Synthesis and characterization of activated carbon fibers derived from corn silk and its application in p-Cresol removal

This study reports the synthesis of activated carbon fibers (ACF) from corn silk via physical and chemical activation using CO2 and KOH as activation agents, respectively. The influence of activation temperature, mode of activation, and an activation agent (KOH) to fiber (A/F) ratio on the texture, structure, and pore characteristics of ACF were investigated. ACF were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and nitrogen adsorption-desorption isotherm studies. The characterization results indicate that the corn silk was successfully converted into thermally stable microporous ACF while retaining their fibrous form. The optimum A/F ratio and activation temperature of chemically activated carbon fibers (CACF) were found to be 3 and 850 degrees C providing a highly porous structure and a specific surface area of 1,363 m(2)/g. The maximum surface area in case of physically activated carbon fibers (PACF) at optimum conditions was determined to be 934 m(2)/g. The synthesized ACF adsorption experimentation was carried out with p-Cresol adsorption. The adsorption of p-Cresol on ACF followed Langmuir isotherm and the maximum adsorption capacity of CACF and PACF was determined to be 476 and 400 mg/g, respectively. The reaction kinetics of p-Cresol on ACF was found to follow pseudo-second-order kinetics model with reaction rates of 0.0055 g/mg min and 0.015 g/mg min for CACF and PACF, respectively. The removal efficiency of p-Cresol using CACF and PACF exceeded 97% and 75%, respectively, at optimum conditions. These results imply that corn fiber-based ACF can be used effectively as an adsorbent for the removal of p-Cresol from wastewater steams.