3 results
Filters
Settings
Now showing1 - 3 of 3
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Natural grown aerogels from fruits, vegetables and mushrooms : processing and characterization(2022-09); ; ; ; Aerogels are highly porous materials with special properties like a high specific surface area up to 1200 m2 g-1 and low densities of approx. 0.1 g cm-3. Especially biopolymer aerogels (e.g. alginate, chitosan and cellulose) are used due to their high availability, biocompatibility and non-toxicity. The applications of these mesoporous materials are in fields of carrier matrices (food and pharma), thermal insulation and catalyst scaffolds. Biopolymer aerogel production requires a gelation step, in which the porous network is formed. Gelation is normally carried out in aqueous phase and can be induced via different methods (e.g. change of temperature, pH, addition of ions, etc.), followed by solvent exchange and supercritical drying. Fruits, vegetables, mushrooms and derived plant based food waste show internal three-dimensional pore networks formed by natural growth. Therefore, they can be converted into aerogel-like systems, without requiring a gelation step. The importance of sustainable processes in the (food) industry is growing steadily. In addition to energy efficiency and resource management, this also includes the recycling of food waste and by-products. Hence, the development of an alternative recycling method of food waste to natural grown aerogels is a promising solution to meet the economic requirements. The aim of this work is to provide an overview of different natural grown aerogels, which are produced based on their naturally aqueous state by solvent exchange with ethanol and supercritical drying at suitable conditions (40 °C and 100 bar). Furthermore, the aerogel-like morphology of supercritical dried fruits and vegetables is characterized. For this purpose, experimental investigations are performed related to the specific surface area (BET method), internal mesoporous structure (SEM pictures), density and volumetric shrinkage during the manufacturing process.Publicationtype: Conference Poster not in Proceedings177 123 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Lignin coating of Alginate aerogel particles(2022-09); ; Biopolymer aerogels are nanoporous lightweight materials with high surface area and very low density (0.15 g/cm3). The properties made them well desired in diverse applications such as insulation, catalysts, and drug delivery systems. However, one main drawback of the biopolymer aerogels is their hydrophilic surface and the open pore structure of aerogels which permits the penetration of moisture or reactive molecules into the inner part of the materials and may cause damage of the pores. The conventional approaches comprise of a subsequent modification step either by: (1) a hydrophobic post-modification of aerogel inner surfaces, or (2) an application of a protective coating to the aerogel outer surfaces. This research work investigates an alternative solution which introduces the possibility of one-step simultaneous gelation and coating of alginate aerogels using lignin as the coating material. In this study, lignin particles are mixed with the alginate solution subsequently the lignin alginate hydrogel particles are produced via dripping method in calcium chloride solution to facilitate ions-induced gelation. Thereafter, aerogel particles are evaluated in terms of particle morphology and porous structure, While the coating layer is evaluated in term of homogeneity and thickness. The preliminary results showed the formation of porous lignin layer as an outer shell of alginate aerogel particles as validated by SEM images, the addition of lignin up to 50% wt dry mass basis did not negatively influence the porous structure (Sv up to 350 m2/g). The targeted application for the developed lignin coated alginate aerogel particles is as thermal insulation material for building elements using blow in technique.Publicationtype: Conference Poster not in Proceedings102 118 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Scale-up of aerogel manufacturing plant for industrial production(2022-09-29); ; ; ; The special characteristics of aerogels in terms of lightweight, porous and super-insulation recommends their application in the area of building and construction. The definition of super-insulation states better insulation behavior than air. The thermal conductivity of conventional insulation products such as EPS or mineral wool are typically in the range of 30-50 mW/(m⋅K). In comparison, silica aerogels are characterized by a thermal conductivity of 12-20 mW/(m⋅K) and cellulose aerogels by a thermal conductivity of 15-20 mW/(m⋅K). This low thermal conductivity, which results from the interplay of air-filled pores and skeletal backbone, enables a more efficient and flexible application as insulation material for nearly zero energy buildings (nZEB). The limiting factor for the actual application of aerogels in an industrial scale, is currently the aerogel production. Furthermore, the supply chains of aerogels are not yet established enough to enable widespread market application. Within this work, a scale-up of the aerogel production line is performed to reduce production costs for broader market uptake. The overall scale-up includes the scale-up of each manufacturing step: gelation, solvent exchange, and supercritical drying. With this, a production capability of 50 lt. of solvent exchanged particles per day and up to 2000 lt. aerogels per year are aimed. This involves a large-scale gelation and solvent exchange plant, as well as the utilization of a 64 L autoclave for the supercritical drying step with integrated software for an automated drying. In addition to the scale-up of the manufacturing plant, different approaches to applying aerogels in insulation materials are considered in this work. A key point is the development of carbon fiber reinforced textile concrete (TRC) with a sandwich core made of Cellular Lightweight Concrete (CLCi) including silica or cellulose aerogels.Publicationtype: Conference Poster not in Proceedings451 267