Effect of two-stage process on the preparation and characterization of porous carbon composite from rice husk by phosphoric acid activation

Activated carbon composite prepared from rice husk using phosphoric acid activation has been studied through precarbonization of the precursor followed by chemical activation. This method can produce carbons with micro- and mesoporous structure. The ratio of chemical activating agent to precarbonized carbon was fixed at 4.2. The surface area, pore volume, and pore size distribution of carbon composite samples activated at three different temperatures (700, 800, and 900 degreesC) were measured using nitrogen adsorption isotherms at 77 K. The pore-opening and pore-widening effects occurred simultaneously during the process, as evidenced by scanning electron micrographs. The X-ray diffraction curve revealed the evolution of crystallites of carbon and silica during activation at higher temperature. The FTIR spectrum also provided evidence for the presence of silica in the carbon composite. The proper choice of the preparation conditions had an influence on the micropore and mesopore volumes of the activated carbon composite, which were 0.1187 and 0.2684 cm(3)/g, respectively. The production yield was observed to decrease with increasing activation temperature.