Effect of additives and electrode roughness on the production of hypochlorite sanitizer by the electrolysis of NaCl solution in a batch recycle reactor

Abstract

The present work aims at studying the effect of some of the variables such as solution flow rate, electrode surface roughness, current density, NaCl concentration and the presence of additives such as drag reducing polymers and surfactants on the performance of an electrochemical reactor which produces sodium hypochlorite by the electrolysis of NaCl solution. A rectangular undivided cell with a graphite anode and Ni plated steel cathode was used to conduct the present study. The performance of the batch recycle reactor was assessed by determining: (i) hypochlorite yield (ii) cell current efficiency and (iii) electrical energy consumption in kW•h/kg. The results revealed that the energy consumption of hypochlorite production increases by increasing current density and solution flow rate while it decreases by increasing NaCl concentration and electrode surface roughness. Electrode roughness improved the performance of the cell and decreased the energy consumption by an amount ranging from 23 to 39% compared to the smooth electrode surface depending on the operating conditions. The presence of additives such as drag reducing polymers or surfactants were found have beneficial effects on the cell performance and decreases the electrical energy consumption especially with rough electrodes.