Viscosities, Free Energies of Activation and their Excess Properties in the Binary Mixtures of Some Monoalkanolamines with Acetonitrile between 303.15 and 323.15 K: Experimental and Correlative Approach

Abstract

Viscosities (h) of three binary non-aqueous systems of ACN + MEA, + MMEA and + MEEA have been measured in the whole range of compositions at temperatures ranging between 303.15 and 323.15 K at an interval of 5 K. At different compositions, deviations in viscosity (Dh), free energy (ΔG‡) of activation for viscous flow along its excess values (ΔG‡E) were calculated from experimental ρ andh data. For all systems, h vs. x2 initially changed very slowly, but with the increment of solute concentration h were found to rise quite rapidly. The values of Dh were largely positive and they formed a sharp maximum invariably at the highly alkanolamine-rich regions. All positive values of Dh followed the increasing order as: ACN + MMEA > ACN + MEA > ACN + MEEA. The order of DG‡E at the maximum point was ACN + MMEA > ACN + MEA > ACN + MEEA. For the correlative model, zero parameter relations: Bingham, Kendall- Munroe, Gambill, and Eyring relations, one parameter relations: Hind, Grunberg-Nissan, Frenkel, Wijk, Katti-Chaudhri, Tamura Kurata and two as well as three parameter-based models: Heric, Ausländer, McAllister (3-body) and McAllister (4-body) Equation and the Jouyban-Acree model (JA) were employed to correlate viscosities. Ausländer equation fit the best for: ACN + MEA. McAlliester 4-body fit the best for ACN + MMEA and ACN + MEEA. All the above results were attempted to be interpreted in terms of the strength and order of self-association, intra- as well as intermolecular hydrogen bonding via OH···O or OH···N and the effect due to steric hindrance of the concerned alkanolamine molecules and interstitial accommodation of ACN into alkanolamine network.

Keywords

• Viscosity, Deviation in viscosity, Excess free energy of activation for viscous flow, Correlative model, Alkanolamine, Cross H-bonding