Noura Dawass

5 112 P ROPERTIES OF U REA -C HOLINE C HLORIDE M IXTURES 5.4. C ONCLUSIONS In this chapter, properties of mixtures of ChCl and urea were computed at dif- ferent molar ratios. MD simulations in the NPT ensemble were carried out to compute RDFs of systems of urea, choline and chloride. RDFs were corrected for finite size effects using the van der Vegt and Gaungly correction [167] . To compute KBIs, the system was treated as pseudo-binary were ions are indistin- guishable. KBIs in the thermodynamic limit were estimated and used to examine the affinity between the components of the mixture. As the mole fraction of urea increases, the affinity between pairs of urea-urea increases. Also, urea-ChCl and ChChl interactions are weakened as a result of increasing the content of urea. Other than studying molecular interactions, KBIs were used to compute thermo- dynamic factors and partial molar volumes. Partial molar volumes were hardly affected by the change in the mole fraction of urea in sharp contrast to thermo- dynamic factors and transport properties. From MD simulations, the following transport properties were also computed as a function of composition: viscosity, self diffusion coefficients, MS diffusivities and ionic conductivities. With higher mobility of urea, choline and chloride, the viscosity of the mixtures decreased with increasing mole fraction of urea. Self and binary diffusivities were found to increase by increasing the content of urea.