Energy generation and abatement of Acid Orange 7 in reverse electrodialysis cells using salinity gradients

• The electrochemical abatement of Acid Orange 7 by reverse electrodialysis was studied.
• Energy generation and abatement of AO7 was achieved for the first time by RED.
• Mediated oxidation by electro-Fenton and active chlorine was carried out.
• The effect of the number of membranes and of salinity gradient was studied.

The simultaneous generation of electric energy and the treatment of wastewaters contaminated by an organic pollutant resistant to conventional biological processes, Acid Orange 7 (AO7), was achieved for the first time using proper redox processes by reverse electrodialysis using salinity gradients. The stack was fed with two aqueous solutions with different concentrations of NaCl and a synthetic wastewater contaminated by AO7. Various electrochemical approaches including electro-Fenton, electrogeneration of active chlorine (IOAC) and coupled process were performed in a stack equipped with 40–60 cell pairs and studied by focused electrolyses. The effect of the number of cell pairs and of the NaCl concentration of saline solutions was also investigated.