Neutralization of acidic wastewater containing saturated sodium sulfate
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In a saturated sodium sulfate acidic solution, is it possible to add solid NaOH (caustic soda) or soda ash (Na2CO3) to neutralize it? Can solid bases dissolve in a saturated sodium sulfate solution? If they cannot dissolve, they will not be in an ionic state and therefore cannot carry out neutralization. Is that correct?
It’s wastewater; it’s recommended to use lime for neutralization in order to precipitate some of the sulfate ions. The excess quicklime can also be used to recover caustic soda.
It is possible to use sodium hydroxide for neutralization; if sodium sulfate is supersaturated, crystals will form.
If solid waste issues are not taken into account, it is still better to use lime.
Lime is indeed cheap, but after calcium sulfate is produced, Ca2+ is added to the wastewater; if further treatment is required, that becomes a **problem**.