二(2-乙基己基)磷酸萃取L-色氨酸

以二 (2 -乙基己基 )磷酸 (D2EHPA) -正辛烷 (体系A)及D2EHPA -正辛醇 +正辛烷 (体系B)萃取L -色氨酸为对象 ,研究了D2EHPA浓度、L -色氨酸初始浓度、稀释剂组成以及pH值对萃取平衡分配系数的影响 .结果表明 ,在实验研究涉及的pH值 (1.0     

二（2-乙基己基）磷酸/磷酸三丁酯复合萃取剂协萃对氨基苯甲酸

为强化两性官能团化合物的萃取分离性能,以对氨基苯甲酸（PABA）为被分离溶质,二（2-乙基己基）磷酸（D2EHPA）/磷酸三丁酯（TBP）/正庚烷的混合物为萃取剂进行了萃取平衡特性的研究,考察了溶液的pH值、D2EHPA浓度、TBP浓度对于萃取平衡的影响,建立了复合萃取剂协同萃取PABA的萃取平衡分配系数的表达式.结果表明,D2EHPA/TBP/正庚烷复合萃取剂萃取PABA具有明显的协萃效应,协萃机理为D2EHPA及TBP分别与PABA的Lewis碱性官能团（—NH2）和Lewis酸性官能团（—COOH）缔合形成亲油性更强的萃合物,且D2EHPA与TBP的浓度差异越小,协萃效应越明显.根据萃取平衡分配系数表达式拟合求取了表观萃取平衡常数,复合萃取剂的值远大于D2EHPA、TBP单独作为萃取剂的值,进一步证明了本文提出的协萃机理.     

酶法转化体系中L-苯丙氨酸的络合萃取

L-苯丙氨酸的分离提取对于促进酶法制备工艺的产业化进程具有重要价值。利用络合萃取分配系数、分离选择性高的特点,对苯丙酮酸酶法制备L-苯丙氨酸转化体系中L-苯丙氨酸的络合萃取进行了研究。以二(2-乙基己基)磷酸为萃取剂,研究了水相平衡pH、萃取剂浓度和稀释剂的种类对分配系数的影响;并利用D2EHPA-正辛醇体系对酶法制备L-苯丙氨酸的转化液进行了络合萃取研究,经4次萃取和1次反萃,L-苯丙氨酸的萃取率达到98 15%;经1次反萃,L-苯丙氨酸的收率达94 33%。     

D2EHPA＿PEHEHPA协同萃取磷酸中铁离子的研究

使用D2EHPA(二-(2-乙基己基)磷酸酯)与PEHEHPA(2-乙基己基磷酸单酯)进行协同萃取,以去除磷酸中的铁杂质。考察了萃取剂浓度、萃取时间、萃取温度、萃取相比等因素对磷酸中铁离子萃取率的影响。实验结果表明,当萃取温度为25℃,萃取时间为25min,萃取剂浓度为2mol/L,萃取相比2:1时,铁的单级萃取率最高可达90%。比单独使用D2EHPA与PEHEHPA萃取时的萃取率分别提高了15.38%和18.42%。这一研究结果表明协同萃取的方法在净化湿法磷酸方面具有较好的应用前景。     

二（2—乙基己基）磷酸萃取L—异亮氨酸的研究

以二（２－乙基己基）磷酸（Ｄ２ＥＨＰＡ）－正辛烷及Ｄ２ＥＨＰＡ－正辛醇萃取Ｌ－异亮氨酸为对象,研究了Ｄ２ＥＨＰＡ浓度、Ｌ－异亮氨酸初始浓度以及ｐＨ值对萃取平衡分配系数的影响。结果表明,在实验研究涉及的ｐＨ值范围内,分配系数先随ｐＨ的增加而增大,在３．５〈ｐＨ〈５区域,ｐＨ值对分配系数的影响较小。分配系数还随Ｄ２ＥＨＰＡ浓度的增加而增大。正辛醇加入有机相,萃取分配系数增大。Ｄ２ＥＨＰＡ与Ｌ－异亮氨酸     

三烷基氧膦与二(2-乙基己基)磷酸协萃对氨基苯酚的研究和应用

为考察复合萃取剂萃取两性官能团溶质的协萃机理,以对氨基苯酚(PAP)为分离溶质,三烷基氧膦(TRPO)+二(2 乙基己基)磷酸(D2EHPA)+庚烷为萃取剂进行了萃取平衡特性的研究。结果表明,该萃取剂萃取PAP时,具有明显的协萃效应。协萃机理为TRPO与PAP的中性分子以及D2EPHPA与PAP的中性分子和阳离子反应生成(HP)2·NH2—C6H4—OH·TRPO或者P·NH3—C6H4—OH·TRPO萃合物;萃取剂中D2EHPA与TRPO的适宜协萃比为1∶3;pH是影响萃取能力的关键因素,起始pH值条件下PAP分子形态摩尔分数较大的pH值区域(6—8),分配系数出现极大值;采用适宜的萃取剂组成对PAP的工业生产废水进行处理,可有效去除废水中的PAP和苯胺。     

三烷基氧磷萃取对氨基苯酚的性能

以三烷基氧磷(TRPO)为反应萃取剂,研究了稀释剂种类、溶液pH值等因素对对氨基苯酚稀溶液反应萃取分配系数(D)的影响,提出了同时考虑反应萃取和物理萃取作用的分配系数的表达式.结果表明：TRPO对对氨基苯酚的萃取主要通过与其中性分子的氢键缔合和溶剂化效应实现,D值的变化与中性分子的摩尔分数有关;稀释剂的极性对对氨基苯酚的萃取影响较小;除20%TRPO/正庚烷体系外,拟合实验数据得到的表观萃取平衡常数变化较小;体系的物理萃取分配常数则随TRPO浓度的增大而增大,且符合稀释剂和TRPO的物理萃取能力的简单加和;酸性、碱性和中性的反应萃取剂都可有效地萃取对氨基苯酚,萃取能力为二(2-乙基己基)磷酸＞ TRPO ＞ 三烷基胺,相应的操作pH值为2～3、4～5和6.5～7.5,应用时可根据体系的pH值范围选用相应的萃取剂,而不必调节溶液的pH值.     

乳化萃取法脱除Mg2+制备工业级磷酸二氢钠的研究

本文以高效的二(2-乙基己基磷酸)(D2EHPA)为萃取剂,采用乳化萃取技术来提取NaH2PO4溶液中的Mg2+杂质,通过考察萃取剂浓度,水相溶液pH值,相比(水相:有机相),乳化速度等对萃取Mg2+萃取率的影响,求得适宜工艺条件:D2EHPA体积分数:75%,相比(A/O):2∶1,起始NaH2PO4溶液pH值为4,搅拌速度:3000r.min-1;实验结果表明,在适宜工艺条件下,经过三级萃取,可制取工业级NaH2PO4。     

二(2-乙基己基)磷酸钠离子交换萃取氨基葡萄糖盐酸盐的研究

氨基葡萄糖盐酸盐极性大,传统物理萃取方法分离效果不理想,今采用离子交换萃取方法用二(2-乙基己基)磷酸钠萃取氨基葡萄糖盐酸盐溶液。测定了氨基葡萄糖盐酸盐初始浓度、萃取温度、萃取剂初始浓度、以及pH值对分配系数的影响。结果表明,在其他实验条件相同的情况下,分配系数随温度变化不明显,随二(2-乙基己基)磷酸钠初始浓度增加而增大,随氨基葡萄糖盐酸盐初始浓度增加而减少,随pH值增加先增大后减小;氨基葡萄糖盐酸盐低浓度下的分配系数远大于其高浓度下的分配系数;为获得最佳萃取效果,萃取平衡体系要尽量接近中性。建立了分配系数模型,并讨论了四种特殊情况下的分配系数表达式。研究结果为工业用离子交换萃取法分离氨基葡萄糖盐酸盐提供了一定的技术依据。     

D2EHPA萃取回收Cr(Ⅲ)的研究

以回收废水中Cr(Ⅲ)为目的,选择2-乙基己基磷酸(D2EHPA)为萃取剂,煤油为稀释剂,进行了萃取回收Cr(Ⅲ)的实验研究.考察了皂化剂种类、溶液pH值、助溶剂种类、萃取剂浓度等因素对于萃取平衡影响以及三种无机酸、两种有机酸对于负载Cr(Ⅲ)的D2EHPA反萃效果的影响.结果表明,pH值是影响D2EHPA/煤油萃取Cr(Ⅲ)的重要因素, 在pH＜2时,D2EHPA几乎不萃取Cr(Ⅲ),通过萃取剂的皂化,提高水相pH值,可以实现D2EHPA萃取Cr(Ⅲ).随平衡水相pH值的升高,D2EHPA显示出良好的萃取效果.NaOH溶液作为皂化剂比氨水的分相效果好.加入助溶剂后萃取效率提高,其中10%～20%正辛醇是适宜的助溶剂选择.D2EHPA/正辛醇/煤油萃取Cr(Ⅲ)后立即用无机酸或有机酸反萃,其中硫酸、盐酸或草酸的反萃率能够达到90%以上.     

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     

二（2-乙基已基）磷酸萃取氨基苯甲酸的平衡特性

A series of extraction equilibrium experiments for aminobenzoic acid with di(2-ethylhexyl)phosphoric acid (D2EHPA) dissolved in n-octane or 1-octanol was carried out. The effects of aminobenzoic acid concentration,D2EHPA concentration and pH on the distribution ratio were discussed in detail. The infrared spectra of the organic phase loaded with solute illustrated that pH had little effect on the structure of the complex formed. There proceed ion association and cation-exchange.reaction in the extraction. An expression of the equilibrium distribution was proposed.     

萃取法制备工业级磷酸二氢铵-萃取剂的反萃取研究

本课题以高效的2-乙基己基磷酸(D2EHPA)为萃取剂,采用溶剂萃取法来提取MAP溶液中的Mg2++杂质,从而实现生产高品质MAP的目的;但是实现其产业化的难点之一,就是反萃取剂的选择,而在选择反萃取剂时关键是实现络合物D2EHPA-Fe3+的有效分离,因为络合物D2EHPA-Fe3+是非常稳定的,而且Fe3+的富集能使萃取剂老化.因此,选择有效的反萃取剂来实现D2EHPA的循环回收利用是非常有必要的.以H2SO4+添加剂A为反萃取剂,通过考察反萃取剂浓度,相比,反应温度,反应时间,搅拌速度等对反萃取Fe3+反萃取率的影响,求得最佳工艺条件为H2SO4浓度:4mol· L-1,反应温度45℃,相比为1∶1,搅拌速度550r· min-1,搅拌时间0.5h.     

Extraction Equilibria of 4-Hydroxypyridine using Di (2-ethylhexyl) Phosphoric Acid

Extractions of 4-Hydroxpyridine (4HP) from aqueous solutions using Di(2-ethylhexyl)phosphoric acid (D2EHPA) as extractant in 1-octanol and kerosene were studied. The factors that affected the distribution coefficient (D), such as equilibrium pH, the concentration of D2EHPA, and the type of diluents were discussed. The interaction mechanism between 4HP and D2EHPA was validated by infrared spectroscopic analysis. D increased with the increase of the concentration of D2EHPA and peak values appeared at equilibrium pH = 3.6–5.0. D in the polar diluent (1-octanol) was much higher than those in the non-polar diluent (kerosene). The extraction reaction was found to be a proton-transfer process and D2EHPA mainly reacted through its –OH with –N– of 4HP. The apparent reactive extraction equilibrium constants K ₁₁ and K ₁₂ were obtained by fitting the experimental data of extraction equilibrium. By comparing calculated D values from the proposed model with the experimental ones, the accuracy of the proposed model was examined.     

Synergistic extraction and separation of Fe(III) and Zn(II) using TBP and D2EHPA

Waste chloride pickle liquors from hot-dip galvanizing plants, steel plants and flue dust contain reasonable amounts of heavy metals such as Zn, Cr, Ni, etc. Iron is invariably associated with most of these materials and comes into solution during leaching. Thus, the synergistic extraction of zinc(II) and iron(III) from leach solutions in tri-n-butyl phosphate (TBP)–di(2-ethylhexyl) phosphoric acid (D2EHPA) system diluted in kerosene was investigated. The Zn and Fe concentrations in the leach liquor used in the present study were 2 g/L. Experiments were carried out in the pH range of 0.5–4.0, temperature of 25°C, using sole D2EHPA, sole TBP and D2EHPA–TBP mixtures at different ratios. Results showed that the co-extraction of zinc(II) and iron(III) increased with increasing equilibrium pH using D2EHPA. It is demonstrated that the mixtures of TBP and D2EHPA are more efficient and selective than D2EHPA alone. At low pH values, the separation factor is low when pure D2EHPA is used as an extractant; however, using TBP as a synergist, the separation factor increases and results in a better separation of zinc from iron. Increasing TBP to D2EHPA ratios in the organic phase caused a slight shift to the right in the extraction isotherm of iron and a marked shift to the right in the extraction isotherm of zinc, and the maximum separation factor of 13.3 × 10³ was achieved at a TBP to D2EHPA volume ratio of 4:1 (0.58 M TBP: 0.12 M D2EHPA). Furthermore, the effect of equilibrium pH, organic to aqueous phase ratio and Cl^? concentration on the selective extraction was investigated. Using two extraction stages at the O/A ratio of 2:1 and pH_e (equilibrium pH) of 3 and 1 for zinc and iron, respectively, 99% of zinc(II) and 96.25% of iron(III) were extracted.     

Distribution Behavior of Amino Acid by Extraction with Di(2-ethylhexyl) Phosphoric Acid

Abstract

The distribution equilibrium of l-tryptophan (l-Trp) by extraction with di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in n-hexane was studied. The effects of L-Trp and D2EHPA concentrations, pH, and ionic strength, particularly of L-Trp loading in the organic phase, on extraction equilibrium were examined in detail. When the amino acid loading ratio (the molar concentration ratio of the equilibrium amino acid in the organic phase to the initial dimeric D2EHPA) was less than 3 × 10^?3, one L-Trp molecule was extracted by forming a complex with four monomeric D2EHPA molecules, and the extraction equilibrium constant (K _e) was determined to be 0.045 dm³/mol. Above this loading ratio the equilibrium formula did not hold, and the apparent equilibrium constant (K _a) increased significantly with increasing loading ratio. The phenomenon was explained by taking into account two parallel reactions in which fewer D2EHPA molecules, two and one respectively, were needed to extract one l-Trp molecule.     

有机胺类稀溶液的络合萃取

以P204(磷酸二(2-乙基己基)酯)为络合剂,加氢煤油为稀释剂,实验研究了不同的有机胺类稀溶液的络合萃取特性,讨论了有机胺类的pK_a值、络合剂的含量和溶液pH值等因素对络合萃取平衡的影响,提出了同时考虑络合萃取作用和物理萃取作用的萃取相平衡分配系数表达式。利用傅立叶红外谱图分析了P204络合萃取有机胺类的机理。     

二(2-乙基己基)磷酸萃取氨基苯甲酸的相平衡分配系数

络合萃取法分离极性有机物稀溶液具有高效性和高选择性,本文以二（２－乙基已基）磷酸（Ｄ２ＥＨＰＡ）为络合剂;正辛烷或正辛醇为稀释剂,在不同的ＰＨ值条件下实验测定了氨基苯甲酸稀溶液的萃取相分配系数,讨论了影响因素,分析了萃合物的组成。提出了平衡分配系数的关系式。