MESOPOROUS ACTIVATED CARBON FIBERS FROM LIGNOCELULLOSIC MATERIALS: ADSORPTION STUDIES

摘要

High surface area and highly mesoporous activated carbon fibers (ACF) were obtained by physical activation of natural precursors (vetiver roots and bagasse) with steam and chemical activation using phosphoric acid. The textural characteristics of the activated were determined by nitrogen adsorption study and mercury porosimetry and showed that interesting porosity were obtained (S_(BET) up to 1600 m~2/g) and high mesoporous volume (V_(mes) up to 1.6 cm~3/g). A study comparing the Brunauer-Emmet-Teller (BET) and the Freundlich equation when applied to N_2 adsorption isotherm at 77 K was done. The ability of the developed activated carbons fibers to remove methylene blue and phenol from aqueous solution was investigated. Isotherm and kinetic studies were carried out to determine various factors necessary to establish adsorption treatment process. Evaluation of different isotherm and kinetic models was done to study their accuracy for modelling our adsorption data, allowing us to bring some informations on the adsorption mechanism. We also demonstrate that a recently developped fractal kinetic model could be applied to the adsorption kinetic data giving low normalized standard deviation values.