English   español  
Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/52156
Compartir / Impacto:
Estadísticas
Add this article to your Mendeley library MendeleyBASE
Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Título

31P NMR spectroscopic studies of the influence of the environment in the degradation process of the Graham's salt

AutorCasas, José M. ; García, María Pilar ; Sanz, Manuel; Cacho, Francisco; Pérez, Jorge
Fecha de publicación2010
EditorElsevier
CitaciónCeramics International 36(1): 39-46 (2010)
ResumenThe >Graham's salt> is a vitreous sodium polyphosphate with a general formula of Na(n+2)PnO(3n+1). It is used in the ceramics industry as a deflocculant additive in a matrix of sodium silicate with different SiO2:Na2O ratios. The influence of the environment in which the Graham's salt is usually placed on its degradation into smaller particles has been studied by 31P NMR spectroscopy at several temperatures on solutions with 7% of Graham's salt in sodium silicate with Rw = 1.6, 2.0, 3.3, in sodium carbonate 0.15 M, in sodium hydroxide 0.10 M and 1.0 M and in water. The signals in the 31P NMR spectra of Graham's salt in D2O, depending on their chemical shift δ (ppm) and multiplicity, have been assigned to the different phosphorous atoms of the skeleton of the several polyphosphates that are present in the solution. The integration of these signals at different temperatures has enabled the collection of kinetic and thermodynamic data: kinetic constants k (s-1), activation energy Ea, ΔH‡ and ΔS‡. Results indicate that the environment is a factor which favours the degradation of polyphosphates, since with increasing basicity of deflocculating solutions the rate of degradation is faster. White gel obtained as a final product of the degradation process of Graham's salt has been analyzed with 31P NMR spectroscopic measurements identifying orthophosphate and pyrophosphate as the main final species of the degradation of Graham's salt. © 2009 Elsevier Ltd and Techna Group S.r.l.
URIhttp://hdl.handle.net/10261/52156
DOI10.1016/j.ceramint.2009.06.028
Identificadoresdoi: 10.1016/j.ceramint.2009.06.028
issn: 0272-8842
Aparece en las colecciones: (ICMA) Artículos
Ficheros en este ítem:
Fichero Descripción Tamaño Formato  
accesoRestringido.pdf15,38 kBAdobe PDFVista previa
Visualizar/Abrir
Mostrar el registro completo
 

Artículos relacionados:


NOTA: Los ítems de Digital.CSIC están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.