Effect of particle size on the sorption of lead from water by different species of sawdust: Equilibrium and kinetic study

Abstract

Both the effect of particle size and initial concentration on the adsorption of lead by sawdust of two timber species were investigated using batch experimental equilibrium and kinetic studies. A 100% lead removal efficiency was recorded for the optimum particle size of 1.18 mm for Pycnanthus angolensis and 0.85 mm for Khaya ivorensis at an initial lead concentration of 10 mg/L. Freundlich isotherm (0.83 ≤ R2 ≤ 0.96 for Khaya ivorensis and 0.94 = R2 = 1.0 for Pycnanthus angolensis) performed better than Langmuir and Temkin isotherms. The Dubinin-Radushkevich isotherm was used to ascertain the sorption mechanism. Mean sorption energy (12.48 kJ/mol for Pycnanthus angolensis and 13.42 kJ/mol for Khaya ivorensis) indicated that adsorption was by ion exchange. The pseudo-first order kinetic model (0.96 = R2 = 1.0 for Khaya ivorensis and 0.90 ≤ R2 ≤ 1.0 Pycnanthus angolensis) performed better than others with respect to R2 values, while the intraparticle diffusion model performed better than the other kinetic models with respect to absolute mean error (AME).