Degradation of 2,4,6-trinitrotoluene in water and soil slurry utilizing a calcium peroxide compound

The degradation of 2,4,6-trinitrstoluene was examined in pure water and contaminated soil slurry using calcium peroxide as a source of solid hydrogen peroxide and oxygen. The extent of TNT oxidation was compared with that obtained by using hydrated lime, which is normally generated by slurrying CaO(2) in water and contained in CaO(2) technical formulation (similar to 50%, w/w). Complete TNT degradation occurred between 280 min, 0.1% CaO(2)/Ca(OH)(2) and 20 min. 1% CaO(2)/Ca(OH)(2). A large part of the generated oxidation products, 80-90%, were adsorbed on the solid calcium hydroxide, whereas the remaining 10-20% was detected in solution until 48 h. Removal of nitro groups was extremely effective in CaO(2) slurry, where all the nitrogen (3 mol per mol of TNT) was removed from TNT within 240 min. Respect to calcium hydroxide, the peroxy compound liberated H(2)O(2) in solution, 370 mg l(-1) at 0.2% CaO(2), w/v, which then decomposed within 480 min. Most of the (14)C-TNT was retained more strongly on the calcium hydroxide generated by slurrying CaO(2). This pool remained adsorbed on the solid until pH dropped below 5.8. The treatment of a contaminated soil slurry, 700 mg TNT kg(-1), reduced CH(3)CN extractable TNT below 20 mg kg(-1) at very low concentration of CaO(2)/Ca(OH)(2), similar to 0.2% w/w. Both oxidants do not lead to soil sterilization as the phosphorus added to neutralize the pH serves as a source of nutrient for the soil biomass. (C) 1999 Elsevier Science Ltd. All rights reserved.