abstract
The thermophysical properties including density, heat capacity, thermal stability and phase behaviour of protic ionic liquids based on the N-methyl-2-hydroxyethylammonium cation, [C2OHC1NH2](+), with the carboxylate anions (propionate, [C2COO] , butyrate, [C3COO] , and pentanoate, [C4COO] ) are reported and used to evaluate structure-property relationships. The density was measured over the temperature and pressure ranges, T = (298.15 to 358.15) K and p = (0.1 to 25) MPa, respectively, with an estimated uncertainty of +/- 0.5 kg . m(-3). The pressure dependency of the density for these ionic liquids (ILs) is here presented for the first time and was correlated using the Goharshadi-Morsali-Abbaspour (GMA) equation of state, from which the isothermal compressibility, thermal expansivity, thermal pressure, and internal pressure were calculated. The experimental PVT data of the protic ILs were predicted by the methods of Gardas and Coutinho (GC), and Paduszynki and Domanska (PD). The thermal stability was assessed by high resolution modulated thermogravimetric analysis within the range T = (303 to 873) K. The heat capacity was measured in the temperature range T = (286.15 to 335.15) K by modulated differential scanning calorimetry with an uncertainty in the range (1 to 5) J . K-1 . mol(-1). The Joback method for the prediction of ideal gas heat capacities was extended to the ILs and the corresponding states principle was employed to the subsequent calculation of liquid heat capacity based on critical properties predicted using the modified Lydersen-Joback-Reid method. The Valderrama's mass connectivity index method was also used for liquid heat capacity predictions. This series of N-methyl-2-hydroxyethylammonium was used to establish the effect of the anion alkyl chain length on the ionic liquid properties. (C) 2013 Elsevier Ltd. All rights reserved.
keywords
ETHYLAMMONIUM NITRATE; PHYSICOCHEMICAL PROPERTIES; HEAT-CAPACITY; FUSED SALT; TRIETHANOLAMINE STEARATE; KNOEVENAGEL CONDENSATION; ETHANOLAMINE OLEATE; PHASE-BEHAVIOR; WIDE-RANGE; ACID SOAP
subject category
Thermodynamics; Chemistry
authors
Talavera-Prieto, NMC; Ferreira, AGM; Simoes, PN; Carvalho, PJ; Mattedi, S; Coutinho, JAP
our authors
Pedro J. Carvalho
Assistant Professoracknowledgements
The authors are grateful to UE Mobility Programme which supported the Grant (EADIC II - ERASMUS MUNDUS ACTION 2 LOT 13A UE Mobility Programme 2010-2401/001-001 - EMA2) and to the Fundacao para a Ciencia e a Tecnologia which funded CICECO through Pest-C/CTM/LA0011/2011. S. Mattedi is grateful to CNPq (Project 475883/2012-8) and UFBA (Project PROPI/2013) for funding her work. The authors acknowledge the support from Eng. Paula V. Egas for her assistance in the ILs management.