Americium(III) Capture Using Phosphonic Acid-Functionalized Silicas with Different Mesoporous Morphologies: Adsorption Behavior Study and Mechanism Investigation by EXAFS/XPS

Abstract

Efficient capture of highly toxic radionuclides with long half-lives such as Americium-241 is crucial to prevent radionuclides from diffusing into the biosphere. To reach this purpose, three different types of mesoporous silicas functionalized with phosphonic acid ligands (SBA-POH, MCM-POH, and BPMO-POH) were synthesized via a facile procedure. The structure, surface chemistry, and micromorphology of the materials were fully characterized by (31)P/(13)C/(29)Si MAS NMR, XPS, and XRD analysis. Efficient adsorption of Am(III) was realized with a fast rate to reach equilibrium (within 10 min). Influences including structural parameters and functionalization degree on the adsorption behavior were investigated. Slope analysis of the equilibrium data suggested that the coordination with Am(III) involved the exchange of three protons. Moreover, extended X-ray absorption fine structure (EXAFS) analysis, in combination with XPS survey, was employed for an in-depth probe into the binding mechanism by using Eu(III) as a simulant due to its similar coordination behavior and benign property. The results showed three phosphonic acid ligands were coordinated to Eu(III) in bidentate fashion, and Eu(P(O)O)3(H2O) species were formed with the Eu-O coordination number of 7. These phosphonic acid-functionalized mesoporous silicas should be promising for the treatment of Am-containing radioactive liquid waste.

Highly Selective Recovery of Lanthanides by Using a Layered Vanadate with Acid and Radiation Resistance

“…Generally,amaterial is considered as an excellent adsorbent if K d is over 10 4 mL g À1 .P articularly, K d Eu was up to 1.73 10 5 mL g À1 (99.43 %r emoval rate) at pH 2.6. Such high K d indicate that 1 has obviously higher affinity toward Eu 3+ than reported silica-phosphonic acid, [28] activated carbon [27] and ZSM-5 zeolite [13] (Supporting Information, Table S8).…”

“…[11] Thes trongly acidic high-level radioactive liquid wastes (HLLW) put forward higher request on the adsorbents for lanthanide ions. [4a] At present, many adsorbents for Eu 3+ removal, such as silica-phosphonic acid [28] and PUR foam @HTTA [29] are greatly limited because of low capacity or failure to adsorb Eu 3+ in acidic conditions.Itishighly needed to develop new adsorbents that could the efficiently recover lanthanide ions from the complex wastewater for radionuclide remediation. Therefore,t he Eu 3+ adsorption for 1 in acidic solutions was systematically studied.…”

Development of novel nanomaterials for remediation of heavy metals and radionuclides in contaminated water

“…Three types of phosphoric acid modified silica, SBA-POH, MCM-POH, and BPMO-POH, were employed for the sorption of Am(III) and Eu(III) [94]. The coordination number was obtained from EXAFS.…”

Study on the gamma-ray irradiation behavior of mesoporous silica adsorbents functionalized with phosphine oxide and phosphonic acid ligands

“…Due to the remarkable coordination ability to fission products, organophosphorus compounds like TBP [11], TRPO [12] and Cyanex 272 [13] have been widely used in the solvent extraction processes in nuclear industry [14]. In our previous research, we reported the functionalization of mesoporous silicas with organophosphorus ligands, including neutral alkyl phosphine oxide [15] and acidic phosphonic acid derivatives [16], for actinides adsorption. And the results showed that the adsorbents were promising for the efficient separation of radionuclides in nuclear fuel cycles.…”