Shortened aerogel fabrication times using an ethanol–water azeotrope as a gelation and drying solvent

2015 ◽  
Vol 3 (2) ◽  
pp. 762-772 ◽  
Author(s):  
L. S. White ◽  
M. F. Bertino ◽  
G. Kitchen ◽  
J. Young ◽  
C. Newton ◽  
...  
Keyword(s):  
Supercritical Drying ◽  
Solvent Exchange ◽  
Water Azeotrope

Native and cross-linked aerogel monoliths were fabricated in a few hours using a technique that does not require solvent exchange prior to supercritical drying.

scholarly journals Towards Porous Silicon Oxycarbide Materials: Effects of Solvents on Microstructural Features of Poly(methylhydrosiloxane)/Divynilbenzene Aerogels

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2589 ◽  
Author(s):  
Susana Aguirre-Medel ◽  
Prasanta Jana ◽  
Peter Kroll ◽  
Gian Sorarù
Keyword(s):  
Porous Silicon ◽  
Pore Formation ◽  
Supercritical Drying ◽  
Silicon Oxycarbide ◽  
Cross Linking ◽  
Solvent Exchange ◽  
Hydrosilylation Reaction ◽  
Liquid Co2 ◽  
Major Factors ◽  
The Impact

We investigate the impact of solvents on the microstructure of poly(methylhydrosiloxane)/divinylbenzene (PMHS/DVB) aerogels. The gels are obtained in highly diluted conditions via hydrosilylation reaction of PMHS bearing Si-H groups and cross-linking it with C=C groups of DVB. Polymer aerogels are obtained after solvent exchange with liquid CO2 and subsequent supercritical drying. Samples are characterized using microscopy and porosimetry. Common pore-formation concepts do not provide a solid rationale for the observed data. We postulate that solubility and swelling of the cross-linked polymer in various solvents are major factors governing pore formation of these PMHS/DVB polymer aerogels.

scholarly journals Ultralight-Weight Cellulose Aerogels from NBnMO-Stabilized Lyocell Dopes

2007 ◽  
Vol 2007 ◽  
pp. 1-4 ◽  
Author(s):  
Falk Liebner ◽  
Antje Potthast ◽  
Thomas Rosenau ◽  
Emmerich Haimer ◽  
Martin Wendland
Keyword(s):  
Carbon Dioxide ◽  
Solid State ◽  
Solution Structure ◽  
Supercritical Drying ◽  
Regenerated Cellulose ◽  
Cellulose Content ◽  
Solvent Exchange ◽  
New Materials ◽  
Specific Density ◽  
Regeneration Procedure

Cellulose aerogels are intriguing new materials produced by supercritical drying of regenerated cellulose obtained by solvent exchange of solid Lyocell moldings. FromN-methylmorpholine-N-oxide solutions with cellulose contents between 1 and 12%, dimensionally stable cellulose bodies are produced, in which the solution structure of the cellulose is largely preserved and transferred into the solid state. The specific density and surface of the obtained aerogels range from 0.05 to 0.26 g/cm3and from 172 to 284m2/g, respectively, depending on the cellulose content of the Lyocell dopes and regeneration procedure. A reliable extraction and drying procedure using supercritical carbon dioxide, the advantageous use of NBnMO as stabilizer for the Lyocell dopes, and selected physical properties of the materials is communicated.

Super Thermal Insulating SiO2 Cryogels Prepared by Vacuum Freeze Drying

2010 ◽  
Vol 105-106 ◽  
pp. 851-854 ◽  
Author(s):  
Li Fen Su ◽  
Lei Miao ◽  
Gang Xu ◽  
Sakae Tanemura
Keyword(s):  
Freeze Drying ◽  
Ambient Pressure ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
Base Catalysis ◽  
Low Density ◽  
Solvent Exchange ◽  
Acid Base ◽  
Thermal Insulating ◽  
Silica Precursor

Traditionally, silica aerogels with low thermal conductivity are prepared by supercritical drying, however, the process is expensive and hazardous due to it run in autoclaves. In order to overcome these disadvantages, a cheaper and safer process, drying at ambient pressure has been developed for decades, but tedious repetitive gel washing and solvent exchange steps are involved. Therefore, in the present study, a novel vacuum freeze-drying was utilized to prepare the super thermal insulating SiO2 cryogels. The wet gels were synthesized via acid-base catalysis using tetraethoxysilane (TEOS) as a silica precursor and ethanol as a solvent. After vacuum freeze drying, nanoporous SiO2 cryogels with low density in the range of 0.08-0.15 g/cm3 were obtained.

scholarly journals Investigation of Aerogel Production Processes: Solvent Exchange under High Pressure Combined with Supercritical Drying in One Apparatus

Gels ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 4
Author(s):  
Artem Lebedev ◽  
Ekaterina Suslova ◽  
Aleksander Troyankin ◽  
Daria Lovskaya
Keyword(s):  
Carbon Dioxide ◽  
Phase Diagram ◽  
Experimental Study ◽  
Supercritical Drying ◽  
Solvent Exchange ◽  
Efficient Technology ◽  
Production Processes ◽  
Improve Production Technology ◽  
Homogeneous Regions ◽  
Organic Aerogels

This work aims to contribute to the theoretical and experimental research of supercritical processes for intensification and combination in one apparatus. Investigation is carried out to improve production technology of organic alginate aerogels. It is proposed within the investigation to carry out the solvent exchange stage, an important stage of organic aerogels production, under pressure in a carbon dioxide medium in the same apparatus used for supercritical drying. The phase behavior in the system “carbon dioxide–water–2-propanol”, which arises during such a solvent exchange stage, is studied theoretically. An experimental study of the process of step-by-step solvent exchange under pressure was carried out through multiphase and homogeneous regions of the phase diagram of such a system. As a result, new highly efficient technology for the production of organic aerogels was proposed, which can be implemented by combining the two main stages of the process.

scholarly journals Improvement of Solvent Exchange for Supercritical Dried Aerogels

2021 ◽  
Vol 8 ◽  
Author(s):  
Marina Schwan ◽  
Sarah Nefzger ◽  
Behdad Zoghi ◽  
Christina Oligschleger ◽  
Barbara Milow
Keyword(s):  
Carbon Dioxide ◽  
Solvent Extraction ◽  
Process Parameters ◽  
Supercritical Drying ◽  
Peristaltic Pump ◽  
Solvent Exchange ◽  
Karl Fischer Titration ◽  
Surface Areas ◽  
Organic Aerogels ◽  
Suitable System

The solvent exchange as one of the most important steps during the manufacturing process of organic aerogels was investigated. This step is crucial as a preparatory step for the supercritical drying, since the pore solvent must be soluble in supercritical carbon dioxide to enable solvent extraction. The development and subsequent optimization of a suitable system with a peristaltic pump for automatic solvent exchange proved to be a suitable approach. In addition, the influence of zeolites on the acceleration of the process was found to be beneficial. To investigate the process, the water content in acetone was determined at different times using Karl Fischer titration. The shrinkage, densities, as well as the surface areas of the aerogels were analyzed. Based on these, the influence of various process parameters on the final structure of the obtained aerogels was investigated and evaluated. Modeling on diffusion in porous materials completes this study.

scholarly journals Polysaccharide-Based Aerogel Bead Production via Jet Cutting Method

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1287 ◽  
Author(s):  
Imke Preibisch ◽  
Philipp Niemeyer ◽  
Yusuf Yusufoglu ◽  
Pavel Gurikov ◽  
Barbara Milow ◽  
...  
Keyword(s):  
Particle Production ◽  
Scale Up ◽  
Supercritical Drying ◽  
Absorption Capacity ◽  
Diffusion Method ◽  
Size Distributions ◽  
Solvent Exchange ◽  
Particle Size Distributions ◽  
Cutting Method ◽  
Ph Adjustment

The aim of this work is to develop a method to produce spherical biopolymer-based aerogel particles, which is capable for scale-up in the future. Therefore, the jet cutting method is suggested. Amidated pectin, sodium alginate, and chitosan are used as a precursor (a 1–3 wt. % solution) for particle production via jet cutting. Gelation is realized via two methods: the internal setting method (using calcium carbonate particles as cross-linkers and citric and acidic acid for pH adjustment) and the diffusion method (in calcium chloride solutions). Gel particles are subjected to solvent exchange to ethanol and consequent supercritical drying with CO2. Spherical aerogel particles with narrow particle size distributions in the range of 400 to 1500 µm and a specific surface area of around 500 m2/g are produced. Overall, it can be concluded that the jet cutting method is suitable for aerogel particle production, although the shape of the particles is not perfectly spherical in all cases. However, parameter adjustment might lead to even better shaped particles in further work. Moreover, the biopolymer-based aerogel particles synthesized in this study are tested as humidity absorbers in drying units for home appliances, particularly for dishwashers. It has been shown that for several cycles of absorption and desorption of humidity, aerogel particles are stable with an absorption capacity of around 20 wt. %.

Cellulose aerogels: Highly porous, ultra-lightweight materials

Holzforschung ◽  
2008 ◽  
Vol 62 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Falk Liebner ◽  
Antje Potthast ◽  
Thomas Rosenau ◽  
Emmerich Haimer ◽  
Martin Wendland
Keyword(s):  
Carbon Dioxide ◽  
Solid State ◽  
Solution Structure ◽  
Supercritical Drying ◽  
Regenerated Cellulose ◽  
Solvent Exchange ◽  
New Materials ◽  
Surface Areas ◽  
Degradation Reactions ◽  
Highly Porous

Abstract Cellulosic aerogels are intriguing new materials produced by supercritical drying of regenerated cellulose obtained by solvent exchange of solid Lyocell moldings. From N-methylmorpholine-N-oxide (NMMO) solutions with cellulose contents between 1 and 12%, dimensionally stable cellulose bodies are produced, in which the solution structure of the cellulose is largely preserved and transferred into the solid state, the material having densities down to 0.05 g cm-3 and surface areas of up to 280 m2 g-1. In this study, several aspects of cellulosic aerogel production are communicated: the stabilization of the cellulose solutions against degradation reactions by agents suitable for later extraction and drying, a reliable extraction and drying procedure by supercritical carbon dioxide, the advantages of DMSO/NMMO in this procedure as a solvent/non-solvent pair, and some data on the physical properties of the materials.

scholarly journals Biopolymer-Based Aerogel Bead Production via Jet Cutting Method

2018 ◽  
Author(s):  
Imke Preibisch ◽  
Philipp Niemeyer ◽  
Yusuf Yusufoglu ◽  
Pavel Gurikov ◽  
Barbara Milow ◽  
...  
Keyword(s):  
Particle Production ◽  
Scale Up ◽  
Supercritical Drying ◽  
Absorption Capacity ◽  
Narrow Particle Size Distribution ◽  
Diffusion Method ◽  
Solvent Exchange ◽  
Cutting Method ◽  
Cross Linker ◽  
And Diffusion

The aim of this work is to develop a method to produce spherical biopolymer-based aerogel particles, which is capable for scale up in the future. Therefore, jet cutting method is suggested. Amidated pectin and sodium alginate were used as precursor (1–3 wt. % solution) for particle production via jet cutting. Gelation was realized via two methods: internal setting method (using calcium carbonate particles as cross-linker and citric and acidic acid for pH adjustment) and diffusion method (in calcium chloride solutions). Gel particles were subjected to solvent exchange to ethanol and consequent supercritical drying with CO2. Spherical aerogel particles with narrow particle size distribution in the range of 400 to 1500 µm and with specific surface area of around 500 m2/g could be produced. Overall, it can be concluded that jet cutting method is suitable for aerogel particle production, although the shape of the particles is not perfectly spherical in all cases. However, parameter adjustment might lead to even better shaped particles in further work. Moreover, the biopolymer-based aerogel particles synthesized in this study were tested as humidity absorber in drying units for home appliances, particularly for dishwashers. It could be shown that for several cycles of absorption and desorption of humidity aerogel particles are stable with an absorption capacity of around 20 wt. %.

scholarly journals Gellan aerogel production applying supercritical technology

2019 ◽  
Author(s):  
Gabriela Fujita de Freitas ◽  
Julian Martinez ◽  
Juliane Viganó
Keyword(s):  
Carbon Dioxide ◽  
High Surface ◽  
High Surface Area ◽  
Supercritical Drying ◽  
Gelling Agent ◽  
Diffusion Method ◽  
Low Density ◽  
Solvent Exchange ◽  
Hydrogel Formulation ◽  
Pre Treatment

Aerogels are materials with an open porous, low density and high surface area, which make them an interesting material to carry target compounds. The proposal of this work was to produce gellan aerogels and to study the effect of the diffusion method and internal setting method, the temperature of the gellan pre-treatment, and the addition of inulin on the aerogel shrinkage during the process. The aerogels were produced through hydrogel formulation, solvent exchange to obtain alcogel, and supercritical drying with carbon dioxide. The addition of inulin has reduced the shrinkage, but gelling methods to avoid the inulin loss must be studied, as the oil containing the gelling agent.

Sign in / Sign up

Export Citation Format

Share Document