title: A functionalized phosphonate-rich organosilica layered hybrid material (PSLM) fabricated through a mild process for heavy metal uptake.
abstract: A phosphonate-rich organosilica layered hybrid material (PSLM) made of 3-(trihydroxysilyl)propyl methylphosphonate, monosodium salt, as the single silica source, has been obtained from its aqueous solution through a xerogel process and mild thermal aging. The method is simple, affording bulk quantities of powdered PSLM in a single-step. The hybrid is stable in water and possesses a high content of phosphonate groups fixed on the solid matrix. In addition, PSLM shows good thermal stability, which exceeds 300°C in air. The material was characterized using SEM, TEM, XRD, FT-IR and TGA techniques. Potentiometric titrations show that PSLM bears high-surface density of phosphonate groups (3 mmol g(-1)). As a result, the material displays high metal uptake capacity for heavy metal ions such as Cu(2+) (2.72mmolg(-1)), Pb(2+) (1.67 mmol g(-1)) and Cd(2+) (1.00 mmol g(-1)) at neutral pH values e.g. the pH of natural waters. Detailed theoretical modeling using a Surface Complexation Model combined with Electron Paramagnetic Resonance (EPR) spectroscopy shows that the surface distribution of surface bound Cu(2+) ions is rather homogeneous e.g. copper-binding phosphonate sites are arranged in average distances 5-8Å.
authors.affiliation: Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Chris
authors.initials: C
authors.lastname: Daikopoulos
authors.affiliation: Institute of Materials Science, NCSR "Demokritos", Ag. Paraskevi Attikis, Athens 15310, Greece.
authors.forename: Athanasios B
authors.initials: AB
authors.lastname: Bourlinos
authors.affiliation: Laboratory of Physical Chemistry, Department of Environmental and Natural Resources Management, University of Patras, Seferi 2, Agrinio 30100, Greece.
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Georgiou
authors.affiliation: Laboratory of Physical Chemistry, Department of Environmental and Natural Resources Management, University of Patras, Seferi 2, Agrinio 30100, Greece. Electronic address: ideligia@cc.uoi.gr.
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Deligiannakis
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry and Experimental Physics, Palacky University, Olomouc 77146, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Zboril
authors.affiliation: Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Karakassides
mesh_terms: D000327:Adsorption; D019216:Metals, Heavy / Q000737:chemistry*; D008962:Models, Theoretical; D063065:Organophosphonates / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D019216:Metals, Heavy; D063065:Organophosphonates; D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide
keywords: EPR; FITEQL; Layered hybrid; Phosphonates; Potentiometric titration; Surface complexation