Cavitação hidrodinâmica: degradação do corante azul de bromotimol na presença do peróxido de hidrogênio

Abstract

Due to urbanization, increased industrial activities and technological development, man has modified the way he uses natural resources, compromising the quality of water, soil and air. The conventional treatments of water and effluents do not remove all types of chemical compounds, therefore, there has been a need for research that involves advanced processes in the treatment of these pollutants. The aim of the current study was to employ hydrodynamic cavitation for the degradation of bromothymol blue dye. Experimentally, saturated dye solutions were submitted to the hydrodynamic cavitation process in Venturi reactor. The routes were defined by the Central Compound Planning (CCP), which optimized the variables pressure, time and molar ratio of peroxide. The dye degradation efficiencies were evaluated from the analysis chemical oxygen demand (COD) and the color removal before and after treatment in the Venturi. The best experimental conditions obtained in the experiments were a time of 25 minutes, pressure of 4.0 bar and molar ratio of dye and peroxide of 1:30. The degradation kinetics-reaction order was 3.5. Afterwards, a tannery effluent was submitted to optimized conditions to validate the practical efficiency of the process. The removal efficiencies of bromothymol blue dye were similar in terms of COD and discoloration, resulting in degradation rates above 90%. For the effluent tannery COD removal was 88%. The efficiency of the process results from the synergistic effect of the combination of cavitation and hydrogen peroxide on mineralizing the dye. The cavitation system with a Venturi device has great potential to remove dyes from industrial effluents in a short period of treatment.