title: Description of mutual interactions between silicon and phosphorus in Andisols by mathematical and mechanistic models.
abstract: The Freundlich model and the Constant Capacitance Model (CCM) were used to describe silicon (Si) and phosphorus (P) sorption, both individually and for binary P-Si systems, on two Andisols with different chemical properties: Freire soil (FS) and Piedras Negras soil (PNS). Silicon sorption kinetics were examined through the Elovich equation, revealing that the initial sorption rate was 16 times greater in PNS. The Freundlich equation provides a good fit to the sorption data for both Andisols. When compared with FS, larger Si sorption capacity and lower Si affinity for the surface sites were observed in PNS; nevertheless, Si sorption decreased in both soils as P sorption increased. Slight reductions in P sorption capacity due to the presence of Si were found, whereas there was no apparent effect on P bonding intensity. The CCM was able to describe Si adsorption, and potentiometric titrations support that Si seems to be specifically sorbed mainly onto sites of negative charge. Comparable log KSiint values were obtained for both soils, indicating that Si was bound on similar sites. Phosphorus sorption was well described by the CCM, and log KPint denoted strong interactions of P with the surface sites. For binary systems, log KPint did not vary with increasing Si concentration; comparatively, log KSiint scarcely decreased with increasing P concentration in PNS, but a 28% reduction was found in FS at the highest initial P concentration.
authors.affiliation: Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Casilla 54-D, Temuco, Chile; Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Temuco, Chile. Electronic address: paula.cartes@ufrontera.cl.
authors.forename: Paula
authors.initials: P
authors.lastname: Cartes
authors.affiliation: Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Casilla 54-D, Temuco, Chile.
authors.forename: Mara
authors.initials: M
authors.lastname: Cea
authors.affiliation: Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Casilla 54-D, Temuco, Chile; Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Temuco, Chile.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Jara
authors.affiliation: Dipartimento di Agraria, Università Degli Studi di Napoli Federico II, Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Violante
authors.affiliation: Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Casilla 54-D, Temuco, Chile; Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Temuco, Chile.
authors.forename: María
authors.initials: M
authors.lastname: de la Luz Mora
mesh_terms: D000327:Adsorption; D007700:Kinetics; D008962:Models, Theoretical; D010758:Phosphorus / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus; D012825:Silicon
keywords: Andisol; Constant Capacitance Model; Freundlich equation; Phosphorus; Silicon; Sorption