Preparation and performance comparison of cellulose-based activated carbon fibres

Activated carbon fiber (ACF) is widely used sorbent material for wastewater treatment. Three natural cellulosic fibres (kapok, cotton, and ramie) and three regenerated cellulosic fibres (bamboo fiber, viscose, and lyocell) are used to prepare ACFs using chemical activation. These ACFs are characterized using scanning electron microscope, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) testing, elemental analysis, adsorption property and nitrogen adsorption-desorption. XRD and FTIR spectrum of all six cellulosic ACFs are almost similar showing that ACFs have almost same chemical and physical composition. All cellulosic ACFs are constituted of C, H, ash and O, but C content is higher in natural cellulosic fibres. Surface morphology and surface area of cellulosic ACFs play the basic role in adsorption. The 2nd order pseudo kinetic model is fitted for all cellulosic ACFs as R-2 > 0.99 and adsorption controlling process is chemical sorption. The adsorption capacity of the kapok-based ACFs is best, owing to their hollow structure, the micropores on surface and high specific surface area. Bamboo, ramie and cotton based ACFs also have high adsorption but they need more time to adsorb impurities than kapok based ACFs. Viscose based ACFs shows moderate adsorption, while the least adsorption is shown by the lyocell based ACFs because of their smooth and uniform structure. Adsorption analysis and other properties evaluation show that kapok fiber is the best precursor than other five cellulosic fibres.