Abstract
The cementation of cadmium ions from aqueous solutions on zinc powder was studied as a function of solution pH and temperature, amount of zinc, concentration of cadmium ion, contact time, and the addition of several organic compounds, including surfactant and chelating agent. Cementation of cadmium was shown to be a feasible treatment process to achieve a high degree of cadmium removal within a fairly reasonable contact time. The deposition of cadmium and zinc consumption are highly dependent on solution pH conditions and is most practically operated at weak acidic conditions of pH 4–5. The reaction rate is approximately first order with respect to both the amount of zinc and the concentration of cadmium ion. Among the surfactants used in this study, only the presence of sodium dodecyl sulfonate, an anionic surfactant, noticeably enhanced the cementation rate of cadmium by zinc powder. The presence of ethylene-diaminetetraacetic acid (EDTA) in aqueous solutions inhibited the removal of cadmium by zinc due to the possible formation of Cd–EDTA chelates, which possess higher redox potential than that of free cadmium ions.
Published Version
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