INFLUENCE OF PYROLYSIS TEMPERATURE ON THE ADSORPTIVE PROPERTIES OF ADSORBENTS PRODUCED FROM NOVOLAC AND BIOMASS

Mixtures of novolac resin and olive stone biomass are cured and pyrolyzed at different temperatures to yield carbonaceous adsorbents. The weight losses and the shrinkages taking place in the carbonization process increase up to ca. 600 degrees C. The pyrolysis residues are investigated with respect to their ability to adsorb toluene and cyclohexane from the vapor phase. Toluene is adsorbed on all adsorbents stronger than cyclohexane. The overall diffusion coefficient D of the adsorption process, the specific surface area, and the pore volume of the adsorbents are calculated. The adsorptive properties of the products are interpreted taking into account the size and shape of the pores, the polarity of the adsorbate, and the dispersion forces between adsorbent and adsorbate. Slit-shaped pores, which are charac--- teristic of carbon molecular sieves, are likely to be present in the adsorbents which are pyrolyzed at higher temperatures and particularly at 1000 degrees C. This adsorbent shows the highest adsorption concerning the equilibrium uptake, specific surface area, and pore volume of toluene and cyclohexane. However, the diffusion coefficient D is lower as more micropores are present. (C) 1995 John Wiley and Sons, Inc.