Production of various carboxylated CNCs from agricultural waste streams

Description

This work is a continuation of studies on the hydrolysis of cellulose in a gas/solid system utilizing pressurized HCl gas in a custom-built reactor [1] and preparing carboxylated cellulose nanocrystals (CNCs) from bacterial cellulose (BC) [2]. Work is based on the earlier work with dry fibers hydrolyzed to their leveling-off degree of polymerization (LODP), subsequently dispersed into CNCs [3,4]. Here, we introduce a process which uses agricultural waste streams as a raw material for CNCs. Potato fibers and beer residuals are side streams with a global production of millions of tons annually. However, these side streams of brewing industry and starch industry are lacking valuable end uses. Industrial processes, which are applied to dissolve carbohydrates for beer production and remove starch from potato, increase significantly the cellulose contents of the fibrous side streams. Hot alkali extraction of fiber residuals removes over 80 % of non-cellulose components. NaClO2/HCl hydrolysis continues cellulose purification and lowers the DP of cellulose to the level which is suitable for CNC dispersion. Thereafter, carboxylic groups are introduced on the surface of cellulose with TEMPO-oxidation. The hydrogel, which is purified by centrifugation, is finally dispersed with a microfluidizer. The properties of the CNCs from made from various agricultural side streams are subsequently compared with each other. All materials are suitable raw materials for carboxylated CNCs which still have the appearance of a hydrogel after dispersion.
References
[1] Pääkkönen et al. React. Chem. Eng. 2018, 3, 312-318
[2] Pääkkönen et al. ACS Sustainable Chem. Eng. 2019, 7, 14384-14388
[3] Kontturi et al. Angew. Chem. Int. Ed. 2016, 55, 14455-14458
[4] Lorenz et al. Faraday Discuss. 2017, 202, 315-330

Period	22 Aug 2022
Event title	American Chemical Society National Meeting & Exposition: Sustainability in a changing world
Event type	Conference
Location	Chicago, United States, IllinoisShow on map
Degree of Recognition	International