Equilibrium adsorption of water-like molecules on single nanospheres

Abstract

Water-like gas adsorption on spherical nano-aerosol particles has been studied for particles of different sizes at different temperatures with density functional theory. The water-like fluid was modelled as Lennard–Jones (LJ) spheres with four hydrogen-bonding sites with parameters adjusted to the phase diagram of water. For the single sphere case, both the adsorption excesses and density profiles approach those of the plane cases as the spherical substrate sizes increase; at each temperature studied, the size dependence of the transition from thin-film adsorption to thick-film adsorption has been observed. What we found here support earlier suggestions (J. X. Fang, W. H. Marlow, J. X. Lu, and R. R. Lucchese, J. Chem. Phys. 107, 5212 (1997)) that not only the interaction energies between the water molecule and the spherical substrate are sensitive to the size of the spherical substrate, but also the wetting behaviour. In calculations of the excess adsorptions of particles of radii R = 20σ, 30σ, and 50σ, these substrates show the expected transition from the single molecule to the macroscopic aerosol particles.

Acknowledgements

This work was partially supported by the Texas A&M University Center for Atmosphere Chemistry and the Environment.