Search

In this study, UiO-66-NH2 nanoparticles were synthesized via a hydrothermal method, using acetic acid and hydrochloric acid as modulators to optimize the specific surface area and pore width. Oxytetracycline (OTC) was chosen as the test compound to evaluate the adsorption efficiency of UiO-66-NH2.The material was thoroughly characterized under varying conditions, and the adsorption mechanism was systematically explored through adsorption kinetics, isotherms, and thermodynamic analyses. The results demonstrated that UiO-66-NH2 exhibited a high OTC adsorption capacity, achieving a maximum of 312.5 mg g−1 under optimal conditions. XRD, TGA, and BET analyses revealed that acetic acid and hydrochloric acid significantly improved the crystallinity and thermal stability of UiO-66-NH2, increasing the specific surface area from 8.023 m2 g−1 to 998.663 m2 g−1 and reducing the pore width from 18.783 nm to 2.129 nm. FTIR, XPS, adsorption kinetics, and isotherm studies indicated that the main forces driving OTC adsorption by CMC-Fe were hydrogen bonding, π–π stacking, weak electrostatic interactions, and pore filling. Cyclic adsorption experiments further demonstrated the excellent reusability of UiO-66-NH2. In summary, the use of acetic acid and hydrochloric acid significantly increased the specific surface area of UiO-66-NH2, exposing more adsorption sites and playing a critical role in pollutant removal. [ABSTRACT FROM AUTHOR]

With the increasing focus on sustainable development, the exploration of renewable and environmentally friendly resources for product synthesis has become paramount. This study aims to investigate the production of dihydroxystearic acid through the in situ hydrolysis of epoxidized oleic acid. Epoxidation of oleic acid was achieved through the utilization of in situ generated performic acid, resulting in the production of epoxidized oleic acid. The synthesis of performic acid involved the combination of formic acid as an oxygen carrier and hydrogen peroxide as an oxygen donor. A maximum epoxide yield of 65% was attained at an optimum reaction time of 30 min. Hydrochloric acid was found to be the most efficient catalyst. A kinetics study was also done using the genetic algorithm to find the reaction rate of dihydroxystearic acid production. The difference between simulation and experimental results was less than 0.1%, which is insignificant. The findings highlight the potential of utilizing renewable resources for the synthesis of high-value compounds, promoting a greener and more sustainable future. [ABSTRACT FROM AUTHOR]

This research helps with the creation, assessment, and characterization of a new hybrid protective coating for carbon steel alloy in acid conditions. The findings of this study will be useful for both chemical and petrochemical companies as well as scientists. This study aims to protect C-steel in acid pickling solution 1.0M HCl and formulate new hydrophobic protective hybrid organic–inorganic coatings from biopolymers chitosan and plant resin guar gum. Eight coating samples of chitosan in the absence and the presence of guar gum, silica and two heterocyclic compounds are prepared at feasible operational conditions using hot melt method. The aiding additives improved compatibility between coating constituents as confirmed by using different methods of analysis. This new processing approach has addressed the problems of using chitosan in corrosion control such as solubility in acid media and low mechanical strength. Coating samples of chitosan and its composites with the heterocyclic compounds (2-Hydrazinyl-6-methyl-4, 5-dihydro pyrimidine-4-on) or (2-Hydrazinyl-6-phenyl-4, 5-dihydro pyrimidine-4-on) are potent biocides. Coating shifts corrosion potential of carbon steel by 30 mV to more noble direction relative to the active potential 520 mV of bare carbon steel surface. Impedance and polarization measurements indicate that coating samples protect metal surface as mixed-type inhibitor by adsorption mechanism. There is a good agreement between percentages protection %P of coating calculated using the values of charge transfer resistance, Rct, and corrosion current density, icorr. All %P values are above 99% for all coating samples. Guar gum plant resin increases gloss of the coating film. Silica fills the pores in the polymeric film and increases the stuffiness of the polymeric coating film by modifying the particle size. All coated samples have high contact angle ranging from 150° to 165° indicating low wettability and high hydrophobicity of coating film on the metal surface. [ABSTRACT FROM AUTHOR]

As a part of efforts to develop a laboratory soil-resin incubation technique to assess soil phosphorus (P) release by mixing resin beads directly with soil acting as a P sink to mimic plant root uptake, selecting a suitable type of anion exchange resin (AER) is essential. Thus, five types of strong basic AER in bicarbonate (HCO3)—form were evaluated for their ion exchange characteristics in salt solutions. The P adsorption study was conducted under four sulfate (SO42-) concentrations (0.1, 0.01, 0.001, and 0.0001 M) at each of three fixed concentrations (0.21, 0.62, and 2.06 mM) of potassium dihydrogen phosphate (K2HPO4). Results showed that adsorbed P was quantitatively extracted from the resins with dilute hydrochloric acid (1 M, HCl). Also, increasing the SO42- concentration dramatically decreased the adsorption of P by the resins, with little difference between a one- and seven-day equilibration period. All five resins behaved similarly at higher concentrations of SO42-, but at lower concentrations of SO42-, the HCO3—form Amberlite I-6766 resin had a higher affinity for P than other Dowex resins. There was much greater P adsorption to the resin at solution pH > 7.2, which suggests hydrogen phosphate (HPO42-) to be much more strongly adsorbed than dihydrogen phosphate (H2PO4−). Also, the Amberlite resin has more favorable physical properties with a granular structure, lower density, and ease of handling and separation from soil, which was chosen for subsequent soil studies. [ABSTRACT FROM AUTHOR]

In the pickling process and acidizing program for oil wells, the acidic corrosion of metals is a problem that needs to be addressed. Various acid corrosion inhibitors have been studied and used to mitigate the acidic corrosion of carbon steel. In this paper, the corrosion inhibition of 2‐aminobenzothiazole (2 N‐BT), 2‐amino‐4‐hydroxybenzothiazole (2 N4O‐BT), and 2‐amino‐6‐hydroxybenzothiazole (2 N6O‐BT) on carbon steel in 0.5 mol/L HCl was investigated using electrochemical and quantum chemical methods. All three molecules exhibited corrosion inhibition effects. Compared to 2 N‐BT, 2 N4O‐BT and 2 N6O‐BT showed less sensitivity to the environmental conditions and the surface state of the metal. Among them, 0.0010 mol/L 2 N6O‐BT demonstrated the highest and most persistent corrosion inhibition, exhibiting a mixed inhibition mechanism with cathodic inhibition dominance. The adsorption of 2 N6O‐BT on the carbon steel surface was found to be non‐uniform, preferentially adsorbing at certain active sites on the surface, following Freundlich‐Langmuir thermodynamic characteristics. It showed initial strongly adsorbed points and weakly adsorbed regions. With continued adsorption of 2 N6O‐BT, the differences between strongly adsorbed points and weakly adsorbed regions decreased. The introduction of hydroxyl groups, especially in 2 N6O‐BT, extended the negative potential region and enhanced the coordination activity of the molecule, generating the orbital distribution that was advantageous to flat adsorption and the formation of feedback bonds. This provided a molecular structural basis for the excellent corrosion inhibition properties of 2 N6O‐BT. [ABSTRACT FROM AUTHOR]

Germanane (GeH) and silicane (SiH), members of the Xanes family, have garnered significant attention as 2D materials due to their diverse properties, which hold promise for applications in electronics, optoelectronics, energy storage, and sensing. Typically, highly concentrated hydrochloric acid (HCl) or hydrofluoric acid (HF) is employed in the synthesis of these Xanes, but both routes are problematic due to slow kinetics and safety concerns, respectively. Here for the first time, a faster and safer method is demonstrated for Xanes synthesis that harnesses the generation of HF “in situ” using a solution of HCl and lithium fluoride (LiF) salt, overcoming the key challenges of the conventional methods. A variety of characterization techniques to establish a baseline is utilized for both Xanes and to provide a holistic knowledge regarding this method, the possible consequences of this approach, and the possibility of applying it to other layered Zintl phases. The novel synthesis protocol results in high‐quality GeH and SiH with bandgaps (Eg) of 1.75 and 2.47 eV respectively, highlighting their potential suitability for integration into semiconductor applications. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT A new 1,2,3‐triazole functionalized ferrocene (1,2,3‐TAFc) produced by Cu(I)‐catalyzed click reaction was investigated as positive electrolyte for aqueous organic flow batteries (AOFBs). The molecule is highly soluble in 1 M hydrochloric acid and displays high electrochemical reversibility. 1,2,3‐TAFc demonstrated good stability during cycling with a low capacity decay (0.011%/cyc, 3.0%/day) and high Coulombic efficiency (99.4%) over 280 cycles when tested in a flow battery at low concentration. This low capacity decay was attributed to the instability of ferrocene. These findings indicate that a stable and water‐soluble catholyte for AOFBs can be obtained with structural modifications of 1,2,3‐TAFc. [ABSTRACT FROM AUTHOR]

The extraction of rare earth elements (REEs) from mineral resources is of significant global importance due to their critical role in modern technologies. This study focuses on the leaching behavior of artificial cerium and lanthanum phosphates using nitric, sulfuric, and hydrochloric acids under varying conditions of acid concentration and temperature. Our experiments demonstrated that the maximum extraction efficiency of lanthanum and cerium was achieved with nitric acid solutions at concentrations of 12.5 mol/dm3, with 85.0% and 79.1% extraction efficiency, respectively. The leaching mechanism involved the protonation of phosphate anions, which disrupted the phosphate matrix, facilitating the dissolution of lanthanum and cerium into solution. Sulfuric acid, although less effective at room temperature, proved to be the most thermodynamically favorable leaching agent at higher temperatures due to the formation of stable sulfate complexes. Additionally, hydrochloric acid displayed high selectivity for cerium extraction, although its applicability is limited by complexation and environmental concerns. This study offers new insights into optimizing REE recovery from phosphates, demonstrating the advantages of sulfuric acid for industrial-scale leaching processes due to its economic and thermodynamic benefits. The novelty of this work lies in its systematic comparison of the three acids' effects on REE extraction, providing a comprehensive framework for selecting optimal leaching agents based on specific operational conditions. [ABSTRACT FROM AUTHOR]

Regeneration can effectively restore the adsorption capacity of adsorbents, enabling sustainable adsorption–desorption–adsorption cycles to be maintained. The regeneration of waste adsorbents has been extensively documented. However, there is few research on the adsorption properties and the mechanism after regeneration. The regeneration of aluminum-based phosphorus-inactivation agent (Al-PIA) and recovery of phosphate from Al-PIA were achieved in the previous study. Therefore, this study determined the mechanism and effects of Al-PIA recycling on phosphate removal, following regeneration for 30 min using 0.75 mol/L hydrochloric acid. Results show that the rate of adsorption by regenerated aluminum-based phosphorus-inactivation agent (Re-Al-PIA) was faster within the first 15 h, reaching equilibrium at around 50 h, with the rate-determining step being intraparticle diffusion. The adsorption saturation concentration of Re-Al-PIA was 6.92 mg/g, with phosphate adsorption occurring via a spontaneous, heat-absorbing, and chaotic process. Regeneration restored the phosphate removal capacity of Al-PIA. Al-PIA maintained its initial phosphate adsorption capacity after three cycles. The phosphate removal mechanisms of Re-Al-PIA were physical adsorption, electrostatic adsorption, surface precipitation, and ligand exchange. Regeneration provided favorable physical conditions for phosphate adsorption, enhancing the electrostatic adsorption capacity of the material while also restoring surface precipitation and ligand exchange for phosphate removal. These results can provide theoretical basis and technical support for the practical application of Al-PIA regeneration and a reference method for regeneration of the other phosphate removal materials. [ABSTRACT FROM AUTHOR]

The title compound, (C9H8NO)[CuCl3(C7H5NO4)]·2H2O, was prepared by reacting CuII acetate dihydrate, solid 8-hydroxyquinoline (8-HQ), and solid pyridine-2,6-dicarboxylic acid (H2pydc), in a 1:1:1 molar ratio, in an aqueous solution of dilute hydrochloric acid. The CuII atom exhibits a distorted CuO2NCl3 octahedral geometry, coordinating two oxygen atoms and one nitrogen atom from the tridentate H2pydc ligand and three chloride atoms; the nitrogen atom and one chloride atom occupy the axial positions with Cu—N and Cu—Cl bond lengths of 2.011 (2) A˚ and 2.2067 (9) A˚, respectively. In the equatorial plane, the oxygen and chloride atoms are arranged in a cis configuration, with Cu—O bond lengths of 2.366 (2) and 2.424 (2) A˚, and Cu—Cl bond lengths of 2.4190 (10) and 2.3688 (11) A˚ . The asymmetric unit contains 8- HQ+ as a counter-ion and two uncoordinated water molecules. The crystal structure features strong O—H...O and O—H...Cl hydrogen bonds as well as weak interactions including C—H...O, C—H...Cl, Cu—Cl...π, and π–π, which result in a three-dimensional network. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing involving the main residues are from H...Cl/Cl...H interactions, contributing 40.3% for the anion. Weak H...H contacts contribute 13.2% for the cation and 28.6% for the anion. [ABSTRACT FROM AUTHOR]

Gels are used in the oilfield. For example, during oil recovery, organogels are pumped underground into fractures within oil‐bearing rock, so as to block fluid flow. However, after several days, the gels must be degraded (liquefied) to enable oil extraction through the fractures. To degrade gels, 'degrading agents' as well as external stimuli have been examined. Here, a concept is demonstrated that avoids external agents and stimuli: self‐degrading organogels based on the self‐assembly of molecular gelators. The gels are a) extremely robust (free standing solids) at time t = 0 and (b) degrade spontaneously into a sol after a set time t = tdegr that can be minutes, hours, or days. These properties are achieved by combining two readily available molecules — the organogelator (1,3:2,4)‐dibenzylidene sorbitol (DBS) and an acid (e.g., hydrochloric acid, HCl) — in an organic solvent. DBS self‐assembles into nanoscale fibrils, which connect into a 3‐D network, thereby gelling the solvent. The acid type and concentration set the value of tdegr at a given temperature. Degradation occurs because the acid slowly hydrolyzes the acetals on DBS, thereby converting DBS into small molecules that cannot form fibrils. DBS gels with a pre‐programmed "degradation clock" can be made with both polar and non‐polar organic solvents. The concept can be a game‐changer for oil recovery as it promises to make it safer, more efficient, and sustainable. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acute corrosive acid ingestion presents significant challenges in clinical and forensic pathology due to its severe and often fatal outcomes. This case series examines four autopsies involving fatal acid ingestion: three cases of hydrochloric acid (HCl) poisoning and one case of sulfuric acid (H2SO4) poisoning. Each case provides detailed autopsy findings, focusing on macroscopic and microscopic pathological changes. The first three cases of HCl poisoning revealed extensive tissue damage characterized by coagulative necrosis, particularly affecting the esophagus, stomach, and duodenum. Histological examination showed dense inflammatory infiltrate, submucosal edema, and significant hemorrhage, with patchy necrosis observed in the liver and kidneys. Pulmonary findings included alveolar edema and hemorrhage. The fourth case, involving H2SO4 ingestion, demonstrated more severe injuries with transmural necrosis and extensive hemorrhagic infiltration in the esophagus. The stomach exhibited full-thickness necrosis with a pronounced sulfurousodor, indicating severe chemical injury. Histopathological findings included extensive tissue dehydration and charring, with severe alveolar edema and hemorrhage in the lungs and extensive necrosis in the liver and kidneys. Comparative analysis of the histopathological changes highlighted the differences in tissue damage caused by these two acids. HCl primarily induced superficial necrosis with relatively preserved tissue architecture, while H2SO4 caused more extensive and deeper tissue damage due to its strong dehydrating and exothermic properties. Recognizing these differences is crucial for forensic pathologists in accurately diagnosing and differentiating cases of acid poisoning, ultimately enhancing diagnostic precision and clinical outcomes. This study underscores the severe and often fatal consequences of acute acid ingestion and aims to enhance the understanding of the pathological changes associated with such poisonings, thereby improving forensic and clinical evaluations. [ABSTRACT FROM AUTHOR]

Aluminum recycling is an important step to achieve high value-added utilization of fly ash to improve the leaching efficiency of Al. In this paper, Na2CO3 was used as the flux and HCl as the leaching solution to extract Al from CFA by using the roasting activation-acid leaching process to investigate the influencing factors of the leaching rate of Al to analyze the mineral composition of the roasting products explore the activation process of CFA roasting. The experimental results showed that compared with NaF, CaO, and NaOH, the highest Al leaching rate was achieved when Na2CO3 was used as a flux, at which time the leaching rate could reach up to 81.62%, and it was about 63% higher than that of extracting Al from the fly ash using direct roasting-acid leaching method. When the roasting time is 90 min, the roasting temperature is 850°C, the CFA/Na2CO3 is 1.5, the hydrochloric acid concentration is 4 mol/L, the acid leaching temperature is 90°C, the S/L is 1:4, and the maximum leaching rate of Al is 81.62%. According to the thermodynamic theory, Na2CO3 and mullite gradually reacted with each other above 800 K to form chalcopyrite, and Na2CO3 reacted with mullite and quartz in CFA to form chalcopyrite more easily. According to the reaction kinetic model, the acid leaching process of CFA is mainly controlled by diffusion, and a semi-empirical equation is proposed to describe the whole leaching process. [ABSTRACT FROM AUTHOR]

This study systematically explores the corrosion inhibition potential of 2- acetylpyrazine for mild steel in a hydrochloric acid (HCl) solution, employing a comprehensive approach that integrates experimental weight loss measurements and Density Functional Theory (DFT) calculations. Investigating inhibitory performance across varying immersion times, inhibitor concentrations, and temperatures, our research aims to elucidate the corrosion inhibition mechanism. Numerical findings highlight a substantial inhibitory efficiency of 92.7 % at an inhibitor concentration of 0.5 mM, an immersion time of 5 hours, and a temperature of 303 K. Remarkably, the efficiency increases to 98.1 % after extending the immersion time to 48 hours at 303 K with the same inhibitor concentration. Furthermore, we demonstrate the temperature's impact on inhibition efficiency, reaching 97.3 % at 333 K with an immersion time of 5 hours and an inhibitor concentration of 0.5 mM. The Langmuir model, applied to adsorption isotherms, provides valuable insights into the adsorption behavior of 2- acetylpyrazine on mild steel surfaces. Additionally, scanning electron microscope (SEM) results indicate the formation of a protective film on the steel surface in the presence of the studied inhibitors. This combined experimental and computational approach not only enhances our comprehension of the corrosion inhibition mechanism but also emphasizes the practical viability of 2-acetylpyrazine as an effective and temperature-sensitive inhibitor in HCl environments. These findings contribute significantly to advancing corrosion mitigation strategies with potential implications for industrial applications. [ABSTRACT FROM AUTHOR]

Acid digestion is the most ideal detection method for the determination of copper in copper concentrate, which is commonly treated with hydrochloric acid and nitric acid. However, for some insoluble copper-containing material samples, there is always black residue that cannot be treated in the later stage of dissolution, and adding saturated ammonium fluoride after adjusting acidly before titration can produce dark purple flocculent precipitation, witch seriously affect the titration analysis, resulting in large deviation and inaccurate analysis results. In this study, copper-containing material waste dissolved by acid dissolution, insoluble material was filtered and separated, and the residue was analyzed and corrected. The conditions such as the amount of hydrofluoric acid and the amount of nitric acid used in the dissolution of filtered filter residue were optimized by experiments, and the final experimental method was established. The determination results were consistent with the results of laboratory outsourcing, and the relative standard deviation (RSD) was 0.060% -- 0.16%, which showed that this method was accurate, rapid, stable and reliable for the determination of copper content in copper materials in the range of 12.5%--24.5%. [ABSTRACT FROM AUTHOR]

Solvent extraction of selenium(IV) ions from highly concentrated hydrochloric acid using 0.4 mol/L Aliquat 336 dissolved in kerosene was investigated. As a modifying agent, 1-octanol (10% v/v) was added to the organic phase to avoid the third phase formation. The effect of different parameters affecting the liquid-liquid extraction of selenium(IV) such as the acid concentration, shaking time, metal ion concentration in the aqueous phase, loading capacity, diluents, and temperature, was studied. The results indicate that selenium(IV) is extracted efficiently by 0.4 mol/L Aliquat 336 dissolved in kerosene. It was noticed that the extraction increased with the increase in the acid and Aliquat 336 concentrations, reaching an extraction percentage of about 92% at 8 mol/L HCl and 97.1% at 1 mol/L extractant. The extracted organic species is postulated to be [H2SeO2Cl2.2R4NCl]org by using the slope analysis method, and the value of Kex for selenium(IV) extraction was found to be 26.17 ± 2 M− 2. The structure of the extracted organic species was confirmed by FT-IR. The effect of diluents using various aliphatic and aromatic diluents indicated that kerosene is the most preferred diluent. This is owing to safety ground purpose, economic consideration, the lower cost, availability, and lower toxicity. Thermodynamic parameters indicate the endothermic nature for the solvent extraction of selenium(IV) for the investigated system according to the positive value obtained of the enthalpy change (ΔH). Depending on the obtained results, the method was used to recover selenium(IV) from a simulated solution synthesized in hydrochloric acid medium, which is expected in anode slime leach liquor solution. [ABSTRACT FROM AUTHOR]

In this study, the cathode active material was first separated from the aluminum foil through a heat treatment at 500 °C. The separated cathode active material was calcined at a temperature of 1000 °C to remove completely carbon particles generated from the organic adhesive during heat treatment. Then, Co, Mn, and Ni were recovered from the cathode active material using lactic acid and oxalic acid as leaching and precipitating reagents. The lactic acid showed almost similar metal leaching effects from cathode active material compared to sulfuric acid, hydrochloric acid, and nitric acid. The optimal metal leaching efficiency by lactic acid was obtained when 30 g of the cathode active material was added to the 2 N lactic acid solution. At these conditions, the leaching efficiencies of Li, Mn, Co, and Ni were 90.4%, 89.2%, 92.2%, and 91.8%, respectively. Subsequently, when 5 g of oxalic acid was added to the lactic leachate of 2 N, a phenomenon in which all metals were precipitated was observed. Based on this result, the optimal condition for precipitating the leached metals using oxalic acid was oxalic acid/cathode active material = 1:7 (w/w %). Through XRD and EDX analysis, the precipitate was identified as a polynuclear crystalline material (NiCoMnC2O4·2H2O) in which the three components of Mn, Co, and Ni oxalates were mixed with approximately 7:4:10 in integer ratio of weight. The produced precipitate can be recycled as a raw material of cathode active material through simple heat treatment. [ABSTRACT FROM AUTHOR]

Following the Hunga Tonga–Hunga Ha'apai (HTHH) eruption in January 2022, significant reductions in stratospheric hydrochloric acid (HCl) were observed in the Southern Hemisphere mid‐latitudes during the latter half of 2022, suggesting potential chlorine activation. The objective of this study is to comprehensively understand the loss of HCl in the aftermath of HTHH. Satellite measurements and a global chemistry‐climate model are employed for the analysis. We find strong agreement of 2022 anomalies between the modeled and the measured data. The observed tracer‐tracer relations between nitrous oxide (N2O) and HCl indicate a significant role of chemical processing in the observed HCl reduction, especially during the austral winter of 2022. Further examining the roles of chlorine gas‐phase and heterogeneous chemistry, we find that heterogeneous chemistry emerges as the primary driver for the chemical loss of HCl, and the reaction between hypobromous acid (HOBr) and HCl on sulfate aerosols is the dominant loss process. Plain Language Summary: After the eruption of the Hunga Tonga–Hunga Ha'apai (HTHH) volcano in January 2022, there was a substantial decrease in stratospheric hydrochloric acid (HCl) in the Southern Hemisphere mid‐latitudes in the latter part of 2022. This decrease suggests that a chemical reaction involving chlorine processing might have happened. This study aims to comprehensively understand the significant loss of HCl following the HTHH eruption, utilizing satellite measurements and a global chemistry‐climate model for analysis. The anomalies in 2022 show remarkable agreement between the modeled and measured data. By comparing the levels of HCl with another gas called nitrous oxide (N2O), we discover that a lot of the HCl loss was due to chemical reactions, especially during the Southern Hemisphere winter. Upon further investigation into the role of chlorine gas‐phase and heterogeneous chemistry, heterogeneous chemistry emerges as a primary driver for the chemical loss of HCl. The reaction between hypobromous acid (HOBr) and HCl on sulfate aerosols is identified as the dominant loss process. Key Points: Analysis using both model and satellites suggest a significant role of chemical processing in the observed HCl reduction at 20 kmAnalysis of gas‐ and heterogeneous‐phase reactions indicates that heterogeneous chemistry is the main driver for the chemical loss of HClThe dominant heterogeneous loss for HCl is via HOBr + HCl, with HCl + OH also significant due to enhanced OH from heterogeneous chemistry [ABSTRACT FROM AUTHOR]

Enramycin, a common growth promoter utilized in chickens and pigs, is sensitive against Gram-positive bacteria, and the maximum residue limit (MRL) of enramycin set up by is 30 µg/kg. However, the methods have been reported for detecting enramycin have failed to meet the accuracy requirements, with the required limit of quantification being higher than the MRL. To address this issue, we developed a high-sensitive and robust analytical method based on ultrahigh-performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS), to determine enramycin residues in swine tissues, including liver, kidney, pork, and fat. The ENV cartridge was selected to cleanup and enrich analytes after being extracted using a mixture of 55% methanol containing 0.2 M hydrochloric acid. With comprehensively validation, this established method was found great linearity of enramycin in each tissue, with a coefficient of variation above 0.99. Satisfactory recoveries from four different spiking levels were acquired (70.99-101.40%) while the relative standard deviations were all below 9%. The limit of quantification of enramycin in the present study is 5 µg/kg in fat and 10 µg/kg in other tissues, meeting the requirements for conducting the corresponding safety evaluation study. This method was demonstrated with excellent specificity, stability, and high sensitivity. To conclude, this novel approach is sufficiently sensitive and robust for the safety evaluation of enramycin in food products. [ABSTRACT FROM AUTHOR]

Tailoring the properties of cellulose aerogel beads was investigated in the present study by using weak organic acids as coagulants. Three different weak acids were specifically chosen, acetic acid, lactic acid and citric acid. For comparative studies, a strong acid, hydrochloric acid was examined. The production of aerogel beads by conventional dropping technique was controlled and optimized for weak acids. Aerogels were characterized by density analyses, scanning electron microscopy, nitrogen adsorption–desorption analysis, X‐ray powder diffractometry and IR spectroscopy. In common, all the aerogel beads showed interconnected nanofibrillar network, high specific surface area, high pore volume, high porosity and meso‐ and macroporous structure. In particular, when the weakest acid (acetic acid) was used as coagulant in the regeneration bath, the lowest shrinkage was observed. As a result, the cellulose aerogel beads produced from acetic acid showed the highest values of specific surface area (423 m2 g−1) and pore volume (3.6 cm3 g−1). The porous structure can be tuned by the choice of regeneration bath, which has either strong acid or a high concentration of weak acid. The aerogel beads were pure and showed cellulose II crystallinity. Hence this study paves an alternative path way to tailor the properties of cellulose aerogel beads. [ABSTRACT FROM AUTHOR]

In this paper, the removal behavior of alkali and alkaline earth metals (AAEMs) and the evolution of microscopic characteristics in high alkali coal under the leaching of inorganic and organic acids are studied. The results show inorganic acids have better effect on the removal of AAEMs because of their stronger ability to convert carboxylate and phenol salts into covalent carboxylic acids and phenols. Citric acid has a slightly weaker effect than inorganic acids, and oxalic acid has the least effect. The improvement of slagging characteristics is consistent with the removal ability. Sulfuric acid, hydrochloric acid and citric acid are more effective in enhancing the calorific value of coal, with an enhancement of about 0.60 MJ/kg. After leaching, the pores and cracks in the coal are developed, and the mesopores have a tendency to shift to a lower pore size range. This trend is most pronounced in citric acid leached coal and hydrochloric acid leached coal. Sulfuric acid seriously damage the surface morphology, which results in a tendency of large pore transfer in S-form coal. [ABSTRACT FROM AUTHOR]

ABSTRACT Imidazole is one of the most important heterocyclic rings. This nucleus can be found in a plethora of substances in different knowledge areas such as medicinal, agrochemical, polymer, and dyestuff. N‐alkylation reactions involving N − 1 atom is a remarkable tool to synthesize many imidazole derivatives which can be attached to a great variety of functional groups. In this work, we synthesized 10 new intermediates 4‐chlorobutyl 1‐aryl‐1H‐pyrazole‐4‐carboxylates 3(a–j) from 1‐aryl‐1H‐pyrazole‐4‐carbonyl chlorides, obtained from 1‐aryl‐1H‐pyrazole‐4‐carboxylic acids 4(a–j), and 4‐chlorobutan‐1‐ol 1, generated by THF ring‐opening promoted by hydrochloric acid. Compounds 3(a–j) promoted N‐alkylation of 4(5)‐nitro‐1H‐imidazole to afford the targets 4‐(4‐nitro‐1H‐imidazol‐1‐yl)butyl 1‐aryl‐1H‐pyrazole‐4‐carboxylates 2(a–j) in 18%–85% yields. [ABSTRACT FROM AUTHOR]

Flexible Zn2+ ion hybrid capacitors (ZHCs) will play a crucial role in developing next‐generation wearable products, which demand portability, durability, and environmental adaptability. To further meet these requirements, Ti3C2Tx MXene with exceptional conductivity and robust mechanical properties can be utilized as cathodes, except for challenges such as the dense stacking of Ti3C2Tx nanosheets. In this study, a novel MXene cathode architecture has been developed with the facilitation of an ice template, which creates longitudinally aligned Ti3C2Tx arrays with microchannels. The introduction of hydrochloric acid to the Ti3C2Tx slurry induces a crumpled morphology, increasing active sites and enhancing ion transport with expanded interlayer spacing. Interestingly, experimental results and COMSOL simulations verify that the cathode structure also has effective impacts on the Zn anode with a weakened ion concentration gradient and suppressed dendrite formation. Consequently, the ZHCs exhibit enhanced electrochemical performance with excellent rate performance and long‐term cycling stability (enduring over 50 000 cycles at 5 A g−1) and further deliver a reliable low‐temperature operation by applying an anti‐freezing electrolyte. Moreover, flexible ZHCs assembled with gel electrolytes demonstrate excellent flexibility, improved rate performance, and mechanical stability, making them well‐suited for flexible electronics that power flexible LED panels. [ABSTRACT FROM AUTHOR]

2D transition metal borides (MBenes) with abundant surface terminals hold great promise in molecular sensing applications. However, MBenes from etching with fluorine‐containing reagents present inert ‐fluorine groups on the surface, which hinders their sensing capability. Herein, the multilayer fluorine‐free MoBTx MBene (where Tx represents O, OH, and Cl) with hydrophilic structure is prepared by a hydrothermal‐assisted hydrochloric acid etching strategy based on guidance from the first‐principle calculations. Significantly, the fluorine‐free MoBTx‐based humidity sensor is fabricated and demonstrates low resistance and excellent humidity performance, achieving a response of 90% to 98%RH and a high resolution of 1%RH at room temperature. By combining the experimental results with the first‐principles calculations, the interactions between MoBTx and H2O, including the adsorption and intercalation of H2O, are understood first in depth. Finally, the portable humidity early warning system for real‐time monitoring and early warning of infant enuresis and back sweating illustrates its potential for humidity sensing applications. This work not only provides guidance for preparation of fluorine‐free MBenes, but also contributes to advancing their exploration in sensing applications. [ABSTRACT FROM AUTHOR]

Brass is among the utility metals for daily life. We present an easy corrosion experiment for demonstration in high school or first-year undergraduate studies. Almost any kind of brass can be dezincified in 1 m hydrochloric acid. Copper as the noble component remains as salmon pink coating on the workpiece while zinc and lead, the latter being a frequent minor alloying component of brass, are dissolved. Lead can be detected as PbS (in-situ generation of H2S from a splinter of FeS or as PbI2 using KI). Zinc can be analyzed as Rinmann's green or via a microchemical drop reaction with dithizone. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of steel corrosion inhibitors based on poly(alkyl-phenyl)-2-imidazolines was synthesized from available reagents. Electronic parameters that influence binding to a metal surface have been determined, and the influence of substituents on the geometry of binding to the surface has been studied. The resulting compounds have a degree of protection of steel in hydrochloric acid solutions in individual form above 98% at 60 °C and in a mixture with urotropine more than 99% at 95 °C. [ABSTRACT FROM AUTHOR]

Objective: To prepare acetazolamide extended-release pellets by extrusion-spheronization process and assess its release behavior in vitro. Methods: Ion exchange chromatography was applied to determine the content of sodium lauryl sulfate as the functional excipient in the formulation of the reference listed drug. According to the formulation analysis of the reference listed drug, the water-insoluble microcrystalline cellulose was used as the matrix material of extended-release pellets, and the hydroxy propyl cellulose aqueous solution was used as the adhesive excipient. Through extrusion-spheronization process, the pellets became dense spheroids, so as to slowly release the drug. When viscosity of damp mass and release curves of capsules were considered as the main indexes, acetazolamide extended-release pellets were prepared by extrusion-spheronization process, dried and filled into capsules. The release curves of the self-made preparation and the reference drug in pH1.2 hydrochloric acid solution, pH 4.5 acetate buffer, pH 6.8 phosphate buffer and water were determined respectively. And the similarity factor (f) method was used to compare the similarity of the release curves between two formulations. Results: The types and amounts of excipients of the self-made preparation and the reference listed drug are basically the same. The preparation process of the pellets is relatively simple. And drugs can be released slowly from the self-made preparation in four different media. The release curve trends of the self-made preparation and the reference listed drug in four different media were basically similar, and the similarity factor (f) values of the release curve between two formulations were all above 50. Conclusion: The release behavior in vitro of the self-made preparation was consistent with that of the reference listed drug. [ABSTRACT FROM AUTHOR]

This article is devoted to the development of methods for obtaining raw materials and coagulants based on Auminzatau kaolin at the Zarkuduk site and the treatment of highly coloured wastewater from the production of paper from rice and wheat straw. The yield of kaolin, treated with a 30 % hydrochloric acid solution at an optimum calcination temperature of 500°C for 90 min, was 97.5 %. The optimum temperature for the interaction of hydrochloric acid is 25 - 30°C for 30 - 45 min. The efficiency of the coagulant application is 97.5 %. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru) is an important platinum group metal for the manufacture of advanced materials owing to its chemical and physical properties. Generally, it is extremely difficult to dissolve Ru metal by using acidic solutions containing strong oxidizing agents. Therefore, pretreatments like alkali fusion roasting at high temperature are practiced to render the Ru metal soluble in aqueous solution. In this work, a simple procedure was proposed to dissolve Ru metal at room temperature without any pretreatments. The dissolution procedure consisted of two steps: (i) oxidation of Ru metal to RuO4– by using pure NaClO solution; (ii) reduction of RuO4– to stable Ru2OCl104– by using HCl as a reducing agent. The role of NaClO and HCl in the dissolution of Ru metal was discussed on the basis of the potential-pH diagram and the corresponding oxidation and reduction reactions. The effect of several parameters like the concentration of NaClO and HCl, temperature, time, and pulp density was investigated. Optimum conditions were obtained to completely dissolve Ru metal by using NaClO and HCl solution without alkali fusion. [ABSTRACT FROM AUTHOR]

Copyright of Silicone Material is the property of Silicone Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Condensate blockage significantly impairs gas production in low-permeability reservoirs by reducing gas relative permeability and increasing condensate saturation near the wellbore. Particularly acute in reservoirs with low pressure and permeability, effective solutions are required to mitigate this formation damage. This study introduces a novel acid treatment strategy aimed at enhancing the injectivity index in gas reservoirs afflicted by condensate blockage. Leveraging mineralogical analysis, Hydrochloric Acid (HCl) was identified as the optimal acidizing agent. The most effective concentrations of HCl for rock dissolution—15% and 7.5%—were determined through dissolution tests. The research further advances by adding methanol to the acid mix, resulting in three distinct formulations: HCl 15 wt%, HCl 15 wt% + methanol, and HCl 7.5 wt% + methanol. Comprehensive wettability alteration tests and coreflood experiments were conducted to evaluate the efficacy of these systems in permeability enhancement. The HCl 7.5 wt% + methanol formulation demonstrated superior performance in permeability improvement and condensate blockage reduction, outshining the other systems. Notably, this new acid system effectively altered wettability from hydrophobic to hydrophilic, facilitating the passage of condensate through the pore throats and thus aiding in the removal of blockages. The integration of methanol with HCl, particularly at a 7.5 wt% concentration, represents a significant advancement in the treatment of condensate blockage in gas reservoirs, promising to improve gas recovery rates by addressing the challenges posed by low-permeability formations. [ABSTRACT FROM AUTHOR]

Matrix acidizing is a widely used technique in carbonate formations to improve production and injection rates by restoring or improving permeability. This study evaluates the stimulation efficacy of organic and inorganic acid combinations in the Sarajeh carbonate formation, with a focus on improving permeability within this potential tight gas formation. Through solubility and continuous flow tests, a mixture of HCl 7.5% + HAc 2.5% was found to significantly outperform the traditional HCl 15% solution. The HCl 7.5% + HAc 2.5% mixture had a solubility rate of 59.27% and improved permeability by 4.4 times compared to HCl 15%, indicating a higher dissolving capacity. The results of continuous flow tests showed that the mixed acid had the best pore volume to breakthrough (PVBt) value of 2.574 at a controlled injection rate of 2 cc/min. This study demonstrates the superior performance of a lower concentration HCl‐HAc acid formulation in matrix acidizing carbonate formations and confirms its potential as a more effective alternative to high concentration HCl treatments for the Sarajeh reservoir. [ABSTRACT FROM AUTHOR]

Abstract The increasing demand for corrosion prevention strategies that are both effective and sustainable is part of the research the background. Nonionic surfactants offer a potential replacement for traditional corrosion inhibitors. These surfactants are well-known for their low toxicity and biodegradability. The research involved conducting experimental tests (such as weight loss, polarization and impedance spectroscopy) and theoretical computations to investigate the role of nonionic surfactant (polyoxyethylene (7) tribenzyl phenyl ether) (PETPE) in controlling the corrosion of mild steel in hydrochloric acid (1.0 M HCl) environment. The results of the study demonstrated that PETPE exhibited significant corrosion inhibition properties for mild steel in HCl solution. The inhibition efficiency of PETPE was found to increase with increasing PETPE concentration. PETPE is an excellent corrosion inhibitor because it significantly reduces the rate of corrosion, as seen by the notable inhibition efficiency result (95.4%) at a relatively low dose of PETPE (100 ppm). Thermodynamic studies were used to discuss the fundamental mechanisms that control PETPE-acid interactions. The adsorption process followed Langmuir adsorption isotherm, indicating a monolayer adsorption of the PETPE on the mild surface. Theoretical computations confirm the strong inhibition behavior of PETPE. The innovative feature of this research is its comprehensive strategy, which integrates experimental studies and theoretical simulations to evaluate the impact of PETPE on the corrosion control of mild steel in hydrochloric acid. The combined effort has the ability to supply valuable knowledge into the mechanisms of corrosion that will lead to the establishment of powerful corrosion control strategies.

Abstract Solvent extraction of selenium(IV) ions from highly concentrated hydrochloric acid using 0.4 mol/L Aliquat 336 dissolved in kerosene was investigated. As a modifying agent, 1-octanol (10% v/v) was added to the organic phase to avoid the third phase formation. The effect of different parameters affecting the liquid-liquid extraction of selenium(IV) such as the acid concentration, shaking time, metal ion concentration in the aqueous phase, loading capacity, diluents, and temperature, was studied. The results indicate that selenium(IV) is extracted efficiently by 0.4 mol/L Aliquat 336 dissolved in kerosene. It was noticed that the extraction increased with the increase in the acid and Aliquat 336 concentrations, reaching an extraction percentage of about 92% at 8 mol/L HCl and 97.1% at 1 mol/L extractant. The extracted organic species is postulated to be [H2SeO2Cl2.2R4NCl]org by using the slope analysis method, and the value of Kex for selenium(IV) extraction was found to be 26.17 ± 2 M− 2. The structure of the extracted organic species was confirmed by FT-IR. The effect of diluents using various aliphatic and aromatic diluents indicated that kerosene is the most preferred diluent. This is owing to safety ground purpose, economic consideration, the lower cost, availability, and lower toxicity. Thermodynamic parameters indicate the endothermic nature for the solvent extraction of selenium(IV) for the investigated system according to the positive value obtained of the enthalpy change (ΔH). Depending on the obtained results, the method was used to recover selenium(IV) from a simulated solution synthesized in hydrochloric acid medium, which is expected in anode slime leach liquor solution.

Nickel-base alloy is a type of metal material with excellent properties and is widely used in many fields. However, in the harsh environment of the acid solution, corrosion causes the reduction of the service life of the alloys, thereby limiting the alloys' use and development. In this paper, the effect of Chromium (Cr) content on the microstructure and corrosion behavior of nickel-based alloys in hydrochloric acid (HCl) was studied by scanning electron microscopy (SEM), energy dispersive spectrum (EDS), electron backscatter diffraction (EBSD) and electrochemical workstation. Meanwhile, X-ray photoelectron spectroscopy (XPS) was used to investigate the composition and properties of the surface passive films. For the Cr20 and Cr30 alloys with a single face-centered cubic (FCC) structure, the Cr2O3 content in the passive films increased with the Cr content, effectively improving the corrosion resistance. As the Cr content continued to increase, the second phases having a body-centered cubic (BCC) lattice were precipitated both in the Cr40 and Cr50 samples, inducing microgalvanic corrosion, thus deteriorating the corrosion resistance. XPS results showed that, in the Cr30 alloy, the relative content of Cr2O3 and the bound water were the highest, indicating that its passive film had the best corrosion resistance. For the passive film, the pitting resistance was related to Cr content, appropriate Cr content improved the corrosion resistance.

Background: White spot lesions represent the first stage of caries and their prevalence has been increasing in recent years, particularly in patients undergoing orthodontic treatment. DIferential diagnosis and lesion activity are essential to decide on the clinical approaches to treatment. The aim of this study is to understand if the new diagnostic tools such as fluorescence, microradiography and computed microtomography have the potential to change the conventional treatment of white spots". Methods: A systematic search of available studies in the literature was carried out, using PRISMA guidelines, in Pubmed and Scopus electronic databases and manually to identify relevant articles to answer the PICO question: "Do the new diagnostic tools have the potential to change the conventional treatment of white spots?". This systematic review included randomized controlled trials (RCT), cross-sectional and longitudinal studies complying with the following inclusion criteria: (i) studies in humans, (ii) studies about white spot lesions, (iii) studies published between 2012 and 2023, (iv) studies having both diagnosis and treatment and (v) studies with full text available. In this review we excluded other systematic reviews of clinical trials and in vitro studies. The RoB tool was used to assess the risk of bias. Results: The systematic literature search identified 143 potentially relevant references, which after applying the exclusion criteria, resulted in 20 articles. Regarding diagnostic methods, most articles found were based on conventional methods of visual examination (n:10) or fluorescence (n:7). The least referenced diagnostic techniques were based on the use of clinical photographs (n:2), cross-sectional microradiography (n:1) and computed microtomography (n:1). The use of DIAGNOdent was reported by 3 in vitro studies. With regard to therapies, most studies reported the use of infiltrating resin (n:7) and fluoride-based products (n:5). Other studies have reported the use of self-assembling peptide P11-4 (n:1), home care (n:1), casein phosphopeptide-amorphous calcium phosphate (n:2) and hydrochloric acid (n:1). Combination therapies were also considered. Conclusion: Diagnostic tool does not have the potential to change the form of treatment, whether it is a conventional method or a more differentiated one. [ABSTRACT FROM AUTHOR]

Minerals containing TiO2 are common in Indonesia, such as ilmenite in iron sand deposits scattered along the country's coasts. Ilmenite is an important source of titanium. One method for making TiO2 from ilmenite is by solubilizing both the Fe and Ti elements in HCl and then immediately hydrolyze the Ti. The leaching of low-grade ilmenite (ground to 0.177-0.149 mm) is studied kinetically by HCl in a stirred reactor. The research was conducted using the caustic fusion method followed by HCl leaching. The leaching reaction kinetics at the optimum conditions are analyzed using response surface methodology (RSM) with a second-order polynomial equation model and SSE with the shrinking core model (SCM). The results showed that HCl concentration and leaching time were directly proportional to the leached titanium concentration. In contrast, the leaching temperature was inversely proportional. The optimum operating conditions were obtained at a temperature of 30 °C, 9 M HCl, and 120 min of leaching time. The shrinking core model is a better representation of the kinetics than RSM with a second-order polynomial equation model. Based on SCM, the rate of the leaching reaction of titanium from low-grade ilmenite is controlled by diffusion through the ash layer.

Sulfur nanoparticles (SNPs) have been successfully synthesized by applying Vachelia nilotica seed extract as a bioactive aqueous material by a disproportionation reaction of sodium thiosulfate pentahydrate (Na2S2O3.5H2O) with a 10% hydrochloric acid (HCl) at room temperature. The synthesized SNPs were characterized by UV–Visible, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction (XRD) techniques. The usual size of SNPs was determined by an XRD study and calculated with the Debye–Scherrer formula. The SNPs are crystalline with a calculated average size of 45 nm. The SEM and TEM analyses revealed spherical shape and size around 55 nm of SNPs. The synthesized SNPs were screened for their antifungal activity against M. furfur species and for anticancer activities against (MCF-7, HepG2) cell lines. The obtained results suggested towards moderate to good antifungal and excellent anticancer activities. [ABSTRACT FROM AUTHOR]

A convenient, fast, selective, sustainable detection and capture of hydrochloric acid and ammonia vapours in the solid state with bare eye colour switching is observed by a robust microporous 2D zigzag Zn-MOF based material. Here ESIPT off/on based dual emission alteration has been employed for sensing. [ABSTRACT FROM AUTHOR]

Solvent extraction of lithium from brine with a high Mg/Li ratio was investigated. Tributyl phosphate (TBP), ferric chloride (FeCl3), and kerosene were used as the extractant, co-extractant, and diluent, respectively. The mechanism of the extraction process was studied by LC–MS, UV–VIS, and FT-IR analyses. Effects of organic to aqueous phase volume ratio (O/A) on the extraction efficiency and separation factor were optimized. The effects of major parameters including Fe/Li molar ratio, hydrochloric acid concentration, and TBP volume percent as well as their interactions on the lithium extraction efficiency were evaluated using central composite design. These major parameters represent interactions within their selected ranges. While the lithium extraction efficiency as the response value in the experimental design showed the most sensitivity to the acid concentration, the separation factors were more affected by alteration in the TBP volume percent with the fixed optimum values of the other major parameters. The highest one-stage extraction efficiency of 76.3% and Li/Mg separation factor of 304 were obtained at the optimum conditions of Fe/Li = 2.99, HCl = 0.01 M, and TBP = 55%. The Mg/Li mass ratio could be significantly reduced from 192 in the feed to 1.5 in the stripping solution. Based on the findings, a schematic diagram of the process including extraction, stripping, and saponification steps was proposed. [ABSTRACT FROM AUTHOR]

A continuous flow metal‐free protocol for the synthesis of sulfonyl chlorides from thiols and disulfides in the presence of nitric acid, hydrochloric acid and oxygen was developed. The influence of the reaction parameters was investigated under batch and flow conditions. Online 19F NMR was successfully implemented to investigate different reaction conditions within a single experiment. The sulfonyl chlorides were isolated (mostly in 70–81 % yield) after performing a simple aqueous washing procedure. In particular, the protocol was successfully operated for >6 hours to convert diphenyl disulfide to its corresponding sulfonyl chloride, achieving a throughput of 3.7 g h−1. The environmental impact of the protocol was assessed and compared to an existing continuous flow protocol using 1,3‐dichloro‐5,5‐dimethylhydantoin (DCH) as reagent. The process mass intensity (PMI) for the newly‐developed flow protocol (15) compared favorably to the DCH flow process (20). [ABSTRACT FROM AUTHOR]

This Tutorial Review acquaints chemists and metallurgists with the properties and industrial applications of methanesulfonic acid (MSA, CH3SO3H). Over the past quarter-century, MSA has garnered increasing interest as a reagent for green chemistry due to its strong acidity, while circumventing many of the challenges associated with handling concentrated sulfuric acid, hydrochloric acid, or nitric acid. Concentrated MSA is a non-oxidizing reagent, exhibiting high chemical stability against redox reactions and hydrolysis, as well as high thermal stability and limited corrosivity towards construction materials. It is colorless, odorless, and possesses a very low vapor pressure. MSA combines commendable biodegradability with low toxicity. It is extensively utilized as a Brønsted acid catalyst for esterification or alkylation reactions, and is employed in biodiesel production. The high solubility of its metal salts, the high electrical conductivity of its concentrated solutions, coupled with the high electrochemical stability of MSA and its anion, make MSA-based electrolytes beneficial in electrochemical applications. Examples include the electrodeposition of tin–lead solder for electronic applications and the high-speed plating of tin on steel plate for food cans. MSA-based electrolytes are used in redox flow batteries (RFBs). MSA offers a much safer and environmentally friendlier alternative to electrolytes based on fluoroboric or fluorosilicic acid. A novel application area is as a strong acid in extractive metallurgy, where it may contribute to the development of circular hydrometallurgy. MSA is being explored in lithium-ion battery recycling flowsheets, as well as in other applications in the field of metal recovery and refining. However, this review is not solely about the advantages of MSA for green chemistry or clean technologies, as there are also some potential drawbacks. Apart from its higher price compared to regular strong acids, MSA has only minor advantages for applications where sulfuric acid performs well. Since methanesulfonate biodegrades into sulfate, the same emission restrictions as for sulfate should be considered. In conclusion, MSA is the acid of choice for applications where metal sulfates cannot be used due to poor solubility or where concentrated sulfuric acid is too reactive towards organics. [ABSTRACT FROM AUTHOR]

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems. [ABSTRACT FROM AUTHOR]