Water as a potential molecular probe for functional groups on carbon surfaces

A new and simple method, using water as a potential molecular probe, is proposed for the determination of the concentration of surface oxygen groups on carbon adsorbents. The procedure is based on a determination of the Henry constant between a water molecule and a functional group from the volume integration of the Boltzmann factor over the accessible space around the functional group. Three porous carbons are used in this study to test the new method: A-5, RF-100 and RF-200. The results obtained are in good agreement with those measured by Boehm titration. This new method can be applied to adsorbents containing small concentrations of oxygen groups where the Boehm titration method may give unreliable results.