title: Injectable silica-permanganate gel as a slow-release MnO4(-) source for groundwater remediation: rheological properties and release dynamics.
abstract: Injectable slow-release permanganate gels (ISRPGs), formed by mixing aqueous KMnO4 solution with fumed silica powders, may have potential applications in remediating chlorinated solvent plumes in groundwater. A series of batch, column, and two-dimensional (2-D) flow cell experiments has been completed to characterize the ISRPG and study the release of permanganate (MnO4(-)) under a variety of conditions. The experiments have provided information on ISRPG rheology, MnO4(-) release dynamics and distribution in porous media, and trichloroethene (TCE) destruction by the ISRPG-released oxidant. The gel possesses shear thinning characteristics, resulting in a relatively low viscosity during mixing, and facilitating subsurface injection and distribution. Batch tests clearly showed that MnO4(-) diffused out from the ISRPG into water. During this process, the gel did not dissolve or disperse into water, but rather maintained its initial shape. Column experiments demonstrated that MnO4(-) release from the ISRPG lasted considerably longer than that from an aqueous solution. In addition, due to the longer release duration, TCE destruction by ISRPG-released MnO4(-) was considerably more effective than that when MnO4(-) was delivered using aqueous solution injection. In the 2-D flow cell experiments, it was demonstrated that ISRPGs released a long-lasting, low-concentration MnO4(-) plume potentially sufficient for sustainable remediation in aquifers.
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China and State Key Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China.
authors.forename: S
authors.initials: S
authors.lastname: Yang
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA. lirong.zhong@pnnl.gov.
authors.forename: M
authors.initials: M
authors.lastname: Oostrom
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA. lirong.zhong@pnnl.gov.
authors.forename: M J
authors.initials: MJ
authors.lastname: Truex
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China and State Key Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China.
authors.forename: G
authors.initials: G
authors.lastname: Li
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA. lirong.zhong@pnnl.gov.
authors.forename: L
authors.initials: L
authors.lastname: Zhong
mesh_terms: D001673:Biodegradation, Environmental; D052918:Environmental Restoration and Remediation / Q000379:methods*; D060587:Groundwater / Q000737:chemistry*; D011196:Potassium Permanganate / Q000737:chemistry*; D012212:Rheology; D058428:Silica Gel / Q000737:chemistry*; D014241:Trichloroethylene / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; D011196:Potassium Permanganate; D014241:Trichloroethylene; D058428:Silica Gel