Study on electrocoagulation parameters (current density, pH, and electrode distance) for removal of fluoride from groundwater

Abstract

Excess fluoride in drinking water leads to numerous skeletal fluorosis diseases, including fluorosis deformities in the hips, knees, and spine. Electrocoagulation (EC) is one of the most promising electrochemical technologies for the removal of heavy metals, organics, and inorganic anions. In this study, Visual MINTEQ simulation was carried out to investigate the speciation of inorganic ions under conditions of saturated carbonate as a function of pH. EC experiments were carried out to verify the feasibility of EC and EC with chemical adsorption onto Ca(OH)2 for the removal of high-concentration fluoride (190 mg/l) under various conditions of pH (pH 3–9), electrode distance (5–15 mm), and current density (3.0–12.0 mA/cm2). Based on the simulation results, optimal pH conditions were determined for the formation of Al and the coagulation removal of F. Experiments based on the EC results showed that the removal efficiency was increased in acidic conditions, whereas variations in current density and electrode distance did not significantly affect the removal of F. Chemical adsorption is known to increase the removal efficiency of EC in acidic conditions (pH 3). While the results showed that the removal efficiency of F− was approximately 99 %, no significant effect of current density was observed because high current density can cause the liberation of Al(OH)3 and incomplete reaction. Overall, EC with chemical adsorption was found to be an effective and competitive remediation technology when the optimal pH conditions were used.