Toward solvent selection for the extractive removal of pyridine from fuels using ionic liquids: A QSPR study

In the present study, the distribution of pyridine between the ionic liquid (IL)-rich phase and hydrocarbon-rich phase has been predicted using the quantitative structure–property relationship (QSPR) approach. After a comprehensive survey in the literature, a large dataset including 51 ternary systems (i.e., IL (1), pyridine (2), and hydrocarbon (3)) was collected. The present dataset covers 19 cations, 14 anions, and 10 hydrocarbons. Therefore, the structural effect of each cation, anion, and hydrocarbon has been taken into account on the prediction of pyridine distribution between the IL-rich phase and hydrocarbon-rich phase. Multiple linear regression (MLR) and multi-layer perceptron (MLP) have been employed to develop the predictive/descriptive linear and non-linear models, respectively. Results showed that the final linear model (R² = 0.9165, %AARD = 23.2722) and non-linear model (R² = 0.9892, %AARD = 9.1936) have an acceptable prediction capability. By interpreting the selected descriptors of the QSPR model, the effect of changes in the cation, anion, and hydrocarbon structures on the extraction of pyridine was also studied. It was found that the size, branches, and cyclic or acyclic structure of hydrocarbons were important parameters affecting the pyridine distribution. Also, the size, branches, and position of the electronegative atoms (especially oxygen atoms) in the structure of anions as well as the alkyl side chain length and C-N bonds in the structure of cations could also affect the pyridine distribution.