Extraction of Nitric Acid with a Monoamide: Understanding Study and Thermodynamic Modeling

The extraction of HNO3 by the monoamide MOEHA was investigated, challenging speciation and thus nitric acid extraction modeling in the organic phases. Batch experiments were conducted to measure the distribution of HNO3 and water between the two phases and acquire infrared (IR) spectra to elucidate the HNO3 organic phase speciation. Additionally, molecular dynamics (MD) simulations allowed the identification of three complexes using graph theory. Density Functional Theory (DFT) was used to confirm the stability of those species and to determine their theoretical IR spectra. It was shown that 3 distinct spectra should be observed. The data served as input for principal component analysis (PCA) deconvolution of IR spectra, confirming the presence of three major species. The thermodynamic model was then modified taking into account these data to fit both the speciation data acquired through PCA and the distribution data.