title: Mechanochemical transformation of an organic ligand on mineral surfaces: the efficiency of birnessite in catechol degradation.
abstract: The aim of this work is to investigate the efficiency of the phyllomanganate birnessite in degrading catechol after mechanochemical treatments. A synthesized birnessite and the organic molecule were grounded together in a high energy mill and the xenobiotic-mineral surface reactions induced by the grinding treatment have been investigated by means of X-ray powder diffraction, X-ray fluorescence, thermal analysis and spectroscopic techniques as well as high-performance liquid chromatography and voltammetric techniques. If compared to the simple contact between the birnessite and the organic molecule, mechanochemical treatments have revealed to be highly efficient in degrading catechol molecules, in terms both of time and extent. Due to the two phenolic groups of catechol and the small steric hindrance of the molecule, the extent of the mechanochemically induced degradation of catechol onto birnessite surfaces is quite high. The degradation mechanism mainly occurs via a redox reaction. It implies the formation of a surface bidentate inner-sphere complex between the phenolic group of the organic molecules and the Mn(IV) from the birnessite structure. Structural changes occur on the MnO(6) layers of birnessite as due to the mechanically induced surface reactions: reduction of Mn(IV), consequent formation of Mn(III) and new vacancies, and free Mn(2+) ions production.
authors.affiliation: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, C.da S. Loja, Zona Industriale, 85050 Tito Scalo (PZ), Italy. pdileo@imaa.cnr.it
authors.forename: Paola
authors.initials: P
authors.lastname: Di Leo
authors.forename: Maria Donata Rosa
authors.initials: MD
authors.lastname: Pizzigallo
authors.forename: Valeria
authors.initials: V
authors.lastname: Ancona
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Benedetto
authors.forename: Ernesto
authors.initials: E
authors.lastname: Mesto
authors.forename: Emanuela
authors.initials: E
authors.lastname: Schingaro
authors.forename: Gennaro
authors.initials: G
authors.lastname: Ventruti
mesh_terms: D002396:Catechols / Q000302:isolation & purification*; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D004055:Differential Thermal Analysis; D004785:Environmental Pollutants / Q000302:isolation & purification*; D052918:Environmental Restoration and Remediation / Q000379:methods; D055595:Mechanical Phenomena; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D012037:Refuse Disposal / Q000379:methods*; D013499:Surface Properties; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D002396:Catechols; D004785:Environmental Pollutants; D010087:Oxides; C505018:birnessite; C034221:catechol