Reactive thermal hazards of irradiated tributyl phosphate with nitric acid

Red oil incidents reported worldwide are attributed to the reactive thermal reactions between Tributyl phosphate (TBP) and nitric acid. The vigor of thermal behavior may be influenced by various factors including irradiation, presence of metal nitrates etc. This work is focused to study the influence of irradiation on the reactive thermal behavior of 30% TBP with varying strengths of HNO3 for the first time. The Accelerating Rate Calorimetry (ARC) studies reveal that irradiated 30% TBP reacts exothermically with 4 mol/L–16 mol/L HNO3 and contributes to rise in system pressure. A lower onset temperature for exothermic reaction was noticed in irradiated TBP compared to the non-irradiated 30% TBP with acid. From the Zero-Order kinetic model, the TMRad for irradiated and non-irradiated TBP 4 mol/L HNO3 system was been determined for thermal hazard assessment. FT-IR, NMR and GC–MS characterization of the residues of ARC clearly suggest that conversion of butanol to butanoic acid is the exothermic red-oil forming reaction.