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.     

Recovery of rare earths from spent FCC catalysts by solvent extraction using saponified 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(EHEHPA)

A process to recover rare earth(RE) metals from spent fluid catalytic cracking(FCC) catalysts by solvent extraction was studied, using saponified 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(EHEHPA or P507). The recovery process involved three steps:(1) leaching REs(mainly lanthanum and cerium);(2) solvent extraction by applying saponified P507-kerosene system;(3) stripping. Experiments to assure optimal operating conditions were conducted. Results indicated that RE metals could be recovered effectively from spent catalyst with saponified P507-kerosene-HCl system. At room temperature of 25 oC, 10 g spent catalyst with 110 m L of HCl(1 mol/L) could achieve a leaching efficiency of 85%. For extraction, initial pH value of 3.17, organic/aqueous ratio(O/A ratio) of 2:1 with an extractants' saponification rate of 20% could obtain 100% efficiency. In the stripping process, 1 mol/L HCl with O/A ratio of 1:1 led to a stripping efficiency of 96%. In the present study, RE metals from spent FCC catalysts were effectively recovered, which avoided wasting a large amount of RE resources. It provides a theoretical support for commercial recycling of RE resources.     

Synergistic extraction of cerium from sulfuric acid medium using mixture of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester and Di-（2-ethyl hexyl） phosphoric acid as extractant

Synergistic extraction of cerium(IV) from sulfuric acid medium using mixture of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester(HEH/EHP, HL) and Di-(2-ethyl hexyl) phosphoric acid (HDEHP, HA) as extractant was investigated. The results indicated that the maximum synergistic enhancement coefficients were obtained at the mole fraction of HEH/EHP=0.6, and cerium(IV) was extracted into organic phase in the form of Ce(SO4)0.5HL2A2. A cation exchange mechanism was proposed for the synergistic extraction of Ce(IV). The equilibrium constants and thermodynamic functions such as △G, △H, and △S were determined in the extraction of Ce(IV) from sulfuric medium using mixture of HEH/EHP and HDEHP.     

Separation of molybdenum from tungsten by di-2-ethylhexyl phosphoric acid extractant

The efficiency of extracting molybdenum(VI) from a weakly acidic solution containing a large amount of tungsten and a small amount of molybdenum using di-2-ethylhexyl phosphoric acid (D2EHPA) is low. However, when ethylenediaminetetraacetic acid (EDTA) complexing agent is present, the efficiency of molybdenum extraction is significantly increased. In this paper the effect of various factors (including the D2EHPA and EDTA concentration, pH of the feed solution, contact time, phase ratio) on molybdenum extraction has been studied. The effect of the composition of the strip solution on stripping molybdenum from the organic phase is reported. Counter-current extraction has also been investigated. The results of multiple-stage extraction show that molybdenum can be satisfactorily separated from sodium tungstate solution obtained by leaching tungsten ore, with little loss of tungsten. A possible mechanism of the extraction of molybdenum in the presence of EDTA is discussed. The reaction for extracting molybdenum is:

     

甲基磺酸亚铈催化合成柠檬酸三(2-乙基)己酯的研究

合成了甲基磺酸亚铈,研究了以甲基磺酸亚铈催化柠檬酸和2-乙基己醇的酯化反应,考察了反应温度、催化剂用量、醇酸摩尔比等因素对反应结果的影响,对合成的产品进行了红外光谱分析.实验结果表明,甲基磺酸亚铈催化合成柠檬酸三(2-乙基) 己酯的最佳反应条件为:n (2-乙基己醇):n(柠檬酸)＝3.60:1,催化剂用量0.25% (以酸的物质的量计),反应温度120℃～130℃,负压操作.在最佳反应条件下,柠檬酸三(2-乙基)己酯收率在98.0%以上.反应结束后,催化剂通过简单的相分离即可重复使用.甲基磺酸亚铈重复使用5 次后,其催化活性无明显下降,产品收率仍可达到90%以上.     

Solvent extraction of Pr and Nd (III) from chloride-acetate medium by 8-hydroquinoline with and without 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester as an added synergist in heptane diluent

In this paper, solvent extraction of Pr (III) and Nd (III) using 8-hydroxyquinoline in chloride-acetate medium has been systematically investigated. The effect of various parameters, such as equilibrium time, aqueous pH, extractant concentration, acetate ion concentration, chloride ion concentration, and organic solvent, on the extraction has been discussed. The synergistic effect in the mixtures of 8-hydroxyquinoline (HQ) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507) has been explored, and the largest synergistic enhancement factor has been calculated. The separations of Pr (III), Nd (III) and La (III) by 8-hydroquiloline alone and by mixtures of HQ and P507 have been studied, and the results demonstrate that it is possible to separate Pr (III), Nd (III) and La (III) with the mixtures of HQ and P507. At last, the stripping of Pr, Nd and La (III) has been performed.     

Separation of middle rare earths by solvent extraction using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant

The extraction of the trivalent middle rare earths from chloride media by kerosene solutions of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant was studied. The separation factors between the elements using solution simulating wastes from NiMH spent batteries have been evaluated: the order of the extractive ability of extractant can be confirmed in ThGdEuSm.     

Studies on the effects of orally administered Di-(2-ethylhexyl) phthalate in the ferret

N,N'2-2,7-Flourenylenebisacetamide (2.7-FAA) was administered orally to 34 female, strain AXC/I rats. Nineteen were pretreated with the extirpation of the salivary glands. The remaining 15 rats received no surgical treatment. Six of these 15 unoperated rats developed mammary carcinomas and seven developed tumors at other sites, whereas none of 19 operated rats had mammary tumors but 8 rats had tumors at other sites. No tumor developed in 4 operated control rats that were on normal diet. The results demonstrate that pretreatment with extirpation of the salivary glands inhibited mammary tumor induction in rats by 2,7-FAA although it did not inhibit induction of other type tumors. The mechanism by which induction of mammary tumors was inhibited is not clear. Ovarian atrophy and hepatic necrosis were observed in both operated and unoperated rats ingesting 2,7-FAA but did not seem to affect carcinogenesis by the carcinogen. Lower body weight was observed in operated rats but it is not considered to be the major cause of a complete inhibition of mammary tumor induction.     

The solvent extraction of lead from chloride solutions using di(2-ethylhexyl)phosphoric acid

Lead has been extracted from chloride solutions into kerosene containing excess di(2-ethylhexyl)phosphoric acid, using various concentrations of metal and extractant. Extraction proceeded readily, but the results indicated that 1.6 hydrogen ions were exchanged per atom of lead extracted, rather than 2.0 as would be expected for a divalent metal ion. Extraction was unaffected by metal concentration over the range studied (0.1–1.0 g l^?1), and the results were highly consistent. The unique log D vs. pH relation allowed simple collection of data for contact stage evaluation by rearrangement of the familiar solvent extraction equations and use of empirically derived constants. An S-shaped extraction isotherm resulted, which limits the ease with which aqueous lead concentrations may be reduced by extraction with di(2-ethylhexyl)phosphoric acid.     

The separation of zinc from copper by di-2-ethylhexyl phosphoric acid - an equilibrium study

The extraction of copper and zinc from sulphate media by di-2-ethylhexylphosphoric acid (D2EHPA) is reported. The equilibrium data for the extraction of (1) zinc alone (2–40 g/l), and (2) copper alone (2–60 g/l) by both 10 v/v % and 20 v/v % D2EHPA are given.The general case of extraction of two metals which compete for the same extractant is considered, and the data for the binary metal system zinc/copper extracted by 20 v/v % D2EHPA are reported. Specific chemical models and empirical models have been developed to correlate the data.Because the extractant has a high affinity for zinc in the presence of copper, the binary data can be modelled on the assumption that the interaction of copper with zinc can be neglected. However, the effect of zinc in reducing the extraction of copper is significant.We show that zinc can be decontaminated from copper and test the predictions with a laboratory scale counter current apparatus. Typical predictions show that in five stages, a 20 v/v % D2EHPA feed and an aqueous feed of 1.98 g/l Zn, 36.78 g/l Cu, zero g/l H₂SO₄ would give a 89.9% recovery of zinc with purity of 90%; with lower copper to zinc ratios in the feed the purity may be improved.     

P204萃取铒的热力学和动力学研究

用含萃取剂P204的磺化煤油对稀土离子Er~（3+）进行萃取平衡研究,得到了萃取平衡式和平衡常数。用恒界面槽测量稀土离子的萃取速率和反萃速率,考察了Er~（3+）浓度、H~+浓度、P204液度和络合物浓度对反应速率的影响,从而得到了反应速率的表达式。提出了界面反模型,用动力学及界面张力实验进行了验证。     

Structure Reactivity Studies on the Extraction of Rare Earths by Di(2-ethylhexyl)chloroalkyl Phosphonates

The extractive separation properties and the extractive regularity of the lanthanide elements by fivedi(2-ethylhexyl)alkyl phosphonates with various alkyl structure:di(2-ethylhexyl)chloromethyl phosphonateCH_2ClP(O) (OC_8H_(17)-i)_2(1),di(2-ethylhexyl)β-chloroethyl phosphonate ClCH_2CH_2P(O) (OC_8H_(17)-i)_2(2),di(2-ethylhexyl)α-chloroethyl phosphonate CH_3CHClP(O)(OC_8H_(17)-i)_2 (3),and correspondingdi(2-ethylhexyl)methyl phosphonate CH_3P(O)(OC_8H_(17)-i)_2 (4),di(2-ethylhexyl)ethyl phosphonateC_2H_5P(O) (OC_8H_(17)-i)_2 (5),in nitrate system have been studied.The coordination compounds were prepared.The structure of these extractants and their coordination compounds were further explored by IR and ~(31)P NMRspectra.     

Oral toxicity of bis(2-ethylhexyl) phthalate during pregnancy and suckling in the Long-Evans rat

Bis(2-ethylhexyl) phthalate (DEHP) is a compound widely used in plastics technology to impart flexibility to rigid polymers. We sought to determine whether the oral exposure of female rats to DEHP during gestation and suckling produces alterations in the litter. Female rats were exposed to different concentrations of DEHP suspended in drinking water (32.5 and 325 microl/litre) from day 1 of pregnancy to day 21 after delivery. Pup body weight gain and kidney, liver and testes weight was measured at different times (21, 28, 35, 42 and 56 days) after birth. Plasma concentrations of DEHP and histopathological alterations in kidneys, liver and testes were also studied. In addition, the ability of female pups (1 month of age) to perform a learned avoidance test, the 'beam walking' test, was evaluated. Perinatal exposure to DEHP produced no statistically significant changes in the body weight gain of offspring. Conversely, it produced a significant decrease in kidney and testes relative weight (organ/body weight) with a significant increase in relative liver weight. Signs of histological damage in kidneys, liver, and particularly testes, were observed. Pups exposed perinatally to the highest concentration of DEHP elicited a significant increase in the time necessary to perform the beam walking test.     

Hepatocarcinogenic potential of di(2-ethylhexyl)phthalate in rodents and its implications on human risk

The plasticizer di(2-ethylhexyl) phthalate (DEHP), to which humans are extensively exposed, was found to be hepatocarcinogenic in rats and mice. DEHP is potentially set free from objects made of synthetic materials (e.g., those used in medicine). Chronically, the greatest amounts are transferred to persons undergoing hemodialysis (up to 3.1 mg/kg b.w. per day) who would thus be considered the individuals most endangered by tumorigenesis. Although toxicokinetics seem to play a certain unclear role in the course of DEHP-related toxicity, toxicodynamic factors appear more decisive. DEHP is a representative of "peroxisome proliferators" (PP), a distinct group of substances that, in rodents, do not only induce peroxisomes but also specific enzymes in other organelles, organ growth, and DNA synthesis. The cluster of the characteristic effects of PP is generally, although perhaps not quite appropriately summarized as "peroxisome proliferation," and is strongest in the liver. The lowest observed effect level (LOEL) and the no observed effect level (NOEL) of peroxisome proliferation in the rat, as determined by the induction of specific enzymes (peroxisomal beta-oxidation, carnitine-acetyl-transferase, cytochrome P-452), DNA synthesis, and hepatomegaly, may be assumed as 50 and 25 mg/kg b.w. per day, respectively. DEHP and other carcinogenic PP are neither genotoxic nor tumor initiators, but they appear to be tumor promoters, also implicating a threshold level for the carcinogenic effect. Although a causal relationship between a particular effect of peroxisome proliferation and hepatocarcinogenesis is as yet unknown, peroxisome proliferation as a whole phenomenon appears to be associated with the potential of tumor induction, as shown by comparison of the relative strength of individual PP and by comparison of species and organ specificities. Likewise, LOEL and NOEL of rodent carcinogenesis, that is, 300 and 50 to 100 mg/kg b.w. per day, respectively, are above but not too far from the corresponding values for the investigated parameters of peroxisome proliferation. Thus, with respect to dose alone, worst-case exposure in hemodialysis patients is at least 16-fold below the LOEL of any characterized PP-specific effect of DEHP and approximately 100-fold below that of DEHP-related tumorigenesis. Also, primates are less responsive to PP than rats with respect to the investigated biochemical and morphological parameters. If this lower primate responsiveness is extrapolated to estimate carcinogenicity in humans, we might thus arrive at an even larger safety margin than when based on exposure alone. Doses of PP hypolipidemics that had clearly induced several indicators of peroxisome proliferation in rats did not cause any clear-cut enhancements in the peroxisomes of patients, even though most of these hypolipidemics were considerably stronger PP than DEHP. Thus, an actual threat to humans by DEHP seems rather unlikely. Accordingly, hepatocarcinogenesis was neither enhanced in workers exposed to DEHP nor in patients treated with hypolipidemics.     

Solvent extraction of cadmium from sulfate solution with di-(2-ethylhexyl) phosphoric acid diluted in kerosene

In the present paper, solvent extraction process has been used for extraction of cadmium from sulfate solution using di-(2-ethylhexyl) phosphoric acid (D2EHPA) with 1% isodecanol in kerosene diluent expected from industrial effluents or leaching of ores/secondary materials. Different process parameters such as pH, contact time, extractant concentration, O/A ratio etc. were investigated. Results demonstrated that quantitative extraction of cadmium was feasible from 4.45 mM cadmium feed solution in single stage at equilibrium pH 4.5, time 2 min and O/A ratio 1:1 with 0.15 mM D2EHPA. The extraction mechanism of cadmium from sulfate solution by D2EHPA in kerosene could be represented at equilibrium by Cd²⁺ + 3/2 (H₂A₂)_org ⇔ CdA₂(HA)_org + 2H⁺. The loading capacity of 0.15 mM D2EHPA in sulfate solution was determined to be ∼ 8.9 mM cadmium. The loaded cadmium was effectively stripped using 180 g/L sulfuric acid. The metal or salt could be produced by electrolysis or crystallization from the stripped solution.