Column adsorption of Cu(Ⅱ) by polymer-supported nano-iron oxides in the presence of sulfate: Experimental and mathematical modeling

Polymer-supported hydrous iron oxides (HFOs) are promising for heavy metals removal from aqueous systems.The ubiquitous inorganic ligands,e.g.,sulfate,are expected to exert considerable impacts on pollutants removal by these hybrid sorbents.Herein,we obtained a hybrid sorbent HFO-PS by encapsulating nanosized HFO into macroporous polystyrene (PS) resin.Both batch and column sorption experiments of Cu(Ⅱ) by HFO-PS were carried out in the presence of sulfate.Obviously,the presence of sulfate is favorable for Cu(Ⅱ) sorption onto HFO-PS.The performances of column Cu(Ⅱ) removal were fitted and predicted with Adams-Bohart,Clark,Thomas and BDST models.Thomas model is suggested best-fit to predict the breakthrough curves.Besides,a linear correlation is observed between breakthrough time and column length based on BDST model,which might be useful for predicting the breakthrough time for Cu(Ⅱ) removal by HFO-PS.     

Preparation and sorption studies of microsphere copolymers containing β-cyclodextrin and poly(acrylic acid)

Microsphere polymeric materials containing β-cyclodextrin (β-CD) and poly(acrylic acid) (PAA) with tunable morphologies were prepared in order to improve their sorption characteristics in aqueous solution. The microsphere polymeric materials were prepared using a (water/oil) micro-emulsion-evaporation technique to condense β-cyclodextrin (β-CD) with PAA at various comonomer ratios and mixing speeds. The β-CD microsphere copolymers were characterized using FTIR, TGA, DSC, SEM, elemental (C and H) microanalyses, and solid state ¹³C-NMR spectroscopy. The sorption properties of the polymeric materials at 295 K in aqueous solution containing p-nitrophenol (PNP) were studied using a dye-based method with UV–Vis spectrophotometry at pH 4.6 and 10.3. The sorption isotherms of copolymer/PNP systems were evaluated with various isotherm models (e.g., Langmuir, BET, Freundlich, and Sips). The Sips isotherm showed the best overall agreement with the experimental results and the sorption parameters provided estimates of the sorbent surface area (12.0–331 m²/g) and the sorption capacity (Q_m = 0.359–2.20 mmol/g at pH = 4.6; Q_m = 0.070–0.191 mmol/g at pH = 10.3) for the microsphere copolymer/PNP systems in aqueous solution. The nitrogen adsorption properties of the microporous copolymers in the solid state were obtained at 77K with BET surface areas ranging from 0.275 to 4.47 m²/g. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Zeolite P synthesis based on fly ash and its removal of Cu(Ⅱ) and Ni(Ⅱ) ions

Zeolite P was synthesized through hydrothermal method based on a kind of Class C fly ash(FA). X-ray diffraction(XRD), scanning electron microscopy(SEM), and Brunauer–Emmett–Teller(BET) were used to analyze and characterize the synthetic sample. The kinetics and thermodynamics of copper and nickel ions removed by the zeolite samples were experimentally explored in detail. The results of kinetic treatment showed the second-order exchange second-order saturation model(SESSM) can well describe the removal process of copper ions, while the first-order empirical kinetic model(FEKM) is the best kinetic model for nickel ions. Langmuir and Freundlich isotherms were used to fit the equilibrium concentration of Cu(Ⅱ) or Ni(Ⅱ) under certain conditions. Whether for copper or nickel ion, the Langmuir model is in good agreement with the experimental equilibrium concentration.The apparent theoretical removal capacities for Cu(Ⅱ) and Ni(Ⅱ) can reach to 138.1 mg·g~(-1) and 77.0 mg·g~(-1),respectively.     

Stability of rare earth oxides in a moist environment at elevated temperatures—Experimental and thermodynamic studies: Part II: Comparison of the rare earth oxides

Volatilisation tests enabled to quantify the stability of different rare earth sesquioxides, RE₂O₃ (where RE = Sc, Dy, Er, Yb) and to understand the corrosion process. These tests were carried out at temperatures ranging from 1000 to 1400 °C in moist air with 50 kPa of water at atmospheric pressure, under a flowing gas velocity of 5 cm s^?1. Besides the volatilisation rate, the nature of the volatile gaseous species was determined. The proposed experimental method allowed too to assess the Gibbs free energy of formation of these gaseous volatile species. Finally, the stability of each rare earth oxide under a moist environment at high temperature was compared.     

Facilitated transport separation of propylene–propane: Experimental and modeling study

Supported liquid membrane, as one type of facilitated transport membranes, was used for the separation of propylene–propane mixtures. The effect of trans-membrane pressure and carrier concentration on membrane separation performance were evaluated in terms of mixed-gas selectivity, propylene and propane permeances and propylene and propane permeation fluxes. A general dimensionless model for the transport of components across the membrane was proposed and solved numerically by orthogonal collocation method. Experimental results showed that for a 70:30 (vol.%) propylene–propane mixture, at pressure 120 kPa and carrier concentration 20 wt.%, a propylene permeation flux of 1.46 × 10⁻⁴ mol/m² s was obtained. Mathematical results are in well agreement with experimental results. The average deviation between experimental and modeling results was found to be 5.3% for propylene permeation flux and 0.03% for propane permeation flux.     

Experimental and modeling studies on the enantio-separation of 3,5-dinitrobenzoyl-(R),(S)-leucine by continuous liquid–liquid extraction in a cascade of centrifugal contactor separators

The continuous enantioselective liquid–liquid extraction of aqueous 3,5-dinitrobenzoyl-(R),(S)-leucine (A_R,S) using O-(1-t-butylcarbamoyl)-11-octadecylsulfinyl-10,11-dihydro-quinine (C, a cinchona alkaloid) as extractant in 1,2-dichloroethane (DCE) was studied experimentally in a countercurrently operated pilot scale cascade of six centrifugal contactor separators (CCS) at 294 K. The extractant was efficiently recovered by back-extraction in a single CCS allowing the cascade to be run continuously for 10 h. The steady-state ee of A_R (ee_R) in the raffinate was 42% at a 99% yield, the A_S was obtained with high purity (98% ee_S) and a yield of 55% in the back-extraction raffinate. In total 2.23 g of A_S was obtained at steady-state operation from 8.11 g racemate feed. Deterioration of the ee in time was not observed, demonstrating the robustness of the chemistry. The experiments were modeled using an equilibrium stage approach. The correlation between model and experiment was satisfactory. The model was applied to optimize the production of both enantiomers in >97% ee. At zero reflux, 12 stages are required for 99% ee for both enantiomers. Application of a reflux allows a 25% reduction of the total liquid flow through the system by reduction of the wash feed as well as a reduction in the number of stages from 12 to 11. With a configuration of 12 CINC-V02’s operating at an aqueous feed flow of 360 mL/min, the model predicts that 17.7 kg racemate per week may be separated into both enantiomers with 99% ee using only 60 g of extractant.     

Effect of Cu strike coating on adhesion between Cu–Sn coated steel and rubber

In order to improve the adhesion between steel and rubber, a novel coating deposition technique has been developed, where steel substrate with orchestrated surface roughness was coated with double-layer coatings consisting of a thin Cu strike layer followed by a Cu–Sn layer with varying Sn compositions by immersion route. Coating surface characteristics studied using scanning electron microscope coupled with energy dispersion spectroscopy analyzer, electron probe micro analyzer, and inductively coupled plasma optical emission spectroscopy showed improvement in surface coverage with coating after employing the strike layer coating attributed to the better coating penetration in the deep roughness troughs. Peel test of the coated samples vulcanized with styrene butadiene rubber (SBR) was carried out which showed improvement in adhesion strength of the double-layer-coated samples inferring more uniform Cu-sulfide layer formation at interface due to more uniform coating coverage in these samples. Highest peel strength with uniform cohesive fracture within rubber was observed for optimum 2–3?wt% Sn content in the coatings. This result was further supported by pull-out test conducted on coated wire samples vulcanized with SBR.     

Dispersion of oil droplets in rotor–stator mixers: Experimental investigations and modeling

Forming emulsions by mixing of immiscible liquids, water and silicone oils was carried out by applying the in-line high-shear rotor–stator mixers. In experimental part investigations were carried out using experimental rig consisting of two tanks and an in-line Silverson rotor-stator (150/250) MS; the system was operated in a multiple pass (MP) mode, which can be compared with a single pass (SP) mode experiments. Emulsification of 1 wt.% silicone oils (Dow Corning 200 fluid) with viscosities of 9.4, 48 and 339 mPa s was investigated. Emulsions were stabilized by adding 0.5 wt.% of sodium laureth sulphate. Effects of rotor speed, number of passes and the drop viscosity on the drop size were investigated.Numerical simulations were carried out using the k–ɛ model of turbulence and the multiple reference frame method (MRF) linked to the population balance equation. The population balance was expressed and solved using the quadrature method of moments (QMOM). The breakage kernel for drops whose diameter falls within the inertial subrange of turbulence was defined based on the multifractal model of intermittent turbulence.     

Effect of activation temperature on the surface copper particles and catalytic properties of Cu–Ni–Mg–Al oxides from hydrotalcite-like precursors

The Cu–Ni–Mg–Al oxides catalysts for furfural hydrogenation were prepared from the hydrotalcite-like precursors, and the effect of activation temperature on the Cu⁰ particles and catalytic properties of the catalyst was thoroughly investigated. The catalyst activated by H₂ at 300 °C was found to exhibit the best catalytic activity, due to the presence of the smallest Cu⁰ particles with a high dispersion. Moreover, the bigger Cu⁰ particles were active for furfuralcohol hydrogenolysis to 2-methylfuran in the liquid-phase (ethanolic solution), and the hydrogenation of the furan ring of furfuralcohol and 2-methylfuran on Cu⁰ particles was easily achieved in the vapour-phase.     

Effect of introduction of TiO2 and GeO2 oxides on thermal stability and 2 μm luminescence properties of tellurite glasses

In this paper, Tm³⁺ doped pure tellurite glass, TiO₂ modified tellurite glass and TiO₂/GeO₂ co-modified tellurite glasses were prepared. The effects of the introduction of TiO₂ and GeO₂ oxides on the thermal, structural, optical properties of tellurite glasses were compared and analyzed intensively. Besides, the Judd-Ofelt intensity parameters and absorption and emission cross sections were calculated. DTA curves indicated the thermal stability of pure tellurite glass enhance obviously by GeO₂ modification. The introduction of TiO₂ and GeO₂ oxides in tellurite glasses arise a series of variation on the absorbance, luminescence peak position and fluorescence intensity which have been explained and analyzed in detail. Based on the analysis, the addition of TiO₂ in tellurite glass contributes to the improvement of 2 μm fluorescence performance, and the introduction of GeO₂ has great advantages in enhancing the thermal stability of glass.     

Conversion of syngas to hydrocarbons in a tube-wall reactor using CoFe plasma-sprayed catalyst: experimental and modeling studies

Catalyst activity and product selectivity studies of the conversion of synthesis gas to various hydrocarbon fractions were performed in a single-tube tube-wall reactor (TWR) using a CoFe plasma-sprayed catalyst with the operating conditions: temperature 250–275°C, pressure 0.1–1.03 MPa, exposure velocity 139–722 μms⁻¹, and a H₂:CO ratio of 2.0. The catalyst activity in terms of CO conversion was highest (98.5% m/m) at an exposure velocity of 139 μms⁻¹, temperature of 275°C, and in the pressure range 0.69–1.03 MPa. The selectivity to hydrocarbons was 43–50% (m/m) in the pressure range 0.69–1.03 MPa whereas the selectivity to C₅ + hydrocarbons was over 40% of the total hydrocarbons produced. The production of propylene was higher than ethylene under similar process conditions. The performance of the TWR was predicted by a numerical model. The model is based on the complete two-dimensional transport equations and reaction rate equations, developed for the CoFe catalyst. Predictions are made for the temperature along the axis of the reactor, for CO and H₂ conversions as functions of the reactor length and the exposure velocity, and the axial H₂O and CO₂ concentrations.     

Stability of rare earth oxides in a moist environment at high temperatures—Experimental and thermodynamic studies. Part I: The way to assess thermodynamic parameters from volatilisation rates

A methodology based on a weight loss measurement was used to quantify the volatility of yttria in high temperature water vapor. This method was first assessed on silica. Sintered materials with a shape of pellets were exposed at temperatures between 1000 and 1400 °C in air with 50 kPa of water at atmospheric pressure, under a flowing gas velocity of 5 cm s^?1. Besides the volatilisation rate, the nature of the volatile gaseous species was determined using a kinetic study. Knowing the nature of flows in the furnace, partial pressures of yttrium (oxy-)hydroxide in equilibrium over Y₂O₃ were calculated, and used to assess the enthalpies of formation of YO(OH) and Y(OH)₃.     

Effect of pH and current density on the electrodeposition of Zn–Ni–Fe alloys from a sulfate bath

An investigation was done on the influences of current density and pH on the electrodeposition behavior of Zn?CNi?CFe alloys using a sulfate bath. The bath consisted of 0.1?M ZnSO₄, 0.1?M NiSO₄, 0.1?M FeSO₄, 0.2?M Na₂SO₄, 0.2?M H₃BO_3, and 0.01?M H₂SO₄. The results of Zn?CNi?CFe alloys?? codeposition revealed that the significant inhibition of Ni and Fe deposition takes place because of the presence of Zn²⁺ in the plating bath. A transition current density was noticed above wherein a transition from normal to anomalous deposition took place. Bright and uniform surface appearance deposits of Zn?CNi?CFe were the results obtained at pH range 2?C5, and the deposits showed high corrosion resistance. During the investigation, the usage of cyclic voltammetry and galvanostatic techniques for electrodeposition were utilized, while linear polarization resistance and anodic linear sweeping voltammetry techniques were used for the corrosion study. Characterization of morphology and the chemical composition of the deposits were performed by means of scanning electron microscopy and atomic absorption spectroscopy.     

Effect of pH,ionic strength,foreign ions,humic acid and temperature on Zn(II) sorption onto γ-Al2O3

The sorption of Zn(II) on γ-alumina was investigated as a function of contact time, pH, ionic strength, foreign ions, solid amount, humic acid (HA) and temperature by using batch technique. The results indicated that the sorption of Zn(II) onto γ-alumina was strongly dependent on pH and ionic strength. The sorption of Zn(II) increased slowly with increasing pH at pH 2–5, then increased sharply with pH increasing from 5 to 8.5, and at last maintained a maximum value at pH>8.5. A positive effect of HA on Zn(II) sorption was found at pH<7, whereas a negative effect was observed at pH>7. The thermodynamic data (ΔG⁰, ΔS⁰, ΔH⁰) were calculated from the temperature-dependent sorption isotherms, and the results suggested that the sorption of Zn(II) on γ-alumina was endothermic and spontaneous. The sorption results revealed that the γ-alumina can be as a cost-effective sorbent for pre-concentration of Zn(II) from large volumes of aqueous solutions in environmental pollution cleanup.     

Effect of Polyethylene Glycol (PEG) Powder on Compressibility and Microstructural Properties of Sintered α-Alumina

This study examines the effect of various contents of polyethylene glycol (PEG) powders on density, compressibility, and microstructural properties of sintered α-alumina samples. Moreover, the effect of compaction pressure on the green density of the compacts is studied by applying different pressures ranging from 400 to 550 MPa. Samples were prepared by mechanical blending of alumina and various amounts of PEG powders in a Turbula mixer. The binder contents vary from 1 wt.% to 4 wt.%. The as-prepared mixture was compacted in a universal machine at room temperature under the pressure of 6 MPa to produce disk-shaped samples in a pre-compaction step. Experimental results revealed that adding various amounts of PEG powders has a detrimental effect on the green density of alumina pellets and decreases the green density from 1.95 to 1.87 g/cm³. The results also show that sintered density of samples increased by increasing the compaction pressure to pressures higher than 400 MPa. It is observed that a sudden increase in green density has been observed between 450 and 550 MPa.