LAUSR

Abstract Two kinetic models, i.e., schemes, surface adsorbed nitrogen as divergent (SND) and surface adsorbed NO as divergent (SNOD) towards NH4+ and N2 production, were developed to model simultaneous electrochemical reduction of the nitrate ion (NO3−) and oxidation of by-products. Experimental data for electrochemical reduction was collected in synthetic nitrate solution and actual wastewater using Al and Ti/RuO2 as cathode and anode, respectively. Sum of square errors (SSE) and Akaike's information criterion (AIC) analysis showed that the SND model well-represented all the concentration profiles of nitrogen species with the variation in all the operating parameters. Desorption of nitrite ion from the cathode surface was the rate-determining step for the SND kinetic model. Mechanistic and kinetic analysis suggested that N2 gas was the main product. However, NO2− gets formed as the by-product in the alkaline environment, whereas, NO2− and NH4+ were the by-products in the acidic environment.