Complexant-montmorillonite nanocomposites for heavy metal binding in sulfide tailing

Complexant-montmorillonite nanocomposites were successfully prepared through the intercalation of the complexants cysteamine hydrochloride (CSH), 1,6-diaminlhexane (DA), tetraethylenepentamine (TEPA) with different functional group and molecular weight in this work. More importantly, it was proved that the heavy metal stabilization property of montmorillonite improved significantly after intercalation of complexants through characterization by XRD and SEM-EDS. Here, the complexant-montmorillonite nanocomposites exhibited strong pH buffering effects. The Zn stabilization rate was prone to 100% by adding DA or TEPA modified montmorillonite (DA-Mt or TEPA-Mt) into the tailings, and the releasing rate of As and Mn from tailings also decreased greatly. Generally, the Zn, Pb, Mn and As stabilization effects of both TEPA-Mt and DA-Mt were much better than that of CSH modified montmorillonite, which suggested that the heavy metal complexing abilities of complexant-montmorillonite nanocomposites highly depended on the functional group and molecular weight of the complexants. In this study, electrostatic adsorption, physical adsorption, ion exchange and complexation worked together and produced good heavy metal stabilization effect. Our findings could provide an important reference for the synthesis of efficient stabilization nanomaterials.