Effects of Co-Constituents on the Fate and Transport of Emerging Contaminants in Porous Media

Liao, Shuchi

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Overview

Year:: 2021
Contributor:: Liao, Shuchi (creator); Hurt, Robert (Reader); Shukla, Anita (Reader); Pennell, Kurt (Advisor); Brown University. Engineering: Fluid, Thermal, and Chemical Processes (sponsor)
Genre:: theses
Subject:: Nanoparticles; Environmental engineering; Contaminant transport; Perfluorinated chemicals; Porous materials
Extent:: xxii, 219 p.

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Abstract:: Contaminants are commonly found to co-exist with other chemical constituents in the subsurface. These co-constituents can have significant impacts on the properties of both the contaminants of interest and the porous medium, and thus affect the fate and transport of contaminants in the environment. To accurately assess contaminant risk and control the exposure, an extensive understanding of the influence of co-constitutes on the transport, retention and reaction of contaminants is required. The overall goal of this research is to investigate the impact of co-constituents on the fate and transport of two contaminants of emerging concerns (i.e. engineered nanoparticles and per and polyfluoroalkyl substances, PFAS) in porous media. The specific objectives of the research focus on 1) the effects of rhamnolipid biosurfactant on engineered nanoparticles (iron oxide nanoparticles and silver nanoparticles) transport and reactivity in water-saturated porous media; (2) the impact of Aqueous Film Forming Foam (AFFF) on Non-Aqueous Phase Liquid (NAPL) solubility and mobilization, and (3) the influence of residual NAPL on PFAS transport and retention in porous media. A combination of batch, column and mathematical modeling studies were performed to evaluate the transport and reactivity of the contaminants in the presence of co-constituents, and to reveal the underlying mechanisms governing the fate of these emerging contaminants in the environment. For iron oxide nanoparticles (IONP), the presence of rhamnolipid (10 mg L-1 or 50 mg L-1) resulted in ~25 % and ~50 % more breakthrough of the injected IONP mass, while preflushing the porous medium with 50 mg L-1 rhamnolipid further increased IONP mass breakthrough by ~30 %. A mathematical model that incorporated nanoparticle filter ripening and biosurfactant competitive adsorption successfully reproduced experimental observations. For silver nanoparticles (nAg), co-injection of nAg with rhamnolipid (2, 5 and 50 mg L-1) reduced nAg dissolution and decreased Ag+ breakthrough by ~22% under acidic conditions, and increased nAg breakthrough by more than 25% at neutral pH. These observed changes in nanoparticle stability and mobility were attributed to rhamnolipid adsorption on nanoparticle and porous media surfaces, which markedly altered nanoparticle surface activity and blocked porous media attachment sites. In Addition to engineered nanoparticles, interactions between NAPL and PFAS in co-contaminated source zone were also investigated. Although the presence of AFFF had negligible effect on NAPL solubility, AFFF can effectively reduce NAPL-water interfacial tensions to less than 3 mN/m, which resulted in partial NAPL mobilization in unconsolidated sands. In addition, the presence of residual NAPL can provide additional retention via NAPL-water interfacial adsorption, which delayed PFAS breakthrough by 0.1 to 1 pore volume (PV) under the experimental conditions investigated. Taken in concert, interactions of PFAS with NAPL can alter their distributions and transport behaviors in the subsurface.
Notes:: Thesis (Ph. D.)--Brown University, 2021

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Citation

Liao, Shuchi, "Effects of Co-Constituents on the Fate and Transport of Emerging Contaminants in Porous Media" (2021). Fluid, Thermal, and Chemical Processes Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:ug5yt44p/

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Fluid, Thermal, and Chemical Processes Theses and Dissertations

Theses and Dissertations for the Fluid, Thermal, and Chemical Processes department.
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