title: Highly effective adsorption of heavy metal ions by a thiol-functionalized magnesium phyllosilicate clay.
abstract: A thiol-functionalized layered magnesium phyllosilicate material (called Mg-MTMS), prepared by a direct and cost-effective co-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 13C and 29Si 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 for the adsorption of Hg(II), Pb(II), and Cd(II) 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 (approximately 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 for the capture of metal ions is attributed to both 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.
authors.affiliation: Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, USA. Lagadic@okstate.edu
authors.forename: I L
authors.initials: IL
authors.lastname: Lagadic
authors.forename: M K
authors.initials: MK
authors.lastname: Mitchell
authors.forename: B D
authors.initials: BD
authors.lastname: Payne
mesh_terms: D000327:Adsorption; D002247:Carbon Isotopes; D007477:Ions; D017633:Magnesium Silicates / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D019216:Metals, Heavy / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002247:Carbon Isotopes; D007477:Ions; D017633:Magnesium Silicates; D019216:Metals, Heavy; D013438:Sulfhydryl Compounds; D014874:Water Pollutants, Chemical