Suggested improvements in the parameters used for describing the low relative pressure region of the water vapour isotherms of activated carbons

The Do and Do model for water adsorption isotherms of activated carbons has been refined, linking its parameters to the amount of surface oxygenated and nitrogenated complexes on the carbon. As these values can be determined independently, e.g. by X-ray photoelectron spectroscopy, it is possible to predict the water isotherm of an activated carbon or, vice versa, use the water vapour isotherm to characterise its surface functionality. During testing it has been shown that activated carbons that have been heat treated to render them more hydrophobic can be reoxidised by ambient air and become more hydrophilic.