Highly effective adsorption of heavy metal tons by a thiol-functionalized magnesium phyllosilicate clay

A thiol-functionalized layered magnesium phyllosilicate material (called Mg-MTMS), prepared bir a direct and cost-effective cc-condensation synthesis, has been investigated as a high-capacity adsorbent for heavy metal ions. Structural characterization by powder X-ray diffraction, infrared spectroscopy, solid-state C-13 and Si-29 NMR spectroscopies, and elemental analyses confirms the smectite-type structure and the high organic moiety content of this material. Mg-MTMS was found to be highly effective far the adsorption of Hg(II), Pb(II), and Cd(III) ions, exhibiting unprecedented metal ion uptake capacities of 603,365, and 210 mg of metal/g of adsorbent, respectively Mg-MTMS shows an equivalent affinity for the three metal ions, removing them from mixed metal solutions with an equal ion uptake capacity (similar to 400 mg of metal/g of adsorbent). Metal-loaded Mg-MTMS can be regenerated by acid treatment without altering the adsorbent properties. The high effectiveness of Mg-MTMS far the capture of metal ions is attributed to hath the high concentration of complexing thiol groups (6.4 mmol of SH/g of Mg-MTMS) and the expansion capability of the framework, which facilitates the accessibility of the binding sites.