Aqueous Hydrochloric Solutions Research Articles

Complexation of ThoriumIV with Fluorinated Heterocyclic β‐Diketones in Aqueous Hydrochloric Solutions

AbstractThe interaction of Thorium(IV) with a group of non‐symmetric CF3‐diketones has been studied by means of electronic absorption spectroscopy in HCl aqueous solutions at I=0.5 M (NaCl) and T=298 K. Six heterocyclic dicarbonyl ligands (2‐thenoyl‐trifluoroacetone, 2‐furoyl‐trifluoroacetone, 2‐selenophen‐trifluoroacetone, 2‐tellurophen‐trifluoroacetone, phenyl‐trifluoroacetone, and 2‐naphthyl‐trifluoroacetone) demonstrate the chelation activity toward ThIV in the acidic pH range. Obtained values of the “true” stability constants lie in the range 6.2–6.8 logarithmic units, respectively. A significant (10–15 nm) bathochromic shift between the maximum absorption wavelength of lanthanide and actinide monocomplexes has been detected. Observed spectral shift increases with the atomic number of substituted chalcogen atoms in the heterocyclic ring of the corresponding ligand: 10 nm for furan, 11 nm for thiophen, 14 nm for selenophen, and 15 nm for tellurophene rings. The complexation with Thorium occurs in an acidic media, where studied ligands do not interact with transition and rare earth metals. Spectral and pH shifts make studied ligands useful reagents for the detection and analytical determination of Thorium in the mixture with other metals without prior separation. Quantum‐chemical simulations (DFT and TD‐DFT) demonstrate that the nine‐ and deco‐coordinated structures of ThoriumIV complexes reproduce experimental values within reasonable errors.

Effect of Mo content on microstructure and corrosion behavior in HCl of ultra-high strength maraging steels

Maraging steels are one of the highest strength steels commercially available. The new versions are known as ultra-high strength maraging (UHSM) steels and can offer yield strength values over 3 GPa. The aim of this investigation was evaluating the electrochemical behavior of three non-commercial/laboratory UHSM steels containing 13Ni–15Co and Mo content variations (7.5, 11 and 15 wt%). The UHSM steels were annealed at 1000 °C and studied at different conditions (non-aged and aged at 480 °C for 3 h and 6 h). As reference material, a commercial maraging steel (18Ni–9Co–5Mo) heat treated according to typical recommendations (annealed at 820 °C for 1 h and aged at 480 °C for 4 h) was used. The UHSM presented considerable higher hardness than commercial maraging. Comparing between the UHSM steels, the samples treated for 6 h do not contribute to increase the hardness when compared to those of 3 h. The electrochemical tests in hydrochloric aqueous solution showed that commercial maraging steel and the UHSM containing most Mo (11 wt%) aged by 6 h presented the worst corrosion resistance while the best performance was obtained by the samples with 7.5 and 11 wt% Mo aged for 3 h.

Enhanced corrosion inhibition of copper in acidic environment by cathodic control of interface formation with 2-mercaptobenzothiazole

Electrochemistry along with advanced surface analyzes (X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry) were implemented to investigate copper corrosion inhibition by 2-mercaptobenzothiazole (2-MBT) in hydrochloric aqueous solution and the effects of electrochemical control on the formation of the inhibiting interface. It is shown that reducing the native surface oxide by cathodic reduction prior to exposure to the inhibitor drastically decreases the rate of anodic dissolution. Additionally, increasing the exposure time of the metal surface to the inhibitor results in even better protection against dissolution. 2-MBT adsorbs as multilayers and bonds to both metallic copper and residual copper oxide islands via its sulphur atoms. Partial dissociation of the molecule, releasing the exocyclic sulphur, which then bonds to metallic Cu, is observed. Further dissociation of the molecule, releasing the endocyclic sulphur, is induced by anodic polarization, forming defects in the organic layer and thus compromising the barrier properties of the organic layer.

Castor oil based high transparent UV cured silicone modified polyurethane acrylate coatings with outstanding tensile strength and good chemical resistance

Castor oil based high transparent silicone modified UV cured polyurethane acrylate coatings with outstanding tensile strength and good chemical resistance were developed with castor oil based polyurethane acrylates and thiol silicone resin. The UV cured coatings are with transparency in range of 90–98%, tensile strength as high as 10.2 MPa and elongation at break in the range of 88.4–162.5%. It is worth noting that the tensile strength of the coatings immersed in 3.5 wt% hydrochloric aqueous solution 144 h increased from 6.2 MPa to 15.5 MPa while the elongation at break is almost not changed, which reveals that the UV cured coatings also exhibit good chemical anti–corrosion performance. The UV cured coatings also show quite good UV resistance and adhesive properties.

Corrosion effects on the nanotribology of a Ni62Nb38 metallic glass

The onset of corrosion in 0.1 M nitric and hydrochloric aqueous solutions and its effect on the friction and wear of a Ni62Nb38 MG have been investigated by AFM, XPS and SEM. Depending on the acidic solutions, the properties of the oxide layers grown on Ni62Nb38 MG differ, which affects the tribological response of the surface. A clear transition from shearing to ploughing friction is observed for as-spun Ni62Nb38. After etching in nitric acid, the onset of ploughing is retarded, and wear is reduced. In contrast, ploughing is suppressed after immersion in HCl. In that case friction and wear are dominated by adhesion and material transfer.

Au3Cu nanosquares and frames for glucose sensor and CO oxidation catalyst

Au–Cu bimetallic nanomaterials have attracted tremendous attention in the field of catalysis, water splitting, biosensor and biotherapy. Au3Cu nanocrystals with a definite stoichiometric ratio and ordered arrangement of atoms have shown great potential for efficient catalyts. Herein, we reported a new method for fabrication of Au3Cu nanocrystals. Their morphologies can be tuned by the amount of hydrochloric aqueous solution, including nanosquare and frame were achieved, respectively. The as-synthesized Au3Cu nanosquares not only demonstrated a comparatively high sensitivity of 324.8 μA mM−1 cm−2 as a non-enzymatic glucose sensor but also performed well in CO catalytic oxidation even at 50 °C with a conversion efficiency of 30 mmol g−1 h−1.

Interaction of Pt(II) and Au(III) with organic disulfides in hydrochloric aqueous solution

The interaction of Pt(II) and Au(III) with disulfides (l-cystine, cystamine, dl-homocystine and 3,3′-dithiodipropionic acid) in hydrochloric acid aqueous solutions was studied. In the case of Pt(II), the oxidative addition reaction leads to formation of the Pt(IV) thiol complex. In the case of Au(III) disulfide, binding causes a reduction to Au(0) and oxidation of the disulfide to sulfonic acid. Cyclic voltammetry and different spectroscopic methods were used to study the process. The pattern of influence of the metallic properties for d8 ions in the direction of the reaction was found.

Reactions of dl-homocystine and 3,3′-dithiodipropionic acid with Pd(II) in aqueous hydrochloric solutions. Part II: Kinetics and mechanistic investigations

Kinetics and mechanisms of a disulfide bond disproportionation in dl-homocystine (H2HCysS) and 3,3′-dithiodipropionic acid (H2DTDPA) induced by Pd(II) species were investigated spectrophotometrically in strong hydrochloric acidic media. The products of the disproportionation are thiolate and sulfinate complexes. The reaction of Pd(II) with H2DTDPA is autocatalytic with contributions from both catalytic and non-catalytic pathways. The reaction of Pd(II) with H2HCysS is irreversible and of the first order. For both ligands, a rate-determining step is the formation of a S,S′-binuclear complex species prior to the disproportionation. A subsequent electrophile-assisted disproportionation of a disulfide bond is caused by a nucleophilic attack of a water molecule. Both reactions proceed through an associative mechanism by a solvolytic pathway. The difference in the mechanisms for two ligands is explained in terms of steric availability of a disulfide bond.

Reactions of dl-homocystine and 3,3′-dithiodipropionic acid with Pd(II) in aqueous hydrochloric solutions. Part I: coordination model

Stoichiometry of Pd(II) interactions with dl-homocystine and 3,3′-dithiodipropionic acid were investigated spectrophotometrically in strong hydrochloric acidic media. It was established that thiolate and sulfinate complexes are products of a disulfide bond cleavage. It is shown that formation of S,S′-binuclear complexes is necessary for the disproportionation reaction. A multi-spectroscopic (UV-Vis, Raman, NMR, EXAFS) investigation on a disulfide bond state in organic disulfides in complexation processes with Pd(II) was developed. A DFT study on geometry of forming complex species was performed.

A Rapid Dialysis Method for Analysis of Artificial Sweeteners in Foods (2nd Report).

Following the previous report, a rapid dialysis method was developed for the extraction and purification of four artificial sweeteners, namely, sodium saccharide (Sa), acesulfame potassium (AK), aspartame (APM), and dulcin (Du), which are present in various foods. The method was evaluated by the addition of 0.02 g/kg of these sweeteners to a cookie sample, in the same manner as in the previous report. Revisions from the previous method were: reduction of the total dialysis volume from 200 to 100 mL, change of tube length from 55 to 50 cm, change of dialysate from 0.01 mol/L hydrochloric aqueous solution containing 10% sodium chloride to 30% methanol solution, and change of dialysis conditions from ambient temperature with occasional shaking to 50℃ with shaking at 160 rpm. As a result of these revisions, the recovery reached 99.3-103.8% with one hour dialysis. The obtained recovery yields were comparable to the recovery yields in the previous method with four hour dialysis.

Manufacturing conductive polyaniline/graphite nanocomposites with spent battery powder (SBP) for energy storage: A potential approach for sustainable waste management

A potential approach for sustainable waste management of the spent battery material (SBM) is established for manufacturing conductive polyaniline (PANI) nanocomposites as electrode materials for supercapacitors, following the principle of “What comes from the power should be used for the power”. The ternary nanocomposites (G/MnO2/PANI) containing PANI, graphite powder (G) and remanent MnO2 nanoparticles and the binary nanocomposites of polyaniline and graphite powder (G/PANI) are synthesized by the chemical oxidative polymerization of aniline in hydrochloric aqueous solution with the MnO2 nanoparticles in the spent battery powder (SBP) as oxidant. The G/PANI sample, which was prepared with MnO2/aniline mole ratio of 1:1 with 1.0mL aniline in 50mL of 1.0molL−1 HCl, exhibits the electrical conductivity of 22.22Scm−1, the highest specific capacitance up to 317Fg−1 and the highest energy density of 31.0 Wh kg−1, with retention of as high as 84.6% of its initial capacitance after 1000 cycles, indicating good cyclic stability.

Coordination model, stability constant, and kinetics study of cystamine and l-cystine with [PdCl4]2− in hydrochloric aqueous solutions

Stoichiometry, equilibria, and kinetics of [PdCl4]2−interactions with l-cystine (H4CysS2+) and cystamine (H2Cyst2+) have been investigated spectrophotometrically in strong hydrochloric acidic media. Interactions lead to the formation of highly stable S/(S,N)-coordinated binuclear, and then with excess [PdCl4]2− trinuclear (S,S,N) or tetranuclear (S,S,N,N) species without disulfide bond cleavage. The reaction of [PdCl4]2− with H4CysS2+ or H2Cyst2+ at [PdCl4]2− excess has irreversible first-order kinetics, and with H4CysS2+ or H2Cyst2+ excess, by irreversible parallel reaction of [PdCl4]2− addition to the ligand. The influence of leaving groups on the kinetics has been explained in terms of formation of stable ionic pairs with complex species and of efficient overlap of d and π orbitals in a transition state. The reactions proceed through an associative mechanism with the first step being formation of the S-coordinated complex. Coordination models and mechanisms have been proposed. Applicability of spectrophotometry for establishment of disulfide bond state in organic disulfides in complexation processes has been demonstrated.

Сорбционное извлечение палладия углеродными сорбентами из водных растворов

Carbon sorbents from aspen-wood charcoal, mixed birch wood and aspen wood wastes and Siberian larch bark have been produced by pyrolysis and air-steam activation. Results of study of palladium adsorption from aqueous hydrochloric solutions at a concentration of 50-1100 mg/l by obtained active carbons are presented. The degree of palladium isolation was 95-99% at initial palladium concentration below 500 mg/l and consumption of sorbents 10 kg/m 3 .

Crystal structure of the new hybrid material bis-(1,4-diazo-niabi-cyclo-[2.2.2]octa-ne) di-μ-chlorido-bis-[tetra-chlorido-bis-muthate(III)] dihydrate.

The title compound bis-(1,4-diazo-niabi-cyclo-[2.2.2]octa-ne) di-μ-chlorido-bis-[tetra-chlorido-bis-muthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was ob-tain-ed by slow evaporation at room temperature of a hydro-chloric aqueous solution (pH = 1) containing bis-muth(III) nitrate and 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10](4-) bi-octa-hedra (site symmetry -1) separated by layers of organic 1,4-diazo-niabi-cyclo-[2.2.2]octane dications [(DABCOH2)(2+)] and water mol-ecules. O-H⋯Cl, N-H⋯O and N-H⋯Cl hydrogen bonds lead to additional cohesion of the structure.

A thermodynamic and kinetic study on [PdCl4]2– complex formation with L-cystine

Complex formation of with L-cystine (H2CysS) has been studied in hydrochloric aqueous solutions (0.05–1 mol L−1 HCl) by UV-Vis spectroscopy combined with quantum chemical calculations. Our data suggest that L-cystine acts as a monodentate S-coordinating ligand in highly acidic solutions and no evidence of S–S bond fission was found to occur under the experimental conditions. Thermodynamic parameters for Pd(H4CysS) formation were determined: the monocomplex stability constant log K 1 = 3.3 (298 K), ΔH = −27 kJ mol−1, and ΔS = −29 JK−1 mol−1 (0.5 mol L−1 HCl). The experimental reaction rate law has been obtained: W = k[H4CysS2+][][Cl−]−0.86 and the values for the activation parameters have been determined: E a = 66 kJ mol−1, ΔH 1 = 63 kJ mol−1, and ΔS 1 = −77 JK−1 mol−1. The electronic absorption spectra (EAS) of the Pd(H4CysS) complex were computed using time-dependent density functional theory and the polarizable continuum model. The def2-TZVPP basis set (PBE0 and TPSS density functionals) provides good agreement between the experimental and theoretical EAS.

Electrochemical characterization of Zr-based thin film metallic glass in hydrochloric aqueous solution

Recently thin film metallic glass represents a class of promising engineering materials for structural applications. In this work, the Zr-based thin film metallic glass (TFMG) was fabricated on the Si and AISI 420 substrates using a Zr–Cu–Ni–Al alloy and pure Zr metal targets by a pulsed DC magnetron sputtering system. The chemical compositions, crystalline structures, microstructures and corrosion behavior in hydrochloric (HCl) aqueous solutions of Zr-based TFMGs were investigated. The results showed that the surface morphologies of Zr-based TFMG were very smooth. A compact and dense structure without columnar structure was observed. The amorphous structure of Zr-based TFMG was characterized by the X-ray diffractometer and transmission electron microscopy analyses. After the potentiodynamic polarization test, the better corrosion resistance was achieved for the Zr-based TFMG coated AISI 420 in 1mM HCl aqueous solution. Based on the surface morphologies and chemical analysis results of the corroded surfaces, the pitting, crevice corrosion and filiform corrosion were found. The corrosion mechanisms of the Zr-based TFMG were discussed in this work.

Utilization Biomass from Bagasse Ash for Phillipsite Zeolite Synthesis

Bagasse ash is one of the agricultural wastes and valuable biomass by-products in sugar milling. It was treated hydrothermally with hydrochloric aqueous solution at 100 °C and burned at 600°C for 2 hours under oxygen feeding. The obtained white ash was further used as natural silica source instead of silica sol because of highly silica content from an abundant supply of sugar industries in Thailand. Aluminosilicate precursor gel was prepared from alumina source and silica source via sodium silicate preparation. Different crystallization time was studied for the molar ratio of SiO2/Al2O3 = 2 at 100°C crystallization temperature. The phillipsite zeolite synthesized was characterized using various techniques; X-ray diffraction, Scanning electron microscopy, Fourier Transform Infrared Spectroscopy, and BET-N2 adsorption method. The results can be used as value added for bagasse ash utilization, minimize the environmental impact of disposal problems and further application for heavy metal removal.

Effect of dioctyl sulfide on the kinetics of oxidative dissolution of gold nanoparticles in triton N-42 reverse micelles

The effect of additions of hydrophobic dioctyl sulfide (L) on the kinetics of dissolution of gold nanoparticles in the interaction with a dispersed aqueous hydrochloric solution of H2O2 in Triton N-42 reverse micelles (decane was the dispersion medium) was studied spectrophotometrically. The process consists of a two-stage oxidation Au0 → AuCl2− → AuCl4− at the surface of gold particles; the first stage occurs in two ways: a spontaneous reaction and an autocatalytic reaction involving AuCl4− ions. With small additions of L (cL < cAu), only spontaneous oxidation of Au(0) to Au(I) takes place because Au(I) is completely bound in an inert complex AuLCl. When unbound L is exhausted, the newly formed AuLCl is accumulated in micellar shells, changes the properties of the medium inside the micelles, and affects the rate constant of the autocatalytic reaction, which increases with increasing cL. At high concentrations of L, the coagulation of particles occurs instead of their dissolution, because of the deterioration of the protective properties of micellar shells as a result of the ingression and accumulation of dioctyl sulfide molecules on account of selective adsorption on gold particles. The rate constants of all stages of dissolution and coagulation are determined.

Determination of optimum process conditions for solvent extraction of thorium using Taguchi method

Solvent extraction of thorium was studied using Taguchi method. The effect of various parameters such as acid types (sulfuric, nitric, hydrochloric, sulfuric ? nitric) and their concentrations from 0.001 to 4 M, initial thorium concentration (0.0001, 0.001, 0.01, 0.1 M) and solvent type (TBP, D2EHPA, Cyanex921, Cyanex272) in the ranges of 0.001 to 1 M on thorium extraction efficiency were investigated. The maximum extraction of thorium was obtained while 0.001 M hydrochloric acid, 0.001 or 0.01 M thorium and Cyanex272 were used. Under these optimum conditions, the extraction percent and distribution coefficient of thorium were 98.7% and 73.8, respectively. Compared with the hydrochloric aqueous solution, the nitric acid system showed less variation in the extraction of thorium. The proposed process has been applied for the separation of Th(IV), U(VI), La(III), and Ce(III) from synthetic solution same as thorium ores (monazite).

Removal of Sn(IV) Ions by Galvanostatic Electrolysis from Aqueous Hydrochloric Solution Containing Sn(IV) and In(III)

Removal of Sn(IV) Ions by Galvanostatic Electrolysis from Aqueous Hydrochloric Solution Containing Sn(IV) and In(III)