Preparation of CO 2 activated carbon from corncob for monoethylene glycol adsorption

Abstract

Activated carbon was produced from corncob using CO 2 for the activation process. This research investigated the effect of the remaining volatile matter in corncob char combined with CO 2 activation to improve the pore properties of corncob activated carbon. The pore structure was characterized using the Brunauer–Emmett–Teller (BET) surface area test, total pore volume, mesopore volume, micropore volume and average pore diameter. This study discovered that the amount of volatile matter in corncob char is about 17–25% and results in a BET surface area range of 919–986 m 2 g −1 by the CO 2 activation process. Therefore, the optimum temperature for the activation process should start at 450–550 °C and increase until the temperature reaches to 800 °C. Activated carbon from corncobs at 450–550 °C contained a suitable amount of volatile matter, 17–25%, for pore development. The Langmuir and Dubinin–Radushkevich (D–R) adsorption models were used to study the equilibrium isotherms, the isotherm constants and the adsorption capacity of monoethylene glycol by corncob activated carbon and commercial activated carbon. The values of Langmuir isotherms Q max of corncob activated carbon and commercial activated carbon were 4.509 and 5.910 mo l MEG k g adsorbent − 1 , respectively. The D–R isotherms were described the adsorption capacity and the free energy ( E) of adsorption. The values of E (kJ mol −1) confirmed that monoethylene glycol adsorption by corncob activated carbon and commercial activated carbon was a physisorption.