MICROWAVE-TREATED BENTONITE FOR REMOVAL OF LEAD FROM WASTEWATER

Abstract

Clay-based materials are promising adsorbents for removal of various pollutants from wastewater. This work is aimed to study the changes in structure and adsorption capacity of microwave-treated bentonite after adsorption of lead(II) ions. The structural investigation of the microwave-treated sample reveals that a partial destruction of silica skeleton takes place, and new surface nucleation centers are formed during microwave processing. The adsorption of Pb2+ on natural bentonite occurs on heterogeneous adsorption sites, whereas the removal of lead on microwave-treated sample is accompanied by the formation of plumbophyllite microcrystals. The natural and microwave-treated adsorbents were tested for lead adsorption in batch experiments. The results were fitted according to Langmuir, Freundlich, Toth, Redlich-Peterson, and Langmuir-Freundlich isotherms of adsorption. The microwave-treated samples revealed substantially higher efficiency towards the removal of lead, their maximal adsorption capacity was 114.7 mg g–1, whereas natural samples showed only 31 mg g–1. .