title: Thermally activated peroxydisulfate in the presence of additives: a clean method for the degradation of pollutants.
abstract: The kinetics and mechanism of the thermal activation of peroxydisulfate, in the temperature range from 60 to 80 degrees C, was investigated in the presence and absence of sodium formate as an additive to turn the oxidizing capacity of the reaction mixture into a reductive one. Trichloroacetic acid, TCA, whose degradation by a reductive mechanism is well reported in the literature, was used as a probe. The chemistry of thermally activated peroxydisulfate is described by a reaction scheme involving free radical generation. The proposed mechanism is evaluated by a computer simulation of the concentration profiles obtained under different experimental conditions. In the presence of formate, SO(4)(-) radicals yield CO(2)(-), which are the main species available for degrading TCA. Under the latter conditions, TCA is more efficiently depleted than in the absence of formate, but otherwise identical conditions of temperature and [S(2)O(8)(2-)]. We therefore conclude that activated peroxydisulfate in the presence of formate as an additive is a convenient method for the mineralization of substrates that are refractory to oxidation, such as perchlorinated hydrocarbons and TCA. This method has the advantage that leaves no toxic residues.
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET. C.C. 16, Suc. 4, (1900) La Plata, Argentina.
authors.forename: Verónica C
authors.initials: VC
authors.lastname: Mora
authors.forename: Janina A
authors.initials: JA
authors.lastname: Rosso
authors.forename: Galo
authors.initials: G
authors.lastname: Carrillo Le Roux
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Mártire
authors.forename: Mónica C
authors.initials: MC
authors.lastname: Gonzalez
mesh_terms: D052918:Environmental Restoration and Remediation / Q000379:methods*; D005561:Formates / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D017670:Sodium Compounds / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D013696:Temperature; D014238:Trichloroacetic Acid / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D005561:Formates; D005609:Free Radicals; D017670:Sodium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; C030544:formic acid; D014238:Trichloroacetic Acid; C024625:sodium persulfate