MOLECULAR MODELING OF ADSORPTION OF POLLUTANT GASES ON CADMIUM-CONTAINING POLYACRYLONITRILE

Abstract

The paper presents theoretical studies of the adsorption of pollutant gases on the surface of cadmium-containing polyacrylonitrile (Cd-polyacrylonitrile) in the absence and presence of water molecules and oxygen molecules in the environment. The list of gases to which the Cd-polyacrylonitrile surface may have the highest sensitivity is determined. Nitrogen dioxide, methane, ammonia, sulfur oxide (II), hydrogen sulfide, ozone, carbon monoxide, carbon oxide (II), chlorine were chosen as pollutant gases. The following software packages are used for modeling: HyperChem, Gaussian 09, Сhemoffice 2010. Polyacrylonitrile macromolecule models were obtained from HyperChem, Gaussian 09, from which a pentamer macromolecule was chosen to produce a Cd-polyacrylonitrile cluster. Then, implementing the molecular mechanics method in Сhemoffice 2010, namely in the Chem3D subroutine, the Cd-polyacrylonitrile cluster model is constructed. Further, using the molecular modeling method, the following thermodynamic parameters were determined: «Cd-polyacrylonitrile cluster – gas molecule», «Cd-polyacrylonitrile cluster – oxygen molecule», «Cd-polyacrylonitrile cluster – water molecule», «Cd-polyacrylonitrile cluster – oxygen molecule gas molecule», «Cd-polyacrylonitrile cluster – water molecule – gas molecule». As a result of molecular modeling, it was established that Cd-polyacrylonitrile in the atmospheric air exhibits selective sensitivity to gaseous chlorine and carbon monoxide; in an oxygen-free environment – also to hydrogen sulfide. The results of molecular modeling confirm the previously obtained experimental data on the evaluation of the gas sensitivity of Cd-polyacrylonitrile and indicate the presence of van der Waals forces between the Cd-polyacrylonitrile and the adsorbed gas molecule. The presence or absence of water molecules in atmospheric air should not affect the change in the sensitivity of Cd-polyacrylonitrile to pollutant gases.