Hydration of alcohol clusters in 1-propanol-water mixture studied by quasielastic neutron scattering and an interpretation of anomalous excess partial molar volume

Abstract

Quasielastic neutron scattering measurements have been made for 1-propanol-water mixtures in a range of alcohol concentration from 0.0 to 0.167 in mole fraction at 25 degrees C. Fraction alpha of water molecules hydrated to fractal surface of alcohol clusters in 1-propanol-water mixture was obtained as a function of alcohol concentration. Average hydration number N(ws) of 1-propanol molecule is derived from the value of alpha as a function of alcohol concentration. By extrapolating N(ws) to infinite dilution, we obtain values of 12-13 as hydration number of isolated 1-propanol molecule. A simple interpretation of structural origin of anomalous excess partial molar volume of water is proposed and as a result a simple equation for the excess partial molar volume is deduced in terms of alpha. Calculated values of the excess partial molar volumes of water and 1-propanol and the excess molar volume of the mixture are in good agreement with experimental values.

Aggregation kinetics of latex microspheres in alcohol–water media

“…Notwithstanding, it is very difficult to give plausible explanations to the very complex behavior here reported. As mentioned in the introduction, one important difference between 1-propanol-and methanolwater mixtures is that in the first case, 1-propanol clusters grow, forming fractal structures [4]. These fractal aggregates, if large enough, may play the role of polymers [37,38], producing a sufficiently large depletion contribution to compensate for the enhancement of the zeta potential.…”

“…These clusters are, in turn, joined by bridging water molecules. Furthermore, these clusters may grow forming large fractal-like structures for 1-propanol [4]. This structuring will be, to some extent, perturbed by the presence of the colloidal particles.…”

A visualized analysis of small-angle neutron scattering intensity: concentration fluctuation in alcohol–water mixtures

“…Therefore, the increase of concentration fluctuation is simply attributed to the increase in cluster size. Quasi-elastic neutron scattering measurements on the 1-propanol-water mixtures strongly suggests the existence of lessmobile water molecules around the non-polar group of the alcohol molecule (Misawa et al, 2006). These water molecules may form a sort of 'clathrate-like' structure around the alcohol molecule and are in a low-entropy state compared to bulk water (Frank & Evans, 1945;Stillinger, 1980;Koga et al, 2004).…”

Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering

“…4 Similar non-monotonic concentration dependences of viscosity related dynamics have been observed for alcoholwater mixtures, [5][6][7] although in these systems they have been attributed to the hydrophobic interaction between alcohol molecules and surrounding water molecules. [8][9][10][11] This gives rise to both slower water dynamics [12][13][14] and a higher local average density [8][9][10][11] of the two molecular water layers closest to the alcohol molecules. In fact, the local density of the water and its molecular dynamics seems to be strongly related.…”