Characterization of Manihot residues and preparation of activated carbon

Rind, vascular system and pith of raw Manihot stems were studied in this work. The characterization included proximate and ultimate analysis and the determination of cellulose, hemicellulose, lignin, functional groups, acidic–basic groups, the point of zero charge, the specific surface area and the thermal behavior of each stem part. Carbonization was performed at 500 °C and 800 °C. The results indicated that the raw residues exhibit mainly acidic character in the order: rind > vascular system ≈ pith with 1.80, 1.35 and 1.35 mol kg−1 acidic groups, respectively. The carbon obtained at 500 °C of the different parts of the stem was mesoporous and the carbons obtained at 800 °C from the vascular system exhibited 61% microporosity. The raw residues presented smaller specific surface area than the carbonized samples. They removed however, 95% of the acid dye methyl orange and 50% of the basic dye methylene blue.