Construction and evaluation of a CSTR reactor for the treatment of textile effluents. (Atena Editora)

Abstract

The textile industry, which is influential in the Brazilian economy, generates effluents that cause various environmental impacts when discharged into water bodies, altering the color, transparency, pH and temperature of the water, damaging the photosynthesis of aquatic plants and, consequently, marine life. In addition, they compromise the ecological balance, exacerbating the damage to the environment. A common example is eutrophication, caused by excess nutrients in effluents, which stimulates excessive algae growth, reducing oxygen levels. It is therefore essential to continue investigating alternative methods to reduce pollution and ensure sustainability in the textile sector. Therefore, this study investigated the kinetics of the reaction between the Crystal Violet dye and NaOH in a CSTR reactor, built by the authors, with the aim of determining the reaction's rate constant, evaluating its order, determining the system's conversion and the model that best describes it. In this way, the integral and equally spaced points methods were implemented, respectively, to define the kinetic rate constant of the reaction and its order, and, in the end, the pseudo-first order kinetics methodology was used, since the reaction was monitored using the Crystal Violet reagent. To help monitor the behavior of the reaction, a computer model of the system was proposed, from time 0 to 25 min, which showed the height and volume profiles of the CSTR and the concentrations of the reagents. The time conversion of the system, obtained experimentally, was significant, reaching 81.84%, which attests to the efficiency of the system. In order to better describe the CSTR reactor and represent a real system, approaches such as segregation, tanks in series, dispersion, ideal models and CSTRs with dead zones were considered preferential channels. Finally, the results indicated that the series tank model best describes the reactor.