Electrolytic removal of alizarin red S by Fe/Al composite hydrogel electrode for electrocoagulation toward a new wastewater treatment.

This paper studies Fe/Al composite hydrogel electrode electrocoagulation (EC) and adsorption of alizarin red S (ARS). ARS removal efficiency and degradation mechanism when applying Fe/Al composite hydrogel electrode were investigated. The optimum experimental factors and degradation of ARS were discussed. ARS degradation was optimal operation at initial pH 3 with O2.The experimental results showed that the COD removal efficiency was better, reaching to about 90 % when applying the novel electrode system. The discoloration rate also reached the best effect of 99 % in the superior technical conditions. The optimum electrolysis time is about 30 min. Results revealed that the efficiency in the EC process with Fe/Al composite hydrogel electrodes were much better than that in conventional electrode system. In addition, Fe/Al composite hydrogel electrodes are environment-friendly material, which reuse waste and reduce cost. Hydrogel has certain iron exchange capacity to eliminate the residual metal irons. It is found that the application of ultrasonic helps to accelerate the electrocoagulation of ARS. This study not only realizes the ultrasonic, flotation, coagulation, and adsorption of the combination but also gains economy and environment. Consequently, the unique performance of Fe/Al composite hydrogel electrodes opens promising perspectives for fast, high, and economical treatment of wastewater containing dyes or/and organic contaminants.