English English

Vol. 7 Issue 2

Archives Journal Chemical Bulletin Vol. 7 Issue 2

Optimization of the flow part of the microfluidic channel

https://doi.org/10.58224/2619-0575-2024-7-2-4-12
, ,
 4-12 p.
Abstract
In this paper, the features of microfluidic channel optimization are considered. The microfluidic channel is a key component of the microreactor, its shape and features of the hydrodynamic regime directly affect the successful course of chemical reactions carried out in it. The microfluidic industry regulates processes occurring in small volumes of liquids – on the order of a nano liter or less. It is applicable to various fields such as microelectronics, pharmaceuticals, specialty chemicals, etc. The Comsol Multiphysics computational modeling program was used as an optimization tool. It is based on the finite element method, which allows you to accurately model the problems of the hydrodynamic profile. In this article, the simplest form of a microchannel is considered – a 0.75 mm circular channel with a mixing cell. The mathematical modeling of the process is given, the optimality criterion adequate for the task is determined. As one of the components of this criterion, diodicity was used – a criterion that determines the ability to pass a stream in the forward direction, provided there is a reverse flow. As a result of this work, the most optimal shape of the microreactor channel satisfying the required process conditions was identified, the main hydrodynamic parameters were obtained and the dependence of the diode on the criterion used was determined.
PDF

Electrophilic-nucleophilic and hydrophobic properties of surface-modified metals

https://doi.org/10.58224/2619-0575-2024-7-2-13-25
,
 13-25 p.
Abstract
The method of layering different-sized molecules of ammonium and organosilicon compounds on metals, developed at the St. Petersburg Mining University, is a promising method for hydrophobization and stabilization of the surface properties of dispersed metal materials. A comparison was made of the hydrophobicity of samples based on PMS-1 copper powder processed in pairs of modifiers in mixed or sequential modes. To provide a physicochemical substantiation of the mechanism of surface hydrophobization, quantum chemical modeling and assessment of the electrophilic-nucleophilic properties of isolated modifier molecules in the HyperChem software package, as well as their adsorption interaction with a cluster model surface in the Gaussian 09 software package, were carried out. It was established that the adsorption energy values lie in range 64–127 kJ/mol, which corresponds to the chemical interaction of ethylhydride siloxane molecules and quaternary ammonium compounds (QAC) with the metal. It has been established that samples containing modifiers with different electrophilic-nucleophilic properties in the surface layer of the metal are characterized by better hydrophobicity. Also, the key role of QAC in the hydrophobization of the surface has been established by providing a stronger heteroatomic interaction with the metal surface and the formation of a preparatory QAC sublayer for structurally similar functional groups.
PDF

Study of sorption properties of silicon dioxide based on overburden rocks for the extraction of dyes from wastewaters

https://doi.org/10.58224/2619-0575-2024-7-2-26-42
 26-42 p.
Abstract
The article presents the results of a study of the sorption properties of silicon dioxide obtained from overburden rocks for use in the removal of methylene blue, an organic cationic thizian dye, from aqueous solutions. The aim of the study was to evaluate the sorption properties of silica and its efficiency in the removal of methylene blue from aqueous solutions. Experimental data showed that the sorption efficiency depends on temperature, pH and stirring speed. It was found that increasing pH and stirring speed promotes sorption enhancement, while increasing temperature decreases sorption efficiency. In addition, the possibility of regeneration of silica after sorption was investigated and it was shown that its sorption properties are practically unchanged after several cycles of use. The maximum sorption capacity was 515.9 μmol/g. In a previously published paper, under standard conditions, the maximum sorption capacity was 438.22 μmol/g. The results emphasize the potential of silica as an effective and sustainable sorbent for the removal of organic dyes from wastewater. Thus, silica can be recommended for multiple use in wastewater treatment processes due to its high thermal stability and durability.
PDF

Optimization of a typical condensation process using the example of isophorone synthesis in a microchannel

https://doi.org/10.58224/2619-0575-2024-7-2-43-52
, , ,
 43-52 p.
Abstract
The work is devoted to the method of obtaining isophorone in a microchannel. Numerical and experimental optimization of the process of obtaining isophorone in a microchannel has been carried out. Isophorone is an unsaturated cyclic ketone, widely used in industry as a solvent for nitrocellulose paints, as well as as an inter-mediate for the synthesis of other compounds. The synthesis was carried out in microchannels. Microchannels are channels with a diameter of less than 1 mm. Their main feature is the possibility of carrying out various types of reactions requiring high pressures and temperatures. Due to the small internal volume, all processes occurring in them are easily intensified, high accuracy and efficiency of the experiment can be achieved. Parameters such as reaction temperature and reagent consumption varied. A new approach to conducting the experiment was used, based on minimizing the control parameters used and combining them correctly. This approach requires high ac-curacy and reproducibility of the results, so the microchannels used in this work are the best choice for such tasks. A mathematical model of the reaction based on systems of equations of varying complexity has been developed. Three-dimensional and two-dimensional contour diagrams are constructed to visualize the mathematical model of the process. The best technological parameters of the process have been established.
PDF