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Summary When incorporated into a polymer hydrogel, the metal chelator, N,N,N,N-tetrakis(2-hydroxypropyl)ethylenediamine (THPED), retains its metal binding properties. The resultant poly(THPED methacrylate) homopolymer is a polybase with displacement binding constants for copper (II) and zinc(II) of-3.11 and-6.55, respectively, as compared to values for THPED of-3.83 and-7.44. The chelating capacity of the polymer for various divalent metal ions at pH 5.5 follows the order Cu>Cd>Co>Zn>Mn, while calcium and magnesium do not bind. Metal ion release curves indicate that after 30 hours, Cd(II), Co(II), Zn(II), and Mn(II) are released at a slow, steady rate, while Cu(II) is not released under experimental conditions. 相似文献
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《分离科学与技术》2012,47(6):965-971
The extraction properties of N,N,N′,N′-tetra(2-ethylhexyl)thiodiglycolamide T(2EH)TDGA have been evaluated for the separation and recovery of palladium from simulated high-level liquid waste (SHLW). T(2EH)TDGA has shown very high selectivity for Pd (II) over other metal ions present in SHLW. The separation factor (SF) for Pd (II) over other metal ions was found to be more than 105. Reusability studies of the extractant indicate that DPd remained almost constant even after five successive cycles of extraction and stripping. Palladium was quantitatively recovered from thiourea strip solution by treating it with ammonia and filtering the precipitate of palladium sulphide. The acid uptake constant (KH) was found to be 0.62 which could be due to the presence of two carbonyl groups of amidic moiety. To account for very high extractability of palladium with T(2EH)TDGA over other ‘S’ donor extractants, namely Bis-(2-ethylhexyl)sulphoxide (BESO), FTIR, as well as Raman studies were carried out. FTIR and Raman studies suggested the ligation through carbonyl as well as the thio-ether group. Conditional extraction constants (log K′ex) were determined and the thermodynamic parameters were calculated from the dependence of the conditional extraction constant (log K′ex) on temperature. The calculated values of ΔGex, ΔHex, and ΔSex were ?41.78 kJmol?1, ?55.12 kJmol?1 and ?44.04 JK?1 mol?1 respectively. The extraction process is indicated to be enthalpy driven with the entropy factor counteracting it. 相似文献
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The extraction behavior of rare earth (RE) elements from thiocyanate medium by N,N,N’,N’-tetra(2-ethylhexyl) diglycolamide (TEHDGA), a neutral extractant, has been investigated and the optimum conditions for their separations were determined. Isodecyl alcohol was used as phase modifier and a concentration of 5%(v/v) was found sufficient to mitigate third phase formation under our experimental conditions. The extraction mechanism of RE with TEHDGA was established by analyzing distribution data with slope analysis technique and showed the formation of a neutral species, RE(SCN)3.2TEHDGA, in the organic phase. The extraction of rare earth decreased with increase in temperature indicating exothermic nature and the enthalpy change (ΔH) obtained for Y(III) was ?14.27 kJ/mol. Among various stripping agents studied, oxalic acid was found to be efficient in quantitative stripping of rare earths from TEHDGA. The extraction efficiency for all the rare earths by TEHDGA was also investigated. High separation factor of 6.4 for Er/Y pair at 0.03 M thiocyanate has indicated the feasibility of using TEHDGA as extractant to separate Y from heavy rare earths, in particular Er, from thiocyanate medium. 相似文献
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《分离科学与技术》2012,47(10):1541-1554
Hollow fiber contactor was used to study non-dispersive extraction (NDSX) of Nd3+ ions from aqueous solutions. N,N,N′,N′-tetraoctyl diglycolamide (TODGA) diluted with n-dodecane was used as the organic phase with di-n-hexyl octanamide (DHOA) as the phase modifier. The role of cations (H+/Na+) on the transport of Nd3+ ions has been investigated for this system. It was observed that H+ ion has a significant role to play in the Nd3+/TODGA complexation reaction. A mathematical model has also been developed to simulate the NDSX process in a hollow fiber contactor. A comparison has also been made between extraction profiles from the NDSX process and the hollow fiber supported liquid membrane (HFSLM) process. It was observed that NDSX gave comparatively faster rates of extraction in the presence of H+ ions but slower in the absence of H+ ions. 相似文献
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张澍声 《精细与专用化学品》1988,(10)
分了C:7H。。一e一NH一CH:CH:一NH一C一Ci:Ha。 C:.H,eN,O: 分子量593 l英文名IN,N‘一Ethylene bis(s-tearanl记e) l国外商品名1 Chemetronwa、一100(Chemetron);Armowax EBS(Armak)书H佣ehst WaxC(Hoechst);AerawaxC(Glyeo),Kemam溉w 20(枷mko);Lubro/EA(ICI)。 l性状】白色至淡黄色粉末或粒状物。熔点130一145℃,闪点约285℃,比重0.98。不溶于水,常温下不溶于乙醇、丙酮等大多数溶剂,可溶于混合二甲苯、菇烯、丁醇、甲基溶纤素及大多数氯代烃类。游离脂肪酸含量低于4%,水份低于。.5%。 【制法】乙撑双硬脂酞胺的制备是… 相似文献
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Kathryn M. L. Taylor-Pashow Fernando F. Fondeur Thomas L. White David P. DiPrete 《分离科学与技术》2015,50(18):2866-2872
Several analytical methods were evaluated for determining the concentration of N,N’,N”-tris(3,7-dimethyloctyl)guanidine (TiDG) in a cesium extraction solvent. Of the methods evaluated, non-aqueous titration and 1H NMR were shown to be successful at quantifying the amount of TiDG present in both a pure solvent extraction system, and a blended system containing an additional base, trioctylamine. 相似文献
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《分离科学与技术》2012,47(10):1521-1526
Synthesis and characterization of N,N,N′,N′-tetraoctylglutaricamide (TOGA) was carried out and used for extraction of U(VI) and Th(IV) from nitric acid solutions. The processes of extraction were determined by the slope analysis and by analyzing a function that allows the simultaneous treatment of all the experimental points obtained in different conditions. The different factors affecting the extraction distribution ratio(D) of U(VI) and Th(IV) (extraction concentration, concentrations of nitric acid, salting-out agent NaNO3 concentration, equilibration time, temperature, and types of diluents) were investigated. The results obtained indicated that the extraction species of U(VI) and Th(IV) are mainly extracted as UO2(NO3)2·1.0TOGA and Th(NO3)4·1.5TOGA. The apparent equilibrium constant of U(VI) and Th(IV) extraction determined are 3.35 ± 0.03 L3/mol3 and 1.87 ± 0.01 L5/mol5 at 298 ± 1 K. Thermodynamic parameters such as the free energy(ΔG), enthalpy(ΔH), and entropy(ΔS) changes associated with the extraction processes could be evaluated. Back-extraction of U(VI) and Th(IV) from organic phases was also studied. 相似文献
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Larissa Klaß Andreas Wilden Fabian Kreft Christoph Wagner Andreas Geist Petra J. Panak 《溶剂提取与离子交换》2013,31(5):297-312
ABSTRACTN,N,N’,N’-tetraethyldiglycolamide (TEDGA) is used in the French EXAm (extraction of americium) process to separate Am(III) from Cm(III) and Ln(III). In this study, the complexation behavior of TEDGA towards actinides(III) and lanthanides(III) was compared to its methyl-substituted derivatives Me-TEDGA and Me2-TEDGA under experimental conditions applying to the EXAm process. Using the EXAm solvent, 0.6 mol/L N,N’-dimethyl-N,N’-dioctyl-hexylethoxymalonamide (DMDOHEMA) and 0.45 mol/L bis(2-ethylhexyl)-phosphoric acid (HDEHP), An(III) and Ln(III) distribution ratios increase in the order TEDGA < Me-TEDGA < Me2-TEDGA. This is explained by differences in the strength of complexation in the aqueous phase: Conditional stability constants for the formation of [Cm(DGA)x]3+ complexes decrease in the order TEDGA > Me-TEDGA > Me2-TEDGA, as shown by time-resolved laser fluorescence spectroscopy (TRLFS). TRLFS measurements verified the exclusive existence of [Cm(DGA)3]3+ complexes in the aqueous phase. Both the homoleptic [Cm(DMDOHEMA)n]3+ and the heteroleptic [Cm(DGA)x(DMDOHEMA)y]3+ complexes were detected in the organic phase, as postulated in the literature.[14] 相似文献
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Cationic polymerization of N,N,N-trimethyl–N-2-methacryl oxyethyl ammonium chloride (DMAEM-MC) was studied using a new synthesis technique and new initiator system, Sn2+. The Sn2+ was produced by the electrolysis of a sacrificial anode. The polymer was prepared in a batch reactor using only Sn material as electrodes. Factors affecting the conversion and average molecular weight of the polymer by electrolysis were obtained. On the one hand, the results indicated that the agitation rate, initial pH, current density and assembly of electrodes significantly affected both conversion and polymer molecular weight. On the other hand, temperature and monomer concentration were minor factors in the electropolymerization, while these two factors were the major factors in conventional chemical methods. The optimal pHi and agitation rate were 5.50 and 0 rpm, respectively. The reaction rate increased with current density; however, the current efficiency decreased with increase in current density. The results also revealed that the optimum reaction temperature and monomer concentration were 25 C and 0.73 m, respectively. 相似文献
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Abstract Diglycolamides have emerged as an interesting class of extractants for actinide partitioning from high-level waste (HLW). N,N,N´,N´-tetraoctyl diglycolamide (TODGA) has been extensively studied for lanthanide-actinide co-extraction behavior. The present work deals with a branched isomer of TODGA, that is, N,N,N´,N´-tetra(2-ethylhexyl) diglycolamide (TEHDGA). TEHDGA was studied for the extraction of 241Am and third-phase formation. The effect of using different phase modifiers on the prevention of the formation of a third phase during nitric acid extraction by TEHDGA along with the acid uptake behavior by TEHDGA in the presence of the modifiers was studied. The modifiers used for this purpose were di(n-hexyl)octanamide (DHOA), isodecanol, and n-decanol. The effect of the modifiers on the uptake of 241Am as a function of acid concentration and as a function of modifier concentration was also examined. DHOA was found to be a suitable modifier, in spite of its high acid uptake. The uptake of lanthanides Ce, La, Eu, Gd, and Nd and elements such as Fe, Ni, Mn, Mo, Ru, Sr, and Cs with DHOA-modified TEHDGA–n-dodecane solvent systems were investigated. The results obtained indicated that, while DHOA-modified TEHDGA/n-dodecane extracted lanthanides and actinides, it did not show any significant uptake of other elements. Thus, the TEHDGA-DHOA/n-dodecane solvent system can be used effectively for the partitioning of lanthanides and actinides from HLW. 相似文献
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《分离科学与技术》2012,47(7):1049-1055
The extraction properties of N,N,N',N'-tetra-(2-ethylhexyl) dithiodiglycolamide (DTDGA) have been evaluated for separation and recovery of palladium from simulated high-level liquid waste (SHLW) solution. Extraction of Pd was found to increase with increase in nitric acid concentration up to 4.0 M, above which the extraction remains almost constant. Acid uptake studies show 1:1 stoichiometry between DTDGA and HNO3 at nitric acid concentration above 3.0 M. The acid uptake constant (KH) was found to be 0.60 which could be due to the presence of two carbonyl groups of amidic moiety. DTDGA has shown very high extractability and selectivity for Pd over other metal ions present in SHLW. The separation factor (SF) for Pd over other metal ions was found to be more than 104. Almost complete back extraction of palladium from organic phase was achieved with 0.01 M thiourea in 0.1 M nitric acid. Reusability studies of the extractant indicate that DPd remains almost constant even after five successive cycles of extraction and stripping. Two extraction stages will be required for complete extraction of 100 mg/L Palladium in 3.0 M nitric acid solution using 0.0025 M DTDGA/n-dodecane solvent system. 相似文献
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