China
Africa
Explore chapters and articles related to this topic
Atmosphere
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Noble gases are characterized by their lack of chemical reactivity. Noble gases such as Ar and He were present in the Earth’s early atmosphere and continue to be there. Both originated as products of crustal radioactive decay and have increased in concentration over time. However, because of its heavier atomic mass, Ar tends to be retained in the atmosphere, whereas He (because of its low mass) tends to be slowly lost to space.
Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Helium is used in weather balloons and airships. Neon is used in lighting and beacons. Argon is used in electric light bulbs. Krypton and xenon are used in special light bulbs for miners and in light houses (and it doesn’t hurt Superman). Radon is radioactive and is used in tracing gas leaks and treating some forms of cancer. It is also a gas found in homes that can cause harm to the occupants at certain concentrations. Noble gases have a complete outer shell of electrons, two in helium and eight in the rest. It is because of the complete outer shell of electrons that the noble gases are not reactive and do not bond chemically. Elementally, noble gases do have physical hazards. All of them can cause asphyxiation and are usually stored and shipped as cryogenic liquids (Figure 3.23). All of the other elements on the periodic table try to reach the same stable electron configuration.
Radon in Water Supply Wells: Treatment Facility Requirements and Costs
Published in Barbara Graves, Radon, Radium, and Other Radioactivity in Ground Water, 2020
David J. Hiltebrand, John E. Dyksen, Kalyan Raman
Radon-222 is an inert, noble gas that is formed by the radioactive decay of the element radium-226 (1). Radon can enter the drinking water supply from radioactive mining operations, industrial discharge or the decay of naturally occurring radium within the local bedrock. Most often, radon occurs naturally in ground water as a result of the decay of radium in water and in the rock and soil matrix surrounding the water (2). The concentration of radon in water supplies ranges from the background levels of less than 50 picocuries per year (pCi/L) which is normally found in the surface supplies, to over 1,000,000 pCi/L in drilled wells (3).
Seasonal variation of indoor radon–thoron levels in dwellings of four districts of Haryana, India
Published in Science and Technology for the Built Environment, 2019
Amanjeet Panghal, Ajay Kumar, Suneel Kumar
There is an important point about possible correlation between emissions of radon, thoron, and certain types of malignant diseases, due to which the interest in the study of indoor radon and thoron concentrations inside the home has increased (Khan and Azam 2014). Monitoring of radon, thoron, and their decay products in dwellings is an important issue in worldwide. Therefore, it is necessary to measure the radionuclides concentration in subsoil, water, and air to assess the dose for inhabitants to investigate the radiological effect and for base data to estimate variation in background radiation due to human activities in the future. Radon (222Rn) is a radioactive colorless, odorless, and noble gas and is the decay product of radium (226Ra) and one of the elements of the uranium (238U) decay series. The rate of radon emanation depends on many factors, such as temperature, building materials, meteorology, ventilation, and lifestyle of the inhabitants (Rafique et al. 2012), as well as activity concentration of natural radionuclides in building materials (Mayya et al. 1998). Outdoor radon is of lesser concern because it is quickly diluted.
Biodiesel production from sunflower oil using a combined atmospheric cold plasma jet-hydrodynamic reactor
Published in Biofuels, 2023
Marziyeh Ansari Samani, Bahram Hosseinzadeh Samani, Mahdi Ghasemi-Varnamkhasti, Sajad Rostami, Rahim Ebrahimi
Noble gases such as helium or argon are typically used for plasma generation due to the lower voltage required to promote breakdown and sustain the discharge. This research investigated argon gas for plasma production, and the desired jet was designed according to the intensity of argon ionization energy. The reason for using argon gas was its nature as a noble gas that can lead to non-polar reaction mechanisms (with the non-polar reaction mechanism, more alkyl radicals are expected to be produced) [15]. Argon gas also has a relatively low breakdown voltage and is an inert noble gas, so it does not react with reagents or test equipment capable of causing corrosion.
Pathways in the molecular fragmentation for the C2H5OH/He electrical discharge
Published in Radiation Effects and Defects in Solids, 2019
A. Gómez, P. G. Reyes, H. Martínez, J. Vergara, C. Torres, V. Contreras
The electron densities at the order of 1012 cm−3 have been found in previous experimental studies (26,27). ne and Te were evaluated using (3) and (4); the errors of these values are given by standard deviation. In these cases, the errors are 10% for both values. ne and Te as a function of Helium percentage are plotted in Figures 3 and 4. The values for Te are in the range of 1.2 eV to 2.5 eV. The increasing electron temperature for increasing Helium percentage is explained by the decreasing electron energy loses in the inelastic collisions with C2H5OH molecule. By contrast, the values for ne are between 1.2 × 1010 and 105.1 × 1010 cm−3. It shows a decrease of ne as a function of Helium percentage (Figure 3). The value of the electronic density can give information about the chemical reactivity that can generate the plasma. This reactivity is considered as the ability of the system to carry out reactions, bimolecular type or 2 bodies (dissociation, recombination, ionization, excitation, among others); then, the higher the electron density the greater the chemical reactivity of the plasma. Noble gases, such as helium, have layers filled with valence electrons and are extremely stable, so they do not tend to form chemical bonds with other atoms or molecules; in addition, they have little tendency to gain or lose electrons, consequently having a very low level of chemical reactivity. It is for this reason that the increase in the percentage of helium in the mixture decreases the value of the electron density, due to the reduction of the frequency of collisions and reactions with electrons in the system and consequently a reduction in the chemical reactivity. Also, he ratio between ionization cross sections of Helium and C2H6O molecule (σHe/σC2H5OH ≈ 4 × 10−17 cm2/1.6 × 10−16 cm ≈ 0.25 (24,28)) explains the decreasing electron density for decreasing C2H5OH -to He- ratio. For the 100% He case, the Te is consistent with the value obtained by Godyak et al. (25), whereas the value of Flores et al. (29) is 30% higher than the present data. For the 100% C2H5OH case, the value reported by Reyes et al. (30) agrees well with the present data. In the ne case, at 100% He, the values reported by Godyak et al. (25) and Flores et al. (29) are in good agreement with the present data. For 100% C2H5OH, the value obtained by Reyes et al. (30) agrees well with the present data within the experimental error.