Intensified reactive extraction of 4-hydroxypyridine with di(2-ethylhexyl) phosphoric acid in 1-octanol by using tributyl phosphate

The efficient separation of amphoteric organic compounds from dilute solutions is of great importance in the industrial field. In the present work, the reactive extractions of 4-hydroxypyridine(4-HP) with tributyl phosphate(TBP), di(2-ethylhexyl) phosphoric acid(D2EHPA) and TBP + D2EHPA dissolved in 1-octanol were investigated, respectively. The influences of the initial concentrations of TBP, D2EHPA and TBP + D2EHPA on distribution ratio(D) were discussed, as well as the reactive extraction mechanism were proposed. The obvious intensification effect was observed when the mixture of TBP and D2EHPA was used as extractant. The best extraction conditions were found to be of the molar ratio of D2EHPA and TBP at 2:1 and the equilibrium aqueous pH at 3.50-4.50. D values increased with the increase of the total concentration of TBP and D2EHPA in 1-octanol. Especially, the analysis on the extraction mechanisms clearly indicate(i) TBP in 1-octanol shows negligible reactive extraction toward 4-HP,(ii) D2EHPA in 1-octanol exhibits moderate extraction effect by forming 4-HP:D2EHPA(1:1) and 4-HP:2D2EHPA(1:2) type complexes, while(iii) D2EHPA in TBP/1-octanol demonstrates the maximum distribution ratio with the 4-HP:D2EHPA(1:1) type complex domination. The discussion provides new insights on the mechanism and opens a new way for the intensified extraction of amphoteric organic compounds by using the mixture of multiple extractants in the diluent.

Selective extraction of In(Ⅲ),Ga(Ⅲ) and Zn(Ⅱ) using a novel extractant with phenylphosphinic acid

A new extractant, [N,N-di（2-ethylhexyl）aminolmethylphenylphosphinic acid （DEAPP）, was synthesized to de- velop the mutual separation techniques of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ）. The extraction selectivity for In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1 mob L 1 aqueous ammonium nitrate solution with DEAPP was in the following order： In（Ⅲ） 〉 Ga（Ⅲ） 〉 Zn（Ⅱ）. These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of ln（Ⅲ）, Ga（Ⅲ） and Zn（ll）. The extraction equilibria of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP （ = HR） were expressed by the following reactions： In3＋ ＋ 2（HR）2 InR3（HR） ＋ 3H＋, Ga3＋ ＋ 1.5（HR）2 ＋ N- = GaR2（HR）（NO3） ＋ 2H＋, and Zn2＋ 4- 2（HR）2 ZnR2 （HR） 2 determined 4- 2H＋. The extraction equilibrium constants of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP were to be Kex, M = 1.7 × 104 [dm3.mol 1], 4.17 [（dm3.mol-1）s], and 1.55 × 10 2 [-], respectively.

Centrifugal extraction of rare earths from wet-process phosphoric acid

Phosphorite ore is a potential resource of rare earths （RE） as well as phosphate; therefore, the recovery of RE from wet-process phosphoric acid （WPA） is promising. This study investigated the influence of rotational speed, extractant concentration, flow ratio and phase contact time on the centrifugal extraction of RE from WPA and the separation of RE from impurities. The results indicate that higher rotational speed, higher extractant concentration and larger flow ratio are beneficial to the extraction of RE and impurities from phosphoric acid. It is found that the phase contact time for efficiently extracting RE and that for iron are of great difference, which provides an effective method for separating RE from iron using the non-equilibrium extraction process in centrifugal contactors. Compared with equilibrium extraction, the separation factor βRE/Fe is enhanced from 0.07 to 17.6.

Synergistic extraction of rare earth by mixtures of 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester and di-(2-ethylhexyl) phosphoric acid from sulfuric acid medium

The extraction of Nd^3＋ and Sm^3＋, including the extraction and stripping capability as well as the separation effect of Nd^3＋ or Sm^3＋, from a sulfuric acid medium, by mixtures of di-（2-ethylhexyl） phosphoric acid （HDEHP, H2A2（0）） and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester （HEH/EHP, H2L2（0）） were studied. The distribution ratios and synergistic coefficients of Nd^3＋ and Sm^3＋ in different acidities were also determined. A synergistic extractive effect was found when HDEHP and HEH/EHP were used as mixed extractants for Sm^3＋ or Nd^3＋. The chemical compositions of the extracted complex were determined as Nd.（HA2）2-HL2 and Sm.（HA2）2-HL2. The extraction equilibrium constants, enthalpy change, and entropy change of the extraction reaction were also determined.

Separation of Indium and Iron from Dilute Sulphate Solutions with a Phosphorous Mixer Extractant

The phosphorous mixer introduced could replace D2EHPA as an extractant applied in the extraction of indium. The extraction properties of the phosphorous mixer were studied. The influences of extractant concentration, organic/aqueous (O/A) phase ratio, equilibrium time, and pH value of the feed solutions on the extraction of indium, and separation of indium-iron were investigated experimentally. Under the best operating conditions, more than 98% of indium. was extracted through two-stage counter-current extraction. The optimizing condition of indium extraction is determined as follows: O/A = 1 : (9-12) in volume ratio; 30% PPD in sulphonated kerosene; pH of the feed, about 0.6; equilibrium time, 3-5 min. The extractant has good reusing and anti-aging properties.

Recycle use of phosphorous mixer extractant to extract indium

The stripping and regeneration of the loaded organic phase of phosphorousmixer extractant (PPD) were studied. The mixed solutions (3 mol/L HCl +2 mol/L ZnC1_2) were used asthe stripping agent and more than 99 percent of indium can be stripped after three-stage strippingwhen the volume ratio of organic phase to stripping agent is 1:1. The organic phase can he recycledto use alter regeneration with HCl. The parallel contrast experiments with D_2EHPA (di-2-ethyl hexylphosphoric acid) were carried out under the same conditions. The results show that the mixerextractant has good reusability and the stripping and regeneration of PPD are superior to those ofD_2EHPA.

KINETICS OF ALUMINUM EXTRACTION WITH DI—2-ETHYLHEXYL PHOSPHORIC ACID

The kinetics of solvent.extraction of aluminum with di-2-ethylhexyl phosphoric acid(DEHPA)in n-heptane have been studied in a constant interfacial area cell.A HC1-KHC8H404(potassium biphthalate.KHL)buffer solution was used to maintain a constant pH during extraction.The effects of the concentration of aluminum,pH,the concentration of the extractant,the interfacial area and the temperature on the extraction rate were investigated.A method has been invented to determine amont of the extracted aluminum in the organic phase with 8-hydroxyquinoline.Based on calculation of the coordination states of the aluminum ions and their contribution to the reaction rate,a raaction mechanism which includes two main reaction paths,has been proposed to describe the process.One path starts from Al(H_(2)O)6^(+).and the other starts from Al(H_(2)O)6^(+).The reaction could take place both in the aqueous phase and at the interface.The main reaction region could be changed as the conditions of extraction were changed.When[HA]<0.03 mol/L the process was controlled by the interfacial reaction,and when[HA]>0.03 mol/L it was shifted to a homogeneous aqueous solution reaction.

Arsenic removal from contaminated soil using phosphoric acid and phosphate

Laboratory batch experiments were conducted to study arsenic （As） removal from a naturally contaminated soil using phosphoric acid （H3PO4） and potassium dihydrogen phosphate （KHEPO4）. Both H3PO4 and KHEPO4 proved to reduce toxicity of the soil in terms of soil As content, attaining more than 20% As removal at a concentration of 200 mmol/L. At the same time, acidification of soil and dissolution of soil components （Ca, Mg, and Si） resulted from using these two extractants, especially H3PO4. The effectiveness of these two extractants could be attributed to the replacement of As by phosphate ions （PO4^3-）. The function of H3PO4 as an acid to dissolve soil components had little effects on As removal. KH2PO4 almost removed as much As as H3PO4, but it did not result in serious damage to soils, indicating that it was a more promising extractant. The results of a kinetic study showed that As removal reached equilibrium after incubation for 360 rain, but dissolution of soil components, especially Mg and Ca, was very rapid. Therefore dissolution of soil components would be inevitable if As was further removed. Elovich model best described the kinetic data of As removal among the four models used in the kinetic study.

Separation of Red (Y_2O_3: Eu^(3+)), Blue (Sr,Ca,Ba)_(10)(PO_4)_6Cl_2: Eu^(2+) and Green (LaPO_4:Tb^(3+),Ce^(3+)) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3： Eu^3＋）, blue （Sr, Ca, Ba）10（PO4）6Cl2： Eu^2＋ and green （LaPO4： Tb^3＋, Ce^3＋） fine tricolor phosphor powders was established. First, the green phosphor was extracted and separated from three phosphor mixtures in heptane/DMF（N, N-Dimethylformamide） system using stearylamine or laurylamine （DDA） as the cationic surfactant. Then, after being treated with 99.5% ethanol, the blue and red phosphors could be separated in Heptane/DMF system in presence of 1-octanesulfonic acid sodium salt as the anionic surfactant. Satisfactory separation results have been achieved through two steps extractions with their artificial mixtures. The grades and recovery of separated products reached respectively as follows： red product was 95.3% and 90.9%, blue product was 90.0% and 95.2%, and green product was 92.2% and 91.8%.

Separation of Red (Y_2O_3:Eu^(3+)), Blue (BaMgAl_(10)O_(17):Eu^(2+)) and Green (CeMgAl_(10)O_(17):Tb^3) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3：Eu^3＋）, blue（BaMgAl10O17：Eu^2＋） and green （CeMgAl10O17：Tb^3） rare earth fluorescent powders was proposed. At first, the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone （TTA） dissolved in heptane at alkaline pH condition, then, chloroform was used for extracting the green powder into organic phase. The red phosphor remains in aqueous phase with potassium sodium tartrate depressant （PST）. Therefore, three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction, and grades and recovery of separated products reach respectively as follows： red is 96.9% and 95.2%, blue is 82.7% and 98.8%, green is 94.6% and 82.6%.

溶剂萃取法自铝材抛光废液中分离去除硫酸及其机理的研究

研究了利用溶剂萃取体系自铝材抛光废液中分离去除硫酸并纯化提取磷酸的工艺。系统考察三烷基胺(N235)浓度、萃取温度、相比、振荡时间等因素对萃取率的影响,并用McCabe-Thiele图解法预测理论阶段数,结果表明在相比为O/A=2的三个理论阶段后,98%以上的H_(2)SO_(4)将被去除。设计了一系列串级实验进行三级逆流萃取模拟,得到H_(2)SO_(4)的萃取率为95.40%,H_(3)PO_(4)的萃取率仅为3.33%。结果表明该体系对硫酸具有较高选择性,可实现H_(3)PO_(4)与H_(2)SO_(4)的高效分离。通过机理研究可知,萃取配合物以H_(2)SO_(4)·2[N235]形式存在,H_(2)SO_(4)通过与N235形成离子对络合物被萃取进入有机相中。

湿法磷酸萃取技术发展现状与研究进展

磷酸作为一种重要的化工原料,在化工业中占有极其重要的地位.磷酸的应用主要由磷酸的纯度决定,低纯度磷酸可用于工业和农业领域,而高纯度磷酸则可用于医药、食品和电子等行业.我国磷矿以低品位磷矿为主,生产磷酸主要采用湿法工艺.相比热法生产,湿法工艺更加清洁环保,但产品杂质含量多、种类复杂,故发展磷酸净化技术尤为重要.本文从湿法磷酸纯化技术中的萃取法出发,综述了萃取法的主要研究进展.重点介绍了溶剂萃取法、双水相萃取法、反胶团萃取法、超声协助萃取法和超临界流体萃取法的基本原理和发展趋势.分析了不同萃取方法的优缺点、分离效果和适用条件.突出介绍了溶剂萃取法,梳理了磷酸除杂的主要萃取剂,特别强调了复合萃取剂和新型萃取剂在磷酸纯化方面的显著优势,最后,对磷酸的萃取技术做出了前景展望.

有机溶剂萃取制精制磷酸中氟含量的测定研究

根据测定有机溶剂萃取制精制磷酸过程中各种酸和酯的氟含量的要求,对行业标准《工业湿法净化磷酸》(HG/T 4069—2008)中氟含量的测定方法进行了优化,调整了试样取样量和所配制氟标准溶液的浓度,并进行了试验验证。结果表明:在保证测定结果准确度的条件下,优化后的方法扩大了氟含量的测定范围,相对标准偏差为1.92%~2.76%,可满足有机溶剂萃取制精制磷酸过程中对氟含量的测定要求。

萃取法净化湿法磷酸工艺中杂质系数的研究

采用自制的萃取剂对湿法磷酸预处理酸进行萃取,洗涤萃取酸后对其进行反萃取,分别测定了预处理酸、不同次数萃取和反萃取后所得的萃余酸、洗涤酸及反萃酸的杂质系数,并分析了杂质系数的变化规律。结果表明:杂质系数由小到大依次为反萃酸、洗涤酸、萃余酸;经脱硫处理的预处理酸的杂质系数大于不脱硫处理的;萃余酸的杂质系数越大,说明萃取剂对金属杂质元素的选择性越强,萃取剂的表现越好。

湿法磷酸萃取尾气中氟回收的改造措施

简述了湿法磷酸萃取尾气洗涤系统降低氟含量的改造措施。

磷酸装置浓密机底流提浓技改

针对某磷酸装置原浓密机产能不足及底流固含量低的问题,阐述了浓密机的工作原理和磷矿颗粒的沉降过程,分析了影响浓密机底流固含量的相关因素,根据磷矿浆沉降实验得到的参数,优化了浓密机结构尺寸和相关参数,投资新增了一台大尺寸浓密机,不仅满足了磷酸萃取的产能需求,提高了底流固含量,且每年可节约成本1 667万元,取得较好的经济效益。

Solid-phase extraction and separation of indium with P_(2)O_(4)-UiO-66-MOFs (di-2-ethylhexyl phosphoric acid-UiO-66-metal-organic frameworks)

Compared with the traditional liquid–liquid extraction method,solid-phase extraction agents are of great significance for the recovery of indium metal due to their convenience,free of organic solvents,and fully exposed activity.In this study,P_(2)O_(4)(di-2-ethylhexyl phosphoric acid)was chemically modified by using UiO-66 to form the solid-phase extraction agent P_(2)O_(4)-UiO-66-MOFs(di-2-ethylhexyl phosphoric acid-UiO-66-metal-organic frameworks)to adsorb In(Ⅲ).The results show that the Zr of UiO-66 bonds with the P-OH of P_(2)O_(4) to form a composite P_(2)O_(4)-UiO-66-MOF,which was confirmed by X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FT-IR).The adsorption process of indium on P_(2)O_(4)-UiO-66-MOFs followed pseudo first-order kinetics,and the adsorption isotherms fit the Langmuir adsorption isotherm model.The adsorption capabilities can reach 192.8 mg/g.After five consecutive cycles of adsorption-desorption-regeneration,the indium adsorption capacity by P_(2)O_(4)-UiO-66-MOFs remained above 99%.The adsorption mechanism analysis showed that the P=O and P-OH of P_(2)O_(4) molecules coated on the surface of P_(2)O_(4)-UiO-66-MOFs participated in the adsorption reaction of indium.In this paper,the extractant P_(2)O_(4) was modified into solid P_(2)O_(4)-UiO-66-MOFs for the first time.This work provides a new idea for the development of solid-phase extractants for the recovery of indium.

Extraction of germanium(IV) from acid leaching solution with mixtures of P204 and TBP

Solvent extraction experiments were conducted from acidic solutions containing germanium（IV） and other metal ions, such as Ga3＋, Fe3＋, Zn2＋ and Fe2＋ in hydrometallurgical process of zinc. The purpose of this work was to enhance the efficiency of the extraction and stripping processes and the selectivity of germanium and other metals, while making the method as simple as possible. Germanium was recovered from sulfuric acid, using di-（2-ethylhexyl） phosphoric acid （P2O4） as an extractant, tributyl phosphate （TBP） as modifier diluted in sulfonate kerosene and stripped by NaOH aqueous solution. Extraction studies were carried out under different acid concentrations and solvent concentrations, and optimized conditions were determined. The numbers of stages required for extraction and stripping of metal ions were determined from the McCabe-Thiele plot. The results show that the extracting and stripping efficiencies are 94.3% and 100%, respectively, through two-stage extraction and two-stage strip. Moreover, the synergistic effect of TBP on the system P2O4/kerosense/Ge4＋ is revealed with respect to the extraction of germanium.

Solvent extraction of rare earth ions from nitrate media with new extractant di-(2,3-dimethylbutyl)-phosphinic acid

As a relatively new extractant, di-（2,3-dimethylbutyl）-phosphinic acid （HYY-2） is more efficient to separate heavy rare earths Tm/Yb/Lu than Cyanex 272 and P507. In this paper, HYY-2 was synthesized in our lab, and the extraction equilibrium, thermodynamics and stripping acidity for La, Gd and Y, which stood for light rare earth elements （REE）, middle REE and heavy REE respectively, from nitrate media with this extractant were investigated. Meanwhile, extraction ability, capacity and stripping acidity of HYY-2 were investigated and compared with those of Cyanex 272 and P507. The separation performance for rare earth element couples Gd/Eu and Er/Y were also studied. Compared to Cyanex 272, it possessed higher extraction capacity; while compared with P507, it has lower stripping acidity. The maximum βGD/Eu 1.46 occurred at PHequilibrium=2.78 and the maximumβEr/Y was 1.47 when pHequilibrium= 2.01.

Solvent extraction of zinc from zinc sulfate solution

The extraction of zinc from zinc sulfate solution was investigated, using 20% saponified D2EHPA as an extractam and 260^# sulfonate kerosene as a diluent. The solution was stirred for 8 min at phase ratio （Vσ/Va） of 1.0：1.0, initial pH of 2.0 and stirring speed of 200 r/min. The results show that 75% zinc can be extracted from the zinc sulfate solution when the concentration of zinc is 18.7 g/L after being settled for 10 min. 88.60% zinc can be stripped by 196 g/L sulfuric acid, and zinc ion can be separated from ferric ion.