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1.
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
2.
Francisco Jos Alguacil Susana Martínez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(3):298-302
The extraction of zinc(II) by Cyanex 923 (phosphine oxides mixture) in Solvesso 100 from hydrochloric acid solution has been investigated. The extraction reaction is exothermic. The numerical analysis of metal distribution data suggests the formation of ZnCl2·L2,HZnCl3·2L and H2ZnCl4·2L(L = ligand) in the organic phase with formation constants Kext = 4.1,5.6 × 109 and 6.7 × 109, respectively. The results obtained for zinc(II) distribution have been implemented in a solid‐supported liquid membrane system. The influence of source phase stirring speed, membrane composition and metal concentration on zinc transport have been investigated. © 2001 Society of Chemical Industry 相似文献
3.
Ana María Rodríguez Dulce Gmez‐Límn Francisco Jos Alguacil 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(9):967-972
The extraction of cadmium(II) by Cyanex 923 (a mixture of alkylphosphine oxides) in Solvesso 100 from hydrochloric acid solution has been investigated. The extraction reaction is exothermic. The numerical analysis of metal distribution data suggests the formation of CdCl2.2L, HCdCl3.2L and H2CdCl4.2L (L = ligand) in the organic phase. The results obtained for cadmium(II) distribution have been implemented in a solid‐supported liquid membrane system. The influences of feed phase stirring speed (400–1400 min?1), membrane composition (carrier concentration: 0.06–1 mol dm?3) and metal concentration (0.01–0.08 g dm?3) on cadmium transport have been investigated. Copyright © 2005 Society of Chemical Industry 相似文献
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A Bhandare A
P Argekar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(7):811-816
Carrier‐facilitated transport of mercury(II) against its concentration gradient from aqueous 0.1 mol dm?3 hydrochloric acid solution across a flat‐sheet supported liquid membrane (SLM) containing triisobutylphosphine sulfide (Cyanex 471X) as the mobile carrier in kerosene as diluent has been investigated. Dilute sodium thiocyanate solution (0.11 mol dm?3) was the most efficient stripping agent among several aqueous reagents tested. Various parameters such as stirring rate, concentration of HCl in the feed solution, concentration of NaSCN in the strippant, concentration of Cyanex 471X in the membrane, and contact time were investigated. Under optimum conditions the transport of Hg(II) across the liquid membrane is about 100% after 6 h. The carrier, Cyanex 471X, selectively and efficiently transported Hg(II) ions in the presence of other associated metal ions. The method has been demonstrated to recover selectively mercury from waste samples and mercurochrome solution. © 2002 Society of Chemical Industry 相似文献
5.
Weiwei Wang Jianjun Liu Wenwei He Deqian Li 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(8):705-710
The kinetics of ytterbium(III) extraction from sulfate medium with Cyanex 923 in heptane has been investigated with a constant interfacial cell with laminar flow, which aimed to identify the extraction regime, reaction zone and rate equations. It was found that the extraction rate of ytterbium(III) increased linearly with stirring speed and specific interfacial area. The activation energy Ea (9.56 kJ mol?1), activation enthalpy ΔH± (7.05 kJ mol?1), activation entropy ΔS±298 (?0.31 kJ mol?1) and Gibbs free energy of activation ΔG±298 (98.3 kJ mol?1) were calculated from the dependence of extraction rate on temperature. The experiential rate equations were obtained by investigating the influence of the concentration of various species on the extraction rate. A diffusion regime has been deduced from evidence of the linear dependence of extraction rate on stirring speed and the low value of the activation energy. The liquid–liquid interface is most probably the reaction zone in view of the linear dependence of extraction rate on specific interfacial area, the high interfacial activity and low water‐solubility of extractant. Thus the mass transfer rate is controlled by interfacial film diffusion of species. Copyright © 2007 Society of Chemical Industry 相似文献
6.
Francisco Jos Alguacil Concepcin Caravaca María Isabel Martín 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(10):1048-1053
The transport of chromium(VI) through a flat‐sheet supported liquid membrane containing Cyanex 921 as a carrier has been investigated. The permeation of the metal is investigated as a function of various experimental variables: hydrodynamic conditions, concentration of chromium(VI) and HCl in the feed phase, carrier concentration and diluent in the membrane and strippant concentration in the stripping phase. The mass transfer coefficient and the thickness of the aqueous boundary layer were calculated from the experimental data. Furthermore, the selectivity of Cyanex 921‐based flat‐sheet supported liquid membrane towards different metal ions and the behaviour of the system against other carriers are presented. Copyright © 2003 Society of Chemical Industry 相似文献
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Devendra V Chavan Purushottam M Dhadke 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(8):925-932
Liquid–liquid extraction of Ir(III) and Rh(III) with Cyanex 923 from aqueous hydrochloric acid media has been studied. Quantitative extraction of Ir(III) was observed in the range of 5.0–8.0 mol dm?3 HCl with 0.1 mol dm?3 Cyanex 923, while Rh(III) was extracted quantitatively in the range of 1.0–2.0 mol dm?3 HCl with 0.05 mol dm?3 Cyanex 923 in toluene along with 0.2 mol dm?3 SnCl2. The Ir(III) was back extracted with 4.0 mol dm?3 HNO3 quantitatively from the organic phase while Rh(III) was stripped with 3.0 mol dm?3 HNO3. The extraction of Rh(III) with Cyanex 923 was not quantitative without use of SnCl2. However in the extraction of Ir(III) a negative trend was observed in the presence of SnCl2. Varying the temperature of extraction showed that the extraction reactions of both the metal ions are exothermic in nature, and the stoichiometric ratio of Ir(III)/Rh(III) to Cyanex 923 in organic phase was found to be 1:3. The methods developed were applied to the recovery of these metal ions from a synthetic solution of similar composition to that from leaching of spent autocatalysts in 6.0 mol dm?3 HCl. © 2002 Society of Chemical Industry 相似文献
10.
Junwen Lv 《Chemical engineering science》2007,62(21):6032-6039
Extraction capabilities of three kinds of carriers, Aliquat 336, Kelex 100 and LIX 54, for cadmium removal have been investigated in supported liquid membrane (SLM) systems. The maximum fluxes obtained using Aliquat 336, Kelex 100 and LIX 54 are 1.12×10-9, 1.5×10-10 and , respectively. Theoretical calculation of these three carriers’ extraction capabilities for cadmium in SLM systems using the quantum chemical computation method has also been carried out. The single point energy calculation results show that the energy changes in the complex formation process are in the order of Aliquat 336/Cd(II)>Kelex100/Cd(II)>LIX 54/Cd(II), with energy changes of -657.79, -329.19 and 96.32 kcal/mol, respectively. This indicates the quantum chemical computation supports the experimental results well and can be proposed as an effective tool for carrier selection in the SLM system. FTIR results also agree with the computational results quite well. Investigation on the influence of stirring rate and strippant on the cadmium flux reveals that a stirring rate of 400 rpm and the use of 1 mM EDTA as the strippant constitute the optimal experimental conditions. It was also found that cadmium flux is a function of feed concentration at the low concentration stage and the cadmium flux is enhanced by appropriate addition of certain anion into the feed. 相似文献
11.
Ting-Chia Huang Ruey-Shin Juang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1988,42(1):3-17
The rate and mechanism of copper, cobalt, nickel and zinc transport through a supported liquid membrane containing di(2-ethylhexyl) phosphoric acid as a mobile carrier were studied, respectively. The permeation rate equations have been derived taking into account aqueous film diffusion, interfacial chemical reaction and membrane diffusion as simultaneous controlling steps. The possible rate-controlling steps were estimated by comparing the relative values of the three successive resistances. The measured permeation rates of zinc agreed well with the proposed mechanism in this study. 相似文献
12.
Flora E Mercader‐Trejo Eduardo Rodríguez de San Miguel Josefina de Gyves 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(9):1323-1330
BACKGROUND: Regulatory controls to limit mercury emissions in waters have impacted on the development of membrane extraction‐based methodologies for its separation. The specific advantages (effective carrier immobilization, easy preparation, versatility, and good mechanical properties) of polymer inclusion membranes (PIMs) make them suitable for this purpose. In this work a novel procedure using PIMs for mercury separation with a commercial available extractant (Cyanex 471X) is described and evaluated through the determination of the efficiency parameters (permeability, selectivity, stability) and membrane characterization. RESULTS: Using a membrane composed of 30% cellulose triacetate (CTA), 60% 2‐nitrophenyl octyl ether (NPOE), and 10% w/w Cyanex 471X a 0.1 mmol dm?3 Hg(II) solution prepared in 0.01 mol dm?3 HCl was transported to a 0.05 mol dm?3 NaCl solution at pH 12.3 with permeability values in the feed and strip phases of 0.25 and 0.15 cm min?1, respectively. A diffusive Fickian‐type mechanism was inferred from the results. High separation factors ranging between 2 and 5900, less than 11% of competing metal ions transported, active transport of the metal ion and a successful reuse of the PIM were achieved. CONCLUSION: Optimized PIMs using Cyanex 471X represent an interesting alternative for Hg(II) removal from waters showing high efficiency factors and easy implementation. Copyright © 2009 Society of Chemical Industry 相似文献
13.
We have demonstrated, for the first time, P84 co-polyimide with novel chemical cross-linking modification can be effectively used as the polymeric microporous matrix for supported liquid membrane (SLM) applications. Both asymmetric and symmetric flat membranes with high tortuosity were fabricated via the phase inversion method. It is found that the symmetric membrane outperforms the asymmetric one because the former may provide (1) balanced forces exerted at two aqueous/membrane interfaces and (2) the formation of more stable stagnant layers than the latter. However, the performance of both unmodified asymmetric and symmetric flat membranes deteriorates severely after use for 20-30 h. A novel chemical modification agent, p-xylenediamine/water, was discovered and shows effectiveness to improve P84 membrane stability for SLM. The improved SLM stability is attributed to the reduced pore size and the enhanced hydrophobicity on the membrane surfaces. The newly developed chemically modified SLM has a similar lifetime compared with other SLM systems using commercial PTFE as the support matrix. 相似文献
14.
Francisco Jos Alguacil Ana María Sastre 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2000,75(7):577-582
The present work describes the mechanism of active transport of copper(II) through an immobilized liquid membrane (ILM) containing LIX 54 (β‐diketone) dissolved in Iberfluid as mobile carrier. An uphill transport model has been described and equations have been derived taking into account aqueous boundary layer diffusion and liquid membrane diffusion as simultaneous controlling factors. In the present model, various cases were discussed using the carrier LIX 54 and different chemical species; the diffusional membrane resistance for lower and higher concentrations of extractant was evaluated. The diffusion coefficients were observed to decrease with increase in the extractant concentration, ranging from 4.1 × 10−3 to 1.65 × 10−2 mol dm−3 Plotting [Cu]0−[Cu]t vs time resulted in a slope of [HR]0A/2ΔorgV taking into account the complex species, CuR2, in the membrane. The mass transfer coefficient (Δorg −1), the diffusion coefficient of the metal carrier species (Dorg) and the thickness of the aqueous boundary layer were calculated from the proposed model for LIX 54. More than 90% of the Cu(II) could be separated using LIX 54 in the presence of various metals such as Ni, Co(II) and Zn. © 2000 Society of Chemical Industry 相似文献
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ABSTRACT The transport of Ga(III) from chloride solution by supported liquid membrane (SLM) using organophosphorus acids as carriers was studied and compared with solvent extraction results. The diffusion coefficient, permeability coefficient and mass transfer resistance for both processes were analyzed by investigating various parameters, such as flow pattern, flow rate, pH, Ga(III)/extractant concentration and temperature. Under optimized conditions, the extraction percentage of 97.0% and permeability coefficient of 9.22 × 10?6 m/s was achieved for SLM process. Kinetic modeling was proposed to determine the mass diffusion coefficient of Ga(III) complex across the membrane and stability of this SLM system was also examined. 相似文献
16.
P Narayanan Remya M Lakshmipathy Reddy 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(7):734-741
The solvent extraction of magnesium(II), aluminium(III), titanium(IV), vanadium(V), chromium(III), manganese(II) and iron(III) from hydrochloric acid solutions has been investigated using the trialkylphosphine oxide Cyanex 923 (TRPO) in kerosene as extractant. The results demonstrate that titanium(IV), vanadium(V) and iron(III) are extracted into kerosene as TiOCl2·2TRPO, VO2Cl·TRPO and HFeCl4·2TRPO, respectively. On the other hand magnesium(II), aluminium(III), chromium(III) and manganese(II) are not extracted with TRPO from hydrochloric acid solutions (1.0–4.0 mol dm?3) under the experimental conditions. IR spectral studies of the extracted complexes were further used to clarify the nature of the extracted complexes. The effect of the diluent on the extraction of titanium(IV), vanadium(V) and iron(III) has been studied and correlated with the dielectric constant. The loading capacity of the TRPO system has been evaluated and the potential for the separation and recovery of titanium(IV), vanadium(V) and iron(III) from simulated waste chloride liquors of the titanium minerals processing industry has been assessed. Copyright © 2004 Society of Chemical Industry 相似文献
17.
In order to compare the separation of Ir(IV) and Rh(III) between SnCl2 and ascorbic acid as a reducing agent, solvent extraction with Cyanex 921 and Cyanex 301 was investigated in the HCl concentration range from 1 M to 9 M. Addition of both SnCl2 and ascorbic acid led to the selective extraction of rhodium by the two extractants, leaving Ir(III) in the raffinate. Since tin was selectively extracted over Rh(I) in the presence of SnCl2, it is necessary to separate Rh(I) and tin by selective stripping from the organic phase. In the presence of ascorbic acid, the extraction percentage of rhodium by Cyanex 921 was much smaller than that in the presence of SnCl2. UV spectra was analyzed to verify the reduction reaction of both metal ions. FT-IR was analyzed between fresh and loaded organic solution. The reduction of Ir(IV) and Rh(III) in the presence of ascorbic acid was explained. Selective stripping of Rh(I) over tin from the loaded Cyanex 921 was obtained by the mixture of HCl and (NH2)2CS. 相似文献
18.
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. 相似文献
19.
Facilitated transport of Cs-137 across supported liquid membranes (SLM) containing a calix-crown ligand viz. caliz[4]arene-bis(crown-6) (CC), calix[4]arene-bis(o-benzocrown-6) (CBC) or calix[4]arene-bis(napthocrown-6) (CNC) was investigated. The feed consisted of dilute nitric acid solutions while the carrier solutions contained mainly CNC in several organic diluents inside the pores of polypropylene (PP) as well as PTFE flat sheet membranes. PTFE membranes containing CNC in a diluent mixture of 2-nitrophenyloctyl ether (NPOE) and n-dodecane were found to have high stability. Selectivity studies were carried out using simulated high level waste (SHLW) as well as fission products obtained from an irradiated natural uranium target. 相似文献
20.
Bipan Bansal Xiao Dong Chen Md. Monwar Hossain 《Chemical Engineering and Processing: Process Intensification》2005,44(12):1327-1336
A mathematical transport model is developed for the extraction of lithium from dilute synthetic solution, simulating geothermal water, using a supported liquid membrane (SLM) of LIX54 (major component is -acetyl-m-dodecylacetophenone) and TOPO (tri-n-octylphosphine oxide) in kerosene. The model is based on fundamental mass transfer and kinetics mechanisms that account for all possible transport resistances. The model is solved numerically and is used to investigate the effect of various extraction conditions and membrane support characteristics. Reasonable agreement is found between the predicted and the experimental results reported in literature. 相似文献