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 Pb 2+ > Cu 2+ > Zn 2+. A high concentration of co-existing ions such as Ca 2+ and Mg 2+ depressed the adsorption of heavy metal. Adsorption data showed that metal adsorption 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.

Hierarchically assembled mesoporous ZnO nanorods for the removal of lead and cadmium by using differential pulse anodic stripping voltammetric method

“…The selectivity of ZnOs is, therefore, in the order of Pb>Cd which could be attributed to the higher electronegativity of lead (2.33) than cadmium (1.69), which has a stronger affinity for the metal oxides [31,32].…”

Preparation of new polysulfone capsules containing Cyanex 272 and their properties for Co(II) removal from aqueous solution

“…The sorption behavior of an adsorbent for a metal ion depends on a combined action of solution pH, electronegativity and ionic radius of metal ion [53,56,57]. Electronegativity of a metal ion indicates the tendency of the metal ion attraction to the negatively charged sites.…”

Potential of Sawdust as a Green and Economical Sorbent for Simultaneous Preconcentration of Trace Amounts of Cadmium, Cobalt, and Lead from Water, Biological, Food, and Herbal Samples

“…Recovery of lead, cadmium, and cobalt ions increased rapidly with increasing pH, and the maximum recovery for metals was achieved at pH 5.0 to 7.0. To understand the effect of pH on the sorption, we should explain the adsorption mechanism (Marin and others ; Shukla and others ; Porte and others ; Yasemin and others ; Asadi and others ; Arief and others ; Lim and others ). Sawdust mainly consists of cellulose (45% to 50%), lignin (23% to 30% for softwood and 18% to 25% for hardwood), and tannins that have many hydroxyl groups.…”