Thermophysical Properties of Newly Synthesized Ammonium-Based Protic Ionic Liquids: Effect of Temperature, Anion and Alkyl Chain Length

Processes

MohamadAzmi Bustam¹  NormawatiM. Yunus²  AsyrafHanim Ab Rahim²  NurHidayah Zulaikha Othman Zailani² 

[1] Department of Chemical Engineering, Center of Research in Ionic Liquids (CORIL), Institute of Contaminant Management for Oil and Gas, Universiti Teknologi PETRONAS, Seri Iskandar 32610, Malaysia;Department of Fundamental and Applied Sciences, Center of Research in Ionic Liquids (CORIL), Institute of Contaminant Management for Oil and Gas, Universiti Teknologi PETRONAS, Seri Iskandar 32610, Malaysia;

关键词: protic ionic liquids;    density;    viscosity;    refractive index;    phase transition;    thermal expansion coefficient;   

DOI  :  10.3390/pr8060742

来源: DOAJ

【 摘 要 】

Ionic liquids which are often classified as low melting point salts have received significant attention from research groups and industries to be used in a wide range of applications. Many of these applications require thorough knowledge on the thermophysical properties of the ionic liquids before utilizing their full potentials in various fields. In this work, a series of alkylammonium cation and carboxylate anion-based room temperature protic ionic liquids (PILs) were synthesized by varying length of alkyl chain of the cation from diethyl to dibutyl combined with pentanoate, hexanoate and heptanoate anions. These ammonium-based PILs named as diethylammonium pentanoate [DEA][C5], diethylammonium hexanoate [DEA][C6], diethylammonium heptanoate [DEA][C7], dibutylammonium pentanoate [DBA][C5], dibutylammonium hexanoate [DBA][C6] and dibutylammonium heptanoate [DBA][C7] were characterized using Nuclear Magnetic Resonance (NMR) spectroscopy. The thermophysical properties of the PILs namely density, dynamic viscosity and refractive index were measured and analyzed. Density, ρ and dynamic viscosity, η were determined at T = (293.15 to 363.15) K and refractive index, n_D was measured at T = (293.15 to 333.15) K. The fitting parameters are proposed for the empirical correlations of density, dynamic viscosity and refractive index. The values of thermal expansion coefficient, α_p, molecular volume, V_m, standard entropy, S° and lattice potential energy, U_pot also have been calculated by using the specified equations. The thermal decomposition temperature, T_d was also determined using a thermogravimetric analyzer (TGA) while the differential scanning calorimetry (DSC) technique provided the glass transition, T_g, melting point, T_m and crystallization, T_c temperatures of the PILs. The experimental results revealed that the dependency of the experimental values namely the ρ, η, n_D, and T_d on the alkyl chain of the anion, size of the cations and the temperature of measurement.

【 授权许可】

Unknown