Influence of Pretreatment with Soda (NaOH) on the Structural Characteristics of Activated Carbon Prepared by Chemical Means with H 3 PO 4 from Rice Bran

Abstract

The purpose of this work is the preparation of best activated carbons from rice bran through carbonization at 500°C preceded by an impregnation in a 25% H3PO4 solution. We carry out the study of the effects of pretreatment with soda and Xp impregnation ratio on characteristics of three series of activated carbons SR0N, SR1N and SR2N corresponding to the pre-treatment with soda 0 M, 1 M and 2 M respectively. The iodine value and the textural properties of prepared carbons have been determined. The maximum iodine value, 893 mg.g-1 is obtained in the SR2N series for Xp = 2.5. In the SR1N series the maximum iodine value 866 mg.g-1 is obtained for Xp = 4. Also activated carbons CS1 (SR1N - Xp = 4) and CS2 (SR2N - Xp = 2.5) have the following characteristics: specific surface area equal to 1711.6 and 1558.5 m2g-1 and porous volumes of 1.234 and 1.385 cm3/g respectively. Studies conducted on phenol adsorption and thermodynamic showed that CS1 is slightly more effective than CS2 with a spontaneous and exothermic reaction. On the other hand, their adsorption isotherms are best described by the Langmuir model than that of Freundlich