Calcium hydroxide reacts with sulfur dioxide to form calcium sulfite. The reaction helps to remove sulfur dioxide from a gas stream by capturing it in the form of a less harmful compound. This process is commonly used in industries to reduce sulfur dioxide emissions.
Basically, sulfur dioxide is a acidic gas. As acid reacts with alkali, carbonates and metals, all 3 are actually ideal to remove sulfur dioxide. However, in the context of removing sulfur dioxide due to air pollution, reacting sulfur dioxide with alkali and carbonate would be more appropriate. For example, removing sulfur dioxide with calcium carbonate would result in calcium sulfate, water and carbon dioxide.
Lime (calcium oxide or calcium hydroxide) is commonly used to remove acidic sulfur dioxide from flue gases. The sulfur dioxide reacts with lime to form calcium sulfite or calcium sulfate, which can then be removed from the gas stream.
Limestone is typically added in the final stages to remove sulfur from coal during a process called flue-gas desulfurization. Limestone reacts with sulfur dioxide to form calcium sulfate, which can then be easily removed.
Sulfur dioxide can be removed by scrubbing the gas with a solution of calcium oxide. The calcium oxide reacts with sulfur dioxide to form calcium sulfite, which can then be further oxidized to calcium sulfate. This process helps to reduce the concentration of sulfur dioxide in the gas stream.
The lime (CaO) reacts with SO2: 2CaO (s) + 2SO2 (g) + O2(g) .........> 2 CaSO4 (s) So the sulphur dioxide is removed and deposited as calcium sulphate.
When sulfur dioxide gas is passed over solid calcium oxide, a chemical reaction occurs to produce solid calcium sulfite. The reaction can be represented by the equation: SO2(g) + CaO(s) -> CaSO3(s). This reaction is used in industries to remove sulfur dioxide from gas emissions.
Automobile exhaust
Sulfur dioxide is produced in a petrol engine when the fuel being burned contains sulfur impurities. As the fuel combusts, sulfur in the fuel reacts with oxygen in the air to form sulfur dioxide, which is then emitted as a pollutant in the exhaust gases of the engine.
When sulfur dioxide reacts with lime water (calcium hydroxide), calcium sulfite is formed. This reaction involves the neutralization of sulfur dioxide, leading to the formation of a white precipitate of calcium sulfite. This reaction is the basis for using lime water as a method to detect the presence of sulfur dioxide gas.
Exhausts can also contain Sulphur Dioxide (SO2) from impurities in the fuel, but only 3% of the total emissions of this substance come from transport, the rest mainly from industry and power generation.
One common solution to remove sulfur dioxide is to use a wet scrubber system. This technology involves spraying a solution (such as a lime or limestone slurry) onto the flue gas containing sulfur dioxide to neutralize and remove it. The sulfur dioxide reacts with the solution to form a solid byproduct that can be easily separated.