Aqueous Hydrochloric Acid Solutions Research Articles

Potential of Bioactive Protein and Protein Hydrolysate from Apis mellifera Larvae as Cosmeceutical Active Ingredients for Anti-Skin Aging

This study aimed to extract bioactive proteins and protein hydrolysates from Apis mellifera larvae and assess their potential application in cosmetics as well as their irritation properties. The larvae were defatted and extracted using various mediums, including DI water, along with 0.5 M aqueous solutions of sodium hydroxide, ascorbic acid, citric acid, and hydrochloric acid. Subsequently, the crude proteins were hydrolyzed using the Alcalase® enzyme. All extracts underwent testing for antioxidant activities via the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and Griess assays. Anti-aging properties were evaluated in terms of anti-collagenase and anti-hyaluronidase effects. Irritation potential was assessed using the hen’s egg chorioallantoic membrane (HET-CAM) test. The results revealed that the sodium hydroxide extraction showed promising outcomes in terms of yield, protein content, and effectiveness in inhibiting hyaluronidase, with the highest inhibition at 78.1 ± 1.5%, comparable to that of oleanolic acid. Conversely, crude protein extracted with ascorbic acid and its hydrolysate showed notable antioxidant and collagenase-inhibitory activities. Remarkably, their anti-collagenase effects were comparable to those of ascorbic acid and lysine. Additionally, it demonstrated safety upon testing with the CAM. In conclusion, the findings provided valuable insights into the utilization of A. mellifera larval proteins as active ingredients with a wide range of cosmeceutical applications, particularly due to their antioxidant, anti-aging, and low irritation properties, which hold significant promise for anti-skin wrinkles.

Еlectrochemical behavior of cadmium by alternating current polarization in hydrocloric acid solution

This paper presents the results of a study of the electrochemical behavior of a cadmium electrode in aqueous solutions of hydrochloric acid under polarization by stationary and non-stationary currents and shows the possibility of synthesis of its chloride. The purpose is to develop the electrochemical behavior of cadmium under alternating current polarization in a solution of perchloric acid. Methods. During the study, it was found that when two cadmium electrodes are polarized with an alternating current of 50 Hz, their dissolution does not occur, however, when one electrode is replaced with a titanium one, cadmium is intensively dissolved. Results and discussion. The influence of the main parameters, such as the duration of electrolysis, current density, concentration and nature of the electrolyte on the electrochemical process has been studied. A schematic diagram of an installation for dissolving cadmium by polarization with a non-stationary current is proposed. It is shown that on the titanium electrode in the range of 20-80 kA/m2, the current yield of the dissolution of the cadmium electrode gradually increases, and with a current density equal to 80 kA/m2, the current yield reaches 135%. Conclusion. It is shown that with alternating current polarization, the rate of chemical dissolution of cadmium, increases with the release of hydrogen. During the experiment, with the polarization of the cadmium electrode by alternating current, the possibility of obtaining cadmium chloride was shown. Based on chemical and X-ray phase analyses, it was proved that cadmium forms compounds CdCl2∙H2O.

The effect of solvent on the formation of low-dimensional metal halides and their self-trapped exciton emission

Low-dimensional organic–inorganic hybrid metal halides, with broadband luminescence, have attracted much attention for optoelectronic applications due to their rich in structural diversity and solution processibility. However, it is still unclear about how the solvent molecules influence the optoelectronic properties of the solution processed low-dimensional metal halides. Here, we prepared five different antimony-based crystal structures, [SbCl6]3- as the metal halide octahedron and 4, 4-difluoropiperidine (DFPD+) as organic cation, by using different solvents: hydrochloric acid (HCl) aqueous solution and four organic solvents (dimethylformamide (DMF), methanol (MeOH), acetonitrile (ACN) and dimethylacetamide (DMAC)). We revealed the relation between their crystal structures and optical properties, and we found the participation of organic molecules in the crystal structure causes significant lattice distortions, which is beneficial for achieving self-trapped exciton (STE) emission. Among them, (DFPD)6SbCl9·2DMAC exhibits a remarkable photoluminescence (PL) quantum yield of approximately 90 %. The STE dynamics in (DFPD)6SbCl9·2DMAC were characterized by femtosecond transient absorption and time-resolved PL spectroscopies. Simultaneously, this study also provides new directions for expanding the application of low-dimensional luminescent metal halides: in addition to UV-LEDs, efficient and rapid detection of methanol or acetonitrile can be achieved using the raw materials, while also realizing the potential application of multi-level optical anti-counterfeiting.

Effect of pH on primary and secondary crack propagation in sandstone under constant stress (creep) loading

Time-dependent, chemically assisted crack propagation behavior in rocks is fundamental to understanding the long-term stability of civil engineering structures. In this study, we investigated the propagation of primary and secondary cracks in macrofractured sandstone in distilled water (pH = 5.6) and in an aqueous solution of hydrochloric acid (HClaq, pH = 1.82) using digital image correlation (DIC), comparing the results to those from experiments performed in air. Results show that for the macrofracture angles γ = 0 and 90°, the nucleation position r of the primary crack is not affected by pH, and always occurs at the fracture tip (r = 0) and fracture center (r = 1), respectively. For γ = 30, 45, and 60°, r increases quasi-linearly with the increase of γ in semi-log plots, and an increase in pH moves the primary crack away from the fracture tip. For a given γ, an increase in pH produces an increase in the kink angle k1 of the secondary crack. The influence of pH on secondary crack propagation is most pronounced at high γ values. As the pH increases, the location of the secondary cracks gradually turns counterclockwise with a decreasing swing range, from 37° at pH 1.82–35° at pH 5.6. The secondary crack is inclined at a maximum of 30° and 32° to the maximum principal stress direction at pH 1.82 and pH 5.6, respectively. Right-lateral shear secondary cracks with well-developed tensile tail fractures are more prevalent in higher pH environments. The comparison with dry experiments indicates that distilled water is more aggressive than HClaq. The significant loss of calcium ions in distilled water and the reduction of large pore volume fraction in HClaq are considered the main reasons for the deterioration of the pH effect.

DETERMINATION OF OPTIMAL CONDITIONS FOR EXTRACTION OF ALUMINUM OXIDE FROM KAOLIN CLAY OF CHOVDARDAGH DEPOSIT

The increasing demand for aluminum around the world is increasing interest in developing alternative technologies for the production of alumina from non-bauxite sources, especially from clay. In this work, the extraction of aluminum from kaolin in the process of leaching using an aqueous solution of hydrochloric acid as a leaching agent is investigated. For this study, samples of burnt kaolin clay from the Chovdardagh deposit were used. Before leaching, crude kaolin was calcined; calcination achieves dehydroxylation of kaolinite, which is the main mineralogical phase of kaolin, and its transformation into metakaolin, an amorphous phase of Al-Si, from which aluminum is easily leached. The calcination of the raw kaolin used in this work was carried out at 7500C for 2 h, taking into account that these conditions were recognized as optimal in the corresponding experimental studies to achieve the maximum yield of alumina in solution. It was revealed that the leaching of kaolin clay in order to extract aluminum oxide is achieved using samples of kaolin clay calcined under the above conditions, with 20% hydrochloric acid for 2 hours at a leaching temperature of 950C. The degree of extraction of aluminum and iron oxide under these conditions is 96.7 and 94.1%, respectively

TEMPERATURE-DEPENDENT KINETICS OF ANTHOCYANINS EXTRACTION FROM RED ROSE PETALS

The red rose is one of the perspective natural resources of anthocyanins, however kinetic study for anthocyanins extraction of red rose petals is not yet elucidated. Red rose petals were dried at 303 K and ground (particle size ~ 5 mm). The petals were extracted by aqueous acid solutions using conventional solid-liquid extraction. The efficiency of 0.1 M aqueous solutions of acids as extractants towards red rose anthocyanins was studied and it can be arranged in the following row: citric acid < acetic acid < hydrochloric acid. Kinetic investigations focusing on the temperature effect on solid-liquid extraction of anthocyanins from petals of red rose were performed at three temperatures (293, 313, and 333 K). Kinetic curves were obtained using an aqueous solution of hydrochloric acid. It was found that the rate of extraction of anthocyanins was very fast at the beginning, but it began to slow down after 60 minutes for all temperatures. The experimental kinetic curves of the extraction of anthocyanins at different temperatures were obtained and analyzed using common empirical kinetic models (the first-order, second-order kinetic models, the Peleg model, and the power-law model). The second-order kinetic model provided the best agreement with the experimental results in terms of statistical parameters (coefficient of determination (R2) and average relative error (ARE)) than other studied models. As temperature increases, the second-order rate constant values and the initial extraction rate values also increased. The second-order rate constants were used to evaluate the activation energy of extraction. The calculated activation energy of the anthocyanin extraction is 39.3 kJ/mol, which is an indication of an endothermic process. Obtained data can be used to predict the extraction of anthocyanins from red rose petals.

Evidence of Chlorotellurate(IV) – Hydroxochlorotellurate(IV) species equilibrium upon dissolution of tellurite glasses in aqueous hydrochloric acid: A Raman spectroscopic study

Raman spectroscopy has been used to elucidate the structure of tellurium (IV) oxide and its binary mixtures with thallium oxide both in the glassy state and in aqueous hydrochloric acid solutions. The addition of Tl2O in pure TeO2 glass results in the progressive transformation of TeO4 trigonal bipyramid (tbp) to TeO3 trigonal pyramid (tp) units in agreement with the literature findings. Thallium oxide acting as a modifier for the tellurite network, reduces the functionality of the initial unit and lowers the continuous network rigidity. The spectral changes upon dissolution of the 0.2Tl2O-0.8TeO2 glass in aqueous hydrochloric acid solution have also been measured revealing that the main structural units of the glass structure did not survive in a solution state and the connectivity of the glass network has completely collapsed. The systematics and the concentration dependence of the spectra acquired from different solutions indicate the presence of several chlorotellurate(IV) and hydroxochlorotellurate(IV) ionic species. The spectroscopic data are interpreted in such a way in order to indicate a dynamic equilibrium between the TeCl62− anion and the TeCl4(OH)− species. A combined analysis of the polarized and depolarized scattered intensity is presented here which aimed at elucidating the presence of additional species including the TeCl4(OH)22− and TeCl3(OH) species, respectively. The proposed model is discussed in the framework of the current phenomenological status of the field.

Determination of endogenous phenolic compounds in honey by HPLC-MS/MS

To achieve the highly selective, sensitive, and universal analysis of endogenous phenolic compounds in honey, 24 phenolic compounds were simultaneously analyzed using high-performance liquid chromatography coupled with tandem mass spectrometry. Honey samples were extracted using ethyl acetate and 0.01 mol/L hydrochloric acid aqueous solution in two stages and cleaned by hydrophilic-lipophilic balanced columns. The 24 analytes exhibited good linearity, with coefficients of determination (R2) higher than 0.99. The limits of detection and quantitation were 0.2–1.0 and 0.6–3.0 μg/kg, respectively; the recoveries were 71.5%–115.2%, and the intra- and inter-day relative standard deviations were both <10%. Nine phenolic compounds, namely, 4-hydroxybenzoic acid, rutin, vanillic acid, hyperoside, p-coumaric acid, syringic acid, caffeic acid, ferulic acid, and gallic acid, were detected and quantified in honey samples collected from the Xinjiang province of China. The results show that the method was simple, highly sensitive, and accurate as well as suitable for the simultaneous analysis of endogenous phenolic compounds in honey samples.

Metal-Free Construction of Multisubstituted Indolizines via Intramolecular Amination of Allylic Alcohols.

An intramolecular amination of allylic alcohols is developed as an efficient and general access to biologically important multisubstituted indolizines and their variants. Two metal-free synthetic platforms including using aqueous hydrochloric acid solution as the solvent and p-toluenesulfonic acid as the catalyst have been established, enabling the divergent synthesis of these valuable compounds in high yields.

Spectral signatures of excess-proton waiting and transfer-path dynamics.

Signatures of solvated excess protons in infrared difference absorption spectra, such as the continuum band between the water bend and stretch bands, have been experimentally known for a long time and have recently been used to analyze protonation dynamics in photoactive proteins. However, the theoretical basis for linking spectral signatures with the microscopic proton-transfer mechanism so far relied on normal-mode analysis. We analyze the excess-proton dynamics in ab initio molecular-dynamics simulations of aqueous hydrochloric acid solutions by trajectory-decomposition techniques. The continuum band in the 2000 cm−1 to 3000 cm−1 range is shown to be due to normal-mode oscillations of temporary H3O+ complexes. An additional prominent peak at 400 cm−1 reports on the coupling of excess-proton motion to the relative vibrations of the two flanking water molecules. The actual proton transfer between two water molecules, which for large water separations involves crossing of a barrier and thus is not a normal mode, is characterized by two time scales: Firstly, the waiting time for transfer to occur in the range of 200 fs to 300 fs, which leads to a broad weak shoulder around 100 cm−1, consistent with our experimental THz spectra. Secondly, the mean duration of a transfer event of about 14 fs, which produces a rather well-defined spectral contribution around 1200 cm−1 and agrees in location and width with previous experimental mid-infrared spectra.

Стресс-тесты антраценпроизводных растительного происхождения

Objective: to study the stability of solutions of standard samples of sennoside B and glucofrangulin A by stress tests using high performance liquid chromatography (HPLC). Materials and methods. The objects of the study were solutions of standard samples of sennoside B, as well as glucofrangulin A. Stress agents were 0.5M aqueous solution of copper (II) chloride (CuCl2), 0.5M aqueous solution of iron (III) chloride (FeCl3), 0.1M aqueous solution of hydrochloric acid (HCl), as well as 0.1M aqueous solution of sodium hydroxide (NaOH) and a solution of hydrogen peroxide (H2O2) 3%. The study was carried out using an Agilent 1100 liquid chromatograph. For this purpose, a Zorbax SB-C18 reverse-phase column (4.6×250 mm, 5 µm) was used. Elution of the mobile phase (acetonitrile and highly purified water, which was adjusted to pH 2 with phosphoric acid) was carried out in a gradient mode. Detection was carried out at wavelengths of 360 nm and 435 nm. Results. It was found that a solution of a standard sample of glucofrangulin A is stable for 14 days under the influence of 0.1M aqueous solution of HCl and 0.1M aqueous solution of NaOH, as well as 0.5M aqueous solution of FeCl3 and 3% H2O2 solution. When a solution of a standard sample of glucofrangulin A interacts with a 0.5M aqueous solution of CuCl2, its destruction is observed. When a standard sample of sennoside B reacts with a 3% H2O2 solution and a 0.5M aqueous CuCl2 solution, it remains stable. When interacting with other stress agents, its destruction occurs. Conclusion. The results obtained on the stability of solutions of standard samples of anthracene derivatives determine the main physico-chemical factors that cause their destruction, which can be taken into account when validating analytical methods, justifying the conditions of storage, packaging and processing of medicinal plant materials that contain anthracene derivatives.

STUDYING THE TECHNOLOGICAL POSSIBILITY OF OBTAINING SILICON DIOXIDE AND SEPARATION OF METALS FROM TECHNOGENIC ORE FORMATIONS

A combined pyro-hydrometallurgical technological method for obtaining silicon dioxide of. technical purpose and metal concentrates from technogenic ore formations resistant to chemical reagents is shown. The smelting of the raw materials prepared for the processing of technogenic formations is carried out by combined reagents, after which the melt formed is leached with an aqueous solution of hydrochloric acid under gel-like conditio¬ns¬. The reduced silicic acid is leached with a weak aqueous solution of hydrochlo¬r¬i¬c acid in order to remove impurities, and to be converted into silicon dioxide, it is subjected to heat treatment in atmospheric air. As a result of the process, the metals contained in technogenic formations are divided into solid and liquid concentrates.

STRUCTURE OF CORNEL CORNEL FRUITS ANTHOCYANS (CORNUS MAS)

The composition of common dogwood fruits anthocyanins was determined using reverse-phase HPLC with spectrophotometric and mass spectrometric detection. A procedure for determining the structure of individual components of extracts including 3-galactosides of delphinidin, cyanidin and pelargonidin and 3-robinobiosides (3-rhamnosylgalactosides) of cyanidin and pelargonidin has been described. It was found that the content of delphinidin-3-galactoside, as well as both 3-robinobiosides, may be insignificant when cyanidin and pelargonidin 3-galactosides predominate. For the studied fruits, the level of accumulation of anthocyanins can reach (depending on color intensity) 46 mg per 100 g of fresh fruit, while the concentration of anthocyanins in the peel of fruits is significantly higher - more than 390 mg per 100 g. When developing an exhaustive extraction of anthocyanins, a peculiarity of dogwood fruits was established, which consists in the fact that extraction of anthocyanins by 0.1 M aqueous hydrochloric acid solution, unlike a large number of other natural sources studied, is practically impossible. The problem can be solved only by extraction with acidified aqueous-alcoholic mixtures when the ethanol content in the extractant is more than 30 vol.%, which indicates the high affinity of fruit pulp components to anthocyanins.

A high temperature retarded acid based on self-assembly of hydrophobically associating polymer and surfactant

Development of the novel retarded acid using in high temperature acidizing and acid fracturing remains an important challenge. Terpolymer-hydrophobically associating polyacrylamide (HA-PAM) with more content of hydrophobic monomer than conventional water-soluble association polymers designed to use as acid thickener was synthesized through aqueous solution polymerization with polymerizable cationic surfactant. The polymer structure was characterized by FT-IR and 1H NMR. The viscous performances in 20 % hydrochloric acid aqueous solution of HA-PAMs synthesized with different amounts of cationic hydrophobic monomer were investigated. The effects of different concentrations of HA-PAM on the viscous performance were also investigated. To further increase the viscosity, a selected surfactant was added to the thickened acid formed by synthesized HA-PAM to form a physically associating acid through micelle and HA-PAM associating interaction. Thickening performance, viscoelasticity, shearing resistance and temperature resistance for physically associating acid was evaluated by Rheometer. The viscosity of physically associating acids formed by the synergy of designed acid thickening polymers and surfactant exceeded 50 mPa·s under 123 °C, which demonstrated the self-assembly acids meet the requirements for high temperature acid fracturing. The designed acid thickening polymers and novel self-assembly acids by physical association have potential applications in high temperature acidizing and acid fracturing.

Cathodic Corrosion Inhibition of Steel by Musa Paradisiaca Leave Extract

It is reported here that the phytochemicals present on the surface of the Musa paradisiaca (MPL) prevent water and other corroding agents from having direct access to the surface of mild steel. These phytochemicals were extracted from the MPL using 70% Ethanol solution and Weight Loss experiment was carried out with variation of temperature, time and concentration HCl and that of the MPL extract in % v/v. The inhibition eFFect of M. paradisiaca leaves of mild steel in aqueous solutions of Hydrochloric acid were investigated at 25, 35, 45 and 60 oC being immersed simultaneously and independently in the acid medium over a period of 12, 24, 48, and 72 hours. A protecting film appeared on the metal surface by the MPL extract via electron donation, hence, acting as the cathode. The temperature and immersion time were inversely proportional to inhibition effciency while concentration of MPL is directly proportional. FT-IR of the extract showed oxygen and nitrogen containing functional groups which are the general characteristics of a typical corrosion inhibitor, while the Gas Chromatography–Mass Spectrometry (GC–MS) investigation revealed different biomolecules thus suggesting that the plant extract consists of different molecules.

Anticorrosive Polymeric Coatings

Abstract In order to improve the anticorrosion protection properties, polypyrrole thin films were deposited on silicon steel plates. The anticorrosive protection effect of the polypriol coating was evaluated by electrochemical measurements in two different aqueous solutions of potassium chloride and hydrochloric acid. Polypyrrole-coated silicon steel plates were immersed for one and seven days, respectively. The obtained results show that the thin layer of polypyrrole ensures effective protection of silicon steel against corrosion, especially in aqueous potassium chloride solution.

Spectral signatures of excess-proton waiting and transfer-path dynamics in aqueous hydrochloric acid solutions

The theoretical basis for linking spectral signatures of hydrated excess protons with microscopic proton-transfer mechanisms has so far relied on normal-mode analysis. We introduce trajectory-decomposition techniques to analyze the excess-proton dynamics in ab initio molecular-dynamics simulations of aqueous hydrochloric-acid solutions beyond the normal-mode scenario. We show that the actual proton transfer between two water molecules involves for relatively large water-water separations crossing of a free-energy barrier and thus is not a normal mode, rather it is characterized by two non-vibrational time scales: Firstly, the broadly distributed waiting time for transfer to occur with a mean value of 200–300 fs, which leads to a broad and weak shoulder in the absorption spectrum around 100 cm−1, consistent with our experimental THz spectra. Secondly, the mean duration of a transfer event of about 14 fs, which produces a rather well-defined spectral contribution around 1200 cm−1 and agrees in location and width with previous experimental mid-infrared spectra.

Use of a Polymer Gel for Killing a High-Temperature and High-Pressure Gas Well

Summary In the processes of oil and gas drilling, gas easily invades wellbores and adversely influences the safety in high-pressure gas reservoir drilling activities. In this study, a polymer gel was prepared for well killing in high-pressure gas reservoirs. The gelation performance of the gel under different conditions was experimentally examined. The gel can maintain high shear resistance, high-temperature resistance, and high-temperature long-term stability at 160°C and is thus suitable for the long-term isolation of high-temperature formations. The gel is sensitive to high concentrations of salt ions and must be prepared in the field using saline solutions with Na+ and Ca2+ concentrations lower than 20 000 and 500 mg/L, respectively. The gel can be easily oxidized and disintegrated by acidic solutions. The gel disintegration rate may reach 100% when subjected to ammonium persulfate and hydrochloric acid aqueous solutions at 160°C. Moreover, the polymer gel performance in application scenarios was examined. The gel density can be increased using barite and magnetite. The water loss percentage of the gel is less than 10% at 160°C, rendering its use suitable for well killing in openhole intervals, especially in water-sensitive formations such as mudstone and shale. The permeability recovery of the gas reservoir core is more than 90% when gasflooding is performed with oxidative degradation of the gel. The gel exhibits excellent well kill capacity, with a maximum value of 8.8 MPa/100 m after aging at 160°C for 3 days. Successful field test was conducted in the Tarim Basin, Xinjiang, China, which indicates that the gel can be used for well killing in high-temperature and high-pressure gas reservoirs.

Removal of aluminum to obtain high purity gadolinium with pyridinium-based ionic liquids

As an associated element, aluminum (Al(III)) has a negative effect on the purity of rare earth gadolinium (Gd(III)). Three pyridinium-based ionic liquids ([(CH2)nCOOHpyr][NTf2], n = 3, 5, 7) were proposed as the solvent in liquid-liquid extraction for separation of the Al(III) impurity from Gd(III) in this study. The effect of pH value of the aqueous phase, diluent type, extraction time and temperature on the extraction separation of Al3+ from GdCl3 solution were investigated systemically. The results show that the separation factor β of Al(III)/Gd(III) is up to 340 by adjusting the pH value of the aqueous phase which is higher than the values of other reported systems, and the removal efficiency of Al(III) could reach 97.1%, with the recovery efficiency of Gd(III) of 85.6% through one-time extraction using a mixture of ionic liquids [(CH2)7COOHpyr][NTf2]-[C4mim][NTf2] as the extractant. The slope analysis and infrared spectroscopic characterization indicated that the extraction mechanism of Al(III) by the [(CH2)7COOHpyr][NTf2]-[C4mim][NTf2] system follows the cation exchange mechanism. After the extraction, 0.08 mol/L hydrochloric acid aqueous solution was used to strip Al(III) from the ionic liquid phase, and complete recovery of Al(III) could be realized. The extraction efficiency of the [(CH2)7COOHpyr][NTf2]-[C4mim][NTf2] system for separation of Al(III) is still more than 97.8% after recycling for 8 cycles.

Study of the Addition Mechanism of 1H-Indazole and Its 4-, 5-, 6-, and 7-Nitro Derivatives to Formaldehyde in Aqueous Hydrochloric Acid Solutions.

The reaction of NH-indazoles with formaldehyde in aqueous hydrochloric acid has been experimentally studied by solution and solid-state nuclear magnetic resonance (NMR) and crystallography. The mechanism of the formation of N1-CH2OH derivatives was determined. For the first time, 2-substituted derivatives have been characterized by multinuclear NMR. Theoretically, calculations with gauge-invariant atomic orbitals (GIAOs) at the Becke three-parameter (exchange) Lee–Yang–Parr B3LYP/6-311++G(d,p) level have provided a sound basis for the experimental observations. The first X-ray structures of four (1H-indazol-1-yl)methanol derivatives are reported.