Effects of stannous ions on the electrochemical performance of the alkaline zinc electrode

The effect of stannous ions as an electrolyte additive on the electrodeposition characteristics of Zn was investigated by chronoamperometry, the potential-step method and cyclic voltammetry. The chronoamperometry measurements showed that the addition of stannous ions inhibited the dendritic growth of Zn deposits. SEM observation also revealed that the Zn deposit was in the form of compact cylinders with rounded tops that consist of many small crystallites, rather than the classical dendrites with side branches. The inhibition effect of Sn²⁺ on the very initial electrocrystallization of Zn was not a substrate effect. The 0.17 V difference in reduction potential between Zn and Sn resulted in the codeposition of Sn and Zn. An interruption effect was proposed to illuminate the inhibition effect of Sn²⁺ on the formation of Zn dendrites. Furthermore, Sn²⁺ additive was found to suppress the corrosion reaction of Zn by 87% in the Sn²⁺-containing zincate electrolyte, comparing to that in the blank zincate electrolyte.     

High-performance Sn–Ni alloy nanorod electrodes prepared by electrodeposition for lithium ion rechargeable batteries

To reduce irreversible capacity and improve cycle performance of tin used in lithium ion batteries, Sn–Ni alloy nanorod electrodes with different Sn/Ni ratios were prepared by an anodic aluminum oxide template-assisted electrodeposition method. The structural and electrochemical performance of the electrode were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, cyclic voltammetry, and galvanostatic charge–discharge cycling measurement. The results showed that the copper substrate is covered with uniformly distributed Sn–Ni alloy nanorods with an average diameter of 250 nm. Different phases (Sn, Ni₃Sn₄ and metastable phases) of alloy nanorod formed in the electrodeposition baths with different compositions of Sn²⁺ and Ni²⁺ ions. Sn–Ni alloy nanorod electrode delivered excellent capacity retention and rate performance.     

Kinetics of Sn electrodeposition from Sn(II)–citrate solutions

The influence of solution chemistry on the electrodeposition of Sn from Sn(II)–citrate solutions is studied. The distribution of various Sn(II)–citrate complexes and citrate ligands is calculated and the results presented as speciation diagrams. At a SnCl₂·H₂O concentration of 0.22 mol/L and citrate concentration from 0.30 mol/L to 0.66 mol/L, SnH₃L⁺ (where L represents the tetravalent citrate ligand) is the main species at pH below about 1.2 and SnHL⁻ is the main species at pH above about 4. Polarization studies and reduction potential calculations show that the Sn(II)–citrate complexes have similar reduction potentials at a given solution composition and pH. However, the Sn(II)–citrate complexes become more difficult to reduce with higher total citrate concentration and higher solution pH. Nevertheless, SnHL⁻ which forms at higher pH is a favored Sn(II)–citrate complex for Sn electrodeposition due to better plated film morphology, likely as a result of its slower electroplating kinetics. Precipitates are formed from the Sn(II)–citrate solutions after adding hydrochloric acid (to lower the pH). Compositional and structural analyses indicate that the precipitates may have the formula Sn₂L.     

Electrodeposition of eutectic Sn96.5Ag3.5 films from iodide–pyrophosphate solution

Electrodeposition of SnAg alloy films and the effect of additives like PEG-600 and hydrazine hydrochloride on the same were studied in KI–K₄P₂O₇ solutions. PEG-600 was found to adsorb on the electrode surface, resulting in strong reduction inhibition of tin pyrophosphate complex ions, but it does not affect the reduction of silver iodide complex. It was found that hydrazine hydrochloride acted as a reducing agent for Sn⁴⁺ species and greatly improved surface morphology and roughness of the films by preventing the formation of Sn dendrites during electrodeposition. Eutectic Sn_96.5Ag_3.5 was obtained from a plating solution that contained both PEG-600 and hydrazine hydrochloride as additives, at the deposition current density of 40 mA cm⁻². Stress measurements of the SnAg films showed that it was tensile. X-ray analysis of the deposit showed the presence of β-Sn and ?-Ag₃Sn phases in the eutectic SnAg film. The DSC profile of SnAg film gave the melting point as 222 °C.     

Bimetallic Pt–Sn/γ-alumina catalyst for highly selective liquid phase hydrogenation of diethyl succinate to γ-butyrolactone

Platinum–tin bimetallic catalyst on γ-alumina support was prepared by impregnation method and was reduced by sodium borohydride at room temperature. XRD and XPS characterization revealed that platinum was reduced to Pt⁰ while, tin was probably partially reduced to Sn²⁺ due to the low temperature reduction method and Sn⁰ was completely absent, avoiding the formation of Pt–Sn alloy. Pt–Sn/γ-alumina (Pt 1%, Sn 9%) thus prepared was found to give almost complete selectivity to γ-butyrolactone in liquid phase hydrogenation of diethyl succinate. A plausible reaction pathway is proposed involving Pt–O–Sn state and high selectivity to GBL is due to the Lewis acidity of Sn^2+/4+.     

Enhanced activity of PtSn/C anodic electrocatalyst prepared by formic acid reduction for direct ethanol fuel cells

The Pt₃Sn/C catalyst with high electrochemical activity was synthesized under optimizing preparation conditions. The surface of carbon support pretreated by strong acid contains many O-H and CO groups, which will increase the active sites of PtSn/C catalysts. The catalyst structure was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and temperature programmed reduction (TPR). The co-reduction of Pt⁴⁺ and Sn²⁺ ions causes Sn to enter Pt crystal lattice to form PtSn alloy whose surface, however, contains tin oxides with Sn⁴⁺ and Sn²⁺ valences, which can promote the ethanol oxidation. The crystallinity of PtSn decreases with the reduction of the atomic ratio of Pt:Sn. By prolonging the reaction time of formic acid, the forward anodic peak current of ethanol oxidation reaches 16.2 mA on the Pt₃Sn/C catalyst with 0.025 mg Pt loading.     

Ferromagnetic insulating behavior at low temperature induced by Sn doping in the ceramic SrRuO3

Effects of Sn doping at Ru site on the structural, magnetic, and transport behavior of polycrystalline SrRu_1−xSn_xO₃ (x ≤ 0.1) have been investigated here. Substitution of Sn⁴⁺ for Ru⁴⁺ remains the same crystal symmetry with that of Sn-free SrRuO₃, while induces the Ru(Sn)O₆ octahedral distortions. Samples with the low doping concentration (x ≤ 0.08) show a metallic behavior at high temperature, while a metal to insulator transition occurs at low temperature. On the other hand, an insulator behavior is detected for sample with x = 0.1, which follows Arrhenius-type process in the temperature range of 80–140 K and Mott's variable range hopping model in the temperature range of 140–300 K. Further, we find that Sn⁴⁺ has a significant effect on the magnetic behavior of Sn doping in SrRuO₃ where ferromagnetic transition temperature and magnetic moment decrease rapidly due to octahedral distortion and site dilution.     

Structure Characteristics and NO Selective Catalytic Reduction Property of Sn x Zr1-x O2 Solid Solution Catalysts

Novel catalysts, Sn_xZr_1-xO₂ solid solutions, for NO selective catalytic reduction:NO SCR) are reported. They have much higher activity and selectivity than SnO₂ and ZrO₂. Sn⁴⁺ is the main reductive sites as proved by TPR. The dilution of Sn sites by the coexisting Zr causes a suppression of propene combustion and consequently promoted the selective reduction of NO. The rutile structure might be beneficial to NO SCR.     

Thermal stability of tin charge states in the structure of the (As<Subscript>2</Subscript>Se<Subscript>3</Subscript>)<Subscript>0.4</Subscript>(SnSe)<Subscript>0.3</Subscript>(GeSe)<Subscript>0.3</Subscript> glass

Two valence states of tin atoms (namely, the doubly charged Sn²⁺ and quadruply charged Sn⁴⁺ states) in the structure of the (As₂Se₃)_0.4(SnSe)_0.3(GeSe)_0.3 glasses are identified by ¹¹⁹Sn Mössbauer spectroscopy. It is demonstrated that the concentration ratio of the doubly charged Sn²⁺ and quadruply charged Sn⁴⁺ states in the glass of this composition depends on the rate of quenching of the melt and on the initial temperature of the melt before quenching. The optical band gap and the activation energy for electrical conduction of the studied glass do not depend on the concentration ratio of the Sn²⁺ and Sn⁴⁺ ions. This behavior of the optical band gap and the activation energy is explained within the model according to which the structure of the glasses under investigation is built up of the structural units AsS_3/2, As_2/2Se_4/4, GeSe_4/2, SnSe_4/2, and SnSe_3/3, which correspond to the compounds AsSe₃, AsSe, GeSe₂, SnSe₂, and SnSe, respectively.     

Use of super absorbent hydrogels derivative from acrylamide with itaconic acid and itaconates to remove metal ions from aqueous solutions

Poly(acrylamide-co-itaconic acid) (AAm/IA) and poly(acrylamide-co-monomethoxyethyl itaconate) (AAm/MEI) hydrogels (HGs) synthesized at different molar ratios were used to study the adsorption of some metal ions as Cu²⁺, Ni²⁺, Pb²⁺, Cd²⁺, and Fe³⁺ in aqueous solutions at different concentration: 10, 50, 100, 500, and 1000 mg L⁻¹. Statistical analysis was performed and the effect of the metal ion, ion concentration, and hydrogel (HG) composition, on adsorption and adsorption efficiency, was evaluated for both HGs studied (AAm/IA and AAm/MEI) and each factor gave rise to significant differences (P ≤ 0.05). The adsorption depends on the type of ion, its concentration, and also influenced by the type and composition of the HGs. For each system the adsorption efficiencies for all ions were similar with exception of Fe³⁺, which showed the highest adsorption efficiency in AAm/MEI HG, but the less for the AAm/IA. For both systems, the maximum adsorption efficiency was observed when the molar ratio AAm/IA or AAm/MEI is 80/20. When the adsorption was carried out with individual ions, AAm/MEI HG was more efficient than AAm/IA. For a multielement sample of Cu²⁺, Ni²⁺, Pb²⁺, and Cd²⁺, both HGs could adsorb all the ions and their behavioral trend was the same in both cases, in which the adsorption efficiency was Pb²⁺ > Cu²⁺ > Cd²⁺ > Ni²⁺. The results of the statistical analysis evidence the advantage of its use in this type of studies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46999     

TLC of 48 Metal Ions on Silica Gel-G Plates in DMSO-HCI Systems

Abstract

The thin-layer chromatography of 48 metal ions has been performed in 29 DMSO-HCI solvent systems. The HC1 concentration varies from 1 to 6 M and the ratios of DMSO-HCI by volume are 1: 9, 3: 7, 5: 5,7: 3, and 9:1. A number of interesting separations have been achieved: e.g., Sn⁴⁺-Sn²⁺, Ti⁴⁺-Fe³⁺, Zr⁴⁺-UO₂ ²⁺, Zr⁴⁺-Th⁴⁺, Zr⁴⁺-La³⁺, Sn²⁺-Sb³⁺, and W⁶⁺ - MO⁶⁺-UO₂ ²⁺.     

The state of tin impurity atoms in vitreous germanium chalcogenides

Tin atoms formed after the radioactive decay of the ^119mmSn and ¹¹⁹Sb impurity atoms in the structure of Ge _x S_{1 ? x} and Ge _x Se_{1 ? x} glasses are stabilized in the form of Sn²⁺ and Sn⁴⁺ centers or in germanium nodes (after ^119mmSn decay), or in the nodes of structural units formed by ¹¹⁹Sb atoms. The Sn²⁺ and Sn⁴⁺ centers correspond to the ionized states of amphoteric two-electron tin center with negative correlation energy. ¹¹⁹Sn atoms formed after the radioactive decay of the ^119mTe atoms in the structure of Ge _x S_{1 ? x} and Ge _x Se_{1 ? x} glasses are stabilized in both chalcogen and germanium nodes.     

The two-electron exchange between the <Emphasis Type="Italic">U</Emphasis><Superscript>–</Superscript> tin centers in crystal and glass-like chalcogenide semiconductors

The two-electron exchange between neutral and doubly ionized U ^– tin centers in the partially compensated Pb_0.96Sn_0.02Na_0.01Tl_0.01S hole solid solutions in the temperature range of 80–900 K and in the partially compensated Pb_0.965Sn_0.015Na_0.01Tl_0.01Se hole solid solutions in the temperature range of 80–600 K was studied by ^119mm Sn(^119m Sn) Mössbauer spectroscopy. The activation energy of this process for the Pb_0.96Sn_0.02Na_0.01Tl_0.01S solid solutions is comparable with the depth of the tin energy levels in the PbS band gap and amounts to 0.11(2) eV, while in the Pb_0.965Sn_0.015Na_0.01Tl_0.01Se solid solutions it is comparable with the correlation energy of the donor U ^– tin centers in PbSe and amounts to 0.05(1) eV. It is established that the exchange is implemented by the simultaneous transfer of two electrons with the valence band states involved. In the glass-like (As₂Se₃)_0.3(GeSe)_0.6(SnSe)_0.1 alloy containing quadruply charged six-coordinated tin (singly ionized donor center) and doubly charged three-coordinated tin (singly ionized acceptor center), no traces of the electronic exchange between differently charged tin states was observed up to a temperature of 480 K, which is explained by the fact that the doubly charged and quadruply charged tin centers are in different coordination states.     

Adsorption of Pb2+ and Pd2+ on polyethylene membrane with amino group modified by radiation‐induced graft copolymerization

Six chelating hollow fiber membranes were prepared by radiation‐induced grafting of glycidyl methacrylate onto a polyethylene hollow fiber membrane and its subsequent amination. The adsorption characteristics of Pb²⁺ and Pd²⁺ for the chelating hollow fiber membranes were presented when the solution of Pb²⁺ and Pd²⁺ permeates across the chelating membrane, respectively. The degree of grafting for glycidyl methacrylate increases with increasing monomer concentration, reaction temperature, and preirradiation dose. The adsorption of Pd²⁺ by chelating hollow fiber membranes modified with five kinds of amines was in the following order: diethylene triamine > hexamethyl diamine > ethylene diamine > dimethyl amine > trimethyl amine. The chelating hollow fiber membrane modified with iminodiacetic acid adsorbed Pb²⁺ ions much more than Pd²⁺. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 643–650, 1999     

XRD studies of the phase composition of the electrodeposited copper-rich Cu-Sn alloys

Studies of the phase and chemical compositions as well as of the surface morphology of Cu-Sn alloys electrodeposited in the sulphate solution containing laprol were carried out using the XRD, SEM, and EDX techniques. The multiphase composition—pure copper, the α-CuSn phase and the intermediate hcp phase were determined to be present in the deposits obtained at cathode potentials positive to that of the reversible of the Sn/Sn²⁺electrode. When the content of Sn in the deposit was higher than 12-13 at.%, the β and/or δ phases were determined to be present along with that mentioned above. The deposit obtained at the potentials negative to that of the reversible of the Sn/Sn²⁺ electrode presented the δ phase with low quantities of the pure Cu and α-CuSn phases. The grain size of deposits increased with the cathode potential until it was positive to that of the reversible of the Sn/Sn²⁺ electrode. The presence of Br⁻ ions in the solution hindered the granular electrocrystallization and reduced the Sn proportion in the alloy. It was assumed that underpotential deposition (UPD) of Sn on copper could be responsible for the formation of the multiphase composition and the intermediate hcp phase. It was concluded that the brightness of the studied Cu-Sn coatings was conditioned by the surface morphology.     

Study of Co–Sn and Ni–Sn alloys prepared in molten chlorides and used as negative electrode in rechargeable lithium battery

Ni₃Sn₂ and several Co–Sn alloys prepared by electrodeposition in molten LiCl–KCl were studied as anode materials in rechargeable Li-ion battery. In the case of Ni₃Sn₂, the charge–discharge curves do not exhibit any plateau in contrast with Co–Sn alloys. For Ni₃Sn₂, the reversible capacity and the coulombic efficiency tend to constant values of about 225 mAh/g and 85%, respectively, after subsequent cycles. Among the studied Co–Sn alloys, the best electrochemical performances was observed when CoSn₂ was used as anode material: the reversible capacity and the coulombic efficiency observed after 60 cycles were about 530 mAh/g and 96%, respectively. Whatever the alloys, SEM investigations performed before and after cycling do not reveal any significant difference between the original material and the cycled material, indicating a good stability of the electrodeposited films upon cycling.     

Effect of magnesium carbonate on the uptake of aqueous zinc and lead ions by natural kaolinite and clinoptilolite

Adsorption behavior of Zn²⁺ and Pb²⁺ ions on kaolinite and clinoptilolite, originating from natural resources, was studied as a function of contact time and concentration. Zn²⁺ and Pb²⁺ ions are quickly adsorbed on both minerals and the uptake of the latter is more favored. The uptake of both ions was then examined on kaolinite–MgCO₃ and clinoptilolite–MgCO₃ mixtures over a metal ions range from 1 to 10 000 mg/L. The sorption behavior of Zn²⁺ and Pb²⁺ on pure MgCO₃ was also studied. MgCO₃ is much more effective in the retention of Zn²⁺ and Pb²⁺ ions, in particular at higher concentrations. The large increase in the retarded amounts of both ions was associated with formation of the hydroxy-carbonate phases; namely hydrozincite for Zn²⁺, and cerussite and hydrocerussite in the case of Pb²⁺.     

Removal of cadmium or lead from polluted water by biological amphiphiles

Biological amphiphiles were examined for the removal of Cd²⁺ or Pb²⁺ from polluted water within a pH range from 2.5 to 7.5 at a fixed ratio of amphiphilic concentration to heavy metal concentration (C _A /C _M ) on a molar basis of approximately 11. Tannic acid, among eight amphiphiles, was selected for Cd²⁺ or Pb²⁺ removal because it exerted noticeable improvement within limited pH ranges. In the presence of tannic acid, the removal of Cd²⁺ or Pb²⁺ was investigated as a function of pH ranging from 2.5 to 13 at C _A /C _M ratios from 1.2 to 11. The removal capacity (mass of metal/mass of tannic acid) increased with decreasing C _A /C _M for both Cd²⁺ and Pb²⁺. Removal capacities were 0.084 and 0.154 g/g-tannic acid for Cd²⁺ and Pb²⁺ at pH 6.9 and 4.4, respectively. The maximal removals for Cd²⁺ and Pb²⁺ were 99 and 96%, respectively.     

Poly(itaconic acid)-assisted ultrafiltration of heavy metal ions’ removal from wastewater

The complexation–ultrafiltration technique has been introduced as a capable system to remove heavy metals ions from wastewater. This method needs a water-soluble polymer; therefore, in this paper we synthesized super water-soluble poly(itaconic acid) (PITA) and employed it in polymer-assisted ultrafiltration process to remove Pb(II) ions from synthetic wastewater solutions. The itaconic acid can be produced from different agricultural products and is a green and eco-friendly material. Factors influencing the removal of the metals ions including poly(itaconic acid) concentration, pH and permeate flux were investigated. The results showed that the maximum percentage of metal ion removal was obtained in the basic pH (pH > 7). The flux test was performed by 200 mg/L of poly(itaconic acid) and after 60 min, the flux of membrane was 33.4 L/m²h. The simultaneously selective removal ability of the poly(itaconic acid) for adsorption of different metal ions (Pb²⁺, Sn²⁺, Cu²⁺, Zn²⁺, and Cd²⁺) was also studied. The trend of rejection was Pb²⁺ > Cu²⁺ > Sn²⁺ > Zn²⁺ > Cd²⁺. The highest rejection of Pb(II) ions was achieved as 86%. Generally, the results of this research demonstrated that poly(itaconic acid) (with two carboxyl groups on its repeating unit) is more effective in removing heavy metals ions from wastewater in comparison with customary polymers.

     

Codeposition of copper and tin from acid sulphate solutions containing polyether sintanol DS-10 and benzaldehyde

Cu(II) and Sn(II) reduction in acid sulphate solutions containing polyether laprol DS-10 and benzaldehyde (BA) was studied by means of impedance, voltammetric, XPS and XRD techniques. Both additives demonstrate weak surface activity on copper substrate in Cu(II) solutions in the absence of halide impurities. In contrast, their effect is overwhelmingly higher in the Sn|Sn(II) system. The additives induce a significant increase in Sn-electrode impedance and simultaneous strong inhibition of Sn(II) reduction over a wide range of cathodic polarizations. The effects of sintanol and BA in mixed Cu(II) and Sn(II) solutions demonstrate a kind of synergism. Underpotential deposition of tin on foreign (copper) substrate is observed at potentials more positive than the equilibrium potential of the Sn|Sn²⁺ system. Incorporation of tin into the Cu crystalline lattice results in the formation of multiphase material containing pure copper, α-CuSn phase, and intermediate hexagonal hcp phase. Formation of the pure tin phase occurs at more negative potentials and results in a strong inhibitive adsorption that manifests itself in the development of a deep voltammetric minimum. The tin content in the coatings depends on BA concentration and, particularly, on the electrode potential.