Electron beam remediation of soils impacted with heavy hydrocarbons

Abstract

During electron beam (EBeam) irradiation, high-energy electrons can generate physical and chemical changes in a substance such as chain scission and cross-linking. Irradiation of soil is shown to be an effective technology for rapid reduction of Total Petroleum Hydrocarbons (TPH) in crude oil impacted soils. An experimental apparatus for batch treatment of 100 g soil samples was built and tested using a 10 MeV, 15 kW electron beam. The samples were a variety of crude oil impacted soil samples with TPH contents ranging between 1.6 and 32% by mass. Soils of initial TPH up to 9.1% (dry weight basis) TPH levels were reduced to below a target cleanup level of 1% with irradiation doses ranging from 700 kJ/kg to 1100 kJ/kg and treatment times less than 200 s, with maximum soil temperatures less than 450 °C. Soils with elevated moisture content required higher dosages or preliminary drying. EBeam treatments resulted in 1) reduction for both light and heavy hydrocarbon, 2) generation of new light hydrocarbons, and 3) generation of fixed carbon, indicating that the mechanisms of electron beam remediation include radical induced reactions at relatively low temperature and relatively short time scales and not simply thermal desorption effects.