ACTIVATED PERSULFATE AND CATALYZED HYDROGEN PEROXIDE PROPAGATION SYSTEM REACTIVITY AND STABILITY DURING IN SITU CHEMICAL OXIDATION

Thesis (Ph.D.), Department of Civil and Environmental Engineering, Washington State UniversityThe types of activators and kinetics for persulfate activation are still being researched, as well as stabilization methods to prolong CHP reactions. The objective of this research was to investigate the activation of persulfate by surfactants, study persulfate activation during exertion of total oxidant demand (TOD), and compare CHP stabilization by phosphate, phytate, and citrate. The first chapter presents an introduction to the theory and purpose of the research. The second chapter examines activation of persulfate at acidic and basic pH by anionic, nonionic, and cationic surfactants, and the reactive oxygen species generated by persulfate in the presence the surfactants. The results of this research demonstrate that surfactants added to ISCO systems often activate persulfate to generate reductants at both acidic and basic pH, and hydroxyl radical at basic pH. These findings provide a new paradigm for persulfate activation in SISCO systems; pH regimes >11 may not be necessary for persulfate activation resulting in cost savings and potentially more effective activation of persulfate.The third chapter investigates the generation of reactive oxygen species and the destruction of a common groundwater contaminant, trichloroethylene (TCE), during TOD exertion in low (0.5%), medium (1.3%), and high (2.4%) SOM soils. The results from this research demonstrate that persulfate activation occurred as TOD was exerted. The activation was specific to the generation of reductants + nucleophiles, but not hydroxyl radical. In addition, TCE degradation occurred in proportion to the TOD exerted. The findings of this research document that, unlike permanganate TOD, the TOD exerted during persulfate ISCO applications can activate persulfate to generate reductants + nucleophiles that can potentially degrade contaminants during persulfate ISCO applications.The forth chapter explores the use of lower concentrations of stabilizers in catalyzed hydrogen peroxide propagations and their effect on hydrogen peroxide decomposition and the reactive oxygen species generated. The findings of this research demonstrate that lower concentrations of effective stabilizers such as phytate and phosphate can increase hydrogen peroxide longevity in CHP ISCO while maintaining the generation of reactive oxygen species, thus reducing overall treatment costs and providing more effective process conditions.Department of Civil and Environmental Engineering, Washington State Universit