WASTE MANAGEMENT | CAESIUM REMOVAL
Caesium removal from waste water
Treating acidic wastewater containing radioactive 137 Cs presents challenges
in adsorption due to potential structural damage to adsorbents in acidic conditions and strong competition from protons. A novel layered calcium thiostannate (KCaSnS) that contains Ca2+ as a dopant opens a new way of designing high-performance adsorbents for caesium removal
By Chenyang Yang and Kuk Cho, Department of Environmental Engineering, Pusan National University, Republic of South Korea and Yong Jae Suh, the Korea Institute of Geoscience and Mineral Resources
THE GROWTH OF THE NUCLEAR sector generates environmental and safety problems due to the accumulation of radiotoxic waste. Caesium (Cs) 137 is one of the major fission products and is considered a hazardous radioactive element with a half-life of approximately 30 years. 137
Cs emits beta particles and strong gamma-rays in
the decay process. It is also easily assimilated into the living body because of its high solubility in water and its similar transport behaviour to potassium (K+ selective removal of Cs+
). It is known that from practical nuclear wastewater
is difficult owing to interference with high concentrations of coexisting non-radioactive cations. In particular, a high concentration of protons in acidic wastewater inhibits the removal of Cs+
reprocessing spent fuel and decommissioning nuclear power plants (NPPs) are usually acidic (pH < 2.3) and
effective and selective Cs+ removal from acidic radioactive fluids remains a significant difficulty.
Adsorption solution Adsorption by ion exchange is a promising wastewater remediation technology for NPPs because of its advantage of treating trace amounts of pollutant with ease. Metal sulphides are considered a remarkable selective class of ion exchangers for Lewis-soft acid treatment because of the presence of Lewis-soft base S2- in their structure. However, most of the existing metal sulphides, such as InSnOS, KMS-1, KMPS-1, KMS-2, and KATS-2 showed low adsorption capacity or distribution coefficient for Cs+
in highly acidic . The radioactive wastewaters generated from
conditions. This is because they have only interlayer cations as ion-exchangeable species. A recent report demonstrated that a structural dopant cation, in addition to interlayer
Above: A novel layered calcium thiostannate opens a new way of designing high-performance adsorbents for caesium removal
30 | July 2023 |
www.neimagazine.com
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