Optimizing slightly acidic electrolyzed water (SAEW) production through experiments and gene expression programming

Abstract

Slightly acidic electrolyzed water (SAEW) was produced through hydrochloric acid (HCl) electrolysis in a lab-scale reactor equipped with titanium-coated anode and cathode, without a diaphragm. The effect of changes in the production parameters (voltage, feed water flow rate (FFR), acid flow rate (AFR), and acid concentration (AC) and feed water characteristics (pHf, temperature, organic matter (OM) content, and water hardness) on the SAEW properties was evaluated based on the available chlorine concentration (ACC), pH, and oxidation-reduction potential (ORP) of the final product. Moreover, a gene expression programming (GEP) model was developed using the experimental results as a predictive tool to optimize the process. The results indicated that variations in FFR, AC, AFR, and OM significantly affected the SAEW properties. In contrast, no substantial effect was observed by varying the feed water's temperature, pH, voltage, and hardness. Using tap water, the optimal conditions to produce SAEW were observed at an FFR of 6.5 L/min, pHf of 7.45, at 20 °C using 6% AC at an AFR of 9 mL/s with reactor operation at 3.8 V. The proposed GEP model showed an efficient correlation coefficient (CC) of 0.941 and 0.938, and coefficient of determination (R2) of 0.885 and 0.880, respectively, for the unseen testing data to predict the ACC and pH of the produced SAEW.