Chicken eggshells remove Pb(II) ions from synthetic wastewater

Abstract

Disposal of eggshell wastes has become one of the most serious problems for poultry industries. Efficient utilization of eggshell wastes for other application may solve this problem. This study uses eggshell as an additive to precipitate divalent lead cations [Pb(II)] from aqueous solutions in the pH range of 2-5. Owing to high CaCO3 content, eggshell precipitates Pb(II) to form lead carbonates, which will then settle on the surface of eggshell. Scanning electron microscopy and energy dispersive X-ray analysis of the eggshell exposed to Pb(II) solutions indicated the deposition of lead carbonates on the surface of the eggshell. On reducing the particle size of an eggshell from 750 to 100 μm, the Pb(II) removal efficiency of it increased from 30.7 to 99.6% at an initial Pb(II) concentration of 1045 mg/L. It was found through isotherm experiments that eggshell powder (100 μm) was capable of sorbing 577 mg Pb/g compared with 154 mg Pb/g by eggshell particles (750 μm). The biosorption isotherms were well represented by either Langmuir or Toth models. For eggshell powder, the rate of kinetics was fast with 35 min sufficient to achieve Pb(II) biosorption equilibrium. © Copyright 2013, Mary Ann Liebert, Inc. 2013.