The use of the contact angle as a criterion for the degree of hydrophobization of a solid surface and gypsum particles in suspensions containing surfactants showed that an increase in the concentrations of ethyl silicone oil and soap naphtha in the initial gypsum suspensions led to an increase in the contact angle of wetting of solid particles to 82.5° and 77.5°, respectively. However, on the surfaces of the formed solid samples containing ethyl silicone oil, a drop of water spreading and its rapid absorption were observed. Solid samples containing soap naphtha in an amount of 3% had a hydrophobic surface characterized by a contact angle of 82.2°. Probably, the hydrophilic and hydrophobic properties of the solid surface of the material are determined by its bulk structure at the stage of formation, including under wave action. In this case, the porous-capillary structure of the formed samples containing gypsum and surfactants affects the determination of the wetting criterion.

Keywords: contact angle, hydrophobization, gypsum, soap naphtha, ethyl silicone oil, ultrasonic treatment

The analysis of ultrasonic effect on mixing solutions and hydrophobization of solid phase in suspensions for construction purposes is carried out. It is shown that ultrasonic treatment leads to an increase in the mass content of particles with a radius of 2-7 μm in the mixing solution, which contributes to an increase in the relative tensile strength of the samples obtained on its basis. Ultrasonic treatment of suspensions with the same relative degree of hydrophobization of the solid surface led to different contact angles of wetting of solid particles: Ө = 120, 450, 930, 69.40 for clay, cement and silica particles. Ultrasound leads to a significant decrease in the volume fraction of liquid in a three-phase foam stabilized by hydrophobized clay particles, compared to the syneresis process in a gravitational field.

Keywords: three-phase foam, silica suspension, clay, ultrasound, mixing solution

The effect of organomodified silica particles on the extraction of dissolved diesel fuel from water was studied. The dependence of the efficiency of water purification on the concentration and type of solid particles, as well as the concentration and type of surfactant, is shown. When using a short-chain surfactant to modify the surface of silica particles, the minimum residual concentration of diesel fuel was 2.71 mg/l at a concentration of 4% Aerosil-380 and hexylamine 57 mmol/l. Replacing the short-chain surfactant hexylamine with the long-chain CTAMB led to an 8% improvement in the quality of water purification due to an increase in the surface activity of the organic cation. The use of modified clay particles to purify water from diesel fuel showed lower efficiency compared to Aerosil-380 particles at similar concentrations of the solid phase and surfactant modifier.

Keywords: Pickering foam, foam emulsion, diesel fuel, water purification, silica, cationic surfactant, hexylamine, cetyltrimethylammonium bromide

The stability of three-phase foams stabilized by particles and surfactants (surfactants) of various nature has been studied. The varying degree of hydrophobization of particles by short-chain surfactant hexylamine may be accompanied by a change in the properties of the dispersed system from high-strength and low-stability foams to structured low multiplicity. A decrease in the stability of foams stabilized by hydrophobized titanium oxide particles at a concentration of long-chain surfactant - cetylammonium bromide Cпав≥Сккм may be due to a decrease in the edge angle of wetting of solid particles.

Keywords: foams, solid particles, surfactants, stability