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1.
Role of some thiadiazole derivatives as inhibitors for the corrosion of C-steel in 1 M H<Subscript>2</Subscript>SO<Subscript>4</Subscript> 总被引:1,自引:0,他引:1
Inhibition of C-steel corrosion by some thiadiazole derivatives (I–VI) in 1 M H2SO4 was investigated by weight loss, potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance
spectroscopy (EIS) techniques. The presence of these compounds in the solution decreases the double layer capacitance, increases
the charge transfer resistance and increase of linear polarization. Polarization studies were carried out at room temperature,
and showed that all the compounds studied are mixed type inhibitors with a slight predominance of cathodic character. The
effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters
were calculated and discussed. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The
adsorption of the compounds on C-steel was found to obey Langmuir’s adsorption isotherm. The synergistic effect brought about
by combination of the inhibitors and KSCN, KI and KBr was examined and explained. The mechanism of inhibition process was
discussed in the light of the chemical structure and quantum-chemical calculations of the investigated inhibitors. 相似文献
2.
Inhibitive and adsorption properties of ethanol extract of Lasianthera africana for inhibition of corrosion of mild steel in H2SO4 were studied using gravimetric, thermometric, gasometric, and infrared (IR) methods. The extract was found to be a good inhibitor
of corrosion of mild steel in H2SO4. Inhibitive properties of the extract were attributed to enhancement in adsorption of the inhibitor on mild-steel surface
by saponin, alkaloid, tannin, flavanoid, cardiac glycoside, and anthraquinone (present in the extract). Also, adsorption of
the inhibitor was found to be exothermic, spontaneous, and consistent with assumptions of Langmuir and Temkin adsorption isotherms.
Synergistic study revealed that, of the investigated halides, only KCl may enhance adsorption of the inhibitor, whereas KBr
and KI antagonized its adsorption. Based on the decrease in efficiency of the inhibitor with temperature, with values of activation
energy and free energy of adsorption below the threshold values of −40 and 80 kJ mol−1, respectively, a physical adsorption mechanism has been proposed for adsorption of ethanol extract of Lasianthera africana on the surface of mild steel. 相似文献
3.
Mehmet Tunç Mehmet Muhtar Kocakerim Özkan Küçük Mehmet Aluz 《Korean Journal of Chemical Engineering》2007,24(1):55-59
Turkey is the country having the richest boron ores in the world, and colemanite, tincal and ulexite are the ores being mined
mostly in Turkey. These ores are used in the production of various boron compounds of which the production methods are generally
patented. Colemanite ore also is reacted with sulfuric acid to product boric acid. Produced by this method, boric acid contains
various impurities which reduce the market value and are difficult to remove. This study investigated the reaction between
colemanite and ammonium sulfate as an alternative method to produce boric acid. Particle size, ammonium sulfate concentration,
solid to liquid ratio and reaction temperature were chosen as parameters. In results, the conversion rate was increased by
decreasing particle size and solid to liquid ratio, by increasing ammonium sulfate concentration and temperature. A semi-empirical
model with 40.46 kJmol−1 activation energy representing this process was found as follows: 1−(1−X)1/3=2.12×102·C1.38·R−0.75·(S/L)−0.44·e−4866/T·t0.61. 相似文献
4.
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
5.
Zhou-wen Fang Di Wen Zhi-hao Wang Xiang-li Long 《Korean Journal of Chemical Engineering》2018,35(11):2172-2184
The production of isophthalic acid (IPA) from the oxidation of m-xylene (MX) by air is catalyzed by H3PW12O40 (HPW) loaded on carbon and cobalt. We used H2O2 solution to oxidize the carbon to improve the catalytic activity of HPW@C catalyst. Experiments reveal that the best carbon sample is obtained by calcining the carbon at 700 °C for 4 h after being impregnated in the 3.75% H2O2 solution at 40 °C for 7 h. The surface characterization displays that the H2O2 modification leads to an increase in the acidic groups and a reduction in the basic groups on the carbon surface. The catalytic capability of the HPW@C catalyst depends on its surface chemical characteristics and physical property. The acidic groups play a more important part than the physical property. The MX conversion after 180 min reaction acquired by the HPW@C catalysts prepared from the activated carbon modified in the best condition is 3.81% over that obtained by the HPW@C catalysts prepared from the original carbon. The IPA produced by the former is 46.2% over that produced by the latter. 相似文献
6.
A. L. Lapidus A. Yu. Krylova Ya. V. Mikhailova L. V. Sineva A. B. Erofeev 《Solid Fuel Chemistry》2011,45(2):71-80
The effect of the nature of the support of a Co catalyst on the synthesis of hydrocarbons from CO, H2, and C2H4 was studied in this work. It was found that the introduction of ethylene into synthesis gas resulted in an increase in the yield of liquid hydrocarbons. In this case, the conversion of C2H4 was complete and the degree of its involvement into the synthesis of C5+ hydrocarbons depended on the concentration of this component in the starting mixture and the nature of the support. Specific features of the adsorption of CO and C2H4 on the used Co catalysts were determined using a temperature-programmed desorption method. 相似文献
7.
The temperature-concentration dependence of the electrical conductivity of glasses in the Na2SO4-NaPO3 and Na2O-P2O5 systems has been investigated. Based on the obtained experimental data (IR spectra, density, microhardness, sound velocity,
and paper chromatography), it has been demonstrated that SO42− ions form terminal groups through the incorporation into polyphosphate fragments of the structure of glasses in the Na2SO4-NaPO3 system. An increase in the electrical conductivity of glasses in this system by a factor of ∼1000 (as compared to NaPO3) at 25°C and a decrease in the activation energy for electrical conduction from 1.40 to 1.10 eV have been interpreted from
the viewpoint of the decrease in the dissociation energy E
d of polar sulfate phosphate structural chemical fragments formed in the glass bulk upon introduction into sodium metaphosphate
Na2SO4. This leads to an increase in the number of dissociated sodium ions, which are charge carriers, and to a decrease in the
energy (E
a) of their activation shift in the sublattice formed by sulfate phosphate fragments of the structure. 相似文献
8.
In this study, degradation aspects and kinetics of organics in a decontamination process were considered in the degradation
experiments of advanced oxidation processes (AOP),i.e., UV, UV/H2O, and UV/H2O,/TiO2 systems. In the oxalic acid degradation with different H2O2 concentrations, it was found that oxalic acid was degraded with the first order reaction and the highest degradation rate
was observed at 0.1 M of hydrogen peroxide. Degradation rate of oxalic acid was much higher than that of citric acid, irrespective
of degradation methods, assuming that degradation aspects are related to chemical structures. Of methods, the TiO2 mediated photocatalysis showed the highest rate constant for oxalic acid and citric acid degradation. It was clearly showed
that advanced oxidation processes were effective means to degrade recalcitrant organic compounds existing in a decontamination
process. 相似文献
9.
Ho-Sung Yoon Kyung Woo Chung Chul-Joo Kim Jin-Ho Kim Hyung-Seop Lee Seok-Jong Kim Se-Il Lee Seung-Joon Yoo Byung-Chul Lim 《Korean Journal of Chemical Engineering》2018,35(2):470-478
Ferric hydroxide adsorbent was prepared by a chemical treatment process with H2O2, NaOH, and aeration from a Fe2(SO4)3 aqueous solution as a side product discharged from the hydrometallurgical process used to extract neodymium. The ferric hydroxide was used as an adsorbent to prevent eutrophication in water. At the time of synthesis, the most important process variable is the pH condition, which, in this experiment, was changed from pH 3 to 13. The cost of synthesizing ferric hydroxide was sharply reduced by using ferric sulfate, which is considered a side product of the aforementioned hydrometallurgical process, as a starting material, and an adsorbent with high adsorption ability was prepared by controlling the pH level. Microstructural characterization of the synthesized ferric hydroxide revealed particles with a specific surface area of 194.2 m2/g and an average pore diameter of 2.66 nm at pH 6 and 298 K. A column-type packed-bed adsorption experiment was conducted under the following conditions: a flow rate of 0.567 BV/min (3.2 mL/min), 298 K, and atmospheric pressure. The results of the adsorption performance test indicated that the adsorption efficiency of phosphate at concentrations of 10 ppm was 100% at a flow rate of 0.567 BV/min within a contact time of 2 min, and the maximum adsorption capacity for phosphate ions was 65 mg/g. 相似文献
10.
Bahman Zarenezhad Mona Mottahedin Ali Haghighi Asl 《Korean Journal of Chemical Engineering》2011,28(3):949-953
Accurate prediction of phase equilibria regarding CH4 replacement in hydrate phase with high pressure CO2 is an important issue in modern reservoir engineering. In this work we investigate the possibility of establishing a thermodynamic framework for predicting the hydrate equilibrium conditions for evaluation of CO2 injection scenarios. Different combinations of equations of state and mixing rules are applied and the most accurate thermodynamic models at different CO2 concentration ranges are proposed. 相似文献
11.
L. G. Gerasimova R. F. Okhrimenko M. V. Maslova 《Theoretical Foundations of Chemical Engineering》2007,41(5):620-622
The hydrolysis of titanium(IV) sulfate during boiling in the presence of silica gel particles is considered. The scenario of solid-phase formation involves the sedimentation of hydrated titanium(IV) onto reactive silica gel particles; and individual phases of silicon(IV) and titanium(IV) hydroxides are formed. The quantitative ratio between the phases of the hydrated composition dictates the properties of its thermolysis products. Composition-property diagrams are plotted to determine the optimum parameters at which the titanium silicate product has high pigment properties. 相似文献
12.
Performance of CeO2-La2O3/ZSM-5 sorbents for sulfur removal was examined at temperature ranging from 500 oC to 700 oC. The sulfur capacity of 5Ce5La/ZSM-5 was much bigger than that of CeO2/ZSM-5. H2 had a negative impact on the sulfidation; however, CO had little influence on sulfur removal. The characterization results showed that CeO2 and La2O3 were well dispersed on ZSM-5 because of the intimate admixing of La2O3 and CeO2, the major sulfidation products were Ce2O2S and La2O2S, the XRD and SEM results revealed that ZSM-5 structure could remain intact during preparation and sulfidation process, the H2-TPR showed that the reducibility of CeO2 can be remarkably enhanced by addition of La. 相似文献
13.
A detailed analysis of potential versus time measurements at galvanostatic charge/discharge conditions (external current change
from −1 to +1 mA cm−2) for two La–Ni alloys in Ar-saturated 0.1 M KOH solution is presented. It is shown that passivation of the electrodes does
not affect the potential jump as a result of current switching over. The value of potential jump allows to calculate the exchange
current density for H2O/H2 system on the tested material. Anodic potential of the hydrogenated electrode (at i
a = const) linearly increases with logarithm of time which allows to evaluate precisely time necessary for oxidation of hydrogen
absorbed during cathodic charging. The method described enables to determine effectiveness of hydrogen absorption by materials
applied for negative electrodes of NiMH batteries. 相似文献
14.
I. E. Gerasimov D. A. Knyazkov A. G. Shmakov A. A. Paletsky V. M. Shvartsberg T. A. Bolshova O. P. Korobeinichev 《Combustion, Explosion, and Shock Waves》2011,47(1):1-11
This paper presents the measurement and simulation data on the thermal and chemical structure of an atmospheric-pressure premixed
H2/O2/N2 flame doped with iron pentacarbonyl Fe(CO)5. Soft ionization molecular beam mass spectrometry was used to measure concentration profiles of the combustion products of
iron pentacarbonyl: Fe, FeO2, FeOH, and Fe(OH)2. A comparison of experimental and simulated concentration profiles showed that they are in satisfactory agreement for FeO2 and Fe(OH)2 and differ significantly for Fe and FeOH. Thus, the previously proposed kinetic model for the oxidation of iron pentacarbonyl
was tested and it was shown that the mechanism needs further elaboration. 相似文献
15.
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
16.
Sina Esfandiarpour Mohammad Reza Ehsani Parisa Nazemi Ashani Mohammad Hossein Enayati 《Korean Journal of Chemical Engineering》2017,34(11):2933-2943
Nano CuO-Fe2O3/TiO2 adsorbents were made with different compositions of metal oxides using precipitation- desorption method. The adsorbents were applied for adsorption of SO2 at high concentrations ranging from 10,000 to 30,000 ppm and temperatures between 523 and 627 K. Adsorption experiments were applied for adsorbents in a laboratory fixed bed adsorption column. The adsorption capacity was measured by calculating the area under the adsorption curve using the integral method. The results showed that temperature is the most affecting factor on the adsorption capacity. The highest adsorption capacity was obtained by using 17, 8 and 75 wt% of CuO, Fe2O3 and nano TiO2, respectively. Characteristics of the best sorbent were determined by using Fe-SEM, XRD and nitrogen adsorption-desorption analyses. 相似文献
17.
Kitirote Wantala Pongtanawat Khemthong Jatuporn Wittayakun Nurak Grisdanurak 《Korean Journal of Chemical Engineering》2011,28(11):2178-2183
0.1 Fe/Ti mole ratio of Fe-TiO2 catalysts were synthesized via solvothermal method and calcined at various temperatures: 300, 400, and 500 °C. The calcined
catalysts were characterized by XRD, N2-adsorption-desorption, UV-DRS, XRF, and Zeta potential and tested for photocatalytic degradation of alachlor under visible
light. The calcined catalysts consisted only of anatase phase. The BET specific surface area decreased with the calcination
temperatures. The doping Fe ion induced a red shift of absorption capacity from UV to the visible region. The Fe-TiO2 calcined at 400 °C showed the highest photocatalytic activity on degradation of alachlor with assistance of 30 mM H2O2 at pH 3 under visible light irradiation. The degradation fitted well with Langmuir-Hinshelwood model that gave adsorption
coefficient and the reaction rate constant of 0.683 L mg−1 and 0.136 mg/L·min, respectively. 相似文献
18.
E. I. Papaioannou S. Souentie F. M. Sapountzi A. Hammad D. Labou S. Brosda C. G. Vayenas 《Journal of Applied Electrochemistry》2010,40(10):1859-1865
The electrochemical promotion of Pt/YSZ and Pt/TiO2/YSZ catalyst-electrodes has been investigated for the model reaction of C2H4 oxidation in an atmospheric pressure single chamber reactor, under oxygen excess between 280 and 375 °C. It has been found
that the presence of a dispersed TiO2 thin layer between the catalyst electrode and the solid electrolyte (YSZ), results in a significant increase of the magnitude
of the electrochemical promotion of catalysis (EPOC) effect. The rate enhancement ratio upon current application and the faradaic
efficiency values, were found to be a factor of 2.5 and 4 respectively, higher than those in absence of TiO2. This significantly enhanced EPOC effect via the addition of TiO2 suggests that the presence of the porous TiO2 layer enhances the transport of promoting O2− species onto the Pt catalyst surface. This enhancement may be partly due to morphological factors, such as increased Pt dispersion
and three-phase-boundary length in presence of the TiO2 porous layer, but appears to be mainly caused by the mixed ionic-electronic conductivity of the TiO2 layer which results to enhanced O2− transport to the Pt surface via a self-driven electrochemical promotion O2− transport mechanism. 相似文献
19.
Kamila Michalska Paweł Kowalik Wiesław Próchniak Tadeusz Borowiecki 《Catalysis Letters》2018,148(3):972-978
20.
Bo Wu Yuanquan Xiong Jinbo Ru Hao Feng 《Korean Journal of Chemical Engineering》2016,33(12):3407-3416
A novel NO removal system is designed, where NO is initially oxidized by ?OH radicals from the decomposition of hydrogen peroxide (H2O2) over hematite and then absorbed by ammonium-based solution. According to the high performance liquid chromatography (HPLC) profile and the isopropanol injection experiments, the ?OH radicals are proved to play a critical role in NO removal. The NO removal efficiency primarily depends on H2O2 concentration, gas hourly space velocity (GHSV), H2O2 feeding rate and reaction temperature, while the flue gas temperature slightly affects the NO removal efficiency. The low H2O2 consumption makes this system a promising technique in NO removal process using wet-method. The evolution of catalyst in reaction is analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Fourier Transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The nitrite ion and nitrate ion in aqueous solution are detected by the continuous phase flow analyzer. Finally, the macrokinetic parameters of the NO oxidation are obtained by using the initial rate method. 相似文献