The efficiency of mechanochemical treatments in degrading pentachlorophenol (PCP) molecules in presence of the highly reactive phyllomanganate birnessite, and without using organic solvents, has been demonstrated in this study. By combining the information from solid-phase analyses with that from solvent extract analyses, and comparing the resulted data with those from previous batch-type experiments, it has been possible to get a comprehensive picture of the most reliable reaction mechanism of PCP molecules onto KBi surfaces. This allowed the individuation of specific sites in the synthesized oxides on which pentachlorophenol was preferentially adsorbed, and thus degraded. 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), as indicated by changes induced in the MnO6 layers of birnessite as a consequence of the prolonged milling with the pollutant. The mechanism implies reduction of Mn(IV), consequent formation of both Mn(III) and new vacancies, and release of free Mn2+ ions. This is quite low if compared to the formation of Mn(III). Therefore the cannibalization of the birnessite structure due to the redox reaction induced by mechanochemical treatments with PCP can be considered negligible. PCP mechanochemical degradation mainly occurs by dehalogenation.
Mechanochemical degradation of pentachlorophenol onto birnessite / Di Leo P.; Pizzigallo M.D.R.; Ancona V.; Di Benedetto F.; Mesto E.; Schingaro E.; Ventruti G.. - In: JOURNAL OF HAZARDOUS MATERIALS. - ISSN 0304-3894. - STAMPA. - 244-245:(2013), pp. 303-310. [10.1016/j.jhazmat.2012.11.037]
Mechanochemical degradation of pentachlorophenol onto birnessite
DI BENEDETTO, FRANCESCO;
2013
Abstract
The efficiency of mechanochemical treatments in degrading pentachlorophenol (PCP) molecules in presence of the highly reactive phyllomanganate birnessite, and without using organic solvents, has been demonstrated in this study. By combining the information from solid-phase analyses with that from solvent extract analyses, and comparing the resulted data with those from previous batch-type experiments, it has been possible to get a comprehensive picture of the most reliable reaction mechanism of PCP molecules onto KBi surfaces. This allowed the individuation of specific sites in the synthesized oxides on which pentachlorophenol was preferentially adsorbed, and thus degraded. 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), as indicated by changes induced in the MnO6 layers of birnessite as a consequence of the prolonged milling with the pollutant. The mechanism implies reduction of Mn(IV), consequent formation of both Mn(III) and new vacancies, and release of free Mn2+ ions. This is quite low if compared to the formation of Mn(III). Therefore the cannibalization of the birnessite structure due to the redox reaction induced by mechanochemical treatments with PCP can be considered negligible. PCP mechanochemical degradation mainly occurs by dehalogenation.File | Dimensione | Formato | |
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