共查询到20条相似文献,搜索用时 15 毫秒
1.
Adsorption of thallium cations on RuO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript> electrodes
S. Ferro M. Donatoni A. De Battisti V. N. Andreev 《Journal of Applied Electrochemistry》2007,37(11):1389-1394
The electrochemical ion-exchange properties of RuO2–TiO2 film electrodes with different composition have been studied in acidic and alkaline media. Thallium-cation uptake has been
observed only from the latter and its extent was found to be a function of electrode potential and composition. At potentials
near 0.0 V (RHE), the amount of adsorbed Tl+ exhibited a maximum, and decreased with increasing potential, reaching a broad minimum in the range 0.4–0.8 V. A further
increase in the electrode potential, above about 1.0 V, led to an increase of adsorbed thallium species, essentially due to
deposition of a few layers of Tl(III) hydroxide. In fact, the release of the latter species was found to be much slower than
that of thallium ions adsorbed at 0.0 V. For the latter, in turn, the double injection/ejection mechanism, currently accepted
to explain the charge-storage in oxide electrodes, seems to be confirmed. The high Γ values attained at 0.0 V indicate that
the large ionic radius of Tl+ does not prevent its diffusion through the thinner pore texture of the oxide coatings, possibly because of its poor hydration,
related with lower charge density at the ion surfaces. 相似文献
2.
This study investigated the removal of ammonia in wastewater by an electrochemical method using titanium electrodes coated
with ruthenium and iridium (RuO2–IrO2–TiO2/Ti) with low chlorine evolution over-voltage. The effects of operating parameters, including chloride ion concentration,
current density and initial pH, were also investigated. The results were evaluated primarily by considering the efficiency
of the elimination of NH4+-N. The removal of ammonia by electrochemical oxidation mainly resulted from the indirect oxidation effect of chlorine/hypochlorite
produced during electrolysis. The direct anodic oxidation efficiency of ammonia was less than 5%, and the current efficiency
was less than 10%. The ammonia removal followed pseudo-first-order kinetics. The electrochemical process can be applied successfully
as a final polishing step, or as an alternative method to biological nitrification. The process seems to be most beneficial
for small coastal cities 相似文献
3.
4.
A. Rossi V. A. Alves L. A. Da Silva M. A. Oliveira D. O. S. Assis F. A. Santos R. R. S. De Miranda 《Journal of Applied Electrochemistry》2009,39(3):329-337
This work reports on the electrochemical oxidation of oxytetracycline hydrochloride (OTCH) [(4S,4aS,5aS,6S,12aS)-4-dimethylamino-1,4,4a,5, 5a,6,11,12a-octahydro-3,6,10,12,12a-hexahydroxy-6-methyl-1,11-dioxonaphthacene-2-carboxamide] on a RuO2 electrode (DSA®) by cyclic voltammetry and electrolysis. The electrocatalytic efficiency of the electrode material was investigated as a function of different aqueous buffer solutions with pH values of 2.10 and 5.45 as supporting electrolytes. Spectrophotometric studies have shown that OTCH is stable in such solutions. The electrochemical degradation of OTCH is pseudo-first order at both pH values investigated with rate constants, k, of 9.9 × 10?5 s?1 (pH 2.10) and 1.9 × 10?4 s?1 (pH 5.45) at 21 ± 1 °C. Microbiological studies with Staphylococcus aureus ATCC 29213 have shown that OTCH lost antibacterial activity after 120 min of electrolysis at 50 mA cm?2. 相似文献
5.
N. I. Fainer A. N. Golubenko Yu. M. Rumyantsev V. G. Kesler E. A. Maksimovskii F. A. Kuznetsov 《Glass Physics and Chemistry》2011,37(3):322-329
Titanium carbonitride films with a thickness of 80–150 nm have been synthesized by low pressure chemical vapor deposition
from a gas mixture of tetrakis(diethylamino)titanium and ammonia at temperatures of 773–973 K. The film properties have been
studied by spectroscopy (IR, XPS, and EDS), scanning electron and atomic force microscopy, and ellipsometry. The studies have
shown that the films consist of polycrystals with a size of 15–80 nm; their structure contains chemical bonds of titanium
with atoms of carbon, nitrogen, and oxygen. The film composition is consistent with the data of the previously performed thermodynamic
modeling of the deposition of different condensed phases in the Ti-C-N-H-O system. As the deposition temperature increases
in the range under study, the refractive index of the films increases from 2.1 to 2.7. 相似文献
6.
Jong-Soo Bae Joo-Won Park Jae-Ho Kim Jae-Goo Lee Younghun Kim Choon Han 《Korean Journal of Chemical Engineering》2010,27(5):1458-1461
The concept of “waste-to-wealth” is spreading awareness to prevent global warming and recycle the restrictive resources. To contribute towards sustainable development, hydrogen energy is obtained from syngas (CO and H2) generated from waste gasification, followed by CO oxidation and CO2 removal. In H2 generation, it is key to produce more purified H2 from syngas using heterogeneous catalysts. In this respect, we prepared Pt/Al2O3 catalyst with nanoporous structure using precipitation method, and compared its catalytic activity with commercial alumina (Degussa). Based on the results of XRD and TEM, it was found that metal particles did not aggregate on the alumina surface and showed high dispersion. Optimum condition for CO conversion was 1.5 wt% Pt loaded on Al2O3 support, and pure hydrogen was obtained after removal of CO2 gas. 相似文献
7.
Powder precursors have been prepared by means of the sol-gel technique and codeposition, and nanoceramics in the ZrO2-Al2O3-rare-earth (RE) oxide system (RE = Ce, Sc, or Y) based on them have been obtained. Physicochemical properties of the resulting ceramic composites have been investigated. The energy model for oxygen-ionic transport processes in a solid solution based on ZrO2, which relies on computer simulation procedure, has been proposed, and the structural, strength, and electrophysical characteristics of the solid solution have been calculated. The obtained materials are promising as high-melting electrochemical sensors in molten oxides. 相似文献
8.
Abstract
A carbon-nanotube-supported RuO2 nanocatalyst encapsulated in thin silica layer was successfully synthesized. The prior formation of silica over RuO2 nanoparticles effectively hindered catalyst aggregation at high temperatures. The significant improvement of the resistance to sintering and the catalytic selectivity were demonstrated in competitive oxidation of n-butanol and i-butanol and methanol oxidative dehydrogenation. 相似文献9.
10.
Cong Luo Ying Zheng Ning Ding Chuguang Zheng 《Korean Journal of Chemical Engineering》2011,28(4):1042-1046
To improve the stability of CaO adsorption capacity for CO2 capture during multiple carbonation/calcination cycles, modified CaO-based sorbents were synthesized by sol-gel-combustion-synthesis
(SGCS) method and wet physical mixing method, respectively, to overcome the problem of loss-in-capacity of CaO-based sorbents.
The cyclic CaO adsorption capacity of the sorbents as well as the effect of the addition of La2O3 or Ca12Al14O33 was investigated in a fixed-bed reactor. The transient phase change and microstructure were characterized by X-ray diffraction
(XRD) and field emission scanning electron microscopy (FSEM), respectively. The experimental results indicate that La2O3 played an active role in the carbonation/calcination reactions. When the sorbents were made by wet physical mixing method,
CaO/Ca12Al14O33 was much better than CaO/La2O3 in cyclic CO2 capture performance. When the sorbents were made by SGCS method, the synthetic CaO/La2O3 sorbent provided the best performance of a carbonation conversion of up to 93% and an adsorption capacity of up to 0.58 g-CO2/g-sorbent after 11 cycles. 相似文献
11.
12.
M. D. Smolikov V. A. Shkurenok S.S. Yablokova D. I. Kir’yanov A. S. Belyi 《Catalysis in Industry》2018,10(3):222-227
13.
14.
Junyeong Kim Jeong Yeon Do No-Kuk Park Seung Jong Lee Jin-Pyo Hong Misook Kang 《Korean Journal of Chemical Engineering》2018,35(5):1089-1098
Nano-sized bismuth sulfide (Bi2S3) and titanium dioxide (TiO2) with the orthorhombic and anatase tetragonal structures, respectively, were synthesized for application as catalysts for the reduction of carbon dioxide (CO2) to methane (CH4). Four double-layered dense films were fabricated with different coating sequences—TiO2 (bottom layer)/Bi2S3 (top layer), Bi2S3/TiO2, TiO2/Bi2S3: TiO2 (1 : 1) mix, and Bi2S3: TiO2 (1 : 1) mix/Bi2S3: TiO2 (1 : 1) mix—and applied to the photoreduction of CO2 to CH4; the catalytic activity of the fabricated films was compared to that of the pure TiO2/TiO2 and Bi2S3/Bi2S3 doubled-layered films. The TiO2/Bi2S3 double-layered film exhibited superior photocatalytic behavior, and higher CH4 production was obtained with the TiO2/Bi2S3 double-layered film than with the other films. A model of the mechanism underlying the enhanced photoactivity of the TiO2/Bi2S3 double-layered film was proposed, and it was attributed in effective charge separation. 相似文献
15.
Nanoporous silica membrane without any pinholes and cracks was synthesized by organic templating method. The tetrapropylammoniumbromide
(TPABr)-templating silica sols were coated on tubular alumina composite support ( γ-Al2O3/ α-Al2O3 composite) by dip coating and then heat-treated at 550 °C. By using the prepared TPABr templating silica/alumina composite
membrane, adsorption and membrane transport experiments were performed on the CO2/N2, CO2/H2 and CH4/H2 systems. Adsorption and permeation by using single gas and binary mixtures were measured in order to examine the transport
mechanism in the membrane. In the single gas systems, adsorption characteristics on the α-Al2O3 support and nanoporous unsupport (TPABr templating SiO2/ γ-Al2O3 composite layer without α-Al2O3 support) were investigated at 20–40 °C conditions and 0.0–1.0 atm pressure range. The experimental adsorption equilibrium
was well fitted with Langmuir or/and Langmuir-Freundlich isotherm models. The α-Al2O3 support had a little adsorption capacity compared to the unsupport which had relatively larger adsorption capacity for CO2 and CH4. While the adsorption rates in the unsupport showed in the order of H2> CO2> N2> CH4 at low pressure range, the permeate flux in the membrane was in the order of H2≫N2> CH4> CO2. Separation properties of the unsupport could be confirmed by the separation experiments of adsorbable/non-adsorbable mixed
gases, such as CO2/H2 and CH4/H2 systems. Although light and non-adsorbable molecules, such as H2, showed the highest permeation in the single gas permeate experiments, heavier and strongly adsorbable molecules, such as
CO2 and CH4, showed a higher separation factor (CO2/H2=5-7, CH4/H2=4-9). These results might be caused by the surface diffusion or/and blocking effects of adsorbed molecules in the unsupport.
And these results could be explained by surface diffusion.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
16.
N. Papastefanakis D. Mantzavinos A. Katsaounis 《Journal of Applied Electrochemistry》2010,40(4):729-737
The electrochemical oxidation of olive mill wastewater (OMW) over a Ti/RuO2 anode was studied by means of cyclic voltammetry and bulk electrolysis and compared with previous results over a Ti/IrO2 anode. Experiments were conducted at 300–1,220 mg L−1 initial chemical oxygen demand (COD) concentrations, 0.05–1.35 V versus SHE and 1.39–1.48 V versus SHE potential windows,
15–50 mA cm−2 current densities, 0–20 mM NaCl, Na2SO4, or FeCl3 concentrations, 80 °C temperature, and acidic conditions. Partial and total oxidation reactions occur with the overall rate
being near first-order kinetics with respect to COD. Oxidation at 28 Ah L−1 and 50 mA cm−2 leads to quite high color and phenols removal (86 and 84%, respectively), elimination of ecotoxicity, and a satisfactory
COD and total organic carbon reduction (52 and 38%, respectively). Similar performance can be achieved at the same charge
(28 Ah L−1) using lower current densities (15 mA cm−2) but in the presence of various salts. For example, COD removal is less than 7% at 28 Ah L−1 in a salt-free sample, while addition of 20 mM NaCl results in 54% COD reduction. Decolorization of OMW using Ti/RuO2 anode seems to be independent of the presence of salts in contrast with Ti/IrO2 where addition of NaCl has a beneficial effect on decolorization. 相似文献
17.
A new compound of (Rb,K)2Cu3(P2O7)2 is obtained by high-temperature reactions from a mixture of RbNO3, KNO3, Cu(NO3)2, and (NH4)4P2O7. The crystal structure was solved by direct methods and refined to R 1 = 0.056 for 5022 independent reflections. The compound belongs to a rhombic crystal system, P212121, Z = 8, a = 9.9410(7) Å, b = 13.4754(6) Å, c = 18.6353 (3) Å, and R = 0.056. The basis of the structure is a complex copper-phosphate skeleton of the composition of [Cu3(P2O7)2]2–, which can be regarded as consisting of two types of heteropolyhedral layers parallel to the (001) plane. The layers are alternated with each other, forming a frame, in the cavities of which the positions of alkali cations are located, statistically populated with K+ and Rb+ ions. Based on the refined populations of the positions of alkali cations, an exact chemical formula of the compound can be written as Rb1.28K0.72Cu3(P2O7)2. The compound is the most complex among those known to this day of the composition of A2 IB3 II(P2O7)2 (A = Li, Na, K, Rb, or Cs; B = Ni, Cu, or Zn). 相似文献
18.
Yu. K. Startsev A. A. Pronkin I. A. Sokolov I. V. Murin 《Glass Physics and Chemistry》2011,37(3):263-282
The glasses, in which oxygen was partially replaced with sulfur, have been synthesized in the Na2O-P2O5-Na2S system. The chemical and chromatographic analyses of the glasses synthesized have been performed. The temperature-concentration
dependences of electrical conductivity of the glasses have been studied over a wide temperature range; the glass transition
temperatures and the nature of charge carriers have been determined. The IR spectra and Raman spectra have been recorded at
room temperature; the density and microhardness of the glasses and ultrasound velocity have been measured. A comparison of
the electrical conductivities of the investigated glasses with those of the earlier studied glasses in the Na2O-P2O5 system has shown their fair coincidence. The introduction of sodium sulfide into the Na2O-P2O5 system is accompanied by an approximately threefold increase in electrical conductivity, although the concentrations of charge
carriers (sodium ions) in the glasses amount to ∼17 and ∼26 mmol/cm3, respectively. The rise in electrical conductivity has been assumed to be caused by the increase in the degree of dissociation
of polar structural chemical units including sulfide ions and by the higher mobility of sodium ions in the oxygen-free matrix. 相似文献
19.
O. V. Belyaeva T. A. Krasnova S. A. Semenova O. S. Gladkova 《Solid Fuel Chemistry》2011,45(6):418-421
The results of the modification of AG-OV-1 activated carbon under various conditions (by atmospheric oxygen at elevated temperatures
and by hydrogen peroxide or ozone) are given. The effect of the used modifier on changes in the porosity, surface state, and
adsorption capacity of activated carbon is evaluated. 相似文献
20.
CO impedes the low temperature (<170 °C) oxidation of C3H6 on supported Pt. Supported Au catalysts are very effective in the removal of CO by oxidation, although it has little propene oxidation activity under these conditions. Addition of Au/TiO2 to Pt/Al2O3 either as a physical mixture or as a pre-catalyst removes the CO and lowers the light-off temperature (T
50) for C3H6 oxidation compared with Pt catalyst alone by ~54 °C in a feed of 1% CO, 400 ppm C3H6, 14% O2, 2% H2O. 相似文献