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Keywords: coagulation

Colloidal protection of magnetite hydrosols with polysaccharides

https://doi.org/10.58224/2619-0575-2025-8-3-2
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Abstract
This article investigates the stabilization of aqueous dispersions of magnetic Fe₃O₄ nanoparticles using polysaccharide stabilizers. The effect of electrolyte coagulants and polysaccharide stabilizers on the stability of magnetite hydrosols and their stability at physiological pH with and without the addition of polysaccharides is stud-ied. The results demonstrate the effectiveness of nonionic polysaccharides, such as hydroxypropyl methylcellulose and hydroxyethylcellulose, in stabilizing magnetic nanoparticles from electrolyte coagulation and over time, which is important for their application in medicine.
Objectives. To obtain and characterize magnetite hydrosols and to study their stabilization with polysaccharides over time and with the addition of non-indifferent and indifferent electrolytes.
Methods. Hydrosol coagulation was studied photometrically. The size of hydrosol nanoparticles was determined using dynamic light scattering.
Results. Nonionic polysaccharides, such as hydroxyethyl cellulose and hydroxypropyl methylcellulose, are promising for stabilizing aqueous dispersions (hydrosols) of Fe3O4 magnetic nanoparticles.
Conclusions. The coagulation threshold of magnetite hydrosol with a non-differentiated electrolyte, sodium hy-droxide, is 20,5 times lower than the coagulation threshold of magnetite hydrosol with an indifferent electrolyte, sodium chloride. Hydroxyethyl cellulose and hydroxypropyl methylcellulose exhibited the greatest protection of magnetite hydrosol from coagulation with sodium chloride. Hydroxypropyl methylcellulose exhibited the greatest protection of magnetite hydrosol from coagulation with sodium hydroxide. Sols containing hydroxypropyl methyl-cellulose exhibit the greatest stability over time at pH 7.4 (the pH of blood), created by the addition of a phosphate-buffered saline mixture.
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Adsorption of kappa-carrageenan on the surface of chitosan and its sulfuric acid salt and stabilization of chitosan-sulfate nanoparticles by it

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 5-18 p.
Abstract
Objectives: to investigate the adsorption of k-carrageenan on the surface of chitosan at pH 7.4 and chitosan treated with dilute sulfuric acid solution (pH 2.5-2.7). To develop a method for obtaining the sol of the chitosan sulfate salt - chitosan sulfate (CX) and to investigate its stability in time depending on the use of various acids as precursors, and its increase with the addition of different concentrations of k–carrageenan.
Methods. To determine the viscosity of polymer solutions, their molecular weight and to study the adsorption of k-carrageenan on CX, the method of capillary viscometry was used. The assessment of the stability of the zones over time was carried out photometrically.
Results. The adsorption of k-carrageenan on chitosan and CX has been studied: experimental isotherms of k-carrageenan adsorption have been constructed.on the surfaces of chitosan and CX, the constants of the Langmuir equation are calculated and complete theoretical adsorption isotherms are constructed using them. A method for obtaining a CX hydrosol with a positive particle charge has been developed. The stability of CX sols in time both without additives and with additives of k-carrageenan in time has been studied.
Conclusions. The adsorption of k-carrageenan on chitosan and CX is monomolecular. The adsorption equilibrium constant is greater with the adsorption of k-carrageenan on the surface of CX, and the maximum adsorption value is greater with the adsorption on the surface of chitosan. Of the acids used as precursors, the sol obtained using citric acid has the greatest stability. With an additional additive to the sols of the protective colloid - k-carrageenan to sols obtained using hydrochloric acid and citric acid, the sol obtained with the use of hydrochloric acid and carrageenan additives in the range of 0.04-0.06% has the greatest aggregate stability.
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INTENSIFICATION OF THE COAGULATING SUSPENSION EFFECT ON THE EMULSION OF LIPID CONCENTRATE IN WATER

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 77-85 p.
Abstract
The coagulation treatment method is widely used for the effluents of various origins treatment. Substances-coagulants disrupt colloidal formations and contribute to the small particles aggregation, which leads to their precipitation and, as a consequence, a decrease in the organic substances content and the solution turbidity. The most widely used for this purpose are coagulants based on iron and aluminum. The Hermetia illucens insect is increasingly used to obtain chemical raw materials and valuable feed products for the poultry and fish cultivation. Production processes generate effluents contaminated with biodegradable substances, including components of larval fat. In this work, it was studied the coagulation purification possibility of fat-containing effluents from the production of lipid concentrate from the Hermetia illucens fly larvae by a coagulating suspension obtained from the electric arc steel-making furnaces dust, together with a co-coagulant – chestnut leaves carbonized at 400° C, which were used to increase the number of coagulation centers in the system.
The use of a coagulating suspension in the purification of model emulsions gives a low clarification effect (49% with the addition of 0.2 cm3 per 100 cm3 of the emulsion). It was found that the addition of finely dispersed carbon-ized leaves can significantly increase the cleaning efficiency. The best result was obtained by adding the carbonized chestnut leaves in an amount of 0.3 g together with 0.2 cm3 of suspension per 100 cm3 of liquid, while the clarification efficiency of the lipid concentrate model emulsion was 98%, at a pH of 8.
The main stage of coagulation occurs in the first 40 minutes of interaction, after which no changes are observed in the state of the system under study.
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