Dye adsorption by prehydrolysed beech sawdust in batch and fixed-bed systems.

The batch and column kinetics of methylene blue and red basic 22 adsorption on mild acid-hydrolysed beech sawdust were investigated, using untreated beech sawdust as control, in order to explore its potential use as a low cost adsorbent for wastewater dye removal. The adsorption capacities, estimated according to Freundlich's model, and the adsorption capacity coefficient values, determined using the Bohart and Adams' bed depth service model, indicated that prehydrolysis enhances the adsorption properties of the original material. This enhancement can possibly be attributed to (a) the removal of the hemicelluloses during sulphuric acid treatment, resulting in the 'opening' of the lignocellulosic matrix's structure and the increasing of the BET surface area and (b) the activation of the material's surface owing to an increase in the number of dye binding sites.