Transfer Of Copper Ions Research Articles

A role for ascorbic acid in copper transport

Scurvy-like symptoms have been seen in experimental copper deficiency. This forecasts a role for the vitamin in copper metabolism. Ascorbate has been known to antagonize the intestinal absorption of copper. More recent studies have characterized a postabsorption role for ascorbate in the transfer of copper ions into cells. The vitamin reacts directly or indirectly with ceruloplasmin, a serum copper protein, specifically labilizing the bound copper atoms and facilitating their cross-membrane transport. Ascorbate at physiological levels and above impedes the intracellular binding of copper to Cu,Zn superoxide dismutase. The mechanism is unclear but nonetheless suggests both positive and negative regulatory functions for ascorbate in copper metabolism.

Solvation of ions, part XXX. Thermodynamics of transfer of copper ions from water to solvent mixtures

Free energies and Walden products show that the Cu+ and Ag+ ions are specifically solvated by acetonitrile (AN), 2-hydroxycyanoethane (HAN), and by pyridine (Py) whereas Na+ is specifically solvated by water, in mixtures of these organics with water. The Cu2+ ion is specifically solvated by pyridine in pyridine-water mixtures, but by water in acetonitrile-water mixtures. Ion-solvent, coordinated solvent-bulk solvent, and solvent-solvent interactions produce large entropy losses in the order Cu+≫Ag+>Na+ for transfer of these ions from water to dilute acetonitrile-water. The metallurgically important oxidations of copper, silver, CuS and Cu2 with CuSO4 in water are strongly favored in an enthalpic and free energy sense by the addition of acetonitrile, but addition of acetonitrile also produces a large loss of entropy for the reactions.

The extraction of copper from dilute aqueous solutions using a liquid membrane process

A liquid surfactant membrane process is considered for the separation of copper ions from dilute aqueous solutions. The process is shown to work effectively, solutions ranging in concentrations from 2000 ppm copper as copper sulphate (typical of acid leach solutions) down to 100 ppm copper have been successfully processed. In the case of the very dilute solutions the copper concentration in the final raffinate can be taken down to less than 1 ppm in a single contact stage. The liquid membrane is made up of a chelating agent, in this work Shell SME 529, organic diluent and emulsifying agent. Factors influencing mass transfer, such as membrane composition, O/A ratio, pH of the aqueous feed solution and acid content of the strip solution, contacting condition etc., have been studied. Providing membrane breakdown is low the process can be represented as a pseudo first order rate process. It is shown that by using this form of facilitated transport transfer of copper ions against very adverse concentration gradients across the membrane can be achieved. Further pilot plant work is required to examine scale up features of this process. Compared with conventional solvent extraction the amount of solvent (reagent and diluent) required in the contacting stage(s) is very much reduced. In this work it is shown that successful extraction of copper can be achieved using over two orders of magnitude less solvent than with solvent extraction.