Stability constants (logK values)
– in active pH range
| Stability constants (logK values) – in active pH range | |||||
| Metal ion | EDTA | DTPA | GLDA | MGDA | IDS |
| Al3+ | 16.4 | 18.6 | 12.2 | 7.7 | 14.1 |
| Ba2+ | 7.8 | 8.6 | 3.5 | 4.8 | 3.4 |
| Ca2+ | 10.7 | 10.7 | 6.4 | 7 | 5.2 |
| Cd2+ | 16.5 | 18.9 | 9.1 | 10.6 | 8.4 |
| Co2+ | 16.5 | 18.8 | 10.0 | 11.1 | 10.5 |
| Cu2+ | 18.8 | 21.2 | 13.1 | 13.9 | 13.1 |
| Fe2+ | 14.3 | 16.5 | 8.7 | 8.1 | 8.2 |
| Fe3+ | 25.1 | 28.6 | 11.7 | 16.5 | 15.2 |
| Hg2+ | 21.5 | 26.4 | 14.3 | 14.9 | |
| Mg2+ | 8.7 | 9.3 | 5.5 | 5.8 | 6.1 |
| Mn2+ | 13.9 | 15.2 | 7.6 | 8.4 | 7.7 |
| Ni2+ | 18.4 | 20.1 | 10.9 | 12 | 12.2 |
| Pb2+ | 18 | 18.8 | 10.5 | 12.1 | 11 |
| Sr2+ | 8.7 | 9.8 | 4.1 | 5.2 | 4.1 |
| Zn2+ | 16.5 | 18.2 | 10.0 | 11 | 10.8 |
| Ag1+ | 3.9 | ||||
| Cr3+ | 9.6 | ||||
| different active pH range: different logK in different pH | |||||
| For each metal complex there is an optimum pH and an active pH range in which the metal complex is stable. | |||||
Chelating capacity, as mg metal/g product
logK describes the chelating intensity, the chelating capacity below describes the quantity
| Chelating capacity, as mg metal/g product | ||||||||
| Product | Assay (wt%) | CaCO3 | Ca2+ | Cu2+ | Fe3+ | Mg2+ | Mn2+ | Zn2+ |
| GLDA | 47 | 134 | 53 | 84 | 75 | 33 | 73 | 88 |
| MGDA | 40 | 147 | 59 | 93 | 82 | 36 | 81 | 97 |
| EDTA | 39 | 103 | 41 | 65 | 57 | 25 | 56 | 67 |
| NTA | 40 | 156 | 62 | 99 | 87 | 38 | 85 | 102 |
Different chelating ability in different pH
| different chelating ability in different pH | ||||
| High Acidity | Low acidity | Low alkalinity | High alkalinity | |
| Divalent metals | GLDA, MGDA, EDTA, DTPA | |||
| Hardness (Ca,Mg) | donnot need chelants | GLDA, MGDA | GLDA, MGDA, EDTA, DTPA | |
| Iron control | GLDA, MGDA | GLDA, MGDA, EDTA, DTPA | DTPA | sodium gluconate, Glucoheptonate |
| Applications: Cleaning & detergents, Building & construction, Personal care & Cosmetics,Water treatment chemicals,Pulp and Paper making, Textile auxiliaries,Industrial cleaning, Metal plating & Electronics chemicals, Oilfield chemicals, Photography, etc. | ||||
