Development and Characterization of Controlled-Release Permanganate Gelfor Groundwater Remediation
This study focused on furthering the development of a novel, cost-effective scheme to remediate large, dilute plumes of DNAPLs in groundwater through the in-situ, well-based emplacement of concentrated permanganate solution mixed with a gelling agent. The controlled-release permanganate gel (CRP-G) solution was developed so that it may be injected and flow with groundwater and subsequently increase in viscosity over time to remain emplaced and slowly release MnO4- in a long-term, controlled release fashion. This study characterized CRP-G gelation and release mechanisms of MnO4- in saturated porous media through the execution of batch experiments, viscosity tests, and column tests. Specific attention was devoted to use of colloidal silica within the CRP-G. Results of batch tests indicated that gelation times can be modified on the order of 5 min to over 10 dys; dilution by flowing water in the subsurface will be a consideration upon gel engineering. Results of column tests in open water indicated that release of MnO4- from CRP-G occurred within 24 hrs. In column tests conducted with saturated, sandy media, gelation occurred within 1, 3, and 6 hrs when using CRP-G solution 25.0, 23.0, and 22.9 g/L of KMnO4. Permanganate mass flux approached values that are near the benchmark for this study (˜ 850 µg/day), with release lasting up to 3 dys. This release was characterized as rapid short-term release followed by a longer, stabilized release phase. Impact of dilution of the injected CRP-G solution in the subsurface will be a consideration upon gel formation.The use of colloidal silica as a controlled-release material for the CRP-G is promising. Further studies are warranted for the development of a novel remediation scheme using the CRP-G.
Environmental Engineering, Environmental Geology, Environmental Studies, Controlled release permanganate, controlled release sol gel, dilute plumes of DNAPLs, in situ chemical oxidation
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