Kinetics and Isotherm Studies of Methylene Blue Adsorption on Activated Carbon Derived from Chrysanthemum: Solid Waste of Beverage Industry

Chrysanthemum, a solid waste from beverage industry, was used as a raw material for the preparation of activated carbon through chemical activation with zinc chloride (ZnCl2), phosphoric acid (H3PO4) and ferric chloride (FeCl3). Briefly, the raw material was soaked in solutions of each chemical agent with ratio of 1:2 by weight for different times (1, 6, 12, and 24 h) and then carbonized at 500 degrees C for 1 h. The obtained activated carbons were characterized for their surface area and porosity by nitrogen gas adsorption at -196 degrees C. The highest surface area of 728 m(2)/g and total pore volume of 0.48 cm(3)/g were obtained from chrysanthemum activated with ZnCl2 for a soaking time of 24 h. The activated carbon with the highest surface area was then characterized for other physicochemical properties and used for the adsorption of methylene blue (MB). The effects of contact time and initial MB concentration were investigated in batch mode. The equilibrium adsorption time was 60 min and the adsorption data followed the pseudo-second order kinetics. The adsorption isotherm was best described by the Langmuir model. The maximum monolayer adsorption capacity of activated carbon prepared from chrysanthemum for MB was 491.0 mg/g, which is higher than activated carbons prepared from other biomasses using chemical activation. Therefore, chrysanthemum-based activated carbon could be used as alternative adsorbent for MB adsorption from waste effluents.