Conference paper

On the Reiation between Surface Charge and Sol Stability

J. Lyklema ; Laboratory for Physical and Colloid Chemistry of the Agricultural University, De Dreijen 6, Wageningen, The Netherlands

Abstract

This paper discusses . various charges distinguishable in electrical
double layers, namely the electrokinetic charge oek• the Stern
charge om and the surface charge 00 • The electrokinetic charge cain
be calculated from the electrokinetic potential t The approximation
'IJJct = ~ appears to work well for the AgI-system. Hence, oek - od,
the diffuse double layer charge. The potential 'IJJct is the determining
quantity in colloidal stability. Concersely, from stability measurements
'i'ct and hence od can be evaluated. The surface charge
0 0 can in most cases also be determined experimentally. Its relation
to od, and hence to sol stability, is indirect. Because of the balance
ad + om + 0 0 = 0, the Stern charge can be found from 0 0 and
od by subtraction. This i·s the relatively most informative quantity.
Two example are worked out for the AgI-sistem, the lyotropic
sequence (om (Li+) < om (K+) < om (Rb+)) and the effect of different
alcohols on om. In the latter case it is found that butanol tends to
desorb cations, whereas ethylene glycol has only a neglegible effect
on the cation binding.

Keywords

Hrčak ID:

196446

URI

https://hrcak.srce.hr/196446

Publication date:

22.12.1976.

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