Electrodeposition of catalytically active nickel-thallium alloy powders from sulphate baths

The electrodeposition of nickel-thallium alloy powder was investigated from acidic sulphate baths containing 0.0125 NiSO₄·6H₂O, 0.005–0.020 Tl Cl, 0.05–0.23 (NH₄)₂SO₄, 0.1 H₃BO₃ and 0.07 mol l^–1 Na₂SO₄ · 10H₂O. The polarization curves, the percentage composition and the current efficiency of the electrodeposited alloy powders were determined as a function of the bath composition. In addition, some properties of the deposits were examined such as the surface morphology, the structure as revealed by X-ray diffraction analysis and the catalytic activity towards the decomposition of 0.4% H₂O₂ solution. The results indicate that the characteristics of the alloy deposition and the properties of the alloy powder are affected to different extents by the bath composition.     

Effects of some plating variables on the electrodeposition of catalytically active nickel-thallium alloy powders

The electrodeposition of nickel-thallium alloy powders was investigated from a selected bath of the composition 0.0125 NiSO₄·6H₂O, 0.01 TICI, 0.10 (NH₄)₂SO₄, 0.10 H₃BO₃ and 0.07 Na₂SO₄·10 H₂O (mol dm^?3). The effects of the pH of the bath, deposition current density and deposition time on the cathodic polarisation, current efficiency and composition of the electrodeposited alloy were determined. The properties of the electrodeposits examined, as a function of the above-mentioned variables, were surface morphology and catalytic activity towards the decomposition of 0.4% H₂O₂ solution. It was found from this investigation that the operating variables influence to a great extent the current efficiency, composition and surface morphology of the electrodeposited alloys; and the catalytic activity is primarily controlled by the surface morphology.     

Electrodeposition of catalytically active Co-Ni-Tl alloy powders from dilute sulphate baths

Cobalt-nickel-thallium alloy powders were electrodeposited from dilute metal sulphate baths of composition: 0.007–0.0245 mol l^–1 CoSO₄·7H₂O, 0.0245–0.007 mol l^–1 NiSO₄·6H₂O, 0.001 mol l^–1 TlCl, 0.5 mol l^–1 (NH₄)₂SO₄, 0.07 mol l^–1 Na₂SO₄·10H₂O and 0.4 mol l^–1 H₃BO₃. The cathodic polarization curves were traced during electrodeposition and utilized in the discussion of a reaction mechanism for the electrolytic powder deposition. The alloy composition and the cathodic current efficiency were influenced to a great extent by the bath composition (I) and slightly by the deposition current density (II). Irrespective of variables (I) and (II), the electrodeposition of the alloy belonged to the anomalous type. The surface morphology and the catalytic activity, towards the decomposition of 0.4% H₂O₂ solution, of the as-deposited alloy powders were affected predominantly by the percentage of cobalt in the alloy. X-ray diffraction studies showed that the alloys consisted mainly of the face-centred cubic nickel phase either alone or with minor proportions of face-centred cubic cobalt phase and hexagonal close-packed -cobalt phase. The occurrence of the latter phases was observed only in the alloys with a higher cobalt percentage than nickel.     

Electrodeposition of cobalt-nickel alloys from ammoniacal single-complex baths

The electrodeposition of cobalt-nickel alloys has been studied from ammoniacal single-complex baths containing 5–50 CoSo₄·7H₂O, 5–50 NiCl₂·46H₂O, 20–50 g dm^?3 (NH₄)₂SO₄ and 250–350 cm³ dm^?3 NH₄OH (20.5% solution). The effects of the plating current density and the concentrations of the bath constituents on the cathodic polarisation, current efficiency and composition of the alloy were investigated. A wide range of alloy compositions with a current efficiency of 60–80% could be obtained from the main baths examined. The alloy plating system interchanged between the normal and the anomalous types depending upon the plating current density and the concentration of NH⁺₄ ion in the bath. Electron microscopic and X-ray diffraction studies proved that the structure of the electrodeposited alloy was controlled by the alloy composition.     

Adsorption of chlorophyll-a from acetone solution on natural and activated bentonite

The adsorption of chlorophyll-a on bentonite desiccated at 110°C, untreated and acid-treated with H₂SO₄ solutions over a concentration range between 0·25 and 2·50 mol dm^?3, from acetone solution at 25°C has been studied. The adsorption isotherms may be classified as using Giles' classification, as type S (untreated sample and 0·25 mol dm^?3 H₂SO₄-treated sample), type H (0·50 mol dm^?3 H₂SO₄-treated sample) and type L (1·00 and 2·50 mol dm^?3 H₂SO₄-treated samples). This fact suggests that the bentonite surfaces (low, high and medium affinity, respectively) behave in differently relation to the adsorption of the chlorophyll-a molecules. The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (K_f) of the samples; K_f values range from 0·43 mg kg^?1 for the untreated bentonite up to 108·89 mg kg^?1 for the 0·50 M H₂SO₄-treated bentonite. The removal efficiencies (R) have also been calculated and range from 5·71% for the untreated bentonite up to 85·18% for the 0·50 M H₂SO₄-treated bentonite.     

Isomer Directed Synthesis of Two 3D Cadmium(II) Compounds: Structure Variation and Energetic Performance

Two inorganic mixtures of copper and sodium compounds have been synthesized and characterized with different measurement techniques. The thermal property of these mixtures has been studied to low temperature up to 223 from 573 K with DSC. The specific heat capacity of this mixture has been measured in atmospheric O₂ at a rate of 10 K min^?1 from 573 to 223 K and vice versa in two thermal cycles. The net specific heat capacity of these mixtures is found endothermic in first and second thermal cycles. The net specific heat capacity of 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂·H₂O; 2NaHSO₄·H₂O (CuPHS) during first thermal cycle is ?71203.05 J kg^?1 K^?1 and in second thermal cycle is ?73881.67 J kg^?1 K^?1 between temperature range of 303–223 K. The net specific heat capacity of mixture 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂; 2Na₂SO₄(CuPS) in first thermal cycle is ?21158.37 J kg^?1 K^?1 and in second thermal cycle is?45739.92 J kg^?1 K^?1 between temperature range of 298–573 K. As both mixtures are endothermic in nature in all cycles, it can be used as heat storage material.The average crystallite size of mixture 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂·H₂O; 2NaHSO₄·H₂O and 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂; 2Na₂SO₄ is ~47 and ~17.3 nm, respectively.     

Preparation and crystallite growth measurement of active magnesium aluminate spinel

MgAl₂O₄ was prepared by cocrystallizing and decomposing Al(NO₃)₃.9H₂O and Mg(NO₃)₂.6H₂O mixture. The crystallite growth of the resulting powder was studied in the temperature range 500 – 1000 °C. It was found that the equation governing the process is D² – D²₀ = KT. Two activation energies for crystallite growth were obtained, 22 kcal and 44 kcal for the temperature ranges 500 – 785 °C and 785 – 1000 °C respectively. It was noted that rapid increase in crystallite size occurred on soaking at a temperature > 800 °C.     

Leaching kinetics of neodymium in sulfuric acid from E-scrap of NdFeB permanent magnet

The leaching kinetics of neodymium in NdFeB permanent magnet powder was analyzed for the purpose of recovery of neodymium in sulfuric acid (H₂SO₄) from E-scrap (electric scrap) of NdFeB permanent magnet powder treated by oxidation roasting to form a reactant. The reaction was conducted with H₂SO₄ concentrations ranging from 2.5 to 3.5M, a pulp density of 110.8 g/L, an agitation speed of 750 rpm, and a temperature range of 30 to 70 °C. After 4 h of leaching, the neodymium content in the E-scrap powders was completely converted into a neodymium sulfate (Nd₂(SO₄)₃) solution phase in H₂SO₄ in the condition of 70 °C and 3.0M H₂SO₄. Based on a shrinking core model with sphere shape, the leaching mechanism of neodymium was determined by the rate-determining step of the ash layer diffusion. Generally, the solubility of pure rare earth elements in H₂SO₄ is decreased with an increase in leaching temperatures. However, the leaching rate of the neodymium in E-scrap powders increased with the leaching temperatures in this study because the ash layer included in the E-scrap powder provided resistance against the leaching. Using the Arrhenius expression, the apparent activation energy values were determined to be 2.26 kJmol^?1 in 2.5M H₂SO₄ and 2.77 kJmol^?1 in 3.0 M H₂SO₄.     

Extraction and Separation of Germanium Using Cyanex 301/Cyanex 923. Its Recovery from Transistor Waste

Abstract

The extraction of Ge(IV) from HCl, HNO₃ and H₂SO₄ media in toluene solution of Cyanex 301 and Cyanex 923 is investigated. It is almost quantitatively extracted (～95%) in Cyanex 301 and Cyanex 923 at 8 molL^?1 HCl but the extractions from H₂SO₄ and HNO₃ are poor in the entire investigated range of acid molarity. Detailed investigations were carried out from HCl medium. Based on the slope analysis data the extracting species is identified as GeCl₄·2R (R=Cyanex 301/Cyanex 923). The extraction of Ge(IV) is higher and comparable in diluents like toluene, n‐hexane and kerosene (160–200°C) and there is no correlation between the dielectric constant and the percent extraction. The extractants are stable towards prolonged acid contact and there is negligible loss in their extraction efficiency even after recycling them for several cycles. The extraction behavior of commonly associated metal ions namely As(V)/(III), Sn(IV), Tl(III), In(III), Ga(III), Fe(III), Al(III), Hg(II), and Cu(II) has also been investigated. Based on the partition data conditions for attaining some binary and ternary separations involving Ge(IV) have been optimized. The separation data have been fused to develop a scheme for the recovery (93%) of pure germanium (～99%) from semi conductor waste.     

Statistical optimization of anticholesterolemic drug lovastatin production by the red mold Monascus purpureus

Lovastatin (HMG-CoA reductase inhibitors), is an important anticholesterolemic drug which inhibits the conversion of HMG-CoA to mevalonate in the biosynthesis of cholesterol. Plackett–Burman statistical screening of 12 media components and subsequent optimization of significant parameters by response surface methodology for the biotechnological production of lovastatin by Monascus purpureus MTCC 369 was studied. In this study, the statistical analysis of Plackett–Burman experimental results showed that the medium components glucose, peptone, MnSO₄·H₂O, NaCl and NH₄Cl as the significant components influencing the lovastatin production. The most significant medium components, glucose, peptone and MnSO₄·H₂O which have confidence level of more than 95% were further optimized using a full factorial central composite design of the response surface methodology. Maximum lovastatin production of 97.5 mg l^?1 was obtained after 14 days of fermentation period in the optimized medium containing, glucose, 52.61 g l^?1 peptone, 16.65 g l^?1; NH₄Cl, 1 g l^?1; KH₂PO₄, 1 g l^?1; yeast extract, 3 g l^?1; K₂HPO₄, 1 g l^?1; KNO₃, 0.5 g l^?1; MgSO₄·7H₂O, 0.2 g l^?1; MnSO₄·H₂O, 0.418 g l^?1; NaCl, 0.5 g l^?1; CaCl₂·2H₂O, 0.1 g l^?1 and FeSO₄·7H₂O, 0.001 g l^?1 at 30 °C and 120 rpm. The production of lovastatin by M. purpureus MTCC 369 in the optimized medium was found to be four times higher than the basal medium in the submerged fermentation. The statistical experimental design serves as an efficient tool for screening large number of variables with minimum number of experiments and optimizing the significant variables for enhancing the production of lovastatin.     

Dilute solution properties of cationic poly(dimethyl sulfate quaternized dimethylaminoethyl methacrylate)

The dilute solution properties of a cationic polyelectrolyte, poly(dimethyl sulfate quaternized dimethylaminoethyl methacrylate) [poly(DMAEM · C₂H₆SO₄)], are studied by measurements of intrinsic viscosity, degree of binding, and flocculation application. The intrinsic viscosity of this polyelectrolyte is related to the type and concentration of added salt. The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. The polyelectrolyte in the presence of KCl has a lower degree of binding, indicating that the proton ion (H⁺) is relatively difficult to bind to the CH₃SO₄^? at the polymer end. The polymerization of DMAEM · C₂H₆SO₄ in 0.5M KCl aqueous solution proceeded more easily than that of DMAEM · C₂H₆SO₄ in pure water. The polymerization rate of DMAEM · C₂H₆SO₄ is found to pass through an extreme value as a function of pH. Optimum flocculation, corresponding to the complete removal of turbidity in the supernatant, is achieved. Beyond the optimum flocculation, high polymer dosages redisperse the bentonite suspensions.     

Effect of cellulose triacetate membrane thickness on forward‐osmosis performance and application for spent electroless nickel plating baths

Cellulose triacetate (CTA) forward‐osmosis (FO) membranes were prepared via the phase inversion method. The influence of thickness on the performance and morphology of CTA FO membranes was discussed in detail. When the thickness of the membrane was 50.0 ± 0.5 μm (CTA4), the prototype CTA membranes displayed a water flux of 20.2 L m^?2 h^?1 and a reverse salt transport of 14.6 g m^?2 h^?1 using 1 mol/L NaCl as the draw solution and deionized water as the feed solution during the FO process at 25 °C. In addition, the high‐performance CTA4 FO membranes have been used to process spent electroless nickel plating baths where the water flux could reach 13 L m^?2 h^?1 and NiSO₄·6H₂O crystals occurred in the feed solution of the spent electroless nickel plating baths. The recovery rates of NiSO₄·6H₂O and water from the spent electroless nickel plating baths were 44.54% and 53.53%, respectively. This study focused on improving membrane design for the FO process and finding a new method of waste liquor or wastewater treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45049.     

Adsorption of cadmium and zinc from aqueous solution on natural and activated bentonite

The adsorption of cadmium and zinc ions on natural bentonite heat-treated at 110°C or at 200°C and on bentonite acid-treated with H₂SO₄ (concentrations: 0·5 mol dm^?3 and 2·5 mol dm^?3), from aqueous solution at 30°C has been studied. The adsorption isotherms corresponding to cadmium and zinc may be classified respectively as H and L types of the Giles classification which suggests the samples have respectively a high and a medium affinity for cadmium and zinc ions. The experimental data points have been fitted to the Langmuir equation in order to calcualte the adsorption capacities (X_m) and the apparent equilibrium constants (K_a) of the samples; X_m and K_a values range respectively for 4·11 mg g^?1 and 1·90 dm³ g^?1 for the sample acid-treated with 2·5 mol dm^?3 H₂SO₄ [(B)-A(2·5)] up to 16·50 mg g^?1 and 30·67 dm³ g^?1 for the natural sample heat-treated at 200°C [B-N-200], for the adsorption process of cadmium, and from 2·39 mg g^?1 and 0·07 dm³ g^?1, also for B-A(2·5), up to 4·54 mg g^?1 and 0·45 dm³ g^?1 [B-N-200], for the adsorption process of zinc. X_m and K_a values for the heat-treated natural samples were higher than those corresponding to the acid-treated ones. The removal efficiency (R) has also been calculated for every sample; R values ranging respectively from 65·9% and 8·2% [B-A(2·5)] up to 100% and 19·9% [B-N-200], for adsorption of cadmium and zinc.     

Potential of integrating Na2SO4 · 10H2O pellets in solar drying system

In the current study, evolution of thermophysical properties of red chilli dried in a mixed mode solar dryer that integrates sodium sulfate decahydrate (Na₂SO₄?·?10H₂O) and sodium chloride (NaCl) as thermal storage were presented. Solar drying with Na₂SO₄?·?10H₂O reduced the drying time by 26.7 and 39%, compared to the drying time with or without NaCl. Dimensional shrinkage was gradual with a nonlinear exponential shape for the whole drying conditions. The evolution of the bulk and particle densities decreased while the porosity of the seed increased with time. The coefficient of heat and mass transfer varied from 0.0036???0.035?W/m²?K to 6.09?×?10^?9???6.2?×?10^?8?m/s, respectively. The thermal conductivity, specific heat capacity, and thermal diffusivity ranged from 0.0568 to 0.1093?W/m?K, 1,072 to 2218.7?J/kg?K, and 4.7?×?10^?5 to 5.13?×?10^?5?m²/s, respectively.     

Black nickel electrodeposition from a modified Watts bath

Black nickel coatings were electrodeposited on to steel substrates from a Watts bath containing potassium nitrate. The best operating conditions necessary to produce smooth and highly adherent black nickel were found to be NiSO₄ · 6H₂O 0.63 M, NiCl₂ · 6H₂O 0.09 M, H₃BO₃ 0.3 M and KNO₃ 0.2 M at pH of 4.6, i=0.5 A dm⁻², T=25 °C and t=10 min. The modified Watts bath has a throwing power (TP) of 61%, which is higher than that reported, not only for nickel, but also for many other metals electrodeposited from different baths. The potentiostatic current–time transients indicate instantaneous nucleation. X-ray diffraction (XRD) analysis shows that the black nickel deposit is pure metallic nickel with Ni(111) preferred orientation.     

Effect of Metallic Coagulant Agents on Oily Wastewater Treatment Performance using Mullite Ceramic MF Membranes

In this paper, the effects of in-line coagulation on permeation flux (PF), fouling resistance (FR), and total organic compound (TOC) rejection (R) of synthesized mullite ceramic membranes during treatment of oily wastewater in coagulation – MF hybrid process were investigated. Four coagulant ((ferrous chloride (FeCl₂.4H₂O), ferrous sulphate (FeSO₄.7H₂O), aluminum chloride (AlCl₃.6H₂O) and aluminum sulphate (Al₂(SO₄)₃.18H₂O)) plus equal concentration of lime in the form of calcium hydroxide (Ca(OH)₂) were evaluated in the coagulation – MF hybrid process at different concentrations (0 ppm, 25 ppm, 50 ppm, and 100 ppm). The results showed that coagulation can affect the membrane filtration by changing characteristics of the oil droplets. Coagulant agents improve the membrane performance at low dosage (25 ppm) for aluminum chloride and mean dosage (50 ppm) for ferrous chloride, ferrous sulphate, and aluminum sulphate. At the best conditions (50 ppm ferrous sulphate), PF increased from 2.22 × 10^?5 to 2.76 × 10^?5 (m³/m² s), FR decreased from 4.2 × 10¹² to 5.55 × 10¹¹ (m^?1), and R increased from 93.8% to 97.1%.     

Cloud Point Extraction and Preconcentration for the Determination of Cu and Ni in Natural Water by Flame Atomic Absorption Spectrometry

Abstract

In this work, a new cloud point extraction (CPE) method was developed for the separation and preconcentration of copper and nickel. The analyte was complexed with 3‐[(8‐{[(E)‐2‐hydroxyimino‐1‐methylpropylidene] amino}‐1‐naphthyl) imino]‐2‐butanone oxime (H₂mdo) in the initial aqueous solution and octylphenoxy polyethoxy ethanol (Triton X‐114) was added as a surfactant. After phase separation, based on the cloud point in the mixture, and dilution of the surfactant‐rich phase with methanol containing 0.1 mol l^?1 HNO₃, the enriched analytes were determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions (i.e. pH=8.5, H₂mdo=3×10^?4 mol l^?1, Triton X‐114=0.1% (w/v)) the enhancement factors of 65 and 59 and detection limits of 0.14 and 0.2 ng ml^?1 were obtained for copper and nickel respectively. The proposed method was applied to the determination of copper and nickel in several natural water samples with satisfactory results.     

Mixtures of potassium sulphate and iron sulphate as catalysts for water vapour gasification of carbon. 1. Kinetic studies

The catalytic activity of K₂SO₄ and FeSO₄ · 5H₂O and mixtures of both sulphates in water vapour gasification has been studied with a PVC model coke. Mixtures of H₂ and H₂O were used at pressures of 0.2, 1 and 2 MPa, a heating rate of 4 K min^?1 and temperatures of 800–910 °C (1 h). Catalyst mixtures of approximately 20 wt% Fe and 80 wt% K (total metal amount 7 wt% of carbon) show an optimum activity, especially in equimolar H₂/H₂O mixtures. Increasing pressure enhances the total gasification rate and significantly increases the CH₄ yield.     

Platinum crystallite size considerations for electrocatalytic oxygen reduction—I

An examination of the activity contributions for atoms at corners, edges and planes of platinum electro-catalyst crystallites was carried out for the reduction of molecular oxygen in 1M H₂SO₄. Varying the mean crystallite diameters between 30 and 400 Å caused at least a 200-fold and 30-fold change in the surface densities of corner and edge sites, respectively. Deliberate sintering of the platinum crystallites caused crystallite growth, with a reduction of surface and lattice defects. The catalysts showed a uniform activity for oxygen reduction of 0·018 ± 0·003 mA/real cm² Pt at 900 mV (nhe) with a Tafel slope of 65 ± 5 mV at 50 and 70°C. Platinum atoms at corners, edges, kink sites or dislocations are not more active than atoms on the crystallite faces for this reaction.     

Charged Membrane Ultrafiltration of Toxic Metal Oxyanions and Cations from Single- and Multisalt Aqueous Solutions

Abstract

With application to the treatment of nonferrous metals production streams, the toxic metals As(V), Se(IV), As(III), and Cd(II) are separated from single-and multisalt aqueous solutions by continuous-flow, membrane ultrafiltration with charged, noncellulosic membranes. The single-salt aqueous solutions of As(V), Se(IV), As(III), or Cd(II) are investigated over pH 5 to 10, metal concentrations in the range 0.5 to 20.0 mM, and transmembrane pressure differences from 2.8 × 10⁵ to 5.6 × 10⁵ N/m², with the effects of these three independent variables established on the metal rejections. The rejections of the monovalent oxyanions H₂AsO₄ ^?, HSeO₃ ^?, and H₂AsO₃ ^? (with sodium as the counterion) are of the order 0.85, and those of the divalent HAsO₄ ^2?, SeO₃ ^2? (and SO₄ ^2?), and of Cd²⁺ are of the order 0.95 for 6.0 mM feed streams. Comparisons are made with the halides, NO₃ ^?, and ClO₄ ^?. The rejection behavior of multisalt solutions of H₂AsO₄ ^? and HSeO₃ ^? is not influenced by the presence of sulfate, but Cd²⁺ produces a decrease in the rejection of Se(IV). For feed streams 2.0 mM each in H₂AsO₄ ^?, HSeO₃ ^?, Cd²⁺, and Zn²⁺ at pH 5, the presence of a high sulfate concentration does not affect the metal rejections, except at greater than 14.0 mM where the Se(IV) rejection begins to decline sharply