Current Research

Research Themes

  • Physical chemistry of ions and organic solutes in very high temperature water.
  • Origins of Life / Prebiotic Chemistry: Amino acids and nucleic acids under deep-ocean hydrothermal vent conditions.
  • CANDU Nuclear reactor chemistry: the next generation of reactors.
  • Thermal power generation, carbon capture, and hydrogen co-generation.

 

Photo of lab equipment

 Summary of Research Interests

Many geological and industrial processes take place at conditions far beyond the range of conventional room temperature measurements.  The objective of research in the hydrothermal chemistry group is to develop the knowledge base and theoretical understanding needed to describe the behaviour of aqueous systems at extremes of temperature and pressure, and to apply these results to fundamental problems encountered in electrical power stations, nuclear reactors, geothermal ore bodies, deep-ocean hydrothermal vents, and carbon capture/sequestration.

Sensitive flow calorimeters, densitometers and AC conductance cells, constructed of inert materials to withstand the corrosive conditions, are used to determine the thermodynamic properties of simple electrolytes and organic molecules in liquid water at temperatures up to 400 deg C and pressures as high as 300 atm, to examine the effects of ionic charge and organic functional groups under conditions approaching the critical point of water. The form of the chemical species, and their equilibrium constants at high temperature and pressure, are being determined by conductance methods, and by UV-visible and Raman spectroscopy in flow systems with sapphire windows or in diamond anvil cells.  Spectroscopic, heat capacity and volumetric studies on metal complexes with ammonia, halides and chelating agents provide data and models to describe the temperature dependence of transition metal complexation and chelation equilibria.  Some of our MSc and PhD projects can be co-op or international exchange.

The novelty in the work lies in the very extreme conditions being studied, the potential for identifying unusual effects, and the need to develop specialised instrumental techniques to obtain quantitative data for multi-component aqueous systems under these very aggressive conditions.

 

Research Funding

The following companies and granting agencies have contributed to our research during the past five years: NSERC, Atomic Energy of Canada Ltd., Ontario Power Generation Ltd., The Electric Power Research Institute (EPRI), Inco, IAPWS, UNENE, Natural Resources Canada.

Logos of 9 funding agencies

 

 

Current Research Projects

(i) Solvation and Equilibria of Ions and Organic Solutes in Water up to Near-Critical Conditions: Weak acids and bases, and their salts, are useful solutes for probing high temperature solvation phenomena because they provide a direct means of examining the relative effects of ionic, and uncharged functional groups.  Papers A38 and A39 are among the first to report the profound competing effects of ionic charge and hydrophobic repulsion arising from critical locus effects in high temperature water, and include quantitative data for amines used by the electric power industry as important pH buffers in nuclear and thermal steam generators. We are extending this work to other amines, alkanolamines and organic acids, using high temperature densimetry, conductance, and UV-visible spectroscopic techniques to extend basic understanding of functional group additivity effects up to near-critical conditions. Papers A18, A19 and A21 reported data for thermally stable molecules with polar functional groups at temperatures above the range previously studied, and observed previously unreported solvent polarization effects. Paper A11 used these results and data from new measurements to derive a predictive model for partial molar volumes in high temperature water based on functional group additivity.

(ii) Origins of Life: Pre-Biotic Chemistry under Deep Ocean Hydrothermal Vent Conditions: The behaviour of amino acids under hydrothermal conditions is of interest to physical chemists seeking models to examine the hydration of zwitterions in high temperature water, and to geochemists investigating possible mechanisms for the origins of life in deep ocean hydrothermal vents.  We successfully determined Vo and C for a series of amino acids up to 250 deg C and showed that dipole solvation models describe their high temperature behaviour.  Together with Hakin’s VE(glycine) these are the first experimental values for any amino acids above 100 deg C.  They demonstrated that extrapolations of low-temperature data, widely used by geochemists to calculate peptide stabilities in deep ocean hydrothermal vents, diverge toward the wrong near-critical limit.  Ongoing work is using UV-visible spectrometry and thermally stable pH indicators to determine ionization constants and the thermal stability of amino acids and nucleic acid bases at temperatures up to 250 deg C  (Papers A1, A24, A30, and A39).

(iii) CANDU Nuclear Reactor Chemistry:  D2O Isotope Effects on Acid-base Ionization and Metal Hydrolysis: This project is for a definitive laboratory study to quantify D2O isotope effects on acid-base ionization and metal hydrolysis over the temperature range 100 to 300 deg C. The goals are to provide fundamental data and understanding for the difference in equilibrium constant of simple acids and bases between H2O and D2O, delta pK = {pK(D2O) – pK(H2O)}, at high temperatures and pressures; and  to provide a model for estimating the magnitude of D2O isotope effects on metal hydrolysis and metal oxide solubility.  Both objectives are relevant to the support and future development of CANDU heavy water reactors and will yield new insights into hydration in high temperature water. Our ongoing studies in this project use a one-of-a-kind hydrothermal AC conductance apparatus; hydrothermal UV-visible spectroscopic flow cells with thermally stable colorimetric pH indicators; Raman spectroscopy, and high-temperature standard partial molar volume measurements to determine the solvent isotope effects on equilibrium constants and standard partial molar volumes, delta pK and delta Vo (Papers A5, A10, and A16).

(iv) Generation IV Nuclear Reactor Chemistry: Ion Pairs and Complexes in Sub-critical and Supercritical Water (Joint Project between Canada and 10 Other Countries):  This project will use UV-visible spectroscopy, directly and in conjunction with thermally stable colorimetric pH indicators, Raman spectroscopy, and our new conductance instrument to determine ionization constants and ion association constants up to and above the critical point of water.  The conductance measurements yield transport properties and equilibrium constants for ion pairs up to 400 deg C from molality-dependent data.    Initial studies will be on ammonia, carbon dioxide, and metal chloride complexes.  UV-visible and Raman methods will be used to study complexes which cannot be studied by conductance due to the presence of high concentrations of other conducting species. The state-of-the-art conductance apparatus was constructed by R.H. Wood at the University of Delaware and is one of only two in North America with these capabilities.  This very fundamental research supports Canada’s emerging research program for the Generation IV supercritical water reactor and hydrogen co-generation technologies (Papers A2, A3, A4, A6, D2 and D4).

(v) Carbon Capture and Sequestration by Novel Phase-Separating Solvents (Joint Project with France including Student Exchange):  The chemical absorption of CO2 in mixed solvents is a promising technology for carbon dioxide (CO2) capture from post-combustion industrial effluents to reduce global warming. The regeneration of the solvent is costly, consuming 30 to 40% of the energy from the power station.  To reduce the energy cost, a novel concept has been proposed in which aqueous solutions of amines that phase separate at elevated temperatures would be used as the carbon-capture solvent. This project is a fundamental study of binary and ternary systems containing a series of structurally-related amines suitable for these “de-mixing” carbon capture processes.  The study will elucidate the structure-property relationships needed to design suitable de-mixing amines for CO2 absorption, by measuring the properties of a class of piperidine derivatives which undergo liquid-liquid phase separation and analyzing the effect of substitution by alkyl and/or aryl groups in different positions on the ring. The thermodynamic measurements will be performed mainly in the Laboratory for Thermodynamics and Molecular Interactions at Universite Blaise Pascal.  Raman spectroscopy at the Hydrothermal Chemistry Group of the University of Guelph will bring new information on the speciation of the absorbed carbon dioxide in amine solutions and in coexisting phases after de-mixing. Canadian and French industrial partners, Gas Liquid Engineering Ltd. and IFP Energies Nouvelles will provide guidance in the modelling and field applications of carbon capture technology.

 

last updated January 7th, 2013.