SOLUTION, APPARENT AND RELATIVE MOLAR ENTHALPIES FOR TWO MODEL IONIC LIQUID + WATER SYSTEMS IN THE RANGE OF 303.15 - 318.15 K AND OF HIGH DILUTION

摘要

Experimental enthalpies of solution, Δ_sH_(m,mix) , for l-butyl-3-methylimidazolium bromide ([bmim]Br) + water system measured by using a SETARAM C80 3D calorimeter with reversal mixing mechanism over the composition range from m = 0.0059 to 0.9646 mol kg~(-1) of [bmim]Br at temperatures of 303.15, 310.15 and 318.15 K and atmospheric pressure are reported. The data have been correlated adequately with Archer and Rard (1998) model for electrolyte systems. The absolute mean relative deviations obtained in the ionic liquid (IL) molar enthalpy of solution correlation were situated between 6.8% and 22.0%, decreasing with increasing temperature. The molar enthalpies of solution at infinite dilution, the apparent relative molar enthalpies for the solute and relative molar enthalpies for the mixtures were determined according to this model. The results are compared with those obtained for the l-butyl-3-methylimidazolium chloride ([bmim]Cl) + water system for which the experimental data with inadequate modeling were published recently (Teodorescu and Popa (2016)) and that are adequately correlated in the present work with 3.8% absolute mean relative deviations by Silvester and Pitzer (1977) electrolytes model. The physical interactions in the two ionic liquids (ILs) aqueous solutions are briefly analyzed, based on the obtained results.