Application of central composite design (CCD) for optimization of cephalexin antibiotic removal using electro-oxidation process

Abstract In this work, the removal of cephalexin (CEX) from aqueous solutions using the anodic oxidation process was studied and four significant independent variables including contact time, pH, current density (CD), and initial CEX concentration were optimized using response surface methodology (RSM) involving a five-level central composite design (CCD). The degradation mechanisms and mineralization pathway of CEX were also proposed. To determine the removal and mineralization rate, chemical oxygen demand (COD) and total organic carbon (TOC) were determined. The optimum conditions were experimentally determined as follows: reaction time 52.68 min, pH 5.00, CD 44.69 mA/cm2 and initial CEX concentration 75.88 mg/L. The predicted and experimental removal efficiencies were obtained 100 and 97.38%, respectively. A good agreement between the experimental and predicted values was also observed with coefficient of determination of 0.95. Moreover, under the optimal conditions, 79.64 and 73.25% efficiencies were obtained for COD reduction and TOC removal, respectively, indicating the effectiveness of the developed method. Regarding the relatively low electrical energy consumption (41.28 kWh/kg COD), it can be claimed that the developed method is preferable to other processes in terms of energy consumption.