Continuous production of cellulose microbeads by rotary jet atomization

The replacement of plastic microbeads with biodegradable alternatives is essential due to the environmental persistence of plastics and their accumulation within the human food chain. Hypothesis: Cellulose microbeads could be such alternative, but their production is hindered by the high viscosity of cellulose solutions. It is expected that this viscosity can be harnessed to induce filament thinning of jets of cellulose solutions to create droplets with diameters within the micrometre range, which can then be converted to solid cellulose microbeads via phase inversion. Experiments: A 3D printed rotating multi-nozzle system was used to generate jets of cellulose dissolved in solutions of [EMIm][OAc] and DMSO. The jets were subject to Rayleigh breakup to generate droplets which were captured in an ethanol anti-solvent bath, initiating phase-inversion, and resulting in regeneration of the cellulose into beads. Findings: Control of both process (e.g. nozzle dimensions) and operational (e.g. rotational speed and pressure) parameters has allowed suppression of both satellite droplets generation and secondary droplet break-up, and tuning of the filament thinning process. This resulted in the continuous fabrication of cellulose microbeads in the size range 40-500 mu m with narrow size distributions. This method can produce beads in size ranges not attainable by existing technologies. (C) 2022 The Authors. Published by Elsevier Inc.

Automated summary

The replacement of plastic microbeads with biodegradable alternatives is crucial in order to address the environmental persistence of plastics and their accumulation within the human food chain. This study explores the use of cellulose microbeads as a potential alternative, overcoming the challenges posed by the high viscosity of cellulose solutions. Through a 3D-printed rotating multi-nozzle system, cellulose jets were generated and subjected to controlled processes to create and regulate droplet sizes within the micrometre range, resulting in the continuous fabrication of cellulose microbeads with narrow size distributions in the range of 40-500 μm. This innovative method offers the production of microbeads in size ranges that were not previously achievable using existing technologies.