Porous Material Prepared by Carbonizing Montmorillonite/Acriflavine Complex and Control of Porous Structure by Freeze-Drying

Abstract

A unique porous material can be prepared by carbonizing montmorillonite/acriflavine complex (MAC). Control of its porous structure was attempted by freeze-drying MAC blocks having various water content. The porous structure was changed over a wide range (pore volume: 1-3ml/g, pore radius: 40-240nm) by water content in MAC. Particle size of raw montmorillonite also caused certain effects. When pore volume increased, pore size also increased, i.e., both properties could not be controlled independently. In spite of such changes, uniform pore size distribution and characteristic card-house structure were kept. The porous structure was stable up to 1073K under nitrogen.

Synthesis of Porous Ceramics with Complex Pore Structure by Freeze‐Dry Processing

“…T HERE have been a variety of unique ceramics fabrication processes using freezing phenomena. [1][2][3][4][5][6][7][8][9][10] For example, Mahler and Bechtold 1 and Mahler 2 have reported a freeze-forming process for ceramic fibers using phase separation in a gelled aqueous poly(silicic acid). In their process, a columnar gel is surrounded and isolated in ice.…”

“…In another freeze-dry process, a solvent is eliminated directly by sublimation from solid state to gas for the synthesis of porous ceramics. 5,8,10 For example, highly oriented porous ceramics with high porosity (Ͼ90%) were obtained by controlling the freezing direction in metal-salt solutions. 10 Porous ceramics of this type are expected to be used for the following applications because of their high permeability and large surface area: particulate filters for environmental cleanup and reuse, gas or chemical sensors, bioreactors, and support materials for catalysts or absorbents.…”