Carbon spheres obtained via citric acid catalysed hydrothermal carbonisation of cellulose

Abstract

Well dispersed micrometre sized carbon spheres were prepared by citric acid catalysed hydrothermal carbonisation (200–240°C) of cellulose. The obtained product was characterised using scanning electron microscopy, field emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared and X-ray photoelectron spectroscopy. The results showed that the shape and size of the obtained carbons were highly dependent on the concentration of catalyst, hydrothermal temperature and reaction time. The optimal citric acid concentration, temperature and reaction time for the synthesis of carbon with smooth and regular sphere morphology were 2·5 wt-%, 240°C and 12 h respectively. The formation of the carbon spheres from cellulose followed the paths of hydrolysis, dehydration, polymerisation and aromatisation. The obtained carbon spheres consisted of aliphatic and aromatic structures and rich in oxygen containing functional groups on the surface.

Keywords:

• Cellulose
• Citric acid
• Hydrothermal carbonisation
• Carbon spheres

This project was financially supported by the Research Fund for the Doctoral Program of Higher Education of China (20100062110003), the National Natural Science Foundation of China (no. 31170545) and the Fundamental Research Funds for the Central Universities (DL11EB01).