Bonding of crown ethers to α-zirconium phosphate-Novel layered adsorbent for radioactive strontium separation

Searching for new efficient, selective, and stable, adsorbents for Sr-90 generated in the nuclear fuel cycle remains important. In the last year, 18 crown 6ether and its derivatives have been intensively studied as highly efficient ion-exchangers for removal of Sr-90. However, one of the main problems for further application of these expensive macrocyclic ligands is loss in solid-liquid media due to their solubility. To overcome this problem, in this work, we have developed a new organic - inorganic layer alpha-ZrP composite by intercalation of 4-amino-benzo-18 crown 6. This new alpha-ZrP composite (AM-ZrP) not only inherits the advantages of 4-amino-benzo-18 crown 6 and alpha-ZrP, exhibiting excellent stability under acid and radioactive conditions, but also efficiently decreases the loss of valuable4-amino-benzo-18 crown 6 in the adsorption process. Furthermore, the preparation process for AM-ZrP is simple and it can be easily produced on a large-scale. Remarkably, having a pore size matching4-amino-benzo-18 crown 6, AM-ZrP shows high selectivity for capturing Sr2+ from complicated mixed solutions. The maximum adsorption capacity for Sr2+ onto AM-ZrP is 320.16 mg.g(-1), which is about five times that of neat alpha-ZrP. Itsurpasses most other inorganic adsorbents, which can be attributed to the much higher number of adsorption sites and the wide interlayer spacing of alpha-ZrP after interactionwith4-amino-benzo-18 crown 6. Our present work not only poses a new way to promote crown ether compounds and alpha-ZrP materials, furthering their application in nuclear wastewater disposal, but also develops a new way of thinking about the design and preparation of new adsorbents for removal of difficult-to-capture ions from nuclear wastewater.