Environmental Impact and Health Effects of Hydrogen
Friday, March 13th, 2009
Dr.Badruddin Khan
Hydrogen, the first element in the periodic table, is a colorless, odorless and insipid gas, formed by its diatomic molecules, in normal conditions. The hydrogen atom is formed by a nucleus with one unit of positive charge and one electron. It’s one of the main compounds of water and of all organic matter, and it’s widely spread not only in the Earth but also in the entire Universe. There are three hydrogen isotopes: protium, mass 1, found in more than 99,985% of the natural element; deuterium, mass 2, found in nature in 0.015% approximately, and tritium, mass 3, which appears in small quantities in nature, but can be artificially produced by various nuclear reactions.
Hydrogen forms 0.15 % of the earth’s crust and it is the major constituent of water. 0.5 ppm of hydrogen H2 and variable proportions as water vapor are present in the atmosphere. Hydrogen is also a major component of biomass, constituting the 14% by weight. Hydrogen occurs naturally in the atmosphere. The gas will be dissipated rapidly in well-ventilated areas. Any Effect of hydrogen on plants or animals would be related to oxygen deficient environments. No adverse effect is anticipated to occur to plant life, except for frost produced in the presence of rapidly expanding gases. No evidence is currently available on the effect of hydrogen on aquatic life.
Hydrogen is the most flammable of all the known substances. It is slightly more soluble in organic solvents than in water. Many metals absorb hydrogen. Hydrogen absorption by steel can result in brittle steel, which leads to faults in the chemical process equipments. At normal temperature hydrogen is a not very reactive substance, unless it has been activated somehow; for instance, by an appropriate catalyser. At high temperatures it’s highly reactive. Although in general it’s diatomic, molecular hydrogen dissociates into free atoms at high temperatures. Atomic hydrogen is a powerful reductive agent, even at ambient temperature. It reacts with the oxides and chlorides of many metals to produce free metals. It reduces some salts to their metallic state and reacts with a number of elements, both metals and non-metals to produce their hydrides. Atomic hydrogen reacts with organic compounds to form a complex mixture of products. The heat released when the hydrogen atoms recombine to form the hydrogen molecules is used to obtain high temperatures in atomic hydrogen welding.
The most important use of hydrogen is the synthesis of ammonia. The use of hydrogen is extending quickly in fuel refinement, like the breaking down by hydrogen (hydrocracking), and in sulphur elimination. Huge quantities of hydrogen are consumed in the catalytic hydrogenation of unsaturated vegetable oils to obtain solid fat. Hydrogenation is used in the manufacture of organic chemical products. Huge quantities of hydrogen are used as rocket fuels, in combination with oxygen or flour, and as a rocket propellant propelled by nuclear energy. Hydrogen can be burned in internal combustion engines. Hydrogen fuel cells are being looked into as a way to provide power and research is being conducted on hydrogen as a possible major future fuel. For instance it can be converted to and from electricity from bio-fuels, from and into natural gas and diesel fuel, theoretically with no emissions of either CO2 or toxic chemicals.
As hydrogen is extremely flammable, its many reactions may cause fire or explosion. As the gas mixes well with air, explosive mixtures are easily formed. Moreover the gas is lighter than air. The gas can be absorbed into the body by inhalation and high concentrations can cause an oxygen-deficient environment. Individuals breathing such an atmosphere may experience symptoms which include headaches, ringing in ears, dizziness, drowsiness, unconsciousness, nausea, vomiting and depression of all the senses. The skin of a victim may have a blue color. Under some circumstances, death may occur. Hydrogen is not expected to cause mutagenicity, embryotoxicity, teratogenicity or reproductive toxicity. Pre-existing respiratory conditions may be aggravated by overexposure to hydrogen. When inhaled a harmful concentration of this gas in the air will be reached very quickly.
Heating may cause violent combustion or explosion as the gas reacts violently with air, oxygen, halogens and strong oxidants causing fire and explosion hazard. Metal catalysts greatly enhance these reactions. High concentrations in the air cause a deficiency of oxygen with the risk of unconsciousness or death. We must check oxygen content before entering a suspected area as there is no odor warning if toxic concentrations are present. We may measure hydrogen concentrations with suitable gas detector (a normal flammable gas detector is not suited for the purpose). In case of inhalation problem we should shut off its supply. In case it not possible and there seems no risk to surroundings, let the fire burn itself out; in other cases extinguish with water spray, powder, carbon dioxide. In case of fire we should keep its cylinder cool by spraying with water. One must combat fire from a sheltered position and rush for medical aid and advice in case of all inhalation and contact cases.
Deuterium
Deuterium is the stable, nonradioactive isotope of hydrogen, commonly called heavy hydrogen because its atomic weight is approximately doubles that of ordinary hydrogen, but it has identical chemical properties. Deuterium has about twice the atomic weight of normal hydrogen because its nucleus contains a proton and a neutron, instead of just a proton. Hydrogen as it occurs in nature contains approximately 0.02 percent of deuterium that was the first isotope to be separated in a pure form from an element. Several methods have been used to separate the isotope from natural hydrogen. The two processes that have been most successful have been fractional distillation of water and a catalytic exchange process between hydrogen and water. In the latter system, when water and hydrogen are brought together in the presence of a suitable catalyst, about three times as much deuterium appears in the water as in hydrogen. Deuterium has also been concentrated by electrolysis, centrifuging, and fractional distillation of liquid hydrogen. The nuclei of deuterium atoms, called deuterons, are much used in research in physics because they can be readily accelerated by cyclotrons and similar machines and used as “atomic bullets” to transform an atom of one element into another element. Deuterium also has important uses in biological research as a tracer element for studying problems of metabolism.
Regular hydrogen and deuterium are not normally metallic, meaning they are not shiny or malleable. Scientists have used pressure and heat, however, to force deuterium to act like a metal, making it shinier and easier to compress. Studying deuterium in compressed and highly hot conditions can help scientists understand how hydrogen behaves in the hot, heavily pressurized interiors of planets and in the interiors of stars. The use of heavy water as a moderator in atomic piles has been suggested and Deuterium, either in deuterium oxide or in lithium deuteride, and tritium are essential components of nuclear fusion weapons, or hydrogen bombs.
Tritium
Tritium is the radioactive hydrogen isotope of atomic mass 3 and symbol 1H3 or T. The nucleus of a tritium atom consists of a proton and two neutrons. It undergoes decay by beta emission to give a helium nucleus of mass 3; it has a half-life of 12.26 years. Tritium is produced in a number of ways, including the bombardment of deuterium compounds with high-energy deuterons and by the absorption of neutrons by the lithium isotope of mass 6. Some tritium is produced in the upper levels of the atmosphere by the bombardment of nitrogen with energetic neutrons produced by cosmic rays; rainwater is usually found to contain minute amounts of tritium. The enormous amount of energy released when tritons react with deuterons in the so-called nuclear-fusion process makes tritium an important constituent of hydrogen bombs. Tritium is also used as a tracer in chemical and biochemical research.
Hydrogen, the first element in the periodic table, is a colorless, odorless and insipid gas, formed by its diatomic molecules, in normal conditions. The hydrogen atom is formed by a nucleus with one unit of positive charge and one electron. It’s one of the main compounds of water and of all organic matter, and it’s widely spread not only in the Earth but also in the entire Universe. There are three hydrogen isotopes: protium, mass 1, found in more than 99,985% of the natural element; deuterium, mass 2, found in nature in 0.015% approximately, and tritium, mass 3, which appears in small quantities in nature, but can be artificially produced by various nuclear reactions.
Hydrogen forms 0.15 % of the earth’s crust and it is the major constituent of water. 0.5 ppm of hydrogen H2 and variable proportions as water vapor are present in the atmosphere. Hydrogen is also a major component of biomass, constituting the 14% by weight. Hydrogen occurs naturally in the atmosphere. The gas will be dissipated rapidly in well-ventilated areas. Any Effect of hydrogen on plants or animals would be related to oxygen deficient environments. No adverse effect is anticipated to occur to plant life, except for frost produced in the presence of rapidly expanding gases. No evidence is currently available on the effect of hydrogen on aquatic life.
Hydrogen is the most flammable of all the known substances. It is slightly more soluble in organic solvents than in water. Many metals absorb hydrogen. Hydrogen absorption by steel can result in brittle steel, which leads to faults in the chemical process equipments. At normal temperature hydrogen is a not very reactive substance, unless it has been activated somehow; for instance, by an appropriate catalyser. At high temperatures it’s highly reactive. Although in general it’s diatomic, molecular hydrogen dissociates into free atoms at high temperatures. Atomic hydrogen is a powerful reductive agent, even at ambient temperature. It reacts with the oxides and chlorides of many metals to produce free metals. It reduces some salts to their metallic state and reacts with a number of elements, both metals and non-metals to produce their hydrides. Atomic hydrogen reacts with organic compounds to form a complex mixture of products. The heat released when the hydrogen atoms recombine to form the hydrogen molecules is used to obtain high temperatures in atomic hydrogen welding.
The most important use of hydrogen is the synthesis of ammonia. The use of hydrogen is extending quickly in fuel refinement, like the breaking down by hydrogen (hydrocracking), and in sulphur elimination. Huge quantities of hydrogen are consumed in the catalytic hydrogenation of unsaturated vegetable oils to obtain solid fat. Hydrogenation is used in the manufacture of organic chemical products. Huge quantities of hydrogen are used as rocket fuels, in combination with oxygen or flour, and as a rocket propellant propelled by nuclear energy. Hydrogen can be burned in internal combustion engines. Hydrogen fuel cells are being looked into as a way to provide power and research is being conducted on hydrogen as a possible major future fuel. For instance it can be converted to and from electricity from bio-fuels, from and into natural gas and diesel fuel, theoretically with no emissions of either CO2 or toxic chemicals.
As hydrogen is extremely flammable, its many reactions may cause fire or explosion. As the gas mixes well with air, explosive mixtures are easily formed. Moreover the gas is lighter than air. The gas can be absorbed into the body by inhalation and high concentrations can cause an oxygen-deficient environment. Individuals breathing such an atmosphere may experience symptoms which include headaches, ringing in ears, dizziness, drowsiness, unconsciousness, nausea, vomiting and depression of all the senses. The skin of a victim may have a blue color. Under some circumstances, death may occur. Hydrogen is not expected to cause mutagenicity, embryotoxicity, teratogenicity or reproductive toxicity. Pre-existing respiratory conditions may be aggravated by overexposure to hydrogen. When inhaled a harmful concentration of this gas in the air will be reached very quickly.
Heating may cause violent combustion or explosion as the gas reacts violently with air, oxygen, halogens and strong oxidants causing fire and explosion hazard. Metal catalysts greatly enhance these reactions. High concentrations in the air cause a deficiency of oxygen with the risk of unconsciousness or death. We must check oxygen content before entering a suspected area as there is no odor warning if toxic concentrations are present. We may measure hydrogen concentrations with suitable gas detector (a normal flammable gas detector is not suited for the purpose). In case of inhalation problem we should shut off its supply. In case it not possible and there seems no risk to surroundings, let the fire burn itself out; in other cases extinguish with water spray, powder, carbon dioxide. In case of fire we should keep its cylinder cool by spraying with water. One must combat fire from a sheltered position and rush for medical aid and advice in case of all inhalation and contact cases.
Deuterium
Deuterium is the stable, nonradioactive isotope of hydrogen, commonly called heavy hydrogen because its atomic weight is approximately doubles that of ordinary hydrogen, but it has identical chemical properties. Deuterium has about twice the atomic weight of normal hydrogen because its nucleus contains a proton and a neutron, instead of just a proton. Hydrogen as it occurs in nature contains approximately 0.02 percent of deuterium that was the first isotope to be separated in a pure form from an element. Several methods have been used to separate the isotope from natural hydrogen. The two processes that have been most successful have been fractional distillation of water and a catalytic exchange process between hydrogen and water. In the latter system, when water and hydrogen are brought together in the presence of a suitable catalyst, about three times as much deuterium appears in the water as in hydrogen. Deuterium has also been concentrated by electrolysis, centrifuging, and fractional distillation of liquid hydrogen. The nuclei of deuterium atoms, called deuterons, are much used in research in physics because they can be readily accelerated by cyclotrons and similar machines and used as “atomic bullets” to transform an atom of one element into another element. Deuterium also has important uses in biological research as a tracer element for studying problems of metabolism.
Regular hydrogen and deuterium are not normally metallic, meaning they are not shiny or malleable. Scientists have used pressure and heat, however, to force deuterium to act like a metal, making it shinier and easier to compress. Studying deuterium in compressed and highly hot conditions can help scientists understand how hydrogen behaves in the hot, heavily pressurized interiors of planets and in the interiors of stars. The use of heavy water as a moderator in atomic piles has been suggested and Deuterium, either in deuterium oxide or in lithium deuteride, and tritium are essential components of nuclear fusion weapons, or hydrogen bombs.
Tritium
Tritium is the radioactive hydrogen isotope of atomic mass 3 and symbol 1H3 or T. The nucleus of a tritium atom consists of a proton and two neutrons. It undergoes decay by beta emission to give a helium nucleus of mass 3; it has a half-life of 12.26 years. Tritium is produced in a number of ways, including the bombardment of deuterium compounds with high-energy deuterons and by the absorption of neutrons by the lithium isotope of mass 6. Some tritium is produced in the upper levels of the atmosphere by the bombardment of nitrogen with energetic neutrons produced by cosmic rays; rainwater is usually found to contain minute amounts of tritium. The enormous amount of energy released when tritons react with deuterons in the so-called nuclear-fusion process makes tritium an important constituent of hydrogen bombs. Tritium is also used as a tracer in chemical and biochemical research.
