Studies of Pb(II) Adsorption onto Local Adsorbent

Abstract

The study was carried out to assess the suitability of a locally sourced clay as potential adsorbent for the removal of Pb(II) ions from aqueous solutions following batch mode of operation. The study investigated the effect of varying contact time, solution pH, adsorbent dose and initial concentration of metal ion on sorption. Batch equilibrium and kinetic experiments were conducted at 25°C, using <0.02 mm particle sizes of clay. The kinetic and equilibrium models were fitted employing the non-linear regression method, using a trial-and-error procedure in the Microsoft Excel solver. In order to determine the best fit isotherm, five error analysis functions were used: hybrid fractional error function, Marquardt’s percent standard deviation, average relative error, sum of the errors squared and sum of the absolute errors. However, the sum of normalized error was further employed in order to have a better comparison between the error functions sets for the isotherm models. With the highest R2 value of 0.9887 and lowest sum of normalized error value of 0.0108, the Sips isotherm fitted the equilibrium data better than the other isotherm models. The pseudo-second order model gave the best fit to the kinetic data as it had the lowest standard error of the estimates value of 3.22x10-6 and the highest coefficient of determination, R2 values of 0.9887 for the adsorption of Pb(II) onto Ikpoba clay.