Degradation and Extraction of Organochlorine Pollutants from Environmental Solids under Subcritical Water Conditions

Abstract

A subcritical water degradation and extraction method was developed to remediate environmental soils contaminated by highly recalcitrant organochlorine pollutants. Hydrogen peroxide was used to effectively decompose organochlorine pollutants under subcritical water conditions. As a method optimization study, the static wet oxidation of chlorophenols was first performed in subcritical water with and without added hydrogen peroxide. Complete oxidation was achieved using an added oxidant, and thus, the oxidation and extraction of chlorophenols from a sand matrix was then attempted. Complete oxidation and extraction with added oxidant were achieved within 30 min at 100 °C. We then investigated the subcritical water degradation and extraction of dieldrin, mirex, and p,p′-DDD. These organochlorine pesticides were not as easily oxidized as the chlorophenols, and the benefit of adding hydrogen peroxide was only clearly observed at 200 °C. Approximately a 20% increase in degradation was noted for each pesticide and insecticide at this temperature. Unfortunately, this difference was not observed with an increase in temperature to 250 °C, except in some cases, where the amount of degradation byproducts was reduced. Dieldrin and p,p′-DDD were essentially destroyed at 250 °C, while all the pesticides and the insecticides were completely removed from the sand at this temperature. The proposed method was then used to remediate a soil sample highly contaminated with DDT. The soil was obtained from the grounds of an old DDT mixing facility in Virginia and has been aging for several decades. Not only was 100% removal of DDT from this soil achieved using the proposed method at 250 °C, but also, the extracted DDT was completely destroyed during the process. The proposed remediation method, therefore, demonstrates a high potential as an efficient and environmentally sound technique for the detoxification of soils.

Decomposition of Organic Pollutants in Subcritical Water under Moderate Conditions

“…CLO degradation in water was tested through applying UV irradiation in combination with a TiO 2 catalyst at pH 10.3; HPLC analysis revealed the formation of numerous organic intermediates and ionic products [20]. Even though some organochlorine pesticides, such as dieldrin, mirex, and p,p ′ -DDD were successfully degraded in subcritical water with the addition of hydroxy-peroxide [21], no reports were found for CLO.…”

Screening, characterization and optimization of potential dichlorodiphenyl trichloroethane (DDT) degrading fungi

“…The production of CBP indicates a reductive dechlorination; this could be an intermediary impact of the DBP-to-BP conversion. After that, ring-cleavage processes totally degrade the BP [ 56 , 57 , 58 ,and6]]. Pichia kluyveri FM012, Rhizopus arrhizus, Trichoderma hamatum, Pleurotus ostreatus, Fomitopsis pinicola, Pleurotus eryngii, Penicillium, Phlebia, Paecilomyces, Trichoderma, Allescheriella, Alternaria, Microsporum, Aspergillus, etc.…”