Synergistic Production of Hypochlorite and Hydrogen through PEM Water Electrolysis

Abstract

Objectives : This study aims to assess the feasibility of simultaneously producing hydrogen and hypochlorous acid using a 2-compartment PEM water electrolysis cell with an installed membrane electrode assembly (MEA).Methods : External power was applied to the PEM water electrolysis device through a potentiostat to induce the electrolysis reaction and to confirm the production of hydrogen and hypochlorite simultaneously. Linear Sweep Voltammetry (LSV) experiments were conducted, thereby determined the minimum voltage required for the electrolysis. Constant current experiments were performed by applying a fixed current of 1 A for 1 hour, measuring voltage changes every second to evaluate the stability and efficiency of hydrogen production. The hydrogen production rate was measured using a mass flow meter, while the hypochlorite production was determined using a portable free chlorine photometer.Results and Discussion : In this study, the minimum voltage required for hydrogen generation in a PEM water electrolysis cell was investigated using LSV with Deionized (DI) water. The results showed that the current increased from around 1.4 V, indicating an approximate voltage efficiency of 82%. NaCl was introduced to the anode in the PEM electrolysis cell to induce electrochemical reactions. When the anolyte was NaCl, the voltage was observed to increase by 0.77 V compared to using DI water. Optimization experiments were conducted to investigate the influence of electrolyte concentration and flow rate on hypochlorite and hydrogen production. As the electrolyte concentration increased, the hypochlorite generation also increased, with a maximum of 104±0.50 mg/L observed with NaCl 10 g/L. Additionally, when the flow rate was reduced, the hypochlorite production increased, and at a reduced flow rate of 5 mL/min compared to 20 mL/min, hypochlorite generation increased by 127.3%. However, the hydrogen production showed no significant variation with NaCl concentration or flow rate.Conclusion : This study explores a novel approach using PEM water electrolysis technology to simultaneously produce hydrogen and chlorinated disinfectants. The research employed a PEM electrolysis cell with the MEA to generate both chlorine-based compounds and hydrogen. By varying the concentration and flow rate of the anolyte, the production efficiencies of hypochlorite were compared. This system showed that PEM electrolysis can be a promising alternative for disinfection and energy production in terms of environmental protection and cost-effectiveness.