Isolation and characteristics of nanocellulose from hardwood pulp via phytic acid pretreatment

Even though nanocellulose has been significantly sought after as a promising nanomaterial with great merits of biorenewability and excellent mechanical and optical properties, its preparation involves multiple steps with the utilization of strong acids or expensive enzymes, which has much hindered its commercialization. In this work, we addressed this challenge by developing a facile, green, and efficient combinatorial treatment for nanocellulose production by using phytic acid (PA) and sonication. The resultant nanocellulose had a maximum yield up to 92% when the treatment was conducted at 90 °C for 1 h, and the scanning probe microscope deciphered that the nanocellulose had a width of 22.0 ± 12.3 nm, a diameter of 5.5 ± 2.9 nm in height, and length ranged from 200 nm to 1 µm. These geometrical properties can be further improved by increasing PA pretreatment intensity. We further systematically characterized its dispersion property by using conductometric titration, Turbiscan, and Zeta potential, which indicated increased dispersion stability with the increasing pretreatment intensity. In addition, the isolated nanocellulose also shows good thermal stability over 300 °C. Overall, this acid pretreatment-assisted mechanical treatment approach greatly simplified the preparation of nanocellulose with a high yield under mild conditions.