Removal of Congo Red and Rhodamine B Dyes from Aqueous Solution by Fenton Process: Optimization of Operational Parameters

Dye discharge in industrial effluents is a major source of concern, as its existence and accumulation can be harmful or carcinogenic to living organisms. This research focuses on using the Fenton process to treat dyes, Congo Red (CR) and Rhodamine B (RB), in aqueous solutions. The effects of the three independent variables considered for the optimization of the oxidative process: temperature, Fe (II), and H2O2 concentrations were evaluated using Response Surface Methodology (RSM). The experimental results are reported in terms of the degradation percentage of the dye. The optimal reaction conditions to degrade the congo red from aqueous solutions were: pH 3; T 298 K; 1.03 mM Fe2+ and 11.77 mM H2O2. The optimal reaction conditions to degrade the rhodamine B from aqueous solutions were: pH 3; T 298 K; 1.038 mM Fe2+ and 12.14 mM H2O2. Under these conditions and with a 120 min treatment, it was possible to reach 74.75 and 97.63 % of decolorization efficiency, for CR and RB, respectively. The model (R2) correlation coefficients for CR (congo red) and RB (rhodamine B) were 0.979 and 0.986, respectively, in the optimization. The Fenton process also showed a higher removal efficiency of RB compared to RC. RSM was clearly demonstrated to be one of the most effective methods for optimizing operating conditions in this study.