Concentrated Hydrochloric Acid Solution Research Articles

Separation of platinum(IV) and palladium(II) from concentrated hydrochloric acid solutions by mixtures of amines with neutral extractants

Separation of platinum and palladium from concentrated HCl solutions by extraction with mixture of amines (Aliquat 336/Alamine 336/TOA) and neutral extractants (TBP/TOP/MIBK) have been investigated. The mixture of Aliquat 336 and TBP led to higher Pt(IV) separation factor at 6M HCl solution. McCabe–Thiele diagram for the extraction of Pt by this mixture was constructed. Low concentration of thiourea in the HCl solution resulted in selective stripping of Pd from the loaded organic. Pt solution with 99.9% purity was obtained by extraction and stripping from the solution containing Pd. A process was proposed to separate the two metals.

A Review of Texture Related Corrosion of Thin Metallic Films

Most of electrochemical properties of thin materials are closely related with the microstructure of the thin films. In this paper, we review the preferred orientation dependency of metals in aqueous solutions. For example, aluminum foil etching in highly concentrated hydrochloric acid solution, etching of invar sheet for shadow masks, and texture related stress corrosion cracking of metals and alloys are discussed. All the phenomena were interpreted in terms of elastic properties of thin films and bulk materials. Keywords: Aluminum, corrosion, etching, invar, stress corrosion cracking, texture, thin film.

Indium Recovery by Selective Removal of Copper and Tin from ITO Etching Waste Solution by Cementation with Cobalt and Subsequent Electro-Winning: A Validation Experiment

AbstractA three-step batch-type indium recovery method was developed to prove feasibility of recovering indium powders from highly acidic dilute indium chloride solution prepared by dissolving indium tin oxide (ITO) electrodes of waste liquid crystal display (LCD) panels in concentrated hydrochloric acid (HCl) solutions. More specifically, a batch-type three-step indium recovery by cementation and subsequent electro co-deposition process was designed and performed and its individual experimental parameters were varied to get insights in the engineering feasibility of validation experiments. Significant proportion of copper and tin was removed by cementation with cobalt powder. Residual copper and tin ions were further removed by primary electro co-deposition directly from the highly acidic etching waste solution recovered from cementation process. Synergistic effect of cobalt electro co-position on indium electro-reduction was observed during secondary electro co-deposition, which warrants additional electro-refining process for selective removal of indium from cobalt-indium metal mixture and its purification. Ionic and metallic species thus obtained from the validation experiments were further characterized using various analytical tools such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), and X-ray fluorescence (XRF).

Recovery of indium powders from indium chloride solutions by cementation

A three-step, batch type recovery method was developed to produce indium powders from dilute indium chloride solutions prepared by dissolving indium tin oxide (ITO) electrodes from waste liquid crystal display (LCD) panels in concentrated hydrochloric acid (HCl) solutions. A 5–L batch process was used with individual experimental parameters for cementation, such as temperature and time, which were varied to optimise their effects on the physicochemical properties and purity of the recovered indium powders and the recovery rate. A validation experiment was performed by preparing indium bearing solutions in a 5–180 min kinetic study of indium cementation with aluminium in aqueous HCl solutions at 65°C. The indium powders obtained from the cementation processes were further characterised using various analytical tools, such as ICP/AES, X-ray diffraction (XRD), and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS). Cementation at 60°C for 10 min resulted in the optimal process efficiency, with a recovery rate and indium purity of 70 and 99·8% respectively. On a développé une méthode de récupération discontinue à trois étapes afin de produire des poudres d'indium à partir de solutions diluées de chlorure d'indium préparées en dissolvant des électrodes d'oxyde d'indium et d'étain (ITO), provenant de panneaux d'affichage à cristaux liquides (LCD) de rebut, dans des solutions concentrées d'acide chlorhydrique (HCl). On a utilisé un procédé discontinu de 5 L avec paramètres expérimentaux individuels de cémentation, comme la température et la durée, que l'on variait afin d'optimiser leurs effets sur les propriétés physicochimiques et la pureté des poudres d'indium récupérées et sur le taux de récupération. On a effectué une expérience de validation en préparant des solutions porteuses d'indium dans une étude cinétique de 5 à 180 min de cémentation de l'indium avec de l'aluminium, dans des solutions aqueuses d'HCl à 65°C. On a ensuite caractérisé les poudres d'indium obtenues à partir des procédés de cémentation en utilisant divers outils analytiques, comme l'ICP/AES, la diffraction des rayons X (XRD), et la microscope électronique à balayage—spectroscopie à dispersion d'énergie (SEM-EDS). On a obtenu le rendement optimal du procédé par cémentation à 60°C pendant 10 min, avec un taux de récupération et une pureté de l'indium de 70 et 99·8%, respectivement.

Indium ion cementation onto aluminum plates in hydrochloric acid solutions: a kinetic perspective

Abstract The cementation of indium on an aluminum plate in indium-bearing concentrated hydrochloric acid solutions has been performed over a period of 2 hr at 278, 298, 318, 328 and 338 K. Aluminum was selected for two reasons: (1) aluminum has significantly higher oxidation potential compared to indium and (2) the leaching of waste plasma display panels produces a significant concentration of aluminum ions in solution. The effect of the cementation variables was comprehensively investigated, and a preliminary kinetic analysis was made using first order kinetics with pertinent Arrhenius-type plots. The cementation process was highly temperature sensitive for the range of 298–338 K, and more than 96% of the indium was recovered at 338 K. For morphology and purity analysis, indium powders obtained from the cementation process were examined using various analytical tools, such as X-ray diffraction and scanning electron microscopy–energy dispersive X-ray spectrometry.

Dissolution of metal oxides in an acid-saturated ionic liquid solution and investigation of the back-extraction behaviour to the aqueous phase

The dissolution of metal oxides in an acid-saturated ionic liquid, followed by selective stripping of the dissolved metal ions to an aqueous phase is proposed as a new ionometallurgical approach for the processing of metals in ionic liquids. The hydrophobic ionic liquid trihexyl(tetradecyl)phosphonium chloride (Cyphos IL 101) saturated with a concentrated aqueous hydrochloric acid solution was used to dissolve CaO, NiO, MnO, CoO, CuO, ZnO and Fe2O3. It was found that nickel(II) and calcium(II) could be separated from all other transition metals present in the ionic liquid phase by stripping at high chloride concentrations. By scrubbing the ionic liquid solutions phase with water, manganese(II) and cobalt(II) could be stripped together with a fraction of iron(III) and copper(II), leaving zinc(II) and the remainder of copper(II) and iron(III) in the ionic liquid phase. These metal ions could be removed from the ionic liquid using ammonia. Copper(II) and zinc(II) formed ammine complexes and were back-extracted, while iron(III) precipitated as iron(III) hydroxide. After removal of all the metals present in the ionic liquid phase, the ionic liquid was prepared for reuse. Unfortunately, the mutual separations nickel–calcium, cobalt–manganese, or zinc–copper could not be achieved. This system would be useful when nickel is the metal of interest, since separation of nickel from all other transition metals present in the solution is achieved by one stripping step.

Adsorption Behavior of Neptunium Ions on Pyridine-type Resin in Hydrochloric Acid Solutions

The adsorption behavior of neptunium ions on the synthesized pyridine-type resin (Abbreviated as PYAER) in hydrochloric acid solutions whose concentrations are in the 0.10-11.5 M region has been studied at room temperature. Neptunium has many kinds of valence states of ions; mainly tetravalent, pentavalent, and heptavalent ions. We have controlled the neptunium valence states by using redox reactions and confirmed the valence states in hydrochloric acid solutions using an ultraviolet visible nearinfrared absorption photospectrometry at room temperature before the adsorption experiments described above. After adjusting the valence states of neptunium ions, the adsorption mechanisms on the neptunium ions with PYAER was studied by batch-wise adsorption experiments and the estimated mechanisms were compared with those of heptavalent uranium, trivalent lanthanides, and tetravalent plutonium against PYAER. As a result, it was found that the obtained distribution coefficients (Abbreviated as Kd) of neptunium with PYAER increase with increasing of the concentrations of hydrochloric acid solutions and their order was heptavalent > tetravalent ≒ pentavalent. The Kd values of tetravalent plutonium were found to be between the Kd values of neptunium. On the other hand, it was also revealed that trivalent lanthanides show little adsorption ability for PYAER in the examined hydrochloric acid concentration ranges and PYAER was able to adsorb strongly heptavalent uranium ions with increasing concentrations of hydrochloric acid. In brief, the obtained Kd values increased in order of lanthanides, neptunium (≒ plutonium), and uranium. These results support the positive possibility of the mutual separation of uranium, plutonium containing neptunium, minor actinides (Am, Cm), and lanthanides and were therefore found to be valuable data for our proposed reprocessing process.

Effect of Dual-Phase Treatment on the Corrosion Behavior of Weathering Steel 09CuPCrNi

Dual-phase steels of 09CuPCrNi are prepared through intercritical quenching process. The influences of dual-phase treatment on the corrosion resistant property of the steels have been studied by electrochemical potentiodynamic tests and artificial salt spray tests. The results indicate that the corrosion behavior of DP780 and the as-received weathering steel in 5% sodium hydroxide, 3.5% sodium chloride, 5% sulphuric acid and various concentrations of hydrochloric acid solutions are identical, but dual-phase steels show least corrosion current as compared to the as-received steel. Rust layers of the as-received steel and DP780 are identical mainly consisting of three iron (hydr) oxides, goethite, akaganeite and lepidocrocite, and magnetite. Both the relative amount and morphology of phase constituents affect on the corrosion behavior of DP steels.

Inner-Sphere Structure of Rhodium Complexes with Tin(II) Chloride in Concentrated Hydrochloric Acid Solution

Abstract The coordination properties of highly concentrated rhodium complexes (Rh: ca. 10 g L−1) in concentrated hydrochloric acid solution upon addition of tin(II) chloride were investigated using Rh and Sn K-edge XAFS spectra. For Rh solutions in the absence of Sn, the Rh ion shows no inner-sphere H2O complexation for [HCl] ≥ 6 M. The coordination structure of Rh in 3 M HCl solution (ca. 1 O(H2O) at 2.06(3) Å and ca. 5 Cl− at 2.321(8) Å) drastically changes with increasing amount of tin(II) chloride added; the Sn directly coordinates to Rh by replacing the H2O/Cl−. At [Sn]/[Rh] = 12.4, the inner coordination sphere of Rh is occupied only by Sn (ca. 5 Sn at 2.510(7) Å). The curve fits of the Sn K-edge EXAFS spectra for the Rh–Sn system show that the Sn has ca. 3 Cl− and ca. 1 Rh in the inner coordination sphere. XANES analysis reveals that the Rh ion is reduced from trivalent to monovalent with concomitant oxidation of the Sn ion, divalent to tetravalent. These results demonstrate that the Rh complexes in 3 M HCl solution transform from [RhIIICl5(H2O)]2− to [RhI(SnIICl3)5]4− through the [RhIIICln(H2O)m(SnIICl3)6−n−m]n−3 complex (1 ≤ n ≤ 5, 0 ≤ m ≤ 1) with an increase in the Sn concentration.

Inhibitory Action of 1–phenyl–3–methylpyrazol–5–one (HPMP) and 1–phenyl–3–methyl–4–(p–nitrobenzoyl)– pyrazol–5–one (HPMNP) on the Corrosion of Alpha and Beta Brass in HCl Solution

The inhibition of corrosion of Alpha - Brass (70% Cu, 30% Zn) coupons and Beta - Brass (60% Cu, 40% Zn) coupons in different concentrations of Hydrochloric acid solution (HCl) at room temperature by 1-phenyl-3- methylpyrazol- 5- one (HPMP) and 1-phenyl-3-methyl-4-(p-Nitrobenzoyl)-pyrazol-5-one (HPMNP) was investigated, using weight loss technique. Generally, inhibition was found to increase with increasing inhibitor concentration. HPMNP inhibited the two Brasses better than HPMP, and Beta - Brass (60% Cu, 40% Zn) corroded faster than Alpha - Brass ( 70% Cu, 30% Zn ). The inhibition was assumed to occur via adsorption of the inhibitor molecules on the metal surface. The effect of immersion time was also carefully followed to study the corrosion and inhibition phenomenon.

Effect of Replacement of Cement by Metakalion on the Properties of High Performance Concrete Subjected to Acid Attack

This paper presents an experimental investigation on the effect of partial replacement of cement by metakalion by various percentages viz 0%, 10%, 20%, and 30% on the properties of high performance concrete, when it is subjected to hydrochloric acid attack. An aggregate binder ratio of 2 and different water binder ratios viz 0.3, 0.35, 0.40 and 0.45 was used in this investigation. Concrete specimens of size 150 x 150 x 150 mm were casted to find residual compressive strength and specimens of size 100 x 100 x 100mm were casted to find percentage weight loss; both the sizes of specimens were casted and cured as per IS specification. After 28 days water curing, the concrete specimens were kept immersed in 5% concentrated hydrochloric acid solution for 30, 60 and 90 days for observation. Before immersion, they were weighed accurately and after required days of immersion and observation, the specimens were removed from hydrochloric acid media, weighed accurately and tested for their compressive strength; weight loss and hardness of concrete were studied. The various results which indicate the effect of replacement of cement by metakalion on HPC are presented in this paper to draw useful conclusions. The results were compared with reference mix. Test results indicate that use of replacement cement by metakalion in HPC has improved performance of concrete up to 10%

Dibromo and diiodo derivatives of [4.4]dibenzo-24-crown-8 as novel efficient sorbents of elements from mineral acid solutions

The sorption behavior of novel functionalized endoreceptors, halogen (Br, I) derivatives of [4.4]dibenzo-24-crown-8, with respect to sorption of 34 elements from 1–5 M HNO3 solurions and 29 elements from 1–5 M HCl solutions were studied. The receptors poorly extract elements from nitric acid solutions but are strong sorbents of some elements from concentrated hydrochloric acid solutions. The highest distribution ratios of elements (D, cm3/g) for sorption from 5 M HCl were observed for 4′,4″,5″[4.4]dibromodibenzo-24-crown-8: Au (D = 880) > Ga (469) > Sb (70) > Fe (55) > Sn (14.3) > Mo (10.3) > Re (2.9) > Cd (1.4) > Ge (0.61) > In (0.33) ≈ Zn (0.32) ≈ Ni (0.31) > Zr (0.29) ≈ Cr (0.28) > Sr, Tl (0.25) > Be (0.24) > Mn (0.22) ≈ La (0.21) ≈ Ba (0.20) > Ca, K, Mg, Si (< 0.1). A new way for increasing the sorption properties of dibenzocrown ethers by introducing bromine substituents into the polyether benzene rings was established. The sorption of elements from concentrated hydrochloric acid solutions follows an anion exchange mechanism by analogy with extraction of these elements.

Recovery of Copper and Cobalt from Spent Aerospace Material with Pollution-Free Oxidant

The acid leaching of spent aerospace material with pollution-free oxidation is discussed. Effect of parameters including initial concentration of hydrochloric acid solution, leaching temperature, reaction time, agitation speed, liquid to solid ratio and concentration of oxidant on valuable element extractions are determined, the optimized conditions are 6 M, 60 °C, 30 min, 250 r/min, 6:1 and 0.0378 mol•L-1•min-1, respectively. The comprehensive results of experiments show that the extracting efficiency of Co and Cu are over 83% and 98% respectively when optimized conditions were adopted.

Synthesis of hydrochloric acid solution for total mercury determination in natural waters

Total mercury (Hg(T)) determination requires the addition of concentrated hydrochloric acid solution (≥10 mol L(-1) HCl) in relatively high amounts to preserve the samples and to prepare reagent solutions. A method for the preparation of concentrated HCl with Hg(T) concentration of lower than 5 ng L(-1) is described in this article. It is based on the well-known chemical reaction: 2 NH(4)Cl + H(2)SO(4) → (NH(4))(2)SO(4) + 2 HCl. This method is validated thanks to the US Environmental Protection Agency method 1631 and standard reference materials BCR-579 (mercury in coastal seawater).

Enhancement of resolution and quality of nano-hole structure on GaN substrates using the second-harmonic beam of near-infrared femtosecond laser

By using a second harmonic of near infrared femtosecond (fs) laser (λ=387 nm, 150 fs) with high NA objective lens, fabrication resolution has been greatly improved in nano-fabrication of wide band-gap semiconductor gallium nitride (GaN). We have carried out a wet-chemical-assisted fs laser ablation method, in which the laser beam is focused onto a single-crystal GaN substrate immersed in a concentrated hydrochloric (HCl) acid solution. A two-step processing involving irradiation with a fs laser beam in air followed by wet chemical treatment is also performed for comparison. In the wet-chemical-assisted ablation, theoretical diameters of ablation craters are calculated as a function of pulse energy by assuming that the reaction is based on two-photon absorption. In lower energy, the calculated curve is close to the experimental value, while the actual measured diameters in the region of higher energy are larger than calculated values. In the condition of the highest fabrication resolution, we obtained ablation craters smaller than 200 nm at full width at half maximum. We have also demonstrated the fabrication of two-dimensional (2D) periodic nanostructures on surface of a GaN substrate using the second harmonic single fs-laser pulse. Uniform ablation craters with the size as small as 410 nm in diameter are arranged with a periodicity of 1 μm. Such structures are applicable to 2D photonic crystals which improve the light extraction efficiency for blue LEDs in the near future.

Influence of hydrochloric acid concentration on the demineralization of cortical bone

Although demineralized bone matrix has been considered a successful grafting material, combining both osteoconductive and osteoinductive properties, conflicting results have been published in the literature regarding its bone-inducing abilities. This may be a consequence of following different demineralization procedures that naturally result in products with different properties. The present work examines the evaluation of the demineralization process of similar samples of human cortical bone using three different concentrations of hydrochloric acid solutions (0.6 M, 1.2 M and 2.4 M). Sample calcium content was determined (by Atomic Absorption Spectroscopy) at various immersion times, allowing the construction of the corresponding kinetic profiles. Phase and chemical composition were enabled by X-Ray Diffraction Spectroscopy and Fourier Transform Infrared Analysis, respectively. Structural modifications were followed by Light and Scanning Electron Microscopy and quantified by mercury porosimetry (in terms of porosity and pore size distribution). As expected, increasing the acid concentration led to an increase in the demineralization rate, but not in a proportional way. However, one of the most significant effects of the acid concentration was found on the sample structural features. In fact, a considerable increment in porosity was detected for the sample subjected to the highest hydrochloric acid concentration. Microscopic observations demonstrated that despite the structural deformation resultant from demineralization, the basic microstructure was preserved.

Microstructure and Far Infrared Emission Properties of Tourmaline Powders Eroded by Hydrochloric Acid

The microstructure and far infrared emission properties of tourmaline powders eroded by hydrochloric acid were investigated. The indexes including crystal structure, unit cell volume, microstructure and infrared spectra were characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results show that the crystal structure was not changed; however, the unit cell volume decreased, the angularities of tourmaline particles became smooth, and there appeared nanohollows on their surfaces. The infrared emission properties were enhanced at proper concentrations of hydrochloric acid solutions.

Extraction of niobium from hydrochloric solutions with tertiary amines in aprotic diluents

Extractive recovery of niobium from concentrated hydrochloric acid solutions with tertiary amines in alkylbenzene diluents in the absence of modifiers was studied.

Effects of minor additions of ruthenium on the passivation of duplex stainless-steel corrosion in concentrated hydrochloric acid solutions

The effects of minor additions of ruthenium (0.14%, 0.22%, and 0.28%) on the passivation of duplex stainless-steel (DSS, Fe–22%Cr–9%Ni–3%Mo) corrosion in 2 M HCl solutions have been studied using open-circuit potential (OCP), potentiodynamic cyclic polarization, potentiostatic current–time, electrochemical impedance spectroscopy (EIS), and weight loss measurements. OCP measurements showed an increased shift in the corrosion potential to more positive values with increasing Ru content. Polarization and EIS experiments indicated that the presence of Ru and the increase of its content decrease the corrosion rate, critical and passive current density, and polarization resistance. Moreover, it shifts the corrosion and pitting potentials to more positive values. Current–time measurements at −100, −50, and 50 mV versus Ag/AgCl also confirmed that the severity of pitting corrosion decreases with an increasing Ru content. Weight-loss time data showed good agreement with the electrochemical measurements.

Synthesis and characterization of mesoporous SiO2 by the chemical precipitation method

Mesoporous silicon dioxide (SiO2) powders with different specific surface areas were prepared by the chemical precipitation method from sodium metasilicate, hydrochloric acid, and cetyl trimethylammonium bromide (CTAB). The obtained samples were characterized by the BET method — differential scanning calorimetry/thermogravimetry (DSC/TG), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM). The effects of some factors, such as pH, concentration of sodium metasilicate, concentration of hydrochloric acid solution, and reaction temperature, on the specific surface area were investigated. Mesoporous SiO2 with a BET-specific surface area of 1041.382/g and an average pore size of 5.78nm was made under the following conditions: pH, 8; concentration of sodium metasilicate, 0.4mol/L; concentration of hydrochloric acid, 1.0mol/L; reaction temperature, 30°C.