Temperature- switchable ammonium acetate/diethylene glycol deep eutectic solvent for selective and green separation of cyclotetramethylenetetranitramine (HMX) and cyclotrimethylenetrinitramine (RDX) explosives

A green and low-cost deep eutectic solvent (DES) composed of ammonium acetate and diethylene glycol (DEG) was developed for selective separation of two similar structures cyclotetramethylenetetranitramine (HMX) and cyclotrimethylenetrinitramine (RDX) explosives. The influence of DES on the solubility of two explosives was statistically investigated by central composite design (CCD) of experiment, and some solubility parameters including activity coefficient, dissolving enthalpy, and mixing enthalpy for RDX and HMX were determined. Empirical findings indicated that the dissolution ratio of RDX to HMX in DES varied between 10.0 and 30.0 times. This enables the development of a specific and successive leaching approach for green and selective extraction of two explosives produced in Bachmann nitration process with separation efficiency of greater than 98.1% and purity of HMX greater than 99.5%. Additionally, interactions of DES components and quality of products were evaluated using Fourier transform infrared spectroscopy (FT-IR), dielectric constants measuring over 100.0 Hz - 1.0 MHz, X-ray diffraction (XRD), high-performance liquid chromatography (HPLC), and laser-induced breakdown spectroscopy (LIBS). The suggested approach allows the preparation of pure RDX and HMX explosives in an effective, safe, and environmentally friendly manner, for using in oil well perforation.