Electrostatic characterization of Al-modified, nanosized silica particles

2019-05-25 14:11:48

potential particles substitution Al zeta

责任者: Rasmusson, Mikael;Wall, Staffan 单位: Univ of Goteborg and Chalmers Univ of Technology, Goteborg, Sweden 来源出处: Colloids and Surfaces A: Physicochemical and Engineering Aspects,1997,122(1-3):169-181 摘要: Al-modified, nanosized silica particles have been studied with an electroacoustic technique. Also slightly aggregated silica particles have been investigated with this method. ζ-potentials calculated from the measured dynamic mobilities were found to be in good agreement with previous reported ζ-potentials obtained from streaming potential measurements. This indicates that the magnitude of the dynamic mobility is very similar to the electrophoretic mobility for moderately charged nanosized particles. The degree of Al-substitution was varied so that between 0 and 16% of the surface silicon atoms were replaced by aluminum. It was found that the magnitude of the titratable surface charge density increased with increasing degree of Al-substitution. This was especially pronounced in the neutral pH region. The behaviour of the ζ-potential as a function of Al-substitution was more complex than the behaviour of the surface charge density: increasing the degree of Al-substitution stepwise up to 7%, raised the magnitude of the ζ-potential both in 2 and 10 mM NaCl. A further increase of the degree of Al-substitution lead to a reduction of the magnitude of the ζ-potential. However, in 50 mM NaCl, it was favourable to include as much as 16% aluminum in the surface structure of the particle. The behaviour of the ζ-potential as a function of pH for the Al-modified samples can be explained in terms of adsorbed and non-adsorbed aluminum. 关键词: Silica;Particles (particulate matter);Aluminum;Acoustoelectric effects;Titration;Agglomeration;Chemical modification;Charged particles;pH effects;Adsorption;Electrostatics;Nanostructured materials;Colloids;Surface charge density;Dynamic mobility;Zeta potential