TY - JOUR
T1 - Spectral studies and equilibrium analysis of the didodecylnaphthalene sulfonic acid, dicyclohexano-18-crown-6, Sr2+ extraction system
AU - Bryan, S. A.
AU - McDowell, W. J.
AU - Moyer, B. A.
AU - Baes, C. F.
AU - Case, G. N.
PY - 1987/8/1
Y1 - 1987/8/1
N2 - The species and equilibria present in the synergistic extraction system for strontium, composed of didodecylnaphthalene sulfonic acid (HDDNS) and dicyclohexano-18-crown-6 (DC18C6) in CCI4, have been studied by IR and proton NMR spectroscopies, vapor pressure osmometry (VPO), and Karl Fischer (KF) titrations. With the aid of least-squares computer methods to fit the IR and VPO results, a series of proposed equilibria and associated equilibrium constants have been shown to adequately account for all of the observed behavior. The sulfonic acid and the salt of the acid alone in CCI4 solution form the micellar species (HDDNS. xH20)11(x is in the range 7–8) and (Sr(DDNS)2.11 H20)6 respectively. The sulfonic acid alone, under conditions of intermediate loadings with Sr2+, yields the predominant species (Sr(DDNS)2)3(HDDNS)5.xH2O. When alone in solution, DC18C6 is a monomer, but it forms adducts with the free sulfonic acid and its strontium salt, yielding the respective product species (HDDNS)7•DC18C6•xH2O and Sr(DC18C6) (DDNS)2.•2H2O. An excess of HDDNS or Sr(DDNS)2 in the presence of Sr(DC18C6)(DDNS)2•2H2O yields predominantly Sr(DC18C6)(DDNS)2(HDDNS)2•xH2O and (Sr(DC18C6)(DDNS)2)2(Sr(DDNS)2)3•.xH2O respectively.
AB - The species and equilibria present in the synergistic extraction system for strontium, composed of didodecylnaphthalene sulfonic acid (HDDNS) and dicyclohexano-18-crown-6 (DC18C6) in CCI4, have been studied by IR and proton NMR spectroscopies, vapor pressure osmometry (VPO), and Karl Fischer (KF) titrations. With the aid of least-squares computer methods to fit the IR and VPO results, a series of proposed equilibria and associated equilibrium constants have been shown to adequately account for all of the observed behavior. The sulfonic acid and the salt of the acid alone in CCI4 solution form the micellar species (HDDNS. xH20)11(x is in the range 7–8) and (Sr(DDNS)2.11 H20)6 respectively. The sulfonic acid alone, under conditions of intermediate loadings with Sr2+, yields the predominant species (Sr(DDNS)2)3(HDDNS)5.xH2O. When alone in solution, DC18C6 is a monomer, but it forms adducts with the free sulfonic acid and its strontium salt, yielding the respective product species (HDDNS)7•DC18C6•xH2O and Sr(DC18C6) (DDNS)2.•2H2O. An excess of HDDNS or Sr(DDNS)2 in the presence of Sr(DC18C6)(DDNS)2•2H2O yields predominantly Sr(DC18C6)(DDNS)2(HDDNS)2•xH2O and (Sr(DC18C6)(DDNS)2)2(Sr(DDNS)2)3•.xH2O respectively.
UR - http://www.scopus.com/inward/record.url?scp=0023518126&partnerID=8YFLogxK
U2 - 10.1080/07366298708918590
DO - 10.1080/07366298708918590
M3 - Article
AN - SCOPUS:0023518126
SN - 0736-6299
VL - 5
SP - 717
EP - 738
JO - Solvent Extraction and Ion Exchange
JF - Solvent Extraction and Ion Exchange
IS - 4
ER -