Preparation of Porous Ceramics from Rice Husk Containing Al or Al{sub}2O{sub}3 Particles for Bioreactor

摘要

The porous ceramics were prepared using rice husk (RH) mixed with aluminum (Al) or aluminum oxide (Al{sub}2O{sub}3) particles in a molar ratio of 5:1 for SiO{sub}2/Al{sub}2O{sub}3. The mixed powders were formed by uniaxial pressing and sintered at 1300°C for 1h. All resulting porous ceramics had practical strength. The bulk densities of RH/Al porous ceramics (RH/Al) and RH/ Al{sub}2O{sub}3 porous ceramics (RH/Al{sub}2O{sub}3) were 0.77 and 0.90 g/cm{sup}3, respectively. According to XRD analysis, RH/Al consisted of α-Al{sub}2O{sub}3, cristobalite and mullite, and RH/Al{sub}2O{sub}3 consisted of α-Al{sub}2O{sub}3 and cristobalite. The mode pore diameters were 28 μm (RH/Al) and 94μm (RH/Al{sub}2O{sub}3). After the nitrobacteria were immobilized to porous ceramics, the decomposition rates of NH{sub}4{sup}+ at pH=6 to 8 were measured by spectroscopy. The decomposition rates of NH{sub}4{sup}+ were 1.3×10{sup}(-2) ppm/h (RH/Al) and 0.7×10{sup}(-2) ppm/h (RH/Al{sub}2O{sub}3). It suggests that both the immobilization of nitrobacteria and the decomposition rate of NH{sub}4{sup}+ depend on the surface potential of porous ceramics.