Vibration-Assisted Fluidization of Nanocellulose

Abstract

Nanocellulose, a renewable nanomaterial prized for its mechanical strength, biocompatibility, and tunable properties, faces challenges in gas-solid fluidization due to nanoparticle agglomeration, weak gas-solid interactions, and high elutriation caused by strong interparticle forces. This study uses pressure fluctuation analysis across frequency and time-frequency (wavelet transform) domains to investigate nanocellulose fluidization in a gas-solid bed. Mechanical vibration was introduced to optimize fluidization, with effects compared against nonvibrated conditions. Results show vibration significantly reduces agglomerate size and enhances bed expansion, improving fluidization efficiency. Notably, vibration lowers the minimum gas velocity requirement by approximately 4-fold. Pressure fluctuation analysis reveals that vibration amplifies low-frequency energy, fostering smaller bubbles and shifting energy contributions from large agglomerates to finer hydrodynamic structures. This shift correlates with intensified agglomerate interactions, leading to breakup and size reduction. Finally, the effect of introducing a powder additive to the nanocellulose bed on the hydrodynamics was examined, showing a moderate rise in macroscale energy at 1 % additive loading and a pronounced shift at 2 %, where macro structures accounted for nearly 45 % of the spectral energy. Overall, these findings underscore vibration-assisted fluidization as a promising method for scalable nanocellulose processing, offering actionable insights for advancing industrial applications.