(185e) Crown Ether Tethered on Silica Supports As Reusable Adsorbents for the Selective Capture of Cesium Ions in Water

The underdeveloped renewable energy technology suggests that reliance to nuclear energy is likely to persist in the near future. Among the perils posed by nuclear energy production is widespread environmental contamination by cesium.¹³⁷Cs is an artificial radioactive gamma emitter substance commonly found as a product of a nuclear fission reaction that occurs in nuclear weapons, or in nuclear reactors, used for the generation of electricity at nuclear power plants. With a half-life of t_1/2 = 30 y, it can persist in the environment with long-term harmful effects. It can be emitted to the atmosphere during nuclear accidents or into the surface/ground water. Due to its high mobility and solubility in water, radiocesium can bioaccumulate in aquatic environment and can be ingested by the public through contaminated seafood and drinking water. Despite these alarming concerns on Cs contamination, there are no established decontamination methods for ¹³⁷Cs, necessitating the development of specialized materials. In this paper, a robust mesoporous silica-based Cs⁺ adsorbent was prepared using crown ethers (CE) for selective Cs⁺ capture. The mesoporous silica (SiO₂) was functionalized with linkers on which the pre-modified CEs were covalently tethered. The CEs and their intermediates were characterized by FTIR, ¹H NMR and ¹³C NMR, while the composite SiO₂ materials were characterized using FTIR, TGA, BET, and SEM-EDX. Batch adsorption experiments in single- and multi-metal ion systems were performed to evaluate the performance of the modified silicieous materials as affected by various factors. Overall results demonstrate the potential of the CE@SiO₂ adsorbents for selective Cs⁺ removal.

This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (No. 2018R1D1A1B07047503 and No. 2017R1A2B2002109, No. 22A20130012051 (BK21Plus)).