Removal of reactive textile dye from aqueous solutions by electrocoagulation in a continuous cell

In electrocoagulation (EC), coagulants are delivered in situ using the corrosion of sacrificial anodes when a DC voltage is applied. Simultaneously, electrolytic gases (H-2) are generated at the cathode. Aluminum and iron materials are usually used as anodes, the dissolution of which produces hydroxides and polymeric hydroxides. These coagulants are able to destabilize colloidal suspensions and emulsions, to adsorb, neutralize, or precipitate dissolved polluting species, and finally to form flocs that can be removed either by settling or flotation. The purpose of this study was to investigate the effects of the operating parameters, such as initial pH, initial concentration (C-0), residence time (), current density(j), and inlet flow rate (Q), on the removal of a red nylosan dye by EC process using aluminum electrode in a continuous electrochemical reactor. FTIR analysis was conducted to interpret the functional groups involved during the EC process. It was found that the increase in the current density up to 100Am(-2) had increased the dye removal efficiency and the optimum inlet flow rate for EC process was the minimum at 15Lh(-1) and it has increased the electrical energy consumption. A rate of abatement of about 90% for turbidity and 97% for color was observed, when the initial concentration of the dye C-0 was lower than 300mgL(-1), current density j=300A m(-2), conductivity =2.54 mScm(-1), inlet flow rate Q=15Lh(-1), residence time =35min, and initial pH ranged from 2.3 to 8.8. The specific electrical energy consumption was 19.5kWh per kilogramme of removed dye.