Offer Description
The Pensini lab is seeking PhD students with a background in chemistry, physical chemistry, physics or closely related disciplines to conduct experimental (lab-based) research on the mixing behaviour, abiotic reactions and migration of toxic solvents in groundwater, in the presence of naturally occurring ions. Students graduating in this area often find employment in environmental consulting firms.
Students involved in these projects will have the opportunity to work at synchrotrons in Canada, the UK and at the Institut Laue Langevin (Grenoble), in close collaboration with a hands-on advisor.
DETAILS:
The Pensini lab has been investigating the mixing behavior of miscible solvents in water in the presence ions naturally present in groundwater and amphiphiles (soaps). Toxic miscible solvents such as sulfolane, tetrahydrofuran and acetonitrile are used in industrial processes and are found in aquifers due to improper handling or accidental spills. We work in collaboration with industry partners, to help them clean water and understand pollutant migration in impacted aquifers. Graduate students previously working in this area have found employment in environmental consulting firms, including those directly involved in our projects.
Our goal has been to remove them from water and to understand their unwanted migration in impacted aquifers. Mixing between miscible solvents and water occurs due to hydrogen (H) bonding. We found that amphiphilic molecules can hamper H bonding between solvents and water, causing solvent-water separation, to clean up water.
We are currently expanding this research, using foams to extract miscible pollutants. This study has started at the University of Guelph and will involve experiments at the UK synchrotron Diamond this coming summer.
We are also expanding this research to understand the mixing behaviour of miscible pollutants in water, in the presence of ions naturally occurring in water. For example, we found that sulfate ions abundant in impacted sites separate sulfolane from water and cause it to partition in co-contaminants (such as hydrocarbons). This has important implications on sulfolane migration in groundwater. We are also studying how ions impact sorption of pollutants onto mineral surfaces. When ions separate miscible solvents from water, sorption can be promoted (delaying pollutant migration) or hindered (facilitating pollutant migration), depending on the minerals in impacted aquifers. The study which started with sulfolane will be extended to other solvents.
We have been analyzing separation processes by probing molecular interactions between the components of ternary mixtures containing water, miscible solvents and ions (e.g., using FTIR). We have also been studying the formation of molecular solvent clusters and the structure of water in the presence of solvent traces and salts, using synchrotron small angle X ray scattering and small angle neutron scattering, as well as fluorescence spectroscopy. Sorption of solvents onto surfaces has been investigated through bulk tests as well as using synchrotron X-ray absorption fine structure (XAFS). Students involved in the proposed research will be trained to become well-versed in these techniques.
Complementary to this research, we are analyzing abiotic transformation processes of pollutants in the environment. As an example, we are finding that amino acids generated by bacterial processes can be involved in redox reactions with sulfolane, in the presence of ferrous ions. This study is motivated by the conditions identified in an impacted site we are helping characterize and remediate.
Where to apply
E-mail: epensini@uoguelph.ca
