Abstraсt: Lactic acid is used in a wide variety of application areas, and it is the raw material for the largest-capacity commercial biodegradable plastic – polylactide (polylactic acid (PLA)). The currently licensed technologies for the PLA production have a number of disadvantages: all of them use low-productivity batch fermentation, a large proportion of growth factors in the prime cost of lactic acid, a “gypsum” technology of the lactic acid separation, which produces calcium sulfate waste of about 1 ton per 1 ton of lactic acid. Whereas licensors do not disclose data on the optical purity of the produced lactic acid, although this parameter critically affects the properties of the manufactured polylactide. This article describes the basic biotechnological and chemical-technological solutions for the developed domestic innovative technology for the lactic acid production. A comparison of the achieved characteristics with modern industrial technologies is given. It is shown that the developed technology ensures the production of high optical purity L-lactic acid (not less than 99.4%).
Keywords: high optical purity L-lactic acid, L-lactide, polylactide, polylactic acid, membrane bioreactor, butyl lactate, gypsum-free technology.
Abstraсt: D.I. Mendeleev University of Chemical Technology of Russia has a rich 120-year history. The names of many outstanding scientists are inseparably linked with the university. A.S. Bakaev, N.N. Vorozhtsov, N.M. Zhavoronkov, B.P. Zhukov, A.G. Kasatkin, S.V. Kaftanov, V.A. Koptyug, V.V. Korshak, V.A. Legasov, G.S. Petrov, A.N. Planovskiy, V.N. Yung, N.F. Yushkevich, G.A. Yagodin and many others are the pride of Soviet and Russian science. We dedicate this article to the famous «mendeleevets» Viktor Vyacheslavovich Kafarov, Academician of the USSR Academy of Sciences, founder of the school of cybernetics in chemical technology. With this publication we begin a series of articles about the famous scientists from Mendeleev University.
Keywords: D.L. Mendeleev University of Chemical Technology of Russia, cybernetics of chemical-technological processes, scientific school of academician Kafarov.
Abstraсt: New contact devices are presented for creating installations for detritiation of low-level water flows in the framework of solving an important problem in the field of radioactive waste management. The results of an experimental study of the process of isotopic exchange between hydrogen and water in membrane-type contact devices of various designs with a Nafion-type membrane and a heterogeneous platinized catalyst are presented. It is shown that contact devices with tubular membranes make it possible to carry out the process at a linear velocity of the vapor-gas flow of more than 1 m/s, while an increase in the flow velocity by 5 times leads to an increase in the mass transfer coefficient by more than 2 times. The average value of the observed activation energy, calculated in the temperature range of 323-358 K, for all investigated contact devices was Eactobs = 32±4 kJ/mol, which indicates a significant contribution of diffusion processes to the resistance to mass transfer. The proposed contact devices can be used to create compact high-performance separation plants for solving the problems of detritiation of large volumes of tritium-containing aqueous waste.
Keywords: detritiation, aqueous radioactive waste, chemical isotope exchange, water-hydrogen system, membrane contact device, nation membrane, heterogeneous catalysts, mass transfer coefficients.
Abstraсt: In the processes of gas dedusting, where there is a possibility of sticking in the holes, sieve trays without weirflows are used. Comparative studies of hydrodynamic of operation of counterflow (weeping) sieve trays with fixed valves and round holes. The volume fraction of liquid on the tray does not depend on the design of the tray and the liquid flow rate, and well described by the Bennet correlation. For sieve trays with fixed valves, a local minimum of entrainment is in the zone of gas velocities from 1 to 2.5 m/s; in the same zone, a stable height of clear liquid is observed. Sieve trays with fixed valves have the following advantages: a stable height of a clean liquid when liquid and gas loads change, less entrainment, stable operation at lower liquid flow rate. Renovation gaz absorbers with counterflow sieve trays, the use of trays with fixed valves allows to reduce energy consumption for the circulation of liquid and gas pressure losses
Keywords: sieve tray, fixed valve, counterflow tray, entrainment, dedusting of gas.
Abstraсt: The analysis of the market demand for aromatic hydrocarbons was realized. Based on the analysis of the publications of simulation the the processes of aromatization of alkanes, the chemical reactions scheme and the technological line of the process of aromatization of gas condensate was selected as object of the simulation. The publications devoted to the use of simulators for create of computer models of chemical production are analyzed. The computer model of the technological line of the process of aromatization of the gas condensate was realized by using the simulator CHEMCAD. The study of the aromatization chemical reactor was realized by using the computer model. It is proposed to simulate the process of aromatization in the reactor by using model components in order to further include the model in the model of the technological scheme. The calculations of the constructive parameters of heat exchangers and separators of the technological line of the production of aromatic hydrocarbons from gas condensate was realized. Initial data for the development of the project of this chemical production was prepared.
Keywords: model, toluene, aromatization, simulator, module, production.
Abstraсt: The widespread practical use of N-methylpyrrolidone (MP) and the lack of reliable data on its physicochemical properties necessitate the experimental study of this solvent and the development of methods for approximate calculation of the properties of solutions in MP. The paper presents the results of a study of the heat capacity and density of solutions of inorganic compounds in MP and its mixtures with water. Experimental data are presented in the form of polynomial equations convenient for practical use. Standard partial molar heat capacities and volumes of nonelectrolytes, electrolytes and ions in MP solutions and MP-water mixtures are calculated. The dependences of the studied heat capacity, density and partial molar values on various parameters are established and methods of approximate calculation of these properties are proposed on this basis.
Keywords: N-methylpyrrolidone, solutions, heat capacity, density, calculation methods.
Abstraсt: In the era of rapid technological development, higher requirements are imposed on modern materials. The production of a finished product whose technology corresponds to the concept of “best available techniques” is not insignificant. For materials obtained by high-temperature sintering, there is a demand for lower curing temperatures to obtain a finished sample with the same physical and operational characteristics, to save energy and resources. Ceramics doped with various additives can serve as the main material that can be used in the field of creation of structural materials. Advanced multilayer carbon nanotubes with high strength characteristics are considered as additives. The paper considers the influence of the concentration content of eutectic additives as well as the firing regime on the strength characteristics of the structural ceramic material doped with carbon nanostructures. The results were obtained by IR spectroscopy and X-ray phase analysis. To evaluate the physical and operational properties, the bending strength (by three-point method) was determined, and the open porosity obtained by hydrostatic weighing was calculated. In the course of the work, it was found that the best mechanical properties have the samples with two-component and four-component additives, and the optimal concentration of carbon nanotubes for the four-component additive was shown. Such material can be applied in military developments the creation of a new generation of ceramic armor. Further research will focus on a detailed study of the effects of eutectic additives.
Keywords: structural ceramics, sintering, carbon nanotubes, zirconium dioxide, aluminum oxide, functionalization, modification.
