EXTRACTION OF POLAR POLLUTANTS USING SUPERCRITICAL FLUIDS AND ENHANCED-FLUIDITY LIQUIDS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Tricia Susan Reighard, B.S. ^ ^ ^ ^ t The Ohio State University 1996 Dissertation Committee: Approved by Professor Susan Olesik, Adviser Professor Richard McCreery Adviser Professor Philip Grandinetti Department of Chemistry UMI Number: 9639336 UMI Microform 9639336 Copyright 1996, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 ABSTRACT Supercritical fluid extraction (SFE) is developing as a viable method for the removal of pollutants from environmental matrices. However, C 02, the most commonly used extraction fluid, is limited in its ability to solvate high molecular weight and/or polar analytes. The addition of 1-10% organic modifier often helps considerably, although less than quantitative results are frequently reported. Enhanced-fluidity liquid extraction (EFLE) is investigated herein as a means of extending the range of SFE for polar pollutants. An enhanced-fluidity liquid is a mixture consisting of a large proportion (10-50%) of a common organic solvent and a high fluidity, low viscosity liquid such as C 02. The mixture is used in the single phase liquid region of the respective cosolvent/C02 phase diagram. Phase transitions were determined for extraction fluids of interest using a high pressure, variable volume view cell. The single phase liquid or supercritical fluid regions were mapped across the 0-1 mole fraction C 02 range for methanol/C02, acetonitrile/C02, methanol/H20/C 02, and acetonitrile/H20/C 02. Phenolic and nitroaromatic pollutants were first extracted from an octadecyl polysiloxane sorbent to compare the mass transport properties of enhanced-fluidity liquids relative to supercritical fluids and conventional liquids. The enhanced-fluidity liquids behaved similarly to the supercritical fluids tested. House dust was then evaluated as an extraction matrix. Pollutants that are “tracked in” to homes and other buildings may adsorb to house dust, a matrix with a high H20 and organic content, and persist for extended periods of time when natural degradation pathways such as sunlight, weather, and microorganisms are reduced or eliminated. The phenolics and nitroaromatics were most efficiently extracted with enhanced-fluidity liquid methanol/H20/C 02 mixtures. Phenoxyacid herbicides were also extracted from house dust using C 02 and methanol/C02 mixtures. The use of 20/80 mole % methanol/C02 at supercritical conditions yielded the highest overall recoveries. Finally, a literature review of other alternative extraction techniques developed over the past five years is presented. Like EFLE, these techniques attempt to bridge the gap between the conventional liquid-solid and liquid-liquid techniques and SFE. To Mom, Dad, and Boo with love iv ACKNOWLEDGMENTS I wish to thank my advisor, Dr. Susan Olesik, for the opportunity to work on projects that I thoroughly enjoyed and for her patience and guidance despite our very different personalities. Thank you to the Olesik group members, past and present, for their technical assistance, encouragement, and friendship during my tenure. I am greatly indebted to my parents, Terry and Sandy Reighard, and my aunt, Pearl Stafford (Boo), for their continual support of my seemingly endless educational pursuits. I would never have made it without their Sunday night phone calls, gifts, prayers, and love. A very special thank you to Gene Ohler for providing a stable and constant source in my life during the often trying days of graduate school. From advice on organic chemistry to the many walks through the town, I truly appreciate his friendship and concern. Ohio would have been a much worse place without him in it. Last, but by no means least, I thank the Lord for the strength, courage, and perseverance needed to make it through the past five years that brought this dissertation from a dream to a reality one day at a time. v VITA April 23, 1969 ................................................ Bom - Johnstown, PA 1991 ..................................................................B.S., Chemistry, University of Pittsburgh, Pittsburgh, PA 1991-1996 .......................................................Graduate Fellow and Research Associate, Department of Chemistry, The Ohio State University, Columbus, OH PUBLICATION Reighard, T.S.; Olesik, S.V., “Comparison of the extraction of phenolic and nitroaromatic pollutants using supercritical and enhanced-fluidity liquid methanol-CO, mixtures.” J. Chromatogr. A1996, 737, 233. FIELDS OF STUDY Major Field: Chemistry Analytical chemistry including supercritical fluid extraction and gas chromatography, performed under the supervision of Dr. Susan Olesik. TABLE OF CONTENTS DEDICATION..................................................................................................................... iv ACKNOWLEDGMENTS...................................................................................................v VITA .................................................................................................................................... vi LIST OF TABLES...............................................................................................................xi LIST OF FIGURES.......................................................................................................... xiv CHAPTER PAGE 1. INTRODUCTION............................................................................................ 1 Steps in Extraction Processes .................................................................... 1 Liquid-Solid Extraction Techniques ........................................................ 3 Supercritical Fluid Extraction (S F E ) .......................................................... 4 Enhanced-Fluidity Liquid Extraction (EFLE) ....................................... 10 Goals of this Research ............................................................................. 15 References ................................................................................................ 18 2. PHASE DIAGRAM DETERMINATION FOR METHANOL/C02) ACETONITRILE/COj, METHANOL/H20/C 0 2, AND ACET0NITRILE/H20/C 0 2 MIXTURES ................................................... 21 Introduction .................................................................................................21 Previous Phase Diagram Studies with Methanol, Acetonitrile, H20, and C02 ........................................................................................ 22 Goals of this Study ................................................................................23 Experimental ............................................................................................ 25 View C e ll............................................................................................ 25 vii Temperature Measurement and Control ................................................ 29 Pressure Measurement .........................................* ............................... 30 Sample M ixing .................. 31 Mixture Preparation ............................................................................... 32 Experimental Procedure ......................................................................... 35 Results and Discussion .................................... 36 Carbon Dioxide ...................................................................................... 36 Methanol/C02 ........................................................................................... 37 Acetonitrile/C02 ........................................................................... 46 Comparison of Methanol/C02 and Acetonitrile/C02 Phase B eh av io r.................................................................................................... 49 Methanol/H20/C 02 .................................................................................. 51 Acetonitrile/H20/C 02 ................................................................................66 Comparison of Methanol/H20/C 02 and Acetonitrile/H20/C 02 Phase B eh av io r.......................................................................................................69 Summary ........................................................................................................ 71 References ...................................................................................................... 85 EXTRACTION OF PHENOLIC AND NITROAROMATIC POLLUTANTS FROM AN OCTADECYL POLYSILOXANE SORBENT USING C02 AND METHANOL/C02 MIXTURES............................................................. 88 Introduction .......................................................................................................88 Previous Extractions of Phenolic and Nitroaromatic Pollutants .. 89 Goals of this Study .................................................................................. 93 Experimental .................................................................................................. 94 M aterials.......................................................................................................94 Soxhlet Extractions ............................................................................... 95 SFE and EFLE Experiments ..............................................................