The action of tetrasodium hydroxyethylidene diphosphonate
Hydroxyethylidene diphosphonic acid tetrasodium salt (HEDP·Na₄) is the tetrasodium salt of hydroxyethylidene diphosphonic acid, combining strong chelating properties with high water solubility. It has a wide pH applicability range (particularly stable in alkaline systems) and its core function is based on its highly efficient chelating ability toward metal ions such as calcium, magnesium, and iron.
In water treatment applications, it serves as an excellent scale inhibitor and corrosion inhibitor, preventing the deposition of calcium carbonate, calcium sulfate, and other scale deposits in circulating cooling water and boiler systems. It also forms a protective film on metal surfaces, inhibiting corrosion of equipment made of carbon steel, copper, and other materials, thereby extending system lifespan. It is suitable for industrial circulating water systems in power generation, chemicals, and other industries, as well as oilfield injection water systems.
In the detergent and personal care industry, it can chelate metal ions in hard water, enhance cleaning efficacy, prevent detergent components from becoming ineffective due to metal ion interference, and stabilize bleaching agents (such as hydrogen peroxide) to avoid uneven fabric dyeing. Additionally, in textile dyeing, metal processing, and other fields, it is commonly used for water softening and scale removal assistance, serving as an industrial additive that balances functionality and environmental compatibility.
