Equation of state for ionic liquids

A simple form of equation of state for ionic liquids is proposed as an asymptotic low-temperature variant of the fluctuational equation of state developed by author. This function predicts reliably the properties of the pure substances and mixtures with the quite different molecular structures in the wide temperature- and pressure-ranges including the critical region. It is essentially important at evaluation, for example, of the near-critical carbon-dioxide's solubility in the set of ionic liquids. Re-establishing of the gas-liquid phase diagram from the triple point up to the point of thermal decomposition on the base of measurable data at atmospheric pressure has been chosen as the method for the thermodynamically-consistent calculation of coefficients. Especially complex problem is the consistent description of very small values of isothermal compressibility and vapor pressure. The developed method is verified for water, ethylene, argon and several ionic liquids. It is applicable, in principle, to such complex molecular structures as polymers, non-organic salts, liquid metals for which the equation of state is necessary to solve a variety of the practical usage questions.