In this paper, we investigate on the preparation of waste cotton fabric-based activated carbons by different methods. Two different kinds of carbon materials are prepared from waste cotton fabric, the structure and properties were characterized using instrumental analyses such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). It is revealed that the products prepared using one-step process are composed of macroporous carbon network , which looks like sponge-type morphology, and exhibit the high values of qiodine (1,198 mg/g) and qmb (235.6 ml/g), showing their potential usage as adsorbent.
To study the hydrothermal behavior of cotton fiber, the carbonization process and structural evolution of discarded or waste cotton fiber (WCF) under hydrothermal conditions were investigated using microcrystalline cellulose (MCC), and glucose was used as a model compound. Results showed that high temperature was beneficial for the hydrolysis of discarded cotton fiber, and the yield of sugar was 4.5%, which was lower than that of MCC (6.51%). WCF and MCC were carbonized at 240–~260°C and 220–~240°C, respectively, whereas the carbonization temperature of glucose was lower than 220°C. The C/O ratios of WCF and glucose hydrothermal products were 5.79 and 5.85, respectively. The three kinds of hydrothermal carbonization products had similar crystal structures and oxygen-containing functional groups. The carbonized products of WCF contained many irregular particles, while the main products of glucose carbonization were 0.5-mm-sized carbon microspheres (CMSs). Results showed that glucose was an important intermediate in WCF carbonization and that there were two main pathways of hydrothermal carbonization of cotton fibers: some cotton fibers were completely hydrolyzed into glucose accompanied by nucleation and then the growth of CMSs. For the other part, the glucose ring of the oligosaccharide, formed by the incomplete hydrolysis of cotton fibers under hydrothermal conditions of high temperature and pressure, breaks and then forms particulate matter.