Silica nanoparticle sols 1: Surface chemical characterization and evaluation of the foam generation (foamability)
2007 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 313, no 2, 645-655 p.Article in journal (Refereed) Published
Surface characterization and foaming studies were carried out with nine industrially manufactured, colloidal silica dispersions with particles sizes from 5-40 nm. All the silica sols produced transient foams with short decay times and the dynamic foam generation (foamability) was found to vary according to the sol type with the greatest foamability occurring for the hydrophobically modified sol and the deionized hydrophilic sol. However, it was found that improved foamability of all the sols could be achieved by changing the pH to within the region of the pH(pzc) which corresponds to the region of lowest hydrophilicity. An increase in pH (and build-up of negative charge) enhances the surface hydrophilicity and caused a decrease in foamability. In addition, for selected hydrophilic sols, it was shown that the foamability (a) increased with decrease in particle size (within the 6-40 nm range) and (b) increased with particle concentration (within the range of 1-15 wt%). Overall, it was concluded that the foamability was primary controlled by hydrophobicity (and hence by pH) and also by the particle concentration, the particle size and the degree of agglomeration.
Place, publisher, year, edition, pages
2007. Vol. 313, no 2, 645-655 p.
colloidal silica, foamability, foams, nanoparticles, surface charge, ultrasound, light scattering, kinematic viscosity
IdentifiersURN: urn:nbn:se:kth:diva-36034DOI: 10.1016/j.jcis.2007.05.013ISI: 000248766000032ScopusID: 2-s2.0-34547232593OAI: oai:DiVA.org:kth-36034DiVA: diva2:430213
QC 201107072011-07-072011-07-062011-07-07Bibliographically approved