Control Of Sulphur Oxides

Flue Gas Desulfurization (FGD) units remove SO from exhaust gases of coal-based and industrial boilers.
The most widely used method globally is the wet limestone–gypsum process.
Limestone (CaCO ) is preferred because it is low-cost, widely available, and reacts efficiently with SO .
The key chemical reactions occurring inside an FGD absorber are:


The final product gypsum can be sold to the cement and construction industry.
Titanium oxide is used as a catalyst/pigment, not for SO removal.
Fenton reagent is used in wastewater oxidation, not air pollution control.
Beryllium oxide is toxic and not used industrially for flue gas treatment.
Hence, limestone is the correct and universally used raw material in FGD systems.
Final Answer: Limestone