Calcium sulfite

Calcium sulfite (CAS 10257-55-3, EC 233-596-8, formula CaSO3) is an inorganic calcium salt also referred to as calcium sulphite or Calciumsulfit. It carries no assigned E-code for direct food use in the EU and is distinct from the more common sodium-based sulfite salts used in preservation.

In water treatment, calcium sulfite acts as a dechlorinating agent by reducing residual chlorine to chloride through a direct redox reaction, protecting downstream membranes and ion-exchange resins. In pulp and paper manufacturing, it functions as a cooking chemical that breaks down lignin under acidic conditions, enabling fiber separation without excessive cellulose degradation.

Calcium sulfite is available in technical and industrial grades as a dry powder, supplied in compliance with REACH registration requirements for EU market access. Procurement quantities are typically offered in 25 kg bags or bulk packaging. Buyers should confirm grade specifications and purity certificates with the supplier prior to ordering.