Hydrochloric Acid System Research Articles

Surface morphology studies and kinetic-thermodynamic characterization of steels treated in 5.0 M HCl medium: hot-dip galvanizing application

PurposeThe purpose of this paper is to study the effect of silicon and phosphorus content in steel suitable for galvanizing on its corrosion and inhibitor adsorption processes in steels/cetyltrimethylammonium bromide combined and KI (mixture)/5.0 M hydrochloric acid systems has been studied in relation to the temperature using chemical (weight loss), Tafel polarization, electrochemical impedance spectroscopy (EIS), scanning electronic microscope (SEM) analysis and Optical 3D profilometry characterization. All the methods used are in reasonable agreement. The kinetic and thermodynamic parameters for each steels corrosion and inhibitor adsorption, respectively, were determined and discussed. Results show that the adsorption capacity for Steel Classes A and B are better than Steel Class C surfaces depending on their silicon and phosphorus content. Surface analyses via SEM and Optical 3D profilometry was used to investigate the morphology of the steels before and after immersion in 5.0 M HCl solution containing mixture. Surface analysis revealed improvement of corrosion resistance of Steels Classes A and B in the presence of mixture more than Classes C. It has been determined that the adsorbed protective film on the steels surface heterogeneity markedly depends on steels compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content.Design/methodology/approachThe effect of silicon and phosphorus content in Steels Classes A, B and C on its corrosion and inhibitor mixture adsorption processes in 5.0 M HCl solution has been studied by weight loss, potentiodynamic polarization, EIS and surface analysis.FindingsThe inhibition efficiency of mixture follows the order: (Steel Class A) > (Steel Class B) > Steel Class C) and depends on their compositions in the absence of mixture according on their silicon and phosphorus content, that is, the corrosion rate increases with increasing of the silicon and phosphorus content. A potentiodynamic polarization measurement indicates that the mixture acts as mixed-type inhibitor without changing the mechanism of corrosion process for the three classes of mild steels.Originality/valueCorrosion rate mild steels in 5.0 M HCl depends on their compositions in the absence of mixture according to their silicon and phosphorus content, that is, the corrosion rate increases with increasing silicon and phosphorus content. The adsorbed protective film on the steels surface heterogeneity markedly depends on steels class’s compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content.

ЭКСТРАКЦИОННО-ФОТОМЕТРИЧЕСКОЕ ОПРЕДЕЛЕНИЕ МЕДИ (II) С 1,2,3-БЕНЗОТРИАЗОЛОМ В СИСТЕМЕ ВОДА – АЛКИЛБЕНЗОЛСУЛЬФОКИСЛОТА – ХЛОРОВОДОРОДНАЯ КИСЛОТА

Optimal concentration parameters of the extraction process in the water – alkylbenzenesulfonic acid – hydrochloric acid system in the presence of 1,2,3-benzotriazole (БТА) were found out. The total system volume (up to 50 ml) contained ABSA and BTA at the ratio 3:4 (0,6 g of ABSА and 0,8 g of BTA), at concentration of HCl varying from 0 to 0,1 mol L-1. The possibility of extraction-photometric determination of 92–740 μg of copper (II) in the system was established.

Hydrodynamics and kinetics in semi-batch stirred tank precipitation of l-glutamic acid based on pH shift with mineral acids

The precipitation process of l-glutamic acid from monosodium glutamate solution through acidification is studied by using hydrochloric acid and sulphuric acid. Both experimental and modelling methods are applied. The experiments have been carried out with a single feed semi-batch process applying two acid feed rates and two rotational mixing speeds. The method for computational fluid dynamics (CFD) modelling of the semi-batch process with a changing fluid volume is presented. The precipitation process including nucleation and crystal growth is modelled with CFD by using the kinetics presented in the literature for hydrochloric acid. A model for agglomeration presented in the literature and Eddy Dissipation Concept for micromixing are applied in the case of a lower rotational speed and hydrochloric acid. The particle size distribution is modelled with the simple number density model and with Quadrature Method of Moments. Micromixing was found to have an insignificant effect, but when including the model for agglomeration, the particle size distribution was in better agreement with the experiments. However, pH evolution of the system was captured better without the agglomeration model, indicating that the kinetic model may not describe the precipitation accurately. The pH and saturation ratio Sα were modelled based on thermodynamics. The significance of activities is highlighted in computing the thermodynamic equilibrium, and in precipitation kinetics. It was found that the applied acid had an effect on the chemical process, although the species concentrations were the same. The difference of the kinetic models between hydrochloric acid and sulphuric acid could be explained by the more complex dissociation of sulphuric acid. The greater computational ionic strength with sulphuric acid increased the nucleation rate, resulting in a difference in pH evolution in comparison with hydrochloric acid. Therefore, the kinetic parameters determined for the hydrochloric acid system are not applicable for other acid systems with different chemical compositions. For the modelling of the precipitating systems, more experimental work is needed for determining the kinetics.

Nucleation/growth mechanism of electrocrystallization for As–Sb alloy in hydrochloric acid system

Abstract The initial electrocrystallization of As–Sb alloy on glass carbon (GC) electrode in hydrochloric acid system was studied via cyclic voltammetry (CV) and chronoamperometry measurements. Current transients were presented in dimensionless formation, which showed that the initial nucleation/growth process of As–Sb alloy followed three-dimensional nucleation model with diffusion-controlled growth. Relevant nucleation parameters were calculated by analyzing related current transients. Particular attention was paid to the effect of Sb(III) concentration on the nucleation process during the co-electrodeposition. The quantitative results showed that Sb(III) played a positive effect on enhancing the nucleation rate of As–Sb alloy, leading to the evolution of alloy surface morphology from grain structure to compact layer structure.

Phase and extraction equilibria in H2O–sulfonol–HCl (H2SO4) and H2O–sodium dodecyl sulfate–HCl (H2SO4) systems

Solubility isotherms of water–sulfonol–hydrochloric (or sulfuric) acid and water–sodium dodecyl sulfate–hydrochloric acid systems at 75°C and a water–sodium dodecyl sulfate–sulfuric acid system at 50°C are constructed. Regions of two-phase liquid equilibrium suitable for use in extraction are found. Concentration parameters for extraction are determined. The interfacial distribution of a series of metal ions with and without such additional complexing reagents as diantipyrylmethane and diantipyrylheptane is studied.

Acid Leaching of Malachite Ore and Separation of Cu(II) by di-(2-Ethylhexyl) Phosphoric Acid and Tributyl Phosphate in Acetate Buffer Solution

Copper extraction from malachite ore by leaching and solvent extraction was examined. The leaching experiments were performed by sulphuric acid, hydrochloric acid and mixed reagent system. The iron impurity in the leach liquor had adverse effects on the copper extraction, therefore, iron separation from sulphate and mixed sulphate/chloride leach liquors was done using Tri-n-butyl-phosphate (TBP) and methyl-iso-butyl-ketone (MIBK). This indicated that it was possible to remove more than 95 % of iron content using 70 % TBP and 30 % MIBK. After iron removal, copper extraction was performed for various temperatures at different pH values from aqueous acetate buffer solutions with di-(2-ethylhexyl) phosphoric acid 20 % (V/V) dissolved in hexane. The results indicated that acetate ion had the maximum effect at pH 4.5. Thus, it could be mentioned that pH was the most important factor and that it was possible to recover more than 90 % of the copper from leach liquor under the optimum leaching condition.

Effective cementation and removal of arsenic with copper powder in a hydrochloric acid system

This work investigated the removal and cementation of arsenic from a hydrochloric acid system with copper powder.

Determination of radioisotopes in complex saline matrices using extraction chromatography and liquid scintillation counting

The retention of 239Pu and 241Am on six commercially available extraction chromatographic resins was investigated to determine the effect of matrix constituents commonly found within sea and ocean water on their uptake. It was found that the retention of 239Pu and 241Am on almost all of the resins from either nitric acid or hydrochloric acid system was not significantly affected by matrix constituents in artificial ocean water. However, the retention of 241Am on DGA resin from nitric acid was found to be reduced by over two orders of magnitude in the presence of artificial ocean water.

Copper-promoted cementation of antimony in hydrochloric acid system: A green protocol

A new method of recovering antimony in hydrochloric acid system by cementation with copper powder was proposed and carried out at laboratory scale. Thermodynamic analysis and cyclic voltammetry test were conducted to study the cementation process. This is a novel antimony removal technology and quite meets the requirements of green chemistry. The main cement product Cu2Sb is a promising anodic material for lithium and sodium ion battery. And nearly all consumed copper powder are transformed into CuCl which is an important industrial material. The effect of reaction temperature, stoichiometric ratio of Cu to Sb(III), stirring rate and concentration of HCl on the cementation efficiency of antimony were investigated in detail. Optimized cementation condition is obtained at 60°C for 120min and stirring rate of 600rpm with Cu/Sb(III) stoichiometric ratio of 6 in 3molL−1 HCl. At this time, nearly all antimony can be removed by copper powder and the cementation efficiency is over 99%. The structure and morphologies of the cement products were characterized by X-ray diffraction and scanning electron microscopy, respectively. Results show that the reaction temperature has little influence on the morphology of the cement products which consist of particles with various sizes. The activation energy of the cementation antimony on copper is 37.75kJmol−1, indicating a chemically controlled step. Inductively coupled plasma mass spectrometry results show that no stibine generates during the cementation process.

The corrosion inhibition effect of aryl pyrazolo pyridines on copper in hydrochloric acid system: computational and electrochemical studies

The inhibition effect of three aryl pyrazole pyridine derivatives (APPs) against the corrosion of copper in 0.5 M HCl has been investigated by electrochemical impedance, potentiodynamic polarization measurements and quantum chemical methods.

Solvent Extraction of Iron(III) with Tri Methyl Amine from Mineral Acid Solutions

Solvent extraction of iron(III) was carried out with 2.5x10 -2 M of Tri methylamine in chloroform from hydrochloric, sulphuric and nitric acid solutions. After extraction iron(III) was stripped from the organic phase with 1.0 M H2SO4 and was determined using AAS method. The extractions were quantitative with hydrochloric and nitric acid systems and 95% from sulphuric acid solutions employed in the study. Based on the results obtained, estimation of iron in natural and industrial samples has been attempted.

Solvent extraction of Zr and Hf from hydrochloric acid using tributylphosphate for the extraction of element 104, rutherfordium

SummaryFor the solvent extraction experiment on element 104 (Rf), solvent extraction of Zr and Hf as its homologues was performed in tributylphosphate (TBP)/hydrochloric acid (HCl) system using the carrier-free radiotracers88Zr and175Hf. Time dependences of the distribution ratios of Zr and Hf were investigated using 6.1 and 10.0M HCl and 0.5 and 2.0M TBP benzene solutions. The distribution ratios in equilibrium were determined for these elements as a function of HCl concentrations in the range of 4.1-10.2M. We found that the neutral chloride complexes of Zr and Hf were formed and extracted into the organic phase within 20 min in HCl with a concentration higher than 6 M. From the results, we propose that solvent extraction of Rf from 4-8M HCl into 2.0M TBP benzene is suitable for investigating the chloride complexation properties of Rf. In addition, for the development of the rapid liquid-liquid extraction apparatus, three types of microchannel devices, namely, a micro reactor, capillary tube and micro-chemical chip, were tested as a mixing-solution part in the apparatus. The chemical reactions of Zr and Hf in the extraction were found to be fast only when using the microchemical chip, which is important for investigations with the 68-s261Rf.

Роль оксиду азоту і таурину у регуляції секреторної функції шлунка собак

The influence of taurine and endogenous nitric oxide on the gastric secretion and secretory process alterations by taurine at the nitric oxide synthesis blockade was investigated in chronic experiments on dogs with gastric fistulas. We determined the intensity of gastric secretion during 1,5 hours and quantitative content of hydrochloric acid, pepsine, total proteins and adenile system components. The NO-synthase inhibition by L-NAME evoked an increase of secreted gastric juice volume stimulated by histamine by 160% (P<0,001), the gastric acid content - by 156,4% (P<0,001), pepsine content - by 184,1% (P<0,001) as compared with control. Taurine increases the volume of gastric juice stimulated by histamine on 129,3% (P<0,001), hydrochloric acid - by 151,4% (P<0,001), pepsine - by 172,2% (P<0,001), total proteins - by 60,5% (P<0,001) as compared with control. Blockade of nitric oxide synthesis did not alter the effect of taurine on histamine gastric secretion. The present results suggest that the endogenous nitric oxide provides an inhibitory influence on gastric secretion and did not participate in realization of regulatory effects of taurine on gastric secretory function.

Carbon nanodots sensitized chemiluminescence on peroxomonosulfate–sulfite–hydrochloric acid system and its analytical applications

In the present work, new water-soluble fluorescent carbon nanodots (C-dots) were prepared in a facile microwave pyrolysis approach in minutes by combining glycine and polyethylene glycol 200 (PEG 200). Transmission electron microscopy (TEM) measurements showed that the resulting C-dots had diameters of about 3nm. 13C NMR spectra further confirmed the presence of carbons (sp2 and sp3) indicating a nanocrystalline core of the resulting C-dots with hydroxyl of PEG 200 covered outside. It was discovered that the prepared C-dots could dramatically enhance the chemiluminescence (CL) intensity of potassium peroxomonosulfate–sodium sulfite–hydrochloric acid (PSHA) reactions. UV–vis absorption and photoluminescence (PL) spectra indicated that the C-dots sensitized enhancements originated from their energy transfer and electron-transfer annihilation effects on the CL system. When the concentration of C-dots was 4×10−5M, and those of KHSO5, Na2SO3 and HCl were 1×10−2M, an excellent performance was obtained. The C-dots sensitized CL system was successfully applied to the determination of aliphatic primary amines in real water samples with satisfactory results.

Chloride leaching of a complex matte: comparison of oxidants

The leaching of a complex matte in chlorine and chloride media was studied. The matte was prepared from manganese nodules by the reduction smelting-sulfidation route. From XRD analysis, the major phases of the matte were identified as CuFeS2, CuS2, (FeNi)9S8, (FeNi)S2, Ni9S8, Ni3S2, (CoFeNi)9S8 and Co metal. Investigated were the chlorine, hydrochloric acid, hydrochloric acid-oxygen, ferric chloride, ferric chloride-oxygen, cupric chloride and cupric chloride-oxygen systems. The results are discussed in terms of reagent concentration retention time, leach temperature and gas sparging rate. The chlorination process resulted >99% metal extraction efficiency within a short retention time and at atmospheric temperature. However, there were no preferential extractions of Cu, Ni and Co with respect to Fe. The cupric chloride-oxygen system produced leach liquors with the lowest Fe content and with a high base-metal extraction. Sulfide sulfur was converted to mixtures of elemental sulfur and sulfate in all the studied systems.

Electrodeposition of Bi xSb 2− xTe y thermoelectric thin films from nitric acid and hydrochloric acid systems

The electrochemical behaviors of Bi III, Te IV and Sb III single ions and their mixtures were investigated in nitric acid and hydrochloric acid system separately. Based on which, Bi x Sb 2− x Te y thermoelectric films were prepared by potentiostatic electrodeposition from the solutions with different concentrations of Bi III, Te IV and Sb III in the two acid systems. The morphologies, compositions, structures, Seebeck coefficients and resistivities of the deposited thin films were characterized and compared by ESEM (or FESEM), EDS, XRD, Seebeck coefficient measurement system and four-probe resistivity measuring device respectively. The results show that although Bi x Sb 2− x Te y thermoelectric thin film which structure is consistent with the standard pattern of Bi 0.5Sb 1.5Te 3 can be gained in both of the two acid solutions by adjusting the deposition potential, their morphologies and thermoelectric properties have big differences in different acid solutions.

Hydrogen bonds and ionic interactions in Guanidine/Guanidinium complexes: a computational case study

It is frequently said that hydrogen bonds (HBs) are enhanced by ionic interactions and in this article we intend to determine the degree at which this reinforcement happens. Considering our interest in the Guanidine(neutral)/Guanidinium(cation) system and its particular nature, all the possible 1:1 complexes with the Chloride(anion)/Hydrochloric acid(neutral) system have been studied at different levels of computation (B3LYP with 6-31+G* and TZVP basis sets; MP2 with 6-31+G*, 6-311++G** and aug-cc-pVDZ basis sets; CBS-QB3 and G3MP2). The nature of these interactions established in all the systems and, when possible, at all the levels of computation used in this study, has been analyzed using Atoms in Molecules and Natural Bond Orbital methodologies. By examining the interaction energy, the electron density at the bond critical bonds, the atomic energy, the charge transfer, the orbital energy, and the deformation energy we can conclude that HBs are stronger when the ionic interaction is stronger. Thus, both interactions do not work in an independent manner but one reinforces the other to different degrees depending on the nature of the charges present. Several correlations with the interaction energy have been found and a partition of the contributions of both the HB and ionic forces to the total interactions is proposed.

Thermodynamic study of metal corrosion and inhibitor adsorption processes in mild steel/1-methyl-4[4′(-X)-styryl pyridinium iodides/hydrochloric acid systems

The corrosion and inhibitor adsorption processes in mild steel/1-methyl-4[4′(-X)-styryl] pyridinium iodides (X: H, CH 3 and OCH 3)/hydrochloric acid systems was studied at different temperatures (25–60 °C) by means of hydrogen evolution (HE) and weight loss (WL) measurements. It was found that the studied compounds exhibit a very good performance as inhibitors for mild steel corrosion in 1.5 M HCl. Results show that the inhibition efficiency increases with decreasing temperature and increasing concentration of inhibitors. Good agreement between the results obtained from hydrogen evolution and weight loss measurements was appeared. It has been determined that the adsorption for the studied inhibitors on mild steel complies with the Langmuir adsorption isotherm at all studied temperatures. The kinetic and thermodynamic parameters for mild steel corrosion and inhibitor adsorption, respectively, were determined and discussed. On the bases of thermodynamic adsorption parameters, comprehensive adsorption (physisorption and chemisorption) for the studied inhibitors on mild steel surface was suggested. A good correlation between the substituent type and the inhibition efficiency of inhibitors through the application of Hammet relationship was obtained. Results show that with increasing the donor property of the substituent, the inhibition efficiency of the inhibitor is increased in the order: I-H < II-CH 3 < III-OCH 3.

Kinetics of amoxicillin and clavulanate degradation alone and in combination in aqueous solution under frozen conditions

Kinetics of the reactions of amoxicillin sodium and potassium clavulanate alone and in combination were investigated in the frozen state at selected pH values of 2.0, 4.6 and 7.0. Extrapolation of the rate constant values to the frozen state from the liquid state data indicated marked acceleration of the rates of amoxicillin and clavulanate degradation for the pH values investigated. The highest acceleration in rate recorded was 15.0-fold for clavulanate and the lowest value was 4.6-fold for amoxicillin at −7.3 °C in the hydrochloric acid system. The rate constant values obtained were interpreted in terms of the concentration model [Pincock, R.E., Kiovsky, T.E., 1966. Kinetics of reactions in frozen solution. J. Chem. Educ. 43, 358–360], phase–temperature relationship of the solutes, buffer catalysis, pH change and polymerization reactions. A kinetic model was deduced for the hydrochloric acid system providing adequate explanation of the experimental results. A large stabilizing effect of sodium chloride used for maintaining constant ionic strength ( μ = 0.5) was evident in this system. The shelf-life of amoxicillin was increased from 2.2 to 58.7 h at −7.3 °C when sodium chloride was included in the hydrochloric acid system.

Determination of triadimenol based on the quenching effect on resonance light scattering from the triadimenol–deoxyribonucleic acid–hydrochloric acid system

Analysis of triadimenol was carried out using deoxyribonucleic acids (DNA) via the resonance light scattering (RLS) technique. After adding triadimenol into aqueous medium of pH 1.72, the RLS of DNA was remarkably quenched. A resonance light scattering peak at 310 nm was found, and the quenched intensity of RLS at this wavelength was proportional to the concentration of triadimenol. The linear range of the calibration curve was approximately 0-3 microg mL-1 with a detection limit (S/N=3) of 0.07 microg mL-1. The triadimenol in samples of water, cucumber and human serum was determined. The results were satisfactory, and the recovery rates were in the range of 96.3-106.0%, 94.8-105.9% and 92.3-100.5%, respectively. The interaction mechanism was also studied.