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• 1.0 INTRODUCTION <br /> Bench scale laboratory testing was performed to evaluate the ability of ozone (03) to <br /> destroy chemicals of concern (CDCs) in soil (MW-31 and MW-32) and groundwater <br /> 1 (MW-3) from the Unocal #5098 site to Stockton, California The COCs at this site were <br /> gasoline range total petroleum hydrocarbons (TPH-g), BTEX compounds (benzene, <br />' toluene, ethylbenzene, and xylenes), and MTBE <br /> Ozone is a strong oxidant that can destroy a wide range of organic compounds, including <br />' petroleum hydrocarbons and MTBE Compounds may be completely mineralized to <br /> carbon dioxide (CO2) and water (H2O), although intermediates may be seen if they react <br /> more slowly than the parent compound Potential intermediates of MTBE oxidation <br />' include t-butyl alcohol (TBA) and acetone Iron and other metal ions in soil and <br /> groundwater can increase the effectiveness of ozone by reacting with ozone to form <br /> hydroxyl radicals (Bower, K C and C M Miller "Filter Sand-Phosphate Buffer Effect <br />' on 2,4-Dinitrotoluene Ozonation," J Environ Eng February 2002, 131-136, and <br /> references therein ) Because the hydroxyl radical is an even stronger oxidant than ozone, <br /> its formation will reduce the likelihood of oxidation by-products <br /> Equations 1-4 show overall chemical reactions for conversion benzene (C61­16), toluene <br /> (CAH$), ethylbenzene (C8H10), xylenes (C81­1i0), and MTBE (C5HiflO) to CO2 and water <br />' The stoichiometric ozone requirements for the complete mineralization of each <br /> contaminant are given in Table 1 Chemical reactions cannot be written for TPH-g and <br /> stoichiometric requirements cannot be pre-determined because TPH-g is a mixture of <br /> chemicals In practice, a greater-than-stoichiometric dose of 03 will usually be required <br /> because 03 is a non-selective oxidant that will react with natural organic matter and other <br /> non-target compounds, and because mass transfer of 03 into the aqueous phase and/or <br /> COCl into the gas phase is inefficient <br /> 1503 + C6H6 6CO2 + 1502 + 3H2O Eqn 1 <br /> benzene <br /> 1803 + C2H8 7CO2 + 1802 + 4H2O Eqn 2 <br /> toluene <br /> 2103 + C8HEo a 8CO2+ 2102 + 5H2O Eqn 3 <br /> ethylbenzene or <br /> xylene <br /> 1503 + C511120 -+ 5CO2 + 1502 + 6H2O Eqn 4 <br /> MTBE <br /> Table 1. Ozone Stoichiornetry <br /> Compound g Ozone/ g contaminant <br /> Benzene 9 2 <br /> Toluene 9 5 <br /> Ethylbenzene 9 5 <br /> Xylenes 9 5 <br />` MTBE 8 2 <br /> PRIMA Environmental 1 Eval of Ozone <br /> January 27 2005 ENSR-Unocal 5098 <br />