AIChE Journal, Vol.54, No.9, 2479-2486, 2008
Adsorption from oversaturated aqueous solution: Mean force molecular simulations
The squeeze out of benzene from an aqueous solution to a planar graphite wall is considered by molecular simulations. The system contains 1-10 benzene molecules in water at T = 300 K and p = I bar corresponding to all oversaturation from 10 to 100. Local density profiles are obtained from the mean force method with a particle balance. For improving the accuracy, standard simulations results are incorporated into the mean force method. The resulting density profiles of benzene show a first peak at the wall with parallel and a second with perpendicular orientation of the molecules. For larger distances from the wall the structure levels out and for up to 40-fold oversaturation a limiting density of 25.8 +/- 3.6 mmol/l is obtained. This value is in surprisingly good agreement with the experimental solubility limit of 22.8 mmol/l. The method may also be used for obtaining liquid-liquid equilibria. (C) 2008 American Institute of Chemical Engineers.
Keywords:adsorption/liquid;phase equilibrium;aqueous solutions;computer simulations (MC or MD);thermodynamics/statistical