Concentration Dependence of the Surface Tension of Three and Four-Component Systems with Peculiarities in the Surface Tension Isotherms of Lateral Binary Melts

The experimental study results of the melts concentration dependence of the surface tension of the four-component indium-tin-lead-bismuth system and its constituent binary systems of indium-tin, indium-lead, indium-bismuth, tin-lead, tin-bismuth, lead-bismuth are presented in the paper. It is shown that the concentration dependence of the melts surface tension of the In-Sn-Pb-Bi four-component system can be predicted from the data on ST (surface tension) values of lateral binary systems. Features in the ST isotherms in the form of a minimum are observed only in the indium-tin lateral system from all lateral binaries. A distinctive feature of the detected minimum is that the minimum depth slightly exceeds the experimental error. Therefore, in addition to the fact that the area of average compositions was studied more thoroughly, we carried out the surface tension measurements by two independent methods. The experimental data obtained by both methods coincide within the experimental error and indicate the extremum availability on ST isotherms. Thus, ST experimental studies by two independent methods confirmed the presence of a flat minimum on ST isotherms of the indium-tin binary system increasing the reliability of the obtained data. The obtained outcomes and their comparison with experimental data have shown that the considered models for predicting surface properties based on data due to similar properties of lateral binary systems adequately reflect the experimental dependences. However, the prediction model based on Kohler's method of excess values describes the experimental curves more accurately.

The Effect of Particle Sizes on the Concentration Dependence of the Surface Tension of Aqueous Suspensions of Bentonite

The paper presents experimental results on the dependence of surface tension on the concentration of a suspension of bentonite (0 - 10% by weight). The isotherms σ of aqueous suspensions of bentonite are characterized by local minima in the concentration range of 3-4 mass% of the solid phase. It has been established that a decrease in the average particle size leads to the disappearance of the extremum on the surface tension isotherms. The data obtained led to the conclusion that the most important factors affecting the nature of the isotherms of the surface tension of bentonite suspensions are the degree of dispersion and the presence in the aqueous suspension of bentonite, both colloidal and coarse particles.

ПОВЕРХНОСТНОЕ НАТЯЖЕНИЕ СМЕСЕЙ ПОЛИАКРИЛАМИДА С НЕИОННЫМИ ПОВЕРХНОСТНО-АКТИВНЫМИ ВЕЩЕСТВАМИ (SURFACE TENSION OF MIXTURES OF POLYACRYLAMIDE WITH NON-IONIC SURFACE-ACTIVE SUBSTANCES)

The aim of this work is to study the surface properties of mixtures of polyacrylamide (PAA) with nonionic surfactants. In this work, kinetic curves of a decrease in the surface tension of PAA were obtained in the concentration range of 1 * 10-5 ÷ 1 * 10-3 base mol/l, and on the basis of the equilibrium values of surface tension, isotherms of the surface tension of aqueous solutions of composite mixtures based on polyacrylamide (PAA) were obtained with surfactants - nonionic amphoteric N, N – dimethyldodecylamine N-oxide (DMDAO) and nonionic cocoamidopropyl betaine (CAPB). It has been shown that compositions of surfactant with a polymer in the region of low concentrations have a lower surface tension, which is associated with an increase in the surface activity of surfactant - PAA composites in comparison with individual surfactants. The surface tension isotherms were used to determine the critical micelle concentration (CMC) of the surfactant and surfactant-PAA compositions. It was found that the addition of a polymer to a surfactant lowers the CMC by an order of magnitude for the DMDAO - PAA mixture and by more than two orders of magnitude for the CAPB - PAA mixture, which also indicates an increase in the surface activity of the surfactant - polymer mixtures. The use of PAA compositions with surfactants as stabilizers for foams and emulsions opens up prospects for the development of effective emulsifiers and foaming agents.

Experimental Procedure for the Determination of the Critical Coalescence Concentration (CCC) of Simple Frothers

In this study, the critical coalescence concentrations (CCC) of selected commercial frother solutions, namely polypropylene glycols (PPG 200, 400, and 600), tri propylene glycol (BTPG), triethylene glycol (BTEG), dipropylene glycol (BDPG), and as a reference, methyl isobutyl carbinol (MIBC), were determined using a bubble column based on light absorption. The results for all seven frothers showed that BTEG has the worst bubble inhibiting performance, and PPG 600 has the best bubble inhibiting performance. While critical coalescence concentration (CCC) was found as 3 ppm for PPG 600, it increased to 25 ppm for BTEG. In the case of MIBC, which was the reference point, the CCC value was found as 10 ppm, which was consistent with the literature. The surface tension isotherms of the frothers were determined and analyzed with one of the latest adsorption models. The results indicated that the polypropylene glycol frothers showed more surface activity compared to alcohol or other frothers investigated. This is due to the additional reorganization of the PPG molecules on the air/water interface, thus boosting its surface activity.

PHYSICOCHEMICAL PROPERTIES OF QUATERNARY SALTS OF ETHYL ETHER 4-MORPHOLINYL ACETIC ACID

Для четвертичных солей Х-алкил-Х-(этоксикарбонил)-метилморфолиния (алкил: бензил-, додецил-, гексадецил-) получены изотермы поверхностного натяжения на границе водный раствор-воздух, определены значения критической концентрации мицеллообразования, предельной адсорбции, площади молекулы в насыщенном адсорбционном слое. For the quaternary salts of N-alkyl-N-(ethoxycarbonyl)methylmorpholinium (alkyl: benzyl-, dodecyl-, hexadecyl-), surface tension isotherms were obtained at the water-air interface, values of critical micelle concentration, limiting adsorption, and the area of the molecule in saturated adsorption layer were determined.

Interfacial Properties of Tridecyl Dimethyl Phosphine Oxide Adsorbed at the Surface of a Solution Drop in Hexane Saturated Air

The surface tension of C13DMPO aqueous solution drops in hexane vapor is studied using the drop profile method. The hexane was injected into the measuring cell at three different conditions: before the formation of the solution drop, at a certain moment during the adsorption process, and after reaching the equilibrium of surfactant adsorption. The surface tension values for all experiments at the same concentration and different injection situations ultimately coincide with each other after attaining the final equilibration stage. The equilibrium surface tension isotherms of C13DMPO solutions, and the adsorption of both components—surfactant and hexane—were calculated. It was shown that the presence of surfactant leads to an increased hexane adsorption.

Preparation of foaming agents for dust suppression of coal particles

The results of the study of foams stabilized by solid coal particles are given. The method of sedimentation analysis determined the most likely radius of coal particles equal to 20.28 microns. Foaming ability was determined by the height of the foam column obtained by the method of bubbling within 1 min. Foam stability was determined by the time of complete destruction of the foam column. Foams stabilized by the compositions of anionic surfactants – sodium dodecyl sulfate (DDSNa) and sulfonol (SF) with polyvinyl alcohol (PVA) in the presence of hydrophobic solid particles of coal showed greater foaming capacity and stability compared to foams from individual surfactants. The surface tension isotherms of aqueous solutions of surfactants, PVA, and their mixtures were obtained. An increase in the stability of foams in the presence of coal particles corresponds to a decrease in the surface tension at the liquid-gas interface. The stability of foams obtained from surfactant-PVA compositions is explained by the combined influence of thermodynamic (reduction of surface tension) and structural-mechanical (increase in viscosity of inter-membrane fluid) of stability factors. These properties of foams can be used to suppress dust in coal mining.