Sodium Hydroxide

In sodium scrubbing, a solution of sodium hydroxide, sodium carbonate or sodium bicarbonate absorbs the SO₂ from the flue gas. The SO₂ reacts to form sodium sulfite and sodium bisulfite which are dissolved in solution. Part of all of the sulfites can be oxidized to form sodium sulfate. Sodium scrubbing differs from lime or limestone-based systems in that no solid waste is produced. Because of the high reactivity of the sodium alkali sorbent compared to the lime or limestone sorbents, these systems are characterized by a low liquid-to-gas ratio.