Co（Ⅱ） Sorption on Zinc Hexacyanoferrate

By batch sorption experiments, the effects of temperature, pH, contact time, initial Co²⁺ concentration on the sorption of Co（Ⅱ） on zinc ferrocyanide(KZnFC) prepared by co-precipitated method were investigated. The possibility of KZnFC reused was studied, too. The sorption process was analyzed by the thermodynamic and kinetic, and the sorption mechanism was characterized by TEM, ICP and XRD of KZnFC before and after Co（Ⅱ） sorption. The experimental results indicate that the sorption of Co（Ⅱ） on KZnFC is strongly dependent on pH and initial Co²⁺ concentration, the equilibrium sorption capacity Q_e can be up to 38.53 mg/g at temperature 25℃, pH=5.5 and t=300 min. KZnFC has better reuse ability after desoption with HCl solution and KCl solution. The sorption process is more consistent with the Langmuir sorption model and second order reaction kinetics model. The ICP and XRD analysis of KZnFC before and after adsorbing Co（Ⅱ） indicate that the Co（Ⅱ） sorption is mainly due to the ion exchange between K⁺ in KZnFC and Co²⁺ in the solution. The lattice constants of the sample have changed after the sample absorbed Co(Ⅱ) and have effected the preferred orientation of crystals.