(289g) Molecular Simulation of Water Adsorption in Silicalite: Effect of Silanol Groups and Different Cations

Our research is focused on the separation of hazardous organics from water using nanoporous materials, such as zeolites. Molecular simulations can be used to study the adsorption of these materials from water. This way exposure to the contaminant material can be avoided or minimized. Silicalite was shown to adsorb chlorinated organics and MTBE more than activated carbon does, particularly at lower concentrations (1,2). It is important to simulate the adsorption of water in silicalite successfully in order to understand how water interferes with the adsorption of hazardous organics from water. We have made grand canonical Monte Carlo (GCMC) simulations to see the effect of defects on the adsorption of water in silicalite. The results have shown that defect-free silicalite is a very hydrophobic material adsorbing insignificant amount of water. However, even introducing only one silanol group per unit cell increases the amount of water adsorbed significantly. We also simulated the effect of different cations, H+, Na+, Li+ and Cs+, on the adsorption of water, and noted their effects on water adsorption. Here we present our results in comparison with experimental data.

1. Arjan Giaya , Robert W. Thompson , Raymond Denkewicz Jr., Microporous and Mesoporous Materials, 40, (2000) 205-218.

2. Ayse Erdem-Senatalar, John A. Bergendahl, Arjan Giaya, and Robert W. Thompson, Environmental Engineering Science, 21, (2004) 722-729.