Aqueous Hydrochloric Acid Solutions Research Articles

Ion Exchange Recovery of Platinum(IV) from Hydrochloric Acid Solutions in the Presence of Silver(I)

The ion exchange sorption of the platinum(IV) chloride complexes in the presence of silver(I) chloro complexes from 2 and 4 M aqueous solutions of hydrochloric acid is studied on Purolite anion exchangers with different functional groups. The high selectivity of the investigated sorbents with respect to platinum during its recovery from individual hydrochloric acid solutions and in the presence of silver chloride complexes is determined. Since the latter are in this case virtually not sorbed in the presence of platinum(IV), they can be separated at the stage of sorption. The excellent kinetic properties of the investigated anion exchangers are revealed, allowing platinum to be eluted after its separation from silver chloro complexes in a dynamic mode.

Synthesis, characterization, morphology and adsorption performance towards cu+2 ions of nano-sized copolymers of anthranilic acid and o-aminophenol poly(anthranilic acid-co-o-aminophenol)

Nanospheres with different particles size and nanorodes of copolymer of anthranilic acid with o-aminophenol poly(AA-co-o-AP) were synthesized by redox polymerization initiated by FeSO4.7H2O as redox initiator and ammonium peroxydisulfate (APS) as oxidant in different concentrations of aqueous solutions of hydrochloric acid. The influence of synthetic parameters such as acid concentration and the presence of redox initiator were investigated. The morphology and particles size were studied by transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the morphology and average particle size of polymeric nano particles according to SEM and TEM analyses were different based upon the conditions of the copolymerization. The physico-chemical characterization of the prepared nanoparticles was carried out by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and Thermogravimetric(TGA). Which FT-IR confirmed the structure of poly(AA-co-o-AP) nanoparticles in emeraldine form. The molecular weight was determined by gel permeation chromatography (GPC). The surface area of nanocopolymer particles was determined also by Brunauer-Emmett-Teller (BET). The competition of the prepared nano-sized copolymers particles towards the adsorption of copper ions from aqueous solutions was investigated. The results showed that the adsorption capacity was based on particle size of nanocopolymers and their surface area. The adsorption capacity increased with decreasing the particle size. On the other hand the adsorption capacity increased with increasing the surface area and the molecular weight of the prepared nano-sized copolymers of poly(AA-co-o-AP).

Инкапсуляция изохинолина в полимерном наноконтейнере на основе сульфокатионита КУ-2-4

The possibility of the encapsulation of isoquinoline in the nanocontainer on the matrix of the sulfonated copolymer based on styrene and divinylbenzene (CU-2-4 sulfocationite) has been researched. The encapsulation of isoquinoline in the nanocontainer on polymer matrix was performed by ion-exchange sorption from aqueous solutions. CU-2-4 sulfocationite in hydrogen and isoquinoline forms was studied by NMR and Fourier IR spectroscopy. In the 13C NMR spectra of solid-state samples of the CU-2-4 cation exchanger in the isoquinoline form is observed additional resonance absorption band of 13C in the range of chemical shift 136 ppm, corresponding to the nodal carbon atom of the pyridine ring. The IR spectrum of the polymer containing the encapsulated isoquinoline be observed bands characteristic for skeletal vibrations in the area of isoquinoline fingerprints (1300-1600 cm-1) and the band of 938 cm-1 that corresponds to the deformation vibrations of the CH-group of pyridine ring, which is not in the spectrum of the H-form sulfocationite. The ion-exchange capacity of the nanocontainer based on СU-2-4 sulfocationite for isoquinoline was 5.5 meq/g. This corresponds to the content of ionogenic groups in the polymer. The dynamic ion-exchange capacity of sulfonated CU-2-4 cation exchanger during encapsulation of isoquinoline coincides with the ion-exchange capacity of sulfonated cation exchanger upon the release of isoquinoline from the polymer nanocontainer. The content of immobilized isoquinoline in the nanocontainer on the СU-2-4 matrix reaches 71 % by weight of the polymer. It is shown that isoquinoline is encapsulated and desorbed with the solution of hydrochloric acid at the same rate. Encapsulated isoquinoline is completely released from the polymer by desorption with the aqueous hydrochloric acid solution. The half-life during sorption and desorption (release) of isoquinoline is approximately 400 seconds. It is shown that the encapsulated isoquinoline to be completely released from the polymer by desorption with an aqueous hydrochloric acid solution. The kinetics of the encapsulation and release of isoquinoline from the nanocontainer based on CU-2-4 sulfocationite is determined by its diffusion in the polymer phase.

Hydrogen production by aluminum corrosion in aqueous hydrochloric acid solution promoted by sodium molybdate dihydrate

Recycled aluminum alloys corrosion system was studied for hydrogen production in 1.4 M HCl solution at low temperature, 333 K. Molybdate ions were used as corrosion promoter. Commercial Na2MoO4·2H2O was tested, varying its concentration (0–0.036 M) in order to analyze the promoter effect in H2 production. Moreover, Na2MoO4·2H2O particles were synthesized via sonochemical method and by ultrasonic method. Later, synthesized promoters were tested in order to analyze the effect of their physicochemical properties in H2 production. Gas composition produced during the reaction was analyzed by gas chromatography. Results showed that reaction rate was notorious affected by molybdate ions concentration. The highest hydrogen volume and the greatest reaction rate obtained was with the use of 1050 aluminum foil alloy with very low promotor concentration (0.004 M), becoming, therefore, a low-cost process for high purity hydrogen production.

Study of the adsorption/desorption of MB dye solution using bentonite adsorbent coating

Re-usability of exhausted or spent adsorbent in water treatment plant is became a complicated issue. In this regard, exhausted bentonite adsorbent has been employed for desorption/regeneration using combined effect of heating and solvent regeneration method. Exhausted adsorbent has been characterized using FTIR, and SEM analyses. The results of regeneration study reveal effective desorption of methylene blue (MB) dye up to seven successive cycles. Among different solvents (aqueous solution of hydrochloric acid, ethanol, acetone, propanol, nitric acid, water, NaCl and NaOH), significant desorption of MB (70 %) was achieved using aqueous HCl solution. To optimized maximum desorption of MB, different physico-chemical parameters such as temperature, initial dye concentration, contact time and lifespan of adsorbent have been studied. In addition, desorption isotherm and desorption kinetics were also found to be fitted with Sips isotherm (R2 = 0.995) and second-order kinetics models (R2 = 0.990), respectively. Moreover, chemically treated adsorbent (Paintosorp™) can be effectively used up to seven adsorption/desorption cycles.

Ceramic-like stable CsPbBr3 nanocrystals encapsulated in silica derived from molecular sieve templates

Achieving good stability while maintaining excellent properties is one of the main challenges for enhancing the competitiveness of luminescent perovskite CsPbX3 (X=Cl, Br, I) nanocrystals (NCs). Here, we propose a facile strategy to synthesize ceramic-like stable and highly luminescent CsPbBr3 NCs by encapsulating them into silica derived from molecular sieve templates at high temperature (600–900 oC). The obtained CsPbBr3-SiO2 powders not only show high photoluminescence quantum yield (~71%), but also show an exceptional stability comparable to the ceramic Sr2SiO4:Eu2+ green phosphor. They can maintain 100% of their photoluminescence value under illumination on blue light-emitting diodes (LEDs) chips (20 mA, 2.7 V) for 1000 h, and can also survive in a harsh hydrochloric acid aqueous solution (1 M) for 50 days. We believe that the above robust stabilities will significantly enhance the potential of perovskite CsPbX3 NCs to be practically applied in LEDs and backlight displays.

Equilibrium thickness of foam films and adsorption of ions at surfaces: Water and aqueous solutions of sodium chloride, hydrochloric acid, and sodium hydroxide

HypothesisThe origin of negative surface charge at water/air interface is still not clear. The most probable origin is specific adsorption of OH− ions. From diffuse layer potential, we can evaluate the surface density of ions in the Stern layer which can be a measure for the specific adsorption of ions and determines whether the surface charge is solely due to the specific adsorption of OH− ions. ExperimentsEquilibrium thickness of foam films of pure water and aqueous solutions of NaCl, HCl, and NaOH was measured as a function of disjoining pressure for water and as a function of concentration for the aqueous solutions at 298.15 K. Quartz-glass cells thoroughly cleaned and immersed in pure water before use were used for the measurement. FindingsApplication of a modified Poisson-Boltzmann equation to the equilibrium film thickness gave the diffuse layer potential and the surface density of ions in the Stern layer. From the concentration dependence of the surface density, it was concluded that not only OH− ions but also Cl− ions and HCO3− and/or CO32− ions adsorb specifically at the water/air interface.

Recovery of yttrium and europium from spent fluorescent lamps using pure levulinic acid and the deep eutectic solvent levulinic acid-choline chloride.

A solvometallurgical approach for the recovery of rare-earth elements from lamp phosphor waste was developed. The solubility of individual phosphors in different deep-eutectic solvents (DESs) was measured. The DES levulinic acid–choline chloride (xChCl = 0.33) showed high solubility of the YOX phosphor (Y2O3:Eu3+) and low solubility of the HALO phosphor (Sr,Ca)10(PO4)(Cl,F)2:Sb3+,Mn2+, which does not contain any rare-earth element. This DES was selected for further investigation. When the DES was compared to pure levulinic acid, very similar leaching behaviour was observed, showing that the proton activity is more important than the chloride as a metal ligand. The leaching of YOX and HALO using levulinic acid–choline chloride (xChCl = 0.33) or pure levulinic acid was optimised in terms of water content, temperature and leaching time. The optimised parameters were validated in a synthetic mixture of phosphors and in real lamp phosphor waste. The co-dissolution of HALO is higher in the real waste than in the synthetic mixture. The real waste was also leached with an aqueous solution of hydrochloric acid, which was non-selective against dissolution of YOX, and with the functionalised ionic liquid betainium bis(trifluoromethylsulfonyl)imide. The ionic liquid gave a similar selectivity as levulinic acid, but is much more expensive. The recovery of the metals from the pregnant leach solution was tested via precipitation with oxalic acid and solvent extraction. Oxalic acid precipitation was not suitable for the DES system. The metals could be extracted via solvent extraction with the acidic extractant bis(2-ethylhexyl)phosphoric acid (D2EHPA) and stripped by an aqueous hydrochloric acid solution. Pure levulinic acid was found to be more suitable than the corresponding ChCl-based DES for the selective recovery of YOX.

Kinetics of silver dissolution in aqueous solutions of hydrochloric acid

Kinetics of silver dissolution in aqueous solutions of hydrochloric acid

Adsorption of Hydrogen Sulphide by Commercialized Rice Husk Biochar (RHB) & Hydrogel Biochar Composite (RH-HBC)

Hydrogen sulfide (H2S) is a naturally occurring component found during microbial disintegration and processing of natural gas & oil which can cause wellbeing and condition issue if being discharged into a climate at high fixation. Activated carbon which cost a lot in manufacturing is used as an adsorbent for removing these hazardous gases. As an alternative, the abundance waste of biomass available can be converted into good use. Biochar is one of the most practical and promising adsorbents that shows incredible potential as an adsorbent for the expulsion of contaminants in wastewater and gas treatment. This study covered on the characteristics and adsorption performance of two adsorbents Activated Rice Husk Biochar (RHB) and Rice Husk Hydrogel Composite (RH-HBC) on hydrogen sulfide. RHB is prepared by treating grinded rice husk biochar using aqueous Zinc Chloride (ZnCl2) and hydrochloric acid (HCl) solution to increase the size of pores of active sites and remove the impurities present in on the adsorbents. Polymerization is conducted by using initiator (ammonium persulfate, APS), monomer (acrylamide, AAm) and crosslinker (N,N'-methylenebisacrylamide,MBA) to create treated hydrogel biochar (RH-HBC). The adsorption performance is done to evaluate the effect of sorbent weight (20 g, 25 g, 30 g), H2S gas flow rate (200 L/hr, 150 L/hr, 100 L/hr) and temperature (30℃, 50℃, 70℃). RHB shows better porosity compared to RH-HBC where it has a higher surface area (222.85m2/g) compared to RH-HBC (8.68m2/g). While the presence of alkene group C=C in RH-HBC gives more stability to withstand high temperature compared to RHB. From the result, it can be concluded that the increased the sorbent weight, give an increased in adsorption capacity. When increased the gas flow rate, it gives a shorter contact time between gas and adsorbent which result in less adsorption capacity. RH-HBC give longest breakthrough time and highest adsorption capacity compared with RHB in all experiment.

Effects of boron oxide composition, structure, and morphology on B4C formation via the SHS process in the B2O3–Mg – C ternary system

This study investigates the formation of B4C in the B2O3–Mg–C ternary system via a magnesiothermic reduction process using two kinds of boron oxide (B2O3) ‒ the commercial B2O3 and that synthesized from boric acid via the coupled chemical-thermal process. In addition to the raw materials, the products were subjected to XRD, FTIR, SEM, and FESEM analyses to determine the effects of microstructural and morphological properties of boron oxide as an important raw material, on B4C formation in the combustion synthesis process. For this purpose, powder mixtures of B2O3:Mg:C were prepared at a stoichiometric molar ratio of 2:6:1 and compacted into pellets using a uniaxial hydraulic press, which were subsequently subjected to the combustion synthesis process based on the self-propagating high-temperature synthesis (SHS). Finally, the samples thus obtained were leached in an aqueous hydrochloric acid solution. Analysis of the commercial B2O3 revealed the presence of large amounts of such by-products as magnesium borate (Mg3B2O6) and magnesium oxide (MgO) along with relatively small amounts of boron carbide after the leaching process, while those obtained for the chemically-thermally synthesized B2O3 showed a relatively large amount of B4C (from micron-sized particles to nanoparticles) together with a remaining carbon phase and very small amounts of magnesium borate as by-products. It can be, therefore, concluded that the changes in chemical composition and introduction of a hydrous HBO2 phase in the boron oxide in the B2O3–Mg–C mixture as well as its varied microstructure, morphology, and particle size have significant effects on the efficiency of B4C production through the SHS process.

Enhanced photocatalytic hydrogen production activity of highly crystalline carbon nitride synthesized by hydrochloric acid treatment

Crystalline carbon nitride (CCN) prepared by a molten-salt method is attracting increased attention because of its promising properties and excellent photocatalytic activity. In this work, we further improve the crystallinity of CCN through synthesis by the molten-salt method under the action of aqueous hydrochloric acid (HCl) solution. Our results showed that the cryst allinity of the as-prepared samples increased with increasing HCl concentration and reached the maximum value at 0.1 mol L−1. This can be attributed to the removal of some potassium ions (K+) from the terminal amino groups of CCN by the aqueous HCl solution, which results in a release of the polymerization sites. As a result, the crystallinity of the as-prepared samples further increased. Moreover, the obtained 0.1 highly crystalline carbon nitride (0.1HCCN; treated with 0.1 mol L−1 aqueous HCl solution) exhibited an excellent photocatalytic hydrogen evolution of 683.54 µmol h−1 g−1 and a quantum efficiency of 6.6% at 420 nm with triethanolamine as the sacrificial agent. This photocatalytic hydrogen evolution was 2 and 10 times higher than those of CCN and bulk carbon nitride, respectively. The enhanced photocatalytic activity was attributed to the improved crystallinity and intercalation of K+ into the xHCCN interlayer. The improved crystallinity can decrease the number of surface defects and hydrogen bonds in the as-prepared sample, thereby increasing the mobility of the photoinduced carriers and reducing the recombination sites of the electron–hole pairs. The K+ intercalated into the xHCCN interlayer also promoted the transfer of the photoinduced electrons because these ions can increase the electronic delocalization and extend the π-conjugated systems. This study may provide new insights into the further development of the molten-salt method.

An Exemplar Imidazoline Surfactant for Corrosion Inhibitor Studies: Synthesis, Characterization, and Physicochemical Properties

AbstractAn optimized one‐pot recipe has been developed to synthesize a surfactant molecule, referred to as OMID, consisting of an imidazoline head group and aliphatic tail, which is an exemplar corrosion inhibitor for carbon steel in acidic solutions. As evidenced by gas chromatography, 1H and 13C nuclear magnetic resonance, and Fourier‐transform infrared data, a high‐purity product was achieved without the use of either a solvent or catalyst. Critical micelle concentration values and corrosion inhibition efficiencies ( η%) were determined in aqueous solutions of hydrochloric acid and sulfuric acid using surface tensiometry and linear polarization resistance measurements, respectively. Hydrolysis of the imidazoline head group as a function of pH (0–11) was explored with ultraviolet–visible absorption spectroscopy. In addition, N 1s and C 1s X‐ray photoelectron spectroscopy data were acquired from both surface‐adsorbed OMID and a multilayer of the imidazoline head group of OMID. These latter data are highly relevant to those attempting to understand OMID inhibition chemistry.

New Δ8,9-pregnene steroids isolated from the extremophile fungus Exophiala oligosperma

Three pregnene steroids, two of them new, were isolated from ethyl-acetate partition of liquid-cultivation of the extremophyle fungus Exophiala oligosperma, found in a pH 1.5 hydrochloric acid aqueous solution. Spectroscopic studies using NMR and HRMS, allowed the identification of the molecular structures of both Δ8,9-pregnenes, still not described in the literature.

Enhanced removal performance for Congo red by coal-series kaolin with acid treatment

ABSTRACT In this study, acid treatment coal-series kaolin (AK) materials (named 2AK, 3AK, 5AK, 10AK) were synthesized by a facile method. Batch adsorption experiments were carried out using Congo red (CR) as a model dye pollutant in various experimental conditions. The samples were studied by XRF, XRD, FTIR, SEM, Zeta potential and N2 adsorption techniques. The results indicate that the acid treatment materials exhibit increased specific surface area and pore structures, and showed obvious effects on the adsorption performance of kaolin. Owing to the structural edges of kaolin receiving protons from the hydrochloric acid aqueous solution, the prepared 5AK exhibited excellent adsorption performance for Congo red (CR) anionic dye. The adsorption process followed a pseudo-second-order rate model and the Langmuir isotherm was found a better fit with a maximum adsorption capacity of 237.53 mg/g, which is very close to the experimental data. Thermodynamic studies showed Congo red adsorption on samples was exothermic and spontaneous in nature. The acid treatment coal-series kaolin shows significant potential applications in the fields of adsorption, pH-responsive delivery and other environmental remediation.

Synthesis, characterization, morphology and adsorption performance towards Cu+2 ions of nano-sized copolymers of anthranilic acid and o-phenylenediamine poly(AA-co-o-PD)

Nanorodes, nanosheets, nanospheres and nano-amorphous shape with different particles size of copolymer of anthranilic acid with o-phenylenediamine poly(AA-co-o-PD) were synthesized by redox polymerization initiated by FeSO4.7H2O as redox initiator and ammonium peroxydisulfate (APS) as oxidant in different concentrations of aqueous solutions of hydrochloric acid. The influence of synthetic parameters such as acid concentration and the presence of redox initiator were investigated. The morphology and particles size were studied by transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the morphology and average particle size of polymeric nano particles according to SEM and TEM analyses were different based upon the conditions of the copolymerization. The physico-chemical characterization of the prepared nanoparticles was carried out by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD). Which FT-IR confirmed the structure of poly(AA-co-o-PD) nanoparticles in emeraldine form. The molecular weight was determined by gel permeation chromatography (GPC). The surface area of nanocopolymer particles was determined also by Brunauer-Emmett-Teller (BET). The competition of the prepared nano-sized copolymers particles towards the adsorption of copper ions from aqueous solutions was investigated. The results showed that the adsorption capacity was based on particle size of nanocopolymers and their surface area. The adsorption capacity increased with decreasing the particle size. On the other hand the adsorption capacity increased with increasing the surface area of the prepared nano-sized copolymers of poly(AA-co-o-PD).

Corrosion Resistance of Sintered Commercially Pure Titanium in Inorganic Acids after Oxidation and Nitriding

The corrosion resistance of oxidized and nitrided commercially pure titanium obtained by sintering of powders of titanium, titanium hydride and their mixtures was evaluated in 20% aqueous solution of hydrochloric acid and 40% aqueous solution of sulfuric acid. It was determined that surface oxide film decreased the corrosion rate by three orders of magnitude for titanium obtained by powder metallurgy, and by one order for titanium obtained by deformation technology. In the absence of a surface film at oxidation of the sintered titanium, the corrosion rate decreased by 1–2 orders of magnitude compared to untreated titanium. It was shown that stage nitriding led to decrease in corrosion rate by 3–4 orders of magnitude for titanium obtained by both technologies.

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.

Kinetics of Thallium Dissolution in Aqueous Solutions of Hydrochloric Acid

Potentiometry is used to study the kinetics of electrochemical oxidation and reduction of thallium in aqueous solutions of hydrochloric acid. Kinetic parameters are calculated to characterize the mechanism of the electro-oxidation of thallium: coefficient of diffusion D, heterogeneous rate constant ks of the electrode process, and effective activation energy Eeff. The effect the modes of electrolysis (current density, electrolyte concentration, and temperature) have on the dimensional characteristics of the obtained thallium(I) chloride is studied. The optimum parameters of electrolysis for preparing dispersed powders of thallium(I) chloride are revealed.

Spectroscopic and calorimetric studies of interactions between mitoxantrone and cucurbituril Q7 in aqueous solutions

Fluorimetric, DOSY NMR and calorimetric studies indicate that the mitoxantrone (L) molecule is complexed by cucurbituril Q7 (Q) in diluted aqueous hydrochloric acid solutions (pH = 4–5). The process of creating a supramolecular complex with a 1: 2 stoichiometry (Q2L) is thermodynamically spontaneous (∆G < 0), strongly exothermic (∆H < 0) and is accompanied by an increasing order of reagents (T∆S < 0). The calculated equilibrium constant logK > 3 indicates that the resulting supramolecular complex is thermodynamically stable. The increase in electrolyte concentration (10 mM formate buffer with 140 mM NaCl) impedes the interaction of mitoxantrone with cucurbituril Q7 in an aqueous environment.