Isolation of dicarboxy cellulose nanocrystal from spent fungi substrate and redispersion with gelatin

Dicarboxylic cellulose nanocrystals (DCNCs) from spent fungi substrate were freeze-dried with gelatin to obtain nanoscale-powder that was easy to redisperse and store. The agglomeration of nanocellulose during the drying process led to its performance degradation, which was the major limit to its productization and economy. In this study, The DCNCs were obtained via the sequential periodate-chlorite process without any mechanical component, and its structural and morphological properties were characterized by the transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The XRD results showed the cellulose I structure was maintained, however, the crystallinity index decreased because of the oxidation. The TEM analysis revealed that DCNC behaved rod-shaped with the average length and width of 281.47 nm and 20.8 nm, respectively. The gelatin and nanocellulose were homogenized through different conditions, then washing with hot water after the freeze-drying. Under the conditions of gelatin 2%, pH 7, and homogeneous (16000 r/min, 20 min), the redispersed DCNC suspension with the best light transmittance and stability was obtained. The introduction of gelatin not only minimized aggregation during the dehydration but also ensured excellent redispersion kinetics and stability. This study would provide an efficient and convenient route for the redispersion and storage of nanocellulose, aiming to realize its industrial application.