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A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal treatment, the bio-organic material is removed and the inorganic particles are sintered. The method is applicable to the fabrication of various inorganic fibers, including metals and ceramics. The route completely avoids the use of organic solvents, such as N-methyl-2-pyrrolidone, and additives associated with the currently used fiber fabrication methods. In addition, it inherently avoids the manifestation of so-called macro voids and allows the facile incorporation of additional metal oxides in the inorganic hollow fibers. [ABSTRACT FROM AUTHOR]

Theincorporation of an organic group into sol–gel-derivedsilica causes significant changes in the structure and propertiesof these materials. Therefore, the thermal treatment of organosilicamaterials may require a different approach. In the present paper,kinetic parameters (activation energy, pre-exponential constant, andreaction models) have been determined from mass loss data for thedehydration, dehydroxylation, and decomposition reactions that takeplace upon heating silica and organosilica. Parameters were obtainedby employing model-free isoconversional methods to data obtained undermultiple heating rates as well as by multivariate analysis of thekinetics using a multistep reaction model with distributed activationenergy. For silica, it can be concluded that the reaction atmosphere(i.e., inert or thermo-oxidative) has no influence on the reactionrate of the dehydration and dehydroxylation reactions that are responsiblefor the densification of the material. Under inert atmosphere, fulldehydration can be reached without affecting the organic moiety. Achievingcomplete dehydroxylation of the organosilica is practically impossibleas decomposition does manifest itself under commonly employed calcinationtemperatures. This indicates that prudence is required in designinga heat treatment program for these hybrid materials. To aid in optimizingthe thermal treatment, a predictive model was developed, which canbe used to forecast the extent of dehydration, dehydroxylation, anddecomposition reactions under a multitude of temperature programs. [ABSTRACT FROM AUTHOR]