Molecular dynamics simulation of primary ammonium ions with different alkyl chains on the muscovite (001) surface

Molecular dynamics simulations employing PCFF_phyllosilicate force field have been carried out to explore the adsorption of primary ammonium collectors on the muscovite (001) surface. The results show that primary ammonium ions coat the muscovite surface, they form a monolayer coating on the surface, irrespective of the alkyl chain length. By computing interaction energy between the ammonium ion and mica surface, we find that primary ammonium ions have the same interaction with the muscovite surface. Atomic density profiles for water molecules on muscovite surface are calculated, we reproduced an important conclusion with theoretical calculation that hydrophobic force for long alkyl chains is stronger than that for short chains. We find that ammonium ions form a relatively orientationally ordered structure with respect to the muscovite surface. The simulation reveals hydrogen bonds between head groups and bridging oxygen atoms are affected by water molecules around the head groups, however, the head groups still constrain themselves above the hexagonal ring of the muscovite surface. (C) 2015 Elsevier B.V. All rights reserved.