title: Mechanochemical degradation of pentachlorophenol onto birnessite.
abstract: The existence of a lot of worldwide pentachlorophenol-contaminated sites has induced scientists to concentrate their effort in finding ways to degrade it. Therefore, an effective tool to decompose it from soil mixtures is needed. In this work the efficiency of the phyllomanganate birnessite (KBi) in degrading pentachlorophenol (PCP) through mechanochemical treatments was investigated. To this purpose, a synthesized birnessite and the pollutant were ground together in a high energy mill. The ground KBi-PCP mixtures and the liquid extracts were analyzed to demonstrate that mechanochemical treatments are more efficient in removing PCP than a simple contact between the synthesized birnessite and the pollutant, both in terms of time and extent. The mechanochemically induced PCP degradation mainly occurs through the formation of a surface monodentate inner-sphere complex between the phenolic group of the organic molecules and the structural Mn(IV). This is indicated by the changes induced in birnessite MnO(6) layers as a consequence of the prolonged milling with the pollutant. This mechanism includes the Mn(IV) reduction, the consequent formation of Mn(III) and new vacancies, and free Mn(2+) ions release. The PCP degradation extent is limited by the presence of chloro-substituents on the aromatic ring.
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 R
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: D002384:Catalysis; D010087:Oxides / Q000737:chemistry*; D010416:Pentachlorophenol / Q000737:chemistry*; D033362:Powder Diffraction; D012989:Soil Pollutants / Q000737:chemistry*; D018505:Waste Management / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D010087:Oxides; D012989:Soil Pollutants; C505018:birnessite; D010416:Pentachlorophenol