Hydrochloric Acid System Research Articles

Pre-treatment of Remelting Recovery: Ultrasonic Cleaning Mechanism of Non-metallic Layers from Superalloy Scrap Under Based on Hydrochloric Acid and Potassium Iodide Solution System

Pre-treatment of Remelting Recovery: Ultrasonic Cleaning Mechanism of Non-metallic Layers from Superalloy Scrap Under Based on Hydrochloric Acid and Potassium Iodide Solution System

Corrosion behaviour of 110SS steel in hydrochloric acid and blended acid system at 200°C

The influence of organic acids (formic acid, acetic acid) on the corrosion behaviour of 110SS steel, a hydrogen sulphide corrosion resistant alloy steel, in hydrochloric (HCl) acid environments was studied. The corrosion rates of 110SS steels in HCl acid and blended acid were measured using the high-temperature and high-pressure corrosion tester. Scanning electron microscopy was utilised to observe the morphology of corrosion products on steel samples corroded by different acid systems, and the energy dispersive X-ray spectrometer was used to analyse the elemental composition of the corrosion products. The corrosion morphology was observed using a 3D laser scanner. The results indicated that the corrosion rate of 110SS steel in HCl acid at 200 °C was an exponential function of HCl concentration. Reducing the HCl concentration significantly decreased the corrosion rate of 110SS steel. Organic acids and corrosion inhibitors synergistically reduced the corrosion of 110SS steel in HCl acid. Adding 3 wt.% organic acid to the 15 wt.% HCl acid system further reduced the corrosion rate, with a more pronounced effect observed in the HCl–formic acid system compared to the HCl–acetic acid system. Organic acids chemically adsorbed onto the steel surface and decomposed to produce CO, which hindered the attack of hydrogen ions on the metal. The added corrosion inhibitor and intensifier Sb2O3 resulted in the formation of a compact adsorption film on the steel surface, further inhibiting corrosion. The optimal mass ratio of HCl acid to organic acid was found to be 15% to 3%.

Environmentally friendly non-saponification solvent extraction and separation process for RE(III) (RE = Eu, Gd and Tb) in acetic acid solution using HEHEHP/n-heptane

The key to achieving sustainable metal extraction development is to avoid the generation of high-salt wastewater from the source. Here, a new system for the extraction and separation of lanthanide elements Eu(III), Gd(III) and Tb(III) from the acetic acid solution using HEHEHP (2-ethylhexyl hydrogen-2-ethylhexylphosphonate) was studied. The corresponding parameters including contact time, HEHEHP concentration, concentrations of rare earth metal ions and acetic acid in the initial solution, aqueous/organic phase volume ratio (R(A/O)), and temperature were considered to optimize the conditions for the separation of different rare earth elements. The results showed that the separation coefficients of Tb(III)/Gd(III) and Gd(III)/Eu(III) in the acetic acid system were approximately 6.2 and 1.7, with HEHEHP of 0.15 mol/L and R(A/O) of 2:1, and the extraction efficiency of RE(III) reached approximately 73.1%, which was higher than that in the hydrochloric acid and sulfuric acid systems. The mechanism associated with the extraction reaction was evaluated and discussed by the maximum loading capacity method, chromatographic analysis, and FT-IR spectrometric analysis. The mechanism followed a cation exchange reaction and acetic acid did not participate in the extraction process. The feasibility of the separation of Tb(III) from Eu(III) and Gd(III)was also given in terms of the separation coefficients between different elements at different extraction conditions. Since saponification is not necessary in the acetic acid extraction system, it can considerably reduce wastewater discharge to the ecological environment from the source.

Efficient extraction of platinum(IV) using tertiary-amine groups functionalized thiacalix[4]arene as extractant

In the present study, the extraction performance and complexation mechanism of p-di-ethyl-amino-methyl-thiacalix[4]arene (L) toward Pt(IV) in a hydrochloric acid system were investigated. The effects of various parameters including solution pH, L to Pt(IV) mole ratio, Cl− concentration, acidity and reaction time on the complexation process of L with Pt(IV) were systematically investigated. The experimental results indicated that L has excellent complexation ability toward Pt(IV) that about 90 % of Pt(IV) could be extracted within 2 min under the optimal conditions. Moreover, L could selectively extract Pt(IV) from the HCl system containing multiple competing ions such as Ce(III), Zr(IV), La(III), Fe(III), Ni(II), Mg(II), and Al(III). The complexation mechanism between L and Pt(IV) was further clarified by slope analysis, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), and proton nuclear magnetic resonance (1H NMR) titrations. Theoretical analysis of thermodynamics, complexation structure and intermolecular interactions between L and Pt(IV) during the solvent extraction process were performed through density functional theory (DFT) calculations. The results showed that the protonation of L occurs first to form the complex of L·2HCl, which further reacts with PtCl62− forming the complex of L·2H+·PtCl62− through anion-exchange, achieving the efficient and selective extraction of platinum.

Achieving Ultrahigh Efficiency Vacancy-Ordered Double Perovskite Microcrystals via Ionic Liquids.

Lead-free perovskites have gained much interest for photovoltaic and optoelectronic applications. But instability and low quantum efficiency significantly limit their prospects for future applications. Here, a general route is reported to synthesize highly stable lead-free perovskites on a large scale with remarkably enhanced quantum efficiency. Two typical vacancy-ordered double perovskites (Cs2 ZrCl6 and Cs2 SnCl6 ) and their corresponding Bi3+ or Sb3+ doped samples are synthesized in ionic liquids (ILs) solutions via a simple solution method. These prepared perovskite samples all exhibit high-quality crystalline structures and their photoluminescence quantum yields (PLQYs) all show an increase close to 200% compared to the samples prepared in the hydrochloric acid system. The PLQY of Sb-doped Cs2 ZrCl6 with excellent thermal stability can reach up to 90.2%, which is the highest value reported for this system (Cs2 ZrCl6 :Sb). Density functional theory calculations reveal that the corresponding interaction between the ILsand the samples can effectively improve the crystal quality and reduce energy loss. The potential applications of the prepared samples for high-performance white light-emitting diodes and optical anti-counterfeiting are also demonstrated. The findings provide a straightforward way to obtain ultrahigh quantum efficiency vacancy-ordered double perovskites with good thermal stability and excellent optoelectronic properties.

Effect of organic and inorganic compounds on dissolution kinetics of chalcopyrite in hydrogen peroxide– Hydrochloric acid system

The addition of 2-Propanol as an organic substance and NaCl as an inorganic compound in hydrochloric acid with hydrogen peroxide as a strong leaching agent of chalcopyrite was investigated. The effects of the leaching parameters on copper extraction, such as stirring speed, H2O2 concentration, temperature, HCl concentration and solid/liquid ratio were studied. The maximum final copper extraction of 54.55% was obtained with 600 rpm stirring speed, 1.5 M H2O2, 0.5 M HCl, 600 rpm, 50 °C, 240 min of the reaction and particle size of −106 +75 µm. Further experiments were performed when the solid-to-liquid ratio (S/L), stirring speed, temperature, HCl, H2O2 and leaching time were kept constant to examine the influence of NaCl and 2-Propanol concentrations in the range of 0–0.5 M and 0–3 M, respectively. The results showed that the copper extraction was increased up to 58.11% with addition of NaCl. While copper extraction yield reached 94.25% in case of addition of 2-propanol with the optimum parameters(0.5 M HCl,50 °C, 1.5 M H2O2, 600 rpm, particle size −106 +75 μm, solid liquid ratio 2g/L, 3 M 2-propanol). The chalcopyrite leaching in hydrogen peroxide– hydrochloric acid system was found to be described by the interface transfer and diffusion across the product layer with activation energy of 77.14 kJ/mol. Addition of 2-propanol suggested that the reaction was under product layer diffusion control and decreased the activation energy of chalcopyrite leaching to 67.98 kJ/mol.

Electrochemical reduction of uranium and rhenium in hydrochloric acid system

Abstract The electrochemical reduction of U(VI) and Re(VII) ions on Pt and Mo metals are discussed. The electrochemical behavior of U(VI) and Re(VII) in hydrochloric acid media was investigated using various electrochemical techniques. By analyzing the cyclic voltammogram of U(VI) and Re(VII) recorded on Pt electrode, a series of electrochemical reactions associated with uranium and rhenium were recognized, indicating that U(VI) and Re(VII) undergoes a single-step electron and multistep electron process under experimental conditions, respectively. The reduction of U(VI) and Re(VII) was found to be controlled by charge transfer and diffusion in hydrochloric acid media. The diffusion coefficient of U(VI) and Re(VII)was determined to be 4.22–5.99 × 10−6 cm2 s−1 and 1.50–2.90 × 10−5 cm2 s−1, respectively, and the activation energy for the diffusion are calculated to be 18.12 kJ mol−1 and 14.52 kJ mol−1 by cyclic voltammetry at different temperatures. The reduction process of U(VI) and Re(VII) at hydrochloric acid is further studied by potentiostatic electrolysis. It is feasible to realize the reduction of uranium and rhenium from aqueous solution by electrolysis.

Development of Continuous Gas Generation Method for Hydrogen Chloride Using Azeotropic Hydrochloric Acid System

Standard gases are often prepared using high-pressure gas cylinders. However, it is difficult to accurately prepare a known concentration of hydrogen chloride (HCl) gas using this method because HCl is highly corrosive and adsorptive. In this study, a simple method for the continuous generation of HCl gas was developed using a diffusion tube containing hydrochloric acid and a nitrogen carrier gas. The concentration of HCl produced from this system was almost unstable, but constant gas generation was realized for several hours when azeotropic hydrochloric acid (20.6% HCl in water) and a temperature near the azeotropic point (108.5 °C) were used, resulting in the generation of 103.6 ppm (mean, n = 5) of HCl gas with a relative standard deviation (RSD) of 2.34%. In this case, the percentage of HCl present in the entire gas mixture of HCl and water vapor was 22.5%, which is almost equivalent to the HCl content in the azeotropic hydrochloric acid (20.6%). The HCl concentration could also be controlled by changing the flow rate of the carrier gas. This work demonstrates a simple technique based on the diffusion theory that allows for the constant, controllable generation of a known concentration of HCl gas using an azeotropic hydrochloric acid system.

Use of chelators and hydrofluoric acid for the improvement of well productivity

The paper presents the results of microscopic analysis of the content of elements on the surface of clay samples after treatment with an acidic mixture of HV:HF. The analysis showed that as a result of the dissolution of clay and quartz, quartz dissolves faster, the Si/Al ratio on the sample surface decreased, which indicated the formation of a protective film of aluminum phosphate silicate. The studies of the ability of chemical reagents to dissolve clay by the method of weight loss showed that in the HV:HF system, the dissolution rate of clays is much lower due to the formation of a coating layer. The stage of the increase in the rate of dissolution occurs when a part of this layer is dissolved. The studies of the ability of the HV:HF chemical reagent system to dissolve silicon showed that the amount of dissolved silicon varied linearly with the exposure time and the rate of silicon dissolution was proportional to the HF concentration in the system. The dissolution rate of silicon in the HV:HF system is much higher than in the HCl:HF system at the same HF concentration. This is a significant advantage of the proposed system of chemical reagents HV: HF in comparison with the traditional HCl:HF system. HV: HF system dissolves calcium carbonate much more efficiently than traditional hydrochloric or acetic acid systems.

Efficient recovery of Au(III) through PVDF-based polymer inclusion membranes containing hydrophobic deep eutectic solvent

A novel extractant, hydrophobic deep eutectic solvent (DES) has been synthesized by mixing tetraoctylphosphonium bromide (P8888Br) and di-(2-ethylhexyl) phosphoric acid (P204), and then used as carrier to prepare a homogenous and flexible polyvinylidene fluoride (PVDF)-based polymer inclusion membrane (PIM) for the recovery of Au(III) in hydrochloric acid system. A series of characterizations and conditions optimization experiments have been performed on the elaborated PIMs. It was found that PIM composed of 70 wt% PVDF, 5 wt% NPOE and 25 wt% DES had excellent selectivity and could achieve the quantitative extraction of Au(III) from mixed metals solution. Under the optimal conditions, 99.1% of gold in the feed phase was selectively transported to the receiving phase by the optimized PIM with a high permeability coefficient of 3.52 × 10−5 m s−1, realizing the enrichment and recovery of gold. Besides, the elaborated PIM had high reusability and stability, which still had an extraction efficiency of 92.4% after five consecutive transport experiments. These results all confirm the advantages of the newly developed PIM in the extraction and recovery of gold, and it will be expected to realize a wide range of economic and practical value.

Miniaturized application of 3D‐printed large‐flow microreactor in extraction and separation of platinum, palladium and rhodium

AbstractProblems of long extraction time, large footprint, low single‐stage extraction efficiency, and complicated production processes in solvent extraction equipment in recycling of modern industrial precious metal waste liquids are addressed and application of miniaturized equipment to hydrometallurgy is proposed in this study. A 3D‐printed multichannel microfluidic reactor will likely replace traditional extraction equipment. The reactor was applied to experiments concerning tributyl phosphate extraction and separation of platinum, palladium and rhodium precious metal ions in a hydrochloric acid system. Results showed that, under the conditions of a ratio of 1:1 and a flow rate of 192.5 mL min‐1 (processing capacity of 1.5L h‐1), the extraction rates of platinum and palladium are 84.26% and 96%, and the separation coefficient is βPt/Rh and βPd /Rh is 132.35 and 753.5,moreover, the optimized extraction rate of platinum and palladium in the reactor increases by 2% and 1%, respectively. Hence, the extraction effect of this reactor is better than conventional industrial single‐stage extraction (extraction time 12min, platinum extraction rate 87.43%, palladium extraction rate 90.86%, separation coefficients βPd/Rh and βPt/Rh are only 65.3 and 45.7). In summary, compared with conventional extraction, microreactor extraction can increase the separation coefficient, shorten the extraction time, and the total processing capacity can reach the industrial production level. In addition, this study also discussed the influence of microreactor structure optimization on the extraction effect. © 2020 Society of Chemical Industry

Asphaltenes behavior during petroleum reservoirs acidizing (a molecular-scale onset study)

In the present study, we report our findings on asphaltenic sludge formation onset during petroleum reservoir acidizing treatment. To achieve this goal, we perform a series of molecular dynamics (MD) simulations at high temperature and pressure (550 K, 200 bar) on asphaltenic-oil (containing different molecular structures of asphaltenes) /hydrochloric acid (HCl) systems. Our simulation results indicate formation of asphaltenic sludge onset due to reservoir acidizing. Accumulation of the ionized asphaltenes at the oil/aqueous interface is the cause of sludge formation onset. Presence of ionized asphaltenes at the oil/water interface is attributed to the strong ion-ion interaction between ionized asphaltenes and acid ions (H+ and Cl-). Sludge formation onset is further stabilized via hydrogen bonding forces between ionized asphaltenes and interfacial water.

The efficient separation of thorium from rare earth using oxamic acid in hydrochloric acid medium

Thorium (Th) is a promising element that can be converted to fissile uranium for nuclear energy. A large amount of slag containing Th need to be effectively treated and stacked in rare earth (RE) industry. It is of importance to develop some novel processes for separating Th from REs using solvent extraction. The amide group was considered to have good selectivity for Th separation from REs. In order to solve the problem of RE entrainment during Th separation together with primary amine (N1923, (CnH2n+1)2CHNH2 n = 9–11) does not extract Th in hydrochloric acid system, three oxamic acid type extractants have been designed and synthesized in this paper. Among the extractants, the separation performance of 2-(dibenzylamino)-2-oxoacetic acid (DBOA) was indicated to be the best. As for the effective separation, the electron affinity of Th was larger, it was more preferred to coordinate with the extractant. The hydrogen ions released by the extractant could inhibit the extraction of REs rather than Th. Accordingly, Th could be separated from REs. Saponification process of oxamic acid extractant could be omitted in this separation process. By extracting Th using a lower concentration of oxamic acid selectively, not only the loss of RE could be reduced, but also a higher purity of Th could be obtained. Using a simplified fractional extraction experiment, the purity of RE in aqueous phase was increased to be 99.92% or higher, and the purity of obtained Th after stripping from loaded organic phase was increased to be 99.5%.

Use of the Hygrometric Method for Determination of Water Activity of an Aqueous Hydrochloric Acid System at 298.15 K

This paper aims to extend the application field of the hygrometric method to systems containing volatile electrolytes. In this way, the aqueous hydrochloric acid–water solution and the aqueous hydr...

Expired Abacavir Sulfate Drug as Non-toxic Corrosion Inhibitor for Mild Steel (MS) in 3 M Hydrochloric Acid System

The anti-corrosion property of expired Abacavir Sulfate drug on the mild steel (MS) in the 3 M HCl solution was carried out with the help of weight loss, atomic absorption spectroscopy, Tafel plot, impedance spectroscopy, and scanning electron microscopy studies. The weight loss studies show that, protection property enhances with a rise in the amounts of expired Abacavir Sulfate drug and the maximum of protection efficiency observed at 0.4 g/L of expired Abacavir Sulfate drug. The effect of four different amounts of expired Abacavir Sulfate drug on the MS in the 3 M HCl solution was studied by atomic absorption spectroscopy technique. Mixed MS corrosion inhibition property of expired Abacavir Sulfate drug was confirmed by Tafel plot studies. Nyquist plot studies show that, charge transfer resistance (R ct) values are directly proportional to the expired Abacavir Sulfate drug. Scanning electron microscopy results shows that, smooth MS surface in 3 M HCl solution is due to the presence of 0. 4 mg/L of expired Abacavir Sulfate drug.

Synthesis and phase behavior of double sensitive linear amphiphilic prepolymers before gelation

A series of amphiphilic linear prepolymers for gelation, poly(poly(ethylene glycol) diglycidyl ether—monoethanolamine—poly(propylene glycol) diglycidyl ether), i.e. polyPEMPPs, were designed and synthesized by using poly(ethylene glycol) diglycidyl ether (PEGDGE), Poly(propylene glycol) diglycidyl ether (PPGDGE), and monoethanolamine (MEA) as main raw materials through nucleophilic addition/ring-opening reaction. The amphiphilic structure in the backbone of the prepolymers polyPEMPPs causes a phase transition in aqueous solution and has multiple stimuli responsiveness. The effects of hydrogen bonding and electrostatic interactions on phase transition behavior were discussed and analyzed structural reasons in detail. This has important guiding significance for further research on control sol–gel transition. The effects of polyPEMPPs concentration, content of PEGDGE and solution pH values on the phase transition temperature were examined. The experimental results show that increasing polyPEMPPs concentration promotes the phase transition, the transition temperature decreasing with increasing PEGDGE content. In the pH experiment, intra- and intermolecular association became difficult and the phase behavior will be inhibited, whether hydrochloric acid system or sodium hydroxide system. Moreover, we also experimented oscillatory phase transition, and the result exhibited a stably reversible phenomenon transition.

Efficient extraction of bismuth from hydrochloric acid solution by copper powder

An efficient method for extracting bismuth (Bi3+) from a hydrochloric acid (HCl) system by cementation with copper (Cu0) powder was proposed in this work. The thermodynamic properties of cementation were investigated via cyclic voltammetry measurement and thermodynamic calculation. Then, the effects of reaction temperature, Cu0/Bi3+ molar ratio, stirring rate, HCl concentration, and competing ions on the cementation efficiency of bismuth were systematically investigated. Results showed that the cementation reaction between bismuth and copper powder was thermodynamically spontaneous. A Bi recovery of 99% could be achieved with copper powder under an optimized cementation condition (6 mol L−1 HCl, 60 °C, Cu0/Bi3+ molar ratio of 4, stirring rate of 500 rpm, and reaction time of 30 min). Kinetics study revealed that Cu0-Bi3+ cementation followed a first-order reaction law in the range of 20 °C–60 °C. The activation energy of bismuth cementation was 8.58 kJ mol−1. The generated cuprous ions can be recovered as copper sulfides by sulfuration after Bi3+ was extracted. This finding indicated that Cu0 powder cementation showed potential for Bi3+ extraction.

Expired Lorazepam Drug: A Medicinal Compound as Green Corrosion Inhibitor for Mild Steel in Hydrochloric Acid System

The present study explores the green corrosion inhibition property of expired Lorazepam tablet on the mild steel (MS) in 3M HCl solution using gravimetric (mass loss), atomic absorption, Tafel plot, electrochemical impedance, quantum chemical, and scanning electron microscopy (SEM) studies. It is found that; expired Lorazepam tablet shows the robust corrosion inhibition property (protection efficiency = 90%) on the MS at 0.4 g/L of expired Lorazepam drug (observed from the gravimetric studies) at 333 K with a contact time of 3 h. The significant enhancement in the protection performance of the expired Lorazepam tablet has been observed by atomic absorption spectroscopy technique. The results of Tafel plots show that, the presence of the expired Lorazepam tablet of different concentration decreases the both cathodic and anodic processes at MS in the 3M HCl solution by blocking the MS active sites and behave as a mixed mode corrosion inhibitor. Electrochemical impedance studies show that, increase in the amounts of expired Lorazepam tablet increases the charge transfer process at MS-HCl interface. The electron transfer nature of the expired Lorazepam tablet on the MS surface was confirmed from the Quantum chemical studies. The adsorbed invisible layer over the surface of MS was scrutinized by scanning electron microscopy technique.

Theoretical and experimental approach of inhibition effect by sulfamethoxazole on mild steel corrosion in 1‐M HCl

The inhibition effect of sulfamethoxazole on mild steel corrosion in 1‐M hydrochloric acid solution is investigated by electrochemical and quantum chemical measurements. Electrochemical polarization studies show that sulfamethoxazole acts as a mixed‐type corrosion inhibitor. The adsorption of the inhibitor on mild steel in 1‐M hydrochloric acid system is studied at different temperatures (303‐333 K). The adsorption of sulfamethoxazole on mild steel surface is an exothermic process and obeys the Temkin adsorption isotherm. Based on the potential of zero charge values and quantum chemical parameters, the mechanism of adsorption is proposed.

Microwave-assisted Depolymerization of Lignin with Metal Chloride in a Hydrochloric Acid and Formic Acid System

A microwave-assisted depolymerization method of lignin with various metal chloride catalysts (MgCl2, AlCl3, FeCl3, ZnCl2, and MnCl2) in a formic acid and hydrochloric acid system under mild conditions (160 °C for 30 min) was studied. The resulting bio-oil was identified by a gas chromatography-mass spectrometer, and the solid residue was analyzed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, the molecular weight change of lignin after the reaction was measured by gel permeation chromatography. The MnCl2 catalyzed lignin to produce most aromatic monomers, including approximately 23.0% G-type, 11.9% S-type, and 14.8% H-type monomer compounds. Different metal chloride catalysts had different effects on the depolymerization of lignin, which were embodied in the type and content of the products. It was also worth noting that the catalytic effects of transition metal chlorides on lignin may have been related to each chloride’s cation radius.