Comprehensive Characterisation of the Morphological, Thermal and Kinetic Degradation Properties of Gluconacetobacter xylinus synthesised Bacterial Nanocellulose

Abstract

Microbial-assisted synthesis can advance nanocellulose production, while addressing the economics and environmental friendliness of conventional techniques. Bacterial nanocellulose (BNC) is a linear exopolysaccharide with 3-D structures and nanofibril networks synthesized by various bacteria. The physical, chemical and mechanical properties of BNC have been characterized for various applications. However, limited knowledge of the thermal degradation and kinetic properties of BNC currently hampers its utilization as renewable biopolymers as heat, temperature, and heating rates influence life span and future applications. Therefore, this study examines the thermal, chemical, morphological, microstructure, and kinetic properties of Gluconacetobacter xylinus synthesized BNC through thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and isoconversional Ozawa–Flynn–Wall (OFW) kinetic modeling. The SEM results showed that BNC has a highly dense fibril structure with overlapping knots, which denotes a high surface area, porosity and crystallinity, whereas EDX revealed C, O, and Na. TGA revealed BNC undergoes three-stage thermal degradation with mass loss of 53.57% and residual mass of 46.43% on average. Kinetic modeling revealed the average activation energy (Ea = 59.39 kJ/mol) and pre-exponential factor (ko = 1.62 × 1010 min−1) for BNC indicating high thermal reactivity. Thus, G. xylinus- synthesized BNC has potential for many applications in the future.

Keywords

• thermogravimetry
• kinetics
• bacterial nanocellulose
• gluconacetobacter xylinus