Actinium (Ac) in Water Treatment
Quick Answer
Actinium (Ac) is an actinide with atomic number 89. PubChem lists its standard state as solid and its relative atomic mass as 227.02775.
Actinium is relevant mainly to nuclear, mining or radiological waste streams. Treatment requires isotope-specific radiochemical analysis and specialist precipitation, adsorption, ion-exchange or membrane systems with controlled radioactive residuals.
Interesting Facts
- Actinium’s name comes from the Greek aktis, meaning “ray”—an apt name for an intensely radioactive element.
- All actinium isotopes are radioactive; the longest-lived, actinium-227, has a half-life of about 21.8 years.
- This is not a normal drinking-water analyte: any suspected occurrence belongs in an isotope-specific radiochemical investigation.
Water-treatment Design Implications
An element name alone is not enough to select treatment equipment. Confirm chemical form or speciation, total and dissolved concentration, pH, alkalinity, competing ions and the product-water target. Send the water-analysis results to Watermart to identify additional testing and shortlist processes before equipment is specified.
Summary Data Sources
Actinium (Ac)
1. Basic Information
| Atomic Number | 89 |
| Symbol | Ac |
| Atomic Weight | 227 g/mol |
| Electron Configuration | [Rn]6d1 7s2 |
| Discovered by | André Debierne in 1899 |
2. Physical and Chemical Properties
Actinium is a lustrous silver-colored radioactive metal. Some important properties of actinium include:
- Melting point: 1050°C
- Boiling point: 3250°C
- Density: 10.07 g/cm3 at 20°C
- Glows in the dark with a blue light due to its intense radioactivity
- Highly reactive and rapidly oxidized when exposed to air
- Chemical behavior is similar to the rare earth element lanthanum
- Can form compounds with +3 valence
Actinium has about 150 times stronger radioactivity than radium, making it extremely dangerous if not handled properly.
3. Presence in Water and Health Effects
Actinium is very rarely found in nature. In water, its presence is usually associated with uranium or thorium deposits. The isotope actinium-227 is the most commonly found, with a half-life of 21,773 years.
The health effects of exposure to actinium are very serious due to its high radioactivity:
- Even in small amounts, actinium-227 is extremely dangerous if ingested
- Can cause cumulative genetic damage over generations
- Increases the risk of cancer, immune system damage, leukemia, miscarriage, and birth defects
- Long-term exposure even at low doses can be carcinogenic
- In extreme cases, may cause infertility
4. Water Treatment Applications and Removal Methods
Although actinium is rarely found in drinking water, its removal is essential if detected. Some methods that can be used include:
- Ion exchange: Although actinium itself is not very ionically active, specialized ion exchange resins can be used to remove its decay products
- Reverse osmosis: Effective for removing radioactive particles including actinium
- Distillation: Can separate actinium and other radioactive isotopes from water
- Coagulation and filtration: Can remove actinium particles bound to sediment
- Adsorption with activated carbon: Effective for removing some forms of dissolved actinium
Handling of waste generated from these processes requires special safety protocols due to their radioactive nature.
5. Industrial Use in Water Treatment
Actinium has no direct application in industrial water treatment due to its scarcity and hazards. However, research on its behavior in water systems is important for understanding the migration of radionuclides in the environment.
8. Environmental Impacts and Sustainability Considerations
The presence of actinium in the environment has long-term implications:
- May contaminate the food chain, concentrated through bioaccumulation
- Potentially damaging to aquatic ecosystems if present in significant concentrations
- Management of waste containing actinium requires long-term storage and close monitoring
- Remediation of actinium-contaminated sites is very expensive and technically challenging