engleski

Selective dissolution of copper oxalate using supported liquid membranes

A supported liquid membrane has been used to dissolve selectively copper oxalate from a suspension of copper, calcium and cadmium oxalate, which have low, similar solubilities. 2-Hydroxy-5-nonyl-acetophenone oxim (HX) dissolved in kerosine was used as a carrier for copper transport from the suspension to the stripping solution. A mathematical model of the copper permeation is presented. The model takes into account the dissolution kinetics of CuC_2O_4 x 1/2 H_2O, the diffusion of copper ions through an aqueous stagnant layer, the chemical reaction at the aqueous/membrane interface, and the diffusion of the CuX_2 complex in the membrane. The model fits the experimental data well with a unique parameter set, except for the transport from an acetate buffered system, for which a lower rate constant for the reaction at the membrane interface had to be assumed. In a separate set of experiments the dissolution of copper oxalate hemihydrate in water was found to be surface reaction controlled.

Supported liquid membranes; Suspension; Copper oxalate; Selective dissolution; 2-hydroxy-5-nonyl-acetophenone-oxime

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