Emulsion-Based Delivery of Alkalinity for Subsurface pH Control
Emulsions are widely utilized to encapsulate, deliver, and release active ingredients
and are routinely used in environmental applications. Alkalinity-releasing particles can
be encapsulated within emulsions to provide long term pH control as alkalinity slowly
releases from the oil droplets retained in the subsurface. Through a combination of
laboratory experiments and mathematical ... read moremodeling, this work addresses: (i) emulsion
transport and retention in porous media; (ii) alkalinity release from particles
encapsulated in emulsion oil droplets; and (iii) the ability of emulsions to provide
passive, yet sustained, pH treatment. Concentrated emulsion transport and deposition
behavior was predicted from particle transport models adapted and parameterized using
data from transport of dilute emulsion. Dispersivity was found to increase with
decreasing water saturation (i.e., from mass retention) in emulsion systems, but also
more broadly in partially saturated air-water and NAPL-water systems as a whole.
Encapsulation of alkalinity-releasing particles within the emulsion oil droplets was
able to control the rate of alkalinity release through the increased resistance to mass
transfer via the oil-water interface (orders of magnitude reduction in rates of
release). Results illustrate how emulsions containing only limited loadings of MgO and
CaCO3 particle are able to provide long-term pH treatment in columns containing sandy
porous media. Models developed and employed herein provide a tool that may aid in
designing treatments employing oil-in-water emulsions, as well as providing insight into
how to best reach or maintain site specific pH
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Civil Engineering.
Advisor: C. Andrew Ramsburg.
Committee: Steven Chapra, Robert Viseca, Hyunmin Yi, and Brent Sleep.
Keyword: Environmental engineering.read less