Active Carbons from Chemically Mediated Pyrolysis of Agricultural Wastes: Application in Simultaneous Removal of Binary Mixture of Benzene and Toluene from Water

Abstract

Active carbons were produced from bagasse, millet and sorghum straws by chemical activation with H3PO4. Carbon precursors with particle size of 1180 μm were used, in order to overcome difficulties caused by low density and high ash content. The influence of preparation conditions (temperature, residence time, and acid impregnation ratio) on the yield of the active carbons was examined. The impregnation ration which was controlled by varying the proportion of H3PO4 used for the activation had a strong influence on the yields of the carbons. The pyrolysis temperature was varied in the range 100-450 °C, but equilibrium yields of the active carbons were highest at 450C with optimum impregnation ratio of 13.6. The potential of the active carbons as efficient and economical means of removing mixture of aromatic hydrocarbon contaminants from water was indicated by the complete removal of objectionable odor from contaminated water samples containing 35.1348 mg/cm3 benzene and 34.8534 mg/cm3 Toluene, which are known carcinogens. Spectrophotometric determinations of the two solutes in the remediate water samples indicated slow but steady adsorption of the benzene/toluene mixture on the active carbons.