Degradação de metformina por fotocatálise heterogênea

Abstract

The development of pharmaceutical products for the treatment and control of chronic diseases has grown significantly as has its consumption which often occurs indiscriminately by the population. Currently, the drugs are already considered as emerging contaminants, because they are dispersed in small concentrations in Sewage Treatment Stations (ETE), Wastewater Treatment Plants (WWTP) and in rivers. In this context, metformin — antidiabetic — appears as a contaminant that is being detected in the aquatic environment in concentrations of ng.L-1 and µg.L-1. Given the need to eliminate this compound from the environment so that it does not cause, in the future, problems to aquatic life, the present work evaluated the efficiency of heterogeneous photocatalysis in its removal in a synthetic effluent at a concentration of 10 ppm. Catalysts synthesized by the sol-gel method were used in the photocatalytic tests and the best results were optimized against the reaction parameters catalyst concentration and pH. Among the catalysts employed after optimization, TiO2 presented greater efficiency in the degradation of metformin and the treated effluent obtained was evaluated by phytotoxicity. The root growth of Lactuca sativa seeds used for the phytotoxicity assays was 4.26 cm for the effluent treated against 3.94 cm for the positive control, this demonstrated that the residual concentration of metformin was not toxic.