Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2003
Publication Date: 8/1/2003
Citation: Anthony C. Pierpoint, Cathleen J. Hapeman, and Alba Torrents Ozone treatment of soil contaminated with aniline, trifluralin and other contaminants Submitted to Chemosphere Accepted by Journal: 4/27/2003 Published: 50(8):1025-1034 Interpretive Summary: Soils that are highly contaminated with organic compounds are frequently difficult to remediate. In-situ treatment using indigenous soil microorganisms is often preferred, but frequently these compounds are resistant to biological degradation. In these cases, pretreatment with an oxidizing agent would be desirable. Studies were conducted to determine the ability of ozone to degrade trifluralin (a common herbicide) and aniline, a pesticide precursor, in soil. Ozone was pumped through moist soil columns and rapid degradation of aniline was observed. Although slower, similar results were found with trifluralin. Degradation products were identified. Overall results suggest that ozonated water may improve contaminant removal for low solubility. This information will be useful in designing remediation strategies for higly contaminated soils.
Technical Abstract: Column studies were conducted to determine the ability of ozone to degrade aniline and trifluralin in soil. Ozone (O3) rapidly degraded aniline from soil under moist soil conditions, 5% (wt). Removal of 77-98% of [14C]-aniline was observed from soil columns (15 mL, I.D. = 2.5 cm), exposed to 0.6% O3 (wt) at 200 mL/min after 4 min. Initial ozonation products included nitrosobenzene and nitrobenzene, while further oxidation led to carbona dioxide (CO2). Ring labeled [14C] trifluralin removal rates were slower, requiring 30 min to achieve removals of 70-97%. Oxidation and cleavage of the N-propyl groups of trifluralin was observed, with the formation of 2,6-dinitro-4-(trifluoromethyl) aniline, 2,6-dinitro-N-propyl-4-(trifluoromethyl) benzamine, and 2,6-dinitro-N-propyl-N-acetonyl-4-(trifluoromethyl) benzamine. Base solutions revealed that trifluralin was similarly oxidized to CO2, where 72-83% of the activity recovered comprised 14CO2. Use of ozone-rich water improved contaminant removal in trifluralin-treated soil columns, but did not improve removal in aniline, pentachloroaniline, hexachlorobenzene treated soil columns, suggesting that ozonated water may improve contaminant removal for reactive contaminants of low solubility.