Preparation and characterization of novel organo-clay minerals for Hg(II) ions adsorption from aqueous solution

Novel organo-clay minerals for adsorption of Hg(II) ions were prepared. The clay minerals were grafted with 2-(3-(2-aminoethylthio)propylthio)ethanamine (AEPE). AEPE-montmorillonite and AEPE-hectorite were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA), CHN element analysis (EA) and surface area analysis. The XRD patterns indicated that the chelating agents (AEPE) were mainly grafted on the external surface of montmorillonite while AEPE was grafted on both the external and interlayer surfaces of hectorite. The results from IR, TGA and EA showed a difference in chemical composition of the unmodified and modified clay minerals. The results confirmed that montmorillonite and hectorite were modified with the desired organic groups. The extent of ligand loading depended on the nature of the clay mineral. The AEPE-modified clay minerals were good chelating materials for Hg(II) ions, compared to the unmodified clay minerals. The adsorption capacity for Hg(II) of AEPE-montmorillonite and AEPE-hectorite was 46.1 and 54.7 mg g− 1, respectively, for solution containing 140 mg L− 1 Hg(II) ions (pH 4).