Sodium metabisulfite is a commonly used dechlorination agent with the chemical formula Na2S2O5. The function of dechlorinating agents is to convert chloride ions in chlorine containing substances into harmless sodium chloride.
The dechlorination principle of sodium metabisulfite is achieved by reacting sulfite ions (S2O3 ^ 2-) with chloride ions (Cl -), the reaction generates sulfate ions (SO4 ^ 2-) and sodium chloride (NaCl). The specific reaction equation is as follows:
2Na2S2O5+4Cl – → 2Na2SO4+4NaCl+SO2 ↑
In the reaction, sodium metabisulfite is oxidized by chloride ions, generating sulfate ions and sodium chloride, accompanied by the release of sulfite gas.
Sulfite ions are a strong reducing agent that can reduce chloride ions in chlorides to chlorides. The sulfite ions themselves are oxidized into sulfate ions.
The selection and use of dechlorinating agents should be determined based on specific circumstances, and different dechlorinating agents may be suitable for different chlorine containing substances. When using sodium metabisulfite as dechlorination, it is necessary to control the reaction conditions to avoid the release of harmful gases and ensure the efficient progress of the dechlorination reaction.