Irreversible versus reversible aggregation : Mean fiel theory and experiments.

Dublin Core

Título

Irreversible versus reversible aggregation : Mean fiel theory and experiments.

Tema

COLOIDES
CINETICA
BIBLIOGRAFIA NACIONAL QUIMICA
2004

Abstract

Colloidalaggregation processes arising at different electrolyte concentrations were studied by means of experiments and confronted with theoretical predictions of different kinetic aggregationmodels. For this purpose, aqueous dispersions of relatively large polystyrene microspheres were chosen as experimental systems.Aggregation was induced by adding KBr electrolyte to the initially stable particle dispersions. During the aggregation processes, the cluster-size distribution was monitored by means of single cluster light scattering. Analyzing the time evolution of the monomer concentration, we found that the processes arising even at moderate electrolyte concentrations cannot be described by pure time-independent irreversible aggregationmodels. Hence, alternative models such as time-dependent irreversible aggregation and several reversible aggregationmodels were also tested. The model that considers a time-dependent sticking probability was found to fit the data quite satisfactorily. Nevertheless, the fitted was so slow that it seems not very likely to find such a behavior in real systems. The aggregation-fragmentation models reported in the literature were unable to reproduce the experimental observations. Hence, a more realistic reversible aggregationmodel was developed. This model accounts also for reenforced or double bonds between the constituent particles. The corresponding fit improved significantly and reached the same quality as the time-dependent model. Moreover, the obtained fitting parameters were in qualitative agreement with the DLVO predictions and so, reversible aggregation seems to be a more reasonable explanation for the experimental data than time-dependent irreversible aggregation. However, no definite statement on the possible secondary bond fragmentation mechanism may be made since both the applied shear stress in the measuring cell and thermal fluctuations can cause weaker bonds to break.

Autor

Odriozola, G
Leone, R
Schmitt, A
Callejas-Fernández, J
Martínez-García, R
Hidalgo-Alvarez, R

Fuente

Journal of Chemical Physics v. 121, no. 11, 2004. -- p. 5468-5481

Editor

American Institute of Physics

Fecha

2004

Derechos

Información sobre Derechos de Autor

(Por favor lea este aviso antes de abrir los documentos u objetos)

La legislación uruguaya protege el derecho de autor sobre toda creación literaria, científica o artística, tanto en lo que tiene que ver con sus derechos morales, como en lo referente a los derechos patrimoniales con sujeción a lo establecido por el derecho común y las siguientes leyes

(LEY 9.739 DE 17 DE DICIEMBRE DE 1937 SOBRE PROPIEDAD LITERARIA Y ARTISTICA CON LAS MODIFICACIONES INTRODUCIDAS POR LA LEY DE DERECHO DE AUTOR Y DERECHOS CONEXOS No. 17.616 DE 10 DE ENERO DE 2003, LEY 17.805 DE 26 DE AGOSTO DE 2004, LEY 18.046 DE 24 DE OCTUBRE DE 2006 LEY 18.046 DE 24 DE OCTUBRE DE 2006)

ADVERTENCIA - La consulta de este documento queda condicionada a la aceptación de las siguientes condiciones de uso: Este documento es únicamente para usos privados enmarcados en actividades de investigación y docencia. No se autoriza su reproducción con fines de lucro. Esta reserva de derechos afecta tanto los datos del documento como a sus contenidos. En la utilización o cita de partes debe indicarse el nombre de la persona autora.

Formato

PDF

Idioma

Inglés

Tipo

Artículo

Identificador

doi.org/10.1063/1.1779571

Document Item Type Metadata

Original Format

PDF
Fecha de agregación
April 21, 2015
Colección
Bibliografía Nacional Química
Tipo de Elemento
Document
Etiquetas
,
Citación
Odriozola, G, “Irreversible versus reversible aggregation : Mean fiel theory and experiments.,” RIQUIM - Repositorio Institucional de la Facultad de Química - UdelaR, accessed June 4, 2020, http://riquim.fq.edu.uy/items/show/2833.
Archivos