Selective cesium removal from radioactive liquid waste by crown ether immobilized new class conjugate adsorbent

• Published in: Journal of hazardous materials 2014-08, Vol.278, p.227-235
• Main Authors: Awual, Md. Rabiul, Yaita, Tsuyoshi, Taguchi, Tomitsugu, Shiwaku, Hideaki, Suzuki, Shinichi, Okamoto, Yoshihiro
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Applied sciences; Cesium; Cesium Radioisotopes - chemistry; Conjugate adsorbent; Conjugates; Crown Ethers - chemistry; Devices; Ethers; Exact sciences and technology; General purification processes; Hydrogen-Ion Concentration; Ligands; Liquid wastes; Nuclear liquid waste; Pollution; Radioactive cesium; Radioactive Pollutants - chemistry; Radioactive Waste; Reuses; Selectivity; Silicon Dioxide - chemistry; Waste Disposal, Fluid - methods; Waste water; Wastewaters; Water treatment and pollution
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2014.06.011

•DB24C8 crown ether was functionalized for preparation of conjugate adsorbent.•Radioactive 137Cs can be selectively removed by the conjugate adsorbent.•Adsorbent can effectively capture Cs even in the presence of a high amount Na & K.•Adsorbent is reversible and able to be reused without significant deterioration. Conjugate materials can provide chemical functionality, enabling an assembly of the ligand complexation ability to metal ions that are important for applications, such as separation and removal devices. In this study, we developed ligand immobilized conjugate adsorbent for selective cesium (Cs) removal from wastewater. The adsorbent was synthesized by direct immobilization of dibenzo-24-crown-8 ether onto inorganic mesoporous silica. The effective parameters such as solution pH, contact time, initial Cs concentration and ionic strength of Na and K ion concentrations were evaluated and optimized systematically. This adsorbent was exhibited the high surface area-to-volume ratios and uniformly shaped pores in case cavities, and its active sites kept open functionality to taking up Cs. The obtained results revealed that adsorbent had higher selectivity toward Cs even in the presence of a high concentration of Na and K and this is probably due to the Cs–π interaction of the benzene ring. The proposed adsorbent was successfully applied for radioactive Cs removal to be used as the potential candidate in Fukushima nuclear wastewater treatment. The adsorbed Cs was eluted with suitable eluent and simultaneously regenerated into the initial form for the next removal operation after rinsing with water. The adsorbent retained functionality despite several cycles during sorption-elution-regeneration operations.