Comparative study on oxidative treatments of NAPL containing chlorinated ethanes and ethenes using hydrogen peroxide and persulfate in soils.
The goal of this study was to assess the oxidation of NAPL in soil, 30% of which were composed of chlorinated ethanes and ethenes, using catalyzed hydrogen peroxide (CHP), activated persulfate (AP), and H(2)O(2)-persulfate (HP) co-amendment systems. Citrate, a buffer and iron ligand, was amended to the treatment system to enhance oxidative treatment. Four activation/catalysis methods were employed: (1) oxidant only, (2) oxidant-citrate, (3) oxidant-iron(II), and (4) oxidant-citrate-iron(II). The NAPL treatment effectiveness was the greatest in the CHP reactions, the second in HP, and the third in AP. The effective activation and catalysis methods depended on the oxidant types; oxidant only for CHP and HP and oxidant-citrate-iron for AP. The treatability trend of chlorinated ethanes and ethenes in the soil mixture was as follows: trichloroethene > tetrachloroethene > dichloroethane > trichloroethane > tetrachloroethane. A significant fraction of persulfate remained in the oxidation systems after the 2-day reaction period, especially in the citrate-iron(II) AP. In general, oxidation systems that included citrate maintained a post-treatment pH in the range of 7-9. A final pH of AP oxidation systems was acidic (pH 2-3), where a molar ratio of citrate-iron(II) was less than 1.8 and where no citrate was amended.
National Research Council, R. S. Kerr Environmental Research Center, P. O. Box 1198, Ada, OK 74821, USA. ko.saebom@epa.gov
Saebom
S
Ko
Michelle
M
Crimi
Bruce K
BK
Marvin
Victor
V
Holmes
Scott G
SG
Huling
D019343:Citric Acid / Q000737:chemistry; D052918:Environmental Restoration and Remediation; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D017670:Sodium Compounds / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*
D006843:Hydrocarbons, Chlorinated; D017670:Sodium Compounds; D012989:Soil Pollutants; D013431:Sulfates; D019343:Citric Acid; D006861:Hydrogen Peroxide; C024625:sodium persulfate