Adsorption Equilibrium, kinetics and thermodynamics of methylene blue from aqueous solutions using biopolymer oak sawdust composite

Oak sawdust (OSD), furniture industrial waste was chemically treated with 0.1N NaOH to give hydrolyzed oak sawdust (HOSD) which was immobilized on alginate biopolymer. Hydrolyzed oak sawdust composite (HOSDC) was utilized as low-cost adsorbent to remove basic dye (methylene blue, MB) from aqueous solution. HOSD and HOSDC were characterized by using Scanning electron microscope (SEM), thermo gravimetric analysis (TGA) and infrared spectrometer analysis (FTIR). The adsorption of (MB), whose isotherms are modeled according to Langmuir, Freundlich and Temkin, were studied at a variety of physical and chemical conditions. The data fitted very well with Freundlich isotherm. Batch adsorption models, based on the assumption of pseudo-firstorder, pseudo-second-order and intraparticle diffusion mechanism, showed that kinetic data follow closely pseudosecond-order and intraparticle diffusion. In addition, various thermodynamic parameters, such as standard Gibbs free energy (∆G◦), standard enthalpy (∆H◦), standard entropy (∆S◦), and the activation energy (Ea) were calculated. The adsorption process of MB dye onto HOSDC was found to be spontaneous and endothermic process. Furthermore, a single-stage batch adsorber was designed for the removal of methylene blue by HOSDC based on the equilibrium data obtained. [Journal of American Science 2010;6(6):267-283]. (ISSN: 1545-1003).