Highly-efficient solution plasma process (SPP) on cellulose particle size derived from nata de coco waste toward carboxymethylcellulose (CMC) for O/W Pickering emulsion bio-functional stabilizer

Carboxymethyl cellulose (CMC), an anionic water-soluble polysaccharide, is widely utilized in the food industry. In this study, CMC was successfully synthesized from microcrystalline cellulose (MCC) precursors, which were prepared by upgrading bacterial cellulose (BC) isolated from nata de coco food waste. BC holds significant potential as a sustainable cellulose source for CMC production, aimed at enhancing emulsifying properties. Specifically, a novel and green route—the solution plasma process (SPP)—was developed to heterogeneously degrade BC utilizing active species generated via electrical discharge plasma in a dilute acid solution. The SPP offers a straightforward approach to synthesizing nanomaterials with minimal chemical consumption and short preparation times under ambient conditions. The results demonstrated that the optimized MCC nanoparticles were obtained under 0.1 M HCl with the increase of SPP time (15, 30, 45, and 60 min) leading to degradation of the cellulose chain, hence yielding MCC with various particle sizes ranging from 995.73 to 2139.27 nm. Subsequently, these small-sized MCC particles underwent carboxymethylation via a heterogeneous reaction. The reduction in MCC particle size achieved through SPP effectively increased the content of carboxymethyl group in the resulting CMC (from 20.01% to 81.14%), leading to an enhancement of degree of substitution (DS) ranging from 0.57 to 2.25. Furthermore, the structural characteristics and properties of the CMC and CMC 3-based on MCC surfaces, including the influence of particle size and DS on the stabilization of oil-in-water (O/W) Pickering emulsions, were evaluated. The findings suggest that the synthesized CMC has strong potential to serve as a bio-functional stabilizer.