Next to cellulose, chitin is the second most abundant biopolymer on earth, serving as building block inside the crustacean exoskeleton, insect cuticles and fungal cell walls. The structural component of fungal cell walls is comprised of nano-sized fibers made of chitin and glucan, which are covalently cross-linked. These fibers form a ready-made nanocomposite fabric, which is useful in the development of nanopapers, potentially applicable as membranes in water treatment operations. Due to their high content of N-acetyl groups not only size-exclusion filtration but also adsorption of cationically charged contaminants, such as heavy metal ions, should be feasible. In this study, the chitin-glucan base-material was extracted from common mushroom fruiting body (Agaricus bisporus). Extracts from common mushroom were found to be readily disintegrated into nanofiber dimensions (10 to 20 nm wide, several μm long) without any mechanical treatment, thus already utilizable for direct nanopaper preparation. Nanopapers were prepared by vacuum filtration of homogeneous chitin-glucan dispersions. The membrane performance of these nanopapers was assessed with respect to their permeance and rejection of contaminants both in size-exclusion and adsorption mode. Furthermore, the applicability of these nanopapers in organic solvent nanofiltration was investigated. It was found that chitin-glucan nanopapers were efficient in rejecting dissolved macromolecules from aqueous and THF solution, respectively, in the range of several thousand Daltons, corresponding to particles sizes of around 10 nm. Furthermore, adsorption of metal ions was successfully achieved due to interaction of these ions with the N-acetyl group of chitin.

Chitin-Glucan nanopapers from fungi in membrane and water treatment operations

253rd National Meeting (2017)

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