Concentrated Hydrochloric Acid Research Articles

Гидролиз целлюлозы с использованием газовоздушных смесей хлористого водорода

Abstract. Microcrystalline cellulose (MCC) is a common product used in pharmaceutical, food and other industries. MCC is obtained by liquid-phase hydrolysis of cotton or wood bleached pulp with diluted 0.5–10.0 % mineral acids at a temperature of 100–140 °C. This process requires significant consumption of acid, water, and heat energy. Production of MCC in general is very expensive, which determines its high cost and the need to find alternative methods of cellulose hydrolysis. It is proposed to hydrolyze cellulose with concentrated hydrochloric acid produced by absorption of hydrogen chloride. We studied the processes of hydrogen chloride adsorption by bleached wood pulp with 8–18 % humidity. It is shown that adsorption of hydrogen chloride is determined by pulp humidity and is 3–5 % of the dry pulp mass. The sorption of hydrogen chloride leads to the formation of hydrochloric acid with a concentration of 25–40 % in the raw material moisture, significant heating of the mass and rapid hydrolysis of the amorphous cellulose fraction. It has been found that the use of pure hydrogen chloride for saturation causes strong darkening and humification of pulp. We recommend the use of hydrogen chloride gas-air mixtures to saturate the pulp, which will significantly reduce the sorption temperature and eliminate the strong darkening of the pulp during hydrolysis. The adsorption of hydrogen chloride by cellulose proceeds at an extremely high rate and is accompanied by the formation of a clearly visible sorption front at a temperature of 45–60 °C. Hydrolysis occurs for 15–30 min at 40–60 °C until the amorphous cellulose fraction is completely decomposed. A very small amount of monosaccharides is formed (4 % of dry pulp). The yield of MCC is high, more than 95 %. These circumstances are probably related to the recrystallization of a part of the amorphous fragments of cellulose macromolecules, which is a characteristic of hydrolysis with concentrated acids. The product obtained by cellulose hydrolysis is identical to MCC according to the data of IR spectroscopy, X-ray diffraction and viscometry. The article shows the high efficiency of cellulose hydrolysis with hydrogen chloride gas-air mixtures compared to traditional methods of MCC production.

EVALUATION OF GROUND SERPENTINE ROCK AND GROUND MAGNESIUM LIMESTONE AS MAGNESIUM SOURCES FOR OIL PALM NURSERY SEEDLINGS

Treatment of ground magnesium limestone and ground serpentine by boiling in 5 ml of concentrated nitric (HNO3) acid and 10 ml of concentrated hydrochloric (HCl) acid for 1, 2, 4, 8 and 16 hours in the laboratory showed mean magnesium oxide (MgO) content of 18.2 and 29.20 per cent, respectively. The experiment for the two sources of magnesium (Mg) was carried out on oil palm nursery seedlings grown in large polybags with coarse river sand as the medium of growth. The rates were 5, 10, 20 and 30 g of MgO, applied in planting holes at the time of transplanting of three-month-old pre-nursery seedlings. Initially, up to four months, the leaf 3 Mg levels were slightly higher in ground serpentine treatment, although the difference in values was statistically not significant when compared to the rest of the treatments. As the age of the seedlings increased, there was a continuous decline in leaf Mg levels for all treatments. At the eighth month, the Mg levels of oil palm leaves grown with ground magnesium limestone were significantly higher than the control treatment with no Mg. The source of Mg had no influence on the vegetative growth of seedlings, as all the treatments including control showed no significant differences for the measured growth parameters. In conclusion, ground serpentinite rock is comparable to ground magnesium limestone as a source of Mg. The rate of 30 g MgO per plant, when placed in the planting hole, is insufficient to meet the oil palm needs after the fourth month of application. Higher rates or different methods of application may be needed and to be studied in subsequent trials.

Synthesis of Patchouli Esters from Patchouli Oil in the Presence of Homogeneous and Heterogeneous Catalyst

Patchouli alcohol was isolated from patchouli oil by fractional distillation under reduced pressure. Patchouli esters were then prepared from isolated patchouli alcohol via esterification reaction in the presence of homogeneous (concentrated hydrochloric acid) and heterogeneous (acid-activated bentonite) catalysts. Fractional distillation under reduced pressure was carried out by heating patchouli oil under a pressure until 0 mmHg. Esterification reaction was carried out by heating patchouli alcohol with propionic acid in the presence of an acid catalyst at 100-110 for 3 h The products were characterized using FTIR and GCMS spectrometers. The esterification reaction with HCl 37% and bentonite catalysts produced patchouli propionate in 26% and 21% yields, respectively.

Ultrafast Degradation and High Adsorption Capability of a Sulfur Mustard Simulant under Ambient Conditions Using Granular UiO-66-NH2 Metal-Organic Gels.

Zirconium-based metal-organic frameworks (Zr-MOFs) have been considered as prospective materials for the degradation of nerve chemical warfare agents (CWAs) but show poor catalytic performance toward blister agents. Moreover, the powder issues and the poor adsorption capability also remain as the major challenges for the application of Zr-MOFs in practical CWA detoxification. Herein, a series of defected granular UiO-66-NH2 metal-organic gels are synthesized via adjusting the amount of added concentrated hydrochloric acid for the decontamination of 2-chloroethyl ethyl sulfide (2-CEES), a sulfur mustard simulant. The half-life of 2-CEES decontaminated by defected granular UiO-66-NH2 metal-organic gels can be shortened to 7.6 min, which is the highest reported value for MOFs under ambient conditions. The mechanism of decontamination is that the amino group on the linkers in UiO-66-NH2 MOGs undergoes a substitution reaction with 2-CEES to yield 2-(2-(ethylthio)ethylamino)terephthalic acid, which is less toxic and fixed in the frameworks. The recycling test corroborates that the granular UiO-66-NH2 xerogels possess good stability and reusability. Static adsorption and desorption tests show that UiO-66-NH2 xerogels possess a high 2-CEES vapor adsorption capacity of 802 mg/g after exposure for 1 d and only 28 wt % desorption capacity after air exposure for 7 d. The dual function of ultrafast degradation and high adsorption capability provide a firm foundation for using UiO-66-NH2 xerogels as a future protection media.

Kinetic Analysis of Aluminum Extraction from Ethiopian Kaolinite Using Hydrochloric Acid

The aim of this study was kinetic investigations of aluminum extraction from Ethiopian kaolinite with hydrochloric acid. The effects of extraction parameters, namely, solid-to-liquid ratio (0.05, 0.075, 0.100, and 0.125 g·mL−1), acid concentrations (2, 3, 4, and 5 M), reaction temperature (50, 60, 70, and 80°C), and time (20, 40, 60, 80, 100, 120, 140, 160, and 180 min), on yield of aluminum were investigated. The results revealed that the extraction yield of aluminum increased with increase of acid concentration, reaction temperature, and time and declined with increase of solid-to-liquid ratio. The kinetic analysis of aluminum extraction was evaluated using pseudohomogeneous, nucleation growth (Avrami), and shrinking core models. The results showed that kinetics of aluminum extraction were controlled by surface chemical reaction. The experimental results were well fitted by the shrinking core model of surface chemical reaction with first-order rate. The activation energy and the preexponential factor were 25.40 kJ·mol−1 and 0.949 cm·min−1, respectively. The leached solution samples were crystallized using evaporation and concentrated hydrochloric acid pouring. The volume ratios of concentrated hydrochloric acid to the samples were from 0.30 to 0.90 (v/v). The crystallization efficiency of aluminum chloride hexahydrate crystals increased with volume of hydrochloric acid and crystallization time. The crystallization yield of aluminum chloride hexahydrate crystals reached 90%. This study’s results clearly revealed that Ethiopian kaolinite could be a promising raw material to produce aluminum chloride hexahydrate, which could be used for water treatment application.

Sono-synthesis of cellulose-TiO2 nanocomposite adsorbent for fast cleaning of anionic dyes containing wastewater

This work was devoted to synthesizing a composite of cellulose-TiO2 by the in-situ process using the sol-gel method and applied on representatives of acid dyes to determine the functionality regarding the adsorption of dyes from aqueous solution. The composite particle adsorbed 100% dyes within 3 min of the direct application. XRD, FTIR, SEM, and Zeta potential tests were conducted to investigate the effect of crystal, molecular structure, surface morphology, and surface charges on the absorption speed of cellulose-TiO2 composite particles. The experimental results revealed that the cellulose was partially hydrolyzed by concentrated hydrochloric acid and left some positive charge on the surface of cellulose during the synthesis of the composite structure. The test results demonstrated that nano TiO2 with a thin layer of cellulose covered the surface of undegraded cellulose particles. The structural changes in the composite made them beneficial to fast dye adsorption. The effect of initial dye concentration, composite dosage, and temperatures were also investigated to find the optimum condition for dye adsorption. The optimum condition was found at the initial concentration of 400 mg/l, dosage of 0.10 g, and temperature of 25 °C. The removal efficiency and maximum adsorption capacity at this condition were 100% and 40 mg/g, respectively. The adsorption data suggested that the data was well fitted with a pseudo-second-order model for adsorption kinetics and Langmuir model for adsorption isotherm. Thermodynamic analysis revealed that the adsorption process was physisorption, spontaneous, random, and endothermic. Overall, in this work, the developed cellulose-TiO2 nanocomposite might be an economical and efficient adsorbent to remove dyes from wastewater.

Revealing the Anticorrelation Behavior Mechanism between the Grotthuss and Vehicular Diffusions for Proton Transport in Concentrated Acid Solutions.

In this study, we performed reactive molecular dynamics simulations to characterize proton solvation and transport in concentrated hydrochloric acid solutions. The correlation contribution to the total proton mean square displacement is found to be negative for all acid concentrations, indicating the anticorrelation between the Grotthuss and vehicular diffusions. For the vehicular diffusion, the hydronium ions tend to move freely toward the lone pair side independent of acid concentrations, whereas for the Grotthuss diffusion, the proton hopping direction is limited to one of the hydrogen-bonded water molecules on the opposite side of the lone pair region, which are specifically oriented with respect to the neighboring hydronium ion at higher acid concentrations. This result is justified by our findings of the higher fraction of proton rattling with the single hopping event and longer hydrogen bond lifetimes at higher acid concentrations. However, the angular distribution for both the vehicular and Grotthuss diffusions is found to be rather broad and comparable for all acid concentrations, and thus, the anticorrelation shows a minimal dependence on the acid concentration. Our results reveal that the anticorrelation behavior between the vehicle and Grotthuss diffusions is attributed to the amphiphilic nature of hydronium ions and thus is independent of the acid concentrations in solutions.

THE METHOD OF CHEMICAL FERMENTATION IN ARTIFICIAL GASTROINTESTINAL JUICE OF ECHINOCOCCUS MULTILOCULARIS LARVOCYST AS A METHOD FOR OBTAINING A URIFIED VIABLE PROTOSCOLEX CULTURE

For the first time in the world, a pure viable culture of E. multilocularis protoscolexes was isolated by digesting the parasite's larvocysts in artificial gastric juice. The article describes a unique biological, biochemical method for obtaining a culture of E. multilocularis protoscolexes purified from the connective and other tissues of the parasite larvocysts, including dead/immature protoscolexes during isolation. Methods based on the digestion of tissues in artificial gastric juice (IGF) have proven themselves well, especially in the laboratory diagnosis of trichinosis. Mixed with IGS at the rate of 1:10 (1 g of larvocyst fragments per 15 ml of solution) of the following composition: tap water – 1000 cm3 (temperature 41–42 oC); concentrated hydrochloric acid (specific gravity 1.2) – 10 cm3; food pepsin – 6.0 g; NaCl – 9.0 g. The developed method guarantees the production of viable protoscolexes of the parasite. The viability of the isolated protoscolexes was assessed by sediment microscopy with a 4×10 lens magnification for their integrity, locomotor activity, and the presence/absence of foreign matter. The method is simple to perform, does not require additional equipment and high material costs, allows you to increase the yield of pure viable E. multilocularis protoscolexes up to 95–98%.

Thermo-kinetic modelling of the acidic leaching of anorthosite: Key learnings toward the conception of a sustainable industrial process

• Specific ion Interaction Theory model can suitably describe the electrolyte solution. • Geochemical simulation gives conditions for Al 3+ extraction & SiO 2 (am) precipitation. • Gudvangen anorthosite dissolution proves to proceed in chemical reaction regime. • Kinetic model helps refining process parameters (incl. particle size distribution). • The counter-current configuration can outperform the batch performance. The world is facing critical technological and environmental challenges in the production of basic materials in high demand, such as aluminium and silica, whose processes were developed long ago. New production routes, involving using alternative resources and innovative technological solutions, are needed to secure access to these base materials at a lower cost to the environment, in terms of waste and carbon footprint. The European project AlSiCal is currently investigatingan environmentally friendly multi-step process for producing alumina and silica from anorthosite, an abundant feldspar mineral. The present paper focuses on the modelling strategy of the dissolution of anorthosite in concentrated hydrochloric acid, which is the first step of the AlSiCal process. The objectives of this study are (i) to give a reliable first-level prediction of the product speciation in the aqueous and solid phases, (ii) to provide the sensitivity of the process to key operating variables, and finally, (iii) to evaluate the performance of both batch and continuous leaching processes. The proposed methodology is based on the coupling of geochemical equilibrium simulations and particle reaction models, using different computational tools and relevant literature data. This makes it possible to select the favourable operation window and process configuration for the quantitative extraction of aluminium in solution and the production of amorphous silica with an acceptable purity for large-market applications.

Hyper‐Raman study of hydrated excess protons in water: Measurement of concentrated HCl solution

AbstractWe report hyper‐Raman (HR) spectra of concentrated hydrochloric acid solutions for the first time. HR signals from the OH stretching region to the low‐frequency region reflect the presence of chloride anions solvated in water. By contrast, it turns out that HR spectroscopy is insensitive to the presence of excess protons in water. HR spectra of HCl solutions do not show any signature of a proton continuum and shoulders on the high/low‐frequency sides of the bending mode of H2O in stark contrast to IR spectroscopy. Moreover, we found that a sharp HR signal around 500 cm−1 appear in 532 nm excited HR spectra. A laser power dependence indicates that this signal comes from a photochemical reaction. The absence of this signal under 1064 nm HR excitation and 532 nm Raman excitation suggests that the resonance (hyper‐)Raman effect enhances the signal from the photoproduct.

Synthesis and characterization of nano-SiO2@octadecylbisimidazoline quaternary ammonium salt used as acidizing corrosion inhibitor

AbstractAiming at the current situation that the existing acidizing corrosion inhibitors are difficult to apply in high temperature, high concentration acid, and other complex conditions, this article uses nano-SiO2as the core and preferably functional monomers to synthesize nano-SiO2@octadecylbisimidazoline quaternary ammonium salt (nano-SiO2@OBQA). Analytical methods such as nuclear magnetic resonance, infrared, and scanning electron microscopy were used for characterization. The corrosion inhibition performance of the N80 steel sheet by nano-SiO2@OBQA in 20% concentrated hydrochloric acid was studied using the high-temperature corrosion testing machine and adsorption isotherm model combined with quantum chemistry calculations to explore its mechanism of action. The results show that nano-SiO2@OBQA has good high-temperature resistance. When the temperature is 180℃ and the dosage of nano-SiO2@OBQA is 4%, the corrosion inhibition rate is 61.42 g·m−2·h−1. Studies have shown that the adsorption of nano-SiO2@OBQA on the surface of the N80 steel sheet follows the Langmuir isotherm adsorption model, which is spontaneous chemical adsorption.

Separation of Pd(II) and Pt(IV) in concentrated hydrochloric acid using thin-layer oil membrane and comparison with conventional extraction

This study proposes a new thin-layer oil membrane (TOM) extraction strategy for enhanced mutual separation of Pd(II) and Pt(IV) chlorocomplex anions in concentrated aqueous hydrochloric acid solutions using di-n-butyl sulfoxide (DBSO) as an extractant. It was discovered that Pd(II) could be preferentially extracted even in concentrated hydrochloric acid solutions. The separation coefficient between Pd(II) and Pt(IV) considerably increased than that between them during conventional extraction using a separating funnel. A new extractor was designed to perform TOM extraction by spreading a thin layer of organic extractant liquid membrane on the surface of aqueous feed solutions under laminar flow. A simplified TOM extraction model and controlled experiments were used to investigate the effect of H+ and Cl− ion concentrations on the mutual separation between Pd(II) and Pt(IV). Molecular dynamics (MD) simulations were used to understand the microscopic separation mechanisms at the molecular level. Experimental results revealed that the competitive distribution of H+ and Cl− ions in the boundary layer along the normal vertical direction of the organic-aqueous interface are crucial in enhancing the separation between Pd(II) and Pt(IV). The competitive adsorption and enrichment of Cl− ions at the interface prevent DBSO molecules from being protonated by H+ ions, which is beneficial for the substituted coordination of DBSO molecules with PdCl42−. However, the ionic association of protonated DBSO molecules with PtCl62− remains dominant at the interface. As a result, even in concentrated hydrochloric acid solutions, the difference in mass transfer between PdCl42− and PtCl62− toward the interface was intensified.

Development and validation of a novel evaporation setup-assisted TLC method with fluorescence detection for determination of flibanserin in pharmaceutical and biological samples

A specific and sensitive thin layer chromatographic method coupled with fluorescence detection for determination of flibanserin (FLN) that treats woman hypoactive sexual desire disorder was developed. The proposed method depends on the enhancement of FLN native fluorescence intensity via the exposure of the developed TLC plate to concentrated hydrochloric acid vapors. Herein, an evaporation setup needed for HCl vapors exposure step was designed for the first time to ensure a uniform distribution of the vapors throughout the developed bands on the plate. Chloroform: methanol (9.5: 0.5, v/v) was the optimum mobile phase that gave a compact band (Rf= 0.44 ± 0.02) using TLC aluminium plates precoated with silica gel G 60F254 as a stationary phase. After exposure of the developed TLC plate to HCl vapors, the FLN bands emission intensities were measured after excitation at 275 nm. Conferring ICH guidelines, the linearity range was 20.0 – 1500.0 ng/band with a good linear relationship (r= 0.9998). Detection and quantitation limits were 5.12 and 15.50 ng/band, respectively. Also, the method was validated for accuracy, precision, robustness, specificity and selectivity. Statistical analysis verified the suitability of the proposed method for estimation of FLN in tablets and in human plasma with acceptable recoveries (98.07–101.45%).

Removal of Gaseous Hydrogen Sulfide by a FeOCl/H2O2 Wet Oxidation System

The removal of gaseous hydrogen sulfide using FeOCl/H2O2 was studied. The effects of the FeOCl dosage, the H2O2 concentration, the reaction temperature, and the gas flow rate on the removal of H2S were investigated. The reaction products were analyzed, and the characterization of FeOCl was carried out by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and electron paramagnetic resonance spectroscopy. Furthermore, radical quenching experiments were carried out using butylated hydroxytoluene, isopropanol, and benzoquinone. It was found that the H2S removal rate for a H2S gas concentration of 160 ppm reached 85.6% when bubbling through 100 mL of an aqueous solution containing FeOCl (1 g/L) and H2O2 (0.33 mol/L) at 293 K with a flow rate of 135 mL/min. Although the dissolution of chlorine in FeOCl was found to result in reduced catalytic performance, the activity was restored after soaking the catalyst in concentrated hydrochloric acid (37%) and subsequent calcination. The mechanism of H2S removal was also discussed, and it was found that this process was controlled by H2S diffusion. FeOCl was found to activate H2O2 and produce radicals, such as •OH and •O2–, resulting in the formation of a water film rich in radicals on the FeOCl surface. Following the diffusion of H2S into the water film, it underwent oxidation by radicals to produce SO42–. Overall, the catalyst and the product can be effectively separated.

DFT Analysis of the Formation of a Titanium n-Butoxide Derivative [[Ti[O(CH2)3CH3]2Cl·OH]2]2 through OH Bridge Formation and Molecular Interactions between Butoxy Groups

Abstract The structural changes of titanium n-butoxide derivatives in coatings prepared from a mixture of titanium butoxide in concentrated hydrochloric acid, which contains a five-coordinated titanium complex (Ti[O(CH2)3CH3]3Cl·H2O), are investigated using density functional theory calculations. Initially, the complex is stabilized owing to dimer formation through molecular interactions. Subsequently, stabilization occurs due to OH bridge formation upon butanol elimination. The two dimers then unite to form [[Ti[O(CH2)3CH3]2Cl·OH]2]2 owing to the molecular interactions between the butoxy groups.

Effect of Concentrated and Dilute Hydrochloric Acid on Tooth Morphology: A Forensic Study

Introduction: Teeth are the most durable structure present in our human body because of the presence of enamel which persist and resist destruction more than any other bony structure. Hard nature with high amount of resistance of tissues present in the tooth prevents any destruction which increases the lifespan of the tooth.
 Aim: The main aim of this study is to observe the changes in tooth morphology when immersed in dilute and concentrated hydrochloric acid.
 Materials and Methods: Non-caries teeth extracted due to periodontal reasons were used from the department of oral and maxillofacial surgery. The tooth added to alternate dilute and concentrated hydrochloric acid was observed till 6th day and the changes were noted along with the photographs as observations.
 Results: The tooth left in concentrated HCl showed rapid dissolution and was completely dissolved within 24 hours. Tooth left in dilute HCl dissolved gradually and showed less dissolution when compared to concentrated HCl.
 Conclusion: Most durable teeth also undergo erosion and dissolution when placed in dilute HCl and concentrated HCl. Teeth act as a major clue in the field of forensic odontology.

Interaction of 5-arylfurfurals with malononitrile dimer

The interaction of 5-arylfurfurals with dimer malononitrile was studied. A number of previously unknown 3-amino-2,4-dicyano-5-(5-arylfuran-2-yl) -penta-2,4-dienenitriles were obtained, which were investigated in the cyclocondensation reaction with dimedone. The reaction was performed by heating the reagents in ethanol in the presence of piperidine. The reaction was monitored by TLC (eluentbenzene–acetone, 4:1 by volume). It was found that the cyclocondensation reaction proceeds with the formation of pyran and pyridine cycles – fragments of 9-oxa-1-aza-anthracene. The structure of the obtained compounds was confirmed by 1 H NMR spectra. 1 H NMR spectra were recorded on a Bruker instrument with an operating frequency of 400 MHz, solvent – DMSO- d 6 . Chemical shifts are given relative to the solvent signal (DMSO, 2.50 ppm). General procedure of obtaining 3-amino-2,4-dicyano-5-(5-aryl-furan-2-yl)-penta-2,4-dienenitriles ( 1 ). A mixture of 0.003 mol of 5-arylfurfural, 0.003 mol of malonodinitrile dimer and 4 drops of piperidine in 20 ml of ethanol was heated on a boiling water bath until the precipitate dissolved. After cooling, formed precipitate was filtered off and recrystallized from ethanol–DMF (10:1). Synthesis of 2,4-diamino-7,7-dimethyl-5-oxo-10-(5-aryl-furan-2-yl)-6,7,8,10-tetrahydro-5 H -9-oxa-1-aza-anthracene-3-carbonitriles ( 2 ). A mixture of equimolar amounts of substances ( 1 ) and dimedone (0.0014 mol), 0.03 mol of piperidine in 15 ml of ethanol was boiled until complete dissolution of the precipitate. The reaction mixture was cooled, neutralized with concentrated hydrochloric acid. The formed precipitate was filtered off, washed with water and recrystallized from ethanol. Keywords: 5-arylfurfurals, malonodinitrile dimer, dimedone, cyclocondensation reactions, 9-oxa-1-aza-anthracene derivatives.

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ ДИНАМИЧЕСКИХ СВОЙСТВ КОРРОЗИОННО-ПОВРЕЖДЕННЫХ СЖАТЫХ ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ

There are practically no results of experimental studies of elements made of compressed reinforced concrete damaged by corrosion in the scientific literature. As a result, it is almost impossible to reliably assess the state of deformation-deformation of these structures, especially under dynamic loads. For experimental studies, 37 samples of reinforced concrete were made-columns of square cross-section with dimensions of 100x100 mm, height of 700 mm. Local corrosion damages of concrete and reinforcement were created in reinforced concrete samples, while a concentrated (37%) hydrochloric acid (HCL) solution was used as an aggressor to accelerate the corrosion of elements. The article describes experimental studies on changing the dynamic properties of reinforced concrete elements that undergo corrosion during eccentrically compression. Based on strain gauge data, it was found that corrosion damage leads to a decrease in the height of the compressed concrete section by reducing the cross-section of the stretched reinforcing bars, as well as to the lack of joint work of reinforcing bars with concrete. According to strain measurement data, deformations of uncompressed and undamaged sections were obtained, which showed that the deformation diagrams fundamentally differ in their contour. The results obtained as a result of the study of the nature of deformation of reinforcement and concrete allowed us to assess the state of deformation stress of damaged and non-corroded structures according to the parameter ne-1 / r (curvature). The effect of corrosion damage on the nature of destruction of eccentrically compressed elements has been established.

Synthesis of defected UIO‐66 with boosting the catalytic performance via rapid crystallization

AbstractDue to environmental and health concerns, it is very important to develop high activity oxidative desulfurization (ODS) catalyst for petroleum purification. Recently, defect engineering of metal organic frameworks (MOFs) to generate a large number of unsaturated catalytic active sites is a very promising approach. Defective MOF has good research value as ODS catalyst. Here, UIO‐66 with lots of defects can be prepared by rapid crystallization using concentrated hydrochloric acid as a modulator. The prepared UIO‐66 material has good industrial applicability due to its low synthesis temperature (100°C), short synthesis time (20–30 min), large‐scale preparation, and excellent catalytic performance (dibenzothiophene can be entirely removed in 6 min under the optimal catalytic conditions [25‐mg catalyst, 60°C, O/S 7.5]). The obtained material exhibits not only extraordinary ODS activity of 37.6 mmol h−1 g−1 but also good cycle stability for the removal of DBT (in 7 cycles without significant loss of activity, greater than 90.2%). And for large space volume 4,6‐DMDBT, it also shows excellent catalytic performance. The ODS mechanism of defect UIO‐66 for DBT is explored, and it proves that hydroxyl radicals and superoxide radicals are generated and play a critical role in ODS reaction. The excellent catalytic performance of defect UIO‐66 gives mainly the credit to the abundant defect sites, large specific surface area, and pore volume.

METHOD OF QUANTITATIVE DETERMINATION OF THE SUM OF TANNINS IN EUTERPE OLERACEA FRUITS

Fruits of Euterpe oleracea are widely used in foreign medical practice as an antioxidant. The fruits of Euterpe contain tannins. The most common method of quantitative determination of tannins is spectrophotometry. The purpose of this work is to determine the content of the sum of tannins in the fruits of Euterpe by spectrophotometry
 Quantitative determination of the amount of tannins in the fruits of Euterpe by direct spectrophotometry was carried out. To confirm the presence of tannins in the fruits of Euterpe, qualitative reactions were used (1% solution of iron-ammonium alum, 1% solution of vanillin in concentrated hydrochloric acid). The presence of tannins was confirmed by direct spectrophotometry in extracts from euterpe fruits, the analytical maxima of the studied compounds were determined at about 282±2 nm, which corresponds to the maximum absorption of catechin. The optimal conditions for the extraction of tannins from the raw materials of this plant (extractant – ethyl alcohol 40%; the ratio of "raw material – extractant" – 1 : 100; extraction time – 60 minutes; the degree of grinding of raw materials – 1.0 mm) are justified. It was determined that the average error in determining the content of tannins in the fruits of euterpe with a confidence probability of 95% is ±1.59%. It was revealed that the content of tannins in the fruits of euterpe is 8.90%.