Effect of operational parameters and material properties on hardness removal efficiency by electrochemical technique

Abstract

Electrochemical water treatment technology can be used for hard water softening, but its removal efficiency and energy consumption problems hinder its application. The effects of electrolysis voltage and cathode materials on efficiency, energy consumption and scale crystal form of electrochemical water treatment technology were studied experimentally. The experimental results show that electrochemical water treatment can effectively remove more than 40% of the TDS (total dissolved solids) in the influent. The electrolysis voltage has a great influence on the removal rate of hardness ions. The optimum electrolytic voltage for the titanium plate cathode is 25 V. At this electrolytic voltage, the treatment capacity of the titanium plate cathode is 16% higher than that of the copper plate cathode, and the energy consumption is 16% lower than that of the copper plate. Titanium plates are more efficient than copper plates and consume less energy. The effects of electrochemical water treatment on the scale crystal form were investigated by SEM (scanning electron microscopy) and XRD (X-ray diffraction). Electrochemical water treatment increases the mass fraction of aragonite in the calcium carbonate scale and changed the microscopic surface structure of calcium carbonate scale. HIGHLIGHTS The descaling efficiency of titanium plate as a cathode is higher than that of copper plate.; The unit energy consumption of titanium plate is lower than that of copper plate.; The best efficiency reduces the TDS by more than 40%.; Electrochemical reaction makes the microstructure of calcium carbonate irregular.; The crystal type of CaCO3 will change from calcite to aragonite as the electrochemical reaction proceeds.;

Keywords

• caco3 scale
• cathode materials
• crystal composition
• electrochemical water treatment
• electrolysis voltage