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The development of physicochemical methods for the analysis of objects of complex composition requires the application of methods of mathematical experiment design. This article investigates the possibility of using probabilistic-deterministic design of experiment (PDDoE) for obtaining a mathematical model of the chromatographic separation process of coal tar hydrogenation products on an Agilent 7890A device with an Rxi-5ms column. It is shown that the relationship between the column heating rate and the carrier gas pressure with the values averaged for the entire chromatogram can be established with a high accuracy. It is noted that the accuracy of modeling the individual characteristics of the mixture components’ peaks is less, but remains sufficient for many practical needs. Nonlinear multiple correlation coefficients (NMC) for the dependence of the average retention time and average intensity on the considered factors are more than 0.99; they are more than 0.98 for the average peak width. NMC for the dependence of the resolution with the relation to the peaks of naphthalene and 2-ethylphenol is more than 0.8 at a significant level that sufficient for practice. The quality of the mathematical model was checked by triple registration of the chromatogram at the values of the column heating rate and carrier gas pressure that were not used in the training experiment. The measurement results are excellent squared with those calculated using the obtained generalized equations. The PDDoE method can be recommended as a method for mathematical design of an optimization experiment in gas chromatography.

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Selective extraction of magnesium from asbestos-containing raw materials In this work, great attention was paid to identifying the reasons for the absence of practically implemented technologies for processing chrysotile asbestos wastes and searching for new methods for treating wastes with the aim of obtaining magnesium and other useful products of commercial interest. A series of experiments with solutions of ammonium chloride of different concentrations was carried out to study the kinetics of magnesium leaching. The concentration of magnesium leached increases with the concentration of the NH 4 Cl solution (C Mg = 0.092M; C Mg = 0.1M; C Mg = 0.102M), as well as with the time of the process itself. It was shown that the difference between the leaching rates of magnesium by 3M and 5M NH 4 Cl solutions was not significant, and it was rather large for 1M and 3M solutions. The study of the thermodynamics of magnesium leaching was carried out with 3 molar solution of ammonium chloride at various temperatures. Graphs of the concentration of leached magnesium versus the leaching time at different temperatures of the ammonium chloride solution were plotted based on the results obtained. Experiments showed that the degree of magnesium leaching from asbestos increased with increasing temperature. The activation energy was calculated, which was equal to 44 kJ. Sediment identification was carried out using a laser-atomic emission spectrometer apparatus. The results of the experiment showed that a certain amount of magnesium, calcium and a small amount of other metals were contained in the obtained precipitates. Admixture of calcium does not affect the properties of the precipitate obtained. Leaching tests carried out with the help of ammonium chloride solution of various concentrations showed that the fibrous structure of asbestos was not destroyed.