Disodium Hydrogen Phosphate (DSP) Supplier

What Is Disodium Hydrogen Phosphate?

Disodium hydrogen phosphate (Na₂HPO₄, DSP, disodium phosphate) is an inorganic sodium salt of phosphoric acid — a dibasic sodium phosphate where two of the three acidic hydrogens of H₃PO₄ have been replaced by sodium. It is available in anhydrous, dihydrate (×2H₂O), and heptahydrate (×7H₂O) forms. In aqueous solution at 1%, DSP produces a mildly alkaline pH of ~9.0–9.5, making it useful as a pH adjustment and buffering agent in mildly alkaline chemical systems. It has good water solubility and is well-established in industrial, food, and pharmaceutical applications.

Boiler Water Treatment

In boiler water treatment, disodium hydrogen phosphate (DSP) is used as part of coordinated phosphate treatment — a programme where controlled phosphate concentrations are maintained in boiler water at specific pH levels to prevent corrosion and scale. DSP reacts with calcium hardness in the boiler to precipitate calcium hydroxyapatite (Ca₅(PO₄)₃OH) as a mobile, non-adherent sludge rather than hard calcium carbonate scale. The phosphate programme is commonly used in medium-pressure boilers, where DSP is dosed in combination with trisodium phosphate (TSP) to achieve the target pH-phosphate relationship. It also reduces corrosion of steel boiler surfaces at the treatment pH.

Food Processing and Other Applications

In food processing, DSP (E339ii) is an approved food additive used as an emulsifying salt in processed cheese (where it emulsifies casein and fat), as a sequestrant, as a humectant, as a yeast nutrient in baking, and as a pH buffer in a range of food products. In detergent formulations, it acts as a builder and pH buffer. In pharmaceutical applications, it is used as a pH buffer in injectable formulations, tablet buffering, and enema preparations. Terracore Chemicals supplies DSP in technical and food grades in 25 kg bags.