title: Complexation of ferric oxide particles with pectins of different charge density.
abstract: The effect of polyelectrolyte charge density on the electrical properties and stability of suspensions of oppositely charged oxide particles is followed by means of electro-optics and electrophoresis. Variations in the electro-optical effect and the electrophoretic mobility are examined at conditions where fully ionized pectins of different charge density adsorb onto particles with ionizable surfaces. The charge neutralization point coincides with the maximum of particle aggregation in all suspensions. We find that the concentration of polyelectrolyte, needed to neutralize the particle charge, decreases with increasing charge density of the pectin. The most highly charged pectin presents an exception to this order, which is explained with a reduction of the effective charge density of this pectin due to condensation of counterions. The presence of condensed counterions, remaining bound to the pectin during its adsorption on the particle surface, is proved by investigation of the frequency behavior of the electro-optical effect at charge reversal of the particle surface.
authors.affiliation: Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Milkova
authors.forename: Kamelia
authors.initials: K
authors.lastname: Kamburova
authors.forename: Ivana
authors.initials: I
authors.lastname: Petkanchin
authors.forename: Tsetska
authors.initials: T
authors.lastname: Radeva
mesh_terms: D000327:Adsorption; D004058:Diffusion; D004563:Electrochemistry / Q000379:methods; D004573:Electrolytes; D004586:Electrophoresis / Q000379:methods; D005290:Ferric Compounds / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry; D007477:Ions; D008956:Models, Chemical; D015233:Models, Statistical; D008970:Molecular Weight; D055095:Optics and Photonics; D010316:Particle Size; D010368:Pectins / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D005290:Ferric Compounds; D006603:Hexuronic Acids; D007477:Ions; C000499:ferric oxide; C007819:galacturonic acid; D010368:Pectins