ABIOTIC REDUCTION OF 2,4-DINITROTOLUENE IN THE PRESENCE OF SULFIDE MINERALS UNDER ANOXIC CONDITIONS

Abiotic reduction of 2,4-dinitrotoluene (DNT) in the presence of sulfi de minerals has been investigated under anoxic conditions at 35 degree s C. 2,4-DNT was abiotically reduced to 4-amino-2-nitrotoluene (4-A-2- NT) and 2-amino-4-nitrotoluene (2-A-4-NT) in the presence of high conc entration of sulfide (0.84 mM). No abiotic reduction of 2,4-DNT was ob served in the presence of low sulfide concentration (0.42 mM). The rat e and the extent of the abiotic reduction of 2,4-DNT were increased wi th an increase in sulfide concentration. Sulfide served as an electron donor for the reduction of 2,4-DNT. The 2-nitro group was preferentia lly reduced, making the 2-A-4-NT:4-A-2-NT ratio in the final products 2:1. The addition of iron, nickel, and cobalt minerals significantly e nhanced the abiotic reduction. The FeS, NiS, and CoS solids formed in the serum bottles catalyzed the reduction of 2,4-DNT preferentially to 4-A-2-NT. MnS and CuS solids also catalyzed the reduction of 2,4-DNT to 4-A-2-NT. but did not change the overall reduction of 2,4-DNT. Howe ver, the presence of calcium, zinc, and magnesium minerals impeded 2,4 -DNT reduction. The calcium, zinc, and magnesium ions have a high affi nity to sulfide, inactivating sulfide as an electron donor for the che mical reduction of 2,4-DNT. Copyright (C) 1996 IAWQ.