Removal of Heavy Metals by Sawdust Adsorption: Equilibrium and Kinetic Studies

Abstract

Adsorption of heavy metals by sawdust was investigated to evaluate the effectiveness of using sawdust to remove heavy metals from aqueous solutions. Kinetic and isotherm studies were carried out by considering the effects of initial concentration and pH. The adsorption isotherms of heavy metals fitted the Langmuir or Freundlich model reasonably well. The adsorption capacity of metal was in the order Pb2+ > Cu2+ > Zn2+. A high concentration of co-existing ions such as Ca2+ and Mg2+ depressed the adsorption of heavy metal. Adsorption data showed that metal adsorp- tion on sawdust follows a pseudo-second-order reaction. Kinetic studies also indicated that both surface adsorption and intraparticle diffusion were involved in metal adsorption on sawdust. Column studies prove that sawdust could be effective biosorbent for the removal of heavy metals from aqueous phase.