ELECTRIC LIGHT-SCATTERING OF FERRIC-OXIDE PARTICLES IN SODIUM CARBOXYMETHYLCELLULOSE SOLUTIONS

The electric light scattering of aqueous oxide suspension in the prese nce of sodium carboxymethylcellulose (Na-CMC) was investigated. The el ectro-optical effect in the kilohertz frequency range was found to dec rease because of the polyelectrolyte adsorption, contrary to the stron g increase of the effect in the range of particles rotation (at hertz frequencies). The counterion mobility decrease due to condensation in the polyelectrolyte vicinity was supposed to be responsible for the re laxation frequency shift of the effect to the low-frequency side. The addition of salts (NaCl and CaCl2) to the stabilized suspensions was s hown to change the ratio of high frequency to low frequency effects-th e first one was seen to increase in contrast to the second. In the pre sence of salts, the polyelectrolyte charge shielding and counterions m obility increase were found to be different for monovalent and divalen t ions, which could be attributed to the specific interaction of Ca2with Na-CMC. (C) 1995 Academic Press, Inc.