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Optimization of homogenization-sonication technique for the production of cellulose nanocrystals from cotton linter

Hemmati, Farshad, Jafari, Seid Mahdi, Taheri, Ramezan Ali
International journal of biological macromolecules 2019 v.137 pp. 374-381
Fourier transform infrared spectroscopy, X-ray diffraction, acid hydrolysis, atomic force microscopy, cellulose, cotton, crystal structure, drugs, homogenization, nanocrystals, particle size, solvents, sulfuric acid, thermal stability, thermogravimetry, transmission electron microscopy, ultrasonic treatment, water holding capacity
Recently, cellulose nanocrystals (CNCs) have attracted a significant interest in different fields including drug delivery, biomedical, and food applications. In this study, homogenization-ultrasonication as a non-hazardous, time-saving, and organic solvent free technique was applied for fabrication of CNCs from cotton linter, containing over 90% cellulose. First, acid hydrolysis was applied on raw cellulose using sulfuric acid at 55, 60 and 65% for 3, 5 and 7 min and at various homogenization speeds. Final CNCs were produced by ultrasonication (350 W) for 3 min. The physicochemical properties of CNCs, particle size, X-ray diffraction (XRD) pattern, Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), atomic force microscopy (AFM) and transmission electron microscopy (TEM) were studied. Production yield of CNCs was 59–72%, and their water holding capacity was two times higher than raw cellulose. The average length of CNCs was 133 nm with a width of 10 nm and the XRD pattern revealed a 82% crystallinity degree. The FTIR spectrum detected almost similar frequencies in the raw and crystalline cellulose, while intensity of CNC peaks was reduced. TEM results showed rod-like CNCs with a length of 229 nm. TGA results also showed that thermal stability of CNCs was reduced compared to raw cellulose.