Rheological properties and concentration cross-overs of anionic acrylamide copolymers in saline solutions (potassium chloride) were investigated by using capillary viscometer method. Area of non-overlapping coils between the crossover concentration and the concentration of fluctuation mesh formation was determined; it was shown that with increase of salt concentration this area practically disappears, i.e. mass transfer mechanism changes near the crossover concentration. It was shown that at low concentrations of potassium chloride increasing the content of ionic groups of macromolecules leads to reduction in the crossover concentration and increase in the effective volume. It is found that the kaolin adsorption capacity decreases when polymers are adsorbed from saline solution, and the adsorption constant is significantly higher in the presence of salt than in water.
Copolymers of methacrylic acid and natural terpene monomers (α-pinene; β-pinene; ∆3-karene) with the molecular weight of (0.3–0.5)∙104 and a content of carboxyl groups of 14.5–16.3 % were synthesized. For the synthesized copolymers, hydrodynamic radius and the Kuhn segment, which characterizes flexibility of a polymer chain, were determined, as well as the Huggins constant in aqueous and saline solutions, and concentration regions for formation of supramolecular structures. In the presence of a cationic surfactant (benzetonium chloride, Hyamine), depending on the concentration of copolymers in the system, polymer-surfactant complexes were formed in soluble and insoluble forms. It has been shown that the effectiveness of the stabilizing action of soluble complexes with respect to an aqueous dispersion of calcium carbonate increases with an increase in the content of nonpolar groups in the polymer chain. A cationic surfactant (Hyamine) has been proposed as a precipitant in the method for the quantitative determination of carboxyl-containing polymers in aqueous and saline media.
A cationic flocculant with an amide-type polymer matrix was synthesized by modifying polyacrylamide according to the Mannich reaction. The use of a modified polymer leads to an increase in the adsorption of the polymer on solid phase particles in an aqueous dispersion of kaolin, an increase in the rate of kaolin sedimentation by a factor of 1.2–1.4, and makes it possible to expand the concentration range of dispersion destabilization compared to polyacrylamide.
Аннотация. Показано, что устойчивость водной и солевой дисперсии каолина уменьшается при введении катионного полиэлектролита и его смесей с поверхностно-активным веществом. Флокулирующая способность катионного полиэлектролита уменьшается с ростом содержания ионогенных групп. Установлено увеличение флокуляции в солевой среде при введении смеси полиэлектролита с анионным ПАВ, а также при последовательном добавлении компонентов в дисперсию каолина. Ключевые слова: дисперсные системы, полиэлектролит, флокуляция, поверхностно-активные вещества, агрегативная устойчивость Для цитирования. Влияние полиэлектролитов и поверхностно-активных веществ на устойчивость микрогетерогенных систем / П. Д. Воробьев [и др.] // Вес. Нац. акад. навук Беларусi.
The conditions and the patterns of copper and nickel nanoparticles formation by direct reduction from aqueous solutions of their salts in nitrogen atmosphere were studied, and nanocomposite materials based on magnesium oxide and metal nanoparticles coated with protective oxide shell were obtained. The obtained materials are of interest as sorbents for the purification of aqueous media from toxic impurities, as well as catalysts in organic synthesis, in particular for the production of methanol from carbon dioxide. Phase composition, thermal stability, microstructure of nanocomposites, as well as their sorption properties, were studied. The powders of magnesium oxide and nanocomposites based on it were found to have high sorption capacities with respect to lead and chromium ions – up to 2989.0 and 499.9 mg/g, respectively.
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