DD Ensor - Academia.edu (original) (raw)
Papers by DD Ensor
Analytical Chemistry, 1986
Didodecylnaphthalenesulfonic acid, HDDNS, has been shown to be a useful liquid-liquid cation exch... more Didodecylnaphthalenesulfonic acid, HDDNS, has been shown to be a useful liquid-liquid cation exchanger for lanthanide elements. Its strong acid character makes the compound an effective extractant even at low pH, but it shows little ability to separate individual trivalent lanthanide ions from each other. In an effort to introduce more selectivity into the extraction of lanthanide ions by HDDNS, a
Journal of Radioanalytical and Nuclear Chemistry, 2017
The separation of americium(III) from europium(III) was achieved utilizing a bis-2,6-(5,6,7,8-tet... more The separation of americium(III) from europium(III) was achieved utilizing a bis-2,6-(5,6,7,8-tetrahydro-5,9,9-trimethyl-5,8-methano-1,2,4-benzotriazin-3-yl) pyridine (CA-BTP) chromatographic resin. The extraction chromatographic materials were prepared using various concentrations of CA-BTP. This new, hydrolytically stable extractant was impregnated on an inert polymeric support at 40% loading. The uptake of Am(III) and Eu(III) by this material from 0.1 to 4.0 M aqueous HNO 3 solutions was measured. The resulting dry weight distribution ratios, D w , indicated a strong preference for Am(III) with little affinity for Eu(III). These results are similar to recently reported solvent extraction studies indicating a maximum uptake of Am(III) in the 0.5-1.0 M HNO 3 range. The resin preparation, performance, and characterization of the Am/Eu separation are reported herein.
Separation Science and Technology, 2016
ABSTRACT Cesium stripping performance of thermally stressed solvent worsens slowly over time in b... more ABSTRACT Cesium stripping performance of thermally stressed solvent worsens slowly over time in batch tests of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process. NG-CSSX is currently used in full-scale equipment at the Savannah River Site for the selective removal of caesium from high-level salt waste. Recently, a new guanidine, N,N’,N”-tris(3,7-dimethyloctyl)guanidine (TiDG), was chosen for use as the suppressor, a lipophilic organic base needed for stripping, and the present study was undertaken to address the question of its stability. The NG-CSSX process solvent was evaluated for a period of three months under a variety of temperature and storage conditions. The performance of the solvent was tested at 30-day increments using an extraction, scrub, strip and extraction (ES2S3E) sequence. The results provide insights into the effects of storage and process conditions, the stripping behaviour of TiDG and the stability of the new solvent composition.
4.1. Synthetic procedure for 1,3-Dicyclohexyl-2-(isotridecyl)guanidine hydrochloride. ...... 4.2.... more 4.1. Synthetic procedure for 1,3-Dicyclohexyl-2-(isotridecyl)guanidine hydrochloride. ...... 4.2. GC chromatogram of crude DCiTG with retention time and compound assignments .... 4.3. The free base has a decomposition onset at ºC while the hydroxide is at 275 ºC and hydrochloride is at 282 ºC.
Solvent Extraction and Ion Exchange, 2015
ABSTRACT Among the different components present in spent nuclear fuel, long-lived trivalent actin... more ABSTRACT Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. Selective extraction of americium from acidic solution (up to 2M HNO3) containing tenth molar quantities of lanthanides has been achieved using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented.
The effective simultaneous extraction of cesium and strontium from high level nuclear waste has r... more The effective simultaneous extraction of cesium and strontium from high level nuclear waste has received renewed interest as a result of the proposed recycling of civilian nuclear fuel. Removal of the radionuclides of cesium and strontium, which initially account for the majority of radioactivity and heat production, from the waste would drastically reduce the amount of waste requiring long-term geologic storage, as well as reduce costs of building a recycling facility. The extraction characteristics of 137Cs and 85Sr were studied using a variety of modifiers in the solvent. The effects of various solvent modifiers were measured as a function of concentrations of extractants, aqueous acidity, and third phase formation. Experimental results indicate that a viable simultaneous extraction system for cesium and strontium from highly acidic waste can be developed.
Journal of Inorganic and Nuclear Chemistry, 1980
ABSTRACT The thermodynamic parameters of complexation of Ce(III), Eu(III), Tm(III) and Am(III) by... more ABSTRACT The thermodynamic parameters of complexation of Ce(III), Eu(III), Tm(III) and Am(III) by ClCH2CO2−, Cl2CHCO2− and Cl3CCO2− have been measured by potentiometry, solvent extraction and calorimetry in a medium of 2.0 M (NaClO4). The log of the stability constants of any particular cation correlated linearly with the ligand pKa. From comparison of the entropy data it is proposed that the ratio of inner to outer sphere nature of the complexes varies in the order LnClAc2+ > LnCl2Ac2+ > LnCl3Ac2+.
Journal of Inorganic and Nuclear Chemistry, 1977
Separations of f Elements, 1995
The stoichiometry and stability constants for americium and europium complexes with phosphonoacet... more The stoichiometry and stability constants for americium and europium complexes with phosphonoacetic acid (H02CCH2P03H2-PAA) in dilute acid solutions (0.005 to 0.02 M) have been determined by distribution methods at 0.5 M ionic strength and 25.0°C. The identified Am and Eu complexes and log P,,l/ll values are A~I (H~L)~+-13.82(*0.04), Am(HL)+-11.62(*0.04), Am(H2L)2+-27.35(f0.01), Eu(HL)+-12.10(f0.05), Eu(H?L)2+-27.8 l(*U.Ol), Eu(HL)2'-23.08(*0.05). The Eu complexes are stronger than Am complexes of comparable stoichiometry, in accord with the electrostatic nature of the metal-ligand interaction. PAA was tested as a potential agent of enhanced Ani/Eu separation in solvent extraction systems by examining Am and Eu extraction using different extractants. For extraction into bis(2-ethyIhexy1)phosphoric acid (HDEHP), PAA slightly reduces the Am/Eu separation factor. With dinonylnapthalenesulfonic acid (HDNNS), or octyl(pheny1)-N,N-diisobutyl-carbamoylmethylphosphme oxide (CMP0)-nitrate extraction systems, SsuAm is slightly enhanced by PAA. A three fold increase in SE"~''' is nbserved in CMPO extraction from 0.5 M KSCNFAA media (over extraction from 0.5 M KSCN) suggesting an improved method for lanthanide/trivalent actinide separation. Work performed under the auspices of the Office of Basic Energy Sciences, Division of Chemical Sciences, U. S. Department of Energy, under contract W-3 1-109-ENG-38 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.
The Journal of Physical Chemistry, 1974
The heats of mixing of tetrapropylammonium chloride with LiC1, KCl, and NaCl at 0.5 m have been m... more The heats of mixing of tetrapropylammonium chloride with LiC1, KCl, and NaCl at 0.5 m have been measured over a 40-80" temperature range. The heats of dilution of tetrapropylammonium chloride have been measured at 40 and 80" over the concentration range of 0.1 to 2.0 m. The heats of mixing show relatively little temperature dependence except near 80". The heat of dilution decreased with increasing temperature above 0.7 m. The results have been interpreted in terms of the temperature effect on hydrophobic interactions of the tetrapropylammonium cation.
The guanidine recommended for the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) proce... more The guanidine recommended for the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process is N,N',N"-tris(3,7-dimethyloctyl)guanidine (TiDG). Systematic testing has shown that it is significantly more lipophilic than the guanidine employed previously, N,N'-dicyclohexyl-N"isotridecylguanidine (DCiTG), which is the active extractant in the commercial guanidine product LIX ®-79, while not otherwise changing the solvent performance. Previous testing indicated that the extent of partitioning of the DCiTG suppressor to the aqueous strip solution is significantly greater than expected, potentially leading to rapid depletion of the suppressor from the solvent and unwanted organic concentrations in process effluents. Five candidate guanidines were tested as potential replacements for DCiTG. The tests included batch extraction with simulated waste and flowsheet solutions, third-phase formation, emulsion formation, interfacial tension, dispersion number (coalescence rate), and partition ratios of the guanidine between the solvent and aqueous strip solution. Preliminary results of a thermal stability test of the TiDG solvent at one-month duration indicated performance approximately equivalent to DCiTG. Two of the guanidines proved adequate in all respects, and TiDG was deemed slightly preferable vs. the next best performing guanidine BiTABG.
Solvent Extraction and Ion Exchange, 2007
Page 1. Extraction of Cesium by a Calix[4]arene-Crown-6 Ether Bearing a Pendant Amine Group Ben W... more Page 1. Extraction of Cesium by a Calix[4]arene-Crown-6 Ether Bearing a Pendant Amine Group Ben W. Harmon and Dale D. Ensor Department of Chemistry, Tennessee Technological University Cookeville, TN, USA Lætitia ...
Solvent Extraction and Ion Exchange, 2013
Studies have shown a much enhanced differentiation between trivalent actinides and trivalent lant... more Studies have shown a much enhanced differentiation between trivalent actinides and trivalent lanthanides when substituted alkyl dithiophosphinic acids are utilized as the active phase transfer reagents. We present a study evaluating the use of a synergistic combination of bis(o-trifluoromethylphenyl)dithiophosphinic acid and trioctylphosphine oxide for the complete actinide recovery from UREX-like raffinates. A complete single-step separation of uranium, neptunium, plutonium, and americium from aqueous mixtures containing 0.5 M nitric acid and a total fission product content of 5.5 g/L (45 mM) has been demonstrated.
Journal of Chemical & Engineering Data, 1973
Journal of Chemical & Engineering Data, 1975
The heats of dilution of KCI, MgCI2, Na2S04, and MgS04 were measured over a concentration range o... more The heats of dilution of KCI, MgCI2, Na2S04, and MgS04 were measured over a concentration range of 0.005-2.0m at temperatures between 4O-8O0C. The data were extrapolated to infinite dilution by use of the Debye-Huckel limiting law to obtain relative apparent molal heat ...
Journal of Inorganic and …, 1981
... tS1; EC HT F JRP 0 180 [ ..tJ 'ri ,1,[ J i ,.,1 ' lI , , , 28 qO 60 80 100 120 ,,, ... more ... tS1; EC HT F JRP 0 180 [ ..tJ 'ri ,1,[ J i ,.,1 ' lI , , , 28 qO 60 80 100 120 ,,, ,,I. ,j I ' i lqO I60 BKF3 THI3R 'IX '4BIC P,=6.7QB=?,O9 C=q.ql [N=9 OENI'Tr9.7061[[ LT FOFIf4 JIP 0 20 qo I ... 4. RD Baybarz, JB Knauer and PB Orr, Oak Ridge National Laboratory Document ORNL4672 (1973 ...
Chemischer Informationsdienst
Chemischer Informationsdienst
Chemischer Informationsdienst
Analytical Chemistry, 1986
Didodecylnaphthalenesulfonic acid, HDDNS, has been shown to be a useful liquid-liquid cation exch... more Didodecylnaphthalenesulfonic acid, HDDNS, has been shown to be a useful liquid-liquid cation exchanger for lanthanide elements. Its strong acid character makes the compound an effective extractant even at low pH, but it shows little ability to separate individual trivalent lanthanide ions from each other. In an effort to introduce more selectivity into the extraction of lanthanide ions by HDDNS, a
Journal of Radioanalytical and Nuclear Chemistry, 2017
The separation of americium(III) from europium(III) was achieved utilizing a bis-2,6-(5,6,7,8-tet... more The separation of americium(III) from europium(III) was achieved utilizing a bis-2,6-(5,6,7,8-tetrahydro-5,9,9-trimethyl-5,8-methano-1,2,4-benzotriazin-3-yl) pyridine (CA-BTP) chromatographic resin. The extraction chromatographic materials were prepared using various concentrations of CA-BTP. This new, hydrolytically stable extractant was impregnated on an inert polymeric support at 40% loading. The uptake of Am(III) and Eu(III) by this material from 0.1 to 4.0 M aqueous HNO 3 solutions was measured. The resulting dry weight distribution ratios, D w , indicated a strong preference for Am(III) with little affinity for Eu(III). These results are similar to recently reported solvent extraction studies indicating a maximum uptake of Am(III) in the 0.5-1.0 M HNO 3 range. The resin preparation, performance, and characterization of the Am/Eu separation are reported herein.
Separation Science and Technology, 2016
ABSTRACT Cesium stripping performance of thermally stressed solvent worsens slowly over time in b... more ABSTRACT Cesium stripping performance of thermally stressed solvent worsens slowly over time in batch tests of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process. NG-CSSX is currently used in full-scale equipment at the Savannah River Site for the selective removal of caesium from high-level salt waste. Recently, a new guanidine, N,N’,N”-tris(3,7-dimethyloctyl)guanidine (TiDG), was chosen for use as the suppressor, a lipophilic organic base needed for stripping, and the present study was undertaken to address the question of its stability. The NG-CSSX process solvent was evaluated for a period of three months under a variety of temperature and storage conditions. The performance of the solvent was tested at 30-day increments using an extraction, scrub, strip and extraction (ES2S3E) sequence. The results provide insights into the effects of storage and process conditions, the stripping behaviour of TiDG and the stability of the new solvent composition.
4.1. Synthetic procedure for 1,3-Dicyclohexyl-2-(isotridecyl)guanidine hydrochloride. ...... 4.2.... more 4.1. Synthetic procedure for 1,3-Dicyclohexyl-2-(isotridecyl)guanidine hydrochloride. ...... 4.2. GC chromatogram of crude DCiTG with retention time and compound assignments .... 4.3. The free base has a decomposition onset at ºC while the hydroxide is at 275 ºC and hydrochloride is at 282 ºC.
Solvent Extraction and Ion Exchange, 2015
ABSTRACT Among the different components present in spent nuclear fuel, long-lived trivalent actin... more ABSTRACT Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. Selective extraction of americium from acidic solution (up to 2M HNO3) containing tenth molar quantities of lanthanides has been achieved using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented.
The effective simultaneous extraction of cesium and strontium from high level nuclear waste has r... more The effective simultaneous extraction of cesium and strontium from high level nuclear waste has received renewed interest as a result of the proposed recycling of civilian nuclear fuel. Removal of the radionuclides of cesium and strontium, which initially account for the majority of radioactivity and heat production, from the waste would drastically reduce the amount of waste requiring long-term geologic storage, as well as reduce costs of building a recycling facility. The extraction characteristics of 137Cs and 85Sr were studied using a variety of modifiers in the solvent. The effects of various solvent modifiers were measured as a function of concentrations of extractants, aqueous acidity, and third phase formation. Experimental results indicate that a viable simultaneous extraction system for cesium and strontium from highly acidic waste can be developed.
Journal of Inorganic and Nuclear Chemistry, 1980
ABSTRACT The thermodynamic parameters of complexation of Ce(III), Eu(III), Tm(III) and Am(III) by... more ABSTRACT The thermodynamic parameters of complexation of Ce(III), Eu(III), Tm(III) and Am(III) by ClCH2CO2−, Cl2CHCO2− and Cl3CCO2− have been measured by potentiometry, solvent extraction and calorimetry in a medium of 2.0 M (NaClO4). The log of the stability constants of any particular cation correlated linearly with the ligand pKa. From comparison of the entropy data it is proposed that the ratio of inner to outer sphere nature of the complexes varies in the order LnClAc2+ > LnCl2Ac2+ > LnCl3Ac2+.
Journal of Inorganic and Nuclear Chemistry, 1977
Separations of f Elements, 1995
The stoichiometry and stability constants for americium and europium complexes with phosphonoacet... more The stoichiometry and stability constants for americium and europium complexes with phosphonoacetic acid (H02CCH2P03H2-PAA) in dilute acid solutions (0.005 to 0.02 M) have been determined by distribution methods at 0.5 M ionic strength and 25.0°C. The identified Am and Eu complexes and log P,,l/ll values are A~I (H~L)~+-13.82(*0.04), Am(HL)+-11.62(*0.04), Am(H2L)2+-27.35(f0.01), Eu(HL)+-12.10(f0.05), Eu(H?L)2+-27.8 l(*U.Ol), Eu(HL)2'-23.08(*0.05). The Eu complexes are stronger than Am complexes of comparable stoichiometry, in accord with the electrostatic nature of the metal-ligand interaction. PAA was tested as a potential agent of enhanced Ani/Eu separation in solvent extraction systems by examining Am and Eu extraction using different extractants. For extraction into bis(2-ethyIhexy1)phosphoric acid (HDEHP), PAA slightly reduces the Am/Eu separation factor. With dinonylnapthalenesulfonic acid (HDNNS), or octyl(pheny1)-N,N-diisobutyl-carbamoylmethylphosphme oxide (CMP0)-nitrate extraction systems, SsuAm is slightly enhanced by PAA. A three fold increase in SE"~''' is nbserved in CMPO extraction from 0.5 M KSCNFAA media (over extraction from 0.5 M KSCN) suggesting an improved method for lanthanide/trivalent actinide separation. Work performed under the auspices of the Office of Basic Energy Sciences, Division of Chemical Sciences, U. S. Department of Energy, under contract W-3 1-109-ENG-38 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.
The Journal of Physical Chemistry, 1974
The heats of mixing of tetrapropylammonium chloride with LiC1, KCl, and NaCl at 0.5 m have been m... more The heats of mixing of tetrapropylammonium chloride with LiC1, KCl, and NaCl at 0.5 m have been measured over a 40-80" temperature range. The heats of dilution of tetrapropylammonium chloride have been measured at 40 and 80" over the concentration range of 0.1 to 2.0 m. The heats of mixing show relatively little temperature dependence except near 80". The heat of dilution decreased with increasing temperature above 0.7 m. The results have been interpreted in terms of the temperature effect on hydrophobic interactions of the tetrapropylammonium cation.
The guanidine recommended for the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) proce... more The guanidine recommended for the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process is N,N',N"-tris(3,7-dimethyloctyl)guanidine (TiDG). Systematic testing has shown that it is significantly more lipophilic than the guanidine employed previously, N,N'-dicyclohexyl-N"isotridecylguanidine (DCiTG), which is the active extractant in the commercial guanidine product LIX ®-79, while not otherwise changing the solvent performance. Previous testing indicated that the extent of partitioning of the DCiTG suppressor to the aqueous strip solution is significantly greater than expected, potentially leading to rapid depletion of the suppressor from the solvent and unwanted organic concentrations in process effluents. Five candidate guanidines were tested as potential replacements for DCiTG. The tests included batch extraction with simulated waste and flowsheet solutions, third-phase formation, emulsion formation, interfacial tension, dispersion number (coalescence rate), and partition ratios of the guanidine between the solvent and aqueous strip solution. Preliminary results of a thermal stability test of the TiDG solvent at one-month duration indicated performance approximately equivalent to DCiTG. Two of the guanidines proved adequate in all respects, and TiDG was deemed slightly preferable vs. the next best performing guanidine BiTABG.
Solvent Extraction and Ion Exchange, 2007
Page 1. Extraction of Cesium by a Calix[4]arene-Crown-6 Ether Bearing a Pendant Amine Group Ben W... more Page 1. Extraction of Cesium by a Calix[4]arene-Crown-6 Ether Bearing a Pendant Amine Group Ben W. Harmon and Dale D. Ensor Department of Chemistry, Tennessee Technological University Cookeville, TN, USA Lætitia ...
Solvent Extraction and Ion Exchange, 2013
Studies have shown a much enhanced differentiation between trivalent actinides and trivalent lant... more Studies have shown a much enhanced differentiation between trivalent actinides and trivalent lanthanides when substituted alkyl dithiophosphinic acids are utilized as the active phase transfer reagents. We present a study evaluating the use of a synergistic combination of bis(o-trifluoromethylphenyl)dithiophosphinic acid and trioctylphosphine oxide for the complete actinide recovery from UREX-like raffinates. A complete single-step separation of uranium, neptunium, plutonium, and americium from aqueous mixtures containing 0.5 M nitric acid and a total fission product content of 5.5 g/L (45 mM) has been demonstrated.
Journal of Chemical & Engineering Data, 1973
Journal of Chemical & Engineering Data, 1975
The heats of dilution of KCI, MgCI2, Na2S04, and MgS04 were measured over a concentration range o... more The heats of dilution of KCI, MgCI2, Na2S04, and MgS04 were measured over a concentration range of 0.005-2.0m at temperatures between 4O-8O0C. The data were extrapolated to infinite dilution by use of the Debye-Huckel limiting law to obtain relative apparent molal heat ...
Journal of Inorganic and …, 1981
... tS1; EC HT F JRP 0 180 [ ..tJ 'ri ,1,[ J i ,.,1 ' lI , , , 28 qO 60 80 100 120 ,,, ... more ... tS1; EC HT F JRP 0 180 [ ..tJ 'ri ,1,[ J i ,.,1 ' lI , , , 28 qO 60 80 100 120 ,,, ,,I. ,j I ' i lqO I60 BKF3 THI3R 'IX '4BIC P,=6.7QB=?,O9 C=q.ql [N=9 OENI'Tr9.7061[[ LT FOFIf4 JIP 0 20 qo I ... 4. RD Baybarz, JB Knauer and PB Orr, Oak Ridge National Laboratory Document ORNL4672 (1973 ...
Chemischer Informationsdienst
Chemischer Informationsdienst
Chemischer Informationsdienst