Kinetic Studies on the Green and Practical Iodide-mediated Dealkylation of Tributylphosphate (TBP) using Nuclear Magnetic Resonance Spectroscopy

Abstract

The rapid degradation of the highly persistent chemical tributylphosphate (TBP) using the ecofriendly and inexpensive salt potassium iodide is described. The process involves the dealkylation of TBP at 100°C in dimethylsulfoxide (DMSO), representing the most rapid and mildest conditions for its breakdown reported to date. The reaction follows pseudo-first order kinetics with a half-life of t½ = 4.72 ± 0.41 h. Furthermore, in an attempt to closely mimic conditions encountered during the PUREX process in nuclear power plants, we conducted the reaction in a 1:1 dodecane:DMSO mixture. Under these conditions, TBP was found to still degrade, albeit at a slower rate than in pure DMSO with a half-life of t½ = 16.2 ± 0.4 h. The process represents the first step in the degradation of TBP into inorganic phosphate that, due to its mild and eco-friendly nature can be adapted to a large-scale operation.