Which sorbent is commonly used in flue gas desulfurization scrubbers to remove SO2?

Which sorbent is commonly used in flue gas desulfurization scrubbers to remove SO2?

• A. Activated carbon.
• B. Sodium hydroxide.
• C. Lime or limestone.
• D. Water.

Answer: (B)

The key idea is how flue gas desulfurization scrubs remove sulfur dioxide: a basic solid reacts with SO2 as the gas passes through the scrubber, converting it to solid sulfites/sulfates. The most common reagent for this is lime or limestone, which provides calcium compounds that react with SO2 to form calcium sulfite and then calcium sulfate (gypsum) when oxidized. This makes the process effective at neutralizing acidity in the exhaust and yields a useful solid byproduct. Activated carbon isn’t mainly used to remove SO2; it’s used to adsorb certain pollutants like some organics and mercury. Water by itself doesn’t chemically remove SO2 as a sorbent. Sodium hydroxide can absorb SO2, but it’s typically more costly and less common on a large scale than lime/limestone in wet scrubbers.

The key idea is how flue gas desulfurization scrubs remove sulfur dioxide: a basic solid reacts with SO2 as the gas passes through the scrubber, converting it to solid sulfites/sulfates. The most common reagent for this is lime or limestone, which provides calcium compounds that react with SO2 to form calcium sulfite and then calcium sulfate (gypsum) when oxidized. This makes the process effective at neutralizing acidity in the exhaust and yields a useful solid byproduct.

Activated carbon isn’t mainly used to remove SO2; it’s used to adsorb certain pollutants like some organics and mercury. Water by itself doesn’t chemically remove SO2 as a sorbent. Sodium hydroxide can absorb SO2, but it’s typically more costly and less common on a large scale than lime/limestone in wet scrubbers.