Ionic liquids: determination of their aqueous content using differential scanning calorimeter equipment, chaotic parameters and a radial basis network model

Abstract

A new computerized approach to the determination of water in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, 1-butyl-3-methylimidazolium hexafluorophosfate and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquids (ILs) using the differential scanning calorimeter (DSC) scans of their mixtures with water is presented here. This approach consists of a combination of chaotic algorithms and a radial basis network (RBN). The data collected (heat flow signal) from DSC scans of ILs and water mixtures are used to calculate six chaotic parameters (two Liapunov exponents, two correlation parameters and two fractal dimensions), and then, these values are transferred into an RBN trained computer for modeling and estimating output. The predicted results using the RBN were compared with the measurements of water content carried out by the Karl Fischer technique and the difference between the real and predicted values was less than 0.05 and 4.9% in the internal and external validation, respectively. Such an integrated chaotic parameters (CPs)/RBN system is capable of detecting and quantifying water content in the aforementioned ILs, based on the created models and patterns, without any previous knowledge of this thermal process.