Preparation and mechanism analysis of morphology-controlled cellulose nanocrystals by H2SO4 hydrolysis of Eucalyptus pulp

Abstract

Cellulose from Eucalyptus pulp has been used as raw material for producing cellulose nanocrystals (CNCs). In this research work, H₂SO₄ hydrolysis was utilized in the production of CNCs. The effects of hydrolysis parameters, namely, H₂SO₄ concentration (30, 40, and 50 wt%), hydrolysis time (30, 60, and 90 min), and hydrolysis temperature (60, 70, and 80 °C), on the CNC structure were examined. The physical and chemical properties of Eucalyptus pulp and CNCs were characterized using different techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), and thermal gravimetric analysis (TGA). The results showed the optimal condition was at 50 wt% of H₂SO₄ concentration, 60 min hydrolysis time, and 60 °C hydrolysis temperature, which yielded 75.51% ± 1.51 % of crystallinity and 4.03 ± 0.10 nm of crystal size. Furthermore, it was also determined that an increase in H₂SO₄ concentration, time, or temperature led to a lower percentage of crystallinity and reduction in crystal size. CNCs were noted to be more thermally stable than the Eucalyptus pulp. Thus, this method could be an alternative way to create a new product in the paper industry.