Influence of Oxygen Concentration and Alkalinity on the Hydrogen Gas Generation by Corrosion of Carbon Steel

2000 ◽  
Vol 663 ◽  
Author(s):  
A. Fujiwara ◽  
I. Yasutomi ◽  
K. Fukudome ◽  
T. Tateishi ◽  
K. Fujiwara
Keyword(s):  
Carbon Steel ◽  
Oxygen Concentration ◽  
Test System ◽  
Hydrogen Gas ◽  
Localized Corrosion ◽  
Generation Rate ◽  
Passive State ◽  
Corrosion Mechanism ◽  
Gas Generation ◽  
Gas Generation Rate

ABSTRACTA repository for low and intermediate level radioactive wastes will contain a great deal of carbon steel as reinforcement materials and waste containers. These steel components are expected to generate hydrogen gas due to reductive corrosion of carbon steel under repository condition. In this study, we have investigated the influence of the environmental factors such as oxygen concentration and pH in the solution on the rate of the gas generation. This rate was measured with a gas flow type test system under the controlled oxygen concentration, which simulates the redox conditions from initial to final environment in a repository. In addition, the corrosion mechanism was examined through the electrochemical tests.As a result, it has been found that pH in the solution and the oxygen concentration considerably affected the generation rate of hydrogen gas in various way. As to the influence of pH of the solution, it has been found that the gas generation rate increased with the increase of pH between 11.8 and 14. Further, as to the influence of the oxygen concentration, when the oxygen concentration in the blowing nitrogen gas was 2 ppm or more, the gas generation rate increased with the oxygen concentration. This trend was possibly caused by local decrease of pH due to localized corrosion. The gas generation rate was very low when the oxygen concentration was in the passive region. The rate was equal to 0.01 μm/y or less if the corrosion occurs with an equation: 3Fe+4H2O → Fe3O4 + 4H2 ↑ to 0.01 *m imcro;/y (hereafter we call this the equivalent corrosion rate). However the gas generation rate increased when the oxygen concentration was controlled to the extent that sufficient passive film cannot be produced and thus it shifts from passive state to active state.

Gas Generation Behavior of Transuranic Waste Under Disposal Conditions

1999 ◽  
Vol 556 ◽  
Author(s):  
Ryutaro Fujisawa ◽  
Tetsunari Kurashige ◽  
Yusuke Inagaki ◽  
Muneaki Senoo
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Initial Period ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Gas Generation ◽  
Geological Disposal ◽  
Synthetic Groundwater ◽  
Gas Generation Rate ◽  
Transuranic Waste

AbstractThe generation of hydrogen-gas from metallic waste is an important issue for the safety analysis of geological disposal facilities for transuranic (TRU) radioactive waste in Japan. The objective of this study is to clarify the gas-generation behavior of stainless steel and carbon steel in non-oxidizing alkaline synthetic groundwater (pH 12.8 and 10.5) at 30 °C simulating geological disposal environments. At pH 12.8, the observed gas-generation rate from stainless steel in the initial period of immersion was 1.0 × 102 Nml/m2/y and 1.0 × 10 Nml/m2/y after 200 days (N represents the standard state of gas at 0 °C and 1 atm). At pH 10.5, gas generation was not observed for 60 days in the initial period. At 60 days, the gasgeneration observed was 5.0 × 10 Nml/m2/y. After 250 days, the gas-generation rate approaches zero. At pH 12.8, the observed gas generation rate of carbon steel in the initial period of immersion was 1.5 × 102 Nml/m2/y and the gas generation rate began to decrease after 200 days. After 300 days, it was 25 Nml/m2/y. At pH 10.5, the gas generation rate in the initial period was 5.0 × 102 Nml/m2/y and was 1.0 × 10 Nml/m2/y after 200 days.

scholarly journals Thickness-dependent photoelectrochemical properties of a semitransparent Co3O4 photocathode

2018 ◽  
Vol 9 ◽  
pp. 2432-2442 ◽  
Author(s):  
Malkeshkumar Patel ◽  
Joondong Kim
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Hydrogen Generation ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Alkaline Electrolyte ◽  
Stoichiometric Ratio ◽  
Gas Generation ◽  
Pec Cells ◽  
Gas Generation Rate

Co3O4 has been widely studied as a catalyst when coupled with a photoactive material during hydrogen production using water splitting. Here, we demonstrate a photoactive spinel Co3O4 electrode grown by the Kirkendall diffusion thermal oxidation of Co nanoparticles. The thickness-dependent structural, physical, optical, and electrical properties of Co3O4 samples are comprehensively studied. Our analysis shows that two bandgaps of 1.5 eV and 2.1 eV coexist with p-type conductivity in porous and semitransparent Co3O4 samples, which exhibit light-induced photocurrent in photoelectrochemical cells (PEC) containing the alkaline electrolyte. The thickness-dependent properties of Co3O4 related to its use as a working electrode in PEC cells are extensively studied and show potential for the application in water oxidation and reduction processes. To demonstrate the stability, an alkaline cell was composed for the water splitting system by using two Co3O4 photoelectrodes. The oxygen gas generation rate was obtained to be 7.17 mL·h−1 cm−1. Meanwhile, hydrogen gas generation rate was almost twice of 14.35 mL·h−1·cm−1 indicating the stoichiometric ratio of 1:2. We propose that a semitransparent Co3O4 photoactive electrode is a prospective candidate for use in PEC cells via heterojunctions for hydrogen generation.

Improved Hydrogen Gas Generation Rate of n-GaN Photoelectrode with SiO[sub 2] Protection Layer on the Ohmic Contacts from the Electrolyte

2010 ◽  
Vol 157 (2) ◽  
pp. B266 ◽  
Author(s):  
Shu-Yen Liu ◽  
J. K. Sheu ◽  
Chun-Kai Tseng ◽  
Jhao-Cheng Ye ◽  
K. H. Chang ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Gas Generation ◽  
Protection Layer ◽  
Gas Generation Rate

Enhanced hydrogen gas generation rate by n-GaN photoelectrode with immersed finger-type indium tin oxide ohmic contacts

2011 ◽  
Author(s):  
Shu-Yen Liu ◽  
Jhao-Cheng Ye ◽  
Yu-Chuan Lin ◽  
Kuo-Hua Chang ◽  
Ming-Lun Lee ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Ohmic Contacts ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Gas Generation ◽  
Gas Generation Rate

Development of Corrosion Inhibitors for Absorption Heat Pumps

2002 ◽  
Author(s):  
C. L. Hannon ◽  
J. Gerstmann ◽  
F. B. Mansfeld ◽  
Z. Sun
Keyword(s):  
Water Absorption ◽  
Corrosion Inhibitors ◽  
Earth Metal ◽  
Heat Pumps ◽  
Generation Rate ◽  
Sodium Chromate ◽  
Gas Generation ◽  
Ammonia Water ◽  
Steel Surfaces ◽  
Gas Generation Rate

This paper describes the results of a research project to develop a non-toxic corrosion in hibitor for the protection of carbon steel surfaces of ammonia-water absorption heat pumps through the use of rare earth metal salt (REMS) compounds. Chromate compounds are currently used as corrosion inhibitors in these systems, but are toxic, environmentally harmful, and their use is being phased out. Corrosion concerns in ammonia-water absorption systems are primarily those of non-condensable (NC) gases generated by corrosion reactions impeding the heat and mass transfer processes in the system. The research focused on the development of a dual-protection REMS based strategy of applying a cerium-oxide/hydroxide coating to the metal surface in a process called cerating, in conjunction with a cerium-sulfate solution-based inhibitor. A laboratory test was conducted in test rigs designed to simulate the conditions of temperature and ammonia concentration found in the desorber component of advanced ammonia-water absorption systems. The test compared the NC gas generation rate in a rig with cerated steel surfaces to a rig using sodium chromate as a solution based inhibitor. The cerated test rig demonstrated an NC gas generation rate about 3 times lower than that of the chromate protected rig. Neither rig showed any indications of significant corrosion activity. This work has shown that cerating can provide superior suppression of NC gas generation in ammonia-water absorption systems compared to sodium chromate, in a process that is simple and readily applicable to the commercial manufacture of equipment.

scholarly journals Corrosion of Carbon Steel in Artificial Geothermal Brine: Influence of Carbon Dioxide at 70 °C and 150 °C

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3801 ◽  
Author(s):  
Gabriela Aristia ◽  
Le Quynh Hoa ◽  
Ralph Bäßler
Keyword(s):  
Carbon Dioxide ◽  
Carbon Steel ◽  
Temperature Effect ◽  
Electrochemical Impedance ◽  
Corrosion Products ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Sem Images ◽  
Geothermal Brine ◽  
Corrosive Effect

This study focuses on the corrosion mechanism of carbon steel exposed to an artificial geothermal brine influenced by carbon dioxide (CO2) gas. The tested brine simulates a geothermal source in Sibayak, Indonesia, containing 1500 mg/L of Cl−, 20 mg/L of SO42−, and 15 mg/L of HCO3− with pH 4. To reveal the temperature effect on the corrosion behavior of carbon steel, exposure and electrochemical tests were carried out at 70 °C and 150 °C. Surface analysis of corroded specimens showed localized corrosion at both temperatures, despite the formation of corrosion products on the surface. After 7 days at 150 °C, SEM images showed the formation of an adherent, dense, and crystalline FeCO3 layer. Whereas at 70 °C, the corrosion products consisted of chukanovite (Fe2(OH)2CO3) and siderite (FeCO3), which are less dense and less protective than that at 150 °C. Control experiments under Ar-environment were used to investigate the corrosive effect of CO2. Free corrosion potential (Ecorr) and electrochemical impedance spectroscopy (EIS) confirm that at both temperatures, the corrosive effect of CO2 was more significant compared to that measured in the Ar-containing solution. In terms of temperature effect, carbon steel remained active at 70 °C, while at 150 °C, it became passive due to the FeCO3 formation. These results suggest that carbon steel is more susceptible to corrosion at the near ground surface of a geothermal well, whereas at a deeper well with a higher temperature, there is a possible risk of scaling (FeCO3 layer). A longer exposure test at 150 °C with a stagnant solution for 28 days, however, showed the unstable FeCO3 layer and therefore a deeper localized corrosion compared to that of seven-day exposed specimens.

Study on the Kinetics and Pyrolysis Behavior of Waste Containing Urea-Formaldehyde Resins

2020 ◽  
Vol 14 (4) ◽  
pp. 444-452
Author(s):  
Ling Fang ◽  
Lin Liu ◽  
Siyi Luo ◽  
Junzhi Wang ◽  
Zongliang Zuo ◽  
...  
Keyword(s):  
Reaction Order ◽  
Urea Formaldehyde ◽  
Coupled System ◽  
Generation Rate ◽  
Formaldehyde Resin ◽  
Gas Generation ◽  
Wood Panel ◽  
Gaseous Products ◽  
Gas Generation Rate ◽  
Theoretical Evidence

In this work, we studied the kinetics and behavior of wood panel wastes containing ureaformaldehyde resins. For this purpose, we used a TG-FTIR coupled system to analyze the gaseous products of the pyrolysis. With the results, we obtained the models that provide theoretical evidence and data support for the studied reactions. According to our findings, the pyrolysis of the ureaformaldehyde components displayed two stages, and the second stage presented a higher intensity. At a temperature of 900 °C, the gas generation rate for hard UF (UF1) was 32.6% higher than that for soft UF (UF2). When temperature increased from 600 °C to 900 °C, the increase of the gas generation rate was relatively small. In addition, the reaction order was obtained using the CoatsRedfern method, which provided a value for the reaction order of 1.4. The activation energy of UF1 was slightly higher than that of UF2. The FTIR analysis indicated that the main gaseous products of the pyrolysis of the urea-formaldehyde resin samples were CO2, H2O, and other compounds containing the C–H and the N–H bond as well as carbonyl groups. In addition, it was determined that Nitrogen was mainly present in the form of hydronitrogen compounds but not as nitrogen oxides. These last may represent a higher degree of pollution.

Generation Mechanism of Hydrogen Gas from Hardened Cement Paste by γ-Irradiation

1994 ◽  
Vol 353 ◽  
Author(s):  
K. Noshita ◽  
T. Nishi ◽  
M. Matsuda
Keyword(s):  
Hydrogen Generation ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Hardened Cement ◽  
Gas Generation ◽  
Γ Irradiation ◽  
Waste Forms ◽  
Two Factors ◽  
G Value ◽  
Hydrogen Radicals

AbstractHydrogen gas is generated from cementitious waste forms by radiolysis of water. In the case of low level radioactive waste, gas yields have been confirmed to be sufficiently low by irradiation experiments. However, studies have suggested that the hydrogen generation rate in cementitious waste forms is larger than the rate calculated from the g-value (H2 yields for 100eV absorbed). In this paper, the factors that increase the gas generation were investigated quantitatively. Two factors were identified, the effect of an organic diethylene glycol which reacts with hydrogen radicals to produce hydrogen, and the effect of electrons generated in the cementitious matrix which decompose water to hydrogen. The hydrogen generation rate was confirmed to drop less than the rate calculated from the g-value when these factors were eliminated.

scholarly journals Factors Influencing Gas Generation Behaviours of Lump Coal Used in COREX Gasifier

2019 ◽  
Vol 38 (2019) ◽  
pp. 30-41
Author(s):  
Runsheng Xu ◽  
Jianliang Zhang ◽  
Wei Wang ◽  
Haibin Zuo ◽  
Zhengliang Xue
Keyword(s):  
Particle Size ◽  
Energy Conservation ◽  
Mass Loss ◽  
Reduction Potential ◽  
Generation Rate ◽  
Coal Rank ◽  
Gas Generation ◽  
Factors Influencing ◽  
Gas Generation Rate ◽  
Lump Coal

AbstractThe influences of coal rank, particle size, temperature and gasifier atmosphere on the gas generation of lump coals used in COREX gasifier were investigated. The results showed that an increase in gasifier temperature and a decrease in particle size hardly affected the final mass loss of lump coals but strongly enhanced the gas generation rate. When the temperature was greater than 1000 °C, a decrease in coal rank increased the gas yield but had little effect on the gas generation rate. Moreover, the promotion ability of the atmosphere for the gas generation rate of lump coal from low to high was as follows: N2, CO2, CO and H2. Considering energy conservation, to improve the gas generation rate of the gasifier, the coal rank and particle size should be decreased first, and afterwards, an increase in reduction potential of the atmosphere in gasifier is also encouraged.

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