Investigation of the effect of different electrode connections on the removal efficiency of Tartrazine from aqueous solutions by electrocoagulation

This study investigates the influence of variables on the decolorization efficiency of a solution containing Tartrazine (a synthetic yellow azo dye) by D.C. electrocoagulation (EC). The efficiency of different electrode connections and materials (iron, aluminium) for color removal is compared. Current density, time of electrolysis, interelectrode distance, supporting electrolyte concentration and pH of the solution were the variables that mostly influenced the color removal. Initially, a simple electrochemical cell was prepared with an anode and a cathode, then the effect of each variable was studied separately using aqueous Tartrazine in a batch mode. For a solution of 40 mg l−1 Tartrazine + 400 mg l−1 NaCl with chemical oxygen demand (COD) of approximately 30 mg l−1, almost 100% color and 90% COD were removed, when the pH was about 5.78, time of electrolysis was approximately 6 min, current density was approximately 120 A m−2 and interelectrode distance was 1.5 cm. In the second series of experiment, the efficiency of EC cells with monopolar electrodes in series and parallel connections and an EC cell with bipolar electrodes was compared with that of a simple electrochemical cell. The results revealed that EC cell with monopolar electrodes in series connection was more effective where aluminium electrodes were used as sacrificial and iron was used as anode and cathode. Electrocoagulation with Fe/Al (anode/cathode) was more effective for the treatment process than Fe/Fe electrode pair.