Preparation and Evaluation of Powdered Activated Carbon from Lignocellulosic Materials

摘要

This research project was conceived as a preliminary evaluation of the technical feasibility of converting solid wastes into adsorbents suitable for wastewater treatment. The work emphasized the pyrolysis of solid wastes rich in organic constituents, mainly agricultural wastes. The char prepared from one of these materials (prune pits) was subsequently activated for comparison with activated carbons that are widely used in water and wastewater treatment. The chars so prepared showed specific surface areas of 300 to 650 sqm/g, measured by CO2-BET adsorption (195K), but the pores were so small that the solids were penetrated only slowly by N2. Pyrolysis at 700 to 900C resulted in a greater char specific surface than did pyrolysis at 500C. The activated carbons made from prune pits demonstrated favorable adsorption performance, when compared with an activated carbon widely used in water and wastewater treatment. The prune pit char activated at 60 min. demonstrated a higher adsorption capacity and superior adsorption kinetics compared to the commercial product (Filtrasorb 400), when judged according to the uptake of dissolved organic carbon (DOC) from secondary effluent. This difference coincided with a greater surface area and macro- and transitional (3 to 300 nm) pore volume for the activated carbon made from prune pits. An adsorbent made by activation of prune pit char for 42 min. was approximately equivalent to Filtrasorb 400 in every respect.