Sulfuric acid, or vitriol, is a brownish, odorless, oily mineral acid. Although odorless, it has an obvious acidic taste that is said to be incredibly off-putting. It is generally considered stable and composed of sulfur, hydrogen, and oxygen. The molecular formula for sulfuric acid is H2SO4, and it is water-soluble, meaning it will not burn. It is considered extremely corrosive due to its highly acidic nature and in high concentrations, it is dehydrating and oxidizing. Another interesting property that sulfuric acid exhibits its ability to absorb water vapor from the air, which means its hygroscopic. Because of this, it is highly reactive with most chemicals, especially water.
Where is Sulfuric Acid Found?
Sulfuric acid is a compound that is often found in acid rain which forms when atmospheric oxidization of sulfur dioxide occurs in the presence of water. Sulfur dioxide exists in the atmosphere as a byproduct of the burning of sulfur containing fuels, such as coal and oil. Sulfuric acid also forms through the oxidization of sulfide-based minerals, like iron sulfide. The water by-product of this process is highly acidic and is called acid mine drainage. This stream is so acidic, it is capable of dissolving metals that are present in metal ores. The result of this is brightly colored, highly toxic streams of water.
Sulfuric acid is also produced industrially by oxidizing sulfur dioxide and using a number of different methods to collect the by-product – sulfuric acid. Some (not all) methods of production include: Wet Sulfuric Acid Process, Contact Process, Hydrogen Peroxide Method, and Modified Lead Chamber Process.
Sulfuric acid is a widely used and produced compound and there are several methods of production. It is such a cornerstone in the industrial market that production of sulfuric acid typically goes hand-in-hand and with overall the overall industrial strength of a nation.
Referred to as the “chemical that makes chemicals,” sulfuric acid is used in a variety of different manufacturing processes including pharmaceuticals, dyes and pigments, fertilizers, batteries, insecticides, antifreeze, drain cleaners, detergents, inorganic salts, and explosives. It is also commonly used in the processing of petroleum refining and metallurgical processes. At home, you are most likely to encounter concentrated sulfuric acid in drain cleaner; when handling this common household chemical, it is important to always wear gloves and a mask to avoid negative long-term effects.
Why is Sulfuric Acid a Concern?
The biggest risk associated with sulfuric acid is its high level of corrosiveness. These corrosive properties are greatly accentuated by the fact that sulfuric acid is highly exothermic which means it is reactive with water. Because of this, burns from sulfuric acid are generally considered extremely dangerous due to the dehydrating properties of this acid. Capable of dissolving paper, metal, some stones, and skin, sulfuric acid must be handled with extreme care. On top of being so corrosive, it is slippery in nature. Spills on roads have been known to cause accidents and dangerous conditions.
At high concentrations, aerosol sulfuric acid causes severe damage to the open membranes, such as the eyes and nose. It can also cause blistering, tissue damage, and extreme respiratory tract irritation. Exposure can cause headaches, nausea, and vomiting. Extended exposure can cause damage to the teeth, skin, organs, and lungs. If ingested, this acid is especially dangerous, as it causes irreversible burns, organ damage, and even death. Acid mists containing sulfuric acid are considered highly carcinogenic and have been linked to cancers of the throat and lungs.
The most widely used method of abatement for streams containing sulfuric acid is a wet scrubber. A wet scrubber is a type of pollution control equipment that is designed to remove harmful gases and particulates from industrial exhaust streams. It works by funneling the sulfuric acid through the bottom of a packed tower and then it passes through an engineered packing, where a solution from specialized nozzles is sprayed countercurrent to the exhaust stream flow.
Because sulfuric acid is very corrosive, specially designed materials must be used to build the scrubber. Stainless steel alloy is the most commonly used material, however there are other very good options. Fiber reinforced plastic, polypropylene, or Polytetrafluoroethylene (PTFE) fiberglass reinforced plastic (FRP) are commonly used.
When the waste gas has lower solubility, chemicals are usually added to the solution. These chemicals are carefully chosen to react with the sulfuric acid released in the exhaust stream. After the sulfuric acid is treated, the stream is released, clear of the dangerous sulfuric acid and other targeted chemicals and / or particles. Although it is clear of dangerous compounds, the gas released from the scrubber often looks like steam.
With sulfuric acid being one of the most widely used compounds in the industrial world, GCES has extensive experience handling and abating this acid. If you would like to speak with one of our scrubber experts, please email us at firstname.lastname@example.org, or call us at 1.832.476.9024.
Additional articles in the GCES series ‘Abating Hazardous Air Pollutants’ include:
Part 2: Chlorine Abatement
Part 6: SOx, the compounds of sulfur and oxygen molecules including Sulfur Monoxide, Sulfur Dioxide and Sulfur Trioxide
Part 11: Sulfuric Acid – H2SO4
Part 12: Ethylene Oxide – EtO