What is hydrogen sulfide?

Hydrogen Sulfide, its chemical formula is H₂S, is an inorganic compound composed of two elements: hydrogen and sulfur. Under normal temperature and pressure, it appears as a highly toxic colorless gas with a unique odor similar to rotten eggs. However, it should be noted that when the concentration of hydrogen sulfide exceeds a certain value (usually ≥100ppm), the olfactory nerve will be paralyzed and unable to detect the smell, which makes high concentrations of hydrogen sulfide gas more dangerous, because people can be exposed to high concentrations of hydrogen sulfide without even noticing it.

What is the concentration standard?

Occupational Exposure limit (OEL)

The Occupational Safety and Health Administration (OSHA) sets the occupational exposure limit for hydrogen sulfide at 10ppm in the case of an 8-hour weighted average.

The permissible short exposure concentration (STEL) is 15ppm and the exposure time cannot exceed 15 minutes.

Concentrations Immediately threatening life and health (IDLH)

When the concentration of hydrogen sulfide reaches 100ppm, it becomes an immediate threat to life and health, and evacuation measures must be taken immediately.

Specific effects at different concentrations

At concentrations between 0.13 and 4.6ppm, people can smell the rotten egg odor of hydrogen sulfide.

Once the concentration reaches 10-20 PPM, protective gear needs to be worn.

When the concentration reaches 50-100ppm, it can irritate people's eyes and respiratory tract.

At levels above 500ppm, confusion can occur, which can lead to death if left untreated.

What are the physical parameters?

Molecular weight : 34.08g /mol

Density (25℃, 1atm) : 1.36 kg/m³ (heavier than air, air density is 1.2 kg/m³)

Melting point : -85.5℃

Boiling point : -60.7℃

The critical temperature : 100.4℃

The critical pressure : 9.01 MPa

Solubility (25 ° C) : Solubility in water is 0.38 g/100mL, can generate weakly acidic hydrosulfuric acid (H₂S, home H⁺ + HS⁻)

What are the requirements for packaging and containers?

High pressure cylinder packaging

Hydrogen sulfide gas is typically packaged in high pressure cylinders of carbon or stainless steel that meet relevant U.S. Department of Transportation (DOT) standards, such as DOT-3AA or equivalent.

The working pressure of the cylinder is generally between 150 and 200 bar, and the specific filling amount will vary according to the specifications and design standards of the cylinder.

Special container requirements

For liquid hydrogen sulfide, thermally insulated cryogenic containers need to be used for storage because liquid hydrogen sulfide has a low boiling point (-60.7 ° C) and a low temperature environment needs to be maintained to prevent its gasification.

Security signs and labels

All containers storing and transporting hydrogen sulfide gas must be clearly marked with warning signs for skulls and crossbones, as well as hazard statements such as "toxic gas" and "flammable" to remind people of its dangers.

what is the main application?

Industry Field

In the process of oil and gas extraction, hydrogen sulfide is a common associated gas. In order to ensure safety, it is necessary to use amine liquid absorption method and other processes to desulfurize it.

Hydrogen sulfide can also be used to produce sulfides such as sodium sulfide (Na₂S) and sodium hydrosulfide (NaHS), which have a wide range of applications in the paper and textile industries.

In the metalworking industry, hydrogen sulfide can be used for etching and cleaning metal surfaces, such as in the manufacturing of electronic components, where it can be used to etch metal surfaces to achieve the desired shape and accuracy.

Laboratory and research purposes

In the laboratory, hydrogen sulfide is often used as a chemical reagent for the detection of metal ions such as Pb²⁺, Cd²⁺, etc., as it can react with these metal ions to form insoluble sulfide precipitates.

Medical and biological research

In recent years, it has been found that low concentration of hydrogen sulfide has physiological effects such as regulating vascular tone and anti-inflammation, so it has received more and more attention in the field of medicine and biological research.

Field of Agriculture

In agriculture, hydrogen sulfide can be used for soil disinfection and pest control, such as in greenhouses, where hydrogen sulfide gas can be used to kill pathogenic bacteria and pests in the soil, thereby improving the yield and quality of crops.

How to store and transport?

Storage requirements

Storage of hydrogen sulfide gas should be selected in a cool, well-ventilated place, away from fire and heat sources, to prevent direct sunlight.

The temperature of the storage place should not exceed 30℃, and it is necessary to avoid mixing with strong oxidants (such as oxygen and chlorine) and acids, because hydrogen sulfide may have violent chemical reactions and even cause explosions in contact with these substances.

Storage sites must be equipped with leak detection and alarm devices and forced ventilation equipment so that leaks can be detected and dealt with in time.

Requirements for transportation

The transportation of hydrogen sulfide gas must comply with the relevant provisions of the Regulations on the Safety Management of Hazardous Chemicals, use special dangerous goods transport vehicles, and be equipped with professional escort personnel.

During transportation, ensure that the cylinder is firmly fixed to prevent collision and leakage. Transport vehicles should avoid passing through densely populated areas and high temperature areas, and should be equipped with necessary emergency treatment equipment and protective equipment.

Transport requires compliance with relevant international regulations, such as the International Maritime Dangerous Goods Code (IMDG Code) and the International Air Transport Association Dangerous Goods Code (IATA DGR).

Safety protection and emergency treatment measures

Personal protective equipment

Positive pressure air breathing apparatus (SCBA) must be worn when entering places where hydrogen sulfide gas may be present to ensure safe breathing.

At the same time, wear protective equipment such as chemical protective clothing, protective gloves and goggles to prevent skin and eyes from coming into direct contact with hydrogen sulfide gas.

Emergency treatment of leakage

Once hydrogen sulfide gas leakage occurs, the emergency plan should be immediately activated, the personnel in the leakage area should be evacuated, and a warning area should be set up to prohibit irrelevant personnel from entering.

Emergency personnel should wear positive pressure air breathing apparatus and use explosion-proof tools to plug the leak to prevent sparks from causing explosions.

Spray water can be used to dilute the leaking hydrogen sulfide gas to reduce its concentration, while paying attention to prevent the diluted solution from causing pollution to the environment.

First aid measures for poisoning

If someone is poisoned by inhaling hydrogen sulfide gas, he/she should be immediately moved to fresh air and his/her respiratory tract should be kept open.

If the victim stops breathing, artificial respiration should be given immediately and sent to the hospital for treatment as soon as possible. On the way to the hospital, cardiopulmonary resuscitation and other first aid measures should be continued.

Summary

Hydrogen sulfide, as a gas with highly toxic and flammable characteristics, is widely used in industrial production and daily life. However, its danger can not be ignored, so in the process of storage, transportation and use, we must strictly abide by the relevant safety norms and operating procedures, take effective protective measures to ensure the safety of personnel and the environment. At the same time, with the deepening of the research on hydrogen sulfide, its potential application value in medicine, biology and other fields will be gradually developed and utilized.