Adsorption studies of Cd(II) on ball clay: Comparison with other natural clays

Ball clay was found to exhibit excellent adsorption capacity toward Cd(II) ions over a wide concentration range. The adsorption capacity was studied by heating it at different temperatures. It was found that the sample heated at 200 °C showed maximum adsorption capacity toward Cd(II) ions. This research was focused on the effect of pH, time, temperature, adsorbent doses and initial Cd(II) concentration by batch experiments. The equilibrium data of Cd(II) adsorption were explained well by Langmuir and Freundlich adsorption isotherms. The kinetics data for the adsorption process obeyed pseudo-first-order and pseudo-second-order models at lower initial concentrations of Cd(II) while with the increased concentration of Cd(II) pseudo-first-order model failed. The Cd(II) desorption was performed using batch process with various desorbing solutions and 100% desorption was achieved with HCl solution.