Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions

摘要

1,2,3-trichloropropane (TCP) is a contaminant of DOD concern mainly due to it use in solvent formulations for paint and varnish removal, cleaning and degreasing, etc. Compared with other chlorinated solvents, TCP is similarly mobile, exceptionally persistent, and relatively toxic, suggesting that TCP will pose clean-up challenges that are similar, but in some respects more difficult. While TCP is characteristically recalcitrant, to both abiotic (and biotic) degradation pathways, potentially beneficial transformations of TCP are possible by hydrolysis, elimination, reduction, and oxidation. The goal of this project was to provide a detailed, quantitative characterization of these pathways of TCP degradation in water or soil. Hydrolysis of TCP under ambient conditions of pH and temperature is negligible, but base-catalyzed hydrolysis becomes favorable at high pH and temperature, such as under conditions of in situ thermal remediation (ISTR). Oxidation of TCP is less favorable than it is with many contaminants and is negligible with mild/specific oxidants like permanganate. However, the stronger oxidants involved in some in situ chemical oxidation (ISCO) processes-esp. hydroxyl and sulfate radicals-do oxidize TCP. Reduction of TCP under the mild conditions involved in natural attenuation is negligible, and the treatments used in conventional forms of in situ chemical reduction (ISCR)- such as granular zero-valent iron (ZVI)-give only slow dechlorination. More rapid degradation of TCP was obtained by reduction with nano ZVI, palladized nano ZVI, and zero-valent zinc (ZVZ). The potential for remediation of TCP with ZVZ was investigated in batch and column experiments because this combination might prove to be a novel solution to a distinctive problem.