Analysis of nitrogen sorption data of chemically activated carbon by the application of adsorption models based on surface coverage and volume filling of micropores. 1. Phosphoric acid activated carbons

Activated carbons were prepared by carbonizing ground apricot stones impregnated with 20-60 wt% phosphoric acid at 300-600 degrees C, in a limited air supply. Highly activated carbons with surface areas amounting to 1200 m(2)/g and pore radii of 8-10 Angstrom were obtained when a mixture of apricot stones and 50 wt% phosphoric acid was carbonized at 450 degrees C, Activation with phosphoric acid proceeds via the creation of pores of radii between 8 Angstrom and 10 Angstrom. The adsorption data for nitrogen at 77 K obey models based on surface coverage satisfactorily and also models based on pore volume filling. Although a slight upward deviation was shown in the Dubinin-Radushkevich (DR) plots, this model was still verified and allowed the determination of useful sorption parameters.