“…As mentioned earlier, HOBO exists not only as a monomeric species but also as a dimeric species in nonpolar diluents. 7 Of these, only the monomeric species is interfacially active 7 and takes part in the complex formation at the interface. Consequently, the initial extraction rate did not correlate with the total concentration but with the monomeric HOBO concentration as shown in Figure 5.…”
Section: Resultsmentioning
confidence: 99%
“…(v) Extraction Rate. The extraction rate was measured using a stirred transfer cell . The aqueous and organic phases were stirred independently by two-blade stirrers in opposite directions with equal rotating speeds of 120 rpm, except for the measurement of the effect of stirring speed on the extraction rate.…”
Section: Methodsmentioning
confidence: 99%
“…The extraction rate was measured using a stirred transfer cell. 7 The aqueous and organic phases were stirred independently by twoblade stirrers in opposite directions with equal rotating speeds of 120 rpm, except for the measurement of the effect of stirring speed on the extraction rate. After introducing each phase into the cell, a small sample was taken at intervals from the organic phase, from which copper was stripped out with 2 M sulfuric acid to determine the copper concentration by atomic absorption analysis.…”
2-Hydroxy-4-n-octyloxybenzophenone oxime (HOBO) was recently synthesized to develop a
selective extractant for copper(II). HOBO exhibited a high selectivity for only copper(II) over
other base metals such as nickel(II) and cobalt(II) which are typically extracted with LIX series
hydroxyoxime reagents in the high pH region from 1 M aqueous ammonium nitrate solution.
This is due to the introduction of an alkoxyl group to the phenyl group of hydroxyoximes, which
causes a lowering of the dissociation constant of phenol. Copper(II) was extracted as a 1:2 complex
with HOBO (=
) according to the following reaction: Cu2+ + 2
⇔
+ 2H +; K
ex. The
extraction equilibrium constant, K
ex = 1.1 × 10-1, was obtained at 303 K. The extraction rate of
copper(II) was measured using a Lewis-type transfer cell at 303 K. The extraction reaction of
copper(II) with HOBO is interpreted as an interfacial reaction where the elementary reaction
step between the intermediate complex adsorbed at the interface and free extractant in the
aqueous phase is rate-determining. The reason this step is rate-determining was inferred.
“…As mentioned earlier, HOBO exists not only as a monomeric species but also as a dimeric species in nonpolar diluents. 7 Of these, only the monomeric species is interfacially active 7 and takes part in the complex formation at the interface. Consequently, the initial extraction rate did not correlate with the total concentration but with the monomeric HOBO concentration as shown in Figure 5.…”
Section: Resultsmentioning
confidence: 99%
“…(v) Extraction Rate. The extraction rate was measured using a stirred transfer cell . The aqueous and organic phases were stirred independently by two-blade stirrers in opposite directions with equal rotating speeds of 120 rpm, except for the measurement of the effect of stirring speed on the extraction rate.…”
Section: Methodsmentioning
confidence: 99%
“…The extraction rate was measured using a stirred transfer cell. 7 The aqueous and organic phases were stirred independently by twoblade stirrers in opposite directions with equal rotating speeds of 120 rpm, except for the measurement of the effect of stirring speed on the extraction rate. After introducing each phase into the cell, a small sample was taken at intervals from the organic phase, from which copper was stripped out with 2 M sulfuric acid to determine the copper concentration by atomic absorption analysis.…”
2-Hydroxy-4-n-octyloxybenzophenone oxime (HOBO) was recently synthesized to develop a
selective extractant for copper(II). HOBO exhibited a high selectivity for only copper(II) over
other base metals such as nickel(II) and cobalt(II) which are typically extracted with LIX series
hydroxyoxime reagents in the high pH region from 1 M aqueous ammonium nitrate solution.
This is due to the introduction of an alkoxyl group to the phenyl group of hydroxyoximes, which
causes a lowering of the dissociation constant of phenol. Copper(II) was extracted as a 1:2 complex
with HOBO (=
) according to the following reaction: Cu2+ + 2
⇔
+ 2H +; K
ex. The
extraction equilibrium constant, K
ex = 1.1 × 10-1, was obtained at 303 K. The extraction rate of
copper(II) was measured using a Lewis-type transfer cell at 303 K. The extraction reaction of
copper(II) with HOBO is interpreted as an interfacial reaction where the elementary reaction
step between the intermediate complex adsorbed at the interface and free extractant in the
aqueous phase is rate-determining. The reason this step is rate-determining was inferred.
“…It will also extract copper(II), cobalt(II), palladium(II), and zinc(II) under the appropriate conditions. Previous studies have shown that the complexation of nickel(II) with HNAPO is an interfacial reaction, − and is therefore a suitable system for observing the effect of interfacial physicochemical properties on extraction reaction rates. 1 Molecular structure of HNAPO.…”
The initial reaction rates of the extraction of nickel(II) by 2-hydroxy-5-nonylacetophenone oxime (HNAPO) in a two-phase oil/water system was measured using a total internal reflectance static transfer cell. A two-step reaction mechanism between nickel(II) and HNAPO was found to satisfactorily explain the observed initial reaction rate (R(int)). The addition of neutral surfactants, nonionic octaethylene glycol mono-n-dodecyl ether and zwitterionic n-dodecyldimethyl-3-ammonio-1-propanesulfonate, decreased R(int), which could be accounted for with a competitive surface adsorption model. The presence of the anionic surfactant sodium dodecyl sulfate accelerated and then decelerated R(int), while the cationic surfactant dodecyltrimethylammonium chloride caused a decrease. The effects of these charged surfactants were accounted for using a combination of a competitive surface adsorption model and the Boltzmann distribution of charged species.
“…Recently, we have investigated the solvent extraction of palladium(II) from aqueous chloride media with several kinds of extracting reagents, such as sulfur-containing extractants (Baba and Inoue, 1988) and a hydroxy oxime (Inoue et al, 1985). From these studies, it was found that extraction mechanisms were significantly affected by the interfacial activities of the extracting reagents as well as by their aqueous solubilities.…”
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