Specific Surface Area Of Cu Research Articles

Synthesis of Microspheres Printed with Metals and Investigation of Their Detection Performance Against Some Metals by ICP-OES

In this study, ion-imprinted polymers were prepared. These polymers can be used for the selective removal of Cu(II) ions from aqueous solutions. To this end, (E)-2-hydroxy-5-((vinylphenyl)diazonyl) benzaldehyde was used as a functional monomer in the synthesis stage of the polymeric adsorbent. Cu(II) imprinted poly[Cu(C15H11N2O2)] microspheres have been synthesised by dispersion polymerisation technique through interaction of the template molecule Cu(II) ion with the functional monomer. The specific surface area of Cu(II) imprinted poly[Cu(C15H11N2O2)] microspheres was 374.26 m2/g. The swelling rate was 80%. The maximum adsorption capacity, the optimum pH and the adsorption equilibrium time were determined to be 153.03 mg/g, in the 8-10 range and 30 min, respectively. The relative selectivity coefficients of the imprinted microspheres were found to be 13.09, 57.88, 44.719 and 35.006 for Cu(II)/Ni(II), Cu(II)/Pb(II), Cu(II)/Zn(II) and Cu(II)/Co(II), respectively. These results showed that the Cu(II)-imprinted microspheres were more selective with respect to Cu(II) ions. Reproducibility studies showed that Cu(II) imprinted poly[Cu(C15H11N2O2)] microspheres can be used repeatedly without significant decrease in adsorption capacity.

Synthesis of carbon-encapsulated copper nanoparticles by the electrical explosion of wire method

The synthesis of carbon-encapsulated copper nanoparticles (Cu&C NPs) by the high-productive method of the electrical explosion of wire (EEW) is presented. Copper wire was evaporated by high-energy electrical current pulses. Evaporation of Cu and the consequent condensation of spherical nanoparticles took place in argon with the controlled addition of butane, which provided encapsulation of copper nanoparticles in carbon shells. Carbon was deposited in the form of several graphite layers, which completely covered the surface. The encapsulation diminished the agglomeration of carbon-encapsulated copper nanoparticles (Cu@C NPs) during their condensation and substantially diminished their average diameter. Upon the deposition of about 4 % of carbon, the average diameter of nanoparticles decreased more than three-fold – from 130 to about 40 nm. Simultaneously, the specific surface area of Cu@C NPs increased from 7 to 35 m2/g. The deposited dense and gas tight carbon shells protected the surface of particles from oxidation. It prevented the self-ignition of as-synthesized nanoparticles at the exposure to ambient air and provided stability to oxidation during long-term storage as well.

High‐Mass‐Loading CoNi‐Layered Double Hydroxide Directly Grown on Brush‐like Cu/Carbon Cloth as High‐Areal‐Capacitance Supercapacitor Electrode

AbstractA combination of high mass loading and efficient utilization of electroactive materials is crucial for simultaneously enhancing the energy and power densities of energy storage devices. This is exemplified herein using cobalt nickel layered double hydroxides nanosheets (CoNi‐LDHs) directly grown on copper nanowires (Cu NWs) standing quasi‐vertically on carbon cloth (CC) to yield a multi‐core‐shell CoNi‐LDHs/Cu NWs/CC as the supercapacitor electrode that exhibits a high areal capacitance of 5.55 F cm−2 (corresponding to a gravimetric capacitance of 1209.15 F g−1) at a large current density of 10 mA cm−2. Such superior rate capability is attributed to the high packing density of CoNi‐LDHs in the electrode, benefitting from the large specific surface area of Cu NWs/CC. Additional contribution stems, on the other hand, from the facile charge transfer kinetics resulted from the elimination of binder from the electrode coupled with the mesopores between not only Cu NWs but also CoNi‐LDHs nanosheets, and the macropores between the carbon fiber of CC. Benefitting from such exceptional rate performance is the supercapacitor built on CoNi‐LDHs/Cu NWs/CC as the positive electrode coupled with bismuth subcarbonate (Bi2O2CO3) as the negative electrode capable of delivering outstanding power density of 13.31 mW cm−2 and energy density of 0.35 mWh cm−2.

Study on the formation of 2-pentanone from ethanol over K-CuZrO2 catalysts

AseriesofK-CuZrO2catalysts with different Cu contents were prepared. The catalytic performance and reaction mechanism of 2-pentanone from ethanol condensation were investigated. The structure and properties of the catalysts were studied by N2 sorption, XRD, H2-TPR, CO2-TPD, TEM and XPS. The results showed that when the content of Cu was 9%, the conversion of ethanol reached the maximum (99.5%) due to the strong interaction between CuO and ZrO2 whichpromoted the reduction of CuO and resulted in the largest specific surface area of Cu on the catalyst surface. The selectivity of 2-pentanone reached the maximum (35.0%) because the strongest basicity related to medium-strength basic sites of the catalyst surface were suitable for the condensation reaction. The formation of 2-pentanone on K-CuZrO2 catalyst was speculated on the basis of the analysis of intermediates: ethanol was dehydrogenated to form acetaldehyde. Then, the acetaldehyde was condensed and decomposed to acetone followed by reaction with acetaldehyde to form 2-pentanone.

Highly efficient Cu/anatase TiO2 {001}-nanosheets catalysts for methanol synthesis from CO2

Anatase TiO2 nanosheets (-ns-) with dominant exposed {001} facets were used as support to load copper, and the synthesized Cu/TiO2-ns catalysts were evaluated for CO2 hydrogenation to methanol. Under the reaction conditions, P = 3.0 MPa, T = 260 °C, V(N2):V(H2):V(CO2) = 8:69:23 and gas hourly space velocity (GHSV) = 3600 mL g−1 h−1, the methanol yield reached an appealing high value, 5.6%. Copper-loading amount, calcination temperature and reduction atmosphere have been investigated in this work, which significantly influence the particle sizes of copper and/or the defect concentration in TiO2, then leading to different catalytic performance. Characterizations of XRD, EPR, CO2-TPD and FTIR demonstrate that higher specific surface area of Cu is good for the hydrogenation of CO2 and adequate amount of Ti3+ plays important roles in CO2 activation. Both of them facilitate high turnover frequency (TOF) of methanol formation.

Effect of medium solvents on crystalline degree and specific surface area of Cu<SUB align="right">3BiS<SUB align="right">3 nanoparticles synthesised by biomolecule-assisted hydrothermal and solvothermal methods

Cu3BiS3 nanoparticles were successfully synthesised by hydrothermal and solvothermal methods using L-cysteine biomolecules as a sulphur source and complexing agent. Phase and purity of the samples were characterised by X-ray diffraction (XRD) and selected area electron diffraction (SAED). Scanning and transmission electron microscopy (SEM and TEM) revealed the increasing of particle size from 29.8 ± 6.3 nm to 89.6 ± 17.2 nm by changing the medium solvents from de-ionised (DI) water to ethylenediamine (EN), in accordance with the decrease in the BET surface area from 17.5560 ± 0.1170 m2/g for the DI particles to 4.0297 ± 0.0370 m2/g for the EN particles. The absorption spectrum of highly crystalline Cu3BiS3 nanoparticles synthesised in EN was used to determine the direct energy gap (Eg) which was found to be 1.6 eV. In this research, a formation mechanism is proposed and discussed according to the experimental results.

Hydrogen production from steam reforming of methanol over CuO/ZnO/Al2O3 catalysts: Catalytic performance and kinetic modeling

A series of CuO/ZnO/Al2O3, CuO/ZnO/ZrO2/Al2O3 and CuO/ZnO/CeO2/Al2O3 catalysts were prepared by coprecipitation and characterized by N2 adsorption, XRD, TPR, N2O titration and HRTEM. The catalytic performances of these catalysts for the steam reforming of methanol were evaluated in a laboratory-scale fixed-bed reactor at 0.1MPa and temperatures between 473 and 543K. The results showed that the catalytic activity depended greatly on the catalyst reducibility and the specific surface area of Cu. An approximate linear correlation between the catalytic activity and the Cu surface area was found for all catalysts investigated in this study. Compared to CuO/ZnO/Al2O3, the ZrO2-doped CuO/ZnO/Al2O3 exhibited higher activity and selectivity to CO, while the CeO2-doped catalyst displayed lower activity and selectivity. Finally, an intrinsic kinetic study was carried out over a screened CuO/ZnO/CeO2/Al2O3 catalyst in the absence of internal and external mass transfer effects. A good agreement was observed between the model-derived effluent concentrations of CO (CO2) and the experimental data. The activation energies for the reactions of methanol-steam reforming, water-gas shift and methanol decomposition over CuO/ZnO/CeO2/Al2O3 were 93.1, 85.1 and 116.5kJ·mol−1, respectively.

Metal-immobilized magnetic nanoparticles for cytochrome C purification from rat liver.

Cu(2+) -immobilized magnetic poly(hydroxyethylmethacrylate-N-methacryloyl-(l)-histidinemethylester) (mPHEMAH) nanoparticles were prepared by surfactant-free emulsion polymerization for cytochrome C (cyt C) purification from rat liver. Elemental analysis, atomic force microscopy, zeta sizer, and vibrating sample magnetometer were used to characterize mPHEMAH nanoparticles. In addition to these characterization steps, surface area, average particle size, and size distribution of mPHEMAH nanoparticles were determined. Quantity of immobilized Cu(2+) was measured using atomic absorption spectrophotometry. N-Methacryloyl-(l)-histidinemethylester and Cu(2+) content of mPHEMAH nanoparticles were 0.18 mmol/g polymer and 0.11 mmol/g polymer, respectively. Specific surface area of Cu(2+) -immobilized mPHEMAH nanoparticles was 1180 m(2) /g. Effect of initial cyt C concentration, pH, temperature, and ionic strength on cyt C adsorption onto Cu(2+) -immobilized mPHEMAH nanoparticles was investigated. Maximum cyt C adsorption capacity of Cu(2+) -immobilized mPHEMAH nanoparticles was 311.9 mg/g polymer. Maximum adsorption was obtained at pH 8.0 and 4°C. Cu(2+) -immobilized mPHEMAH nanoparticles were used ten times with 4.1% decrease in adsorption capacity. In the last stage, Cu(2+) -immobilized mPHEMAH nanoparticles were used to purify cyt C from rat liver tissue, and the purity of desorbed fractions was controlled by SDS-PAGE.

Competitive Removal of Heavy Metals from Aqueous Solutions by Montmorillonitic and Calcareous Clays

A batch sorption method was used to study the removal of few toxic metals onto the Late Cretaceous clays of Aleg formation (Coniacian–Lower Campanian system), Tunisia, in single, binary and multi-component systems. The collected clay samples were used as adsorbents for the removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions. Results show that the natural clay samples were mainly composed of silica, alumina, iron and magnesium oxides. N2-adsorption measurements indicated mesoporous materials with modest specific surface area of Cu(II)>Zn(II)>Cd(II) due to the variable physical properties of the studied metals. The maximum adsorption capacity reached 131.58 mg/g in single systems, but decreased to <50.10 mg/g in mixed systems. In single, binary and muti-element systems, the studied clay samples removed substantial amounts of heavy metals, showing better effectiveness than the relevant previous studies. These results suggest that the studied clay samples of the Late Cretaceous clays from Tunisia can be effectively used as natural adsorbents for the removal of toxic heavy metals in aqueous systems.

Electron probe and auger electron microprobe characterization of modified Cu-based amorphous alloys.

Changes in morphology and local chemical composition due to various methods of modification of surfaces of Cu-Zr, Cu-Hf, and Cu-Ti amorphous alloys (caused by aging in air/dry corrosion or hydrogen charging) were investigated. These modification/activation procedures transform the original amorphous ribbons of low surface area into efficient and stable catalysts, due to the segregation of a distinct amount of Cu and the development of a large specific surface area of Cu on a ZrO x or HfO x support. It was found that aging in air resulted in the formation of a bilayer of rough copper (containing small Cu particles indispensable for catalysis) on top of a rather smooth oxide underlayer (ZrO x, HfO x ). Careful examination of the cross sections of the modified Cu-based ribbons revealed that, even after prolonged aging in air, only the first few microns of the surface layer was modified. Cu-Ti alloy was stable in air and did not undergo the expected modification. Hydrogenation followed by air exposure resulted in a disintegration of the ribbons into small pieces. Each piece was covered with many small Cu clusters 0.1-0.5 microm in diameter formed on an oxide underlayer. High-energy resolution Auger spectroscopy allowed identification of the underlayers (ZrO2, HfO2, or TiO x ), identification of small Cu clusters, determination of the degree of surface oxidation of them, and mapping of the surface to identify the Cu-covered and "naked" heavy metal.

Modification of surface activity of Cu-based amorphous alloys by chemical processes of metal degradation

Changes in morphology, local chemical composition, catalytic activity and local surface-enhanced Raman scattering (SERS) activity due to various methods of modification of surfaces of Cu–Zr, Cu–Hf and Cu–Ti amorphous alloys were investigated. Our recent investigations have shown that otherwise detrimental processes of material degradation may help to segregate clusters of Cu and to develop a large specific surface area of Cu on ZrO x or HfO x supports. This transforms the original Cu-based amorphous ribbons of low surface area into efficient and stable catalysts. The following methods of activation based on the degradation processes, and their combinations are presented: ageing/oxidation in air, anodic activation, and pre-treatment with hydrogen (hydrogenation under high hydrogen pressure, or cathodic hydrogen charging). Structural changes in the bulk of the amorphous alloys introduced by the above pre-treatments were examined by XRD. Morphological and chemical changes on the surface were followed microscopically (optical microscopy and high resolution SEM) and by using a high resolution scanning Auger microprobe (SAM) and an X-ray electron microprobe. The amount of segregated Cu on the surface was estimated by an electrochemical method. A test reaction of dehydrogenation of 2-propanol was used to compare the catalytic activity of the materials after different chemical pre-treatments. Proposed mechanisms of changes in the local adsorption properties, local enhancement of Raman spectra and the catalytic activities due to the above combined pre-treatments are discussed.