Hydrogen Sulfide
Hydrogen sulfide (H2S) is a colorless, very poisonous, flammable gas with a foul odor similar to the odor of rotten eggs. In anaerobic digestion, H2S results from the bacterial breakdown of organic matter in the absence of oxygen, as in swamps and sewers. It also occurs in volcanic gases, natural gas, and some well waters.
Hydrogen sulfide is about 20% heavier than air, with a specific gravity of 1.19. Its odors can be recognized in concentrations of <1 mg/kg (air). The odor of hydrogen sulfide will increase as the gas becomes more concentrated. However, in concentrations of ≥150 mg/kg (air), it is not detectable by odor. Due to this property, relying totally on the sense of smell to detect hydrogen sulfide gas can be extremely dangerous because the disappearance of the odor could mean that the gas concentrations have increased.
Hydrogen sulfide is classified as a toxic chemical and in high concentrations will lead to complete respiratory arrest and almost instantaneous poisoning and death. A person overcome by this gas should be removed immediately from the contaminated area and given artificial respiration.
Exposure to lesser concentrations may result in nausea, stomach distress, belching, and coughing. Moderate concentrations may result in eye irritation.
Specifications
| Gas | Hydrogen Sulfide | Gas Density | 1.2 |
|---|---|---|---|
| Chemical Symbol | H2S | Detection Principle | Electrochemical, PID |
| PEL (ppm) | 10 | LEL (%) | 4 |
| IDHL (ppm) | 300 | UEL (%) | 44 |
| Industries | Chemical Processing, Oil & Gas, Water & Waste Water Processing, Pipelines | description | |
| applications |
Products
Industrial Applications
Mining
Also known as “stink damp,” H2S is produced by the decomposition of iron pyrites in coal mines. While flammable and considerably more deadly than carbon monoxide, amounts of this gas are usually only trace. Proper ventilation and monitoring of this and other gases is important in mines.
Production of thioorganic compounds
Several organo-sulfur compounds are produced using hydrogen sulfide. These include methanethiol, ethanethiol, and thioglycolic acid.
Alkali metal sulfides
Upon combining with alkali metal bases, hydrogen sulfide converts to alkali hydrosulfides such as sodium hydrosulfide and sodium sulfide, which are used in the degradation of biopolymers. The depilation of hides and the delignification of pulp by the Kraft process both are effected by alkali sulfides.
A precursor to metal sulfides
Many metal ions react with hydrogen sulfide to give the corresponding metal sulfides. This conversion is widely exploited. For instance, gases or waters contaminated by hydrogen sulfide can be cleaned with metal sulfides. Hydrogen sulfide is used in the purification of metal ores by flotation, to treat mineral powders to enhance the separation, and to passivate metal parts. Catalysts used in hydro-desulphurization are routinely activated with H2S, and the behaviour of metallic catalysts used in other parts of a refinery is also modified using this gas.
Heavy water production for nuclear industry
The Girdler sulfide (GS) process, also known as the Geib-Spevack (GS) process, is an industrial production method for producing “heavy water” (deuterium oxide), an important component in many nuclear reactors because it acts as a neutron moderator.