Modified carbon multiwall nanotubes were prepared via the oxidation process by means of 65% nitric acid or ferric nitrate
dissolved with 65% nitric acid. Using special thermogravimetry and sorptometry methods physicochemical properties of pure
and modified nanotube surfaces were investigated. A numerical and analytical procedure for the evaluation of total heterogeneous
properties on the basis of liquid thermodesorption from the sample surfaces under the quasi-equilibrium conditions are presented.
The calculations of the fractal dimensions of carbon nanotubes using the sorptometry and thermogravimetry data is presented.