Structure and properties of a moulded carbon derived from rice hull

Abstract

Rice hull was moulded into a tube (outer diameter: 54 mm; inner diameter: 17 mm, length: c. 170 mm) by use of an extruder and then carbonized in nitrogen atmosphere below 1000 °C. Ash content of the hull was 16 wt%, of which c. 94 and 4 wt% were SiO₂ and K₂O, respectively. Carbon yield and shrinkage of the mould after carbonization at 1000 °C were 42 wt%, and 43 vol%, respectively. The bulk density increased with rising of carbonization temperature to reach to 0.93 g ml⁻¹ at 1000 °C via 0.82 g ml⁻¹ at 500 °C. The largest compressive strength of 3.6 MPa was obtained after carbonization at 1000 °C. No micropore was developed after carbonization, and the total pore volume measured by a mercury porosimeter was 0.25–0.31 ml g⁻¹ after carbonization. These data were compared with those of charcoal.