Controllable conversion of cellulose nanocrystals to cellulose microspheres: Insight on the effect of parameters during spray drying, TAPPI Journal February 2025

Application: This paper focuses on the controlled preparation of cellulose microspheres. The morphology and structure of cellulose microspheres were regulated by controlling the size of CNCs, the concentration of CNCs, and the inlet temperature of spray drying, providing a wider application potential for cellulose.

Author: Qingjun Mengh, Wenliang Zheng, and Yang Xu

ABSTRACT: Cellulose microspheres, which have mainly been produced via the sol-gel method up until now, exhibit a promising potential for broad applications due to their regular microstructure and renewability. However, some issues with production of cellulose microspheres, such as the recycling of involved organic solvents and the removal of the residual solvents, should be solved. In this study, a cellulose nanocrystals (CNCs) suspension was used to produce cellulose microspheres via spray drying in order to avoid the use of organic solvents. The effects of CNCs particle size, CNCs concentration, and inlet temperature of spray drying on microstructure and particle size of cellulose microspheres were investigated. The results indicated that the optimal average particle size and concentration of CNCs used for obtaining cellulose microspheres were 106 nm and 0.1 wt%, respectively. Under the optimal conditions, cellulose microspheres with a regular spherical morphology and an average particle size of ca. 3 ìm were obtained. The sulfuric acid hydrolysis and spray drying process barely affected the crystalline structure of cellulose. However, the introduced sulfhydryl groups, which were confirmed by Fourier transform infrared spectroscopy results, degraded the thermostability of cellulose. Generally speaking, converting CNCs to cellulose microspheres via spray drying is beneficial for promoting the controllable and continuous production of cellulose microspheres.