Influence study of cationic surfactant, temperature, and current on the electrocoagulation process for removal of Remazol Red RB 133 by central composite design and response surface methodology

The optimization and modeling of the electrocoagulation process which conducted by means of current density (X₁), temperature (X₂), and CTABr surfactant concentration (X₃), in the removal of Remazol Red RB 133, were performed through the response surface methodology (RSM). The experiments were conducted in a batch reactor with 304 stainless steel electrodes connected in parallel monopolar configuration. The response surface methodology (RSM) was used to measure the removal of dissolved organic carbon (DOC) (Y₁), dye (Y₂), and current efficiency (Y₃). The analysis of variance for the predicted models of the responses showed that they were statistically satisfactory and had a high coefficient of determination ( \({R}_{{Y}_{1}}^{2}=\) $R_{Y_1}^2=$ 0.8424, \({R}_{{Y}_{2}}^{2}=\) $R_{Y_2}^2=$ 0.8952, and \({R}_{{Y}_{3}}^{2}=\) $R_{Y_3}^2=$ 0.9534). The optimized conditions of 0.7 A, 35 °C, and 0.75 mmol L⁻¹ were found to achieve removal rates above 88% and were also effective in the treatment of textile effluent in a continuous system. The removal rates for DOC and dye were 88.16% and 99.97%, respectively, with a current efficiency of 60.7%. The results of theoretical studies, practical tests, and HPLC and GC–MS analyses indicated that the removal of the RRRB133 dye may be governed by simultaneous mechanisms of sweeping flocculation and degradation reactions.