Avaliação física e fotocatalítica para degradação de corante por meio de peças porosas de ZnO obtidas por rota não convencional

Abstract

Textile industries effluents are characterized as one of the most polluting in the world, since their removal is not efficient when done through conventional methods used by most industries. Advanced Oxidative Processes (AOP) are widely studied as alternatives for the treatment of these effluents, mainly through heterogeneous photocatalysis - a kind of AOP - which consists of activating a semiconductor by radiation, generating oxidizing, and reducing sites that will act in the degradation of the pollutants. The surface area of a photocatalyst is extremely important, as the AOP will activate and occur on its surface. Therefore, the use of semiconductor materials, such as ZnO, with high porosity and surface area becomes of paramount importance for the efficiency of the process and consequent water depollution. This project aimed to investigate the feasibility of producing porous green pieces of Zinc Oxide (ZnO) through the cold gelatinization technique (CG, an unprecedented technique and under development at the LABMAT laboratory at UNIFAL-MG) followed by firing by conventional route and by two-step sintering (TSS) for application in photocatalysis. After being produced by GF, the pellets with different compositions were physically characterized; the photocatalytic degradation potential was also evaluated, using Rhodamine-B dye. Pellets with high porosity, between 45 and 60%, and adequate mechanical strength for daily handling were obtained, with the best results being achieved when using the TSS technique. The results of photocatalytic degradation of the Rh-B dye were promising, with degradation rates above 40% in the best samples. It was possible to observe a greater photocatalytic potential when using 10 ml of 0.5M solution of Rhodamine-B in the photocatalytic assays, with 100% higher results when compared to the use of 15 ml.