Adsorption of chromium(VI) from aqueous solution by activated carbon derived from olive bagasse and applicability of different adsorption models

Mahogany sawdust was used to develop an effective carbon adsorbent. This adsorbent was employed for the removal of direct dyes from spent textile dyeing wastewater. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation. The equilibrium adsorption capacity of the sawdust carbon was determined with the Langmuir equation as well as the pseudo-second-order rate equation and found to be >300 mg dye per gram of the adsorbent. The most ideal pH for adsorption of direct dyes onto sawdust carbon was found to be 3 and below. The results indicate that the Mahogany sawdust carbon could be employed as a low cost alternative to commercial activated carbon in the removal of dyes from wastewater.

In this study, activated carbon (WA11Zn5) was prepared from waste apricot, which is waste in apricot plants in Malatya, by chemical activation with ZnCl(2). BET surface area of activated carbon is determined as 1060 m(2)/g. Activated carbon includes both micro and mesopores. Percentages of micropores and mesopores area are determined 36% and 74%, percentage of micropores and mesopores volume is 19% and 81%, respectively. The ability of WA11Zn5, to remove three dyes, methylene blue (MB), malachite green (MG), and crystal violet (CV), from effluent solutions by adsorption has been studied. The adsorption capacities of WA11Zn5 decreases in the order malachite green (MG)>methylene blue (MB)>crystal violet (CV). Equilibrium isotherms for the adsorption of three dyes on activated carbon were measured experimentally. Results were analyzed by the Langmiur, Freundlich, Dubinin-Redushkevich (D-R), Temkin, Frumkin, Harkins-Jura, Halsey and Henderson equation using linearized correlation coefficient at different temperature. The characteristic parameters for each isotherm have been determined. Models and the isotherm constant were evaluated depending on temperature. Langmiur and Frumkin equation is found to best represent the equilibrium data for three dye-WA11Zn5 systems.