新型PVC/OHA/D2EHPA基膜增强型聚合物包容膜的制备及性能评价

为解决聚合物包容膜(PIM)传输效率低的问题。制备了一种以聚氯乙烯(PVC)为基体,包含固液两种载体的基膜增强型PIM。以N-羟基正辛酰胺(OHA)作为新型载体固定于基膜孔道内,利用其与有机萃取剂二(2-乙基己基)磷酸酯(D2EHPA)的协同作用,实现高效传质。对制备的基膜增强型PIM进行SEM、EDS、FTIR、XPS、力学性能以及传质性能考察与表征。结果表明,载体配比为22% OHA+17% D2EHPA的基膜增强性PIM对50 mg/L的Zn_²⁺的10h回收效果最佳,萃取率和反萃率分别为59.86%和51.10%。5个周期的运行实验中,基膜增强型PIM初始传质通量为587.36 mg.m_^-2.h_^-1,约是仅包含液相萃取剂PIM传质通量(312.64 mg.m_^-2.h_^-1)的2倍。5个循环周期结束后,基膜增强型PIM传质通量仍高于仅包含液相萃取剂PIM传质通量。     

PC-88A-煤油-HCl分散支撑液膜体系中Zn(Ⅱ)的传输与分离研究

以聚偏氟乙烯膜(PVDF)为支撑体,煤油为膜溶剂,2-乙基己基膦酸-单-2-乙基己基酯(PC-88A)为流动载体,研究了分散支撑液膜体系中金属Zn(Ⅱ)的传输行为;考察了料液pH、膜溶液与解析剂体积比和解析相中HCl浓度对Zn(Ⅱ)传输的影响.结果表明,以HCl为解析剂,料液pH为4.0、膜溶液与解析液体积比为160:40、解析相中HCl浓度为4.0 mol·L-1时,该分散支撑液膜体系对金属Zn(Ⅱ)具有良好的传输作用,传输190 min,传输率可达90%,在相同的条件下传统的支撑液膜只有72.8%.在Zn(Ⅱ)的最佳传输条件下,对Zn(Ⅱ)/Cu(Ⅱ)、Zn(Ⅱ)/Co(Ⅱ)进行了分离试验,分离效果很好,该体系能够实现金属离子的传输和分离.     

分散支撑液膜体系中Cd(Ⅱ)的传输研究

以聚偏氟乙烯膜(PVDF)为支撑体,煤油为膜溶剂,2-乙基己基膦酸-单-2-乙基己基酯(PC-88A)为流动载体,研究了分散支撑液膜体系中金属Cd(Ⅱ)的传输行为;考察了料液pH、膜溶液与解析剂体积比、解析相中HCl浓度以及Cd(Ⅱ)的起始浓度对Cd(Ⅱ)传输的影响.结果表明,以HCl为解析剂,料液pH=5.0、膜溶液与解析液体积比为160:40、解析相中HCl浓度为4.0 mol·L-1时,该分散支撑液膜体系对金属cd(Ⅱ)具有良好的传输作用.在最优条件下,料液相中Cd(Ⅱ)的初始浓度为3.00×104mol·L-1时,传输190min,传榆率可达82.65%.     

2-乙基己基膦酸单(2-乙基己基)酯萃取钯(Ⅱ)的热力学研究

本文研究了2-乙基已基磷酸单（2-乙基已基）酯（P507）萃取钯（Ⅱ）的热力学过程．通过考察P507浓度对Pd（Ⅱ）分配比的影响，调出了萃取反应的表观平衡常数k、焓变△H、自由能变△G和熵变△S．     

分散支撑液膜中四价铈的传输分离

研究了以聚偏氟乙烯膜(PVDF)为液膜支撑体,煤油为膜溶剂,2-乙基己基磷酸-单-2-乙基己基酯(PC-88A)为流动载体,煤油和PC-88A的混合溶液作为膜溶液,膜溶液和HCl溶液组成分散相的分散支撑液膜(DSLM)中Ce(IV)的传输行为;考察了料液相酸度、Ce(IV)起始浓度、HCl浓度、膜溶液与HCl溶液体积比、解析剂及载体浓度对Ce(IV)传输的影响,得出其最优传输分离条件为：HCl浓度4.0 mol/L,膜溶液与HCl溶液体积比2:1,载体浓度0.16 mol/L,料液相中HCl浓度0.1 mol/L. 在最优条件下,料液相中Ce(IV)的初始浓度为0.7′10-4 mol/L时,迁移75 min,其迁移率达到96.3%. 提出了Ce(IV)在DSLM中的传质动力学方程,得出Ce(IV)在膜中的扩散系数为6.69′10-8 m2/s,料液-膜边界层厚度为19.3 mm. 对模拟样品Ce(IV)的分离结果表明,在一定条件下,125 min内模拟煤粉灰中Ce(IV)迁移率达到92.8%;105 min内模拟冶金熔渣中其迁移率可达92.6%;215 min内Ce(IV)与Eu(III)的混合液中Ce(IV)迁移率达到83%,其他元素迁移率极低.     

含金属离子赖氨酸水溶液的萃取分离

采用二(2-乙基己基)磷酸(P204)作萃取剂,航空煤油作稀释剂,对含有钙、镁、钠、钾等金属离子的赖氨酸水溶液进行萃取,以蒸馏水作为反萃取剂对有机相进行反萃取分离实验.结果表明,原料液初始pH值在4～5、P204与煤油体积比为3:2、有机相与水相比为2:1、反应萃取时间大于30min、搅拌转速约200rpm时,能够取得较好的萃取效果.以初始pH值≥3.5的蒸馏水为反萃取剂,蒸馏水与有机相体积比4:1,在150rpm的转速下搅拌20min能够较为完全地分离出赖氨酸,然后在其它条件相同的情况下,用初始pH＜1的蒸馏水对有机相再次反萃取可分离出金属离子,从而实现萃取剂的重复利用.     

2-氯乙基膦酸二-(2-氯乙基)酯的合成新方法

研究了标题化合物的合成新方法。以2-氯乙基膦酸二酰氯为原料,与环氧乙烷反应制备得到产物,其气相纯度98%,收率98%。利用1HNMR、13CNMR、31PNMR和HRMS表征确定产物结构,并探讨了反应原料配比、溶剂等对反应的影响,所合成的产物可在分析测试方法开发中直接作为标样使用。     

二（2—乙基己基）单硫代膦酸的合成及其对金属离子的萃取

二(2-乙基己基)膦酸是工业生产中广泛应用的一种萃取剂。将其分子中的氧原子换成硫原子,可得二(2-乙基己基)二(单)硫代膦酸。这两种萃取剂对多种金属离子都有较强的萃取能力。将单硫代膦酸分子中的两个烷氧基换为两个烷基。即得二(2-乙基己基)单硫代膦酸。对其合成国外已有报道。但对其萃取金属离子的研究至今尚未见有报道。本文研究了新型萃取剂二(2-乙基己基)单硫代膦酸的合成、结构鉴定及其萃取各种金属离子的性能,为其在分离、提纯中的应用提供了依据。     

皂化HA/煤油微乳液萃取赖氨酸的研究

研究了NaOH皂化HA/煤油微乳体系萃取赖氨酸的机理和工艺,考察了NaOH浓度、萃取时间、乳水比、外水相pH值、油相重复使用次数等对萃取效率的影响.结果表明,该微乳液萃取赖氨酸的最佳工艺条件为:油相中HA的浓度1.0 mol·L-1、NaOH浓度1.25 mol·L-1、萃取时间10 min、乳水比(体积比)1:4、外水相pH值3.0,此时,赖氨酸的一次性萃取率可达90.2%.该微乳液具有稳定性好、无明显溶胀和泄漏、萃取效率高、可自动破乳且油相可重复使用等优点.     

PC-88A为载体的大块液膜体系Cu(II)传输动力学

采用以2-乙基己基膦酸-2-乙基己基单酯(PC-88A)为载体、CHCl3为膜溶剂的大块液膜分离体系,研究了搅拌速度、载体浓度、体系温度对铜离子迁移的影响. 获得了不同反应温度下的表观反应速率常数,萃取与反萃取表观反应活化能分别为41.97和8.59 kJ/mol. 铜离子的迁移过程可用2个串联的准一级不可逆过程描述,萃取过程化学反应为控速步骤,反萃取过程扩散为控速步骤.     

非离子表面活性剂TX114浊点萃取D2EHPA的规律

引言浊点萃取[1-2]是利用表面活性剂水溶液的增溶和分相行为实现溶质富集的分离技术。由于分相后表面活性剂的富集相(亦称凝聚相)与水相的体积比非常小(0.007～0.04)[3],所以,对于被增溶的物质能够提供非常高的富集倍数和萃取效率。目前浊点萃取技术主要广泛应用于痕量有害物质     

Transport of cobalt(II) through a hollow fiber supported liquid membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier

This work presents experimental, modeling and simulation studies for Co²⁺ ion extraction using hollow fiber supported liquid membrane (HFSLM) operated in a recycling mode. Extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA) diluted with kerosene has been used as the membrane phase. The Co²⁺ ion concentration in the aqueous feed phase was varied in the range of 1–3 mM. Also, D2EHPA concentration was varied in the range of 10–30% (v/v). A mass transfer model has been developed considering the complexation and de-complexation reactions to be fast and at equilibrium. Equations for extractant mass balance and counter-ion (H⁺) transport have also been incorporated in the model. Extraction equilibrium constant (K_ex) for cobalt–D2EHPA system has been estimated from equilibration experiments and found to be 3.48 × 10⁻⁶. It was observed that the model results are in good agreement with the experimental data when diffusivity of metal-complex (D_m) through the membrane phase is 1.5 × 10⁻¹⁰ m²/s. Feed phase pH and strip phase acidity had negligible effect on the extraction profiles of Co²⁺ ions. An increase in D2EHPA concentration increased extraction rates of Co²⁺ ions. The membrane phase diffusion step was found to be the controlling resistance to mass transfer.     

Separation of Ni(II) and Cd(II) Ions with Supported Liquid Membranes (SLM) using D2EHPA as a Carrier

Separation of nickel(II) and cadmium(II) ions from sulphate solution with use of supported liquid membranes (SLM) has been studied. Di(2-ethylhexyl)phosphoric acid (D2EHPA) dissolved in kerosene was used as the ion carrier. Obtained data were compared with data from polymer inclusion membranes (PIM) experiments. It was shown that use of SLM membranes enables separation of Ni(II) and Cd(II) ions. Experimental results data show that faster transport and higher recovery factor values were obtained for supported liquid membranes.     

Separation of cadmium(II) from spent nickel/cadmium battery by emulsion liquid membrane

Experiments were conducted to investigate the separation of cadmium(II) from spent nickel/cadmium battery by emulsion liquid membrane. Liquid membrane mainly consisted of a diluent (kerosene), a surfactant (Span 80), a carrier (di(2‐ethylhexyl) phosphoric acid, D2EHPA) and an internal phase (sulfuric acid). Main research effort was focused on the identification of optimal parameters affecting the separation process, such as D2EHPA (4.4 vol%), Span 80 (6.6 vol%), pH in the external phase (3.0), treat ratio (0.4), agitation time (10 min), and sulfuric acid concentration (1500 mol / m³). With the selected emulsion liquid membrane to separate cadmium(II) from the leaching solution of spent nickel/cadmium battery, the fraction extracted of cadmium(II) ions (0.963) was much more than that of nickel(II) ions (0.026). The organic membrane phase after demulsification was re‐mulsification and recycled up to eight times.     

Extraction equilibria and separation of phenylalanine and aspartic acid from water with di(2‐ethylhexyl)phosphoric acid

The distribution equilibria of single and binary L ‐phenylalanine and L ‐aspartic acid between water and a kerosene solution of di(2‐ethylhexyl)phosphoric acid (D2EHPA) were studied. It was shown that the distribution ratios of phenylalanine generally increased with increasing aqueous pH (2–5) in the D2EHPA concentration range 0.1–0.5 mol dm^?3, but those of aspartic acid decreased with increasing solution pH. Different reaction stoichiometries were proposed for the extraction of phenylalanine and aspartic acid under the conditions studied. The extraction equilibrium constants were obtained. Competitive extraction in binary systems was more apparent in the pH range where the cationic form of amino acids was not predominant. The present results indicated that selective separation of phenylalanine to aspartic acid was possible with this cationic extractant when they were extracted at higher pH and stripped using higher acidity of HCl solution. Copyright © 2006 Society of Chemical Industry     

中空纤维支撑液膜萃取Cu(II)的传递性能

The transport of Cu(II) from aqueous solutions containing buffer media through hollow fiber supported liquid membrane (HFSLM) using di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in kerosene as membrane phase and hydrochloric acid as striping phase was investigated. A set of factors were studied, including tube side velocity, shell side velocity, pH of the feed phase, Cu(II) concentration in the feed phase, buffer media concentration and D2EHPA concentration in the membrane phase. Experimental results indicate that the mass transfer coefficient increases with increasing both carrier concentration in the organic phase and flow rates on the tube side and shell side, and decreases with increasing initial Cu(II) concentration in the feed phase. With increasing pH value and acetate concentration in the feed phase, the mass transfer coefficient reaches a maximum value then decreases. The optimal operating conditions are obtained at pH value of 4.44 and 0.1 mol&;#8226;L－1 acetic ion concentration in feed phase, and carrier volume fraction of around 10% in kerosene as organic phase. A mathematical model of the transport mechanism through HFSLM is devel-oped. The modeled results agree well with the experimental ones.     

Studies on the Separation and Recovery of Thorium from Nitric Acid Medium using (2-ethyl hexyl) Phosphonic Acid,Mono (2-ethyl hexyl) Ester (PC88A)/N-Dodecane as Extractant System

This paper deals with the studies on the separation and recovery of thorium and 233-uranium from nitric acid medium using (2-ethyl hexyl) phosphonic acid, mono (2-ethyl hexyl) ester/n-dodecane as an extractant system. The different extraction parameters were investigated. The distribution ratio of thorium decreased with increase in nitric acid concentration. The optimum solvent concentration for quantitative separation of thorium from aqueous feed solution was 0.75 M of PC88A whereas dodecane was the most suitable of diluents with an organic to aqueous phase ratio of 1:1. Among the various strippants used, 2 M solution of (NH₄)₂CO₃ was found to be the most suitable for back extraction of thorium. The developed method was used to recover thorium and ²³³U from radioanalytical waste generated during thorium analysis by ethylene diamine tetraacetic acid (EDTA) titremtric method and recoveries for both Th and U were more than 85%.     

Sorption Behavior of Y(III) from Chloride Medium with Polymer Composites Containing Di-2-ethyl Hexyl Phosphoric Acid and Multiwall Carbon Nanotube

Extractant impregnated polyethersulfone beads have been prepared by phase inversion method and investigated for yttrium recovery from aqueous medium. The effect of experimental parameters on yttrium sorption has been studied. Quantitative sorption of yttrium (> 90%) was attained after 8 hours of equilibration time in the case of D2EHPA impregnated composite beads. Analysis of sorption data by different kinetic and diffusion models suggested that the sorption of Y(III) followed the pseudo-second order model. Stability tests with polymeric composite beads by multiple cycles of sorption and desorption of Y(III) have established the feasibility of reusing the beads for sorption of metal ions.     

Membrane stability and enrichment of nickel in the liquid emulsion membrane process

The parameters affecting the stability of a liquid emulsion membrane (LEM) for enrichment of nickel were studied. The liquid membrane is made up of a carrier (di‐2‐ethylhexylphosphoric acid), organic diluent and an emulsifying agent (sorbitan monooleate). Swelling of the internal phase during extraction results in breakage of the emulsion. The role of pH is very important in the LEM process for extraction of nickel. A significant decrease in swelling was observed by maintaining the pH of the feed phase constant during extraction. A lower osmotic pressure difference between the external and internal phase brings about lower changes in the swelling and membrane breakdown. © 2000 Society of Chemical Industry