Chromatographical Analysis of Meldonium with Preliminary Concentration by Solid-Phase Extraction on Magnetite Nanoparticles

A comprehensive method for meldonium analysis, based on a combination of magnetic solid-phase concentration of the analyte on magnetite nanoparticles modified with cetylammonium bromide (CTAB) cations and its subsequent analysis by thin-layer chromatography (TLC) were developed in the process of study. The influence of a number of factors on meldonium sorption was studied, namely: pH, sorbent mass, sorption and mixing times; optimal extraction conditions were determined. It was found that quantitative sorption proceeded in 20 min with a meldonium extraction degree of 88%. Ethanol was found to be an eluent to desorb the analyte by 95%. The calibration dependences plotted with and without concentration of meldonium were compared. It was established that the use of concentration on two mg of CTAB-modified nanomagnetite reduces the lower limit of the analyzed contents of meldonium in 25 ml of solution by 5 times.

Study on the length of pipe inlet section of pulp fluid based on CFD

In the paper industry, to determine the installation positions of concentration sensor and flow sensor of pulp pipe transportation system, the length of pipe inlet section of pulp fluid must be determined. In order to solve the problem that it is difficult to determine the length of pipe inlet section of pulp fluid, the paper presents a method to determine the length of pipe inlet section of pulp fluid, and the relationship between the length of inlet section and pulp fluid parameters is studied by this method. Firstly, CFD (Computational Fluid Dynamics) method is applied to obtain flow velocity and solid phase concentration distribution data of pulp fluid at different axial positions in the pipe. Then, Pearson correlation coefficient method is applied to analyze these data. Finally, the length of pipe inlet section of pulp fluid is determined according to the obtained correlation coefficient, and the relationship between the length of pipe inlet section of pulp fluid and initial average flow velocity and solid phase concentration is obtained. The conclusion shows that the method can well obtain the length of pipe inlet section of pulp fluid, which provide some theoretical basis for the design of pulp pipe transportation system.

Solid-phase concentration of calcium ions with mineral sorbents in creation of anti-icing materials

The results of an experimental study of calcium ion adsorption processes carried out on various mineral sorbents of natural origin are presented. The sorption properties of the selected objects were studied and the possibility of their use as combined anti-icing materials was evaluated. In the work were investigated technological indicators of the quality of sorbents - the pH of the zero-charge point, the sorption capacity of sorbents and the optimum pH interval to determine the sorption activity of mineral raw materials on calcium ion. Analysis of the adsorption isotherms of calcium ions by the mineral sorbents studied makes it possible to note that the adsorption equilibrium on the clay is established more rapidly than on the opal of the marl type and marl. At the same time, the maximum absorption capacity of clay and marl has close values, which is related to the structure of the sorbent surface and the mineral composition of the materials. Opal of the marl type has a more developed surface, which is illustrated by a much higher absorption capacity and is confirmed by the values of the specific surface area. The obtained experimental data were processed using Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich models. When describing the adsorption equilibrium of calcium ions on mineral sorbents, the Freyndlich isotherm is a more rigorous model, which indicates the presence of a large number of active centers and their exponential distribution on the surface of sorbents. The quantitative characteristics of the adsorption capacity of sorbents, found by adsorption models, made it possible to identify the optimum conditions of processes, establish a relationship between the values of the sorption of calcium ions by their structure and the porosity of the materials. It has been established that opal of marl type is the most effective carrier for producing anti-icing materials. For citation: Dzhigola L.A., Syutova E.A. Solid-phase concentration of calcium ions with mineral sorbents in creation of anti-icing materials. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 98-104