More information about the origin of H2S gas
The Swedish chemist – Carl Wilhelm Scheele is said to be the first to discover the chemical composition of hydrogen sulfide gas in 1777..
Is H2S toxic? Does it affect human health?
As mentioned above, H2S gas is very toxic. A small amount of this gas in the air can cause severe poisoning in humans and animals as well as adverse health effects.
♦ Inhaling even a small amount of H2S can make us poisoned, dizzy and vomiting because it is very toxic
♦ In the worst cases, it can cause general paralysis and death..
Although H2S gas is usually produced by humans, it does not accumulate in our body. It only affects us when the existing concentration is beyond the allowable limit.
The toxicity of hydrogen sulfide is on par with that of HCN and 5 to 6 times higher than that of CO
If employees regularly work in an environment consisting of H2S gas, it is very difficult to recognize this gas.
Their body’s reflexes gradually get used to this rotten egg odor, so people do not realize its existence and the dangerous effects to their health in the future.
♦ VH2S in low content only adversely affects the respiratory system, mucosa and cornea
♦ High concentration of hydrogen sulfide will paralyze olfactory nerve cells and lead to dizziness and sudden death.
♦ H2S can make plants lose their leaves and reduce the ability of plants to grow naturally.
What is the chemical properties of H2S gas?
Weak acidity of hydrogen sulfide gas:
H2S gas is a water-soluble chemical element then produces a very weak hydrochloric acid solution (weaker than H2CO3 acid) with H + + HS- K1 = 6.10-8 and HS- H + + S 2- K2 = 10-14
H2S gas reacts with alkaline solutions to create two types of salt including neutral salt and acid salt:
- H2S + 2NaOH = Na2S + 2H2O
- H2S + NaOH = NaHS + H2O
In particular, when H2S reacts with alkali metal carbonate salt solution, the resulting product is only hydro carbonate salt.
- H2S + Na2CO3 = NaHCO3 + NaHS
H2S gas has strong reducing properties
In H2S acid and its salts, Oxidation number of S is -2 showing the properties of a strong reducing agent. H2S burns in air with a blue flame.
- 2H2S + 3O2 → 2 H2O + 2SO2
If there is not enough air, H2S will be oxidized to S. Chlorine can oxidize H2S gas to H2SO4 (in case of water).
- 4Cl2 + H2S + 4H2O → H2SO4 + 8 HCl
H2S chemically reacts with alkali metals to form acid salts.
They will form sulfide salts when acting with other metals. Anhydrous H2S does not react with Cu, Ag, Hg. But in the presence of water vapor, it acts with these metal quite quickly then makes the surface of the metals gray.
- 4 Ag + 2H2S + O2 → 2Ag2S + 2H2O
How to prepare H2S?
In laboratories, H2S is prepared by the reaction between hydrochloric acid solution and iron (II) sulfide:
FeS + 2HCl → FeCl2 + H2S↑
More information about the origin of H2S gas
H2S gas is colorless, extremely toxic and its characteristic odor is of rotten egg. It exists in the atmosphere and directly affects human health.
The source of H2S is extremely diverse, so it is easily contaminated with H2S emissions in the atmosphere. The treatment of H2S emissions is becoming more and more urgent.
H2S gas can be generated from natural sources, such as: organic matter decomposed under the action of bacteria without oxygen, sewers, landfills, and ponds … This process is also known as anaerobic digestion is performed by sulfate reduction microorganisms.
H2S also exists in the mixture of volcanic gas, natural gas and in water sources of some well, groundwater, …
Human and animal bodies also produce small amounts of H2S and use this gas as a signaling molecule.
It is generated from artificial sources such as petroleum refining, fiber regeneration, metallurgy, food processing..
What is the actual impact and effect of H2S?
The effects caused by H2S gas generated in production facilities or industrial plants are often greater and more serious than that in residential areas. Because the concentration of H2S gas produced from there is much greater.
It is also the reason why equipment, machines and piping systems are corroded quickly.
According to the documents of the US Occupational Safety and Health Administration (OSHA), the concentration of H2S gas below 0.025ppm will be difficult to detect. Because its smell is not clear, it is up to the person to feel it or not. At the concentration from 3 to 5ppm, H2S gas will have a clearer, unpleasant odor, like the smell of rotten eggs.
This gas has heavier odor and causes pleural irritation at the concentration of about 100ppm. If you inhale it for about 1 hour, your eyes and respiratory tract will be irritated. Furthermore, continued inhaling it for more than 8 hours can lead to death.
H2S gas at the concentration of about 400 ppm to 700 ppm can make the victim be in danger. If the concentration is above 800 ppm, the victim is likely to immediately lose consciousness and die.
The National Center for Biotechnology Information (USA) has shown that H2S has a very strong and fast impact in our bodies, almost like cyanide.
According to current statistics in the US, about 24% of H2S poisoning accidents are encountered in the garbage disposal process. And about 18% of them occur in the natural gas industry. In particular, the H2S asphyxiation deaths occurred up to 87% at the scene and there are often two or more deaths in 21% of accidents. In many cases, the dead one is the person coming to the rescue or assisted the victim.
Safety principles when using H2S:
- Before being put into use, H2S cylinders must be tested for safety and registered for use according to current regulations.
- The ones who use the equipment must give management responsibility for H2S gas cylinders by written to equipment managers.
- The operation of H2S cylinders is only authorized for people at least 18 years old. They must be trained and tested to meet the requirements of professional knowledge and get good health.
- To ensure safety when using H2S gas, the gas cylinders need to be checked on whether they are with enough safety equipment before using.
- Please store and place the gas cylinder at least 5 meters away from heat sources and not in explosive places.
- You must regularly measurement tools and check out H2S gas cylinders while operating.
- Operate the H2S gas cylinders according to the safety procedure of the unit.
In addition, it is necessary to know how to recognize the leakageand handle urgently while working. When detecting a strong odor, you must move to a ventilated area as quickly as possible.
the status get worse, you should breathe oxygen. In addition, when working with H2S gas should wear full protective equipment.
The detailed information, properties, applications as well as harm of H2S gas are above. If you need more consultancy, please contact MIGCO at Hotline: 091.837.7766 – Mr.Vinh.