Preparation of a novel activated carbon from jujube stones (Ziziphus jujuba) for the removal of basic and acid dyes

摘要

The present work studies the effect of carbonization temperature, impregnation ratio and activation temperature on the preparation of activated carbon from jujube stones (JB-AC) using potassium hydroxide as an activating agent. Conditions to develop porosity of activated carbon to ameliorate adsorption of Rhodamine B and Orange 11 dyes were investigated. The effect of various experimental parameters on adsorption such as time, adsorbent dose, pH and temperature was studied to evaluate adsorption capacities of JB-AC. Equilibrium data were analyzed using the well-known Langmuir and Freundlich models. The results indicated that the Langmuir isotherm model was found to best fit adsorption data of both dyes onto the prepared material. Maximum adsorption capacities of Rhodamine B and Orange II onto JB-AC were 207.5 and 498.5 mg/g, respectively. Corresponding results for the commercial Merck activated carbon and jujube stones raw material were 133 and 68.4 mg/g for Rhodamine B and 297.7 and 53.5 mg/g for Orange II. Adsorption kinetics of both dyes followed the pseudo-first-order and pseudo-second-order rate models. Thermodynamic parameters study showed that Rhodamine B and Orange II sorption process on all adsorbents was spontaneous and endothermic. These results show that jujube stones could be valorized into a cost-effective activated carbon that can compete very favorably for the removal of dyes such as Rhodamine B and Orange II from their aqueous solutions.