Freeze gelation:: a new option for the production of biological ceramic composites (biocers)

Freeze gelation was used for immobilization and conservation of living microorganisms in inorganic solids. The irreversible sol-gel transition of a mixture of colloidal silica, ceramic powder and biocomponent by freezing (freeze gelation or freeze casting) enables the production of low-cost, porous, crack-free green bodies with nearly zero shrinkage in which microorganisms are immobilized safely. First investigations to the survival rate, activity and storage ability will be presented for biocers with Bacillus sphaericus and Saccharomyces cerevisiae under the selected freeze and drying conditions. The structure of these new biocers were characterized by SEM micrographs, physical adsorption and mercury porosimetry. (C) 2002 Elsevier Science B.V. All rights reserved.