Coupled transport of Ag(I) ions through triethanolamine–cyclohexanone-based supported liquid membranes

Abstract

Facilitated transport of silver(I) ions in acidic medium, across a supported liquid membrane (SLM) by using triethanolamine (TEA) as carrier, dissolved in cyclohexanone, has been investigated. The parameters studied are HNO 3 concentration variation in the feed, pH of the feed solution, carrier concentration in the membrane phase, silver(I) ions concentration in the feed phase and KCN concentration in the stripping phase. Increase in H + concentration by increasing HNO 3 concentration from 0.5 to 1 M results into an increase in silver ions flux but a decrease in flux has been found beyond 1 M HNO 3 concentration in the feed, providing a maximum flux of 3.21 × 10 −7 mol/m 2 s at 1 M HNO 3. Increase in TEA concentration inside the membrane enhances flux with its maximum value at 2.25 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 Ag(I) ions transport are 1 M HNO 3 (feed), 2.25 M TEA (membrane) and 1.5 M KCN in the stripping phase. It has been observed that Ag(I) flux across the membrane tends to increase with increase in Ag(I) ions concentration in the feed phase. Applying the studied conditions to silver plating waste solutions, Ag ions have been removed up to 99% in a time interval of 5 h.