What is chelating agent?
Chelating agents are a class of chemicals that have the ability to chelate metal ions.
The chelating agent, like a crab’s “chela” , clamps down on the metal ion, and the chelating agent and the metal ion form a chelate. The chelate is generally in the shape of a chelating ligand, which is more stable.
Chelating agents are also known as complexing agents, seqestering agents, chelants, chelators.
Functions and uses of chelating agents:
A chelating agent is a chemical named for its function.
First, chelating agents can reduce the adverse effects of metal ions by capturing and controlling the metal ions, and forming stable, water-soluble complexation products.
Three examples are as follows:
- By complexing hard water ions such as calcium and magnesium to form water-soluble products to achieve descaling or scale inhibition directly, or reduce the adverse effect of these ions on the surfactant, which is the main component of the cleaning agent.
For example, water scale remover, softener, scale inhibitor, industrial cleaning agent, daily detergent, oilfield and mineral mining chemicals, etc. - Complexing iron and copper ions to reduce the coloration of iron/copper and other chromogenic color-emitting metal ions.
For example, to improve the whiteness of textile and paper products, and to keep the liquid products clear and bright, e.g. textile chemicals, pulp and paper making chemicals, detergent additives. - Reduce the catalytic oxidative deterioration of iron and copper ions.
For example, as peroxide stabilizers such as hydrogen peroxide bleach; to prevent product deterioration due to ion-catalyzed deterioration, to extend shelf life and reduce the risk of deterioration in the process of use.
Secondly, chelating agent can be used as metal carrier to improve the favorable effect of metal ions.
For example, chelated trace elements in agriculture, iron fortified food, iron ion carrier in gas desulfurization.
Under different temperatures, pH values, and formulation systems, the chelating capacity for different metal ions varies greatly.
List of Green Chelating Agents
| Abbreviation | Product Name | CAS No. | Appearance |
| GLDA-Na | Tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate | 51981-21-6 | Liquid; Solid |
| MGDA-Na | Alanine, N,N-bis(carboxymethyl)-, trisodium salt | 164462-16-2; 170492-24-7 | Liquid; Solid |
| EDDS-Na | L-Aspartic acid, N,N’-1,2-ethanediylbis-, trisodium salt | 178949-82-1 | Liquid |
| Sodium Glucoheptonate 99% | D-glycero-D-gulo-Heptonic acid, sodium salt (1:1) | 13007-85-7; 10094-62-9 | Powder |
| Sodium GlucoHeptoNate 50% | multi-constituent substance (compositions: CAS# 30080-50-3 & CAS# 13007-85-7) | 31138-65-5 | Liquid |
| ASDA-Na | Tetrasodium N,N-bis(carboxylatomethyl)-L-aspartate | 34612-80-1 | Liquid |
| IDS-Na | Aspartic acid, N-(1,2-dicarboxyethyl)-, tetrasodium salt | 144538-83-0 | Liquid; Powder |
| PASP-Na | Aspartic acid, homopolymer, sodium salt | 94525-01-6; 181828-06-8 | Liquid; Powder |
List of Traditional Chelating Agents
| Abbreviation | Product Name | CAS No. | Appearance | Category |
|---|---|---|---|---|
| EDTA | Ethylene diamine tetraacetic acid | 60-00-4 | White crystal solid | Aminopolycarboxylates |
| EDTA Salts | 2Na; 4Na; 2K; 3K | — | Solid; Liquid | Aminopolycarboxylates |
| Chelated fertilizer | Fe; Ca; Zn; Cu; Mg; Mn; EDDHA-Fe; DTPA-Fe | — | Solid; Liquid | Agriculture Nutrients |
| DTPA | DiethyleneTriaminePentaacetic acid | 67-43-6 | White crystal solid | Aminopolycarboxylates |
| DTPA-5Na | Diethylene triaminepentaacetic acid pentasodium salt | 140-01-2 | Liquid | Aminopolycarboxylates |
| DTPA-5K | DTPA penta potassium | 7216-95-7 | Liquid | Aminopolycarboxylates |
| HEDP | Etidronic acid | 2809-21-4 | Liquid; Solid | Polyphosphates |
| PBTCA | 1,2,4-Butanetricarboxylic acid, 2-phosphono- | 37971-36-1 | Liquid | Polyphosphates |
| DTPMP | Diethylene Triamine Penta (Methylene Phosphonic Acid) | 15827-60-8 | Liquid | Polyphosphates |
| ATMP | AminoTri(Methylene Phosphonic acid) | 6419-19-8 | Liquid; Solid | Polyphosphates |
