Using wood and bone ash to remove metal ions from solutions

Abstract

In the present work, wood and bone ash were used to remove metal cations from solutions. Cation-removal capacity of the ashes was analyzed by potentiometric titration. It was found that the capacity of wood ash was two times higher (37.3 meq g-1) than bone ash (15.2 meq g-1). Kinetics of metal ions removal by both ashes was described with pseudo-second order equation and Langmuir model was employed to describe equilibrium of the process. Wood ash had better removal properties than bone ash - at the same experimental conditions biosorption capacity at equilibrium for wood ash was 2 times higher (244 mg g-1) than for bone ash (123 mg g-1). Promising results were also obtained for wood ash, which was capable of removing 67.9 % of Zn(II) ions, 70.4 % of Cd(II) ions, 92.8 % of Cu(II) ions and 99.1 % of Cr(III) ions from model solution of wastewater from metallurgical industry and 84.5 % of Cr(III) ions from the postbiosorption solution from the production process of biological feed additives. The utilization of ashes of biological origin was found to be a promising alternative to conventional processes of wastewater treatment. © 2009 Global NEST.