Liu Shufen,Yang Shenghai,Wang Shuyue,Luo Tao,Chen Yongming
A novel ZPER process is proposed for Cd separation from Zn-Cd-bearing dust, where Cd was separated thoroughly from acidic leachate of the dust by zinc plate replacement with the assistance of a microcurrent, and a new reaction surface of the Zn plate could be exposed by electrodissolution, which allowed the replacement reaction to proceed continuously. First, the effects of anode current density, initial pH, and reaction temperature were investigated in detail for Zn-Cd sulfate mixed synthesis solution. Under optimum conditions, the removal ratio and residual concentration of Cd were more than 99.99%, and only 0.34 mg/L and 97.59% Cd was replaced into the anode Cd sponge, which consisted of rod-shaped and branch-like particles. The purity of the Cd sponge and the replacement mole ratio of Cd generation and Zn consumption (RMR-Zn-Cd) were 97.87% and only 1.05, respectively. Finally, similar results were obtained from a sulfuric acid leaching solution of Cd-Zn-bearing dust. The new process has the advantages of deep cadmium removal, low zinc consumption, and low production cost.
To address the problem of excessive Cd (II) content in selenium-rich soil and water in Enshi region, this experiment utilized ion imprinting for selective adsorption of cadmium, which made the separation of selenium and cadmium possible. A novel attapulgite-based Cd(II) ion-imprinted polymer (AF-IIP) was prepared with the surface imprinting technique, using magnetic attapulgite as the matrix and (3-mercaptopropyl) trimethoxysilane (MPS) as the functional monomer. SEM, XRD, VSM, FT-IR and EDS elemental analysis were performed to confirm the structural transformations and compositional changes of the materials during the preparation process. The optimal pH, optimal time, adsorption kinetics and adsorption isotherms during the adsorption of Cd (II) by ion-imprinted polymers were investigated. The experimental results showed that the optimum pH of the adsorption process was 6.0 and the maximum adsorption amount was 49.0 mg·g −1 . In the presence of competitive ions, the adsorption capacity of AF-IIP for Cd (II) is much larger than that of Se ions, indicating that AF-IIP has good selectivity. The adsorption reaction conformed to the Langmuir isotherm model and kinetic data were more suitable to be explained by pseudo-second-order model. Furthermore, XPS analysis confirmed that Cd(II) adsorption primarily occurs via interactions with thiol (-SH) groups. In addition, regeneration tests have shown that AF-IIP was reusable and stable.
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