Distinct water behaviors at the surfaces of siloxane and gibbsite layers: Response to the concentration and cation type

Abstract

Gibbsite and siloxane layers are ubiquitous in soil and sediments, however, distinct water behaviors at these surfaces in response to concentration and cation type are still unclear. Molecular method was performed to simulate the aqueous solutions interacting with both the siloxane and gibbsite surfaces of kaolinite. Despite cations were primarily adsorbed on the siloxane surface, they can still regulate the anions adsorption on the gibbsite surface through correlation effect, thereby altering the water behaviors. Cation effect on the atomic density and angle distribution of water molecules was greater at the gibbsite than the siloxane surface, but the concentration effect on these properties was similar. Both concentration and cation effect on hydrogen bonds were more pronounced at the gibbsite surface, however, cation effect was more evident at the siloxane than at the gibbsite surface. The findings are useful in understanding the water availability in soil aggregates containing different clay layers.