Ultrasonic Irradiation Coupled with Microwave Treatment for Eco-friendly Process of Isolating Bacterial Cellulose Nanocrystals

Abstract

The isolation of crystalline regions from fibers cellulose via the hydrolysis route generally requires corrosive chemicals, high-energy demands, and long reaction times, resulting in high economic costs and environmental impact. From this basis, this work seeks to develop environment-friendly processes for the production of Bacterial Cellulose Nanocrystals (BC-NC). To overcome the aforementioned issues, this study proposes a fast, highly-efficient and eco-friendly method for the isolation of cellulose nanocrystals from Bacterial Cellulose, BC. A two-step processes is considered: (1) partial depolymerization of Bacterial Cellulose (DP-BC) under ultrasonic conditions; (2) extraction of crystalline regions (BC-NC) by treatment with diluted HCl catalyzed by metal chlorides (MnCl2 and FeCl3.6H2O) under microwave irradiation. The effect of ultrasonic time and reactant and catalyst concentrations on the index crystallinity (CrI), chemical structure, thermal properties, and surface morphology of DP-BC and BC-NC were evaluated. The results indicated that the ultrasonic treatment induced depolymerization of BC characterized by an increase of the CrI. The microwave assisted by MnCl2-catalyzed mild acid hydrolysis enhanced the removal of the amorphous regions, yielding BC-NC. A chemical structure analysis demonstrated that the chemical structures of DP-BC and BC-NC remained unchanged after the ultrasonic treatment and MnCl2-catalyzed acid hydrolysis process.

Nanocellulose: From Fundamentals to Advanced Applications

“…Filter paper and microcrystalline cellulose Solution plasma-chemical processing as an oxidation-hydrolysis strategy Surov et al, 2018 Cotton linters Single step ammonium persulfate-assisted swelling, followed by oxidation Wang et al, 2019 Cellulose fibers Ball mill assisted fully recyclable solid acid hydrolysis Song et al, 2018 Broomcorn Stalks Acid hydrolysis followed by sonication Langari et al, 2019 Eucalyptus hardwood Irradiation oxidation and organosolv solubilization Zhang and Liu, 2018 Microcrystalline cellulose Ultrasonic pretreatment in ionic liquid followed by acid hydrolysis Pang et al, 2018 Nata de coco Ultrasonic irradiation coupled with microwave treatment Wardhono et al, 2018 Oil palm Sono-assisted TEMPO oxidation Rohaizu and Wanrosli, 2017 Wood sawdust Sono-chemical synthesis using acid hydrolysis Shaheen and Emam, 2018 Microcrystalline cellulose Recyclable citric/hydrochloric acids Yu et al, 2019 Commercial microcrystalline cellulose…”

Enzymatic Hydrolysis of Bacterial Cellulose for the Production of Nanocrystals for the Food Packaging Industry

“…The phase contrast signal, arising from the power dissipated by the tip, is sensitive to the material stiffness, allowing the easier detection of nanosized structures that could be difficult to recognize in the corresponding height images [14]. These shapes differ greatly from the typical needle-like shape of BCNCs obtained by both acid hydrolysis [15] and enzymatic hydrolysis [12]. Although not common, the rod-like and ellipsoidal/spherical shapes have already been described in the context of cellulose nanoparticles.…”

Calorimetry Technique for Observing the Evolution of Dispersed Droplets of Concentrated Water-in-Oil (W/O) Emulsion during Preparation, Storage and Destabilization

“…By observing the difference in energy flow between the sample and reference, the thermal properties of materials can be measured [18]. DSC is widely used for the decomposition behavior determination of the polymer [19][20][21][22]. In the emulsion system, DSC monitors the solidification process inside the droplets and calculates the temperature dependence of the nucleation rate [23].…”