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1.
《分离科学与技术》2012,47(14):2196-2203
The transport behavior of Nd (III) through a supported liquid membrane (SLM) containing PTFE as support with organophosphorus extractant dinonyl phenyl phosphoric acid (DNPPA) carrier has been studied. The effect of neutral donors such as TOPO (tri-n-octyl phosphine oxide) TBP (tri-n-butyl phosphate), TEHP (tris 2-ethylhexyl phosphate) and Cyanex 923 (a mixture of four trialkyl phosphine oxides) in combination with DNPPA on transport of Nd (III) from HCl across SLM has been examined and the following trend was observed: TOPO > Cyanex 923 > TBP > TEHP. The effect of experimental variables such as feed acidity (0.5 to 5 M HCl), neodymium metal ion concentration (6.94 × 10?4 to 6.94 × 10?3 M), DNPPA concentration (0.2 to 0.6 M), stripping reagents in the receiving phase on Nd (III) transport across SLM were investigated. The percentage transport of Nd (III) was 97% after 6 hr run with 0.6 MDNPPA + 0.13 MTOPO as carrier. The permeability of Nd (III) decreased with increase in HCl and Nd (III) concentration in the feed solution. The transport of Nd (III) decreased with increase in membrane thickness as well as with decrease in pore size. Under optimized conditions transport behavior of other rare earths was also investigated independently, the trend observed was: La > Pr ≥ Nd > Sm > Eu > Gd > Tb > Dy > Ho > Er > Tm > Lu ≥ Y. 相似文献
2.
《分离科学与技术》2012,47(4):592-600
The permeation of U(VI) from nitric acid medium using supported liquid membrane (SLM) technique has been studied employing varying compositions of feed (uranium concentration and acidity), carrier, and receiving phase. Microporous polytetrafluoroethylene (PTFE) membranes were used as a solid support and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A) either alone or as a mixture of neutral donors like tri-n-butyl phosphate (TBP), tris(2-ethylhexyl) phosphate (TEHP), and tri-n-octyl phosphine oxide (TOPO) dissolved in n-parrafin as the carrier. Oxalic acid/Na2CO3 solutions were used as the receiving phase. The permeability coefficient (P) of U(VI) decreased with increased nitric acid concentration up to 3 M HNO3 and thereafter increased up to 5 M HNO3. Uranium permeation was also investigated from its binary mixtures with other metal ions such as Zr(IV), Th(IV), and Y(III) at 2 M HNO3 employing 0.1 M PC88A/n-paraffin as the carrier, and 0.5 M oxalic acid as the receiver phase. The presence of neutral donors in the carrier solution enhanced the permeation of U(VI) across the SLM in the following order: TEHP ~ TBP > TOPO using 0.1 M oxalic acid as receiver phase. There was significant enhancement in uranium transport for feed acidity ≤2 M HNO3 employing 1 M Na2CO3 as the receiver phase. These studies suggested that 0.1 M PC88A and 0.5 M oxalic acid as carrier and receiver phases appear suitable for selective and faster transport of uranium from the uranyl nitrate raffinate (UNR) waste solutions. 相似文献
3.
《分离科学与技术》2012,47(13):2013-2019
Separation of U(VI) from Th(IV) and rare earth elements (REEs) present in monazite leach solution (nitric acid medium) has been studied using tris(2-ethylhexyl) phosphate (TEHP) and tri-n-butyl phosphate (TBP) dissolved in n-paraffin as solvents under varying experimental conditions such as nitric acid, extractant and metal ion concentrations etc. There is an increase in distribution ratio of U(VI) (D U ) with increase in aqueous phase acidity up to 5 M HNO3 beyond which a decrease is observed. Typically for 1 × 10?3 M U(VI), the DU values increase from 8 (0.5 M HNO3) to 80 (5 M HNO3) for 1.1 M TEHP, and from 2 (0.5 M HNO3) to 43 (5 M HNO3) for 1.1 M TBP in n-paraffin. The separation factors of U(VI) (β: DU/DM) over metal ions (M) such as Th(IV) and Y(III) (chosen as a representative of heavy REEs) are better for TEHP than TBP at all nitric acid concentrations. Batch solvent extraction data have been used to construct the McCabe-Thiele diagrams for the recovery of U(VI) employing TEHP as the extractant. A process flow sheet has been proposed with 0.2 M TEHP in n-paraffin as solvent for the recovery of U(VI) from simulated monazite leach solution in HNO3 medium. 相似文献
4.
Present studies deal with the application of supported liquid membrane (SLM) technique for the separation of uranium (VI) from phosphoric acid medium using a binary mixture of 2-ethyl hexyl phosphoric acid-mono-2-ethyl hexyl ester (PC88A) and neutral donor which is a mixture of four tri-alkyl phosphine oxide better known as Cyanex 923 in n-dodecane as a carrier and (NH4)2CO3 as a receiving phase. Various parameters like feed acidity, nature of strippant, carrier concentration, membrane pore size, membrane thickness etc. which affect the transport of U(VI) have been studied in detail. Experiments have also been carried out to see the transport behaviour of different fission products from a diluted High Level Waste (HLW) solution. Stability of the membrane against the leaching of the extractant and stability of the membrane support have also been investigated. We have tried to model the physicochemical transport of U(VI) in SLM as well as establishing the mechanism (Diffusion controlled) of transport. More than 95% uranium (VI) is recovered in 360 min using a binary mixture of 0.60 M PC88A and 0.15 M Cyanex 923 in n-dodecane as carrier and 0.5 M (NH4)2CO3 as stripping phase from the 0.5 M H3PO4 feed. Lower concentration of H3PO4 (0.5 M) and optimum carrier concentration (0.60 M PC88A + 0.15 M Cyanex 923) in the mole ratio of 4:1 is found to be the most suitable condition for maximum transport of uranium (VI). The optimum conditions obtained from this study was also applied to recover uranium from analytical waste in phosphoric acid medium generated in the laboratory. 相似文献
5.
《分离科学与技术》2012,47(14):2179-2187
Solvent extraction and supported liquid membrane (SLM) transport properties of Eu(III) from nitric acid feed conditions were investigated using several substituted diglycolamide (DGA) extractants such as N,N,N′N′-tetra-n-octyl diglycolamide (TODGA), N,N,N′N′-tetra(2-ethylhexyl) diglycolamide (T2EHDGA), N,N,N′N′-tetra-n-hexyl diglycolamide (THDGA), N,N,N′N′-tetra-n-pentyl diglycolamide (TPDGA), and N,N,N′N′-tetra-n-decyl diglycolamide (TDDGA). Effects of feed acidity and phase modifier composition on Eu(III) extraction were investigated using the DGAs and the nature of extracted species were ascertained by slope analysis method. The Eu(III) distribution ratio (DEu) values were found to decrease in the presence of iso-decanol. In general, the DEu values decreased with increased alkyl chain length of the DGA. The extracted species contained only 2 extractant molecules when TPDGA and TDDGA were used while for TODGA about four extractant molecules were found to be present in the extracted species. The supported liquid membrane transport of Eu(III) was studied under varying experimental conditions using the five DGA extractants. Transport studies using 0.1 M DGA as the extractant suggested the trend as TDDGA > TODGA > T2EHDGA ~ THDGA which significantly changed to TPDGA > THDGA > TODGA > TDDGA > T2EHDGA in the presence of 30% iso-decanol as the phase modifier. The permeability coefficient (P) values were also determined with membranes of varying pore sizes. 相似文献
6.
《分离科学与技术》2012,47(3):480-486
The extraction of uranium (VI) from 5.3 mol.L?1 phosphoric acid with a series of phosphoric, phosphinic, dithiophosphoric, or dithiophosphinic acid derivatives (0.5 mol.L?1) in mixture with 0.125 mol.L?1 TOPO in Isane IP 185 has been investigated. In the frame of the present work, eight acidic phosphorus and thiophosphorus compounds have been synthesized: bis(1,3-diisobutoxypropan-2-yl) phosphoric acid, bis(1,3-bis-(butylthio)propan-2-yl) phosphoric acid, bis(5,8,12,15-tetraoxanonadecan-10-yl) phosphoric acid, bis(1-butoxyheptan-2-yl) phosphoric acid, bis(undecan-6-yl) phosphoric acid, bis(2-(1,3-dibutoxypropan-2-yloxy)ethyl) phosphoric acid, bis(3-butoxy-2-(butoxymethyl)-2-methylpropyl) phosphinic acid, bis(1,3-dibutoxypropan-2-yl) dithiophosphoric acid. The properties of these molecules in mixtures with TOPO have been compared with those of other extractants such as bis(2-ethylhexyl) phosphoric acid, bis(2-ethylhexyl) dithiophosphoric acid, bis(2-ethylhexyl) phosphinic acid, Cyanex® 272, and Cyanex® 301. The replacement of phosphoric acid-type extractant by their phosphinic homologues dramatically decreases the affinity for uranium (VI) whereas the replacement of the phosphoric and phosphinic acid-type extractants by their dithio homologues affects positively the distribution coefficient of uranium (VI). It also appears that the steric hindrance effect is responsible for a significant decrease of the distribution coefficient of uranium (VI). Supplemental materials are available for this article. Go to the publisher's online edition of Separation Science and Technology to view the free supplemental file. 相似文献
7.
《分离科学与技术》2012,47(6):959-964
The interfacial behavior of Cyanex 272 has been investigated using the Du Nouy ring method. Different adsorption isotherms such as the Gibbs and Szyszkowski isotherms have been found as fitting well to the experimental data. The values of interfacial excess at the saturated interface increase in the following order: n-heptane > cyclohexane > CCl4 > toluene > benzene > chloroform, explained according to the stronger solution effect of aromatic hydrocarbon. The effects of temperature, acidity, and ionic strength of the aqueous phase on the interfacial activity of Cyanex 272 are also examined and explained in detail. Moreover, the reaction orders against Cyanex 272 predicted from the interfacial tension isotherms are in agreement with the order determined experimentally, which suggests that the interfacial activity of Cyanex 272 can provide enough strong evidence quantitatively supporting the interfacial mechanism. 相似文献
8.
膦(磷)类萃取剂浸渍树脂吸附重稀土的性能 总被引:1,自引:0,他引:1
利用静态法研究了5种不同膦(磷)类萃取剂的浸渍树脂在盐酸介质中对重稀土的吸附行为. 结果表明,Cyanex272与膦(磷)类萃取剂组成的双萃取剂的浸渍树脂在同等实验条件下比单一Cyanex272萃取剂的浸渍树脂对重稀土具有更好的吸附性,其中以Cyanex272与P507, Cyanex302, Cyanex923和TBP分别按体积比1:1, 5:1, 1:1, 2:1混合为最优. 吸附最佳pH值在3.0~4.0之间,吸附平衡时间为50 min,升高温度对吸附有利. 在相同实验条件下,5种浸渍干树脂Cyanex272, Cyanex272-P507, Cyanex272-Cyanex302, Cyanex272-Cyanex923, Cyanex272-TBP对重稀土的饱和吸附容量分别为20.04, 25.37, 21.87, 22.16, 38.48 mg/g. 相似文献
9.
《分离科学与技术》2012,47(3):549-572
Abstract The extraction of Ge(IV) from HCl, HNO3 and H2SO4 media in toluene solution of Cyanex 301 and Cyanex 923 is investigated. It is almost quantitatively extracted (~95%) in Cyanex 301 and Cyanex 923 at 8 molL?1 HCl but the extractions from H2SO4 and HNO3 are poor in the entire investigated range of acid molarity. Detailed investigations were carried out from HCl medium. Based on the slope analysis data the extracting species is identified as GeCl4·2R (R=Cyanex 301/Cyanex 923). The extraction of Ge(IV) is higher and comparable in diluents like toluene, n‐hexane and kerosene (160–200°C) and there is no correlation between the dielectric constant and the percent extraction. The extractants are stable towards prolonged acid contact and there is negligible loss in their extraction efficiency even after recycling them for several cycles. The extraction behavior of commonly associated metal ions namely As(V)/(III), Sn(IV), Tl(III), In(III), Ga(III), Fe(III), Al(III), Hg(II), and Cu(II) has also been investigated. Based on the partition data conditions for attaining some binary and ternary separations involving Ge(IV) have been optimized. The separation data have been fused to develop a scheme for the recovery (93%) of pure germanium (~99%) from semi conductor waste. 相似文献
10.
ABSTRACT The extraction behaviour of 1M solutions of tri-2-ethylhexyl phosphate (TEHP), di-2-ethyl hexyl isobutyramide (D2EHIBA), tri-n-butyl phosphate (TBP) and di-n-hexyl hexanamide (DHHA) in n-dodecane towards U(VI), Th(IV) and Pa(V) in the presence of 220 g/L of Th from nitric acid medium has been studied. The limiting organic concentrations (LOC) of thorium (g/L) for 1 M TBP and 1 M DHHA are evaluated as 31, 20 ( at 1 M HNO3) and 25,13 (at 4 M HNO3) respectively. The distribution ratio (D) values of U(VI), Th(IV) and Pa(V) in the presence of thorium (220 g/L) at. 1 M HNO3 suggest that branching in the alky group of amides suppresses the extraction considerably. In view of the selective extraction of U over Th by 5 % TBP in THOREX process at 4 M HNO3, distribution behaviour is also studied employing a lower concenfration (0·18 M) of extractant for comparison purpose, Separation factor (S. F.) values for U(VI) over Th(IV) under different experimental conditions consistently varied in the order: D2EHIBA > DHHA > TEHP > TBP. The quantitative extraction of 233U from a synthetic mixture containing 233U (10?5 M). 233Pa (10?11 M) and thorium (220 g/L) at 1 M HNO3 using 1 M solution of D2EHIBA in n-dodecane is achieved in three stages, Stripping and reusability studies of D2EHIBA have also been carried out. 相似文献
11.
Abstract The extraction of lanthanum(III) and samarium(III) from nitrate solutions by some phosphine oxide compounds (Cyanex 921, Cyanex 923, and Cyanex 925) in kerosene was investigated. The influence of the different factors affecting the extraction was studied in detail. The extraction of these metals using the above extractants was compared and the sequence of extraction was found to be Cyanex 921>Cyanex 923?Cyanex 925. The stripping percent of La(III) and Sm(III) by 0.75 M HNO3 from the loaded organic phase after two stages were 72% and 5.2%, respectively, which could enable a good separation between these two lanthanides. 相似文献
12.
The extraction of indium from a synthetic sulfate‐containing solution using commercial reagents (Cyanex 272, DEHPA, and Cyanex 923) is evaluated on a comparative basis. The extraction profiles of indium (III) were examined with regard to the reagent concentration, the pH value of the aqueous solution, and the indium concentration in a low phase ratio of 1:10. DEHPA and Cyanex 272 are, in contrast to Cyanex 923, very well suited for the extraction of indium. Re‐extraction with HCl and H2SO4 is compared. 相似文献
13.
《分离科学与技术》2012,47(7):997-1005
The equilibrium study on reactive extraction of picolinic acid by six different extractants (phosphoric and aminic) dissolved in two different diluents (benzene and decane-1-ol) is carried out to evaluate the performance of extractants and diluents. The extraction ability in terms of the distribution coefficient (K D) is found to be in the order of tri-n-octylamine (TOA) ≥ tri-n-dodecylamine (TDDA) > di-2-ehylhexyl phosphoric acid (D2EHPA) > tri-n-butyl phosphate (TBP) > tri-octyl methyl ammonium chloride (Aliquat 336) > tri-n-octyl phosphine oxide (TOPO) with both diluents. Decan-1-ol is found to be the better solvating medium for the acid-extractant complexes. A mathematical model based on mass action law is employed to estimate the values of partition coefficient (P) and dimerization constant (D) in physical extraction, and equilibrium extraction constants (K E) in chemical extraction. The values of loading ratios (Z) less than 0.5 imply the formation of (1:1) acid:extractant solvates in the organic phase. Decan-1-ol with TOA is the most effective solvation medium with K D, max = 9 at 0.01 kmol · m?3 of picolinic acid and K E = 19.448 m3 · kmol?1. 相似文献
14.
《分离科学与技术》2012,47(8):1112-1120
The transport behavior of Th4+ was investigated from a feed containing 3.0 M HNO3 into a receiver phase containing 0.1 M oxalic acid across a PTFE flat sheet supported liquid membrane (SLM) which contained TODGA (N,N,N′,N′-Tetraoctyl-3-oxapentanediamide) in n-dodecane as the extractant. Effects of the nature of the strippant, extractant concentration, Th concentration in the feed, and feed acidity on the transport rates were investigated. The transport behavior apparently depended on the rate of extraction of the metal ion at the feed-membrane interface and was not diffusion controlled. Influence of Th concentration on flux was also investigated. Transport mechanism was elucidated and the diffusion coefficient was calculated to be 2.13 × 10?7 cm2/s. Solvent extraction studies at varying feed acidity and TODGA concentration were also carried out. 相似文献
15.
《分离科学与技术》2012,47(6):824-831
This paper deals with studies on the extraction of uranium(VI) from phosphoric acid medium using (2-ethylhexyl)phosphonic acid mono 2-ethylhexyl ester and tri-n-octylphosphine oxide individually as well as from their synergistic mixture. Different extraction parameters were investigated. With an increase in phosphoric acid concentration in the aqueous phase, the distribution ratio (Du) was found to decrease in all the cases. Synergism was observed when a mixture of PC-88A and TOPO was used. The synergistic mixture in the mole ratio of 4:1 (1.80 M PC-88A: 0.45 M TOPO) in xylene was found to be most suitable for uranium extraction. Among the various strip liquors used, 5% (w/v) solution of (NH4)2CO3 was found to be the most suitable. Using a mixture of 1.8 M PC-88A and 0.45 M TOPO as the extractant system and 0.5 M ammonium carbonate as the stripping agent, uranium recovery was found to be better than 97% ± 3% in multiple contacts, (n = 2) from actual Davies Gray Waste while in case of wet phosphoric acid more than 52% ± 3% (n = 3) only could be recovered where n is the number of contacts. 相似文献
16.
John S. Preston Anna C. du Preez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1997,69(1):86-92
The solvent extraction of uranium(VI) and thorium(IV) from sodium nitrate solutions (0·20–6·00 M ) by a series of dialkyl sulphoxides with different structures was studied. For sulphoxides with n-alkyl groups (R2SO, where R = n-hexyl, n-octyl and n-decyl) using 0·20 M solutions in xylene, the extractions of both uranium and thorium are relatively high, and the values of the separation factor βThU are correspondingly low (≈20). Replacement of an n-hexyl group by a cyclohexyl group has little effect on metal extraction, whilst the introduction of a second cyclohexyl group causes a slight decrease in extraction. Similarly, there is little variation in the extraction of uranium and thorium through the series of asymmetrical compounds RR′SO, where R = n-octyl and R′ = cyclopentyl, cyclohexyl or cyclooctyl. When two aromatic (phenyl) rings are introduced into the sulphoxide, however, the extraction of both metals falls to zero. For the series of isomeric compounds R2SO with C8 alkyl groups, the separation factors increase in the order: R = n-octyl, 2-ethylhexyl, 2-octyl, 3-octyl, which is also the order of increasing steric bulk of the alkyl group. For these compounds, slope analysis studies are consistent with the formulation of the extracted metal complexes as UO2(NO3)2(R2SO)2 and Th(NO3)4(R2SO)3. © 1997 SCI. 相似文献
17.
In this work, bulk-liquid membrane (BLM) system is used to compare tri-n-butyl phosphate (TBP), tri-isoamyl phosphate (TiAP), and tris(2-ethylhexyl) phosphate (TEHP) for their relative ability to co-extract U(VI) and nitric acid from aqueous nitric acid feed-phase into water strip-phase, through hydrocarbon membrane-phase. The kinetics of extraction is modelled and the model is validated through experiments. The quantity which determines the efficiency of liquid emulsion membrane (LEM) process is the relative rate of extraction of U(VI) to nitric acid. This is in the order TiAP>TEHP>TBP, indicating that TiAP is most suitable for extraction of U(VI) from nitric acid using LEM. 相似文献
18.
《分离科学与技术》2012,47(12):2573-2584
Abstract Tris(2-ethylhexyl)phosphate (TEHP) dissolved in toluene is used for selective extraction of vanadium(V) and niobium(V) from hydrochloric and hydrobromic acid solution. Vanadium is determined spectrophotometrically after backextraction from TEHP, whereas unstripped niobium is determined in the TEHP phase with thiocyanate. The probable extractable species is VOCl3·2TEHP or NbOCl3·2TEHP/NbOBr3·2TEHP. The method permits mutual separation of vanadium(V), niobium(V), and tantalum(V), and provides analysis of vanadium and niobium in alloys with a high degree of accuracy and precision. 相似文献
19.
Li Cui Kun Jiang Junfeng Wang Kun Dong Xiangping Zhang Fangqin Cheng 《American Institute of Chemical Engineers》2019,65(8):e16606
The solvent extraction of Li+ by Cyanex 923 was investigated upon the addition of different imidazolium-based ionic liquids (ILs). The results showed 1-hydroxylethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HOEmim][NTf2]) can improve the extraction of Li+ most effectively. The fundamental mechanism is that [HOEmim][NTf2] can remarkably enhance the coordination ability of Cyanex 923 to Li+ to form more stable and hydrophobic ion-pair species [Li(Cyanex 923)n][NTf2] (nmax = 3) resulting from the electrostatic interaction and typical hydrogen bonding of IL, and thus facilitating the transfer of Li+ into organic phase. This work has revealed the transfer mechanism of Li+ in a solvent extraction system comprising of IL and neural ligand. The knowledge of the coordination environment of Li+ in the presence of IL also gives us a new insight into the separation of 6Li/7Li. The disadvantage of this process is the loss of IL. However, this study provides guidance for the design of better IL-based systems for the separation of metal ions. 相似文献
20.
《分离科学与技术》2012,47(4):554-561
Solvent extraction studies on Sr2+ and Y3+ are carried out from varying concentrations (0.01–6.0 M) of nitric acid using di-(2-ethylhexyl)phosphoric acid (D2EHPA) as extractant. Extraction of yttrium is observed to be higher than that of strontium at all the acidities and is found to increase substantially with decreasing concentration of nitric acid. Practically negligible extraction (D < 10?3) of Sr2+ is observed from feed solutions containing nitric acid in the range of 1.0 to 4.0 M. These solvent extraction data are used to optimize the transport of 90Sr and 90Y across the supported liquid membrane (SLM) individually as well as from their mixture (due to insitue growth) under different experimental conditions. Selective separation of 90Y (>90%) from 90Sr is obtained in 6 h, when the concentration of nitric acid in feed is kept at 1.0 M and that of receiving phase is maintained at 4.0 M. 20% D2EHPA in n-dodecane is found to be the optimum carrier concentration for the efficient transport of 90Y in SLM mode. Under these conditions transport of strontium is found to be negligible. Radiochemical purity of the product 90Y is checked by following its decay as well as by extraction paper chromatography. The contamination of 90Sr in 90Y product is found to be < 0.001%. Based on the experimental results, a single stage SLM system for the generation of carrier-free 90Y from 90Sr source is described. The system is amenable for automation and scale up. 相似文献