Odashima T, Endoh I, Ishii H
Chemical Research Institute of Non-Aqueous Solutions, Tohoku University, Katahira, Aoba-ku, Sendai, 980 Japan.
Talanta. 1990 Dec;37(12):1163-8. doi: 10.1016/0039-9140(90)80186-j.
The equilibria and kinetics of the solvent extraction of gallium(III) from aqueous monochloroacetic acid [HA] media with a benzene solution of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone [PMBP or HL] has been studied at 25 +/- 0.1 degrees and an ionic strength of 0.2. The species extracted was found to be GaL(3). The value of the acid dissociation constant of PMBP determined spectrophotometrically was 1.17 x 10(-4). The values of the partition coefficient of PMBP and the extraction constant of its gallium complex between an aqueous and a benzene phase were found to be 3.72 x 10(3) and 2.51 x 10(4), respectively. The rate of extraction was first-order with respect to the concentrations of gallium(III) in the aqueous phase and PMBP in the organic phase, inversely first- and second-order with respect to the hydrogen-ion concentration and zero- and first-order with respect to the concentration of monochloroacetate ions. Two mechanisms operate for this extraction, depending on the pH of the aqueous phase, one where the formation of the first complex, GaL(2+), between Ga(3+) and L(-) in the region of pH < 1.6 becomes the rate-determining step, and the other where the formation of the first complex between GaA(2+) and L(-) in the region of pH 2.0-2.3 is the rate-determining step. The rate constant for the first of these reactions was calculated to be 1.62 x 10(4)l.mole(-1).sec(-1), but that for the second could not be determined.
在25±0.1℃和离子强度为0.2的条件下，研究了用1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮[PMBP或HL]的苯溶液从一氯乙酸[HA]水介质中萃取镓(III)的平衡和动力学。发现萃取的物种为GaL(3)。用分光光度法测定的PMBP酸解离常数为1.17×10(-4)。发现PMBP在水相和苯相之间的分配系数以及其镓配合物的萃取常数分别为3.72×10(3)和2.51×10(4)。萃取速率对水相中镓(III)的浓度和有机相中PMBP的浓度为一级反应，对氢离子浓度为负一级和负二级反应，对一氯乙酸根离子浓度为零级和一级反应。根据水相的pH值，该萃取有两种机制起作用，一种是在pH<1.6的区域内，Ga(3+)和L(-)之间形成第一个配合物GaL(2+)成为速率决定步骤，另一种是在pH 2.0 - 2.3的区域内，GaA(2+)和L(-)之间形成第一个配合物是速率决定步骤。计算出第一个反应的速率常数为1.62×10(4)l·mol(-1)·s(-1)，但第二个反应的速率常数无法确定。
