Investigation of Room Temperature Ionic Liquids as Environmentally Benign Solvents for Industrial Separations (TSE99-A)

EPA Grant Number: R828257
Title: Investigation of Room Temperature Ionic Liquids as Environmentally Benign Solvents for Industrial Separations (TSE99-A)
Investigators: Rogers, Robin D. , Katritzky, Alan R.
Current Investigators: Rogers, Robin D.
Institution: University of Alabama - Tuscaloosa , University of Florida
Current Institution: University of Alabama - Tuscaloosa
EPA Project Officer: Karn, Barbara
Project Period: May 1, 2000 through April 30, 2003
Project Amount: $375,000
RFA: Technology for a Sustainable Environment (1999) RFA Text |  Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development


Room temperature ionic liquids are emerging as novel replacements for volatile organic compounds traditionally used as industrial solvents, however, the basic science involved with fully characterizing these systems may be artificially holding back utilization of these green solvents. The work proposed here will generate new data leading to the development of a fundamental scientific-engineering knowledge base in RTIL properties (with particular emphasis on their use in separations), a prerequisite to the development of new pollution prevention technologies using RTIL. Objectives:

The major long range goal of this project is to understand the physical, chemical, and solvating properties of RTIL from the perspective of enabling the successful replacement of conventional solvent methodologies based on VOCs. This goal includes the following elements:

  • Develop testing protocols for accumulation of basic physico-chemical data
  • Examination of issues such as toxicology, water immiscibility, and leaching
  • Utilization of physical properties to predict properties of new RTIL using CODESSA
  • Examination of RTIL solvent properties using solvatochromic techniques
  • Collection of data with which to develop both empirical and fundamental molecular models applicable to the description of solute partitioning behavior in RTIL
  • Examination of the influence of RTIL structure on the nature and efficiency of forward and back extraction of organic and inorganic solutes
  • Examination of kinetic issues related to the real world application of RTIL by investigation of mass transfer between the phases and the kinetics of complex formation in RTIL


A concerted effort will be mounted to obtain the necessary fundamental scientific and engineering data needed to both understand these systems and for the rational design of RTIL medium for industrial applications. The chemical engineer will require a range of physical and physico-chemical parameters for design purposes, the separations scientist a range of solute descriptors in order to select the appropriate RTIL for a particular application, the synthetic chemist a range of solubility data, and the industrialist, toxicity data and realistic cost projections. The research proposed represents the first steps toward building such a database of fundamental knowledge for RTIL as solvents.

    a) Choice of RTIL Systems for Study. The initial selection of RTIL systems will be based on structural variations of the N-alkylpyridinium and 1-alkyl-3-methylimidazolium cations, and anions which impart both moisture stability and water immiscibility.

    b) Development of Testing Protocols. We will develop a testing protocol for each RTIL studied, including those synthesized in our laboratories, those which become commercially available, and those sent to us by collaborating scientists

    c) Water Content, Ion Leaching, and Miscibility Regimes. Each synthesized ionic liquid will be screened for water content, ion leaching, and miscibility regimes with cosolvents after extensive equilibration with representative aqueous phases.

    d) Physical Property Prediction of RTIL Using CODESSA. In collaboration with Professor Alan Katritzky (University of Florida), we will utilize the physical property data from the training set of RTIL discussed above as input to the program CODESSA to predict properties of new RTIL.

    e) Solvent Property Characterization. It is proposed to examine the solvent properties of simple RTIL in some detail and to examine the applicability to ionic solvents of current molecular modeling methods normally applied to molecular solvents. This can determine the applicability of a RTIL as a solvent for specific target solutes.

    f) Toxicology. SACHEM has agreed to facilitate testing for aquatic toxicity and human health affects for the classes of RTIL which have the most favorable characteristics for industrial use as solvents.

    g) Solute Partitioning and Solubility Studies: Linear Solvent Free Energy Relationships (LFER). It is our intention to partition a sizeable solute set in each synthesized ionic liquid and generate a corresponding LFER to describe the partition.

Expected Results:

The development of RTIL as alternative industrial solvents will lead to new sustainable technologies, especially involving extraction, which will help to alleviate the health, safety, and environmental concerns arising from the pervasive use of VOCs. Development of fundamental, molecular-based, descriptions and models of these systems, will greatly aid their application and provide a firm underpinning for further development. Thus, the long term impact of the proposed research is both fundamental, providing an understanding of a fascinating new field, and of economic and societal benefit.

Publications and Presentations:

Publications have been submitted on this project: View all 28 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 17 journal articles for this project

Supplemental Keywords:

Chemical transport; alternative media; chemicals, toxics, green chemistry, alternatives, sustainable development, clean technologies, environmentally conscious, RFA, Scientific Discipline, Sustainable Industry/Business, cleaner production/pollution prevention, Environmental Chemistry, Sustainable Environment, Technology for Sustainable Environment, New/Innovative technologies, Environmental Engineering, linear solvent free energy relationships, solvent substitutes, cleaner production, physicochemical data, room temperature ionic liquids, environmentally benign solvents, green process systems, industrial process, toxicity, innovative technology, ionic liquids, industrial innovations, industrial separators, source reduction, Volatile Organic Compounds (VOCs), pollution prevention, green chemistry

Progress and Final Reports:

Final Report