Multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) onto natural bentonite clay.

The present work was aimed at evaluating the multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) ions onto natural bentonite. The bentonite clay adsorbent was characterized for physical and chemical properties using X-ray diffraction, X-ray fluorescence, Brunauer-Emmett-Teller surface area and cation exchange capacity. The column performance was evaluated using adsorbent bed height of 5.0 cm, with varying influent concentrations (10 mg/L and 50 mg/L) and flow rates (1.4 mL/min and 2.4 mL/min). The result shows that the breakthrough time for all metal ions ranged from 50 to 480 minutes. The maximum adsorption capacity was obtained at initial concentration of 10 mg/L and flow rate of 1.4 mL/min, with 2.22 mg/g of lead(II), 1.71 mg/g of cadmium(II) and 0.37 mg/g of manganese(II). The order of metal ions removal by natural bentonite is lead(II) > cadmium(II) > manganese(II). The sorption performance and the dynamic behaviour of the column were predicted using Adams-Bohart, Thomas, and Yoon-Nelson models. The linear regression analysis demonstrated that the Thomas and Yoon-Nelson models fitted well with the column adsorption data for all metal ions. The natural bentonite was effective for the treatment of wastewater laden with multi-metals, and the process parameters obtained from this work can be used at the industrial scale.