Performance of indirect electrochemical processes using transition metal oxide electrodes for the abatement of food dye in aqueous solution

Abstract

The present study aims to evaluate the effectiveness of a transition metal oxide electrode, specifically Ti/Ru0.3Ti0.7O2, in tackling the removal of tartrazine (TTZ) dye from an aqueous solution. Operational factors such as pH (3–10), current densities (2.5–10 mA cm−2), diverse electrolytes, and dye concentration were investigated in bulk electrolysis. The UV–visible spectrophotometer was used to regularly track the progression of dye discoloration, while total organic carbon analysis was employed to assess mineralization levels. The electrodes were subjected to in situ characterization using cyclic voltammetry in distinct electrolytes – Na2SO4 and NaCl. Additionally, the electrode's surface morphology and composition were scrutinized through techniques such as scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction analysis. Results indicated that the electrochemical degradation of TTZ) was notably more effective at higher applied current densities (10 mA cm−2) and increased NaCl concentrations (0.04–0.08 M) within the acidic environment (pH = 2–6). Moreover, the degradation of TTZ exhibited greater efficiency at lower dye concentrations compared to higher doses. Among the various electrolytes, NaCl was identified as the most effective supporting electrolyte due to its superior dye degradation efficiency and lower energy consumption due to chlorinated oxidants, leading to faster dye removal.