title: Three-phase extraction study of cyanex 923-n-heptane/H(2)SO(4) system.
abstract: Phase behavior of the extraction system, Cyanex 923-heptane/H(2)SO(4)-H(2)O has been studied. The third phase appeared at different aqueous H(2)SO(4) concentration with varying initial Cyanex 923 concentration and temperature affects its appearance. Almost all of H(2)SO(4) and H(2)O are extracted into the middle phase. The H(2)SO(4) concentration in the third phase increases with the increasing aqueous acid concentration (C(H(2)SO(4),b)) while the water content first increases and then reaches a constant value at C(H(2)SO(4),b)=11.3 mol l(-1). In the region of C(H(2)SO(4),b) higher than 5.2 mol l(-1), the composition of the middle phase is only related to the equilibrium concentration of H(2)SO(4) in the bottom phase. H(2)SO(4) and H(2)O are transferred into the middle phase mainly by their coordination with Cyanex 923 when C(H(2)SO(4),b) is less than 11.3 mol l(-1). When C(H(2)SO(4),b) is higher than 11.3 mol l(-1), excess H(2)SO(4) is solubilized into the polar layer of the aggregates. In the region considered, the extracted complex changes from C923 . H(2)SO(4) to C923 . H(2)SO(4) . H(2)O and then to C923 . (H(2)SO(4))(2) . H(2)O.
authors.affiliation: Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry (CIAC), Chinese Academy of Sciences, Changchun 130022, People's Republic of China.
authors.forename: Wuping
authors.initials: W
authors.lastname: Liao
authors.forename: Qingkun
authors.initials: Q
authors.lastname: Shang
authors.forename: Guihong
authors.initials: G
authors.lastname: Yu
authors.forename: Deqian
authors.initials: D
authors.lastname: Li