of volcanic origin, was used as support material. The study was carried out with captopril (CAP), a drug of the antihypertensive class. The synthesis of the composites de TiO2 – expanded perlite was based on the methodology described in the literature. The results show that the characterization techniques used in this study, FTIR, XRD, FRX, SEM, EDS and particle size analysis, showed that the TiO2 was incorporated in the PE matrix. The adsorption equilibrium time for the composites in the CAP drug solution was 30 minutes. The photolysis and photocatalysis tests indicated that the main effect between the two degradation methods is in relation to the time of analysis. The percentage of degradation with the best results was 10 mg L-1 for photolysis with 43.1% and for photocatalysis with 42.8%. The composite with higher content of TiO2 was more effective in the degradation. The kinetic study showed that kinetics is governed by the Langmuir-Heinshelwood model. The kinetics of the system was obtained as being of first order. The toxicity tests showed that the CAP had a negative influence on the germination and growth of the Lactuca sativa seeds and the treated effluents showed a similar performance to the positive control. The increase of the radiation intensity favors the degradation process, presenting better results for the composite T-PE-50% in the concentration of 10 mg L1 . The TOC analysis showed that the test with the concentration of 10 mg L-1 of CAP and with the composite T-EP-50% with power of radiation of 18 W had a better percentage of effluent mineralization, 39.8%. The energy cost study showed that the most economical process was for photocatalysis in the concentration of CAP of 10 mg L-1 in the power of radiation of 18 W and for the photolysis process in the concentration of CAP of 10 mg L-1 in the power of radiation of 18 W in the values of R$ 0.0570 and 0.0962, respectively.