Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

In this paper, four natural deep eutectic solvents (NADES) systems were prepared at specific molar ratios, La:Bet (2:1) (lactic acid : betaine), La:Hist (9:1) (lactic acid : histidine), Ma:Bet:H2O (1:2:3) (malic acid : betaine : water) and Ma:Bet:Pro:H2O (1:1:1:2) (malic acid : betaine : proline : water). Their physical and thermodynamic properties were studied, namely viscosity, electrical conductivity, heat capacity, vaporization enthalpy and vapour pressure. The viscosity and electrical conductivity were determined as function of temperature and the correlation for the temperature dependence was obtained and discussed based on Arrhenius theory. The heat capacity for all eutectic systems was measured by differential scanning calorimetry (DSC) over a temperature range of 293.15 K to 363.15 K. The standard molar vaporization enthalpy and vapour pressure of La:Bet (2:1) and La:Hist (9:1) were determined by thermogravimetric analysis (TGA). The ability of these NADES to reduce cellulose crystallinity was evaluated. Cellulose crystallinity after suspension in these NADES was studied by X-ray diffraction. Cellulose suspended in Ma:Bet (1:2) suffer the highest crystallinity reduction of 20%.