Kinetic Modelling of Electrokinetic Separation of Sulfate and Hydrogen Ions from Acidic Hot Spring Discharges

Abstract

Electrokinetic separation has been widely utilized to remove ionic compounds from wastewaters due to its high energy-efficient feature. Hot spring dischages usually contain abundant amounts of sulfate and chloride with a strong acidity, e.g., the pH value is around 1.6. In this study, two stacks with different configurations of electrokinetic separation processes were designed and used to remove SO4 -2 and H+ from hot spring discharges. The results indicated that, with an applied voltage of 10 V for 60 min, the removal ratios of sulfate, chloride, and hydrogen ions were 99%, 98% and 98%, respectively. The kinetic models were established to evaluate and predict the performance of SO4-2 and H+ separation under different operating conditions using the developed electrokinetic processes. The kinetic rate constants of various applied voltages (ranged from 2.9 to 17.0 V) using electrokinetic separation were determined accordingly. The mechanisms of different configuration designs for ions removal using electrokinetic stacks were also elucidated. The obtained paramters of kinetics could be used for reactor designs, cost evaluation and performance improvement in large-scale demonstrations. It was thus concluded that the developed electrokinetic separation processes could be a potential solution to the acidic wastewater discharges with an significant amount of dissolved solids.