Otimização de sistema em linha para degradação de corantes têxteis em águas residuais.

Abstract

This work proposes a closed inline system for degrading the indigo blue 7.5, green 347, and red 343 textile dyes. The system was constructed using a PTFE tube with a diameter of 0.8 mm and a UV lamp of 15 W. The solutions containing the dyes circulated through the system after adding 30% hydrogen peroxide. The optimization was carried out using a 2³ two-level full factorial design involving the variables flow rate of the dye solutions in the system, degradation time, and the coil length in the UV degradation region. Triplicates of the central point were performed to determine the pure error and the curvature test. The system's efficiency was evaluated through the discolorations of the solutions, measured by the absorbance in the specific wavelengths for each dye. The system showed satisfactory results for the three dyes with a minimum discoloration rate of 96%. The UV energy dose required for discoloration was calculated.

A system counting activated carbon columns for textile dye retention was also developed. Optimization was performed using a 2³ full factorial design, with column length, dye flow rate, and activated carbon mass as factors. The response was observed through the absorbance of the resulting solutions.