Understanding the Role of Metal Solubility in Controlled Release of Alkalinity from Particle-Containing, Oil-in-Water Emulsions.
Leach, Olivia Isabel Morris.
- Remediation of contaminants in the subsurface is a key environmental issue. Due to its noninvasive and cost-effective approach, an increasingly common method of subsurface cleanup is bioremediation, in which naturally-occurring microbes are stimulated to transform contaminants into benign or immobile substances. In order to create a favorable environment for these microbes, there are many factors ... read morethat must be carefully controlled; these include sources of carbon, energy and nutrient availability, temperature, and pH. In situ bioremediation requires that these conditions be manipulated within the subsurface. Traditional subsurface alkalinity control methods are hindered by limited mixing and dispersion in the subsurface. Oil-in-water emulsions have potential as an in situ alkalinity release and delivery system; however the mechanisms that control this alkalinity release are not well documented. The goal of this project was to examine how the chemistry of oil-in-water emulsions can be manipulated in order to control alkalinity release in the subsurface. The key hypothesis was that increasing oil polarity will increase the solubility of particles in oil, and thereby increase the thermodynamic force of partitioning into the aqueous phase. Experimental methods were divided into three main objectives: stability, alkalinity release, and solubility experiments. A spectrophotometer was used to assess the stability of MgO and CaCO3 particles in oil. Batch experiments were used to assess both the solubility of these particles in oil and the alkalinity release rate of these particles as a function of oil polarity. Data suggests that both MgO and CaCO3 particles display sufficient stability in soybean oil for encapsulation within emulsions, and that increasing the oil polarity increases the rate of alkalinity release into the aqueous phase. Results also indicate some evidence of particle solubility increasing as a function of oil polarity; however, these solubility experiments require refinement.read less