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1.
Rasoul Khosravi Ahmad Zarei Mohsen Heidari Ali Ahmadfazeli Mehdi Vosughi Mehdi Fazlzadeh 《Korean Journal of Chemical Engineering》2018,35(4):1000-1008
This study considers the feasibility of uptake of cephalexin, an emerging contaminant, from aqueous solutions by using green local montmorillonite (GLM), montmorillonite coated with ZnO (ZnO/GLM) and montmorillonite coated with TiO2 (TiO2/GLM) in the presence of H2O2. Batch adsorption experiments were carried out as a function of pH, initial concentration of the cephalexin, adsorbent dosage, contact time, and temperature. Finally, the adsorbents were characterized by XRD, SEM and FTIR analyses. XRD patterns showed dramatic changes in the adsorbents after loading with the nanoparticles, confirming successful placing of the nanoparticles onto GLM. The GLM mineral surface after nanoparticle loading appears to be fully exposed and more porous with irregular shapes in particles diameters of 1-50 microns. FTIR analyses also confirmed dramatic changes in surface functional groups after modification with these nanoparticles. The results showed that the removal efficiency of cephalexin was better at lower pH values. Totally, the removal efficiency increased with increase in adsorbent dosage and contact time and decreased with concentration and temperature increase. The thermodynamics values of ΔG o and ΔH o revealed that the adsorption process was spontaneous and exothermic. In isotherm study, the maximum adsorption capacities (qm) were obtained to be 7.82, 17.09 and 49.26 mg/g for GLM, ZnO/GLM and TiO2/GLM, respectively. Temkin constant (B T ) showed that adsorption of cephalexin from solution was exothermic for all three adsorbents. 相似文献
2.
R. S. Bubnova J. E. Anderson M. G. Krzhizhanovskaya S. K. Filatov 《Glass Physics and Chemistry》2010,36(3):369-375
Anhydrous ammonium pentaborate NH4B5O8 has been synthesized by thermal dehydration of larderellite NH4[B5O7(OH)2] · H2O at a temperature of 290°C for 7 h. The crystal structure has been determined from the X-ray powder diffraction data: a = 7.58667(5) Å, b = 12.00354(8) Å, c = 14.71199(8) Å, R p = 6.23, R wp = 7.98, R B = 12.7, R F = 8.95, and β-KB5O8 structure type. The double interpenetrating framework is formed by pentaborate groups, each consisting of a boron-oxygen tetrahedron and four triangles, in which all oxygen atoms are bridging. The thermal behavior of the NH4B5O8 compound has been investigated using thermal X-ray diffraction. As for other pentaborates of this type, the thermal expansion of the NH4B5O8 compound is anisotropic and reaches a maximum along the a axis. The thermal expansion coefficients are as follows: α a = 39 × 10?6, α b = 6 × 10?6, α c = 20 × 10?6, and α V = 65 × 10?6 °C?1. 相似文献
3.
It is difficult to research on the surface structure of amorphous phase in fly ash during leaching reaction due to crystalline phase and complex structure. In the present work, in order to reveal the effects of leaching reaction on the surface structure of amorphous phase in fly ash, the modelling CaO-Fe2O3-Al2O3-SiO2 glass was prepared by the traditional melting methods. The leaching reaction of CaO-Fe2O3-Al2O3-SiO2 glass with 7.5 M KOH was investigated by spectroscopy, spectrophotometer and wet chemical method. The results show that the content of Q 1, Q 2, Q 3 and Q 4 of glass without corrosion was 4.21, 9.51, 23.03 and 52.55%, respectively, which shows that the network polymerization of glass is compact. The leaching reaction of glass can be described by the following equation: dS/dt = k/(r + S 0). Leaching in KOH for various times induces the content of Q 4 and Q 1 to be decreased, and Q 2 and Q 3 increased, resulted in the depolymerization of network and the surface glass dissolved in alkaline solution to form a gel phase. In stage one of leaching reaction, the rate of iron ion leached from glass surface was slow, which resulted in the small slope of straight-line relationship of leaching curve. In the following stage, the leaching rate of iron ion increased with the prolongation of time. 相似文献
4.
The density d at a temperature of 25°C is measured by the hydrostatic weighing method, the Vickers microhardness H V is determined, and the fluctuation free volume fraction f g is calculated for glasses in the SrO-B2O3-SiO2 system with a constant strontium oxide content in the range from 35 to 45 mol %. It is demonstrated that the quantities H V and f g decrease and the density d increases with an increase in the SrO content. 相似文献
5.
The crystal structure of Pb6O[(Si6Al2)O20)] is investigated using X-ray diffraction. The compound has tetragonal symmetry, space group I4/mmm, a = 11.7162(10) Å, c = 8.0435(12) Å, and V = 1104.13(2) Å3. The structure is refined to R 1 = 0.036 for 562 unique reflections with [F 0] ≥ 4σF. The structure contains two symmetrically independent positions of the Pb2+ cations coordinated by five O atoms (Pb2+-O2? = 2.34–2.68 Å). The TO4 tetrahedra (T = Si, Al) form tubular [(Si6Al2)O20] chains extended along the c axis. The O4 oxygen atom is not bonded to the Si and Al atoms and is octahedrally coordinated by six Pb atoms with the formation of an oxo-centered OPb6 octahedron. The assumption is made that, in some of lead silicate and aluminosilicate glasses, a number of oxygen atoms are located outside the tetrahedral structure and represent segregation centers of the Pb2+ cations due to the formation of oxo-centered complexes. 相似文献
6.
The geometrical and topological analysis of the crystal structure of intermetallide Na44Tl7 (Na6Tl, a = 24.154 Å, V = 14091.8 Å3, space group F-43m) is carried out. The algorithms of the combinatorial-topological analysis, which ensure the recovery of the symmetrical and topological code (program) of the cluster self-assembly of the crystal structure of an intermetallide, are developed. The topological type of the basic 3D network for two types of cluster precursors corresponds to a simple cubic 3D network P c with CN = 6 and basic 2D network of type 44. There are eight cluster precursors in the unit cell: four K86 and four K50. The cluster precursor K86 made from 86 atoms is formed from eight icosahedra i-TlNa12 linked by the apices. The center of the cluster precursor K86 is at the position 4a (0, 0, 0) with the point symmetry g = –43m. The 50-atomic cluster precursor K50 consists of six i-TlNa12 icosahedra. The center of the cluster precursor K50 is in the partial position 4b (0, 0, 0) with the point symmetry g = –43m. The symmetrical and topological codes of the self-assembly of 3D structures from nanocluster precursors K86 and K50 are reconstructed in the following form: primary chain → microlayer → microframework. 相似文献
7.
Reduced Cu/ZnO catalyst was synthesized through solid phase grinding of the mixture of oxalic acid, copper nitrate and zinc nitrate, followed by subsequent calcination in N2 atmosphere without further H2 reduction. The catalysts were characterized by various techniques, such as XRD, TG-DTA, TPR and N2O chemisorption. Characterization results suggested that during the calcination in N2, as-ground precursor (oxalate complexes) decomposed to CuO and ZnO, releasing considerable amount of CO, which could be used for in situ reduction of CuO to Cuo. The in situ reduced O/I-Cu/ZnO catalyst was evaluated in CO2 hydrogenation to methanol, which exhibited superior catalytic performance to its counterpart O/H-Cu/ZnO catalyst obtained through conventional H2 reduction. The decomposition of precursor and reduction of CuO happened simultaneously during the calcination in N2, preventing the growth of active Cu0 species and aggregation of catalyst particles, which was inevitable during conventional H2 reduction process. This method is simple and solvent-free, opening a new route to prepare metallic catalysts without further reduction. 相似文献
8.
Hongmei Xie Qinxiang Du Hui Li Guilin Zhou Shengming Chen Zhaojie Jiao Jianmin Ren 《Korean Journal of Chemical Engineering》2017,34(7):1944-1951
Ce1?x Cu x O2 oxide solid solution catalysts with different Ce/Cu mole ratios were synthesized by the one-pot complex method. The prepared Ce1?x Cu x O2 catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H2 temperature-programmed reduction (H2-TPR). Their catalytic properties were also investigated by catalytic combustion of phenyl volatile organic compounds (PVOCs: benzene, toluene, xylene, and ethylbenzene) in air. XRD analysis confirmed that the CuO species can fully dissolve into the CeO2 lattice to form CeCu oxide solid solutions. XPS and H2-TPR results indicated that the prepared Ce1?x Cu x O2 catalysts contain abundant reactive oxygen species and superior reducibility. Furthermore, the physicochemical properties of the prepared Ce1?x Cu x O2 catalysts are affected by the Ce/Cu mole ratio. The CeCu3 catalyst with Ce/Cu mole ratio of 3.0 contains abundant reactive oxygen species and exhibits superior catalytic combustion activity of PVOCs. Moreover, the ignitability of PVOCs is also affected by the respective physicochemical properties. The catalytic combustion conversions of ethylbenzene, xylene, toluene, and benzene are 99%, 98.9%, 94.3%, and 62.8% at 205, 220, 225, and 225 °C, respectively. 相似文献
9.
S. A. Petrov O. Yu. Sinel'shchikova L. F. Grigor'eva I. B. Patrina N. O. Ovchinnikov V. V. Gusarov 《Glass Physics and Chemistry》2005,31(6):803-807
The ramsdellite-type phases crystallizing in the Li2O-Fe2O3-TiO2 system in the course of synthesis in gaseous media at different oxygen partial pressures are studied. Solid solutions based on the ramsdellite structure with the composition Li2Ti3?xFe x O7 ? δ (0 ≤ x ≤ 0.7) are prepared in an oxidizing medium (PO2 = 1 atm) for the first time. Analysis of the results obtained by electron paramagnetic resonance and Mossbauer spectroscopy revealed that, in these solid solutions, all iron ions are in the oxidation state Fe+3. 相似文献
10.
Yu. N. Ushakova L. A. Kalinina I. S. Yurlov E. G. Fominykh B. A. Ananchenko A. A. Rossikhina I. V. Murin 《Glass Physics and Chemistry》2007,33(4):369-378
The solid-solution regions in the MeSm2S4-MeS and MeSm2S4-Sm2S3 (Me = Ca, Ba) systems are revealed. The average ion, cation, and anion transport number of the synthesized solid electrolytes xSm2S3[Ca(Ba)S] · (100 ? x)Ca(Ba)Sm2S4 (x = 1?10 mol %) are determined by the electromotive force (emf) method with the use of concentration cells with and without transfer. In the phases under investigation, the ion transfer in the temperature range 673–723 K is provided by sulfide ions (\(t_{S^2 } \) = 1.00±0.02). The diffusion coefficients of S2? ions in the solid electrolytes are determined by potentiostatic chronoamperometry. A vacancy mechanism of defect formation is proposed. It is demonstrated that the transport characteristics of the solid electrolytes based on the CaSm2S4 compound are worse than those of the solid electrolytes based on the BaSm2S4 compound. 相似文献
11.
Thien An Le Tae Wook Kim Sae Ha Lee Eun Duck Park 《Korean Journal of Chemical Engineering》2017,34(12):3085-3091
The effect of alumina crystalline phases on CO and CO2 methanation was investigated using alumina-supported Ni catalysts. Various crystalline phases, such as α-Al2O3, θ-Al2O3, δ-Al2O3, η-Al2O3, γ-Al2O3, and κ-Al2O3, were utilized to prepare alumina-supported Ni catalysts via wet impregnation. N2 physisorption, H2 chemisorption, temperature-programmed reduction with H2, CO2 chemisorption, temperature-programmed desorption of CO2, and X-ray diffraction were employed to characterize the catalysts. The Ni/θ-Al2O3 catalyst showed the highest activity during both CO and CO2 methanation at low temperatures. CO methanation catalytic activity appeared to be related to the number of Ni surface-active sites, as determined by H2-chemisorption. During CO2 methanation, Ni dispersion and the CO2 adsorption site were found to influence catalytic activity. Selective CO methanation in the presence of excess CO2 was performed over Ni/γ-Al2O3 and Ni/δ-Al2O3; these substrates proved more active for CO methanation than for CO2 methanation. 相似文献
12.
A cathode material for lithium-ion batteries–LiNi1/3Co1/3Mn1/3O2–was prepared by solution combustion synthesis and characterized by XRD, SEM, and galvanostatic charge/discharge cycling. The sample calcined at 950°C for 10 h showed best charge/discharge performance. An initial discharge capacity (C) of 150.5 mA h g–1 retained 95.7% of its value after 75 charge/discharge cycles at Ic = 14 mA g–1 (0.2C rate), Id = 70 mA g–1 (0.5C rate). 相似文献
13.
A new compound, CdPb2O2Cl2, is synthesized by the method of solid-phase reactions. The compound has monoclinic symmetry, space group C2/m, a = 12.392(8) Å, b = 3.8040(14) Å, c = 7.658(5) Å, β = 122.64(5)°, and V = 304.0(3) Å3. The structure contains one symmetrically independent position of the Pb2+ cation coordinated by three O2? anions (Pb2+-O2? = 2.29–2.34 Å) and five Cl? anions (Pb2+-Cl? = 3.35–3.57 Å). The Cd2+ cation has a symmetric coordination with the formation of two bonds Cd-O = 2.15 Å and four bonds Cd-Cl = 2.73 Å. The oxygen atom is tetrahedrally coordinated by three Pb2+ cations and one Cd2+ cation, which leads to the formation of oxo-centered heterometallic OPb3Cd tetrahedra. The tetrahedra are linked together into chains through common Pb atoms and into layered complexes due to sharing of the equatorial Cd atoms. The chlorine atoms are located above the cavities of the oxo-centered layer. 相似文献
14.
Layered ceramics based on bismuth–calcium cobaltite with varied cobalt oxide contents is synthesized by the solid-phase method, the ceramics phase composition is determined, and the microstructure, thermal expansion, electroconductivity, and thermal electromotive force are investigated. The formation of just one compound, ternary oxide composed of Bi2Ca2Co1.7O y , is established within the quasi-binary Bi2Ca2O5–CoO z system. The effect of the cobalt oxide content on the Bi2Ca2Co x O y ceramics’ microstructure and physicochemical properties is analyzed. The single-phased ceramic sample Bi2Ca2Co1.7O y demonstrated the highest power factor value among all the investigated samples—26.0 μW/(m K2) at a temperature of 300 K. This sample showed the lowest value of the thermal linear expansion coefficient of 9.72 × 10–6 K–1. 相似文献
15.
《Fuel》2005,84(14-15):1968-1974
Removal of Hg0 vapor from the simulated coal combustion flue gases with a commercial activated carbon was investigated using H2S. This method is based on the reaction of H2S and Hg over the adsorbents. The Hg0 removal experiments were carried out in a conventional flow type packed bed reactor system in the temperature range of 80–150 °C using simulated flue gases having the composition of Hg0 (4.9 ppb), H2S (0–20 ppm), SO2 (0–487 ppm), CO2 (10%), H2O (0–15%), O2 (0–5%), N2 (balance gas). The following results were obtained: in the presence of both H2S and SO2, Hg removal was favored at lower temperatures (80–100 °C). At 150 °C, presence of O2 was indispensable for Hg0 removal from H2S–SO2 flue gas system. It is suggested that the partial oxidation of H2S with O2 to elemental sulfur (H2S+1/2O2=Sad+H2O) and the Clause reaction (SO2+2H2S=3Sad+2H2O) may contribute to the Hg0 removal over activated carbon by the following reaction: Sad+Hg=HgS. The formation of elemental sulfur on the activated carbon was confirmed by a visual observation. 相似文献
16.
The crystal structure of a low-temperature modification of the Li12Zn4(P2O7)5 compound has been determined by full-profile analysis from the X-ray powder diffraction data. The compound crystallizes in the monoclinic crystal system (a = 5.130(1) Å, b = 13.454(1) Å, c = 8.205(1) Å, β = 90.36(1)°, space group P21/n, Z = 4) and has a framework structure in which the zinc and lithium atoms statistically occupy equivalent positions. 相似文献
17.
The geometric and topological analysis of the crystal structure of intermetallic Li26Na58Ba38 (cF488, a = 27.335 Å, V = 20 424 Å3, F-43m) is carried out using computer methods (ToposPro software package). The analysis method is based on determining the chemical composition and structure of an intermetallic cluster precursor and constructing a basic 3D network of the structure in the form of a graph whose nodes correspond to the position of their centers of gravity. Using the method of the complete decomposition of the 3D factor graph of the crystal structure into cluster substructures, we find two types of framework-forming nanoclusters, namely, K69 of the 1@16@52 composition and K26 of the 0@4@22 composition with point symmetry g =–43m. The symmetric and topological code of self-assembly of 3D structures from nanocluster precursors is reconstructed in the following form: primary chain → microlayer → microframework. Clusters Ba5, Na6(Na4), and Na2В are determined as spacers occupying voids in the 3D framework of nanoclusters K69 and K26. 相似文献
18.
In the present work, nano SiO2 has been irradiated by a 2 × 1013 n ?cm?2s?1 neutron flux at different times up to 20 h. It has been comparatively analyzed for the frequency dependencies of dielectric loss of the nanomaterial at the initial state and after neutron irradiation. From the analysis results, it is seen that under the influence of neutron flux the dielectric loss of nano SiO2 decreases with increase of neutron flux. Simultaneously, at all temperatures within f(tgδ) = f(f) dependencies there are peaks of more or less extent. The obtained peaks and the mechanism of other effects are identified. 相似文献
19.
Hakbeum Lee Won-Il Kim Kwang-Deog Jung Hyoung Lim Koh 《Korean Journal of Chemical Engineering》2017,34(5):1337-1345
We investigated the effects of different Cu weight ratio on θ or γ-Al2O3 which were impregnated with platinum in terms of catalytic activity for propane dehydrogenation and physicochemical properties. 1.5 wt% Pt, 0-10 wt% Cu catalyst supported on θ-Al2O3 or γ-Al2O3 was prepared by incipient wetness co-impregnation. Enhanced Pt dispersion by increasing Cu contents in γ-Al2O3 supported catalyst was confirmed via XRD and XPS. Pt and CuO was separated in Pt-Cu/θ-Al2O3, but Pt-Cu alloy was identified after reduction treatment. Also, adding Cu in Pt/Al2O3 makes catalyst’s acidity lower and this property led to increased propylene yield in propane dehydrogenation. However, Pt3Cu was not good for yield of PDH, which was confirmed in Pt-10Cu/θ-Al2O3 through XRD. 相似文献
20.
Jingtao Zhi Xianqun Yu Jingjing Bao Xiaoxiang Jiang Hongmin Yang 《Korean Journal of Chemical Engineering》2016,33(6):1823-1830
Titanium dioxide (TiO2) and Mn-doped TiO2 (Mn(x)-TiO2) were synthesized in a sol-gel method and characterized by BET surface area analysis, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Gasphase elemental mercury (Hg0) oxidation and capture by the Mn-doped TiO2 catalyst was studied in the simulated flue gas in a fixed-bed reactor. The investigation of the influence of Mn loading, flue gas components (SO2, NO, O2, and H2O) showed that the Hg0 capture capability of Mn(x)-TiO2 was much higher than that of pure TiO2. The addition of Mn inhibits the grain growth of TiO2 and improves the porous structure parameters of Mn(x)-TiO2. Excellent Hg0 oxidation performance was observed with the catalyst with 10% of Mn loading ratio and 97% of Hg0 oxidation was achieved under the test condition (120 °C, N2/6%O2). The presence of O2 and NO had positive effect on the Hg0 removal efficiency, while mercury capture capacity was reduced in the presence of SO2 and H2O. XPS spectra results reveal that the mercury is mainly present in its oxidized form (HgO) in the spent catalyst and Mn4+ doped on the surface of TiO2 is partially converted into Mn3+ which indicates Mn and the lattice oxygen are involved in Hg0 oxidation reactions. 相似文献