PREPARATION, CHARACTERIZATION AND APPLICATIONS AS HEAVY-METALS SORBENTS OF COVALENTLY GRAFTED THIOL FUNCTIONALITIES ON THE INTERLAMELLAR SURFACE OF MONTMORILLONITE

A novel type of heavy metal adsorbent was prepared by the covalent gra fting of a chelating sulfhydryl functionality [(3-mercaptopropyl)trime thoxysilane) in the interlamellar region of the smectite clay mineral montmorillonite. The new material (designated as thiomont) was charact erized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, X-ray fluorescence, and C-13 solid-state NMR spectroscopy. I ts approximate chemical formula was deduced to be .3Fe0.3Mg0.4O(16)(OH )(3)[OSi(OH)(2)(CH2)(3)SH](5). Thiomont was found to be an effective a dsorbent for Pb(II) and Hg(II) (70 and 65 mg of metal/g of adsorbent, respectively) but was less effective toward Cd(II) and Zn(II). Acid le aching was shown to be an effective method by which thiomont could be regenerated.