Construction of a mathematical model of the film absorber for sulfating two-component mixtures of organic substances

The processes that occur in film absorbers during the sulfation of two-component mixtures of organic substances are quite complex and require mathematical modeling. This paper reports the construction of a mathematical model that makes it possible to adequately describe the process of sulfation involving gaseous sulfur trioxide in the production of surfactants. Based on the model, it became possible to investigate this process for higher alcohols of fractions С12–С14 and monoethanolamides of higher fatty acids of coconut oil. The data are given on the comparison of mathematical modeling results based on the mathematical model built with known experimental data and results of alternative mathematical modeling for different ratios of the length of the reaction pipe to its diameter (l/d). It is shown that the error in comparing the experimental data was 4.8–9.6 % at l l/d=29; 1.1–8.7 % at l/d=70; 3.9–12.3 % at l/d=144. The error in comparing known results of alternative mathematical modeling was, respectively, 6.3–7.2 %, 0.1–6.5 %, 0–1.0 %. These results were obtained for the molar ratio in the range of 1.0–1.15 and the SO3 concentration in the stream of 4.0–6.0 %. Such findings suggest that the established dependences of the basic parameters for the sulfation process are adequate in terms of the absorber length and its radial direction. Therefore, the mathematical model built does hold within the considered ranges of input variables. Consequently, it could be used in the theoretical study of the process of sulfation of two-component mixtures of organic substances by gaseous sulfur trioxide in a film absorber with a downward flow of phases. The results obtained could be used in practice, in particular in the manufacture of high-quality products for the cosmetic industry.

RESEARCH OF THERMAL AND MASS-EXCHANGE PROCESSES IN GAS-LIQUID FILM ABSORBERS IN SURFACE-ACTIVE TECHNOLOGY

The article states that surfactants have an asymmetrically constructed molecule that contains hydrophilic and hydrophobic groups. The main department of surfactant production is the process of sulfation of organic matter with gaseous sulfur trioxide. It is shown that the process of sulfation in gas-liquid film absorbers consists of the following stages: the process of mass transfer of sulfur trioxide from the gas stream to the liquid phase; the process of absorption of sulfur trioxide by organic matter with the passage of an exothermic chemical reaction; the process of heat exchange between the liquid phase and the gas stream; the process of heat exchange between the liquid phase and the flow of cooling water. Studies of heat and mass transfer processes at these stages make it possible to select the necessary equations for the calculation of heat transfer coefficients, heat transfer coefficients and mass transfer coefficient. It is recommended to calculate the heat transfer coefficient from liquid to gas by the equation when the diffusion and thermal Prandtl numbers are close to unity. The use of the classical equation to calculate the heat transfer coefficient from the liquid phase to the wall of the reaction tube did not give the desired result. Therefore, an equation was used that takes into account the properties of the gas-liquid flow as a whole. It is recommended to calculate the heat transfer coefficient from the reaction pipe wall to the cooling water flow according to the classical Nusselt equation. Experimental data processing data for calculating the density and dynamic viscosity of the reaction mass along the length of the reactor are presented. The equation for calculating the mass transfer coefficient was obtained by analyzing 6 equations of different authors who were engaged in the process of sulfation of organic substances. A mathematical description of the sulfation process in a film absorber was developed for analysis. During the development of the mathematical description, the balance equations of mass and heat transfer for the reaction tube were compiled. Based on the results of mathematical modeling, an equation was chosen that includes the tangential stress at the gas-liquid interface. The results of mathematical modeling were compared with Gutierrez's experimental data and the results of Dabir's mathematical modeling. The obtained results will be used in mathematical modeling of the sulfation process in a film absorber.

Photonic Crystal Fiber Sensor for the Detection of Different Hazardous Gases

Three different Photonic Crystal Fiber (PCF) gas sensors are designed to detect five different gases for a wide range of wavelengths. The three unique configurations are designed based on four outer Elliptical cores PCF (4E-PCF), four outer Circular cores (4C-PCF) PCF, and different Eight Elliptical cores PCF (8E-PCF) to analyze and sense the light interface with applied gases. For three proposed gas sensors, the sensing parameters for five different hazardous gases, such as relative sensitivity, effective area, birefringence and dispersion, are acquired. The five different gases considered for the sensor investigation are Sulfur trioxide [SO3] (20oC), Tetracholorosilane [SiCl4], Tetracholoromethane [CCl4], Turpentine [C10H16], Tin Terra chloride [SnCl4]. Among the three designs, 8E-PCF yields a maximum sensitivity of 75.75%, an effective area of 2.45µm2, and a birefringence of 0.0421 for SnCl4 gas.

Experimental Investigation of Ammonia and Sulfur Deposition Characteristics in Rotary Air Preheater

With the application of selective catalytic reduction (SCR) technology, the operation of rotary air preheaters is faced with a challenge, the fouling problem caused by ammonium bisulfate (ABS). In previous studies, within the operational temperature range of the preheater, the gaseous ammonia and sulfur trioxide (or H2SO4) in the flue gas can react to form ABS and ammonium sulfate (AS). The initial condensation temperature of ABS might be over predicted due to the effect of the formation of AS, which has a higher initial formation temperature than ABS. In this study, the effects of the deposition temperature, ammonia-sulfur molar ratio and molar product of inlet flue gas on the deposition characteristics of inducing ash deposition compounds were experimentally studied to provide guidance to prevent fouling and corrosion of rotary air preheaters. The results show that the main path to generate ABS is the reaction between H2SO4 and NH3. With the increase in the deposition temperature, the contents of NH4+ and SO42− in the sediments decrease continuously, and the proportion of AS deposition increases. On the contrary, with temperature decreasing, more ABS is deposited. When the molar ratio of ammo-sulfur in the inlet flue gas increases, the proportion of AS in the sediments increases, and the deposition rate also gradually increases. When the ammo-sulfur product in the inlet flue gas increases, the concentrations of both NH4+ and SO42− in the sediments increased in a nearly consistent trend. The variations of the ratio and deposition rates of the two ions in the sediments were not obvious. The ratio of NH4+ and SO42− remains at about 1.2, and the sediment is mainly ABS.

Chemical Hemisynthesis of Sulfated Cyanidin-3-O-Glucoside and Cyanidin Metabolites

The metabolism of anthocyanins in humans is still not fully understood, which is partly due to the lack of reference compounds. It is known that sulfation is one way of the complex phase II biotransformation mechanism. Therefore, cyanidin-3-O-glucoside and the cyanidin aglycone were chemically converted to their sulfates by reaction with sulfur trioxide-N-triethylamine complex in dimethylformamide. The reaction products were characterized by UHPLC coupled to linear ion trap and IMS-QTOF mass spectrometry. Based on MS data, retention times, and UV-Vis spectra, the compounds could tentatively be assigned to A-, C-, or B-ring sulfates. Analysis of urine samples from two volunteers after ingestion of commercial blackberry nectar demonstrated the presence of two sulfated derivatives of the cyanidin aglycone and one sulfated derivative of the cyanidin-3-O-glucoside. It was found that both the A ring and the B ring are sulfated by human enzymes. This study marks an important step toward a better understanding of anthocyanin metabolism.