Erica Pensini, PhD, P.Eng (Associate Professor)

Research Interests

My current research focuses on three key areas: 1) piezoelectric gels for clean energy production; 2) new energy-efficient water treatment technologies, that enable water reuse and restoration of polluted aquifers; 3) water-miscible pollutant migration in impacted aquifers.

Courses

• ENGG2560 Environmental Engineering Systems

• ENGG6260 Colloids, Interfaces and Emulsions: Concepts and Practical Applications

• ENGG4240 Site Remediation

Research Projects

Piezoelectric gels for clean energy production

Piezoelectric materials generate electrical energy when mechanical energy is applied to them. Energy conversion occurs because the piezoelectric molecular structure is oriented. As a result, it exhibits an electric dipole (i.e., a local charge separation). When mechanical energy is exerted on the material, the electrical dipole is deformed and electrical charges separate.

The Pensini lab is developing hydrogels with high water content (90wt%) to produce clean energy. Such gels would be well-suited to produce piezoelectric floors and piezoelectric furniture, such as waterbed mattresses and pillows, as well as weighted blankets (used to reduce anxiety while sleeping). These floor and furniture would allow producing clean energy in a delocalized fashion, to help achieve net zero energy buildings.

Our aim is to improve on our first generation of hydrogels, in which conductive molecular clusters are structured by self-assembled amphiphiles. To this end, we are investigating the correlation between the characteristics of self-assembled structures and gel performance, i.e., current produced upon compression and current decay during mechanical relaxation.

In this research, we use a combination of techniques to probe molecular interactions and self-assembly, including Fourier Transform Infrared Spectroscopy and X-Ray Scattering. Rheology is used to probe the mechanical properties of the gels. Cyclic voltammetry is one of the approaches used to test the ferroelectric behaviour of the gels. This research is conducted with equipment available at the University of Guelph as well as the Canadian synchrotron (Canadian Light Source, Saskatoon).

Separation of Miscible Pollutants from Water

The Pensini lab separates water from water-miscible solvents with amphiphiles that compete with the solvents for hydrogen (H) bonds with water. Water is an ensemble of different water clusters, comprised of species that donate or accept one or more H-bonds. Water miscible solvents H-bond with different water species, with different strength. We recently discovered that species which compete with solvents for the same water species initiate water-solvent separation. These species include sugars and their alcohols, benign ions and selected amphiphiles (e.g., sodium lauroyl lactylate). We are currently focusing on amphiphiles because they simultaneously enable the removal of unwanted metal ions from water, as outlined in our recent publications.

Mixing behavior and migration of miscible solvents in groundwater

The Pensini lab has been investigating the mixing behavior of miscible solvents in water in the presence ions naturally present in groundwater and amphiphiles. 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.

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, 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 contributed by the dissolution of gypsum in some Canadian aquifers (in Alberta) 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).

Publications

Please visit my Google scholar profile (https://scholar.google.com/citations?user=NOWkqbsAAAAJ&hl=en&oi=ao)