Simulation of dye adsorption by beech sawdust as affected by pH

J Hazard Mater. 2007 Mar 22;141(3):668-79. doi: 10.1016/j.jhazmat.2006.07.033. Epub 2006 Jul 21.

Abstract

The effect of pH on the batch kinetics of methylene blue adsorption on beech sawdust was simulated, in order to evaluate sawdust potential use as low cost adsorbent for wastewater dye removal. The zero point of charge pH(pzc) of the sawdust, in order to explain the effect of pH in terms of pH(pzc), was measured by the mass titration and the automatic titration methods. The adsorption capacity, estimated according to Freundlich's model, indicate that increase of the pH enhances the adsorption behaviour of the examined material. The lower adsorption of methylene blue at acidic pH is due to the presence of excess H(+) ions that compete with the dye cation for adsorption sites. As the pH of the system increases, the number of positively charged sites decreases while the number of the negatively charged sites increases. The negatively charged sites favour the adsorption of dye cation due to electrostatic attraction. The increase in initial pH from 8.0 to 11.5 increases the amount of dye adsorbed.

MeSH terms

  • Adsorption
  • Coloring Agents / chemistry
  • Coloring Agents / isolation & purification*
  • Computer Simulation
  • Dust*
  • Fagus*
  • Hydrogen-Ion Concentration
  • Methylene Blue / chemistry
  • Methylene Blue / isolation & purification*
  • Models, Chemical
  • Waste Disposal, Fluid / methods
  • Water Pollutants, Chemical / chemistry
  • Water Pollutants, Chemical / isolation & purification*
  • Water Purification / methods
  • Wood

Substances

  • Coloring Agents
  • Dust
  • Water Pollutants, Chemical
  • Methylene Blue