Activated Carbon Preparation from Cassava Residue Using a Two-Step KOH Activation: Preparation, Micropore Structure and Adsorption Capacity

Activated carbon (AC) was prepared from cassava residue using a two-step activation, including carbonization and subsequent KOH activation. The conditions of activation were optimized through single factor and orthogonal experiments. Heating at 700 degrees C for 90 min resulted in a charcoal yield of 20%, the optimal condition for carbonization. Factors affecting surface area (S-BET) were KOH/char ratio > activation temperature > activation time. The porous structure of the AC was characterized using the physical adsorption of N-2 at 77 degrees C. AC with a SBET of 460-2655 m(2)/g and pore volume of 0.41-1.198 cm(3)/g were prepared. Prepared AC had a high proportion of micropores (range: 83.0-92.0%) compared to mesopores. The average diameters of the micropores and mesopores were in the range of 0.991-1.093 nm and 19.37-37.97 nm, respectively. The highest adsorption capacities for formaldehyde and iodine were 295 mg/g and 1387 mg/g, respectively. SEM images demonstrated the topographic structure of the AC.