十八烷基二甲基苄基氯化铵从碱性氰化液中固相萃取金的研究

基于十八烷基二甲基苄基氯化铵(BDMSAC)与Au(CN)-2络阴离子生成的离子缔合物可被C18反相键合硅胶固相萃取柱萃取、富集,建立了一种从碱性氰化液中高富集倍数固相萃取金的方法。该方法用于从碱性氰化液中固相萃取痕量金,萃取回收率可超过98%,同时研究了C18反向固相萃取金的机理,也创造性地提出了一种从碱性氰化液中提取金的新工艺。     

双水相体系萃取分离金属离子研究进展

双水相体系是一种绿色环保的新型分离技术,应用领域相当广泛,是近年来的研究热点。论述了双水相体系用于萃取分离金属离子的研究现状。根据所使用萃取剂的不同分3种情况进行了论述：不添加任何萃取剂直接萃取金属离子;以无机阴离子为萃取剂,依靠金属阳离子与无机阴离子形成的阴离子配合物（螯合物）而转移到萃取相,萃取金属离子;采用有机试剂作为萃取剂,依靠金属离子与萃取剂反应形成的中性配合物（螯合物）而转移到萃取相,萃取金属离子。论述了双水相体系萃取分离金属离子的发展趋势：建立金属离子在双水相体系中分配的机理模型;双水相体系成相物质的回收及再利用;通过无机盐水化能力的差异,或者通过双水相体系的温度诱导相分离,实现无机盐的分离与常温制备;开展双水相体系萃取分离金属离子的工程研究。     

酶的双水相体系萃取分离技术

双水相体系萃取技术巳被广泛应用于酶的分离纯化。文中介绍了该技术的萃取原理、特点、分配影响因素,以及在酶分离过程中的应用,并指出当前研究工作存在的问题和今后研究的重点。     

双水相萃取分离苦参生物碱

用乙醇、聚乙二醇和Triton X-100与硫酸铵等无机盐构建双水相体系,研究了各体系的形成过程与性质及对氧化苦参碱和苦参碱的萃取性能,发现乙醇/硫酸铵双水相体系稳定、分相快、萃取率高,更适合苦参生物碱的萃取;对其萃取条件的优化结果表明,乙醇和硫酸铵分别为38%(w)和18%(w),体系pH值为7.0,30℃下搅拌萃取15 min,氧化苦参碱与苦参碱的分配系数和萃取率分别为4.46和5.10,96.17%和95.74%. 在苦参的水提取液中直接用该体系萃取分离氧化苦参碱、氧化槐果碱、槐定碱、苦参碱及槐果碱5种生物碱,萃取率为91.03%~94.46%,三级错流总萃取率为97.22%~98.78%;该体系用于苦参生物碱的纯化,可显著减小杂质含量,苦参碱含量可提高1倍以上,其焓变DH0和熵变DS0均大于0,且DG0<0,表明萃取过程为吸热熵增的自发过程.     

双水相萃取分离纯化叶黄素

研究了3种萃取叶黄素的双水相体系,即传统的双水相体系聚乙醇/硫酸铵体系和基于与水互溶的有机溶剂的新型双水相萃取体系:乙醇/硫酸铵及乙醇/磷酸氢二钾体系。通过实验确定了最佳双水相萃取体系:乙醇/硫酸铵双水相体系,w(乙醇)=40.17%,w(硫酸铵)=8.98%,最大分配系数为90.83,最大收率为99.88%。乙醇/硫酸铵双水相体系的最佳诱导条件是在25±1℃时超声10min。超声结束后,分液,将富含叶黄素的相浓缩,内含硫酸铵晶体,利用乙醇洗涤硫酸铵晶体,溶解叶黄素,抽滤,将滤液浓缩后干燥,得到叶黄素。叶黄素通过HPLC色谱法进行纯度的测定。     

双水相体系萃取木瓜蛋白酶的研究

采用聚乙二醇(PEG)/(NH4)2SO4双水相体系对木瓜蛋白酶进行萃取分离,研究了PEG相对分子量、PEG质量分数、(NH4)2SO4质量分数和pH值对木瓜蛋白酶分配系数及酶活力回收率的影响.结果表明,最佳萃取条件为:PEG4000质量分数6%、(NH4)2SO4质量分数18%、pH值6.0,在此条件下,木瓜蛋白酶的...     

双水相体系萃取槐米中芸香甙的研究

利用双水相萃取技术提取分离槐米中的芸香甙,以异丙醇/硫酸铵为双水相萃取体系,研究异丙醇质量、硫酸铵质量、水质量、槐米质量等因素对萃取效果的影响。结果表明:在异丙醇质量为18 g,硫酸铵质量为11.5 g,水质量为27 g,槐米质量为1 g的萃取条件下,提取率为21.7%,含量为94.8%。该方法可用于槐米中芸香甙的提取分离。     

双水相体系萃取天冬氨酸转氨酶

研究了不同的双水相体系对天冬氨酸转氨酶的萃取分离效果,对聚乙二醇/无机盐成相系统进行了系统的研究,初步确定PEG1000 Na2HPO4为研究体系,并考察体系pH值、无机盐对双水相体系分配系数和纯化系数的影响。当PEG1000的质量分数为18%、Na2HPO4的质量分数为20%时,双水相体系对天冬氨酸转氨酶的分离系数和纯化系数分别为2 36和2 94。     

乳状液膜法提取分离水中苯胺

采用非流动载体乳状液膜体系对水中苯胺的提取进行了研究.考察了影响苯胺传质的几种因素：内水相盐酸浓度、外水相pH值、表面活性剂种类和浓度、乳水比等.结果表明,在适宜的操作条件下,当水中苯胺浓度为500 mg·L^-1时,经过一级液膜处理,水中苯胺的含量可降到1.5 mg·L^-1.另外初步探讨了表面活性剂的结构和性质对膜相黏度、界面黏度、稳定性和苯胺传质速率的影响.     

THE EXTRACTION OF SILVER FROM CYANIDE SOLUTIONS WITH ION EXCHANGE RESINS

ABSTRACT

The ability of various ion exchange resins to extract silver from synthetic cyanide solutions was evaluated. It was found that weak base resins such as DUOLITE A-7, DOWEX WGR-2, DOWEX MWA-1, DOWEX XFS-4195, and AMBERLITE IRA-35 extract silver significantly only when the pH is lower than 8. At higher pH, the same resins exhibited little or no silver extraction. A comparison among weak base resins showed that DUOLITE A-7 and DOWEX MWA-1 have the best characteristics in terms of capacity and elution efficiency.

Strong base resins such as DOWEX MSA-1 and AMBERLITE IRA-910 extract silver in the entire pH range from 4 to 12. When the aqueous feed solution contains only one metal, these resins have a significantly larger capacity for silver than for copper, iron or zinc. But, if one or more base petals are added to the cyanide feed solution, the silver extraction is depressed to an extent which depends on the contact time. The silver extraction can be maximized by decreasing the concentration of free cyanide in the aqueous solution and by stopping the extraction before the resin attains the saturation point     

PARTITIONING OF AROMATIC MOLECULES IN AQUEOUS BIPHASIC SYSTEMS

ABSTRACT

Aqueous biphasic systems (ABS) may be suitable for the separation of aromatic molecules in industrial and environmental settings; hence it is invaluable to have predictive models of partitioning behavior in these systems for design and evaluation purposes. In a continuing study of the partition of small aromatic organic molecules, the distribution of several relatively hydrophilic substituted benzene species is reported. The partitioning behavior of five charged substituted benzene species (phthalic acid, 4-hydroxybenzoic acid, benzoic acid, salicylic acid, and p-toluic acid) and one uncharged species (1,3-dinitrobenzene) has been studied in ABS prepared from stock solutions of 40% (w/w) PEG-2000 and increasing concentrations of four water-structuring salts [K₃PO₄, K₂CO₃, (NH₄)₂SO₄, and NaOH]. Comparison has been made with published data on the partitioning of these solutes in 1-octanol/water biphasic systems. In general, the partition of these species may be understood in terms of the free energy of hydration of the salt forming the ABS and the dissociation of the charged groups of the distributed solutes.     

LIQUID-LIQUID EXTRACTION OF MOLYBDENUM(VI) FROM AQUEOUS ACID SOLUTIONS BY HIGH-MOLECULAR WEIGHT AMINES

The extraction of molybdenum(VI) from hydrochloric, nitric and sulphuric acid solutions by trioctyl-amine and tricaprylmethylannnonium chloride in benzene has been investigated under various conditions. The equiliblium expressions are proposed on the basis of the distribution data.     

THERMODYNAMIC EQUILIBRIA OF THE EXTRACTION OF CHROMIUM(VI) WITH TRI-N-OCTYLPHOSPHINE OXIDE FROM AQUEOUS SOLUTIONS

ABSTRACT

The distribution of chromium( VI ) between aqueous solutions and the kerosene solutions of tri-n-octyl-phosphine oxide (TOPO) have been studied at 25 °C and pH 2-4, in which range the predominant forms of Cr(VI) are HCrO₄ and Cr₂O₇ ^2?. The extraction equilibrium is influenced by the total chromium(VI) concentration, aqueous pH value, and total extractant concentration. The thermodynamic equilibria among all species in the aqueous phase were used for the analysis of distribution data, and the activity coefficients of ionic species were estimated according to Debye-Hiickel or Bromley equation. By numerical method, the complexes of Cr(VI ) with TOPO formed in the organic phase were found to be H₂CrO₄ (TOPO) and H₂Cr₂O₇ (TOPO) ₃. The corresponding extraction constants were 2019 and 3.69× 10⁸, respectively.     

PARTITIONING BEHAVIOR OF PORPHYRIN DYES IN AQUEOUS BIPHASIC SYSTEMS

ABSTRACT

The partition of protoporphyrin IX and the phthallocyanine dye, propyl astra blue iodide, in aqueous biphasic systems (ABS) and onto aqueous biphasic extraction chromatographic (ABEC?) resins has been examined. Solubility of protoporphyrin IX was found to be too low for recovery by ABS other than by use of thermoseparating surfactants. Partitioning behavior of the phthallocyanine dye was found to depend on the salting-out strength of the salt. As a result of the partition of this dye to the interface of ABS, the adoption of ABEC for recovery of this dye is more favorable.     

EXTRACTION OF TITANIUM(IV) FROM AQUEOUS HYDROCHLORIC ACID SOLUTIONS INTO ALAMINE 336-M-XYLENE MIXTURES

Extraction of Ti(IV) from its aqueous hydrochloric acid solutions into organic Alamine 336-m-xylene systems was investigated. Extraction experiments were conducted with three different initial metal concentrations of 1, 3, and 6 mg/mL, each at three acidic molarities of 1, 5, and 10 M. It was observed that the extractability of Ti(IV) increases with increasing acidic molarities. Alamine 336 diluted with m-xylene was found to be a suitable extractant for Ti(IV) across this acidic range. In parallel, a mathematical model was developed to correlate metal extractability and Alamine 336 volume content. Optimal Alamine 336 contents were estimated for single-stage extraction.     

EXTRACTION OF TITANIUM(IV) FROM AQUEOUS HYDROCHLORIC ACID SOLUTIONS INTO ALAMINE 336-M-XYLENE MIXTURES

Extraction of Ti(IV) from its aqueous hydrochloric acid solutions into organic Alamine 336-m-xylene systems was investigated. Extraction experiments were conducted with three different initial metal concentrations of 1, 3, and 6 mg/mL, each at three acidic molarities of 1, 5, and 10 M. It was observed that the extractability of Ti(IV) increases with increasing acidic molarities. Alamine 336 diluted with m-xylene was found to be a suitable extractant for Ti(IV) across this acidic range. In parallel, a mathematical model was developed to correlate metal extractability and Alamine 336 volume content. Optimal Alamine 336 contents were estimated for single-stage extraction.     

LIQUID-LIQUID EXTRACTION OF 2,3-BUTANEDIOL FROM DILUTE AQUEOUS SOLUTIONS WITH MIXED SOLVENTS

Distribution coefficients for the liquid-liquid extraction of 2,3-butanediol (5wt%) in aqueous solutions with binary mixtures of 4-nonylphenol (0-67 vol%), toluene and several alcohols, (2-ethyl-l-hexanol, 1-oclanol and 1-decanol) at 25°C are reported. The distribution coefficients were in the following ranges: 4-nonylphenol + toluene (0-0·23), 4-nonylphenol + 2-ethyl-l-hexanol (0·23 - 0·27), 4-nonylphenol + 1-octanol (0.21-0·33) and 4-nonylphenol + 1-decanol (0·22-0·37). The largest distribution coefficient was found to be 0·37 for the mixed solvent 4-nonylphenol+1-decanol (50vol%), which shows a slight decrease in the separation factor. Activity coefficients at infinite dilution were determined using the MOSCED model and a similar trend for all the solvent mixtures of 4-nonylphenol and alcohols was found.     

GOLD EXTRACTION FROM THIOSULFATE SOLUTIONS USING MIXED AMINES

ABSTRACT

The extraction of gold from thiosulfate solutions with amine oxide and its mixture with amines has been studied, the results show that the amine oxide (TRAO) has a higher extraction ability for gold compared with tertiary amine. It can extract gold from neutral and weakly alkaline thiosulfate solutions, similar to the primary amine as extractant. The addition of TRAO enhances the extent of gold extraction with primary, secondary, and tertiary alkyl amines, respectively. The stoichiometry for the extraction of gold from thiosulfate solutions using the mixed solvent containing the primary amine N₁₉₂₃ and the amine oxide TRAO was investigated using slope analysis. The compositions of the gold extraction species with mixed organic solvents are proposed.