Triethanolamine–cyclohexanone supported liquid membranes study for extraction and removal of nickel ions from nickel plating wastes

Abstract

The permeation of Ni(II) from its aqueous solution through a supported liquid membrane containing triethanolamine (TEA) dissolved as mobile carrier in cyclohexanone has been studied. The effects of Ni(II) ion, HCl (in feed) and TEA (in membrane) concentrations have been studied. Ni(II) ions concentration increase in the feed leads to an increase in flux from 6.28 × 10 −9 to 22.52 × 10 −9 mol/m 2 s within the Ni(II) ions concentration range (8.43–29.47) × 10 −4 mol/dm 3 at 2 M HCl in the feed and 3.00 M TEA in the membrane. Increase in H + concentration by increasing HCl concentration from 0.1 to 2 M results into an increase in nickel ions flux but a decrease in flux has been found beyond 2 M HCl concentration in the feed, providing a maximum flux of 11.67 × 10 −9 mol/m 2 s at 2 M HCl. Increase in TEA concentration in the liquid inside the membrane enhances flux with its maximum value at 3.00 M TEA. Further increase in the concentration of TEA leads to a decreased rate of transport due to the increase in viscosity of membrane liquid. The optimum conditions for Ni(II) ions transport are, 2 M HCl (feed) and 3.00 M TEA (membrane). It has been observed that Ni(II) flux across the membrane tends to increase with these ions concentration increase. Applying the studied conditions to Ni plating waste solutions indicated more than 99% removal of Ni ions. Similar transport for EDTA-complexed Ni anions was observed across TEA–cyclohexanone based SLM, indicating a Ni anion transport, coupled with protons and chloride or EDTA co-ions.