INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the tact directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter free, while others may be from any type o f computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one ocposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6” x 9” black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. UMI A Bell & Howell Information Company 300 North Zeeb Road, Arm Arbor MI 48106-1346 USA 313/761-4700 800/521-0600 A MECHANISTIC STUDY OF SORPTION OF IONIC ORGANIC COMPOUNDS ON PHYLLOSILICATES DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Sandip Chattopadhyay ***** The Ohio State University 1997 Dissertation Committee: Approved by Dr. Samuel J. Traina (Adviser) Dr. Jerry M. Bigham Dr. Yu-Ping Chin Adviser Dr. Cliff T. Johnston Environmental Science Graduate Program UMI Number: 9731599 Copyright 1997 by Chattopadhyay, Sandip All rights reserved. UMI Microform 9731599 Copyright 1997, 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 Copyright by Sandip Chattopadhyay 1997 ABSTRACT Nitrogen heterocyclic compounds (NHCs) are present in many wastes generated by the use of everyday consumer products. These ionic organic contaminants are adsorbed by the clay fraction of the soil, indicating that adsorption by clays controls their fate in the environment. In order to determine the fate of these organic contaminants in the environment, effort was made to study the sorption characteristics of two model sorbates, which were acridine and acridine-9-carboxylic acid. Well-characterized phyllosilicates (hectorite, saponite, and muscovite) were used as sorbents. The effect of the presence of a cationic surfactant (hexadecyltrimethylammonium bromide) on the sorption behavior of the chosen sorbates was also investigated. Results obtained indicated that clay particles act as templates for the formation of stable aggregates of sorbed molecules. The cationic forms of the NHC molecules were attracted preferentially by the negatively charged clay surfaces over the neutral, zwitterionic and the anionic forms of the organic molecules. Organic molecules were sorbed not only on the external surface but also on the interlayer space of the swelling-type clays. Thermodynamics of the sorption process was also investigated to distinguish between the contributions made by the hydrophobic and the electrostatic forces. It was found that approximately half of the total change in free energy occurring during the process of sorption is due to hydrophobic interactions. Hydrophobic interactions are significant at high concentrations when sorbed molecules form aggregates. The presence of HDTMA dictates the mobility of NHCS in the environment. Results showed that sorbed surfactant molecules increased the amount of organic sorbed, whereas micelles of HDTMA, present at high concentrations, increase the mobility of organic molecules. Finally, the degree of sorption was found to be dependent on the nature of the participating sorbates and sorbents, and also on the prevailing chemical conditions. A comprehensive understanding of the sorption process can be useful to model the fate and transport of ionic organic compounds in soil and aquatic environments. Ill ACKNOWLEDGMENTS I would like to take this opportunity to express my sincere gratitude to my advisor. Dr. Samuel J. Traina for his valuable advice, guidance and continued support during the course of this study. I am deeply grateful to Dr. Jerry M. Bigham for his guidance and free access to his lab and facilities. His advice on mineralogy aspect of my project was invaluable. I am also obliged to Dr. Cliff T. Johnston who allowed me to conduct microcalorimetric experiments in his lab. His feedback as an examination committee member and as an adviser to this project proved extremely useful. I would like to thank Dr. Yu-Ping Chin for suggestions and comments. I also like to thank Dr. Terry J. Logan and Dr. Olli Tuovinen for their help and advice. I like to acknowledge the instrument grant received from US EPA and the financial grants received from Sigma Xi, The Clay Minerals Society, and The Ohio State University Graduate Student Alumni Research awards. I am thankful to Ubaldo Soto for helping me in XRD measurements and BET analyses and Foon-Yee Chong from Purdue University for her help in conducting the microcalorimetric experiments. During my tenure at the Ohio State University, I have met and made a lot of friends who have not directly impacted my research, but have helped me and commiserated with me, and made my life bearable and sometimes, even fun. I cannot possibly mention every one of them, but, I like to mention a few of them. I thank Dr. Valérie Laperche, Dr. Satish Myneni, Jagat Adhiya, Alex Stone, Marion Brill, Ed O’Loughlin, Doug Beak, Stephanie Zamzow, Brenda Swank for their friendship and encouragement. iv I also express my sincere gratitude to my parents and in-laws and my brother (Parthasarathi), sister (Dalia), and brother-in-law (Anupam) for their love, support and understanding. I appreciate all the support and love of my wife, Devamita. Finally, my inspiration is my beautiful daughter, Shreya. VITA 1984 B.E., Chemical Engineering Jadavpur University, Calcutta, India 1984-1990 Design and Process Engineer Development Consultants' Limited, Calcutta, India 1986-1989 MBA, Operations Research Institute of Business Management, Jadavpur University 1990-1992 MS, Chemical Engineering Ohio University, Athens 1992-1993 Research Assistant NSF-Industry-University Center for Corrosion and Multiphase Fluid Flow, Ohio University, Athens 1993-present Teaching/Research Assistant The Ohio State University, Columbus, OH FIELDS OF STUDY Major Field: Environmental Science Chemical Engineering VI TABLE OF CONTENTS Page ABSTRACT......................................................................................................................... ii ACKNOWLEDGMENTS................................................................................................... iv VTTA..................................................................................................................................... vi TABLE OF CONTENTS.................................................................................................... vil LIST OF TABLES.............................................................................................................. xii LIST OF FIGURES............................................................................................................. xiü CHAPTERS 1. Introduction .................................................................................................................... 1 1.1 Introduction .................................................................................................. l 1.2 Assumptions ................................................................................................. 4 1.3 Objectives..................................................................................................... 5 2. Materials and methods .................................................................................................. 8 2.1 Introduction .................................................................................................. 8 2.2 Sorbates ........................................................................................................ 9 2.2.1 Acridine......................................................................................... 9 2.2.2 Acridine-9-carboxylic acid ........................................................... 14 vii 2.2.3 Hexadecyltrimethylammonium bromide ...................................... 16 2.3 Sorbents ......................................................................................................... 18 2.4 UV-visible and fluorescence spectroscopic measurements ....................... 23 2.4.1 Overview......................................................................................... 23 2.4.2 Procedure ......................................................................................... 26 2.4.3 Applications ................................................................................... 29 2.4.3.1 pH effects ........................................................................... 30 2.4.3.2 Molecular aggregation