衍生-超临界流体萃取金属离子的技术与进展

综述了近年来衍生-超临界流体萃取环境样品和环境模拟样品中金属离子的研究报道,结合作者的研究工作,着重评述了超临界流体萃取不同环境样品、环境模拟样品中金属离子的原理、萃取过程的动力学模型、衍生剂的选择原则、金属螫合物在超临界流体中的溶解度理论、影响萃取效率的因素、金属离子超临界流体萃取应用研究现状与进展等。利用流体与基体改性技术实现了金属离子和金属螯合物的超临界流体萃取,且在萃取体系中加入适量的表面活性剂能显著提高萃取效率。     

白术挥发性成分的超临界流体萃取及其分析

采用超临界流体萃取白术挥发油成分,对萃取条件进行优化,并用气相色谱、气相色谱－质谱分析鉴定出超临界流体萃了的挥发油中22个化合物。最佳的超临界流体萃取条件为压力22.0MPa,温度60℃,0.5mL乙醇作改性,先静态萃取10min(CO2用量2.0mL),再动态萃取40min(CO2流速为0.3mL/min)。将超临界流体萃取与水蒸气蒸馏进行对比,水蒸气蒸馏5h的油收率仅为超临界流体萃取1h油收率的10.32%,证明超临界流体萃取替代传统萃取的必要性。     

超临界流体技术在萃取中的应用简介

超临界流体萃取技术具有许多传统技术所没有的快速、高效、高选择性、低能耗等优点，特别是超临界流体的特性是它可以代替高毒有机溶剂做反应介质，符合绿色化学的要求。本文综述了超临界流体的特性，介绍了超临界流体萃取的原理，归纳了超临界流体萃取的应用现状，并介绍了超临界流体的其他领域应用概况。     

环境模拟样品中多环芳烃的超临界流体萃取I．利用正交设计选择最佳萃取条件

采用正交设计实验方法，研究了从环境模拟样品中超临界流体萃取（ＳＦＥ）多环芳烃（ＰＡＨ）的最佳萃取条件。着重考察了超临界流体的压力、温度和用量等对萃取效率的影响。结果表明，压力的影响居第一位，温度影响次之，超临界ＣＯ２的用量的影响居第三位。建立了选择超临界流体萃取条件的简单方法     

络合剂在超临界CO_2络合萃取重金属离子中的研究进展

本文综述了络合剂在超临界CO2萃取重金属离子中的应用状况,分析并概括了不同类型络合剂在超临界CO2萃取重金属离子应用中的萃取范围、萃取效果以及优缺点,最后对络合剂的发展前景进行了展望。     

环境模拟样品中多环芳烃的超临界流体萃取：Ⅰ.利用正交设…

采用正交设计实验方法，研究了从环境模拟样品中超临界流体萃取多环芳烃的最佳萃取条件。着重考察了超临界流体的压力、温度和用量等对萃取效率的影响。     

醌类化合物的超临界流体萃取研究进展

综述了国内近20年来超临界流体萃取技术应用于醌类化合物分离的研究进展,重点介绍了超临界流体萃取技术在中草药中醌类化合物的分析测定方面的应用,分析了影响醌类成分提取效果的主要因素,优化萃取温度和萃取压力能够改善琨类化合物的分离效果,夹带剂的使用则有效地提高了超临界流体的萃取能力。     

超临界流体萃取分离离子液体与有机物及其相平衡的研究

离子液体具有一些优良的物理和化学性质,非常有希望成为传统有机溶剂的替代溶剂.但是如何从过程物流中分离和回收离子液体将是其工业化应用的一个很大挑战.蒸馏、液液萃取和超临界萃取是目前已知的三个可行的方法.其中超临界萃取可应用于离子液体与挥发的或相对不挥发的有机物的分离,而且不存在相间交叉污染.本文从二元体系相平衡、三元体系相平衡、模型化研究和萃取实验结果方面介绍了超临界萃取方法的最新研究进展,在此基础上提出了用超临界丙烷替代超临界二氧化碳作为萃取溶剂的新思路,并探讨了该领域今后的研究方向和工业化前景.     

金属离子的超临界流体萃取技术的进展

超临界流体萃取技术在分离方面发展迅速,应用前景十分广泛。文中综述了超临界流体技术的萃取机理及对金属离子萃取的研究。     

超临界萃取装置的研制及其应用

超临界流体萃取是近的上来兴起的一种新的分离技术，报道了将超临界萃取原理与回流技术相结合研制的二氧化碳回流中低压超临界流体萃取设备，解决了关键实验手段，通过应用证明设备可靠，费用低廉，有实用价值。     

二(2,4,4-三甲基戊基)膦酸在中空纤维膜器中萃取镱、铒及传质研究

中空纤维膜萃取技术是将液液萃取过程与膜过程相结合的新型分离技术．二（２,４,４三甲基戊基）膦酸（ＨＢＴＭＰＰ,ＨＬ）萃取稀土及其它高价金属离子时所需水相酸度低,反萃容易,加之空间位阻等因素,很可能成为优于２乙基己基膦酸单２乙基己基酯（ＨＥＨ／...     

膜基萃取中钕、钐的传质及界面反应动力学

采用自制聚偏氟乙烯中空纤维膜吕,在HEH／EHP煤油体系不,对钕,钐的萃取及界面反应进行了研究。结果表明,膜器中的萃取反应与液－液萃取相同,可视为准一级反应。考察了料液酸度,萃取剂浓度,钕,钐离子浓度与萃取速率的关系,获得了相应的反应级数,根据界面反应动力学,得到了动力学方程,速率常数及钕,钐的分离系数。     

Solvent extraction of europium from nitric acid solutions into chlorobenzene in the presence of calixarenes and dicarbollides

Several calixarenes were tested with the aim to find a synergic solvent extraction system with dicarbollide suitable for the extraction of europium from nitric acidic solutions. The best results were obtained with C₅₆H₇₂O₁₂S₄ and chlorobenzene. Data on the selectivity and interferences by other nitrates are given. The effect of the concentrations of the extractants and aqueous nitric acid was investigated. Basic data on the kinetics of the extraction reaction are presented. Attempts are described to transform this extraction reaction into an adsorption chromatographic arrangement.     

邻氨基酚萃取催化光度法测定痕量钒及其催化反应机理

研究了在ｐＨ３．５的弱酸性介质中，痕量钒（Ｖ）能催化溴酸钾氧化邻氨基酚的指示反应，用萃取平衡控制反应时间和水相中邻氨基酚的浓度及反应程度，通过测量４２４ｎｍ下有机相的吸光度，建立了萃取催化光度法测定钒的新方法，方法的线性范围为０．００１０～０．３０ｍｇ／Ｌ检出限为１．０×１０＾－６ｇ／Ｌ用于人发，煤和岩石中痕量钒的测定，结果满意，此外，还探讨了反应机理，建立了动力方程。     

Mechanism of uranium(IV) extraction with CYANEX 302 in kerosene from nitrate medium

The extraction of U(IV) by bis(2,4,4-trimethylpentyl) monothiophosphinic acid (CYANEX 302) in kerosene from nitric acid solution has been investigated under equilibrium conditions. The effects of the different parameters affecting the extraction process were studied and the stoichiometry of the extracted species was elucidated. The kinetics of this extraction was also investigated using a stirred Lewis cell. The effects of the different parameters affecting the extraction rate as well as the temperature were separately investigated. The results are interpreted by a reaction mechanism where the extraction process of U(IV) is controlled by a chemical reaction at the interface rather than in the bulk phase.     

Overview on extraction kinetics of metal adducts

The present overview presents a brief survey on the liquid-liquid extraction mechanism of metal chelates and adducts, the different reported reaction models and the most common methods used to follow the kinetics of extraction process are given. The effect of the different phenomena affecting the extraction rate and the importance of the kinetic information in connection with technical processes and counter-current modelling are also discussed.     

手性化合物的萃取分离研究进展

综述手性化合物的萃取分离方法，包括亲合萃取分离、配位萃取分离、形成非对映体立体异构体萃取分离、离子交换反应萃取分离、反相胶团萃取分离以及膜萃取分离。中性氨基酸的萃取分离将会成为研究的热点。     

Spectrophotometric determination of total phenolics by solvent extraction and sorbent extraction optosensing using flow injection methodology

Flow injection analysis (FIA) procedures for the Spectrophotometric determination of phenol involving in-line concentration by solvent and sorbent extraction have been developed. The imine product formed in the reaction between phenol and 4-aminoantipyrine (4-AAP) is either extracted into chloroform (solvent extraction) or is temporarily retained on C₁₈-modified silica material contained in a microcolumn (sorbent extraction). In the latter case two variants of detection have been used namely the Spectrophotometric measurement of the methanolic eluent containing the concentrated dye and at-column optosensing of the retained reaction product followed by methanol elution to maintain reversibility of the process. In the solvent extraction procedure a 10-fold increase of sensitivity compared to the common FIA method without extraction is achieved but no corresponding improvement in detectability is observed. Under optimized conditions the detection limit amounts to 8 μg l⁻¹. Using sorbent extraction methodology, high concentration factors can be obtained when large sample volumes are used. The only limitation in getting correspondingly lower detection limits are an increasingly high and variable blank value with sampling volume. The detection limits obtained for measurement of the absorbance in the eluent and on-column optosensing are 11 μg l⁻¹ and 0.4 μg l⁻¹, respectively. A study of the extractability of various phenol derivates using both solvent and sorbent extraction revealed lower relative response rates compared to the FIA method without extraction. Phenolics that possess an additional acidic group are present in ionized form at the high pH of the assay and are not extractable at all.     

Problems of the speciation of chromium in soil samples

Different separation/detection methods (ion exchange, organic extraction, spectrophotometry) and four extraction media have been compared for the speciation of chromium. Due to the pH dependence of these methods only the spectrophotometric method using the diphenylcarbazide reaction has proved suitable for speciation analyses. If nitric acid is used for the initial extraction stage, problems are often encountered with the other method during subsequent speciation analysis. The reasons for this are discussed.     

Study on the extraction kinetics of phenolic compounds from petroleum refinery waste lye

A large amount of waste lye is produced in petroleum refineries during alkali cleaning process, which consists of high concentration of phenols, sulfides, oils and other pollutants. In this study, tributyl phosphate (TBP) was used as extraction agent and the extraction kinetics of phenolic compounds was investigated by the constant interfacial cell method. The effects of stirring speed, temperature and specific area on extraction rate were studied. The experimental results show that the extraction of phenols by TBP is a first-order reaction, and the extraction process may be controlled by diffusion. The effects of stirring speed and specific area on extraction rate are significant.