Molecular dynamics simulations of sorption of organic compounds at the clay mineral/aqueous solution interface

✍ Scribed by Teppen, Brian J.; Yu, Ching-Hsing; Miller, David M.; Sch�fer, Lothar

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 759 KB
• Volume: 19
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/(sici)1096-987x(19980130)19:2<144::aid-jcc7>3.0.co;2-u

✦ Synopsis

The adsorption of trichloroethene, C HCl , on clay mineral 2 3

surfaces in the presence of water has been modeled as an example describing a general program that uses molecular dynamics simulations to study the sorption of organic materials at the clay mineralraqueous solution interface. Surfaces of the clay minerals kaolinite and pyrophyllite were hydrated at different water levels corresponding to partial and complete monolayers of water. In agreement with experimental trends, water was found to outcompete C HCl for clay 2 3 surface sites. The simulations suggest that at least three distinct mechanisms coexist for C HCl on clay minerals in the environment. The most stable 2 3 interaction of C HCl with clay surfaces is by full molecular contact, coplanar 2 3

with the basal surface. This kind of interaction is suppressed by increasing water loads. A second less stable and more reversible interaction involves adsorption through single-atom contact between one Cl atom and the surface. In a third mechanism, adsorbed C HCl never contacts the clay directly but sorbs onto the 2 3 first water layer. To test the efficacy of existing force field parameters of organic compounds in solid state simulations, molecular dynamics simulations of several