• Kronlund, Dennis
• Willför, Stefan
• Sundberg, Anna
• Xu, Wen Yang
• Liu, Jun
• Backman, Peter
• Xu, Chunlin
• Bin, Li
• Peltonen, Jouko
• Grénman, Henrik

Abstract

The traditional method to isolate cellulose nanocrystals (CNCs) is tosubject cellulosic materials to strong acid hydrolysis by mineral acids,which usually causes problems such as corrosion of equipment, the needfor large amounts of water, the difficulty of acid recovery, andover-degradation of cellulose. Thus, a green and sustainable approachfor the preparation of CNCs was developed where mild acid hydrolysiswith diluted oxalic acid was used. The reaction kinetics of differentpreparation parameters, such as reaction temperature, oxalic acid dose,addition of HCl, and reaction time were thoroughly investigated. A highyield of up to 85 % was achieved by mild oxalic acid hydrolysis incomparison to the yield of 35 % using the most common approach withsulfuric acid hydrolysis. The CNCs from the above approach have a highthermal stability, that is, a maximum thermal degradation temperature of350 °C in comparison to 200 °C when sulfuric acid hydrolysis was used.Importantly, oxalic acid solutions were readily recovered, and exhibitedconsistently high performance in several continuous runs of reaction.The hydrolysates contained mostly monomeric sugars, which could befurther utilized for chemical or biofuel production.

Topics

• impedance spectroscopy
• mineral
• corrosion
• cellulose
• degradation temperature