Aggregation of Colloidal Particles in the Presence of Multivalent Co-Ions: The Inverse Schulze鈥揌ardy Rule

详细信息    查看全文

• 作者：Tianchi Cao ; Istvan Szilagyi ; Tamas Oncsik ; Michal Borkovec ; Gregor Trefalt
• 刊名：Langmuir
• 出版年：2015
• 出版时间：June 23, 2015
• 年：2015
• 卷：31
• 期：24
• 页码：6610-6614
• 全文大小：289K
• ISSN：1520-5827

文摘

Shifts of the critical coagulation concentration (CCC) in particle suspensions in salt solutions containing multivalent co-ions and monovalent counterions are rationalized. One observes that the CCC is inversely proportional to the valence, and this behavior is referred to as the inverse Schulze鈥揌ardy rule. This dependence is established by means of measurements of the stability ratio for positively and negatively charged latex particles with time-resolved light scattering. The same dependence is equally suggested by calculations of the CCC with the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, whereby the full Poisson鈥揃oltzmann equation for the asymmetric electrolytes has to be used. The latter aspect is essential, since in the case of multivalent co-ions the surface charge is principally neutralized by monovalent counterions. This rule complements the classical Schulze鈥揌ardy rule, which applies in the case of multivalent counterions, and states that the CCC is inversely proportional to the sixth power of the valence.