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Adsorbimento e desorbimento del Ni(II) in un terreno calcareo mediante la tecnica del flusso continuo (stir-flow) - XXIII Convegno Nazionale della Società Italiana di Chimica Agraria
No full textSpeciazione dei metalli pesanti in un terreno antropogenico di copertura di una discarica controllata.
No full textEffetto di alcuni componenti della frazione colloidale del suolo sulla ritenzione del piombo- Volume dei Riassunti dei Contributi Scientifici del XX Convegno Nazionale della Società Italiana di Chimica Agraria, Padova, 24-27 settembre, p. 116
No full textSorption Mechanisms Determining Ni(II) Retention by a Calcareous Soil
No full textThe objective of the study was to determine the mechanisms of Ni retention in a calcareous soil by comparing the sorption kinetics and adsorption-desorption isotherms of the whole soil and of some of its fractions. The study was performed using diffiractometric, microscopic, and thermogravimetric techniques to corroborate the mechanisms hypothesized from the equilibrium and kinetic studies. The sorption kinetics and the adsorption-desorption isotherms show that in a calcareous soil, Ni(II) is also retained by carbonates. In addition to the well known insolubilization process as a hydroxide caused by the high pH value induced by the presence of carbonates, calcium carbonate also contributes to Ni retention through the formation of a strong complex probably ascribable to a co-precipitation process that involves Ni/Ca carbonate double salt or mixed Ni/Al hydroxides and carbonates formation. The study also demonstrates that montmorillonite and illite clays may contribute to the adsorption of Ni with a nonspecific ion exchange mechanism, but as the Ni retention in the calcareous soil is totally specific, it can be presumed that this clay sorption mechanism is totally overshadowed by the double effect (Ni precipitation and complexation) caused by CaCO3
Rinaturalizzazione mediante l'impiego di compost da RSU di un terreno antropogenico di copertura di una discarica controllata
No full textEffetto dell'ammendamento con materiali organici di scarto sul destino degli xenobiotici nel suolo
No full textMechanisms of Pb(II) sorption and desorption at some clays and goethyte-water interfaces
No full textThe aim of this research is to corroborate the results obtained with Pb (II) sorption and desorption macroscopic equilibrium studies on some soil minerals (montmorillonite, illite, kaolinite and goethite) using microscopic techniques. The sorption isotherms demonstrate that the adsorption capability of the substrates varies in the following sequence: illite > montmorillonite > kaolinite > goethite, and the desorption isotherms demonstrate the irreversibility of the bonds formed. pH adsorption edges on montmorillonite show that at a pH lower than the hydrolysis point the sorption edge is primarily due to ion exchange, while at a pH higher than the hydrolysis point, it is a combination of both ion exchange and precipitation. The EDS semi-quantitative analysis performed by SEM demonstrates that in the clays Pb replaced almost exclusively Ca ions. In the montmorillonite this replacement may also include the Ca ions in the interlayer space, and in the illite also, the replacement of protonated OH groups and the K ions situated at the edge of interlattice sites. Goethite shows an adsorption capability of the same magnitude as kaolinite
Acidi umici da suolo e da compost e loro complessi con il piombo analizzati in spettroscopia infrarossa, spettroscopia di fluorescenza e calorimetria a scansione differenziale
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