Surface fractal dimension of thermally treated peat soils from adsorption isotherms of nitrogen

Adsorption isotherms of nitrogen at 80 K were measured on thermally modifie d peat soils. The isotherms were used to evaluate the surface fractal dimen sion from the Frenkel-Halsey-Hill equation. We also tested if surface chara cteristics were correlated to the water holding capacity index, which chara cterizes the degree of the secondary transformation of pear soils. In most cases the thermal treatment lowered the value of the surface fractal dimens ion, i.e. diminished the roughness of the part of the surface that adsorbs nitrogen molecules.