Pyrolysis of apple pulp:: chemical activation with phosphoric acid

Chemical activation of apple pulp with phosphoric acid has been carried out to prepare activated carbons. The materials were characterized by elemental analysis, N-2 adsorption (77 K), CO2 adsorption (273 K) and X-ray diffraction. The effects of temperature, soaking time, impregnation ratio and degree of washing were studied. Maximum development of porosity was observed upon beating to 723 K plus 1 h soaking. The amount of phosphoric acid used in the impregnation step strongly influenced the porous texture, micropores being predominant at low impregnation ratios whereas larger amounts of phosphoric acid produced wide micropores and mesopores. The washing sep also had a crucial effect on the porosity accessible to different adsorbates. The results suggest the feasibility of the process from the point of view of both porous texture and carbon yield. (C) 2002 Elsevier Science B.V. All rights reserved.