RESUMO
The treatment by Advanced Oxidation Processes (AOPs) of wastewater polluted with dyes is of particular interest in the field of environmental engineering, especially for the removal azo-dyes, representing over 50% of the global annual production of dyes. Unfortunately, most azo-dyes are non-biodegradable and can be toxic to aquatic organisms. This is the first data article that applies the methodology of response surface for the optimization of decolorization of an azo-compound using cobalt in a homogeneous medium as the catalyst of a bicarbonate activated hydrogen peroxide (BAP) system which, in turn, is an emerging technology for wastewater treatment. The Response Surface Methodology (RSM) based on a Central Composite Design (CCD) was used to evaluate and optimize the influence of three experimental variables (stoichiometric dosage of H2O2, molar ratio H2O2/NaHCO3 and cobalt concentration) on the decolorization of Ponceau 4R. Reactions were performed at 25⯰C, pH 8.3 with a reaction time of 2â¯h. Analysis of variance (ANOVA) showed values of R2 and adjusted-R2 of 0.9815 and 0.9648, and experimental data were fit to a second-order regression model. The optimal conditions to achieve a maximum decolorization (96.31%) of a Ponceau 4R aqueous solution of 20â¯mg/l were: 4.73 times stoichiometric dosage of H2O2, molar ratio H2O2/NaHCO3 of 1.70 and cobalt concentration of 11.16⯵M. Under the optimal reaction conditions, the influence of temperature (20, 25, 30 and 35⯰C) on decolorization was evaluated and data were adjusted to second order kinetics. To verify the efficiency of the BAP system on the decolorization of Ponceau 4R, under the optimal conditions of reaction, UV-Vis spectra, at different reaction times, were measured. Additionally, blank experiments in order to evaluate the effect of individual factors in the Ponceau 4R decolorization, using BAP system, were carried out. Data showed that the Co(II)-NaHCO3-H2O2 system is a suitable technology for the decolorization of azo-dyes aqueous solutions.
