关键词: 电吸附, 结垢, 酸化吹脱, 除盐

Abstract: The effect of scaling on electrosorption desalination was studied by using electrosorption technology to desalt feed water containing different concentrations of Ca2+ and high concentration bicarbonate (HCO3-). The experiments were carried out at three Ca2+ concentrations of 40, 144 and 350 mg/L, respectively. The results show that the desalination efficiency drops remarkably at higher Ca2+ concentrations. Analysis of changes of ion removal rate, ion desorption rate and initial working current reveals that the calcium carbonate scale formed in the electrosorption module is a result of the interaction between Ca2+ and HCO3-, which causes the decrease of electrical double layer capacitance of electrode material, and therefore affects the desalination effect. Calcium carbonate can be dissolved after using acidification-stripping as pretreatment to obtain HCO3- concentration of 100 mg/L, which results in the improvement of desalination of the module. The crystallization and dissolution mechanism of calcium carbonate in the module are also discussed based on HCO3- ion residue and pH change in the working effluent.

Key words: electrosorption, scaling, acidification-stripping, desalination