Development and characterization of colloidal silica-based slow-release permanganate gel (SRP-G): Laboratory investigations

作者：Lee Eung Seok^*; Gupta Neha

来源：Chemosphere, 2014, 109: 195-201.

DOI：10.1016/j.chemosphere.2014.01.020

• Groundwater
• Chlorinated ethylene
• KMnO4
• Slow-release system
• Gel
• Colloidal silica
• Remediation

Slow-release permanganate (MnO4-) gel (SRP-G) is a hyper-saline KMnO4 solution that can be used for treating large, dilute, or deep plumes of chlorinated solvents in groundwater. Ideally, the SRP-G injected into aquifers will slowly gelate to form MnO4-; gel in situ, and the gel will slowly releases MnO4-. Objectives of this study were to develop SRP-G using colloidal silica as gelling solution, characterize its gelation and release kinetics, and delineate its dynamics in a saturated sandy media. %26lt;br%26gt;The SRP-G exhibited a two-phase increase in viscosity: a lag phase characterized by little increase in viscosity followed by a short gelation phase. Gelation lag times of SRP-G solutions increased (from 0.5 h to 13 d) with decreasing KMnO4 concentrations (from 25 to 8 g L-1). Permanganate release from gelated SRP-G increased with increasing KMnO4 concentrations, and was characterized as asymptotic release with initial peak (0.9-2.2 mg min(-1)) followed by more attenuated release. Gelation lag times of SRP-G flowing in sands (linear velocity = 2.1 m d(-1)) increased (1, 3, and 6 h) with decreasing KMnO4 concentrations (25.0, 23.0, and 22.9 g L-1). Permanganate release from gelated SRP-Gs continued for up to 3 d and was characterized as asymptotic release with an initial peak release (similar to 1.2 g min(-1)) followed by more attenuated release over 70 h. Dilution of SRP-G by dispersion in porous media affects gelation and release kinetics. Increasing the silica concentration in the SRP-G may facilitate gelation and extend the duration of MnO4- release from emplaced SRP-G in porous media.

• 出版日期2014-8