Equilibrium and Kinetics of Adsorption of Ni (II) and Pb (II) Ions on Cow Bone ASH

The adsorption capacity of cow bone ash for Ni (II) and Pb (II) ions in aqueous solution was studied as functions of initial metal ion concentration and time in a batch system. Results showed that adsorption increased with Ni (II) and Pb (II) concentration. Adsorption isotherms such as Langmuir, Freundlich, Dubinin-Radushkevich, Harkins-Jura and Henrys isotherms were applied to the adsorption data. Isotherm parameters showed that the data for Ni (II) sorption was better correlated than Pb (II) data. Ni (II) sorption correlated at 0.986, 0.945, 0.903, 0.884 and 0.768 for Langmuir, Freundlich, Harkins-Jura Dubinin-Radushkevich and Temkin isotherms respectively. The maximum adsorption capacity was found to be 0.079mg/g and 0.236 mg/g for Pb (II) and Ni (II) respectively. The kinetic behaviour of Ni (II) and Pb (II) ions towards the adsorbent was studied with two rate models pseudo first-order and pseudo second- order equation. The pseudo- first order rate model fitted the Pb (II) sorption (R2 = 0.941) while the pseudo second order rate model correlated the Ni (II) data ( R2= 0.999). Maximum percent removal efficiency was 99.5 % at 50 minutes for Pb (II) while that of Ni (II) was 32.83 % at 60 minutes.