Application of Box-Behnken Design and Steepest Ascent Approaches for Textile Wastewater Treatment Using Spinel Ferrites Composite

Abstract To reuse treated wastewater and avoid environmental contamination, effluent from textile industries needs suitable treatment. The Fenton-like oxidation process, using prepared Spinel Ferrite-activated carbon (AC) catalyst MFe₂O₄/AC (M = Ni, Co, Cu) through the sol-gel method was applied to treat pre-treated textile wastewater. Characterization was carried using different techniques, scanning electron microscopy (SEM) which reveals that the surface of the activated carbon is covered by aggregates of the ferrites. Vibrating sample magnetometer (VSM) measurements show that all three ferrites are magnetic in nature. The Brunauer, Emmett and Teller (BET) method indicate that NiFe₂O₄/AC has the largest surface area (1030.2515m²/g) and the highest total pore volume (0.728953cm³/g). The best catalyst was selected by trying two different pH (3, 8.21), two catalyst loadings (CL = 0.1 and 1 g/L), and three different concentrations of hydrogen peroxide (HPC = 1.10 and 50 milimolar). The CL, pH, and HPC were optimized using the Box-Behnken design as a response surfaces methodology to maximize the TOC removal. The statistical results yielded a coefficient of correlation R² equal to 0.97 and a p-value less than 0.01 for CL, HPC, the quadratic term CL², and the two interactions CL*pH and CL*HPC. The 3D surface responses allowed the investigation of the optimum conditions, the highest percentage of TOC removal rates attained by the experiments and the model are 79.04% and 82%, respectively with 1.5 g/L of CL, pH = 3 and 1mM (milimolar) of HPC. A comparison of TOC removal using the steepest ascent and Box–Behnken approaches reveals that the latter is a more efficient method of optimizing textile effluent. Based on these results, the Fenton-like process using spinel ferrite-activated carbon catalysts not only provides high performance but also highlights a new approach for the wastewater treatment sector which is a promising combining process to reuse treated wastewater.