Preparation of carbon black from rice husk by hydrolysis, carbonization and pyrolysis

Carbon black is a form of amorphous carbon that is produced by incomplete combustion of petroleum- or some plant-derived materials and has a number of industrial uses. A process consisting of hydrolysis, carbonization and pyrolysis of rice husk was developed. Under optimal hydrolysis conditions (72 wt.% sulfuric acid, 50°C, 10 min), a hydrolysis ratio of 52.72% was achieved. After carbonization of the hydrolysis solution by water bath, the solid carbon was further pyrolyzed. As the pyrolysis temperature was increased from 400 to 800°C, the carbon content increased from 83.41% to 94.66%, the number of O-H, C-H, CO, and CC surface functional groups decreased, and based on Brunauer-Emmett-Teller (BET) results, the specific surface area and pore volume of carbon black increased from 389 to 1,034 m(2)/g and from 0.258 to 0.487 cm(3)/g, respectively. X-ray diffraction pattern (XRD) and Raman spectroscopy analyses of samples pyrolyzed at 400-800°C showed a localized graphitic structure. It is possible that the hydrolysis/carbonization/pyrolysis process developed in this study could also be applicable to the preparation of carbon black from other types of biomass.