title: Polyphenol-SiO2 hybrid biosorbent for heavy metal removal. Yerba mate waste (Ilex paraguariensis) as polyphenol source: kinetics and isotherm studies.
abstract: A low-cost biosorbent hybrid material ready for application was obtained in this work. Yerba mate (Ilex paraguariensis) milling residual dust was used as a polyphenol source by ethanolic extraction. Polyphenols were immobilized within a SiO(2) matrix to form an interpenetrated polymer after glutaraldehyde cross-linking. Pb(II), Cr(III) and Cr(VI) were chosen as model metals for adsorption. The hybrid materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Nitrogen Adsorption Isotherms. Adsorption experimental data were analysed using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Sips and Toth isotherm models along with the evaluation of adsorption energy and standard free energy (ΔG°). The adsorption was observed to be pH dependent. The main mechanism of metal adsorption was found to be a spontaneous charge associated interaction. Electron Spin Resonance (ESR) spectroscopy confirmed that Cr(VI) adsorption was an adsorption-coupled reaction and the adsorbed specie was Cr(V). The hybrid matrix probed its adsorption capacity of Cr(III) in a non-treated tannery wastewater.
authors.affiliation: Cátedra de Química Analítica Instrumental, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires (UBA), Junín 956, C1113AAD Buenos Aires, Argentina.
authors.forename: G J
authors.initials: GJ
authors.lastname: Copello
authors.forename: M P
authors.initials: MP
authors.lastname: Pesenti
authors.forename: M
authors.initials: M
authors.lastname: Raineri
authors.forename: A M
authors.initials: AM
authors.lastname: Mebert
authors.forename: L L
authors.initials: LL
authors.lastname: Piehl
authors.forename: E Rubin
authors.initials: ER
authors.lastname: de Celis
authors.forename: L E
authors.initials: LE
authors.lastname: Diaz
mesh_terms: D000327:Adsorption; D030019:Ilex paraguariensis / Q000737:chemistry*; D007700:Kinetics; D019216:Metals, Heavy / Q000737:chemistry* / Q000302:isolation & purification; D008855:Microscopy, Electron, Scanning; D059808:Polyphenols / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D019216:Metals, Heavy; D059808:Polyphenols; D012822:Silicon Dioxide