The use of an agricultural waste material, Jujuba seeds for the removal of anionic dye (Congo red) from aqueous medium

The feasibility of using Indian Jujuba Seeds (IJS) (Zizyphus maruritiana), abundantly available in and around the Nallamalla forest in Andhra Pradesh, for the anionic dye (Congo red, CR) adsorption from aqueous solution, has been investigated as low cost and eco-friendly adsorbent. Adsorption studies were conducted on a batch process, to study the effects of contact time, initial concentration of CR, pH and temperature. Maximum colour removal was observed at pH 2. The equilibrium data was analyzed by the Langmuir, the Freundlich and the General isotherms. The data fitted well with the Langmuir model, with a maximum adsorption capacity of 55.56 mg g(-1). The pseudo-second-order kinetics was the best for the adsorption of CR, by IJS (Z. maruritiana) with good correlation. Thermodynamic parameters, such as standard free energy change (Delta G degrees), standard enthalpy change (Delta H degrees) and standard entropy change (Delta S degrees), were analyzed. The results suggest that IJS (Z. maruritiana) is a potential low-cost adsorbent for the CR dye removal from synthetic dye wastewater. (C) 2011 Elsevier B.V. All rights reserved.