# Valorisation of Barley Straw for Sustainable Nanocellulose Production via Subcritical Alkaline Hydrolysis and HDES-Assisted Processing

## TL;DR

This paper presents a sustainable method to produce nanocellulose from barley straw using subcritical alkaline hydrolysis and HDES-assisted processing.

## Contribution

The study introduces an integrated green processing strategy for converting agricultural residues into high-value nanocellulose.

## Key findings

- Subcritical alkaline pretreatment achieved 57.72% hemicellulose and 82.69% lignin solubilisation.
- Nanocellulose particles with 66% below 100 nm were produced using HDES and ultrasound.
- The nanocellulose showed good colloidal stability with a zeta potential of −33.0 mV.

## Abstract

This study investigates a sustainable and efficient approach to valorising barley straw by producing nanocellulose via an integrated subcritical alkaline hydrolysis and HDES-assisted processing pathway. Subcritical alkaline pretreatment under best processing conditions (150 bar, 200 °C, 125 min) enabled effective biomass fractionation, achieving average hemicellulose and lignin solubilisation of 57.72% and 82.69%, respectively. Subsequent purification of the pretreated solid fraction yielded cellulose fibres with an average cellulose yield of 41.97% and a purity of 87.87%. Nanocellulose was then obtained using a sequential HDES treatment followed by high-intensity ultrasound (HIUS), producing a sample (NC-BTW-3) in which 66% of particles exhibited diameters below 100 nm, 15.2% were between 100 and 200 nm, and 19% were within the 200–1000 nm range. The resulting nanocellulose demonstrated good colloidal stability, with an average zeta potential of −33.0 mV. Overall, the work highlights a green and effective processing strategy for the valorisation of agricultural residues into high-value nanocellulose suitable for bio-based material applications.