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Drying of Hierarchically Organized Porous Silica Monoliths-Comparison of Evaporative and Supercritical Drying. Gels 2023; 9:gels9010071. [PMID: 36661837 PMCID: PMC9858606 DOI: 10.3390/gels9010071] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
In this study, we present a detailed comparison between a conventional supercritical drying process and an evaporative drying technique for hierarchically organized porous silica gel monoliths. These gels are based on a model system synthesized by the aqueous sol-gel processing of an ethylene-glycol-modified silane, resulting in a cellular, macroporous, strut-based network comprising anisotropic, periodically arranged mesopores formed by microporous amorphous silica. The effect of the two drying procedures on the pore properties (specific surface area, pore volume, and pore widths) and on the shrinkage of the monolith is evaluated through a comprehensive characterization by using nitrogen physisorption, electron microscopy, and small-angle X-ray scattering. It can clearly be demonstrated that for the hierarchically organized porous solids, the evaporative drying procedure can compete without the need for surface modification with the commonly applied supercritical drying in terms of the material and textural properties, such as specific surface area and pore volume. The thus obtained materials deliver a high specific surface area and exhibit overall comparable or even improved pore characteristics to monoliths prepared by supercritical drying. Additionally, the pore properties can be tailored to some extent by adjusting the drying conditions, such as temperature.
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Lebedev A, Lovskaya D, Menshutina N. Modeling and scale-up of supercritical fluid processes. Part II: Supercritical drying of gel particles. J Supercrit Fluids 2021. [DOI: 10.1016/j.supflu.2021.105238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Forgács A, Papp V, Paul G, Marchese L, Len A, Dudás Z, Fábián I, Gurikov P, Kalmár J. Mechanism of Hydration and Hydration Induced Structural Changes of Calcium Alginate Aerogel. ACS APPLIED MATERIALS & INTERFACES 2021; 13:2997-3010. [PMID: 33401895 DOI: 10.1021/acsami.0c17012] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The most relevant properties of polysaccharide aerogels in practical applications are determined by their microstructures. Hydration has a dominant role in altering the microstructures of these hydrophilic porous materials. To understand the hydration induced structural changes of monolithic Ca-alginate aerogel, produced by drying fully cross-linked gels with supercritical CO2, the aerogel was gradually hydrated and characterized at different states of hydration by small-angle neutron scattering (SANS), liquid-state nuclear magnetic resonance (NMR) spectroscopy, and magic angle spinning (MAS) NMR spectroscopy. First, the incorporation of structural water and the formation of an extensive hydration sphere mobilize the Ca-alginate macromolecules and induce the rearrangement of the dry-state tertiary and quaternary structures. The primary fibrils of the original aerogel backbone form hydrated fibers and fascicles, resulting in the significant increase of pore size, the smoothing of the nanostructured surface, and the increase of the fractal dimension of the matrix. Because of the formation of these new superstructures in the hydrated backbone, the stiffness and the compressive strength of the aerogel significantly increase compared to its dry-state properties. Further elevation of the water content of the aerogel results in a critical hydration state. The Ca-alginate fibers of the backbone disintegrate into well-hydrated chains, which eventually form a quasi-homogeneous hydrogel-like network. Consequently, the porous structure collapses and the well-defined solid backbone ceases to exist. Even in this hydrogel-like state, the macroscopic integrity of the Ca-alginate monolith is intact. The postulated mechanism accounts for the modification of the macroscopic properties of Ca-alginate aerogel in relation to both humid and aqueous environments.
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Affiliation(s)
- Attila Forgács
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
- MTA-DE Redox and Homogeneous Catalytic Reaction Mechanisms Research Group, Egyetem tér 1, Debrecen H-4032, Hungary
| | - Vanda Papp
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
| | - Geo Paul
- Department of Science and Technological Innovation, Universitá del Piemonte Orientale, Viale T. Michel 11, 15121 Alessandria, Italy
| | - Leonardo Marchese
- Department of Science and Technological Innovation, Universitá del Piemonte Orientale, Viale T. Michel 11, 15121 Alessandria, Italy
| | - Adél Len
- Neutron Spectroscopy Department, Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest H-1121, Hungary
| | - Zoltán Dudás
- Neutron Spectroscopy Department, Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest H-1121, Hungary
| | - István Fábián
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
- MTA-DE Redox and Homogeneous Catalytic Reaction Mechanisms Research Group, Egyetem tér 1, Debrecen H-4032, Hungary
| | - Pavel Gurikov
- Laboratory for Development and Modelling of Novel Nanoporous Materials, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany
| | - József Kalmár
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
- MTA-DE Redox and Homogeneous Catalytic Reaction Mechanisms Research Group, Egyetem tér 1, Debrecen H-4032, Hungary
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Gurikov P, S. P. R, Griffin JS, Steiner SA, Smirnova I. 110th Anniversary: Solvent Exchange in the Processing of Biopolymer Aerogels: Current Status and Open Questions. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b02967] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Pavel Gurikov
- Hamburg University of Technology, Institute of Thermal Separation Processes, Eißendorfer Str. 38, 21073 Hamburg, Germany
| | - Raman S. P.
- Hamburg University of Technology, Institute of Thermal Separation Processes, Eißendorfer Str. 38, 21073 Hamburg, Germany
| | - Justin S. Griffin
- Aerogel Technologies, LLC 1 Westinghouse Plaza, D157, Boston, Massachusetts 02136, United States of America
| | - Stephen A. Steiner
- Aerogel Technologies, LLC 1 Westinghouse Plaza, D157, Boston, Massachusetts 02136, United States of America
| | - Irina Smirnova
- Hamburg University of Technology, Institute of Thermal Separation Processes, Eißendorfer Str. 38, 21073 Hamburg, Germany
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Ganesan K, Budtova T, Ratke L, Gurikov P, Baudron V, Preibisch I, Niemeyer P, Smirnova I, Milow B. Review on the Production of Polysaccharide Aerogel Particles. MATERIALS (BASEL, SWITZERLAND) 2018; 11:E2144. [PMID: 30384442 PMCID: PMC6265924 DOI: 10.3390/ma11112144] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/10/2018] [Accepted: 10/23/2018] [Indexed: 02/04/2023]
Abstract
A detailed study of the production of polysaccharide aerogel (bio-aerogel) particles from lab to pilot scale is surveyed in this article. An introduction to various droplets techniques available in the market is given and compared with the lab scale production of droplets using pipettes and syringes. An overview of the mechanisms of gelation of polysaccharide solutions together with non-solvent induced phase separation option is then discussed in the view of making wet particles. The main steps of particle recovery and solvent exchange are briefly described in order to pass through the final drying process. Various drying processes are overviewed and the importance of supercritical drying is highlighted. In addition, we present the characterization techniques to analyse the morphology and properties of the aerogels. The case studies of bio-aerogel (agar, alginate, cellulose, chitin, κ-carrageenan, pectin and starch) particles are reviewed. Potential applications of polysaccharide aerogel particles are briefly given. Finally, the conclusions summarize the prospects of the potential scale-up methods for producing bio-aerogel particles.
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Affiliation(s)
- Kathirvel Ganesan
- German Aerospace Center, Institute of Materials Research, Linder Hoehe, 51147 Cologne, Germany.
| | - Tatiana Budtova
- MINES Paris Tech, PSL Research University, Center for Materials Forming (CEMEF), UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France.
| | - Lorenz Ratke
- German Aerospace Center, Institute of Materials Research, Linder Hoehe, 51147 Cologne, Germany.
| | - Pavel Gurikov
- Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
| | - Victor Baudron
- Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
| | - Imke Preibisch
- Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
| | - Philipp Niemeyer
- German Aerospace Center, Institute of Materials Research, Linder Hoehe, 51147 Cologne, Germany.
| | - Irina Smirnova
- Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
| | - Barbara Milow
- German Aerospace Center, Institute of Materials Research, Linder Hoehe, 51147 Cologne, Germany.
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