title: Identification of Active Radical Species in Alkaline Persulfate Oxidation.
abstract: A proposed mechanism for alkaline activation of persulfate involves generation of sulfate (SO(4)(-)), hydroxyl (HO·), and superoxide radicals (O(2)(-)). The present study investigated the feasibility of chloroform (CF) degradation using alkaline activated persulfate and identified the active radical species using a radical inhibition technique. 2-propanol (PrOH) (preferentially reacted with HO·), phenol (preferentially reacted with both HO· and SO(4)(-)), and carbon tetrachloride (CT) (preferentially reacted with O(2)(-)) were used to inhibit the degradation of CF, and the extent of inhibited degradation was used to indicate the predominant radical species. Additions of PrOH and phenol appeared to significantly scavenge SO(4)(-) and HO· and resulted in inhibited CF degradation. Here, the authors demonstrated that SO(4)(-) and HO· were predominant radicals in the alkaline activated persulfate system. The presence of O(2)(-) scavengers (i.e., CT) resulted in a partial inhibition of CF degradation and, hence, one can speculate that O(2)(-) is a minor radical species.
authors.affiliation: Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung City 402, Taiwan.
authors.forename: Chenju
authors.initials: C
authors.lastname: Liang
authors.forename: Jung-Hsuan
authors.initials: JH
authors.lastname: Lei
mesh_terms: D002725:Chloroform / Q000737:chemistry; D016166:Free Radical Scavengers; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D017670:Sodium Compounds / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D016166:Free Radical Scavengers; D017670:Sodium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; D002725:Chloroform; C024625:sodium persulfate