# Cellulose Nanofibrils from Black Wattle (Acacia mearnsii De Wild.) Residues Produced by High-Intensity Ultrasonication: Production and Characterization

## TL;DR

The paper shows how cellulose nanofibrils can be made from black wattle bark using ultrasound, offering an eco-friendly alternative to traditional methods.

## Contribution

The novel contribution is using high-intensity ultrasonication on black wattle residues to produce cellulose nanofibrils with specific properties.

## Key findings

- CNF with a diameter of 11.93 ± 4.83 nm was successfully produced from 1 wt% CMF suspension at 25 °C.
- The CNF showed a crystallinity index of 52.21% and thermal behavior typical of lignocellulosic nanomaterials.
- Black wattle bark residues are confirmed as a viable and sustainable source for CNF production.

## Abstract

This study investigates the production of cellulose nanofibrils
(CNF) from black wattle bark residues using high-intensity ultrasound
(HIUS) as an environmentally friendly mechanical process. The residues
were subjected to alkaline delignification and bleaching to obtain
cellulose microfibers (CMF), which were subsequently ultrasonicated
at different concentrations (1 and 2 wt %) and temperatures (4 and
25 °C). The resulting CNF suspension was characterized by atomic
force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR),
X-ray diffractometry (XRD), and thermogravimetric analysis (TGA).
Only the 1 wt % CMF suspension treated at 25 °C exhibited effective
fibrillation, yielding CNF with a diameter of 11.93 ± 4.83 nm.
The CNF displayed characteristic functional groups, a crystallinity
index of 52.21%, and thermal behavior consistent with that of lignocellulosic-derived
nanomaterials. These findings confirm the suitability of black wattle
bark residues as precursors for CNF production. Furthermore, utilizing
these residues as a raw material represents a promising alternative
to conventional cellulose sources, providing a more environmentally
sustainable route for obtaining nanofibrils through an eco-friendly
ultrasonication-based methodology.