Nitric Acid and Water Extraction by T2EHDGA inn-Dodecane

Liquid–liquid distribution behavior of nitric acid (HNO3) and water by a diglycolamide (DGA) ligand, N,N,N’,N’-tetra-2-ethylhexyldiglycolamide (T2EHDGA), into n-dodecane diluent was investigated. Spectroscopic Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) characterization of the organic extraction solutions indicate the T2EHDGA carbonyl coordinates with HNO3 and progressively aggregates at high acid conditions. Water extraction increases in the presence of HNO3. The experimentally observed distribution of HNO3 was modeled using the computer program SXLSQI. The results indicated that the formation of two organic-phase species—HNO3·T2EHDGA and (HNO3)2·T2EHDGA—satisfactorily describes the acid distribution behavior. Temperature-dependent solvent extraction studies allowed for the determination of thermodynamic extraction constants and ΔH and ΔS parameters for the corresponding extractive processes.