Electrochemical treatment of benzoic acid (BA) from aqueous solution and optimization of parameters by response surface methodology (RSM)

Abstract

The present research work is based on the degradation of benzoic acid (BA) and chemical oxygen demand (COD) from laboratory prepared aqueous solution. An electrocoagulation approach using aluminum (Al) and iron (Fe) as electrode material is applied in this study. A full factorial (4-factors, 5-level, and 3-response) rotatable central composite design in response surface methodology was developed for optimization of process parameters. Operating parameters such as pH (4–12), current density (A/m2)—(76.00–230.00), electrolysis time (min)—(15–90) and electrolyte concentration (NaCl) (g/L)—(0.5–1.5) are chosen for the study. Maximum % removal efficiency of BA—70.52, 64.42; COD—65.65, 60.70 and E. consumption (kWh/kgCODremoved)—102.89, 133.52 are achieved at optimal operating conditions by Al and Fe electrodes respectively. Sludge samples generated after EC treatment at optimum treatment conditions are also analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, TGA/DTA (thermo gravimetric analysis and differential thermo gravimetric analysis, FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction). Settling characteristics of sludge samples are also studied for both Al and Fe electrodes.