Sorption of Cd(II) and Pb(II) from aqueous solutions by a low-rank coal (leonardite)

An extensive study of the competitive adsorption between both metals was performed under the same conditions of the individual experiments. The extended Langmuir model was used to fit the experimental data to a series of 3D response surfaces. For binary systems, the maximum adsorption capacities of Cd(II) and Pb(II) were calculated as 0.27 mmol g−1 (30.6 mg g−1) and 0.57 mmol g−1 (118.7 mg g−1), respectively. Cd(II) adsorption was found to be more sensitive than Pb(II) to the presence of a competitive sorbate.