Abstract
Simultaneous measurements of zeta (ζ) -potential and critical flocculation concentration (c.f.c.) s for two standard latex suspensions (Sample-A : Styrene/Nass copolymer latices, Sample-B : Amphoteric latices) were carried out so as to assess the reliability of each of these measurement techniques and find means for their improvement.
The ζ-potential measurements were carried out at nine laboratories using different electrophoretic apparatus, which included the Rank Brother M-2, PEN KEM-501, PEN KEM-3000 and Malvern Zetasizer-F. The data from all the laboratories showed fair agreement. Elevated potential supply was found to increase the slope of the ζ vs. pH curve near the isoelectric point of sample-B.
The c.f.cs. of KNO3, Mg (NO3) 2 and La (NO3) 3 for sample-A, were determined simultaneously by a static method and the results compared with those determined by a kinetic method and dynamic light scattering (L.S.). The order of the magnitude of the values of c.f.c. can be expressed as follows : static method < L.S. technique < kinetic method. Furthermore, it was found that in determining the c.f.c., the solid concentration in the medium was important factor.
