Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan; Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito, Ibaraki 310-8521, Japan.
Talanta. 2003 May 1;59(6):1189-98. doi: 10.1016/S0039-9140(03)00031-6.
The distribution ratio (D(M)) of Pd(II) by the extraction with 2-methyl-8-quinolinol (HMQ) was determined using the supercritical carbon dioxide medium (SF-CO(2)) and organic solvent media such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From experimental results of the slopes of logD(M) versus pH plot and logD(M) versus HMQ concentration plot, the extracted species both in the SF-CO(2) extraction (SFE) and the solvent extraction (SE) were determined to be Pd(MQ)(2). The distribution constant of HMQ (K(D,HMQ)) in the SFE and SE systems were determined from the dependence of the distribution ratio of HMQ (D(HMQ)) on the pH. A linear relationship was observed between logK(D,HMQ) and the solubility parameter (delta) of the extraction medium based on the regular solution theory in both the SFE using SF-CO(2) at the pressure of 8.5-40 MPa and the SE systems. The difference in the slope of the logK(D,HMQ) versus delta plot between the SFE and the SE systems is attributable to the extent of the specific interaction of the solute HMQ with the solvent molecules, i.e. CO(2) molecules and the organic solvent molecules. The D(M) versus delta plot obtained under a given extraction condition using SF-CO(2) (11-40 MPa) and organic solvents showed clear linearity. The D(M) obtained using SF-CO(2) at relatively low pressure range from 8.5 to 11 MPa was independent of the pressure and the delta of SF-CO(2), which coincides with the experimental fact that the solubility of Pd(MQ)(2) in the SF-CO(2) at 8.5-11 MPa was practically constant.
采用超临界二氧化碳介质（SF-CO2）和有机溶剂（如全氟甲基环已烷、庚烷、环己烷、四氯化碳和苯）研究了 2-甲基-8-喹啉醇（HMQ）萃取钯（II）的分配比（D（M））。根据 logD（M）与 pH 关系图和 logD（M）与 HMQ 浓度关系图的斜率实验结果，确定了在 SF-CO2 萃取（SFE）和溶剂萃取（SE）中萃取物种均为 Pd（MQ）（2）。从 SFE 和 SE 体系中 HMQ 的分配常数（K（DHMQ））取决于 HMQ 的分配比（D（HMQ））对 pH 的依赖性来确定。基于正则溶液理论，在 8.5-40 MPa 压力下使用 SF-CO2 的 SFE 和 SE 体系中，均观察到 logK（DHMQ）与萃取介质溶解度参数（δ）之间存在线性关系。SFE 和 SE 体系中 logK（DHMQ）与 δ 关系图斜率的差异归因于溶质 HMQ 与溶剂分子（即 CO2 分子和有机溶剂分子）的特定相互作用的程度。在给定的萃取条件下，使用 SF-CO2（11-40 MPa）和有机溶剂得到的 D（M）与 δ 关系图显示出明显的线性关系。在 8.5-11 MPa 的相对较低压力范围内使用 SF-CO2 获得的 D（M）与压力和 SF-CO2 的 δ 无关，这与 Pd（MQ）（2）在 8.5-11 MPa 的 SF-CO2 中的溶解度实际上保持恒定的实验事实相符。
