[[Alconox]] https://technotes.alconox.com/industry/advanced-cleaning-mechanisms/advanced-cleaning-mechanisms-chelation/ ## Chelators coordinate metal ions with multiple bonds ![[chelators are claws]] ## Types of chelators ### Hard chelants Bind strongly to metal ions with **one chelator binding to one cation** - Na4EDTA (tetra sodium ethylenediaminetetraacetate) - citric acid (or salts thereof) - sodium gluconate - phosphates ### Soft chelants bind more loosely with variable stoichiometry (ratio) - polymeric compounds such as sodium polyacrylate. ## Chelators have two main functions in a detergent ### Chelators maintain detergent performance in hard water - [[Hard water reduces detergent availability]]. ### Chelators increase critical cleaning action of a detergent #### Mechanisms of dissolving [[limescale]] ##### in an acidic environment - carbonate -> carbonic acid -> carbon dioxide. ##### with chelators - A chelator such as EDTA will sequester cations from the limescale and solubilize - **does not require chemical modification** - **can be carried out at neutral or even basic pH** #### residues with high calcium concentration ex: from milk products - central metal ions stabilize the soil and make it adhere to the surface more strongly through potential cross linking - with a chelator sequestering the metal ions, the rest of the soil is more easily removed by surfactants #### stains caused by metal oxides ex: rust stains from leaving fine metal dust on surfaces