HCl Aqueous Solution Research Articles

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans / Cis Isomers

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing <i>Trans</i> / <i>Cis</i> Isomers

Single‐Step Synthesis of Exfoliated Ti3C2Tx MXene through NaBF4/HCl Etching as Electrode Material for Asymmetric Supercapacitor

AbstractTwo‐dimensional Ti3C2Tx MXene, derived from the parent Ti3AlC2 phase, is considered a promising electrode material for electrochemical energy storage applications. Ti3C2Tx MXene synthesis methods often employ concentrated hydrofluoric acid (HF), which is harsh, corrosive, and hazardous to the environment. Herein, we report the preparation of Ti3C2Tx MXene following a new synthetic route under a mild reaction condition comprising an aqueous solution of NaBF4 and HCl. This etching environment at a moderate temperature of 130 °C effectively removes the Al layer of the Ti3AlC2 precursor, assisted by the in situ formed HF in the reaction medium. Electron microscopy images of the as‐prepared Ti3C2Tx (MX‐130) reveal a partially exfoliated nanosheet‐like morphology. The material displays a specific capacitance of 262 F g−1 (three‐electrode assembly, 1 A g−1, −0.85 to −0.25 V vs. Hg/Hg2SO4) in 1 M H2SO4 electrolyte. The achieved specific capacitance is superior to that of Ti3C2Tx prepared via the common HF‐treatment (25 F g−1). Additionally, the potential application of the optimized MXene as a negative electrode material is demonstrated in a quasi‐solid‐state RuO2|MX‐130 asymmetric supercapacitor device.

Use of Time Domain Nuclear Magnetic Resonance Relaxometry to Monitor the Effect of Magnetic Field on the Copper Corrosion Rate in Real Time

The corrosion of metals is a major problem of modern societies, demanding new technologies and studies to understand and minimize it. Here we evaluated the effect of a magnetic field (B) on the corrosion of copper in aqueous HCl solution under open circuit potential. The corrosion product, Cu2+, is a paramagnetic ion and its concentration in the solution was determined in real time in the corrosion cell by time-domain NMR relaxometry. The results show that the magnetic field (B = 0.23 T) of the time-domain NMR instrument reduces the corrosion rate by almost 50%, in comparison to when the corrosion reaction is performed in the absence of B. Atomic force microscopy and X-ray diffraction results of the analysis of the corroded surfaces reveal a detectable CuCl phase and an altered morphology when B is present. The protective effect of B was explained by magnetic forces that maintain the Cu2+ in the solution/metal interface for a longer time, hindering the arrival of the new corrosive agents, and leading to the formation of a CuCl phase, which may contribute to the rougher surface. The time-domain NMR method proved to be useful to study the effect of B in the corrosion of other metals or other corrosive liquid media when the reactions produce or consume paramagnetic ions.

Aminopolycarboxylic Acids-Functionalized Chitosan-Based Composite Cryogels as Valuable Heavy Metal Ions Sorbents: Fixed-Bed Column Studies and Theoretical Analysis.

Over the years, a large number of sorption experiments using the aminopolycarboxylic acid (APCA)-functionalized adsorbents were carried out in batch conditions, but prospective research should also be directed towards column studies to check their industrial/commercial feasibility. In this context, sorption studies of five-component heavy metal ion (HMI) solutions containing Zn2+, Pb2+, Cd2+, Ni2+, and Co2+ in equimolar concentrations were assessed in fixed-bed columns using some APCA-functionalized chitosan-clinoptilolite (CS-CPL) cryogel sorbents in comparison to unmodified composite materials. The overall sorption tendency of the APCA-functionalized composite sorbents followed the sequence Co2+ < Zn2+ < Cd2+ ≤ Pb2+ < Ni2+, meaning that Co2+ ions had the lowest affinity for the sorbent’s functional groups, whereas the Ni2+ ions were strongly and preferentially adsorbed. To get more insights into the application of the composite microbeads into continuous flow set-up, the kinetic data were described by Thomas and Yoon–Nelson models. A maximum theoretical HMI sorption capacity of 145.55 mg/g and a 50% breakthrough time of 121.5 min were estimated for the column containing CSEDTA-CPL cryogel sorbents; both values were much higher than those obtained for the column filled with pristine CS-CPL sorbents. In addition, desorption of HMIs from the composite microbeads in dynamic conditions was successfully achieved using 0.1 M HCl aqueous solution. Moreover, a theoretical analysis of APCA structures attached to composite adsorbents and their spatial structures within the complex combinations with transition metals was systematically performed. Starting from the most stable conformer of EDTA, coordinative combinations with HMIs can be obtained with an energy consumption of only 1 kcal/mole, which is enough to shift the spatial structure into a favorable conformation for HMI chelation.

Electro-Osmotic Flow of Water–Methanol Mixtures Through Nafion Membranes Revisited: Composition and Temperature Dependence

The electro-osmotic drag coefficient of water and methanol mixtures through Nafion 117 membranes was measured as a function of the composition at several temperatures between 25 and 60°C using a two-compartment capillary cell with Ag/AgCl electrodes. The electro-osmotic water drag in HCl aqueous solutions is higher than that reported in measurements where the membrane is in contact with pure water; hence, all the reported results were performed at the same acid concentration. It was found that the drag coefficient for pure methanol is about 40% higher than that for water at all the temperatures studied as a consequence of the expanded nanostructure of Nafion in methanol. The drag coefficients of the water–methanol mixtures exhibit a high non-linearity, which can be explained by considering the Nafion sorption in the binary solvent. The electro-osmotic flow in pure methanol is similar to that of 5 M methanol aqueous solutions, which opens the opportunity to use pure methanol in DMFCs. The methanol crossover due to permeability can be minimized. Controversial results with previous studies are also addressed.

An insight about the interaction of Aryl Benzothiazoles with mild steel surface in aqueous HCl solution

The arrival of organic moieties as corrosion inhibitors has expanded the research in the past few years which, as a result; involved different heteroatoms to be tested for their anti-corrosive potential. The presented research is focused on the synthesis of the aryl-substituted benzothiazoles namely 6-(4-Chlorophenyl) benzo[d]thiazol-2-amine (CBTA), 6-(p-tolyl) benzo[d]thiazol-2-amine (TBTA), and 6-(4-methoxyphenyl) benzo[d]thiazol-2-amine (MBTA), and investigation of their anti-corrosive behaviour on mild steel in 1 M HCl particularly. Here, gravimetric and electrochemical analyses have been employed to examine the tendency of benzothiazoles to safeguard mild steel. Corrosion impeding efficacies were found to follow a significant order; MBTA > TBTA > CBTA. Further, experimental analysis unveiled the effect of substituents on corrosion mitigating potential i.e., MBTA employed the ligation of methoxy group; an enhanced electron cloud thus providing a maximum shield. The addition of corrosion inhibitors in acidic solution brought an elevation in activation energy thus retarded the rate of corrosion. Surface analysis via atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) confirmed the experimental results and attributed the presence of an adsorbed layer over mild steel surface thus providing protection from corrosion. Additionally, Quantum calculations such as density functional theory (DFT) and molecular dynamics (MD) provided an insight into the adsorption of inhibitors over mild steel at a molecular level.

Chemical durability of the iron-containing sodium borosilicate glasses

The chemical durability of the phase-separated glasses in Na2O-B2O3-SiO2-Fe2O3 system (with a constant content of SiO2 - 70 mol %; 5, 6 and 8 mol % Na2O and 2-10 mol % Fe2O3 heat treated at 550 °C) in 3M aqueous HCl solution at boiling was studied. The structure of these glasses was investigated by means of XRPD, Mössbauer and Infrared spectroscopy. Leaching of glasses containing 5 and 6 mol% Na2O in the entire studied range of Fe2O3 content, as well as glasses with 8 mol % Na2O and Fe2O3 content up to 4 mol % led to through-leaching with the production of porous glasses (PGs) in the form of plates. The coordination of Fe3+ cations affected the chemical durability. A correlation between leaching behavior and Yun-Bray-Dell (YBD) model for the chemical structure of sodium borosilicate glasses was observed. All of the glasses with interconnected phases morphology in the (1) YBD region (R = [Na2O]/[B2O3]<0.5) were suitable for through-leaching and obtaining PGs, while glasses in the (2) region were not. If the phase-separated glass composition falls into group (1) according to YBD model and the ferric ions are octahedrally coordinated, then a magnetite-containing PG can be obtained.

Synthesis of Zinc Blende-Phased CdSe Nanocrystals with Size-Tunable Optical Properties and Adjustable Valence Band Positions.

CdSe nanocrystals with average sizes of 15, 24, and 32 nm have been synthesized from an aqueous solution of Na2SeSO3, HCl, and cadmium nitrate at 15, 45, and 70 °C, respectively, for about 1 h. Mixing aqueous CdCl2, HNO3, and Na2SeSO3 at 22 °C for 4 h yields 44 nm CdSe nanocrystals. X-ray and electron diffraction analyses indicate the possession of a zinc blende crystal structure for all the samples. Despite the large particle dimensions, their absorption band red-shifts significantly from 520 to 570 nm with increasing particle sizes, and band gap values decrease from 2.03 eV for 15 nm particles to 1.68 eV for 44 nm crystals. Although these nanocrystals are not emissive, introduction of the cetyltrimethylammonium chloride surfactant during crystal growth can restore their photoluminescence attributed to the improved crystal quality, and the similarly sized CdSe nanocrystals have an emission band red-shifting from 544 nm for 15 nm particles to 583 nm for 47 nm crystals. A band diagram was constructed for these CdSe nanocrystals using information from Mott-Schottky plots. While they have close conduction band positions, the notable size-related band gap variation means that their valence band energies differ considerably with implications of electrochemical and photocatalytic properties. The 44 nm CdSe particles also show the smallest electrochemical charge-transfer resistance.

Production of Hydroxymethylfurfural Derivatives From Furfural Derivatives via Hydroxymethylation.

Hydroxymethylfurfural (HMF) derivatives such as 2,5-bis(hydroxymethyl)furan (BHMF) and furandicarboxylic acid (FDCA) are promising alternative of fossil-based diols and dicarboxylic acids for synthesis of polyesters such as polyethylene terephthalate (PET). However, high cost for preparing HMF from biomass discourages the commercialization of HMF-derived polyesters. Since producing furfural (FUR) from five-carbon sugars (e.g., xylose) via dehydration is an inexpensive and commercialized process, we herein reported a method to synthesize BHMF derivatives (5-(ethoxymethyl)furan-2-methanol (EMFM), 2,5-bis(hydroxymethyl)furan monoacetate (BHMFM) and 2,5-bis(hydroxymethyl)furan diacetate (BHMFD) from furfural derivatives, i.e., (2-(ethoxymethyl)furan (EMF) and furfuryl acetate (FA)). To avoid strong acid-induced side reactions (e.g., furan ring opening, condensation and carbonization), two reaction systems, i.e., a low-concentration HCl aqueous solution combined with formaldehyde and anhydrous acetic acid combined with paraformaldehyde, were found to be suitable for such a hydroxymethylation reaction and could lead to decent product yields. In order to improve the carbon utilization, condensed furanic byproducts were further converted into hydrocarbon fuels via a reported two-step hydrodeoxygenation (HDO) process. This study not only validates the possibility of synthesizing functional HMF derivatives (EMFM, BHMFM, and BHMFD) from commercially-available FUR derivatives (EMF and FA), but also provide a new way to transform condensed furanics to value-added hydrocarbon fuels.

Modification of Indium Tin Oxide Surface with HCl for Source/Drain Electrodes in Organic Thin Film Transistors

AbstractIn recent years, exciting advances have been achieved in pursuing organic thin film transistors (OTFTs) with high mobility. Whereas, the economical infeasibility of Au source/drain (S/D) electrodes that are widely used in OTFTs hinders the further development of OTFTs in industry. In this study, the modified indium tin oxide (ITO) as S/D electrodes is adopted. The ITO is modified by HCl aqueous solutions, its surface work function is improved from 4.8 to 5.5 eV. By first‐principle calculations and experiments, the charge analysis shows that the Cl atom traps 0.475 electrons, which indicates that In–Cl dipoles are responsible for the increase of the surface work function, besides the HCl modification leads to In+‐Cl− bonds instead of In3+‐Cl− bonds on the ITO surface compared with the reported InCl3 modification. More encouragingly, In+‐Cl− surface is found to have higher Cl density, higher work function and higher conductivity. TIPS‐pentacene, with suitable HOMO level of 5.2 eV, is adopted as organic semiconductor, and the bar‐coating process is optimized to realize oriented films. OTFTs with maximum field‐effect mobility of 0.77 cm2 V−1 s−1 are achieved. The ITO electrodes modified by HCl can be promising in the industry.

Vitamin E determination in edible oils by reversed-phase dispersive liquid-liquid microextraction and screen-printed carbon electrodes

• Rapid, simple and environmentally friendly determination of vitamin E in edible oils. • Reversed-phase dispersive liquid-liquid microextraction as ecological sample preparation. • Inexpensive and commercially available screen-printed electrodes for detection. • Analytical Eco-Scale for assessing the greenness of the method. A novel simple, environmentally friendly and portable method to determine vitamin E in edible oils based on reversed-phase dispersive liquid-liquid microextraction combined with electrochemical detection using screen-printed carbon electrodes (SPCEs) has been developed. Vitamin E was extracted from oil samples into a 4 M HCl aqueous solution and determined by differential pulse voltammetry using SPCEs. The extraction conditions optimized by experimental design (i.e., Plackett–Burman and central composite designs) were: aqueous 4 M HCl extractant volume, 43 µL; extraction time, 2 min; centrifugation time, 10 min; and centrifugation speed, 3000 rpm. The proposed method requires a standard addition calibration approach, and the working range showed good linearity from 0 to 20 mg L −1 , with a correlation coefficient ranging from 0.990 to 0.995 ( N =5). The methodological limit of detection was between 1 and 3 mg L −1 . The repeatability of the proposed method was evaluated at 15 mg L −1 , and the relative standard deviation ranged between 10 and 15% ( n =5). For the quantification of vitamin E in ten commercial samples of olive, sesame, soybean, sunflower and a mixture of sunflower and corn oils, the volume of the extractant phase (i.e., 4 M HCl aqueous solution) was increased up to 100 µL and satisfactory recoveries were obtained in the range of 85–115%, confirming the applicability of the method.

Reaction driven biomimetic sensing characteristics of polyaniline/chitosan hybrid film: Sensing chemical and electrical reaction conditions

Reaction driven biomimetic sensing characteristics of a highly electroactive polyaniline/chitosan hybrid film is presented. The coral like nanowire structures of polyaniline were grown through chitosan film matrix during in situ chemical oxidative polymerization with large cavities, which is evidenced from SEM analysis, responsible for efficient electrochemical activity. The sensing of the hybrid film reaction towards electrical as well as chemical working environment was studied galvanostatically (chronopotentiometry) at a constant charge in aqueous HCl solutions. The consumed electrical energy during the reaction has a linear dependence with applied current and semi-logarithmic dependence with electrolyte concentration. The generation of the sensing energetic signals during the electrochemical reaction of the chitosan/polyaniline hybrid film in different concentrations of the electrolyte is compared with signal generation in natural muscles (the actin-myosin molecular machines driven by chemical reactions) during working under normal state or fatigue state. The concentration sensing was further verified through potentiodynamic method (coulovoltammetry) and found that the consumed redox charge (reaction extension) varies as a double logarithmic function of the concentration. That is, the extension of the reaction involving conformational movements of the reacting polymeric chains (the molecular machines) respond to or senses the chemical reaction ambient.

Morphological and Structural Study of Anodized Titanium Grade 2, Using HCl in Aqueous Solution

In this work, the electrochemical anodization process was carried out on titanium grade 2, using an electrolytic solution of 3 M and 0.15 M HCl with voltages of 11 V, 12 V and 15 V, as well as time variations in the experimental process and later an annealing process at 750 °C. According to the results obtained, the TiO2 coatings presented different morphologies on their surface, which consisted of nanopores, nanowires and clusters of oxide grains, as well as a combination of anatase and rutile crystalline phases. Band Gap variations were found to be non-significant despite changes in the morphology of the coatings at different anodization conditions, with an average value of 2.91 eV. It was observed that the anodized samples treated by the annealing process at 750 °C, thickness values up to 16 μm were obtained.

Rapid methylation of valsartan in human plasma using evaporative derivatization reagent to improve its sensitivity in MALDI-TOF mass spectrometry.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid and low-solvent-consumption technique. However, almost every mass in the low mass-to-charge-ratio region of the mass spectrum appears as strongly fluctuating matrix background signals. Thus, it is difficult to identify small molecules using this technique. In this study, we used methanol to methylate valsartan, an angiotensin II receptor blocker that is commonly used to treat high blood pressure and heart failure. The methylation derivatization of valsartan enhanced the detection sensitivity and transformed the detection m/z ratio. The liquid-phase microextraction of valsartan in human plasma (20 μL) was achieved by acidifying valsartan with HCl aqueous solution and extracting it with toluene. An acetyl chloride/anhydrous methanol mixture was added for methylation derivatization, which was completed within 30 min at 30 °C. Finally, the residue was re-dissolved in irbesartan methanolic solution, which together with the matrix 2-mercaptobenzothiazole was spotted on an AnchorChip target plate for MALDI-TOF MS analysis. Liquid-phase microextraction was performed and the methylation-derivatization parameters were investigated. The valsartan calibration range was 0.2-10 μg mL-1 with good linearity in human plasma. In the within- and between-run analyses, the relative standard deviation and relative error were both <11.32%. This method was successfully applied to determine the valsartan concentration in the plasma of 10 patients with hypertension.

Corrosion inhibition in acidic environments: key interfacial insights with photoelectron spectroscopy.

In many engineering scenarios, surface-active organic species are added to acidic solutions to inhibit the corrosion of metallic components. Given suitable selection, such corrosion inhibitors are highly effective, preventing significant degradation even in highly aggressive environments. Nevertheless, there are still considerable gaps in fundamental knowledge of corrosion inhibitor functionality, severely restricting rational development. Here, we demonstrate the capability of X-ray photoelectron spectroscopy (XPS), supported by ab initio modelling, for revealing key details of inhibited substrates. Attention is focussed on the corrosion inhibition of carbon steel through the addition of an exemplar imidazoline-based corrosion inhibitor (OMID) to aqueous solutions of both HCl and H2SO4. Most notably, it is demonstrated that interfacial chemistry varies with the identity of the acid. High resolution Fe 2p, O 1s, N 1s, and Cl 2p XPS spectra, acquired from well-inhibited carbon steel in 1 M HCl, show that there are two different singly protonated OMID species bound directly to the metallic carbon steel substrate. In sharp contrast, in 0.01 M H2SO4, OMID adsorbs onto an ultra-thin surface film, composed primarily of a ferric sulfate (Fe2(SO4)3)-like phase. Such insight is essential to efforts to develop a mechanistic description of corrosion inhibitor functionality, as well as knowledge-based identification of next generation corrosion inhibitors.

THE EFFECT OF ALKALI AND SURFACTANT CONCENTRATION, TEMPERATURE AND STIRRING ON THE CLEANING EFFICIENCY OF THE CARBON STEEL SURFACE

Electrostatic painting is the fastest and most efficient technology through industrial paints due to its impact on the environment, and also for its very easy application on different surfaces. The first and most important stage of the electrostatic painting is to clean the surface to be painted by removing the dirt, lubricants, oils, metal oxides or welding residues. In order to increase the efficiency of carbon steel surface cleaning, the influence of alkali and surfactant concentrations, temperature and stirring was investigated. To produce a uniform surface required for the electrostatic painting, some degreased samples were subjected to pickling operation using aqueous HCl solution.

Microwave Assisted Extraction of Berberine and Preparation of Berberine Hydrochloride from Berberis Aristata Variety of Nepal, and Quantification using RP-HPLC and HPTLC Methods

Berberis aristata a Himalayan woody spiny shrub with yellow flowers and red berries commonly called as Daruharidra in Sanskrit and locally in Nepal is called as Chutro or Chitra. The root and stem are the two parts widely used in traditional medicines of India and China. Berberine is the key active ingredient present in stem and root parts. Berberine hydrochloride is the derivative of berberine. The present study aimed to study the microwave assisted extraction of berberine and its conversion into berberine hydrochloride and quantifying by RP-HPLC and HPTLC methods.In the present paper we have mentioned microwave assisted extraction of berberine and preparation of berberine hydrochloride in detail. Berberine extracted from roots of Berberis aristata using microwave assisted extraction in 80% ethanol to obtain 20% pure berberine crude by HPTLC densitometry at 350 nm absorption. The crude berberine was further purified to berberine hydrochloride by adding 10% Hcl in aqueous solution of berberine and allowed to crystallize at 5 0C over 24 hours. The crystals were further purified and recrystallized in ethanol and subjected to RP-HPLC. Reverse phase HPLC was carried out on Shimadzu UV detector at wave length of 265 nm using Acetonitrile-0.1% phosphoric acid solution (50:50) (add 0.1g sodium dodecyl sulfonate per 100ml) as the mobile phase; Phenomenex RP-column (250 mm × 4.6 mm, 5 μm), With flow rate 1.0 mL/minute, 5 µL injection volume, column temperature 25 0C for run time of 35 minutes, and retention time of berberine hydrochloride was 12.008 minutes with purity of 82% and recovery of 90% yield obtained.

Characterization of polyanilines synthesized at different pH for electrochemical sensing and supercapacitor applications

Here we synthesized different polyanilines from the aqueous HCl solutions of different pH through chemical oxidative polymerization of aniline using potassium persulphate as oxidant at 10 ± 2 °C. The polymers were characterized using UV–Visible spectra, FT-IR and SEM. The dependence of pH of the acid medium used for the synthesis on the electrochemical characteristics - specific capacitance and current sensing of the synthesized polyanilines were studied by cyclic voltammetric and chronopotentiometric techniques. Polyaniline experiences a sharp drop in its performance as a supercapacitor when it is synthesized from a higher pH medium. The highest specific capacitance was obtained for polyaniline synthesized from pH = 0 medium. We have also verified that the electrochemical reactions of all the synthesized polyanilines can sense their electrical working energetic conditions. The sensing capabilities (here the current sensing) of polyanilines synthesized at different pH showed a linear relationship between the consumed electrical energy and the applied current. The current sensitivity of polyaniline slightly decreases as the pH of reaction media increases from 0 to 2 and markedly decreases for polyaniline from solutions of pH above 2.

Incorporating Sulfur Atoms into Palladium Catalysts by Reactive Metal–Support Interaction for Selective Hydrogenation

Incorporating Sulfur Atoms into Palladium Catalysts by Reactive Metal–Support Interaction for Selective Hydrogenation

Hematite as an Electrocatalytic Marker for the Study of Archaeological Ceramic Clay bodies: A VIMP and SECM Study**

AbstractThe electrocatalytic effect exerted by hematite, a ubiquitous component of clay bodies, on the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) can be used to acquire information on archaeological ceramics. The solid‐state voltammetric response of different hematite and ochre specimens, accompanied by SECM analysis in contact with 0.10 M HCl aqueous solution, is described. In air‐saturated solutions, catalytic effects on the ORR and OER are accompanied by Fe(III)/Fe(II) and Fe(IV)/Fe(III) redox reactions. Such processes are conditioned by a variety of factors, the hydroxylation degree of the mineral surfaces being particularly influential, and exhibit significant variations upon heating the specimens between 300 and 900 °C. Voltammetric measurements carried out on a set of archaeological samples of Apulian red‐figured pottery dated back within 5th and 4th centuries BCE permit to obtain site‐characteristic voltammetric profiles.