Physicochemical properties of “green” nanocrystalline cellulose isolated from recycled newspaper

Abstract

“Green” nanocrystalline cellulose (NCC) was isolated through an acid hydrolysis process from recycled newspapers and prepared via treatment with NaOH and NaClO₂. Morphological characterization and physicochemical property measurements were executed using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). FTIR and chemical composition analysis demonstrated that lignin and hemicellulose structures were removed using different pretreatment steps with NaOH and NaClO₂. From the SEM results, it was discovered that the size of purified cellulose fibrils reduced to a great extent, and the structure of cellulose microfibers became smoother and cleaner due to the removal of lignin with other extracts. The XRD analysis results revealed that NCC exhibits the highest crystallinity index after acid hydrolysis of bleached cellulose microfibers. TEM and AFM analysis revealed that the rod-like structure of NCC was obtained with size 5.78 ± 2.14 nm wide and 121.42 ± 32.51 nm long. The TGA results suggested that the thermal stability of the NCC was affected mainly by the dehydration reaction caused by sulphate groups. The isolated nanocrystalline cellulose attracts great interest as an inexpensive bio-based filler in polymer nanocomposites.