Electrochemical Looping Green Hydrogen Production by Using Water Electrochemically Treated as a Raw Material for the Electrolyzer

In this study, the applicability of an integrated-hybrid process was performed in a divided electrochemical cell for removing organic matter from a polluted effluent with simultaneous production of green H2. After that, the depolluted water was reused, for the first time, in the cathodic compartment once again, in the same cell to be a viable environmental alternative for converting water into energy (green H2) with higher efficiency and reasonable cost requirements. The production of green H2 in the cathodic compartment (Ni-Fe-based steel stainless (SS) mesh as cathode), in concomitance with the electrochemical oxidation (EO) of wastewater in the anodic compartment (boron-doped diamond (BDD) supported in Nb as anode), was studied (by applying different current densities (j = 30, 60 and 90 mA cm−2) at 25 °C) in a divided-membrane type electrochemical cell driven by a photovoltaic (PV) energy source. The results clearly showed that, in the first step, the water anodically treated by applying 90 mA cm−2 for 180 min reached high-quality water parameters. Meanwhile, green H2 production was greater than 1.3 L, with a Faradaic efficiency of 100%. Then, in a second step, the water anodically treated was reused in the cathodic compartment again for a new integrated-hybrid process with the same electrodes under the same experimental conditions. The results showed that the reuse of water in the cathodic compartment is a sustainable strategy to produce green H2 when compared to the electrolysis using clean water. Finally, two implied benefits of the proposed process are the production of green H2 and wastewater cleanup, both of which are equally significant and sustainable. The possible use of H2 as an energetic carrier in developing nations is a final point about sustainability improvements. This is a win-win solution.