Corrosive Acid Research Articles

Photocatalytic Anaerobic Dehydrogenation of Alcohols over Metal Halide Perovskites: A New Acid-Free Scheme for H2 Production.

Photocatalytic H2 evolution from haloid acid (HX) solution by metal halide perovskites (MHPs) has been intensively investigated; however, the corrosive acid solution severely restricts its practical operability. Therefore, developing acid-free schemes for H2 evolution using MHPs is highly desired. Here, we investigate the photocatalytic anaerobic dehydrogenation of alcohols over a series of MHPs (APbX3, A = Cs+, CH3NH3+ (MA), CH(NH2)2+ (FA); X = Cl-, Br-, I-) to simultaneously produce H2 and aldehydes. Via the coassembly of Pt and rGO nanosheets on MAPbBr3 microcrystals, the optimal MAPbBr3/rGO-Pt reaches a H2 evolution rate of 3150 μmol g-1 h-1 under visible light irradiation (780 nm ≥ λ ≥ 400 nm), which is more than 105-fold higher than pure MAPbBr3 (30 μmol g-1 h-1). The present work not only brings new ample opportunities toward photocatalytic H2 evolution but also opens up new avenues for more effective utilization of MHPs in photocatalysis.

Acid-free fabrication of polyaryletherketone membranes

Polyaryletherketones (PAEKs) are a class of ultrahigh performance polymers with outstanding temperature and chemical resistance. Poly(ether ketone ketone) copolymer (Kepstan®) and poly(ether ether ketone) (PEEK) display intrinsic insolubility in nearly all organic solvents. The primary issue for the application of these polymers is their processability which requires a high temperature/pressure-based technique, or the use of harsh and corrosive solvents, like methanesulfonic and sulfuric acid, resulting in sulfonation of the polymer backbone that adversely might affect their chemical stability. In this work, we propose a method to prepare porous Kepstan® and PEEK membranes using N-methyl-2-pyrrolidone (NMP) as solvent at room temperature. It consisted of a modification-regeneration strategy to turn commercial semi-crystalline Kepstan® and PEEK into dithiolane soluble derivatives that allow the fabrication of hollow fiber, flat-sheet, and electrospun nanofibers. The resulting membranes are then regenerated to the solvent-resistant materials. The novel Kepstan® and PEEK hollow fibers exhibited a N,N-dimethylformamide (DMF) permeance of 2.21 and 2.05 L m−2 h−2 bar−1, with more than 90% rejection of Crystal Violet (408 g mol−1) and Methyl Orange (327 g mol−1), respectively.

Sulfonic acid-functionalized silica with controlled hydrophobicity as an effective catalyst for esterification of levulinic acid

As one of the essential additives in biodiesel and flavoring agents, solvents, and plasticizers in industry, ethyl levulinate (EL) has gained attention in the last two decades, and the global production of the compound is rapidly increased over the years. So far, esterification of biomass-derived levulinic acid (LA) with ethanol (EtOH) in the presence of highly corrosive mineral acid catalysts is the most common technique for the reaction. To avoid the harsh environment during the reaction and to ease the separation of the catalyst, the research has been recently focused on developing highly active solid acid catalysts. In this research, we have systematically investigated the catalytic activity of sulfonic acid-functionalized silica (SiO2-SO3H) with different hydrophobicity for esterification of LA with EtOH. The hydrophobicity of SiO2-SO3H was tuned by incorporating three different alkylsilanes, e.g., methyl (Me), octyl (Oct), and hexadecyl (HD) silanes on the surface of the material. We found that the longer the alkyl group, the lower the acidity and thus resulted in the lower the catalytic activity. On the other hand, the particle size and hydrophobicity increase with the length in the alkyl group. SiO2-SO3H modified with the methyl group (SiO2-SO3H/Me) showed the highest acidity (0.76 mmol g–1) and the highest catalytic performance (70.6% conversion). Moreover, while all alkyl-modified catalysts followed pseudo-first-order, the pseudo-first-order rate constant (k1p) for the reaction over SiO2-SO3H/Me was 5.4 × 10–3 min–1. The kinetic results of this study could be useful for reactor modeling and simulation in the future.

A Weak Acidic and Strong Coordinated Deep Eutectic Solvent for Recycling of Cathode from Spent Lithium-Ion Batteries.

The leaching and recycling of valuable metals via environmentally benign solvents is important because of the ever-increasing waste lithium-ion batteries, but it remains a challenge. Herein, a multi-functional deep eutectic solvent (DES) based on lactic acid (LA) and guanidine hydrochloride (GHC) was used to extract cobalt and lithium ions from LiCoO2 . Due to the strong acidity (protons) and abundant chlorine coordinating ions of LA/GHC, the solubility of LiCoO2 in LA/GHC could reach as high as 19.9 mg g-1 (stirred at 80 °C for 24 h), and a little LiCoO2 powder even could be dissolved at room temperature without stirring. Oxalic acid was used to strip and separate the oxalates of cobalt and lithium. Furthermore, LA/GHC could be recycled with a similar dissolving performance. This work avoided using corrosive acids and could be realized at low temperature (80 °C), making it energy-saving and cost-effective. It shows DESs have great potential in extracting strategically important metals from LiCoO2 cathodes and provides an efficient and green alternative for sustainable recycling of spent lithium-ion batteries.

국내 중독 및 화학사고에서 불소화합물의 유형 분석 : 감정사례 기반 사고대비물질

Fluoride compounds through ingestion, inhalation or skin contact hydrolyze to fluoride ion and form corrosive hydrofluoric acid on the mucosa, and also act as a direct cellular poison which interferes with calcium metabolism and enzyme mechanisms to induce hyperkalemia and hypocalcemia, following to dysrhythmias and cardiac arrest. Although fluoride compound is very important substance in forensic science, it is one of the substances that are difficult to be identified by a routine toxicological analysis among all chemicals in the forensic case caused by "unknown" substance or a workplace chemical accident. Identification of fluoride compound often goes beyond the general analytical procedure, so a more systematic procedure should be suggested. This study reviews the analytical results of fluoride compound-related accident cases submitted to the National Forensic Service and presents improved analytical plans. In the case reviewed, hydrogen fluoride, sodium fluoride, ammonium fluoride, sodium fluorosilicate, calcium fluoride, nitrogen trifluoride were identified. These six types of fluoride compounds are suggested as accident preparedness substances that should be considered in forensic analysis of hazardous chemical accident in Korea.

A facile, green fabrication of aqueous nanofluids containing hydrophilic functionalized carbon nanotubes toward improving heat transfer in a closed horizontal flow passage

In the present research, the synthesis of highly stable multiwalled carbon nanotubes in aqueous media is developed using a one-pot, covalent and green functionalization technique to improve the heat transfer and hydrodynamic behavior of a horizontal stainless-steel tube subjected to a uniform heat flow at its outer surface. Instead of using corrosive inorganic acids, the free radical grafting of gallic acids is used in this procedure. In this work, GA-functionalized multiwalled carbon nanotubes water-based colloidal suspensions (nanofluids) were prepared at three different weight concentrations. Various characterization techniques comprising Fourier transform infrared spectroscopy, Raman spectroscopy, High resolution transmission Electron Microscopy, and zeta-potential measurements were performed and confirmed the success of MWCNT functionalization. The thermophysical properties were evaluated experimentally and validated using empirical correlations available in the literature. To prove the colloidal suspension stability, ultraviolet-visible spectroscopy was used, and the results showed that nanofluid was stable for almost 60 days. When the GAMWCNT concentration was increased, there was a significant improvement in the thermal conductivity. Moreover, the nanofluids' dynamic viscosity experienced a slight increment up to 7.30% when the GAMWCNTs were loaded relative to distilled water. Following the confirmation of the experimental setup's analytical correlations, tests for the colloidal GAMWCNT suspension flowing through a heated horizontal tube were carried out in a fully developed turbulent state. A significant enhancement in the convective heat transfer coefficient was obtained, with only minor growth in the relative pumping power by 33.05 and 1.19%, respectively. More importantly, the reported positive performance index indicator for all the Reynolds numbers of ranges shows the possibility of using the synthesized GAMWCNT aqueous suspensions as an alternative working fluid in heat transfer systems.

Continuous flow process for preparing budesonide.

Budesonide, a glucocorticosteroid, is used as anti-asthmatic drug that became generic in 2019. Existing preparation methods of budesonide require utilization of corrosive acids and involve expensive purification process. Thus, a new cost-effective continuous flow process for the synthesis of budesonide which belongs to the class of 16,17 acetals of pregnane core, is discussed in the present research findings. Flow reactor parameters such as flow rate, temperature, residence time, solution volumes, anti-solvents and reactor frequency are subjected to investigation on the preparation of molar ratio of budesonide epimers. Further, the suitable parameters entail for obtaining the desired molar ratio of epimers. In another aspect, particle size optimization studies are also performed to get the desired budesonide solid product. A continuous flow process for preparation of budesonide is identified from the present research investigation which can be readily transferred to industrial scale up.Graphical abstract

The interaction between rainwater and polished building stones for flooring and cladding - Implications in architecture

Stone polishing is a process executed to make the surface glossy, so that the material shines by reflecting the light. The polishing is mainly carried out in flooring and façade cladding to improve the aesthetic properties of the stones. In particular on calcareous stones, polishing is not a permanent feature because various atmospheric agents in outdoor (e.g. rain, freeze and thawing cycles, UV solar radiation) are responsible for weathering with the loss of the mirror-like effect.In this paper, the effects of rainwater on polished limestones used for building cladding have been shown.In order to better reproduce the environmental conditions in building location, two samples horizontally and vertically oriented (simulating flooring and façade cladding respectively), were subjected to rainwater wetting. Other two samples with the same previous orientations were subjected to tap water wetting. After a month test it has been demonstrated how rainwater, differently to tap water, causes micro-corrosion on the samples surface by a modification of the colour and a decreasing of the gloss. This is attributable to a roughness increase. The corrosion intensity depends on the orientation of the samples. The reason of this corrosion is the capacity of the rainwater (with a low saline content) to easily dissolve air carbon dioxide by forming corrosive carbonic acid with respect to high saline content tap water.

A rare case of corrosive acid ingestion-induced distorted airway.

A rare case of corrosive acid ingestion-induced distorted airway.

One-Step Synthesis of Iron and Titanium-Based Compounds Using Black Mineral Sands and Oxalic Acid under Subcritical Water Conditions

Black mineral sands are widely used to obtain titanium dioxide, titanium, and, more recently, a variety of iron–titanium oxide nanostructures. Highly corrosive mineral acids or alkalis are commonly employed for this purpose. Hence, it is desirable to find eco-friendly ways to process these minerals, deriving high-added value materials. In this study, an Ecuadorian mineral sand precursor (0.6FeTiO3∙0.4Fe2O3 solid solution) was treated with oxalic acid aqueous solutions under subcritical water conditions. The synthesis was conducted in a batch reactor operating at 155 °C, 50 bar, and 700 rpm for 12 h, varying the oxalic acid concentration (0.1, 0.5 to 1.0 M). The as-obtained compounds were physically separated, dried, and analyzed by X-ray powder diffraction, scanning electron microscopy, and Raman spectroscopy. The characterization showed that the precursor was completely converted into two main products, ferrous oxalate, and titanium dioxide polymorphs. Rutile was always found in the as-synthesized products, while anatase only crystallized with high oxalic acid concentrations (0.5 and 1.0 M). These results open the possibility to develop more sustainable routes to synthesize iron and titanium-based materials with promising applications.

Ppm-level Cu dopant on ultrathin Pd nanosheets/TiO2 for highly enhanced photocatalytic alcoholysis of epoxides

Photocatalysis provides a new avenue for organic synthesis, to which catalyst design at atomic level holds the key. Herein, the first case of ppm-level (39 ppm) Cu dopant based photocatalyst has been successfully constructed as Cu1Pd200/TiO2, in which Cu element dopes ultrathin Pd nanosheets (thickness of 2 nm) with atomic dispersion using TiO2 as the semiconductor host. The alcoholysis of styrene oxide, as a model reaction, can produce valuable β-alkoxy alcohols, conventionally requiring corrosive strong acids or harsh reaction conditions. The presence of ppm-level Cu atoms in Cu1Pd200/TiO2 can boost alcoholysis with a quite high reaction rate of 176 mmol·g−1·h−1 at room temperature under light illumination (100 mW·cm2), which is 6 times and 17 times higher than Pd/TiO2 and bare TiO2, respectively. Moreover, the Cu-doped photocatalyst presents excellent stability without deactivation after ten cycles. Based on X-ray photoelectron spectroscopy, infrared spectroscopy and control experiments, this unexpected photocatalytic behavior mainly origins from the electron transfer effect and unique chemisorption of epoxides owing to Cu dopant.

An Audit of more than a Thousand uppergastrointestinal Endoscopy in a Tertiary Care Teaching Hospital in South India

Background: Esophagogastroduodeno (EGD) scopy is a benchmark in the modern era of medicine. It is a sensitive tool used to evaluate the upper gastrointestinal (GI) symptoms. Application of EGDscopy is not merely restricted to diagnosis but as well used for therapeutic purpose. Aim of the Study: To find out the common indications for EGDscopy and its findings in a large tertiary care hospital attached to Bangalore medical college and research institute (BMCRI), Bengaluru. Materials and Methods: A retrospective study was conducted on 1030 patients either admitted or seen on outpatient basis at the Bowring and Lady Curzon hospital attached to BMCRI, Bengaluru with the upper GI symptoms like dyspepsia, dysphagia, epigastric pain abdomen, hematemesis etc from September 2016 to August 2018 and the data was analyzed using appropriate statistical methods. Results: Out of 1030 patients who underwent EGDscopy 62% were male and 61% were 31-59year old. The major indications for EGDscopy were epigastric abdominal pain (18%), dyspepsia (18%), chronic liver disease (15%), dysphagia (11%) and hematemesis (8%). The common pathological findings in the above mentioned indications were gastritis and esophagitis in patient with both epigastric abdominal pain and dyspepsia, portal hypertensive gastropathy and esophageal varices in chronic liver disease, esophageal growth in dysphagia and esophageal varices (EV) in cases of hematemesis. Conclusions: The following insights/observations were made during the course of our study-dysphagia is not just oropharyngeal or esophageal in origin but H. pylori gastritis can cause similar complaints, eradication of which relieves the symptoms in our observation. Chronic abdominal pain associated with postprandial urgency which is deemed as Inflammatory Bowel Disease-Diarrhea (IBS-D) may actually be H. pylori gastritis with exaggerated gastro-colic reflex which gets relieved with anti- H. pylori treatment; further studies are needed to prove this claim. Mosaic like pattern with focal areas of hyperemia in the gastric body mucosa is not just typical of portal hypertensive gastropathy but also can be seen with H. pylori gastritis. Corrosive acid ingestion as a mode of suicidal attempt is common in this part of India which can lead to morbidity and even mortality in severe cases, legislative measures need to be put in place to check the sale and use of corrosive acid. Diffuse white spots in duodenum were mostly due to chronic nonspecific duodenitis rather than intestinal lymphangiectasia in our study.

A mixed acid methodology to produce thermally stable cellulose nanocrystal at high yield using phosphoric acid

Cellulose nanocrystal (CNC) with distinctive shape-morphology, enhanced thermal stability and dispersibility is essential for overcoming the challenges in processing polymer/CNC nanocomposites through melt compounding at elevated temperatures. This study shows a mixed acid hydrolysis method to produce CNC with improved thermal stability and high productivity. The use of phosphoric acid (H3PO4), as a mild acid, in combination with a strong acid either sulphuric acid (H2SO4) or hydrochloric acid (HCl) leads to reduced use of strong acids and low impact on our environment. The influences of acid combination and sequence of addition on the production yield were investigated by retaining the proportion of H3PO4 to corrosive acid (H2SO4 and HCl) 4 to 1, and solid to liquid ratio 1꞉75. This methodology has enabled to isolate CNC with higher thermal stability, dispersibility and productivity in terms of amount acid used 1 g of CNC, as compared with single acid hydrolysis. The CNC produced using the combination of H3PO4 and HCl exhibits high thermal stability, dispersibility and rod-like shape morphology with length and width of (424 ± 86) and (22 ± 3) nm, respectively. Moreover, this approach has reduced H3PO4 consumption by 54% as compared with single acid hydrolysis method for the production of same amount of CNC.

The Impact of Thermal Desorption Unit Associated with Remediation of Hydrocarbon Impacted Soils on Air Quality at Beneku, Ndokwa East, Delta State, Nigeria

The study is on the use of thermal desorption unit in the remediation of contaminated soils located at Beneku in Ndokwa East local government area of Delta state. This method uses heat to vaporize the contaminants, and as such only works for volatile contaminants. Air quality samples around the thermal desorption Unit (TDU), used for the treatment of hydrocarbon impacted soils were taken at six (6) different sampling points (Stations). The sampling points were 100 m apart beginning from 0 m which was the closest to the TDU. The results showed that the mean values of SO2 were 0.01 ppm for both the dry and wet seasons and it is within the FMEnv limit of 0.01. The mean concentration of NO2 in the dry season was 0.25 μg/m3 and in the wet season it was 0.18 μg/m3, which were above the FMEnv limit of 0.06 μg/m3. It is a strong oxidizing agent that reacts with air/water to form corrosive nitric acid, as well as toxic organic nitrates. The mean concentration of CO2 recorded in the dry season was 11.52 ppm and that for the wet season was 10.53 ppm, which were slightly above the FMEnv limit of 10.00 ppm. The levels of SPM 2.5 recorded in the study show a concentration of 132.07 μg/m3 in the dry season and 95.93 μg/m3 in the wet season while those for SPM 10 had 102.17 μg/m3 in the dry season and 91.33 μg/m3 in the wet season. The level of the VOC recorded across the study area was significantly low (0.11 μg/m3). The mean H2S concentration recorded across the study area was low (0.01 μg/m3). Several health risks have been associated with SPM. Inhaling SPM affects respiratory and cardiovascular systems in both children and adults. Fine SPM (such as PM 2.5 particulate) can penetrate into the lungs and blood streams when inhaled, resulting to respiratory problems, heart attack, lung cancer and even death, while exposure to low levels of H2S can induce headaches as well as breathing difficulties in some asthmatic patients.

Resistance of the welded joint of austenitic steel NEUTRONIT A 976 SM in the corrosive environment of boric acid

Abstract The paper deals with the influence of the operating environment on the safe resistance of the welded joint of the construction material used in the nuclear power industry in the production of spent nuclear fuel containers. This material contains a higher percentage of alloying boron and is used as a shielding construction material for neutron and gamma radiation. It is used to produce baskets for spent nuclear fuel containers. When the containers are being filled, the welded joint of the basket structure are briefly exposed to an aqueous boric acid solution. The aim of this work was to determine the effects of exposure to the corrosive boric acid environment on the mechanical properties of the material. Tensile tests on the original weld and post weld exposure in H3BO3 and corrosion cracking tests on unexposed welds were performed. The evaluation of the results revealed that the exposure to the corrosive environment of boric acid did not significantly affect the strength characteristics of the tested material NEUTRONIT A 976 SM.

Delamination of polyimide in hydrofluoric acid

Wet etching is a critical fabrication step for the mass production of micro and nanoelectronic devices. However, when an extremely corrosive acid such as hydrofluoric (HF) acid are used during etching, an undesirable damage might occur if the device includes a material that is not compatible with the acid. Polyimide thin films can serve as sacrificial/structural layers to fabricate freestanding or flexible devices. The importance of polyimide in microelectronics is due to its relatively low stress and compatibility with standard micromachining processes. In this work, a fast delamination process of a 4-μm-thin film of polyimide from a silicon substrate has been demonstrated. The films’ detachment has been performed using a wet-based etchant of HF acid. Specifically, the effect of HF concentration on the delamination time required to detach the polyimide film from the substrate has been investigated. This study is intended to provide the information on the compatibility of using polyimide films with HF, which can help in the design and fabrication of polyimide-based devices.

A suicidal heavy metal poisoning mimicking corrosive acid poisoning: A rare case report

Ingestion of corrosive substances may cause severe to serious injuries of the upper aero-digestive tractand the poisoning can even result in death. Acute corrosive intoxications pose a major problem in clinical toxicology since the most commonly affected population are the young with psychic disorders, suicidal intent and alcohol addiction. In our case report, a 19-year-old male, 2year engineering student committed suicide by consuming a heavy metal salt available in his chemistry lab after leaving a suicidal note. He got treated in a private hospital for 2 days and later he succumbed due to poisoning. Though the findings of this heavy metal poisoning mimicks corrosive acid poisoning, it has to be viewed through the eye of forensic toxicology for a clear view in clinching the diagnosis in the earlier phase of treatment.

The inhibitory action of 3-phenyl-isoxazoline-carvone on carbon steel in HCl solution was investigated experimentally and theoretically

For carbon steel (CS) in a corrosive hydraulic acid solution, various quantities of the molecule 3-phenyl-isoxazoline-carvone (PIC) were employed (1M; HCL). The inhibitory effects of the 3-phenyl-isoxazoline-carvone (PIC) were evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), weight loss, surface morphology analysis (SEM), quantum chemical calculations (DFT), and Monte Carlo simulations (MC). According to the findings, the compound, 3-phenyl-isoxazoline-carvone (PIC) is a mixed-type inhibitor that significantly decreased the rate of carbon steel (CS) corrosion by creating a protective coating on the carbon steel surface (CS). According to EIS, PDP, and mass loss studies, the molecule 3-phenyl-isoxazoline-carvone (PIC) is a stronger corrosion inhibitor, with corrosion effectiveness of about 95% at 298 K temperature. Adsorption of the 3-phenyl-isoxazoline-carvone (PIC) molecule on the surface of carbon steel includes both physisorption and chemisorption, according to the Langmuir isotherm model. Aside from experimental methods, theoretical methods such as DFT simulations, molecular dynamics simulations, and the radial distribution method were used to provide detailed knowledge about the mechanism of corrosion inhibition and to reveal factors controlling the efficiency of the investigated inhibitor.

Enzymatic Synthesis of Alkyl Glucosides byβ‐Glucosidases in a 2‐in‐1 Deep Eutectic Solvent System

AbstractAlkyl glycosides are biodegradable surfactants with excellent physico‐chemical properties. Although their wide‐range application is considered ecofriendly, their synthesis is not due to the need for toxic organic solvents and corrosive acids as catalysts. Moreover, chemical synthesis results in complex mixtures rather than defined compounds. To overcome both disadvantages as well as the limited solubility of sugars in organic solvents, a highly selective enzymatic synthesis was set up with aβ‐glucosidase condensing D‐glucose and different fatty alcohols in a deep eutectic solvent.

Phase Control of Solid-Solution Nanoparticles beyond the Phase Diagram for Enhanced Catalytic Properties.

The crystal structure, which intrinsically affects the properties of solids, is determined by the constituent elements and composition of solids. Therefore, it cannot be easily controlled beyond the phase diagram because of thermodynamic limitations. Here, we demonstrate the first example of controlling the crystal structures of a solid-solution nanoparticle (NP) entirely without changing its composition and size. We synthesized face-centered cubic (fcc) or hexagonal close-packed (hcp) structured Pd x Ru1-x NPs (x = 0.4, 0.5, and 0.6), although they cannot be synthesized as bulk materials. Crystal-structure control greatly improves the catalytic properties; that is, the hcp-Pd x Ru1-x NPs exceed their fcc counterparts toward the oxygen evolution reaction (OER) in corrosive acid. These NPs only require an overpotential (η) of 200 mV at 10 mA cm-2, can maintain the activity for more than 20 h, greatly outperforming the fcc-Pd0.4Ru0.6 NPs (η = 280 mV, 9 min), and are among the most efficient OER catalysts reported. Synchrotron X-ray-based spectroscopy, atomic-resolution electron microscopy, and density functional theory (DFT) calculations suggest that the enhanced OER performance of hcp-PdRu originates from the high stability against oxidative dissolution.