Coupled electrochemical processes for removing dye from soil and water

Abstract

In this work, a coupled remediation approach is studied by using electrochemical technologies (electrokinetic remediation (ER) and after that, BDD-electrolysis) to remove an azo dye from soil and after that, the elimination of dye from generated effluents was also attained. ER experiments were carried out using graphite electrodes, by applying 1 V cm−1 for 14 d, investigating the use of solutions containing with 0.05 M of Na2SO4 and 0.05 M of sodium dodecyl sulfate (SDS) in the anodic and cathodic reservoirs, respectively. The results clearly indicated that SDS favors the elimination of organic pollutant from the soil, achieving 65%. However, the removal efficiency is increased (89%) when sodium sulfate solution was used as supporting electrolyte. The transport of organic compound in the soil from the cathode to anode reservoir was due to the electromigration phenomenon. Toxicity tests were performed to evaluate the reuse of the soil after remediation, then, the germination of sunflower seeds was carried out, achieving significant percentage of germination in central soil positions (65% and 92%). Finally, the effluent generated by ER was treated with BDD-electrolysis, obtaining complete discoloration after 80 min and a quasi-complete elimination of organic matter (more than 95%) after 120 min due to the contribution of persulfate (S2O8 2−) electrochemically generated at BDD anode.