Vapor adsorption on coal- and wood-based chemically activated carbons: (I) Surface oxidation states and adsorption of H2O Original Research Article

X-ray photoelectron spectroscopy (XPS) was employed to evaluate the surface element distribution/concentration and surface chemical structure of coal- and wood-based chemically activated carbons and to investigate the effect of these features on the adsorption of water vapor at low relative pressure and room temperature. It was found that high surface area carbon samples generally show low concentrations of surface oxygen and low surface area carbon samples generally show high concentrations of surface oxygen. The concentrations of carbon surface oxygen groups such as C–O and CO generally decrease with increasing heat treatment temperature. Increased water vapor adsorption on the lower surface area activated carbons can be correlated with higher concentrations of surface oxygen functional groups.