羧酸(-COOH)的络合萃取

Reactive Extraction of Carboxylic Acid (-COOH)

羧酸是带有羧基的有机化合物,是一类极性有机化合物.羧酸在日常生活和工业生产中应用越来越广泛,其重要性也越来越显著.为了减少资源的浪费和环境污染,实现可持续发展,探讨安全有效、经济实用、易于实现自动化的羧酸分离技术,是化学工作者的研究方向.络合萃取是基于可逆络合化学反应,来萃取分离极性有机物稀溶液的高效、高选择性、经济成本低、易于实现自动化的方法,对高纯物质制备和高浓度有机废水的处理具有广阔的应用前景.本文综述了2008年6月至2020年5月期间在国内外公开发表的络合萃取羧酸方面的文献;总结了一元羧酸(甲酸、乙酸、丙酸、丁酸、戊酸、己酸、一氯乙酸、二氯乙酸、羟基乙酸、3-羟基丙酸、乳酸、丙烯酸、甲基丙烯酸、乙醛酸、丙酮酸、α-亚麻酸)、二元羧酸(草酸、丙二酸、丁二酸、衣康酸、富马酸、苹果酸、酒石酸、己二酸、戊二酸、庚二酸)、多元羧酸(柠檬酸、丙烯三甲酸)、芳香族羧酸(苯甲酸、苯乙酸、羟基苯甲酸、原儿茶酸、没食子酸、2,3-二苯基丙酸)的萃取条件、萃取机理、萃取工艺,比较了其在不同萃取体系中的萃取效果;总结了离子液体萃取羧酸的状况及盐效应对络合萃取效果的影响.结果发现:羧酸和萃取剂的界面反应机制受有机相的极性影响,极性稀释剂的加入可有效提高萃取剂的萃取效率;盐效应对络合萃取效率有正影响,氯化钠等无机盐的加入,可使萃取有机物的成本下降;与传统络合萃取相比,离子液体"更绿色",使用疏水性离子液体萃取羧酸的效果优于其他离子液体.同时对络合萃取动力学的情况进行了归纳,从动力学的角度分析了萃取剂及萃取反应的工艺可行性.进一步分析发现:新型萃取剂与萃取工艺的研发、反萃取技术与萃取动力学的研究、盐效应对络合萃取的影响规律、络合萃取与其他技术(分离、氧化还原、催化、吸附等)的联合应用等将是作者今后努力的方向.

Carboxylic acid is an organic compound containing carboxyl group,which is a kind of polar organic compound.Carboxylic acids have been widely used in daily life and industrial production,and their importance is more and more significant.To reduce the waste of resources,protect the environment,and achieve the sustainable development of green chemistry,the separation technique for carboxylic acid with the characteristic of safe,efficient,low-cost,practical and easy to realize automation is the research direction of the chemists.Reactive extraction,based on the reversible complexation chemical reaction,is an efficient,highly selective,low-cost and easily automatic method for the separation of polar organics from dilute solutions.Reactive extraction has great prospects for the preparation of high purity substances and the treatment of wastewater with highly concentrated organics.This work reviews the literatures on the reactive extraction of carboxylic acids reported from June 2008 to May 2020.The discussions are mainly focused on the extraction conditions,extraction mechanism and extraction process of various carboxylic acids including monocarboxylic acids(formic acid,acetic acid,propionic acid,butyric acid,valeric acid,caproic acid,monochloroacetic acid,dichloroacetic acid,glycolic acid,3-hydroxypropionic acid,lactic acid,acrylic acid,methacrylic acid,glyoxylic acid,pyruvic acid andα-linolenic acid),dicarboxylic acids(oxalic acid,malonic acid,butane diacid,itaconic acid,fumaric acid,malic acid,tartaric acid,adipic acid,glutaric acid and pimelic acid),polycarboxylic acid(citric acid and propylene tricarboxylic acid),aromatic carboxylic acid(benzoic acid,benzene acetic acid,hydroxybenzoic acid,protocatechuic acid,gallic acid and 2,3-diphenylpropionic acid).In addition,the extraction effects for various systems were compared.The main conclusions are as following.The interfacial reaction mechanism between carboxylic acid and extractant is affected by the polarity of organic phase,and the addition of polar diluent could effectively improve the extraction efficiency.The salt effect commonly has positive effects on the extraction efficiency,and the application of inorganic salts,such as sodium chloride,could reduce the cost of extraction process.Comparing with the traditional reactive extraction,the use of ionic liquids as extractants is much greener,and the extraction performance of hydrophobic ionic liquids is better than that of others.On the other hand,the extraction kinetics was also summarized to gain insight on the feasibility of extractants and reactive extraction.Finally,the novel extractants and extraction processes,the stripping technology and the extraction kinetics,the salt effects on reactive extraction,and the combination of reactive extraction with other technologies,such as separation,redox,catalysis and adsorption,are provided as the future working directions in the field of reactive extraction.