Trace amount of Cobalt-60 is generated in nuclear reactors and needs higher selective separation competing with sister heavy elements, especially Fe-triad. Cobalt has been seen to adsorb on activated carbon and zeolites, but they require a higher pH more than 7. We are concerned about pH range lower than 3.
try other natural absorbent like dolomite and bentonite, if dose not work. i think you need to try a synthetic absorbent .
However, zeolite has good absorption potential, thus may be its activation by base or heat help you to get better result
Mohammad K. Younes Thanks for insightful comment. The main issue is competition with other heavy metals, such as, Cs adsorbed in low pH range.
Selective adsorbents for radioactive cobalt (Co) in lower pH conditions are typically designed to target the specific chemical characteristics of cobalt ions, often Co(II) in solution. Here are some materials that are known to be effective:
1. **Activated Carbon**: Modified forms of activated carbon, especially those impregnated with functional groups or coated with specific materials, can enhance cobalt adsorption.
2. **Zeolites**: Natural and synthetic zeolites are microporous, aluminosilicate minerals that can effectively adsorb cobalt ions. The ion-exchange properties of zeolites make them suitable for this purpose, especially at lower pH levels where other adsorbents might be less effective.
3. **Functionalized Silica Gel**: Silica gels functionalized with specific ligands, such as thiol or amine groups, have shown high selectivity for cobalt ions in acidic conditions.
4. **Titanium Dioxide (TiO2)**: Nano-sized TiO2 particles have been found to adsorb cobalt ions efficiently. The surface properties of TiO2 can be modified to improve its selectivity and capacity for cobalt adsorption.
5. **Bioadsorbents**: Certain biological materials, such as algae, fungi, or bacteria, can bind cobalt ions through various mechanisms including ion exchange, complexation, and chelation. These bioadsorbents can be particularly effective at lower pH levels.
6. **Metal-Organic Frameworks (MOFs)**: MOFs are crystalline materials with high surface areas and tunable pore sizes. Specific MOFs can be designed to have high selectivity for cobalt ions even under acidic conditions.
7. **Chelex 100 Resin**: This is a chelating resin that contains iminodiacetic acid functional groups, which have a high affinity for divalent metal ions like cobalt. It works effectively in a wide range of pH conditions.
8. **Amidoxime-functionalized adsorbents**: Amidoxime groups have a high affinity for metal ions and have been used to create adsorbents that can selectively bind cobalt in acidic environments.
9. **Hydroxyapatite (HAp)**: This calcium phosphate compound can adsorb heavy metals, including cobalt, due to its ion-exchange properties and is effective in acidic conditions.
10. **Chitosan and its derivatives**: Chitosan, a biopolymer derived from chitin, and its chemically modified forms can efficiently adsorb cobalt ions due to the presence of amine and hydroxyl functional groups.
When choosing an adsorbent, it's essential to consider factors such as the specific pH range, the concentration of cobalt, the presence of other competing ions, and the operational conditions of the adsorption process.
Thank you Shekh Mohammad Mostafa for your answer, but it seems like a CHATGPT answer, no specific selectivity.
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