title: Mechanism of base activation of persulfate.
abstract: Base is the most commonly used activator of persulfate for the treatment of contaminated groundwater by in situ chemical oxidation (ISCO). A mechanism for the base activation of persulfate is proposed involving the base-catalyzed hydrolysis of persulfate to hydroperoxide anion and sulfate followed by the reduction of another persulfate molecule by hydroperoxide. Reduction by hydroperoxide decomposes persulfate into sulfate radical and sulfate anion, and hydroperoxide is oxidized to superoxide. The base-catalyzed hydrolysis of persulfate was supported by kinetic analyses of persulfate decomposition at various base:persulfate molar ratios and an increased rate of persulfate decomposition in D(2)O vs H(2)O. Stoichiometric analyses confirmed that hydroperoxide reacts with persulfate in a 1:1 molar ratio. Addition of hydroperoxide to basic persulfate systems resulted in rapid decomposition of the hydroperoxide and persulfate and decomposition of the superoxide probe hexachloroethane. The presence of superoxide was confirmed with scavenging by Cu(II). Electron spin resonance spectroscopy confirmed the generation of sulfate radical, hydroxyl radical, and superoxide. The results of this research are consistent with the widespread reactivity reported for base-activated persulfate when it is used for ISCO.
authors: Department of Civil & Environmental Engineering, Washington State University, Pullman, Washington 99164-2910, USA.
authors: Olha S
authors: OS
authors: Furman
authors: Amy L
authors: AL
authors: Teel
authors: Richard J
authors: RJ
authors: Watts
mesh_terms: D000838:Anions / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D017666:Deuterium Oxide / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D017670:Sodium Compounds / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000838:Anions; D016166:Free Radical Scavengers; D017670:Sodium Compounds; D013431:Sulfates; D014867:Water; D013481:Superoxides; D012972:Sodium Hydroxide; D003300:Copper; D006861:Hydrogen Peroxide; C024625:sodium persulfate; D017666:Deuterium Oxide; D010100:Oxygen