text: Sodium bisulfite solutions can be prepared by treating a solution of suitable base, such as sodium hydroxide or sodium bicarbonate with sulfur dioxide.
  :SO  +  NaOH  →  NaHSO
  :SO + NaHCO → NaHSO + CO
  Attempts to crystallize the product yield sodium metabisulfite (also called sodium disulfite), NaSO.
  Upon dissolution of the metabisulfite in water, bisulfite is regenerated:
  :NaSO  +  HO   →   2 Na + 2 HSO
  Sodium bisulfite is formed during the Wellman-Lord process.