Integrated process for production of bio-based aerogels
Final Report Abstract
Aerogels are extremely porous materials having the pore size distribution mainly in the mesopore range (2-50 nm). A number of different organic precursors (polysaccharides, biopolymers) can be utilized to produce aerogels from sustainable sources and with specific functions, which can be successfully used in other emerging areas besides thermal insulation (adsorption, life science applications). The main objective of the present proposal is to investigate the mechanisms resulting in the accelerated solvent exchange and gelation process in organic gels in presence of carbon dioxide at elevated pressure, which results in the aerogels with unusual textural properties and very low thermal conductivity. The understanding of these mechanisms should enable the integration of the fast solvent exchange under pressure (HPSE) and CO2 induced gelation into the production of the bio-based organic gels and lead to the substantial reduction of the overall process time. We found that the CO2 induces gelation technique works for many biopolymers and hybrid systems providing aerogels with excellent textural properties. Furthermore, we established the solvent selection frameworks evaluating the influence of biopolymer choice, solvent choice and solvent exchange procedure for evaluating the kinetics for the solvent exchange process. In addition, we established the thermodynamic basis for the integration of gelation, solvent exchange and drying steps under CO2 medium. We realized that the Integration of CO2 induced gelation, solvent exchange and supercritical drying is a promising approach for production of many aerogels. Furthermore, our observations on the solvent removal during the pressurization step of the supercritical drying was another important milestone in reducing the costs of the aerogel production. Both processes are further developed in cooperation with industry. The understanding of the aerogel production process developed in this project is now the stepping-stone for the continuous production of aerogels. The CO2 induced gelation technique can be used for several applications ranging from thermal insulation, wound care, drug delivery and nutrition applications. The results generated here provided one basis of investigation in a DFG priority program. The success of this project is demonstrable through further cooperation and partnerships established with industry, new national consortiums and new inter university research collaborations. The highlights of the work are communicated through 6 publications in peer-reviewed journals and 8 conference proceedings.
Publications
- Hybrid alginate based aerogels by carbon dioxide induced gelation: Novel technique for multiple applications, J. Supercrit. Fluids 2015, 106, 23-33
S.P. Raman, P. Gurikov, I. Smirnova
(See online at https://doi.org/10.1016/j.supflu.2015.05.003) - On the Road to Biopolymer Aerogels—Dealing with the Solvent, Gels 2015, 1, 291-313
S.P. Raman, P. Gurikov, P. Dieringer, M. Sun, I. Smirnova
(See online at https://doi.org/10.3390/gels1020291) - Preparation of Biopolymer Aerogels Using Green Solvents, J. Vis. Exp. 2016, (113), e54116
S.P. Raman, P. Gurikov, I. Meissner, I. Smirnova
(See online at https://doi.org/10.3791/54116) - Mesoporous guar galactomannan based biocomposite aerogels through enzymatic crosslinking Composites, Part A 2017, 94, 93-103
A. Ghafar, P. Gurikov, S.P. Raman, K. Parikka, M. Tenkanen, I. Smirnova, K. Mikkonen
(See online at https://doi.org/10.1016/j.compositesa.2016.12.013) - First Evidence of Solvent Spillage under Subcritical Conditions in Aerogel Production, Ind. Eng. Chem. Res., 2018, 57 (26), pp 8698–8707
A. Bueno, I. Selmer, S.P. Raman, P. Gurikov, W. Lölsberg, D. Weinrich, M. Fricke, and I. Smirnova
(See online at https://doi.org/10.1021/acs.iecr.8b00855) - Alginate aerogels carrying calcium, zinc and silver cations for wound care: Fabrication and metal detection, J. Supercrit. Fluids 2019, 153, 104545
S.P. Raman, C. Keil, P. Dieringer, C. Hübner, A. Bueno, P. Gurikov, J. Nissen, M. Holtkamp, U. Karst, H. Haase and I. Smirnova
(See online at https://doi.org/10.1016/j.supflu.2019,104545)
