Enzymatic-mediated production of cellulose nanocrystals from recycled pulp

Endoglucanase was used to hydrolyze recycled pulp to produce cellulose nanocrystals. The highest yields of cellulose nanocrystals were obtained by treatment with 84 EGU of endoglucanase per 200 mg recycled pulp at 50 °C for 60 min of microwave and conventional heating. Of the two modes of heating investigated, microwave heating at each treatment gave a higher yield than conventional heating. Transmission and scanning electron microscopic analysis of suspensions showed cellulose nanocrystals with widths of 30 nm to 80 nm and lengths of 100 nm to 1.8 μm). This was within range of the length of cellulose crystals (100 nm to 3.5 μm) obtained using dynamic light scattering analysis. The average zeta potential of cellulose nanocrystals was −31.37 mV. X-ray diffraction of cellulose nanocrystals, recycled pulp and residues of recycled pulp shows a gradual change in the particle size.