FLOCCULATION OF MAGNESIUM HYDROXIDE BY ORGANIC HYBRIDS IN WATER AND WATER-SALT MEDIA
We have synthesized organic hybrids based on natural polysaccharides (pectin and starch) and cationic copolymer of acrylamide with dimethylaminoethyl methacrylate hydrochloride by mixing aqueous solutions of polymers under normal conditions without polymerization in optimal ratio of 1:3; 1:1 and 3:1. We also carried out a comparative analysis of the concentration and flocculation behavior of natural and synthetic polymers and organic hybrids on sedimentation process of a model disperse system - Mg(OH)<sub>2</sub> suspension in water and water-salt (NaCl) media in the free settling mode. The concentration of the synthetic polymer was an order of magnitude lower than that of the natural samples. We found the difference in the flocculating indexes of organic hybrids in water and water-salt media, caused by the influence of Na<sup>+</sup> and Cl<sup>-</sup> ions on the electro-surface properties of Mg(OH)<sub>2</sub> particles. At low starch concentrations in aqueous environment e observed the stabilization effect due to the anchoring mechanism of flocculation, and for the remaining polymer additives throughout the concentration range, the flocculating effect increases and a bridge mechanism is realized. According to sedimentation analysis, in systems with hybrid samples, an increase in flocculation capacity was observed compared with individual additives. By way of viscometric analysis, we evaluated the intermolecular interaction of pectin and cationic copolymer of acrylamide in water and water-salt solutions. We noted the low values of the F parameter in the aqueous medium, resulting from compression of macromolecular coils of the natural and synthetic polymers, approaching in their structure to globular formations. For the medium with I = 0.06 N, higher values are observed in comparison with the aqueous one, which indicates the weakening in it of the intermolecular macroions interactions intensity. When an inorganic salt (NaCl) is added to the solution, the charges are screened along the chain of macroions, which leads to a decrease in the electrostatic repulsive potential and a decrease in the value of the viscosity numbers.