Removal of Salicylic Acid from Aqueous Solutions Using Various Electrodes and Different Connection Modes by Electrocoagulation

Abstract

Removal of salicylic acid (SA) from aqueous solutions using hybrid aluminum and iron electrodes (eight different combinations) and three different connection modes (monopolar parallel (MP-P), Monopolar series (MP-S) and bipolar series (BP-S)) by electrocoagulation was investigated in this study. The effects of electrocoagulation parameters such as hybrid electrode combination, initial pH, current density, initial salicylic acid concentration, air injection flow, solution conductivity and connection mode on SA and COD removal efficiencies were evaluated. Optimum operational conditions at 10 min operating time were found to be as: Al-Al-Al-Al (anode-cathode-anode-cathode) electrode combination, the initial pH of 6, current density of 50 A/m(2), salicylic acid concentration of 100 mg/L, air injection mode of 2 L/min and connection mode of monopolar series (MP-S). Under these conditions, removal efficiencies for salicylic acid and COD were respectively observed as 95.1% and 85.97%. Moreover, the UV absorbance was determined before and after the treatments by electrocoagulation (EC) process. The operating costs including electrodes, energy and chemicals were calculated as 0.0156 (sic)/m(3). Sludge generation of EC process was also analyzed by scanning electron microscope (SEM) imaging, Fourier Transform Infrared Spectroscopy (FT-IR), XRD (X-raydiffraction) and amorphous Al hydroxides were encountered in the sludge. As to conclude, electrocoagulation through different electrode combinations and connections modes was found to be quite efficient for removal of salicylic acid from aqueous solutions.