Thesis
Base-activated persulfate treatment of contaminated soils with pH drift from alkaline to circumneutral
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/100683
Abstract
Recent empirical evidence suggests that base-activated persulfate must be conducted at pH > 10 to be effective. However, other data suggests that persulfate reactivity remains as the pH drifts below pH 10. The potential for persulfate activation after base addition as the pH drifts from alkaline to circumneutral was investigated in four soil systems of varying soil organic matter (SOM) contents. Two probe compounds, nitrobenzene and hexachloroethane, were used to quantify the relative reactivity of hydroxyl radical and reductants, respectively. Hydroxyl radical activity was greatest in persulfate-soil slurries at pH 12 with decreasing hydroxyl radical activity in the systems in which the pH had drifted to pH 10 and pH 8. Furthermore, greater rates of hydroxyl radical generation were found with decreasing SOM contents, which is likely due to a lower degree of hydroxyl scavenging by SOM. Superoxide radical and reductant generation also occurred at all pH systems with lower rates as the pH drifted toward circumneutral. In all pH systems, hexachloroethane degradation was greatest in soil systems with greater SOM content. Considerably less reductant formation occurred for the systems at pH 10 and pH 8 once the SOM was removed, but reductants were still formed. Persulfate decomposition and pH drift were also monitored in conjunction with hydroxyl radical and reductant experiments. Persulfate decomposition occurred most rapidly in the soil slurries with greater SOM. Persulfate decomposition was minimal in all other slurries with the least decomposition occurring once SOM was removed. pH drift was approximately parallel to persulfate decomposition in all four soil systems with the most rapid decline in the higher SOM soil systems. The results of this research demonstrate that base-activated persulfate may be more active than previously thought as the pH drifts towards neutral. From a practical treatment perspective, application of base-activated persulfate in situ may potentially extend treatment longer than previously thought making it a more efficient ISCO technology.
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Details
- Title
- Base-activated persulfate treatment of contaminated soils with pH drift from alkaline to circumneutral
- Creators
- Michael Andrew Miraglio
- Contributors
- Richard J. Watts (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900524802601842
- Language
- English
- Resource Type
- Thesis