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Capillary electrokinetic separations: Influence of mobile phase composition on performance

Description: The composition of the mobile phase employed in capillary zone electrophoresis and the related technique, micellar electrokinetic capillary chromatography, is an important factor in determining separation performance. The influences of ionic salt, surfactant, and organic solvent mobile phase additives on separation efficiency, retention, and elution range are discussed and demonstrated. 23 refs., 2 figs., 2 tabs.
Date: January 1, 1990
Creator: Sepaniak, M.J.; Swaile, D.F.; Powell, A.C. & Cole, R.O.
Partner: UNT Libraries Government Documents Department

Carrier facilitated transport through membranes

Description: Facilitated transport is a process whereby the diffusion of a solute across a membrane is chemically enhanced. In this report an analysis is given of a facilitated transport system involving a volatile species A which reacts with a nonvolatile carrier species B to form the nonvolatile product AB. The species A is transported across the membrane by ordinary diffusion, as well as by the diffusion of the product AB. It is assumed that the reaction rates are large, so the reactions are confined mostly to thin boundary layers near the surfaces of the membrane. The method of matched asymptotic expansions is used to derive the asymptotic solution of the nonlinear boundary value problem governing equilibrium. The effect of various parameters on the facilitation factor is analyzed in detail.
Date: June 1, 1980
Creator: Kaper, H.G.; Leaf, G.K. & Matkowsky, B.J.
Partner: UNT Libraries Government Documents Department

Chelating extractants of improved selectivity. Progress report, September 1, 1976--October 31, 1977

Description: New means of characterizing metal chelating reagent selectivity have been developed and incorporated into a theoretical factor analysis of the chelate stability constants of 24 metal ions with 14 ligands of the EDTA family. The factor analysis will be extended to extracting ligand families. A computer-controlled automated metal chelate stability constant apparatus has been assembled and successfully tested. A high performance liquid chromatograph has been set up and preliminary examination of comparison of reversed phase chromatographic separation of metal ions with their solvent extraction behavior begun.
Date: July 1, 1977
Creator: Freiser, H.
Partner: UNT Libraries Government Documents Department

High speed gel permeation chromatography calibration procedures. Period covered: January--March 1976

Description: A High Speed Gel Permeation Chromatograph (HSGPC) calibration curve was generated by use of approximately 160 calibration runs employing polystyrene and hydrocarbon standards which were fitted by a fifth degree polynomial. Three substances, the peroxide of tetrahydrofuran, o-dichlorobenzene, and HMX were evaluated as internal standards to correct for small fluctuations in flow rate from run-to-run, and were found to be satisfactory. The utility of a composite calibration mixture was also established.
Date: January 1, 1976
Creator: Kohn, E. & Ashcraft, R.
Partner: UNT Libraries Government Documents Department

Device for pressure control of a liquid chromatograph pump

Description: A simple circuit for controlling the delivery pressure of a stepping motor-driven syringe pump is described. This circuit allows a pressure to be set either manually or by computer control and permits controlled increases and decreases in pump pressure. An evaluation of the reproducibility of starting pressures and programming rates resulted in relative standard deviations of better than 1.5 percent and 7 percent respectively. An application of this circuit to supercritical fluid chromatography (SFC) is described.
Date: March 31, 1976
Creator: Van Lenten, F. J. & Rothman, L. D.
Partner: UNT Libraries Government Documents Department

Band broadening studies using the parameters for an exponentially modified Gaussian

Description: The effects on chromatographic peak shape of dead volume and flow rate have been examined using the standard deviation of the Gaussian component of the peak and the exponential decay constant. For a non-retained solute, addition of dead volume led to an increase in the standard deviation that was independent of flow rate while the decay constant was inversely proportional to the flow. Smaller changes were observed for a retained species.
Date: September 1, 1976
Creator: Pauls, R. E. & Rogers, L. B.
Partner: UNT Libraries Government Documents Department

Adsorption on mixtures of ion exchangers

Description: A theoretical study has been made of adsorption on mixtures of ion exchangers. The effect of variables such as the concentration of the ion being adsorbed, the concentration of the supporting electrolyte, loading, the values of the capacities and equilibrium constants for the various exchange processes, and the fraction of each adsorber in the mixture on the observed distribution coefficient has been investigated. A computer program has been written to facilitate the calculation of distribution coefficients for the adsorption of an ion on a given mixture of ion exchangers under a specified set of conditions.
Date: March 1, 1979
Creator: Triolo, R. & Lietzke, M.H.
Partner: UNT Libraries Government Documents Department

Loading and unloading resin from MPPF rapid ion-exchange columns

Description: A process was developed which permits changing the resin in the Multipurpose Processing Facility Rapid Ion Exchange columns, without replacing the entire column assembly. The columns remain on the rack during the resin removal and replacement. The resin displacement process consists of a resin unloading and a resin loading step. During resin removal, the spent resin is hydraulically displaced from the columns to a resin collection tank, and then transferred to the evaporator for dissolution. Fresh resin is loaded into the empty column by hydraulic displacement or a combination of vacuum loading followed by hydraulic displacement. In the hydraulic displacement loading process, the amount of fresh resin needed to load the columns is transferred to a resin displacement tank where the resin is hydraulically displaced to the appropriate column. In the vacuum loading process, part of the resin feed is loaded directly into the column by applying a negative pressure to the column.
Date: October 1, 1981
Creator: Ng, W.C.
Partner: UNT Libraries Government Documents Department

Future directions for separation science in nuclear and radiochemistry

Description: Solvent extraction and ion exchange have been the most widely used separation techniques in nuclear and radiochemistry since their development in the 1940s. Many successful separations processes based on these techniques have been used for decades in research laboratories, analytical laboratories, and industrial plants. Thus, it is easy to conclude that most of the fundamental and applied research that is needed in these areas has been done, and that further work in these ''mature'' fields is unlikely to be fruitful. A more careful review, however, reveals that significant problems remain to be solved, and that there is a demand for the development of new reagents, methods, and systems to solve the increasingly complex separations problems in the nuclear field. Specifically, new separation techniques based on developments in membrane technology and biotechnology that have occurred over the last 20 years should find extensive applications in radiochemical separations. Considerable research is needed in such areas as interfacial chemistry, the design and control of highly selective separation agents, critically evaluated data bases and mathematical models, and the fundamental chemistry of dilute solutions if these problems are to be solved and new techniques developed in a systematic way. Nonaqueous separation methods, such as pyrochemical and fluoride volatility processes, have traditionally played a more limited role in nuclear and radiochemistry, but recent developments in the chemistry and engineering of these processes promises to open up new areas of research and application in the future.
Date: January 1, 1986
Creator: Pruett, D.J.
Partner: UNT Libraries Government Documents Department

Rate phenomena in uranium extraction by amines

Description: Kinetics studies and other rate measurements are reviewed in the amine extraction of uranium and of some other related and associated metal ions. Equilibration is relatively fast in the uranium sulfate systems most important to uranium hydrometallurgy. Significantly slow equilibration has been encountered in some other systems. Most of the recorded rate information, both qualitative and quantitative, has come from exploratory and process-development work, while some kinetics studies have been directed specifically toward elucidation of extraction mechanisms. 71 references.
Date: January 1, 1979
Creator: Coleman, C.F. & McDowell, W.J.
Partner: UNT Libraries Government Documents Department

Separation and characterization of coal derived components. Quarterly report, 1 October 1983-31 December 1983

Description: No new field-ionization data was obtained this quarter. For preasphaltenes, elemental analysis data was obtained on Kentucky and Wyodak preasphaltene samples. In conjunction with the preasphaltene work, solubility and thin-layer chromatography experiments were performed. The results indicated that basic alumina would not be useful as a general stationary phase for the separation of preasphaltenes. Several experiments were carried out with Chromasorb T, and the results showed it would be an adequate substitute for Fluoropak. The hydrocarbons in a sample from Pittsburgh Energy Technology Center were separated by the number of double bonds. The optimum mobile phases for the separation of monohydroxyl aromatics and dihydroxyl aromatics by reversed-phase liquid chromatography were obtained. In addition, a means of predicting retention in normal-phase chromatography was considered, and a NO/sub 2/ high-performance chromatographic column showed promise for the separation of compound classes. 6 references, 4 figures, 7 tables.
Date: January 16, 1984
Creator: Hurtubise, R.H. & Silver, H.F.
Partner: UNT Libraries Government Documents Department

Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications

Description: Significant progress was made toward developing advanced materials for gas separation membrane applications and rationalizing molecular structure and efficacy: Synthesized and tested polyarylates based on terephthalic or isophthalic acid or a tertiary butyl derivative of the isophthalic acid with different diols to illustrate the effects of: opening'' the matrix by incorporation of bulky packing inhibiting groups such as the tertiary butyl moiety inhibition of backbone motion via meta connected backbone connections and tightening'' of the matrix by incorporation of polar halogens. Completed high temperature characterization of sorption and transport properties for novel materials. Continued studies of the phenyl-substituted polymers aimed at producing super stable high temperature useful polymers for gas separations. Synthesized a polyarylate based on the spirobiindane diol and bibenzoyl acid chloride to incorporate long flat packable bibenzoyl units between packing disruptive spirobiindane units in an attempt to control the segmental level morphology to produce highly selective bottleneck'' regions between highly open regions.
Date: December 31, 1991
Creator: Koros, W.J. & Paul, D.R.
Partner: UNT Libraries Government Documents Department

Design and synthesis of reactive separation systems

Description: During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.
Date: January 1, 1992
Creator: Doherty, M.F.
Partner: UNT Libraries Government Documents Department

Chelating extractants of improved selectivity. Progress report for period November 1, 1977--July 31 1978

Description: During the current contract period, the high susceptibility of lanthanide chelate stability to steric hindrance was confirmed. The increase in coordination number of lanthanides from lanthanum to ytterbium as evidenced from extraction equilibria serves to increase their separability. 8-Quinolinol immobilized on silica can separate lanthanide ions.
Date: August 1, 1978
Creator: Freiser, H.
Partner: UNT Libraries Government Documents Department

Parametric study and preliminary evaluation of reverse osmosis for seawater desalination

Description: A parametric study of one- and two-stage reverse osmosis (RO) systems for seawater desalination was made with the aid of a recently developed computer program for optimization of RO systems. Membrane manufacturer's performance data and predicted cost data were applied. Based on these data and other equipment and operating costs considered, a preliminary evaluation of the economics of RO for seawater desalination was made. Plant capacities in the range of 1 to 12.5 Mgd were considered and compared economically with the current most common multistage flash distillation process at different energy price levels.
Date: November 1, 1976
Creator: Glueckstern, P.; Reed, S. A. & Wilson, J. V.
Partner: UNT Libraries Government Documents Department

Capillary liquid chromatography using laser-based and mass spectrometric detection

Description: The DOE-supported research performed during the past year has mainly focused on investigating and minimizing three problems that limit the practical utility of these capillary electrokinetic separation techniques in chemical analysis. (1) Analyses are hindered by poor reproducibility. This is largely a result of complicated and irreproducible capillary wall-solute interactions that often result in adsorption and mobility changes. (2) While the (micellar electrokinetic capillary chromatography) (MECC) technique permits the separations of neutral solutes, hydrophobic compounds are difficult to separate and manipulation of capacity factors (k's) is critically important. (3) The very small solute band volumes require that on-column detection be performed (usually optical detection) and this seriously limits detectability. In addition to these projects, the electrokinetic equivalent of affinity chromatography and development of remote fiber-optic sensors to measure chemical carcinogens and other compounds have been investigated. 5 refs., 2 figs.
Date: January 1, 1990
Creator: Sepaniak, M.J. & Cook, K.D.
Partner: UNT Libraries Government Documents Department

Adsorption of lead from liquid bismuth. [Time, temperature, and lead concentration effects]

Description: The possibility of low temperature absorption of lead from liquid bismuth is investigated. The effects of time, temperature, and the lead concentration in liquid bismuth on distribution of solute in solvent and adsorbent are studied. The results found can be used to study the feasibility of applying adsorption as a means of purifying liquid metals. (JFP)
Date: February 1, 1977
Creator: Chou, Y. C. T.
Partner: UNT Libraries Government Documents Department

Exchange of interlayer cations in micaceous minerals. Final report, February 1, 1967--August 31, 1976

Description: Laboratory experiments were carried out to establish a comprehensive understanding of the processes and factors governing the sorption and release of interlayer cations in micaceous minerals. A diverse approach with several lines of work was used to delineate the effects of different procedures, solution compositions and mineral properties. It was soon clear that the major factors controlling the exchange of interlayer cations are the blocking effects of dissolved fixable cations and the limiting effects of small particles. By using sodium tetraphenylboron to reduce the blocking effects and by excluding particles that were smaller than 2 ..mu..m, however, the subtle effects of many other factors were brought out. The redox status of structural iron, the hydroxyl groups, the interlayer spacing and the layer charge of the minerals are indicative of the type of factors involved and the fact that they are mainly interactive in nature. One conclusion from this work is that most experimental results for interlayer cation exchange are bound to reflect some combination of the controlling factors. More important, however, was the observation that proper management of interlayer cation exchange can make micaceous minerals a good sink for cesium and source of potassium.
Date: August 1, 1976
Creator: Scott, A. D.
Partner: UNT Libraries Government Documents Department

Comparisons of methods for calculating retention and separation of chromatographic peaks

Description: The accuracy and precision of calculating retention times from means and peak maxima have been examined using an exponentially modified Gaussian as a model for tailed chromotographic peaks. At different levels of random noise, retention times could be determined with nearly the same precision using either the mean or maximum. However, the accuracies and precisions of the maxima were affected by the number of points used in the digital smooth and by the number of points recorded per unit of standard deviation. For two peaks of similar shape, consistency in the selection of points should usually permit differences in retention to be determined accurately and with approximately the same precision using maxima, means, or half-heights on the leading side of the peak.
Date: September 1, 1976
Creator: Pauls, R. E. & Rogers, L. B.
Partner: UNT Libraries Government Documents Department

Solvent extraction equipment evaluation study. Part 1. Review of the literature

Description: This is Part 1 of a three-part document that reviews the solvent extraction contactors available for use in radiochemical reprocessing plants. The three parts are: Part 1: A Review of the Literature, Part 2: Workshop Proceedings, Part 3: A Summary. The main objective of the document is to provide an information base to aid in contactor selection and design of future reprocessing plants. The Literature Review (Part 1) brings together scattered data on all major contactors in use today. It contains an annotated bibliography of the citations used in the review and a complete listing of all the citations screened prior to the review. These bibliographies should aid in determining which reports would be most useful if additional information is desired.
Date: January 1, 1977
Creator: Geier, R. G. & Browne, L. M. (comps.)
Partner: UNT Libraries Government Documents Department

Predictive thermodynamic models for liquid--liquid extraction of single, binary and ternary lanthanides and actinides

Description: Chemically based thermodynamic models to predict the distribution coefficients and the separation factors for the liquid--liquid extraction of lanthanides-organophosphorus compounds were developed by assuming that the quotient of the activity coefficients of each species varies slightly with its concentrations, by using aqueous lanthanide or actinide complexes stoichiometric stability constants expressed as its degrees of formation, by making use of the extraction mechanism and the equilibrium constant for the extraction reaction. For a single component system, the thermodynamic model equations which predict the distribution coefficients, are dependent on the free organic concentration, the equilibrated ligand and hydrogen ion concentrations, the degree of formation, and on the extraction mechanism. For a binary component system, the thermodynamic model equation which predicts the separation factors is the same for all cases. This model equation is dependent on the degrees of formation of each species in their binary system and can be used in a ternary component system to predict the separation factors for the solutes relative to each other. (LK)
Date: March 1, 1977
Creator: Hoh, Y. C.
Partner: UNT Libraries Government Documents Department

A theoretical model for adsorption capacities of charcoal beds: I, Relative humidity effects

Description: Water vapor is the major interferent in the adsorption of other vapors from air when that air is passed through an activated charcoal bed. A limited amount of data (published and unpublished) is available on the magnitudes of capacity (or service life) reduction as a function of relative humidity (water vapor concentration) and preadsorbed water. A simple equilibrium model has been developed which quantitatively explains observed humidity effects and allows extrapolation of data to untested conditions. 9 refs., 4 figs., 2 tabs.
Date: January 1, 1987
Creator: Wood, G.O.
Partner: UNT Libraries Government Documents Department

Mathematical model for multicomponent separations on the continuous annular chromatograph

Description: A model for multicomponent separations on ion exchange columns has been adapted for use in studying the performance of the continuous annular chromatograph. The model accurately predicts solute peak positions in the column effluent and qualitatively predicts trends in solute effluent resolution as a function of increasing bandwidth of the solute feed pulse. The major virtues of the model are its simplicity in terms of the calculations involved and the fact that it incorporates the nonlinear solute-resin binding isotherms common in many ion exchange separations. Because dispersion effects are not accounted for in the model, discrepancies exist between the shapes of the effluent peaks predicted by the model and those determined experimentally.
Date: December 1, 1980
Creator: Bratzler, R.L. & Begovich, J.M.
Partner: UNT Libraries Government Documents Department