ZnEDTA

ZnEDTA is the zinc chelate formed by zinc ions coordinated to ethylenediaminetetraacetic acid (EDTA). In solution the dominant species is the zinc–EDTA complex, [Zn(EDTA)]2-. Commercial formulations are typically salts such as Na2ZnEDTA or K2ZnEDTA, which supply zinc as a highly soluble chelate for practical use.

The EDTA ligand binds zinc through four carboxylate oxygens and two amine nitrogens, creating a stable, octahedral coordination environment. The zinc–EDTA complex is one of the more stable zinc chelates, with formation constants commonly reported in the log K range of about 16 to 17, reflecting strong binding that resists precipitation and loss through simple complexation with competing ligands under typical agricultural and industrial conditions. The complex remains soluble over a broad pH range, though decomplexation can occur under strongly acidic conditions.

Applications of ZnEDTA are mainly agricultural and nutritional. In agriculture, it is used as a zinc micronutrient fertilizer, often in hydroponic systems or soils where zinc availability is limited by pH or other ions. In animal nutrition and feed formulations, ZnEDTA serves as a zinc source with higher solubility and stability than some inorganic zinc salts. It is also used in certain analytical contexts and as a controlled zinc source in some industrial processes.

Environmental and safety considerations include the persistence of EDTA in the environment and its ability to form stable complexes with various metals, which can affect metal mobility in soils and waters. Proper management and regulatory guidelines govern the use of ZnEDTA to minimize unintended environmental effects.