Extractive separation of metal ions with inorganic ligands such as halide ion into supercritical carbon dioxide

金属离子与卤离子等无机配体萃取分离成超临界二氧化碳

基本信息

批准号：
12640579
负责人：
OHASHI Kousaburo
金额：
$ 2.3万
依托单位：
IBARAKI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

A supercritical fluid extraction (SFE) by a supercritical fluid instead of a conventional organic solvent has recently been focused on the advanced method to remove the metal ions from aqueous solutions and solid materials. Among the supercritical fluids used in SFE, a carbon dioxide has been widely used because of its desirable properties, i.e. relatively low critical temperature and pressure, non-toxicity, non-flammability and high purity, although its solvating power is lower than those of organic solvents, such as chloroform.Extraction of most metal ions into supercritical fluid carbon dioxide (SF-CO_2), which is highly nonpolar as a solvent, from liquid and solid samples is difficult due to the requirement of charge neutralization of metal ions. The formation, however, of an uncharged complex enabled the extraction of metal ions into SF-CO_2, as well as a conventional solvent extraction. To select a suitable chelating extractants, therefore, is essential in the SF-CO_2 extraction.This work performed fundamental studies for the extraction of gallium(III) with 2-methyl-8-quinolinol (HMQ) and 2-methyl-5-butyloxymethyl-8-quinolinol (HMO_4Q) into supercritical fluid carbon dioxide from a weakly acidic solution. The distribution constants of HMO_4Q between aqueous and SF-CO_2 phases were determined at 45℃, 8.6-20.4 MPa and I = 0.1 M (H, Na)NO_3. At 45℃ and 15.3 MPa, gallium(III) was hardly extracted with HMQ into SF-CO_2, but was quantitatively extracted with HMO_4Q in the pH range of 2.20-2.84. The extraction constant, K_<ex-co2> ( [Ga(OH)(MO_4Q)_2]_<SF-CO_2>[H^+]^3[Ga^<3+>]^<-1> [HMO_4Q])^<-2>_<SF-CO2>), of gallium(III) with HMO_4Q was determined to be 10^<-2.6> at 45℃, 15.7 MPa and I = 0.1 M(H, Na)NO_3, which was 63 times larger than that in heptane at 45℃ and 0.10 MPa. It was also found that the addition of 3 ,5-dichlorophenol as a synergist enhanced the extractability of gallium(III) with HMO_4Q into SF-CO_2.

最近，通过超临界流体代替传统有机溶剂的超临界流体萃取（SFE）已成为从水溶液和固体材料中去除金属离子的先进方法。尽管其溶解能力低于氯仿等有机溶剂，但因其具有较低的临界温度和压力、无毒、不易燃、纯度高等特点而被广泛应用。由于金属离子需要电荷中和，因此将大多数金属离子从液体和固体样品中转化为高度非极性的超临界流体二氧化碳（SF-CO_2）是很困难的，然而，能够形成不带电的络合物。将金属离子萃取到SF-CO_2中，与常规溶剂萃取一样，因此，选择合适的螯合萃取剂在SF-CO_2萃取中至关重要。本工作对SF-CO_2的萃取进行了基础研究。镓(III)与2-甲基-8-羟基喹啉(HMQ)和2-甲基-5-丁氧基甲基-8-羟基喹啉(HMO_4Q)从弱酸性溶液转化为超临界流体二氧化碳HMO_4Q在水溶液和SF之间的分布常数。 -CO_2 相在 45℃、8.6-20.4 MPa、I = 0.1 M (H, Na)NO_3在45℃和15.3 MPa下，用HMQ很难将镓(III)萃取到SF-CO_2中，但在pH 2.20-2.84范围内用HMO_4Q进行定量萃取。（ [Ga(OH)(MO_4Q)_2]_<SF-CO_2>[H^+]^3[Ga^<3+>]^<-1> [HMO_4Q])^<-2>_<SF-CO2 >), 在 45℃、15.7 MPa 和 I = 0.1 M(H, Na)NO_3，在45℃和0.10 MPa下比庚烷大63倍。还发现，添加3,5-二氯苯酚作为增效剂增强了HMO_4Q对SF-CO_2中镓(III)的萃取率。。