Removal of Basic Dye Methylene Blue from Aqueous Solutions Using Sawdust and Sawdust Coated with Polypyrrole

This research deals with the application of wood sawdust obtained from walnut and its polypyrrole (PPy) coated form for the removal of methylene blue (MB) from aqueous solutions. MB, a typical cationic dye, was used as a test probe. Coating of sawdust was carried out chemically via direct addition of chemical oxidant (FeCl3) on the sawdust which was previously soaked in monomer solution (0.2 M pyrrole). Adsorption experiments were carried out using both batch and fixed bed column systems. The effects of different system variables such as adsorbent dose, initial dye concentration, pH of test solution, contact time and breakthrough curves were studied. In order to find out the possibility of reuse, desorption study was also carried out in this investigation. It was found that both SD and PPy/SD are efficient and cost-effective adsorbents for the removal of MB dye from aqueous solutions. The collected data in this research indicate that compared with PPy/SD, adsorption of MB by SD is not a very pH dependent process, at least from pH 4 to 10. Higher sorption percentage of MB is obtained for PPy/SD at alkaline pHs.