Borohydride Photoreduction of Nitroaromatic Compounds Related to Military Ordnance Constituents

• Published in: Environmental science & technology 1996-04, Vol.30 (4), p.1192-1197
• Main Authors: Larson, Richard A, Miller, Penney L, Crowley, Thomas O
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Exact sciences and technology; Other wastes and particular components of wastes; Pollution; Wastes
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es950415y

Nitroaromatic compounds are pollutants of considerable concern due to their toxicity and the extent of their use as synthetic intermediates, propellants, and explosives. Oxidative methods for treating wastes containing these compounds are not entirely satisfactory because of the recalcitrant nature of the compounds toward aerobic microbial decomposition and common chemical oxidizing agents. Recently, several publications have appeared indicating that these substances are susceptible to microbial reduction under anaerobic conditions. We have evaluated the chemical reduction of these compounds using alkaline sodium borohydride. In the presence of excess borohydride, exposure of the compounds to ultraviolet wavelengths >280 nm strongly promoted their decomposition. Rates of disappearance for four tested nitroaromatic compounds were increased even more if the illumination was conducted in the absence of oxygen. Numerous denitration, desulfonation, reduction, and condensation products were tentatively identified from the reaction mixture. The photoreaction appeared to occur by a mechanism including electron transfer from borohydride to an excited state of the nitro compound.