Electrodeposition of Calcium Carbonate and Magnesium Carbonate from Hard Water on Stainless-Steel Electrode to Prevent Natural Scaling Phenomenon

Abstract

This study focuses on preventing scale formation in hard waters by controlled electrode-position of Ca2+ and Mg2+ on a stainless-steel cathode at constant applied current intensity. The influence of the anode material, BDD or Ti/Pt/PbO2, cathode active area, stirring speed, and applied anodic current intensity on the inorganic carbon (IC), Ca2+, and Mg2+ removal was investigated. Assays were performed with model hard water solutions, simulating Bounouara (Algeria) water. The scaling inhibiting properties of the treated water were followed by measuring IC, calcium, and magnesium concentrations and chronoamperometric characterization of the treated solutions. The influence of the Ca/Mg molar ratio on the inorganic carbon removal by electrolysis was also evaluated, utilizing model solutions with different compositions. It was found that an increase in stirring speed or cathode geometric area favors IC and Ca2+ and Mg2+ removal rates. The applied current intensity was varied from 0.025 to 0.5 A, and the best results were obtained for 0.1 A, either in IC and Ca2+ and Mg2+ removals or by the accelerated scaling tests. However, energy costs increase with applied current. The deposit formed over the cathode does not seem to influence posterior deposition rate, and after eight consecutive assays, the solid deposition rate was kept constant. Ca/Mg ratio influences IC removal rate that increases with it. The results showed that hard-water scaling phenomena can be prevented by solid electrodeposition on the cathode at applied constant current.

Electrochemical applications in RAS: A review

“…The pH at the cathode vicinity is typically pH > 10 55,110,111 and may result in deposition of calcium, magnesium, phosphate, and carbonate salts, on the electrode surface. While some applications suggest utilizing this feature, for example, for electrochemical water softening, 112,113 for chlorine production applications the accumulation of a thick layer of scale changes the available cathode area thereby affecting the actual current density, increases the required potential to maintain a constant current, and even leads to electrolyzer clogging. There are several cleaning methods that are used in the practice, among them chemical cleaning by periodically dissolving the scale with a strong acid or a periodic reversal of the electrodes' polarity.…”

Low-Temperature Electrochemical Cement Clinker Production

“…29−31 Furthermore, various approaches have been explored to hinder the formation of scale deposits on electrodes, primarily composed of calcium carbonate. 32 These approaches include periodic alteration of electrode polarity to induce pH swings, 33 utilization of electromagnetic fields, 33 and promotion of turbulent conditions as strategies to mitigate scaling formation. 34 The high capital cost for the development and construction of cement electrolyzers is another significant challenge.…”

“…To address this challenge, deposit-resistant membranes and electrodes are required. Progress has previously been demonstrated in electrodialysis and water treatment contexts to prevent deposits on membranes, where chemical, mechanical, and electrochemical techniques have been used to modify ion-exchange membranes. − Furthermore, various approaches have been explored to hinder the formation of scale deposits on electrodes, primarily composed of calcium carbonate . These approaches include periodic alteration of electrode polarity to induce pH swings, utilization of electromagnetic fields, and promotion of turbulent conditions as strategies to mitigate scaling formation …”