Liquid ion exchange application for micro amount separation and determination of Ca(II) and Mg(II) as anions species with EDTA

Abstract

Extracted Mg(II) and Ca(II) each one alone after combined with EDTA (H3Y-) as (MgHY-) and (CaHY-) after preparing ion pair complexes according to liquid ion exchange method by using Cinchonine (CK) after changing to liquid ion exchanger HCK+;Cl- in HCl medium, spectrophotometric studies showed that the ion pair magnesium complex HCK+;MgHY- had a wave length for maximum absorbance of λmax=241nm, but the maximum absorbance for calcium HCK+;CaHY- was λmax=278nm to determine the remaining quantity of Mg(II), the Eriochrome black T method was used, but for Ca(II) the crown ether DB18C6 method was used as new spectrophotometric method. Limitations to the study include optimum conditions for extraction ions in this study show a need for 1M HCl for Mg(II) and 0.8M HCl for Ca(II), to be present 100µg for each ion, 0.08M EDTA for Mg(II) and 1.0M EDTA for Ca(II), 1×10-4 M CK, after shaking for 10 min. Thermodynamic study shows ΔHex=0.058kJmol-1,ΔGex =-47.28 kJmol-1, ΔSex=158.86J.mol-1 K-1 for Mg(II) and for Ca(II) was ΔHex=0.0892kJmol-1, ΔGex=-54.66 kJmol-1, ΔSex=180.69J.mol-1 K-1.