Management of spent solvents by alkaline hydrolysis process

This paper deals with the treatment method for the management of spent solvents of reprocessing origin (30% tri-n-butyl phosphate in n-dodecane) using the ‘alkaline hydrolysis process’. The consolidated work reported herein has established total conversion of TBP to aqueous soluble reaction products and transfer of near total radioactivity associated with the waste into this aqueous phase. It was also observed that n-dodecane (diluent) did not take part in the reaction and separated out as the top layer. Repeated runs have established the process on engineering scale (up to 200 l/batch) with regard to conversion of TBP into sodium salt of HDBP, butanol and recovery of the diluent practically free of TBP. The measured parameters, specifically, temperature and pressure did not deviate from set limits during the entire reaction time indicating safe operation. Experiments were also carried out on immobilization of the aqueous phase resulting from hydrolysis which contains almost all the radioactivity associated with the original spent solvent. These immobilization studies have established compatibility of the process generated aqueous stream with cementitious matrix.