Flocculation of a suspension of quartz in the presence of super flocculants of different charge

Abstract

The influence of cationic and anionic superprocesses and their binary mixtures on the degree of aggregation and the charge of particles of a suspension of quartz. Varied the amount entered in the suspension of the specified reagents, the charge density of the flocculants, the order of introduction of mixture components in the system. The addition of anionic flocculant causes a twofold increase in the potential due to adsorption of negatively charged ions of polymer segments on the negatively charged surface of quartz particles due to non-Coulomb forces. It is shown that the addition of cationic flocculant leads to a significant decrease in the negative values of the particles and a change in the sign of their charge.  In the presence of mixtures of anionic and cationic flocculants, regardless of their composition and the order of introduction of the components into the suspension, the particles acquire a negative potential characteristic of the particles adsorbing only anionic flocculant. With an increase in the amount of the added mixture, the flocculation rate and the size of the resulting floccules increase, while a further increase in the concentration of these mixtures causes a decrease in the size of the aggregates. For mixtures of charged anionic and cationic flocculants, the synergism of flocculant action is observed. This effect was observed even for mixtures with multiple excess of negatively charged segments compared to positively charged ones. The observed regularities are explained by the peculiarities of the structure of adsorption layers of flocculant mixtures by the coexistence of a thin layer of adsorbed cationic polymer chains with a large number of contacts with the surface and an extended layer of anionic flocculant (long loops and tails of macromolecules), in which a layer of cationic polymer is “hidden”. The electrokinetic potential and the ability of particles to aggregate (by the mechanism of formation of polymer bridges) in solutions of mixtures of anionic and cationic polyelectrolytes is determined, first of all, by the adsorption value of anionic polymer.