Blute Irena, Pugh Robert J, van de Pas John, Callaghan Ian
YKI, Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden.
J Colloid Interface Sci. 2007 Sep 15;313(2):645-55. doi: 10.1016/j.jcis.2007.05.013. Epub 2007 May 13.
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.
对九种工业生产的粒径为5 - 40纳米的胶体二氧化硅分散体进行了表面表征和发泡研究。所有硅溶胶都产生了具有短衰减时间的瞬态泡沫，并且发现动态泡沫生成（发泡性）根据溶胶类型而变化，其中疏水性改性溶胶和去离子亲水性溶胶的发泡性最大。然而，发现通过将pH值改变到对应于最低亲水性区域的pH（pzc）范围内，可以实现所有溶胶发泡性的提高。pH值的增加（以及负电荷的积累）增强了表面亲水性并导致发泡性降低。此外，对于选定的亲水性溶胶，结果表明（a）发泡性随着粒径减小（在6 - 40纳米范围内）而增加，（b）发泡性随着颗粒浓度增加（在1 - 15重量％范围内）而增加。总体而言，得出的结论是，发泡性主要受疏水性（因此受pH值）控制，还受颗粒浓度、粒径和团聚程度控制。
