Synergic effect of tungstophosphoric acid and sonication for rapid synthesis of crystalline nanocellulose

• Sonication accelerates the production of nanocellulose using tungstophosphoric acid.
• Only 10 min sonication at 225 W power needed for nanocellulose production.
• Nanocellulose having diameter 15–35 and >100 nm in length with 88% crystalline.

The utilization of sonication in combination with tungstophosphoric acid (PWA) catalyst reduces dramatically the time of operations from 30 h to 10 min by using an optimum sonication power of 225 W. The basic cellulosic structure is maintained, allowing preparing high-quality nanocellulose. The size of the nanocellulose obtained was in the range from 15 to 35 nm in diameter and several hundred nanometers in length, with a high crystallinity of about 88%. The nanocellulose shows a surface charge of −38.2 mV which allows to obtaina stable colloidal suspension. The surface tension of the stable, swollen aqueous nanocellulose was close to that of water. These characteristics, together with the fast procedure allowed from the synergic combination of PWA and sonication, evidence the high potential of the proposed method for the industrial production of nanocellulose having the properties required in many applications.