Removal of tungsten and vanadium from molybdate solutions using ion exchange resin

The removal of tungsten (W) and vanadium (V) from molybdate solutions was studied using the poly hydroxyl chelating resin D403 in batch and column experiments. The batch experiments indicated that tungsten and vanadium could be preferentially adsorbed by the D403 resin for 4 h in molybdate solution at a pH of approximately 9.25. Separation factors, α_Mo^V and α_Mo^W, were above 45 and 18, respectively, when the molar ratios of Mo/V and Mo/W in the solution exceeded 40. Elution tests illustrated that vanadium and tungsten could be easily eluted from the resin with 1 mol/L sodium hydroxide solution in only 1 h. To further explore the sorption mechanism of the resin, the experimental equilibrium isotherm data of the three metals fitted well with the Freundlich model. The column experiments confirmed the adaptability of the D403 resin in the production of sodium molybdate with a removal rate of tungsten surpassing 90% and that of vanadium of 99.4%.     

Removal of copper from nickel anode electrolyte through ion exchange

An novel method for removal of copper from nickel anodic electrolyte through ion exchange was studied after cupric deoxidization. Orthogonal design experiments show the optimum conditions of deoxidizing cupric into Cu+ in the nickel electrolyte are the reductive agent dosage is 4.5 times as the theoretic dosage and reaction time is 0.5 h at 40 ℃ and pH 2.0. Ion exchange experiments show that the breakthrough capacity(Y) decreases with the increase of the linear flow rate(X): Y=1.559-0.194X+ 0.006 7X2. Breakthrough capacity increases with the increase of the ratio of height to radius(RRH). The higher the initial copper concentration, the less the breakthrough capacity(BC). SO42- and nickel concentration have no obvious change during the process of sorption, so it is not necessary to worry about the loss of nickel during the sorption process. Desorption experiments show that copper desorption from the resin is made perfectly with NaCl solution added with 4% (volume fraction) H2O2 (30%) and more than 100 g/L CuCl2 solution is achieved.     

Electrodeposition,characterisation and mathematical model of nickel–iron film in a parallel plate flow system

Abstract

Nickel–Iron alloy films were electrodeposited in a parallel plate flow system. The volumetric flow rate of electrolyte was fixed at 12 dm³ min^?1 through the 1 cm thick and 9 cm wide slit parallel plate. Fluid velocity was ca 0.22 m s^?1 under fully turbulent convective flow. Alloy films with iron content varying from 7·5 to 40 wt-% were deposited as a function of solution pH, temperature, bath ingredient concentration and applied current density. It is shown that the magnetic property is strongly correlated to the alloy content: the saturation moment, B _s, increases with the iron composition, while the coercivity, H _c, increases with nickel content. Current efficiency increases with pH and applied current density. The nickel deposition rate is inhibited in the presence of ferrous ion in the plating bath. The microhardness of the deposit is increased as the iron content is increased over the range studied. A mathematical model that considers the convective mass transfer of Fe(II) and Ni(II) species in the diffusion layer, the competition of adsorbed metal species on surface active sites, and Tafel electrochemical kinetics describe the alloy plating system well.     

Adsorption properties of Ag（Ⅰ）, Au（Ⅲ）, Pd（Ⅱ） and Pt（Ⅳ） ions on commercial 717 anion-exchange resin

The adsorption properties of the four precious metal ions (Ag(I), Au(II), Pd(III) and Pt(IV)) on the commercial Cl^?-form 717 strongly basic anion-exchange resin were studied in detail. The effects of the contact time, solution acidity, and concentrations of Cl^? and Pb²⁺ ions on the adsorption properties were studied by the batch method. Then, the column method was conducted under the optimized adsorption conditions (pH=3.0). The effects of the sample loading flow rate and the length-to-diameter ratios of the columns were investigated. The precious metal ions adsorbed could not be eluted completely after the saturated adsorption because the precious metal ions were found to be reduced to their metallic states during the adsorption process. So, it is recommended that the commercial Cl^?-form 717 strongly basic anion-exchange resin should be decomposed directly to recovery the precious metals after the saturated adsorption.     

Characteristics of nickel sulphide reduction in Ni2+ free background and Watts nickel plating electrolytes

Abstract

The electrochemical behaviour and composition of nickel sulphide coatings deposited on glassy carbon (GC) electrode by the successive ionic layer adsorption and reaction (SILAR) method using a nickel(II) ammonia complex and Na₂S solutions have been studied in Ni²⁺ free background, Watts nickel plating and 0·05 M H₂SO₄ electrolytes by the cyclic voltammetry and X-ray photoelectron spectroscopy (XPS) methods. Analysis of XPS data suggests that the coating is a mixture of two sulphides where NiS dominates. In the Ni²⁺ free background solution at first the electrochemical reduction of the sulphur rich nickel sulphide to NiS occurs. After that the NiS to metallic Ni is reduced in the potential range of H₂ evolution. During the cathodic reduction of the coating in Watts nickel plating electrolyte the sulphur is reduced in the potential range from 0·0 to ?0·4 V, while at the potential values <?0·5 V the sulphur rich nickel sulphide and NiS reduction in the H₂ evolution range and Ni plating occur.     

Regeneration and decontamination of a nickel citrate complex in spent electroless nickel plating solutions

The possibility of citrate precipitation by excess metal ions in alkaline solutions suggests the use of Ni(II) together with OH^? to precipitate a Ni(II)-citrate complex from spent electroless plating solutions. After treatment of the precipitate with acid, excess Ni(II) can be removed in the form of insoluble Ni(OH)₂. The solution of the Ni(II)-citrate complex can then be reused for electroless nickel plating. During this procedure the additive adipate is not regenerated. For decontamination of spent electroless nickel plating solutions Fe(III) can be used as Ni(II)-citrate complex precipitant.     

Electroless nickel deposition on silane modified bamboo fabric through silver,copper or nickel activation

Palladium-free process for the electroless nickel deposition on bamboo fabric (BF) has been developed. The process is based on 3-aminopropyltrimethoxysilane (APTMS) chemically grafted onto BF via a simple etchless method. Hence, Ni/BF composites can be obtained in three steps, namely: (i) the grafting of APTMS onto BF, (ii) the silver (Ag⁰), copper (Cu⁰) or nickel (Ni⁰) activating of the BF surface, and (iii) the nickel metallization using electroless plating bath. IR, XPS, XRD and SEM were used to characterize each step of the process. The nickel coating through silver activation has a smoother surface, higher electrical conductivity and better electromagnetic interference shielding effectiveness (EMI SE) by comparing to the other two activation samples. Magnetic property of the Ni/BF composites was measured, and composite from Ni activation has a larger saturation magnetization than the two left composites. All the nickel coatings via different metal activations are adhered firmly to the BF substrates, as determined by a standard adhesive Scotch®-tape test.     

Adsorption behavior of heptyl xanthate on surface of ZnO and Cu(II) activated ZnO using continuous online in situ ATR-FTIR technology

A continuous online in situ attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopic technique was used to investigate the adsorption and desorption kinetics of heptyl xanthate (KHX) on the surface of ZnO and Cu(II) activated ZnO. The results showed that Cu(II) facilitated the xanthate adsorption process on the surface, and led to the formation of cuprous xanthate (CuX), dixanthogen (X₂) and xanthate aggregates. The adsorption of xanthate on the surface of ZnO and Cu(II) activated ZnO was found to both follow the pseudo-first-order kinetic model. When the NaOH solution was used as a desorption agent, the adsorbed xanthate can largely be removed due to the competition between OH^? and HX^?. However, for Cu(II) activated ZnO, the peak intensities at 1197 and 1082 cm^?1 had no obvious weakening, and the absorption intensities at 1261 and 1026 cm^?1 increased in the first 5 min, indicating an ion-exchange reaction between OH^? and surface zinc bonded xanthate HX^? and the reorganization of adsorbed xanthate.     

Electrochemical characteristics of 316l stainless steel processed with a thermally treated Ni- and Cr-rich surface coating

The influence of a thermally treated Ni-Cr rich protective coating on the corrosion behavior and contact resistance of stainless steel in a 0.1NH₂SO₄+ 2 ppmHF electrolyte at 80 °C was evaluated using electrochemicals, interfacial contact resistance (ICR) measurements and X-ray photoelectron spectroscopy. Through a low-cost, continuous production line, the Ni-rich coating film for stainless steels was developed by dipping steel samples in acrylic resin and CrO₃ solutions with different levels of NiSO₄·6H₂O added as a nickel source. Each sample was then heated at 800 for 10 min in a hydrogen-reducing environment. It was shown that an increase in residual Ni content in the surface coating noticeably lowered the interfacial contact resistance and raised the corrosion resistance, depending on the remaining nickel content and the thickness of the surface coatings. In support of the XPS depth profile, this was ascribed to the relative enrichment of the Ni element and the detectable reduction of oxygen content in the coating, which could be associated with the significant evaporation of acrylic resin that occurred during thermal treatment. The optimum Ni composition in the resultant coating film, achieved through the addition of 15 wt.% NiSO₄·6H₂O to the acrylic resin and CrO₃ solution, was estimated to be about 10 wt.%.     

从铜冶炼烟气酸洗液中分离富集铼

铜冶炼烟气酸洗液经D296阴离子交换树脂吸附后,再依次采用氨水解吸Sb,NaOH和酒石酸混合溶液解吸Bi,NH₄SCN溶液解吸Re,实现Re/Sb/Bi的分步解吸并获得铼富集液。结果表明：酸洗液电位对Re、Sb、Bi吸附率没有明显影响,适宜的酸洗液H₂SO₄浓度为43.81 g·L^-1,Re、Sb、Bi吸附率分别为100%、6.55%和89.05%;D296树脂吸附Re的穿透容量和饱和容量分别为1.308和1.773 g·L^-1,且树脂利用率为73.77%;先采用12.5%氨水解吸Sb,16%NaOH+140 g·L^-1酒石酸混合溶液解吸Bi,通过添加酒石酸可有效抑制Bi水解,再采用10%NH₄SCN溶液解吸Re,得到铼富集液,其Cu、As、Sb、Bi浓度均降至1 mg·L^-1以下,且使酸洗液中Re富集了4倍。     

Long-range magnetic order displayed by a bimetallic pentanuclear cluster complex [(Ni(2,2′-bipy)2)3(Fe(CN)6)2]·13H2O and by a Cu(II) analog

A bimetallic pentanuclear cluster complex contains three bis(2,2′-bipyridine)nickel(II) moieties bridged, through two vacant cis-positions around each nickel, to two separate hexacyanoferrate(III) groups via NiNCFe linkages. Freshly prepared crystals of this compound contain 17 water and two dimethylformamide molecules of solvation per cluster. Loss of some solvent molecules is rapid in air, the resulting ‘partly desolvated’ material showing intracluster ferromagnetic coupling and a S=4 ground state, but without long-range magnetic order. In contrast, a rapidly precipitated powder sample, containing 13 waters of hydration [(Ni(2,2′-bipy)₂)₃(Fe(CN)₆)₂]·13H₂O, displays long-range order at a T_C of 11 K. Inter-cluster interactions occur via the H-bonded water pathways which join neighbouring Fe(CN)₆³⁻ groups in separate clusters. Thus, a new example of inter-cluster magnetic ordering has been achieved. A copper(II)-bipy analog also shows long-range order, with T_C of 13 K. In the absence of a crystal structure, the magnetic and spectral properties of this Cu derivative point to a different structural topology being present.     

Study of the feasibility of producing Al–Ni intermetallic compounds by mechanical alloying

Mechanical alloying (MA) was employed to synthesize Al–Zn–Mg–Cu alloys of high weight percentage of the nickel component from the elemental powders of constituents via high-energy ball milling. The mixed powders underwent 15 h of milling time at 350 rpm speed and 10: 1 balls/powder weight ratio. The samples were cold-compacted and sintered thereafter. The sintered compacts underwent homogenization treatments at various temperatures conditions and were aged at 120°C for 24 h (T6). The milled powders and heat-treated Al alloy products were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The crystallite sizes and microstrains of the alloyed powder were estimated via measuring the broadening of XRD peaks using the Williamson–Hall equation. The results have revealed that optimum MA time of 15 h has led to the formation of Al-based solid solutions of Zn, Mg, Cu, and Ni. The outcomes showed that the Vickers hardness of the sintered Al–Zn–Mg–Cu compacts of Ni alloys was enhanced following aging at T6 tempering treatments. Higher compression strength of Al-alloys with the addition of 15% nickel was obtained next to the aging treatment.     

Desorption and reactions between alcohols adsorbed on Na-Zr-M phosphates and a compensator ion M = Cu2+, Ni2+, Co2+

Thermal desorption and reactivity of isopropanol and isobutanol adsorbed on ternary sodiumzirconium orthophosphates M-NZP with ions M²⁺ = Cu, Ni, Co partially substituting sodium ions is studied. The adsorption sites of isopropanol and its dehydration are shown to differ in terms of kinetic order. Desorption and reaction orders are identical for isobutanol. The activation energy of isopropanol desorption increases for the series Ni (92) > Co (125) > Cu (167) as a linear function of their ionic radii. The activation energy of isobutanol desorption is 40–65 kJ/mol.     

Effect of nanocrystalline grain size on the electrochemical and corrosion behavior of nickel

Nanocrystalline nickel of different grain sizes (8–28 nm) was produced by electrodeposition using Watt's bath. Saccharine addition to the bath and pulsed current deposition were effective in lowering the grain size of the deposits. The grain size and microstrain of deposits was determined by X-ray diffraction analysis. The microhardness of nanocrystalline Ni ranged between 572 and 724 kg/mm². The electrochemical behavior of nanocrystalline Ni was evaluated in 1 mol/l H₂SO₄ and compared with that of coarse-grained nickel. All the nickel samples exhibited active–passive potentiodynamic polarization behavior. The zero current potential, passive current density and breakdown potential generally increased with decrease in grain size. The increased passive current density for nanocrystalline nickel confirmed the defective nature of passive film that forms on nanocrystalline nickel. The tendency for localized corrosion was lower in case of nanocrystalline nickel as indicated by increased breakdown potential. Tafel and linear polarization tests revealed that the corrosion rate of freshly exposed surfaces of Ni decreased with grain size, thereby indicating greater hindrance to anodic dissolution in nanocrystalline Ni. The magnitude of compressive microstrain in the Ni deposits increased with decrease in grain size.     

Effect of nickel with chromium on microstructure and toughness of heat affected zone in low carbon steel

Abstract

In the present work, the effects of nickel with chromium and of varying heat input on the microstructure and toughness of the grain coarsened heat affected zone (GCHAZ) of a low carbon steel were investigated. In the welding experiments, low carbon steel specimens having five different combinations of nickel and chromium content (0·9Ni–0·3Cr, 1·9Ni–0·8Cr, 2·8Ni–1·3Cr, 3·8 Ni–1·7Cr, and 4·9Ni–2·1Cr, all wt%) were welded using a submerged arc welding process with heat inputs of 0·5, 1, and 2 kJ mm^-1. Following welding, the microstructure, hardness, and toughness of the GCHAZs were investigated. From the results, attempts were made to establish a relationship between heat input, nickel and chromium contents, microstructure, hardness, and toughness of the GCHAZ. Charpy impact testing and microstructural observation showed that, for a heat input of 0·5 kJ mm^-1, nickel plus chromium contents in the range 1·9Ni–0·8Cr to 4·9Ni–2·1Cr promoted the formation of martensite, thereby producing lower toughness values. It was subsequently found that, taking into consideration the microstructure, hardness, and toughness of the GCHAZ, an intermediate heat input (1 kJ mm^-1) gave higher toughness values for all nickel and chromium contents. However, it was observed that satisfactory toughness values could not be obtained by varying the heat input for the 3·8Ni–1·7Cr and 4·9Ni–2·1Cr steels.     

Pretreatment-free Ni−P plating on magnesium alloy at low temperatures

Electrochemically promoted electroless plating (EPEP) was used for the application of pretreatment-free Ni?P coating on AM60B magnesium alloy at low temperatures and the obtained coating was characterized by SEM, AFM, EDS and XRD techniques. Compact, uniform, and medium-phosphorus Ni?P coating with mixed crystalline?amorphous microstructure was obtained by applying a cathodic current density of 4 mA/cm² at 50 °C. Also, island-like nickel clusters were deposited on the alloy surface under the same plating condition but without applying the cathodic current. In addition, the durability of the magnesium alloy against corrosion was strongly improved after plating via EPEP technique which was revealed by electrochemical examinations in 3.5% NaCl (mass fraction) corrosive electrolyte. The results of the electrochemical examinations were confirmed by microscopic observations. Thickness, microhardness, porosity and adhesive strength of the deposits were also qualified.     

离子交换膜电解槽中电沉积金属镍(英文)

对离子交换膜电解槽中电沉积金属镍的条件进行优化。研究镍(II)及硼酸浓度、pH及温度对电沉积镍的电流效率和能耗的影响。电解槽阴极液为含硼酸的硫酸镍溶液,阳极液为硫酸溶液。采用阴离子交换膜将阴、阳极室隔开,同时维持极室间的导电性。结果表明:阴极电流效率随镍和硼酸浓度以及pH值的增加而提高,随电流密度和搅拌速率的增大而降低。得到的优化电解条件为:Ni40g/L、硼酸40g/L、温度42oC、pH6、阴极电流密度300A/m2。在该条件下的电流效率为97.15%。     

Electrical conductivity and molecular properties of organodithioheterobimetallics [PhHg]2[M(dithio)2] {M=Ni, Cu or Zn; dithio=isomaleonitriledithiolate (i-MNT) 1,1-dicarboethoxy-2,2-ethylenedithiolate (DED) or trithiocarbonate (CS3)}

Organoheterobimetallic compounds of the type, [PhHg]₂[M(dithio)₂] {M=Ni(II), Cu(II) or Zn(II); dithio=isomaleonitriledithiolate (i-MNT²⁻), 1,1-dicarboethoxy-2,2-ethylenedithiolate (DED²⁻) or trithiocarbonate (CS₃²⁻)} have been synthesized and investigated by molecular spectroscopies and conductivity techniques. Magnetic behaviour, together with electronic spectra, are compatible with square planar coordination geometry around nickel(II) in [PhHg]₂[Ni(dithio)₂]. Magnetic moments, 1.6 BM and 1.25 BM for [PhHg]₂[Cu(i-MNT)₂] and [PhHg]₂[Cu(DED)₂] showed involvement of some sort of Cu–Cu interaction. Their electronic and EPR spectra show distorted square planar geometry with tetragonal/rhombic symmetry around copper(II). Powder X-ray diffraction patterns of the complexes have been compared. All the complexes show σ_rt in 2.29×10⁻¹⁰−4.38×10⁻⁴ S cm⁻¹ range. [PhHg]₂[Ni(DED)₂] and [PhHg]₂[Cu(i-MNT)₂] show semiconducting behaviour as their conductivity increases with increase in temperature with band gaps 0.39 eV; 0.57 eV and 2.38 eV, respectively.     

The use of cement kiln dust for the removal of heavy metal ions from aqueous solutions

Abstract

The possibility of removal and utilisation of heavy metal (HM) ions from aqueous solutions by cement kiln dust (CKD) has been studied. The experiments have shown that CKD may be used for industrial wastewater decontamination. They revealed that CKD may be used for neutralisation of acidic wastewaters (alkalinity 12–16 meq g^?1) and for removal of HM ions such as Cu(II), Ni(II), Pb(II), Cd(II) and Co(II). CKD acts as an alkaline agent and sorbent. The main crystalline components of CKD are: calcite, CaCO₃ (80% by mass), 10–15% SiO₂ and the remainder is basic calcium silicate, Ca₅(SiO₄)₂(OH)₂. The maximal capacity of CKD to remove Cu(II) is 0·29 g g^?1 CKD (9·1 meq g?1); Ni(II), 0·14 g g^?1 CKD (4·7 meq g^?1); Pb(II), 2·0 g g^?1 CKD (19 meq g^?1); Cd(II), 0·42 g g^?1 CKD (7·4 meq g^?1); and Co(II), 0·20 g g^?1 CKD (6·8 meq g^?1). Interaction of CKD with Cu(II) ions produces devillite Cu₄(CaSO₄)₂(OH)₆·3H₂O, with Pb(II) – basic carbonate Pb₃(CO₃)₂(OH)₂ and with Cd(II) ions – Cd(OH)Cl. The products of interaction of CKD with Ni(II) and Co(II) ions are amorphous: apparently hydrated Ni(OH)₂ and Co(OH)₂.     

Very rapid growth of aligned carbon nanotubes on metallic substrates

Aligned carbon nanotubes were grown on metallic substrates using a microwave plasma-enhanced chemical vapor deposition system. The substrates were Ni and Cu, and the catalyst was an Fe–Si alloy thin film. The effects of substrate and catalyst characteristics and growth temperature were studied. We show, via the use of a microwave shield, and with optimized catalyst thickness and growth temperature, that carbon nanotubes (CNTs) with a length of up to 2.15 mm and an unprecedently high growth rate of 177 μm min^?1 can obtained. Non-isothermal growth was performed to investigate the growth kinetics and therefore to obtain the activation energies of CNTs grown on Ni and Cu. Very similar activation energies for the growth of CNTs on Ni and Cu substrates were determined to be 101.5 (1.05 eV) kJ mol^?1 and 102.3 (1.06 eV) kJ mol^?1, respectively.