Evaluation of chitosan aerogel for application in aeronautics

Abstract

The traditional way of CO2 removal from aircraft cabins via dilution is considered as an outdated technology due to negative economic and environmental impact. Developments in nanostructured chitosan aerogels for selective CO2 adsorption open up new perspectives for climate control strategies. Considering industrial requirements in terms of productivity and throughput the JetCutter technology was used right from the beginning of development. Chitosan bead generation was performed at bench scale with throughput rates of 75+ kg/h. After regeneration of the chitosan gel beads chemical functionalization was performed by grafting polyethyleneimine (PEI) and phenylenediamine (PDA) onto the nanostructured gel backbone. Established drying with super critical CO2 was used to produce materials of pronounced mesoporosity. Functionalized chitosan aerogel beads were characterized according to aerogel standards. In addition dynamic breakthrough measurements were performed with an atmosphere of 2500 ppm CO2 in nitrogen. Scanning electron microscopy revealed homogeneous and expanded three dimensional interconnected fibrillary nanostructures. Pore size distributions and specific surface areas matched typical values for chitosan aerogels. Optical image analysis gave monodisperse particle size distribution. Packing densities were calculated to be above 65 %. Fourier transform infrared spectrometry performed on different stages during functionalization proved successful linkage between chitosan and PEI/PDA. Within the presentation requirements for onboard environmental control systems (ECS) and possible benefits from using aerogel filter materials will be explained. Also results of dynamic breakthrough measurements with binary gas mixtures and results from static physisorption experiments will be compared. Different pretreatments and their consequences for application in aeronautics will be discussed as well as competing materials already used in ECS onboard the International Space Station. This work is part of the project Advanced Technology Long-range Aircraft-concepts (ATLAs) and receives funding from the aeronautics research program of the German Aerospace Center.