When it comes to hydrogen sulfide gas, many people's first reaction is probably the unpleasant "stinky egg smell". This thing not only has an unpleasant odor, but it is also particularly dangerous at high concentrations, which can cause poisoning and even endanger life. Whether it is generated in industrial production or occasionally appears in daily life, how to safely and effectively eliminate it is a topic worth discussing. Today, let's talk in plain language about the removal methods of hydrogen sulfide gas, from simple tips to professional industrial methods. Let's go through them all.
First, understand the temperament of this' guy 'hydrogen sulfide
Before discussing how to remove it, we need to first understand what hydrogen sulfide is. It is a colorless gas with the chemical formula H ₂ S, and its most prominent feature is the strong odor of rotten eggs, which can be smelled even at low concentrations. But what's interesting is that if the concentration is too high, you won't be able to smell it because it can numb the human olfactory nerve, which makes the danger even greater.
Hydrogen sulfide is not only smelly, but also very toxic. It is a highly toxic gas that can cause damage to the respiratory and nervous systems of the human body when inhaled. In severe cases, it can lead to coma, respiratory failure, and even death. And it is also particularly "active", flammable and explosive, and may explode when exposed to open flames, so it must be handled with care.
There are also many common sources of hydrogen sulfide, such as the production processes of sewage treatment plants, landfills, chemical plants, as well as sewage systems, septic tanks, and even some hot springs that contain hydrogen sulfide gas. The concentration and production of hydrogen sulfide vary in different scenarios, and the removal method also needs to be tailored to local conditions.
Dealing with hydrogen sulfide in daily life
The places where ordinary people are most likely to encounter hydrogen sulfide in their daily lives are the sewers, septic tanks, or when clearing pipelines at home. At this time, the concentration is generally not particularly high, but we cannot take it lightly.
Maintaining ventilation is key
If you smell the smell of rotten eggs, don't think about how to "eliminate" it yet. The first thing to do is to ventilate. Open the doors and windows, let fresh air circulate, dilute the hydrogen sulfide gas and discharge it. If you smell something near the sewer, you can turn on the bathroom exhaust fan or use a fan to blow towards the sewer outlet to accelerate air flow.
Neutralize using simple chemical methods
For hydrogen sulfide in the sewer, some common household items can be used to neutralize it. For example, baking soda, also known as sodium bicarbonate, is a weakly alkaline substance that can react with acidic gases such as hydrogen sulfide to reduce odor and toxicity. You can sprinkle baking soda at the drain and pour some hot water to flush it down the pipe, which can have a certain neutralizing effect.
There is also white vinegar, although it is acidic, the odor it evaporates can mask some of the odor of hydrogen sulfide, and white vinegar itself has a certain bactericidal effect. It can also inhibit the growth of hydrogen sulfide produced by bacterial decomposition in pipelines. However, this method can only provide temporary relief and cannot completely eliminate it.
Do not use open flames, stay away from sources of ignition
As mentioned earlier, hydrogen sulfide is flammable and explosive, so in places with hydrogen sulfide gas, be sure to stay away from open flames and electric sparks. Do not smoke, light candles, or use electrical switches nearby to prevent sparks from causing danger. If you smell something, turn off the nearby electrical appliances first, and then go for ventilation treatment.
Methods for Removing Hydrogen Sulfide in Industrial Production
The concentration and quantity of hydrogen sulfide generated in industrial scenarios are high, requiring more specialized equipment and methods for processing. Most of these methods separate hydrogen sulfide from the gas through chemical reactions or physical adsorption.
Alkali absorption method: using "alkali" to neutralize "acid"
Hydrogen sulfide is an acidic gas, so using alkaline solutions for absorption is one of the most commonly used methods in industry. Just like how we neutralize stomach acid with baking soda, we use strong alkaline solutions such as sodium hydroxide (caustic soda) and potassium hydroxide to react with hydrogen sulfide, producing salts such as sodium sulfide and potassium sulfide. This way, hydrogen sulfide is "fixed" in the solution and will no longer evaporate in gas form.
The principle of this method is simple: H ₂ S+2NaOH=Na ₂ S+2H ₂ O. The sodium sulfide solution generated by the reaction can be further processed, recycled, or discharged after meeting the standards. However, this method requires continuous replenishment of alkaline solution, and the treatment of the generated waste liquid also incurs costs, but its advantage lies in its high efficiency and suitability for treating high concentrations of hydrogen sulfide gas.
Oxidation method: Transforming hydrogen sulfide
Oxidation method is the process of converting sulfide into harmless substances through oxidants, most commonly using oxidants such as chlorine, ozone, and hydrogen peroxide. For example, when treated with chlorine gas, hydrogen sulfide will be oxidized into elemental sulfur or sulfuric acid. The reaction equation is approximately H ₂ S+Cl ₂=2HCl+S ↓, and the generated sulfur is a solid that can precipitate. Hydrochloric acid can be neutralized with alkali to treat it.
Another more environmentally friendly method is biological oxidation, which utilizes the action of certain microorganisms to oxidize hydrogen sulfide into sulfur or sulfate. This method does not require the use of chemical agents, has low cost, and does not generate secondary pollution, making it particularly suitable for places such as sewage treatment plants and landfills that produce hydrogen sulfide. However, microorganisms have relatively high environmental requirements, and temperature and pH values need to be controlled well, otherwise the treatment efficiency will decrease.
Adsorption method: Use a "sponge" to absorb hydrogen sulfide
Adsorption method is like using a sponge to absorb water, using an adsorbent to absorb hydrogen sulfide gas on the surface, thus achieving the purpose of removal. Common adsorbents include activated carbon, molecular sieves, and iron oxide desulfurizers. Activated carbon is well-known to everyone. It has many micropores, a large surface area, and strong adsorption capacity, which can adsorb hydrogen sulfide inside. However, activated carbon will become saturated after a period of adsorption and needs to be regenerated or replaced.
Iron oxide desulfurizer is specifically used to remove hydrogen sulfide. The iron oxide inside it reacts with hydrogen sulfide to produce iron sulfide, thereby "capturing" hydrogen sulfide from the gas. This desulfurizer can be used at room temperature and has high efficiency, making it suitable for treating low concentrations of hydrogen sulfide gas, such as hydrogen sulfide removal in natural gas and coal gas.
Combustion method: Burn hydrogen sulfide into harmless substances
If the concentration of hydrogen sulfide is relatively high and the emissions are stable, combustion method can also be used for treatment. In a specialized combustion device, hydrogen sulfide is fully burned to generate sulfur dioxide and water. The reaction equation is 2H ₂ S+3O ₂ igniting 2SO ₂+2H ₂ O. However, the generated sulfur dioxide is also a pollutant that cannot be directly discharged and requires further treatment, such as absorbing with alkaline solution to produce fertilizers such as ammonium sulfate. This not only treats hydrogen sulfide but also recovers resources.
The combustion method needs to ensure sufficient combustion, otherwise toxic sulfides may be produced, and high temperatures may be generated during the combustion process. Adequate safety measures are required to prevent explosions and fires.
