The Electrosorption Behavior Of Carbon Composite Electrodes Towards Removal Of Calcium And Bromate From Water

This article uses the electrophoretic deposition method, which is simple operation and low cost, to prepare two different types of carbon composite electrodes:the CNTs/4A zeolite composite electrode and ACF/hydrotalcite composite electrodes. In this study, the surface structure characteristics and electrochemical properties of the electrodes were analyzed by means of scanning electron microscope (SEM) and electrochemical workstation, respectively. The CNTs/4A zeolite composite electrode were studied of electrosorption effect on calcium. The electrosorption properties were studied as a function of initial concentration, initial voltage, the proportion between CNTs and zeolite on the electrosorption process. The selectivity and regeneration capability of the electrode were also studied. The ACF/hydrotalcite composite electrodes were also studied of electrosorption effect on bromate, and the electrosorption properties were studied as a function of pH, initial voltage, bromate concentration. And at the same time electrosorption effect were compared with the acid modified ACF electrode and without any processing of ACF electrode. Experimental results show that the CNTs/4A zeolite composite electrode had remarkable calcium electrosorption ability of25mg/g at voltage2.0V, calcium ion initial concentration750mg/L, and the proportion between CNTs and zeolite1:4, respectively. At the same time, compared with magnesium and sodium, the composite electrode has a good selectivity for calcium. And by removing the electric field condition or to applying the opposite voltage, the composite electrode can regenerate, after six times recycling the composite electrode removal rate of Ca2+can reach60%. In the pH=7.0, the voltage of2.0V, bromate ions of the initial concentration of10mg/L, the ACF/hydrotalcite composite electrode for BrO4-removal efficiency can achive good effect at pH7.0, voltage2.0V and bromate ion initial concentration10mg/L. By comparing with the acid modified ACF electrode and untreated ACF electrode, the three different electrodes for bromate remove rate following the order:the ACF/hydrotalcite electrode> the acid modified ACF> the untreated ACF. Combining kinetic model analysis results show that pseudo second order models fit the experimental data very well for the CNTs/4A zeolite composite electrode, Fractal-Like adsorption kinetics model fit the experimental data for the ACF/hydrotalcite electrode very well.