Permeation of solvents through disk type rice husk silica membrane modified with alkyl silylation reagents.

Rice husk silica (RHS) which was obtained with thermal treatment of rice husk has the size of approximately 10 micrometer with 4-5 nm pore. RHS can be mold to a disk type membrane. The membrane may have submicron pore originated from the space among the particles, and the nano pores of the rice husk silica (RHS pore). Even it is difficult to adjust the size of the pores, we can suggest that the membrane shows different permeability for the organic/inorganic solvents if the affinity between the surface of the pores and the permeating molecule is changed. In this study, we investigated the permeation of the typical solvents such as water, ethanol and toluene to the RHS membranes sintered at 1100 degrees C, 1150 degrees C and 1200 degrees C and modified with triethoxymethyl silane (CH3)Si(C2H5O)3, diethoxydiemethyl silane (CH3)2Si(C2H5O)2 and ethoxytriemethyl silane (CH3)3Si (C2H5O). The result showed that permeability of original membranes for water (e.g., 1100 degrees C, 2.87 x 10(-3) mol/m2 s Pa) was larger than ethanol (1100 degrees C, 5.51 x 10(-4) mol/m2 s Pa) and toluene (1100 degrees C, 3.09 x 10(-4) mol/m2 s Pa) at the sintering temperatures. For the silane modified membranes, the permeability for water decreased drastically while those for ethanol and toluene increased.