Use of kinetic H2O-adsorption isotherms for the determination of specific surface areas of fully hydroxylated mesoporous silicas

It has recently been shown that fully hydroxylated mesoporous silicas adsorb precisely one monolayer of water from ∼50% relative humidity air at ∼22 °C. The resulting H2O monolayer concentration of 7.68 μmol H2O/m2 can be used to determine the specific surface areas of such silicas. Fifteen different silicas, having average pore sizes in the range from 3 to 100 nm, were tested. Silicas having pore sizes >3 nm gave specific areas in good agreement with those obtained by the usual BET(N2) procedure.