Coalescence extraction of silver(I) using the temperature-induced phase separation (TIPS) process

The extraction of silver(l) from solutions by three dinitrile solvents has been investigated. The methodology is based on the temperature-induced phase separation (TIPS) of silver(l) with malononitrile (MN), succinonitrile (SCN), and glutaronitrile (GN) solvents in absence of chelating agent. Three dinitrile solvents MN, SCN, and GN are able to participate in coalescence extraction. Analysis silver(l) content in both organic and aqueous phases was accomplished by inductively coupled plasma (ICP) spectrophotometry. All three systems were highly efficient in extraction of silver (>98%) and extraction times were fast (few minutes). The quantitatively extraction efficiency is achieved because of formation of complexes of soft cation (silver) with dinitrile solvents. The selectivity of silver ion extraction from aqueous solutions containing alkali, alkaline earth (at Mn+/silver mole ratio of 100), transition and some heavy metal ions (at mole ratio of 5) was investigated and it was found that with the exception of Hg2+ and Cu2+ none of cations used interfered with the silver ion extraction. The proposed method has been applied to extraction and determination of silver in contaminated anodic sludge. The extraction efficiency for three replicates after 2 min was 98% with R.S.D. = 1.1 %. (C) 2004 Elsevier B.V All rights reserved.