Preparation and characterization of the poplar micro-nano cellulose sustainable carbon spheres

In this study, cellulose extracted from the factory waste poplar was converted into value-added carbon spheres by means of hydrothermal carbonization (HTC). Oxygen-rich functional group carbon spheres with smooth morphology, good dispersibility, controllable particle size, high carbon content, and high calorific value were prepared under various process conditions. The optimum process conditions for obtaining good shape were temperature 250 ℃, time of 12 h, and cellulose dosage of 1 g. Under these conditions, the produced carbon microspheres exhibited smooth surface, high dispersion, and uniform particles. The Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), and elemental analyses indicated that the carbon content was as high as ~ 75% with increasing temperature and time, and the theoretically calculated higher heating values (HHV) were 29.4 MJ/kg. In addition, the H/C and O/C ratios were quite different relative to the raw materials. This demonstrates that the cellulose underwent dehydration, decarboxylation, and demethylation during hydrothermal carbonization to form carbon microspheres with oxygen-rich functional groups. Next, the carbon materials were analyzed by the porous structure of the sample (BET), thermogravimetric analyzer (TG), Raman, and X-ray diffraction (XRD), which further proved that the carbon microspheres were high-concentration aromatized amorphous non-porous carbon materials.