WATER IN POROUS CARBONS: A SIMULATION STUDY

摘要

We present a simulation study of the adsorption mechanism of water in a realistic carbon structure at 300 K. Water molecules are modeled using a recently developed fixed-point charge water model optimized to the vapor-liquid coexistence properties (Errington and Panagiotopoulos, 1998). Reverse Monte Carlo techniques (Thomson and Gubbins, 2000) are used to generate a realistic model of carbon pore morphologies composed of rigid, carbon basal plates. Arrangements of the carbon plates are driven by a systematic refinement of simulated C-C radial distribution functions to match experiment. The resulting pore morphology is generally non-slitlike and highly connected. The adsorption of water on activated (surface oxygen sites, =O) and non-activated (graphitic) carbon is investigated using the grand canonical Monte Carlo simulation method. The adsorption behavior is found to be strongly dependent on the presence of active sites with no appreciable adsorption in the graphitic carbon until the pressure is above the bulk saturation point. Additionally, water adsorption is found to increase as the active site density increases.