Proof of Concept for the Organic Electrorefinery Technology with Actual Effluents

This work describes results of a first proof of the concept of electrorefinery with a real waste obtained from a cashew nut factory, and it shows the effect of the current densities of both the anodic oxidation and electrochemically assisted separation processes on the performance of the system. Results obtained demonstrate that electrorefinery is a promising option to minimize the carbon fingerprint, worth studying for increasing the sustainability of the environmental remediation of wastes, because valuable species can be obtained from the destruction of pollutants and recovered within the same integrated process. They also point out that there is still a long way to reach an optimum solution for this technology, but it is worth the effort to be made. Many different carboxylates were detected, but oxalate was the primary product both in the reaction tank and in the recovery tank. The production is almost linear during the electrolysis, with a reaction rate of 23.3 mg C h^-1 in the case of oxalate and a separation ration of around 20% in the electrodialysis stage. There is a negligible crossover of aromatic species into the recovery solution, which becomes an important advantage for further processing of the carboxylate solutions in the search to valorize these species in terms of circular economy principles. Energy efficiencies in the range of 0.04-0.21 mg C-carboxylates (Wh)^-1 and Coulombic efficiencies in the range 0.92-2.03 mg C-carboxylates (Ah)^-1 were obtained in this work. A life cycle assessment indicated carbon dioxide and water footprints as low as 0.31 g of CO₂ mg^-1 C and 30 mL of H₂O mg^-1 C recovered in the products obtained, respectively.