DOE-BES Chemical Sciences
Highlights of Progress in Separations Sciences
1980-1999

Edited by

Charles H. Byers

IsoPro International Inc.

2140 Santa Cruz Ave, #C304

Menlo Park, CA 94025

Last Modified September 14, 2000

DOE Chemical Sciences

Highlights of Progress in Separations Sciences

Introduction

The singular wartime success of the Manhattan project was, in large part, due to the fact that project chemists, led by Glenn Seaborg, leveraged their understanding of the chemistry of plutonium to industrial scale processes for isolating this man-made element from irradiated fuel. Thus began the intense interest of the Department of Energy and its predecessor agencies in the science that underlies separation processes. The evolving mission of the Department has now come full-circle as the scientific community is enlisted to face the legacy of the Manhattan Project and the Cold War era and to render the accumulated wastes manageable. Knowledge of molecular level processes is required to characterize and treat these enormously complex mixtures and to understand and predict the destiny of associated contaminants in the environment.

Though the Cold War Legacy is the most obvious of the Department missions the economic importance of separation science and technology is huge. For example, in 1979, distillation processes in the petroleum, chemical, and natural gas industries consumed the equivalent of 315million barrels of oil. It was further estimated in the National Academy of Sciences Report cited below that separations processes account for more than 5 percent of total national energy consumption. Separations are essential to virtually all manufacturing operations in the processing industries and are also key to many analytical procedures. Continuing research in this area is of the utmost importance to the national interest. The purpose of the separations component of the Separations and Analysis Program is to develop the understanding needed to enable advances in separation science.

The Separations and Analysis Program is driven by the questions of individual principal investigators: It is not "directed" research. The peer review process guides the selection of questions that are to be pursued. Any fundamental science that addresses questions in the area of separations phenomena that is also consistent with the mission of the Department of Energy is appropriate for the program. The goal is to encourage innovation and creativity and to maintain an attitude of open inquiry.

This document lists some of the accomplishments made possible by the research program over the last 20 years. It is important to keep in mind that all of the advances listed below resulted from the pursuit of knowledge at the most fundamental level. The application of that knowledge to specific problems often enabled major technological innovations. It is a characteristic of basic research that its products often have impact on an unanticipated and broad scale. This characteristic is illustrated in these accomplishments. They serve as a testament to the value of open, undirected research.

Richard L. Gordon, Program Manager, May 18, 2000 Summary

February 7, 2000

During the past several months a gathering of major accomplishments in the research sponsored by Basic Energy Sciences by currently sponsored institutions over the period of DOE's sponsorship has been undertaken. The request for these inputs took the form of a letter to principal investigators making the following request:

"We are seeking all of the examples of consequences of your work including that of your past or present colleagues. These could be:

1. Commercialization of your ideas or developments,

2. Use of your research in a scientific application that has been beneficial to society,

3. Any development that has led to paradigm-changing understanding,

4.Any development that has led to improvements in applications or practice."

Responses were collected from the majority of current principal investigators (PI). The input varied greatly in style and content, some focusing on one of the requested areas and others showing progress over the entire spectrum. This report is divided into sections using the original request as a guideline in subdividing the document. Therefore some of the reports were subdivided and placed in multiple sections. The name of the PI accompanies each report with the team details and addresses compiled at the end of the document.

Charles H. Byers, Editor, February 7, 2000

Table of Contents

Commercialized Research Results. 5

Commercialized Technologies. 5

Uranium From Phosphate Rock Processing ( ORNL)5

Commercialization Of CO₂-Based Green Chemistry (Hank D. Cochran)5

Cleanup of High-Level Waste Benefits from Fundamental Studies on Crown Ethers (Bruce Moyer)6

Crown Ethers for Removing Technetium from Alkaline Waste Solutions (Bruce Moyer)8

Basic Research Reduced Cost of Uranium Production (Bruce Moyer)9

Low Fouling Ultrafiltration and Microfiltration Aryl Polysulfone (Georges Belfort)11

DEPA-TOPO (ORNL)11

Separation of Lanthanides (Ames Lab)11

Zirconium-Hafnium Separation (ORNL -Ames)11

The Calutrons - Isotope Separations (ORNL)12

Fast Fluid Analyzer (ORNL)12

Continuous Annular Chromatography (ORNL)12

Emulsion Phase Contactor (David DePaoli)13

Dielectric Filter (David DePaoli)13

Micelles and Microemulsions in Supercritical Fluids ( ClemYonker)13

Stabilized Expanded Bed (David DePaoli)14

Products in Commerce. 14
Aqueous Diphonix: A New Ion-Exchange Resin for the Removal of Radioactive and Hazardous Metal Ions from Solution (Mark L. Dietz). 14

A New Generation Of Selective Polymer Beads (Spiro Alexandratos)14

Bifunctional Anion Exchange Resin for Groundwater Cleanup (Bruce Moyer)14

Surfactants For Dry Cleaning (Keith Johnston)16

Insoluble Drug Formulations (Keith Johnston)16

Separation Methods Technologies, Inc.(Mary Wirth)16

Commercialized Techniques. 16

Solvent-Extraction Research Provides Basis for Commercialization of Sensitive Analytical Methodology (Bruce Moyer)16

Sensitive Instrumentation for Measuring Radionuclides has Revolutionized Radioanalytical Laboratories (Bruce Moyer)17

Evaporative Light Scattering Detector For HPLC (Georges Guiochon)17

Polymer Chain Growth On Surfaces (Mary Wirth)17

Laser-Based Detectors For Liquid Chromatography (Ed Yeung)17

Ionization Laser Vaporization for Mass Spectrometry (Ed Yeung)18

Applications of Small Drop Generation Technology (Basaran)18

High-Temperature Fiberoptic Spectroscopic Instrumentation for the Magnesium Industry (Sheng Dai)18

Spectroscopic Sensors for the Aluminum Industry (Sheng Dai)18

Spectroscopic Titanium Complex Sensors for the Titanium Industry (Sheng Dai)18

Research Beneficial to Society. 18

Beneficial Technologies. 19

Principle of Bifunctionality (Spiro Alexandratos)19

Room Temperature Ionic Liquids (Robin Rogers)19

Synergism Changes Course of Research on Crown Ethers for Extraction of Metal Ions (Bruce Moyer)20

. 20

SREX : A New Process for the Extraction and Recovery of Radiostrontium from Acidic High Level Liquid Wastes (Mark L. Dietz). 20

Beneficial Techniques . 19

Technical Consulting Impact of ORNL Actinide Program (Sheng Dai)20

Surface Chemistry Details of Alkyl Carboxylate Adsorption (Jan Miller)21

Flotation Of Fine Particles in a Centrifugal Field (Jan Miller)21

Catalyst Reactivity and Separations using H₂O/CO₂ Emulsions (Keith Johnston)21

Filtering Protein Solutions (Georges Belfort)22

Paradigm-changing understanding.24

Host-Guest Complexation (Donald Cram).24

Solvation In Supercritical Fluid Systems, a Molecular View (Frank V. Bright)24
Ion-Water Structure in Hydrothermal Water (ClemYonker)24
Center for Green Manufacturing (Robin Rogers)26
NSF Science and Technology Center for Environmentally Responsible Carbon Dioxide Processes (Keith Johnston)27
Adsorption Energy Distribution (Georges Guiochon)27
Affinity of a Surface Substrate for a Protein (Georges Belfort)28
Single-Molecule Diagonistics Reveal Mechanism of Chromataographic Separations (Ed Yeung)28
High Sensitivity Infrared Spectroscopy of Silica/Solution Interfaces (Joel M. Harris)28
Relaxation Methods to Measure Sorption/Desorption Rates (Joel M. Harris)28
Application of Molecular Recognition to Capillary Scale Separations (Michael Sepaniak)28
Fission Product Separation using Room Temperature Ionic Liquids (Sheng Dai)29

Improvements in Applications orPractice. 30
In Situ FTIR Internal Reflection Spectroscopy (Jan Miller)30
DNA Hybridization using a New Polymer Chain Growth Method (Mary Wirth)30

Packing Density Homogeneity In Chromatographic Columns (Georges Guiochon)

Flotation of Mineral Particles From Saturated Brines (Jan Miller)

Analysis of the Long Range Hydrophobic Attractive Force (Jan Miller)

Emulsification of Water and CO₂ with Surfactants (Keith Johnston)

Program for Modeling Liquid-Liquid Extraction Data (Bruce Moyer)

Exploration of Fluorescence Lifetime Measurements (Linda McGown)

Viscous Fluid Overturn during Rupture (Osman Basaran)

Satellite Drop Elimination (Osman Basaran)
High Pressure NMR (Yonker)33

Conclusions

Appendix A: Contributors

Spiro D. Alexandratos

Keith P. Johnston. 35

Michael J. Sepaniak. 36

Mary J. Wirth,36

Edward S. Yeung. 36

Clement R. Yonker .36

Appendix B: Request Letter36

Appendix C: A Brief History of DOE Chemistry Support 36

DOE Chemical Sciences

Commercialized Research Results

Under this title, we can conceive of three sub headings: the implementation of a technology that finds its roots in the Separations and Analysis Program, the making of products that find their roots in the program and techniques that have been adopted by industry as part of their general practice.

Commercialized Technologies

Over the years many of the ideas that have been turned into technologies have been adopted commercially.

Uranium From Phosphate Rock Processing (ORNL)

Basic Energy Sciences research provided the scientific knowledge and the patented methods which subsequently enabled the efficient extraction of uranium as a valuable byproduct of the phosphoric acid manufacturing process. Large manufacturing plants in Florida and Louisiana, representing about half of the industry’s phosphate rock processing capacity, recovered uranium using methods based on this original work. The key to an efficient separation process was the development of an “extractant,” with a strong preference for the uranium found in acid solution, which was characteristic of phosphate rock processing.

Commercialization Of CO₂-Based Green Chemistry (Hank D. Cochran)

New "green chemistry" approaches, which substitute benign carbon dioxide for noxious industrial solvents, have made it to the big time with announcements of commercial deployment of CO₂-based dry cleaning technology by Micell Technologies, Inc. and CO₂-based industrial production of Teflon polymers by E. I. DuPont de Nemours and Company. The research, which ultimately led to commercial success, was pioneered by Professor Joseph DeSimone of the University of North Carolina and North Carolina State University, including polymer synthesis in CO₂ and the use of CO₂-based surfactants or detergents. The pursuit of CO₂-based green chemistry has benefited enormously from the basic research facilities and expertise of several DOE/BES research programs--at Pacific Northwest Laboratories with Richard Smith and John Fulton, at the University of Texas with Keith Johnston, at Oak Ridge National Laboratory with George Wignall and Hank Cochran, and others. This success story is a tribute to the effectiveness of the partnership of basic research, using the most powerful tools in the world, with applied research and development involving universities, national laboratories, and industry.

Cleanup of High-Level Waste Benefits from Fundamental Studies on Crown Ethers (Bruce Moyer)

Fundamental research at Oak Ridge National Laboratory has set the foundation for the development of a new solvent extraction process for separating radioactive 137cesium (137Cs) from the Department of Energy high-level wastes. These wastes, remaining from the production of nuclear weapons dating back to the Manhattan Project, are being stored in underground tanks at USDOE sites such as Hanford and Savannah River. There is currently a search for a set of technologies that everyone agrees will satisfactorily separate out the chief radioactive contaminants for vitrification and final disposal.One of the most tenacious technical problems is the separation of 137Cs, which together with 90Sr, accounts for most of the radioactivity in the waste. Typical "tank wastes" consist primarily of sodium salts with a trace of cesium, on the order of 1/100,000th of the concentration of sodium.The problem is that 137Cs is so radioactive that, even in this trace concentration, up to 99.999% must be removed to achieve a satisfactory decontamination. This is a stringent demand requiring extraordinary selectivity.

Since the promising discovery in 1967 that crown ethers could selectively bind alkali metals, scientists have regarded these large cyclic molecules as a possible solution to the decades-old cesium decontamination problem. Until recently however, no compound of this type has possessed sufficient selectivity and extraction strength. This changed with the advent of new calixarene-crown compounds in Europe. Even so, key gaps in fundamental knowledge stood in the way of developing a functional industrial process. Contributions toward this end came from ORNL. First, a soluble calixarene-crown extractant would have to be synthesized. Techniques discovered in basic research made possible ORNL's cesium extractant shown here, called "BOB Calix". The extractant is shown together with a positively charged ion of cesium (Cs+) inside one of its cavities. As shown more precisely in the 3-dimensional structure above, the rather precise fit of the Cs⁺ ion in the cavity gives rise to the remarkable selectivity for Cs+ ion.Making BOB Calix function properly required understanding the molecular details of its extraction and subsequent release of Cs+ ions.A critical step was the use of special fluorinated alcohols that enhance BOB Calix's extraction strength, allowing the expensive extractant to be effective at economical concentrations.

One of the alcohols is shown to the right. Understanding the details of the chemical reactions taking place through mathematical modeling of extraction data then revealed how to make the complex release its bound Cs+. This closed the cycle allowing the solvent to be used over and over again.

The resulting process, now referred to as the alkaline-side CSEX process, is so effective that the stringent decontamination and concentration requirements set at the Savannah River Site (SRS) for removal of more than 99.99% of the cesium in the waste are expected to be readily met. Recently, the process was selected as one of four top technologies for possible application at SRS where the process was shown in engineering evaluations to be competitive with the alternative technologies. One of the recognized advantages of alkaline-side CSEX is that the process would give a product stream that contains nearly pure cesium nitrate, an ideal feed for subsequent vitrification with concomitant major cost savings. The purity of the 137Cs product also suggests possible uses in gamma sources for industrial applications. A patent application is pending and the production of BOB Calix has been successfully transferred to the private sector (IBC Advanced Technologies). A 1999 Lockheed Martin Technical Accomplishment Award recognized this work. Applied and fundamental studies related to alkaline-side CSEX are continuing.

The foundation leading to this development was provided by basic research supported by the USDOE Office of Basic Energy Sciences, Chemical Sciences Division. More targeted studies have been carried out under the USDOE Environmental Science Program. Process development was supported under the USDOE Office of Technology Development, Efficient Separations and Processing Integrated Program.

Crown Ethers for Removing Technetium from Alkaline Waste Solutions (Bruce Moyer)

A combination of fundamental principles and process development has led to a remarkable method for extracting heptavalent technetium (Tc) from alkaline nuclear-waste solutions by the use of crown ethers. Technetium is a long-lived radioactive fission product found in wastes stored at several DOE sites. Almost two metric tons of Tc are stored in underground tanks at the Hanford site where it is planned to separate the Tc from the 55 million gallons of other waste components in the tanks. In the long term, Tc represents a concern owing to its environmental mobility in the form of pertechnetate anion and likely health risk for hundreds of thousands of years to come. Technetium also represents a short-term concern owing to its volatility which causes difficulties in vitrification processes proposed for nuclear waste. Research in the Chemical Separations Group of the Chemical and Analytical Sciences Division at ORNL has recently suggested extractive methods that could be used to remove Tc from the highly salted wastes stored in the tanks. Although it had been well known that crown ethers possess the ability to efficiently extract sodium salts by binding the sodium ion, a key question of interest at ORNL concerns what factors determine which salt would be extracted selectively from a mixture of sodium salts.

SRTALK process for removing technetium from nuclear waste

A fundamental understanding of the thermodynamics of such systems in fact led to the prediction that sodium pertechnetate could be selectively separated from the Hanford waste. In subsequent process development, this prediction was validated through invention of the SRTALK process. No pre-treatment of the waste solution is necessary, and the technetium can be recovered using a safe and inexpensive stripping process, regenerating the crown ether for many more cycles with minimal generation of secondary waste. Engineering tests with a waste simulant in a cascade of centrifugal contactors by collaborators at Argonne National Laboratory gave 89% removal of Tc from the waste, meeting the experimental goal. Remarkably, the tests gave a product stream concentrated 10-fold in sodium pertechnetate. Considering that the source of the recovered Tc would be a substantially toxic and complex waste, the remarkable purity of the Tc product would make for an ideal feed for production of waste forms for final disposal, with expected major cost savings. Given the product purity, a practical application may be found.

A chemical depiction of SRTALK is shown above. The waste is a mixture of salts concentrated in sodium, potassium, hydroxide, nitrate, nitrite, and carbonate, but with a trace of radioactive contaminants such as 99Tc. Most of the Tc is in the form of the negatively charged pertechnetate ion, which has the formula TcO4^-. The crown ether complexes with sodium ions (Na+) as shown but can also complex with potassium ions (K⁺). The transfer of either of these metal ions into the solvent by the crown ether must also be accompanied by a negatively charged ion. Among the most easily transferred negative ion is pertechnetate with a selectivity over nitrate on the order of a thousand to one. When the solvent is contacted with water the sodium pertechnetate may be released into the water, regenerating the crown ether for further extraction cycles. The process is described by a 1995 patent and in numerous publications. The governing fundamental principles are described in a series of papers from the early 1990s continuing to the present. In 1999 a Lockheed Martin Technical Accomplishment Award recognized the development of the SRTALK process.

The foundation leading to this development was provided by basic research supported by the USDOE Office of Basic Energy Sciences, Chemical Sciences Division, and the process development was supported under the USDOE Office of Technology Development, Efficient Separations and Processing Integrated Program.

Basic Research Reduced Cost of Uranium Production (Bruce Moyer)

During the 1980s, U.S. uranium mills were able to reduce their costs as a result of fundamental understanding of molybdenum extraction gained in research at Oak Ridge National Laboratory. This understanding was important because molybdenum is often co-mineralized with uranium in ore and represents both a processing problem and potential by-product in uranium recovery. Common processing interferences in the solvent extraction of uranium from ore leach solutions arise from coextraction of molybdenum followed by troublesome precipitation of crystalline compounds in the solvent extraction equipment in the mills. Fundamental research revealed the identity and structure of the complexes formed in the extraction of molybdenum and the factors that controlled crystallization of these compounds. This information helped extractant manufacturers to improve their products and services by supplying the uranium mills with extractants tailored for higher molybdenum concentrations. In addition, U.S. uranium producers benefited directly by application of appropriate process controls to avoid costly sludge formation at several U.S. uranium mills. For example, controls demonstrated in 1986 at Chevron's Panna Maria facility produced annual savings of almost $300,000. Sometimes studying a particular problem gives insights into general chemical behavior, and interestingly, the understanding of molybdenum extraction has led to an improved understanding of a broad class of separations.

The extractant in this case belongs to a class of nitrogen compounds known as amines and contains three hydrocarbon chains. In its effective form, this amine has an additional hydrogen atom to give it an overall positive charge.The resulting ammonium ion must have a negative ion nearby.

In extractions, usually this anion is exchanged for a larger anion. A structure for a common type of extraction complex formed in such extractions is shown in the figure. This complex consists of the long-chain ammonium ions and two anions X^- and Y^- of different sizes. The small anion X^- receives two hydrogen bonds from a pair of ammonium ions, and the larger anion Y^- receives none. In the molybdenum problem studied at ORNL, the small anion was chloride Cl^- and the large anion had the complicated formula PMo₁₂O₄₀^3-. The entire complex contained this large anion, three chloride ions, and six ammonium ions. Unfortunately, an X-ray structure of this unwieldy complex could not be obtained, but the general structure shown at right was in fact demonstrated for the first time on a related compound. The latter has two tributylammonium ions, one chloride, and one tetraphenylborate. Thus, an investigation related to a real-world problem explained a great deal about an important class of separations.

Low Fouling Ultrafiltration and Microfiltration Aryl Polysulfone (Georges Belfort)

Although Rensselaer Polytechnic was awarded a US Patent on work done prior to DOE funding (G. Belfort, Jim Crivello and Hideyuki Yamagishi, " Low Fouling Ultrafiltration and Microfiltration Aryl Polysulfone", Patent Number #5,468,390, Issued: 11/21/95), during the period of the current DOE grant, surface development work was conducted using photooxidation and low temperature plasma. Several US and foreign companies have expressed interest in this work and the patent. They include Millipore Corp, Bedford MA, Pall Corp., Gelman Division, Pensacola, FL, and PTI, Corp., Thousand Oaks, CA.

DEPA-TOPO (ORNL)

At Oak Ridge National Laboratory, based on a long research history in uranium chemistry, investigators supported by the DOE Basic Energy Sciences program undertook the study of uranium separations chemistry. An agent that converts uranium to a tetravalent state from the hexavalent form was required. In 1972, these researchers reported that they had developed a combination of two stable extractants with improved capabilities for stripping uranium from the phosphoric acid production process. Together, they were known as DEPA-TOPO, after the two extractants, Di 2-Ethylhexl Phosphoric Acid and Tri-n-Octyl Phosphine Oxide. The actions of the two extractants were found to be synergistic in that they worked together much more effectively than either did individually. So well did they work in this manner that almost 90 percent of the uranium originally in the phosphate rock solution was recovered when the process was used. This technology rapidly entered commercial practice.

Separation of Lanthanides (Ames Lab)

Chemically, the 15 naturally occurring rare earth elements are virtually indistinguishable from one another. As a result they are found co-mingled in rare earth-bearing ores and are difficult to separate. BES scientists developed the separation technology that allows the production in pure form of all the rare earths, and this technology provided for the first time easy access to rare earths in pure elemental form. Their availability led to a virtual explosion of new and advanced applications. Rare earths, when combined with certain other elements, form metal alloys having unusual magnetic properties. The red elements of color television pictures, for example, emanate as colored light from rare earth phosphors. Compact starter motors in automobiles make use of powerful rare earth-based magnets. Such magnets also make possible the miniaturization of magnetic tape readers, popularized in the so-called “walkman” audio cassette players. Some rare earth lasers are used to cut steel. Others surgically repair tissues of damaged or diseased eyes. Rare earth materials are used as well in advanced defense warning systems to detect submarines at great distances. In the United States alone 17,000 tons of rare earths are used annually, all based on the basic technologies originally developed by Basic Energy Sciences researchers. Column chromatographic methods were developed at Iowa State University, Ames Laboratory, allowing small quantities of pure lanthanides to be recovered. The development of complexing agents allowed the use of displacement technology in chromatographic columns, leading to much higher capacity.

Zirconium-Hafnium Separation (ORNL -Ames)

Basic Energy Sciences research made numerous contributions to the development of commercial nuclear power, particularly in the development of special materials used in the internal construction of nuclear reactors. One of the important chapters in these developments is the use of zirconium, which in pure form is transparent to neutrons and was very useful as the alloy zircalloy. Hafnium, zirconium's twin chemically, has the opposite neutron absorbing properties, so must be completely removed to take advantage of zirconium's properties. Building on the fact that workers at Ames Laboratory discovered that silica gel selectively removed hafnium from a solution of the tetrachlorides of zirconium and hafnium in methyl alcohol, researchers at Oak Ridge National Laboratory modified an existing process, called the Fischer thiocyanate process, and applied it to a new continuous flow zirconium separation process. This modified process, known generically as a solvent extraction process, was similar to another method used at Oak Ridge to extract uranium from plutonium. The commercialization of this process depended on two unrelated areas of basic research. First, the investigators had to find a suitable solvent which was methylisobutyl ketone. Second, they had to determine the optimum conditions under which the process would work. This process was then scaled up to a pilot plant, and eventually to a commercial production facility capable of producing about

DOE-BES Chemical Sciences Highlights of Progress in Separations Sciences 1980-1999