Emulsions to Trap and Treat HC/OS for Subsurface Remediation

Morwick G360 PROJECT TEAM: Dr. Erica Pensini & Kristine Lamont (Undergraduate Research Assistant)

There are over 10,000 sites in Canada contaminated by toxic substances, most of which are hydrocarbons, organic solvents and heavy metals (e.g. hexavalent chromium). The success and safety of the subsurface remediation of pollutants relies on: 1) effective contact between the reactive species and pollutants, and 2) adequate containment of the pollutants (trapping) during the remedial treatment.

The Pensini lab previously developed a method that has the potential of trapping and treating hexavalent chromium in-situ. Existing technologies cannot simultaneously trap and treat HC/OS, hence allowing their uncontrolled migration in the subsurface. In response to this gap, the Pensini lab is developing a technology to trap and treat HC/OS in the subsurface. To this end, multiple emulsions of water in oil are used for the targeted delivery of reagents to HC/OS polluted areas. Multiple emulsions are obtained by first emulsifying reagents dissolved in water into oil, and subsequently emulsifying the oil into a low viscosity (i.e. pumpable) fluid containing water and natural polymers. Upon contacting organic solvents or hydrocarbons, the multiple emulsions become unstable (i.e. the water and the oil separate) and release the reagents. A group of reagents investigated are crosslinkers, i.e. species that connect polymer chains to one another to form an elastic network (gel).

The Pensini lab studied the crosslinker effectiveness in gelating natural polymeric carrier fluids upon contact with HC/OS, creating a barrier around them (i.e. trapping them). Testing will continue to investigate the effectiveness of oxidizers and Fenton’s reagents (i.e. oxidizers mixed with iron compounds) in degrading HC/OS, following the targeted release of the reagents exclusively in pollutant proximity. The targeted delivery of reagents will ensure effective HC/OS degradation because the reagents will not be dispersed (i.e. lost) in the clean zones, hence making good contact with HC/OS.

Schematics of the trapping process.

Dr. Alejandro Marangoni, Food Science, University of Guelph

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