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1.
S. A. Umoren 《Cellulose (London, England)》2008,15(5):751-761
The corrosion behaviour of mild steel and aluminium exposed to H2SO4 solution and their inhibition in H2SO4 containing 0.1–0.5 g/L Gum Arabic (GA) used as inhibitor was studied at temperature range of 30–60 °C using weight loss and
thermometric techniques. Corrosion rate increased both in the absence and presence of inhibitor with increase in temperature.
Corrosion rate was also found to decrease in the presence of inhibitor compared to the free acid solution. Inhibition efficiency
increases with increase in concentration of the inhibitor reaching a maximum of 37.88% at 60 °C for mild steel and 79.69%
at 30 °C for aluminium at 0.5 g/L concentration of GA. The inhibitor, GA was found to obey Temkin and El-Awady et al. thermodynamic
kinetic adsorption isotherm for mild steel and aluminium respectively from the fit of the experimental data at all concentrations
and temperatures studied. The phenomenon of chemical adsorption is proposed for mild steel corrosion, while physical adsorption
mechanism is proposed for aluminium corrosion. Results obtained for the kinetic/thermodynamic studies indicate that the adsorption
of GA onto the metals surface was spontaneous. GA is a better corrosion inhibitor for aluminium than for mild steel. 相似文献
2.
Non-isothermal kinetic analysis and feasibilty study of medium grade crude oil field 总被引:1,自引:0,他引:1
M. V. Kök 《Journal of Thermal Analysis and Calorimetry》2008,91(3):745-748
In this research, non-isothermal kinetics and feasibility study of medium grade crude oil is studied in the presence of a
limestone matrix. Experiments were performed at a heating rate of 10°C min−1, whereas the air flow rate was kept constant at 50 mL min−1 in the temperature range of 20 to 600°C (DSC) and 20 to 900°C (TG). In combustion with air, three distinct reaction regions
were identified in all crude oil/limestone mixtures, known as low temperature oxidation (LTO), fuel deposition (FD) and high
temperature oxidation (HTO). The activation energy values were in the order of 5–9 kJ mol−1 in LTO region and 189–229 kJ mol−1 in HTO region. It was concluded that the medium grade crude oil field was not feasible for a self-sustained combustion process. 相似文献
3.
T. Kaljuvee M. Toom A. Trikkel R. Kuusik 《Journal of Thermal Analysis and Calorimetry》2007,88(1):51-58
The extensive use of fossil fuels in energy production causes serious
pollution of atmosphere with SO2, CO2,
NOx, etc. In Estonia the electricity production is
based mainly on the pulverized firing (PF) of low-grade local fuel –
Estonian oil shale (EOS) which is characterized by a low calorific value (~9
MJ kg–1) and a high content of mineral matter
(65–70%) from which approximately 50% are carbonates. Since 2004, also
two boilers based on circulating fluidized bed combustion (CFBC) of EOS are
in exploitation.
The present study is focused on the comparative
investigation of the efficiency of different ashes collected from different
technological points of CFB and PF boilers as sorbents for SO2.
The influence of experimental temperature on the SO2-binding
characteristics of ashes as well as the possibilities of activation of ashes
(grinding, hydration) were investigated. It was shown that the SO2-binding
capacity of initial ashes at 700°C and p(SO2)=190
mm Hg was for CFBC ashes 24–30 mg and for PF ashes 10–23 mg SO2
per 100 mg sample, the best binding capacities belonging to economizer ash
(ECOA) and electrostatic precipitator ash from the 1st field (PESPA1f), respectively.
However, during initial stage of binding the best results were obtained with
air pre-heater ash (PHAA) and ESPA1f (both CFBC ashes). Grinding improved
the SO2-binding ability, being the most effective in
the case of bottom ash (BA) from CFBC and cyclone ash (PCA) from PF –
increase in binding capacity 2 and 2.3 times, respectively. As compared to
initial CFBC ashes, the binding characteristics of PF ashes remained lower
even after grinding. Hydration and previous calcination improved the binding
characteristics only of PF ashes. Hereby, the SO2-binding
ability of CFBC ashes is better than of PF ashes and they are more promising
sorbents for acidic gases, for example, for sulphur dioxide. 相似文献
4.
Andres Trikkel Merli Keelmann Tiit Kaljuvee Rein Kuusik 《Journal of Thermal Analysis and Calorimetry》2010,99(3):763-769
In the present research, CO2 and SO2 binding ability of different oil shale ashes and the effect of pre-treatment (grinding, preceding calcination) of these ashes
on their binding properties and kinetics was studied using thermogravimetric, SEM, X-ray, and energy dispersive X-ray analysis
methods. It was shown that at 700 °C, 0.03–0.28 mmol of CO2 or 0.16–0.47 mmol of SO2 was bound by 100 mg of ash in 30 min. Pre-treatment conditions influenced remarkably binding parameters. Grinding decreased
CO2 binding capacities, but enhanced SO2 binding in the case of fluidized bed ashes. Grinding of pulverized firing ashes increased binding parameters with both gases.
Calcination at higher temperatures decreased binding parameters of both types of ashes with both gases studied. Clarification
of this phenomenon was given. Kinetic analysis of the binding process was carried out, mechanism of the reactions and respective
kinetic constants were determined. It was shown that the binding process with both gases was controlled by diffusion. Activation
energies in the temperature interval of 500–700 °C for CO2 binding with circulating fluidized bed combustion ashes were in the range of 48–82 kJ mol−1, for SO2 binding 43–107 kJ mol−1. The effect of pre-treatment on the kinetic parameters was estimated. 相似文献
5.
The thermal processes during progressive calcination of sulfur-rich calcareous oil shales were analyzed using FT-IR spectroscopy
and applying curve-fitting technique. The spectroscopic analysis is advantageous in the analysis of amorphous and short-range
ordered thermal phases lacking of XRD peaks. The raw calcareous oil shales are composed of organic matter, kaolinite, smectite,
calcite, and apatite (francolite). The principal thermal phases are metakaolinite, meta-smectite, free lime, anhydrite, gehlenite,
and ellestadite. The thermal reactions observed with increase temperatures includes decomposition of organic matter followed
by release of sulfur gas; dehydroxylation of kaolinite; and smectite at 500–600 °C; and thermal transformation to metakaolinite
and meta-smectite; decarbonation of microcrystalline calcite to free lime at 600 °C; reaction of the sulfur gas with the free
lime; formation of anhydrite at 600 °C; reaction of apatite and formation of ellestadite at 800 °C; reaction of the metakaolinite;
the meta-smectite with the free lime; formation of gehlenite at 900 °C. Owingto the sulfatization process, a great part of
the sulfur content of the raw oil shales is retained in the calcined ashes and the release of sulfur gas to the atmosphere
decreases. Thus, the combustion of calcareous oil shales for energy source has less pollution effect than that of the clayey
oil shales. FT-IR spectroscopy and spectral analysis seems to be useful methods for phase analysis of oil shales in combustion
industry. 相似文献
6.
Oil shale ashes from the PAMA demonstration power plant in the Negev region of Israel are produced by fluidized bed combustion
(700–850°C) under short residence time. The FED is organic-rich calcareous raw material rich in carbonate rather than clays.
Thus it is important to ascertain whether the calcite in the ashes is original natural calcite from the raw material or the
product of recarbonation of lime. Three groups of ashes from the power plant, Ash Cooler (AC), Fly Ash (FAS) and Boiler Bank
(BB) were examined using XRD, FT-IR, SEM and isotope analysis methods. The recarbonated calcite is distinguished from the
natural original by smaller crystal size, lower degree of crystallinity and the presence of impurities. High negative δ13C values in oil shale ashes are explained by assuming recarbonation of lime with CO2 originating from the combustion of the organic matter of the raw oil shale. Fly Ash, FAS, and BB, produced from organically-rich
FED, contain more recarbonated calcite than bottom ash, AC. This observation can be explained by the larger grains of the
AC, which do not reach the highest temperature area, and thus most of the original calcite does not decompose.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
The corrosion and corrosion inhibition effect of carboxymethyl cellulose (CMC) for mild steel in sulphuric acid medium was
investigated using chemical (weight loss and hydrogen evolution) techniques at 30–60 °C. The effect of addition of halide
ions (Cl−, Br−, and I−) was also studied. It was found that CMC functions as an inhibitor for acid induced corrosion for mild steel. Inhibition
efficiency increases with increase in immersion time but decreases with increase in temperature. Addition of halide ions reveals
that chloride ions (Cl−) antagonize the inhibition process whereas iodide ions (I−) exert synergistic effect on the corrosion inhibition by CMC. Corrosion inhibitive effect was afforded by adsorption of CMC
molecules onto the mild steel surface both in the absence and presence of halide ions which was found to follow Langmuir adsorption
isotherm model. The phenomenon of physical adsorption is proposed from decrease in inhibition efficiency with increase in
temperature. The inhibition mechanism was further corroborated by the values of thermodynamic and kinetic parameters obtained
from the experimental data. 相似文献
8.
S. Ramanathan M. B. Kakade P. V. Ravindran B. B. Kalekar K. V. Chetty A. K. Tyagi 《Journal of Thermal Analysis and Calorimetry》2006,84(2):511-519
Precursor powders for
yttrium aluminum garnet (YAG) were synthesized by solution combustion reactions
(nitrate–glycine reaction with stoichiometric and sub-stoichiometric
amount of fuel) and simple decomposition of nitrate solution. The TG-DTA,
FTIR and XRD analyses of the precursors and the typical heat-treated samples
were carried out to understand the processes occurring at various stages during
heating to obtain phase pure YAG. Precursors from all the reactions exhibited
dehydration of adsorbed moisture in the temperature range of 30 to 300°C.
The precursor from nitrate–glycine reaction with stoichiometric amount
of fuel (precursor- A) contained entrapped oxides of carbon (CO and CO2)
and a carbonaceous contaminant. It exhibited burning away of the carbonaceous
contaminant and crystallization to pure YAG accompanied by loss of oxides
of carbon in the temperature ranges of 400 to 600 and 880 to 1050°C. The
precursor from simple decomposition of nitrates (precursor-B) exhibited denitration
cum dehydroxylation and crystallization in the temperature ranges of 300 to
600 and 850 to 1050°C. The precursor from nitrate–glycine reaction
with sub-stoichiometric amount of fuel (precursor-C) contained entrapped carbon
dioxide and exhibited its release during crystallization in the temperature
range of 850 to 1050°C. This study established that, in case of metal
nitrate–glycine combustion reactions, crystalline YAG formation occurs
from an amorphous compound with entrapped oxides of carbon. In case of simple
decomposition of metal nitrates, formation of crystalline YAG occurs from
an amorphous oxide intermediate. 相似文献
9.
The effect of thermal annealing of poly(3-octylthiophene) (P3OT) and polystyrene (PS) blend coatings on the corrosion inhibition of stainless steel in a 0.5 M NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride (FeCl3) as oxidant. Stainless steel electrodes with mirror finish were coated with P3OT/PS blend by drop-casting technique. In order to study the temperature effect on the function like physical barrier against the corrosive species of P3OT/PS polymeric blend, the coatings were thermally annealed at three different temperatures (55?°C, 80?°C, and 100?°C). The corrosion behavior of P3OT/PS-coated stainless steel was investigated in 0.5 M NaCl at room temperature, by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy. The LPR values indicated that, at 100?°C, P3OT/PS coatings showed a better protection of the 304 stainless steel in 0.5 M NaCl; the corrosion rate diminished in two orders of magnitude with regard to the bare stainless steel. The superficial morphology of the coatings before and after the corrosive environment was researched by atomic force microscopy, optic microscopy, and scanning electronic microscopy. Morphological study showed that the increased temperature benefited the integration of the two polymeric phases, which improved the barrier properties of the coatings. The coating/metal adhesion and the coating thickness were evaluated. The temperature increases the adhesion degree coating/substrate; thus, the coating annealed at 100?°C showed the best adhesion. 相似文献
10.
The corrosion inhibition of mild steel in hydrochloric acid solution in the presence of three different molecular weights of polyvinyl alcohol (PVA) designated as PVA-I, PVA-II, and PVA-III corresponding to 14,000, 72,000, and 125,000 g mol?1, respectively, was investigated using electrochemical impedance spectroscopy, linear polarization resistance (LPR), and potentiodynamic polarization techniques at 25°C. It was found that PVA of different molecular weights inhibited the corrosion of mild steel in the acid environment. Inhibition efficiency (η%) increases with increase in concentration of the polymers. LPR measurements clearly show that inhibition efficiency increases with increasing molecular weight in the order PVA-III > PVA-II > PVA-I. Polarization curves indicate that PVA functions as a mixed inhibitor affecting both the anodic metal dissolution and cathodic hydrogen evolution partial reactions of the corrosion process. The experimental data obtained fitted well into Langmuir adsorption isotherm model. Physical adsorption mechanism is proposed from the thermodynamic (free energy of adsorption) parameters obtained. 相似文献
11.
Matilda Zemanová 《Chemical Papers》2009,63(5):574-578
Corrosion resistance of zinc coatings was investigated in an accelerated corrosion test in a condensation chamber. Zinc was
electrodeposited from alkaline and acidic electrolytes using direct current (DC) or pulse current (PC). The zinc coating was
subsequently protected against corrosion with a chrome (III) layer. Morphology and structure of the coatings was investigated
using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD)
before and after the corrosion test. Corrosion resistance of alkaline zinc coatings electrodeposited with DC and PC under
test conditions was found to be comparable. The corrosion resistance of zinc coatings deposited from acidic electrolytes by
PC was lower in comparison with corrosion resistance of zinc coatings deposited using DC.
Presented at the 8th Conference on Solid State Chemistry, Bratislava, Slovakia, 6–11 July 2008. 相似文献
12.
X. X. Han X. M. Jiang Z. G. Cui J. W. Yan J. G. Liu 《Journal of Thermal Analysis and Calorimetry》2011,104(2):771-779
For obtaining high shale oil yield as well as treating shale char efficiently and in an environmentally friendly way in a
new comprehensive utilization system of oil shale, a series of fundamental experiments have been conducted for exploring the
effects of retorting factors on shale oil yield and shale char characteristics. Based on these previous studies, in this article,
combustion experiments of shale chars obtained under various retorting conditions were performed with a Q5000IR thermogravimetric
analyzer and a Leitz II-A heatable stage microscope and the effects of retorting factors were discussed on the combustion
characteristics of shale char. Among four studied retorting parameters, retorting temperature and residence time exert very
significant influence on the combustion characteristics of shale char. Either elevating the retorting temperature from 430
to 520 °C or lengthening the residence time at a low retorting temperature will largely decrease residual organic matters
within shale char, resulting in decreasing mass loss in the low-temperature stage of combustion process of shale char, an
elevation of ignition temperature and a shift of ignition mechanism from homogeneous to heterogeneous. One set of retorting
condition was also recommended as a reference for designing the comprehensive utilization system of oil shale studied in this
work: retort temperature of 460–490 °C, residence time of 20–40 min, particle size of <3 mm, and low heating rate of <10 °C/min. 相似文献
13.
The department was commissioned to investigate the possibilities for animal-fat combustion in industrial steam generators
operating originally on fuel–oil or natural gas. There are two main reasons for operating generators on animal fat as a fuel:
On one hand, this material is considered as hazardous waste, thus an important goal is its environmentally benign elimination
or disposal. On the other hand, fat is an excellent energy source and can be used as combustion fuel. This way fossil fuel
usage can be saved while environmental regulations can also be met. The usage of animal fat as a fuel for furnaces required
classification according to fuel classification rules, and comparison with the properties of fuel oil. In addition, its pollutant
content was determined and the effects on the combustion process and emission were investigated. Finally the savings in fossil
fuel energy consumption and related CO2 emission achieved were determined. The first stage involved the determination of the composition of animal fat. Subsequently
other properties such as viscosity and flash point variation were investigated. These data were compared to the properties
of fuel oil. The theoretical investigations of animal-fat classification were promising. Initially one steam generator, originally
designed for fuel oil combustion, was modified and fitted with a parallel animal fat fuel supply system. The results of the
test were encouraging, although there were some problems with power regulation and later with fuel supply. A rotary cup type
burner was then fitted to the boiler. Using this system, all the requirements including environmental regulations were met. 相似文献
14.
Tongyan Pan 《Surface and interface analysis : SIA》2013,45(6):978-984
Corrosion‐induced delamination of an epoxy coating on the AISI/SAE 1045 carbon steel was studied under a humid atmospheric condition (temperature of 25 °C, 1 standard atmospheric pressure, relative humidity of 90%) by the technique of scanning Kelvin probe force microscopy (SKPFM). Surface‐polished 1045 samples were first cold‐coated with the epoxy and then subject to the atmospheric corrosion under the specified condition. At predetermined time intervals, surface Volta potential differences of the samples were measured using the SKPFM over the dry surface of epoxy coating. The map of Volta potential differences demonstrated high contrasts among three characteristic zones: intact steel‐epoxy interface, delaminated interface, and interface with active corrosion, which was then linked to the actual corrosion potential of the steel (measured using a potentiostat with respect to a saturated calomel electrode) based on a rigorous calibration procedure. It was found that the SKPFM was able to provide direct and nondestructive detection of early active corrosion and coating delamination on steels at a submicroscopic resolution, which outperformed the conventional electrochemical techniques for the same purposes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
15.
In this research, pyrolysis and combustion behavior of three different oil shale samples from Turkey were characterized using
thermal analysis techniques (TG/DTG). In pyrolysis experiments, two different mechanisms causing mass loss were observed as
distillation and cracking. In combustion experiments, two distinct exothermic peaks were identified known low and high temperature
oxidation. On the other hand, determination of activation energies are required for the estimation of oil extraction conditions
from the oil shales. Differential methods are used to determine the activation energies of the samples where various f(α) models are applied from the literature. It was observed that the activation energies of the all oil shale samples are
varied between 13.1–215.4 kJ mol−1 in pyrolysis and 13.1–408.4 kJ mol−1 in combustion experiments which are consistent with other kinetic results. 相似文献
16.
Lipiar K. M. O. Goni Prof. Mohammad A. Jafar Mazumder Prof. M. A. Quraishi Dr. Mohammad Mizanur Rahman 《化学:亚洲杂志》2021,16(11):1324-1364
Corrosion is a phenomenon that devastatingly affects innovative, industrial, and mechanical applications, especially in the oil and gas industries. The corrosion conceivably influences industrial equipment; it deteriorates the environment and lessens the equipment/infrastructure's lifetime. Considering the significant impact of corrosion in our daily lives, this review article aims to briefly discuss the significance of corrosion and different control methods with special attention on corrosion inhibitors. The classification of corrosion inhibitors based on types and their advantage/limitations, and heterocyclic compounds as potential corrosion inhibitors, mainly nitrogen-based compounds (pyridine (1N), pyrimidine (2N), and triazines (3N) fused ring benzimidazole, etc.), and their biological significance has been discussed in detail. The mechanism, challenges, and applications of heterocyclic compounds as corrosion inhibitors in various industrial relevant corrosive environments such as acid pickling, descaling operation in the desalination plant, oil gas industry, etc., have also been highlighted in the review. 相似文献
17.
Polypyrrole (PPy) and polypyrrole-tungstate (PPy-WO
4
2−
) coatings were electrodeposited on mild steel (MS) electrodes by cyclic voltammetry (CV) technique. Aqueous oxalic acid solution
was used as supporting electrolyte for these processes. For the electrodeposition of PPy-WO
4
2−
, tungstate anion was added to the supporting electrolyte. The surface morphologies of the two types of coated-samples were
characterized by scanning electron microscopy (SEM) and line-scan EDX analysis. Furthermore, open circuit potential (OCP)
monitoring, polarization and electrochemical impedance spectroscopy methods were performed for comparing the corrosion protection
performances. Corrosion studies indicate that WO
4
2−
dopants can improve corrosion protection properties by taking part in: (i) the passivation process occurred prior to electrodeposition
process, (ii) the electrosynthesis process and incorporation into polymer chain.
The text was submitted by the authors in English. 相似文献
18.
Experimental results on the polarization resistance estimation in a three-electrode setup that consists of two carbon steel
electrodes and the silver reference electrode are presented. The corrosion rate varies with the conditions changing inside
the concrete structure due to its irregular wetting in an aqueous solution of NaCl. The change of polarization resistance
of a single steel electrode can be identified by voltage and current electrochemical noise measurements. The observed change
does not exceed the factor of a few times of the originally recognized value. The newly proposed method of electrochemical
noise analysis for monitoring of swift corrosion rate changes is presented in detail.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 5, pp. 611–616.
The text was submitted by the authors in English. 相似文献
19.
V. P. Yurkinskii E. G. Firsova L. P. Baturova 《Russian Journal of Applied Chemistry》2010,83(10):1816-1821
Corrosion resistance of copper, nickel, and a number of alloys in a NaOH melt in the atmosphere of argon was studied in the
temperature range 400–700°C. 相似文献
20.
V. P. Yurkinskii E. G. Firsova L. P. Baturova 《Russian Journal of Applied Chemistry》2011,84(5):811-814
Corrosion resistance of tantalum, titanium, and a number of carbon materials in a NaOH melt in the atmosphere of argon was
studied in the temperature range 400–700°C. 相似文献