Effects of Size, Shape, and Polarity of Components in the Binary Mixture of Ionic Liquid [C₄mim][Cl] and 1,4-Dioxane on Molar Excess Enthalpies and Volume at Different Temperatures

Abstract

This study presents a detailed thermodynamic investigation of binary mixtures composed of the ionic liquid 1-butyl-3-methylimidazolium chloride ([C₄mim][Cl]) and the cyclic ether 1,4-dioxane, with a focus on understanding the influence of molecular size, shape, and polarity on excess molar enthalpy (Hᴇ) and excess molar volume (Vᴇ). Experimental measurements were conducted over a wide mole fraction range at three temperatures: 298.15 K, 308.15 K, and 318.15 K, under atmospheric pressure. The results reveal consistent negative values of Hᴇ and Vᴇ across all compositions and temperatures, indicating strong exothermic interactions and volume contraction upon mixing.