Efficient extraction of uranium(VI)from aqueous solution by Zr/Ce-UiO-66-NH_(2) modified by dual strategies of bimetallization and amination

We modified Zr/Ce-UiO-66-NH_(2) using dual bimetallization and amination strategies to efficiently extract uranium from water resources.XRD,FTIR,and XPS indicated the successful alteration of material amination.Moreover,the metal Zr was partially replaced by Ce in Zr-oxygen atom clusters in Zr/Ce-UiO-66-NH_(2).It possessed commendable structural stability in acidic and alkaline solutions.Irrespective of whether it was submerged in a 6 M strong acid or in a 0.5M strong base solution,the structural integrity of Zr/Ce-UiO-66-NH_(2) remained unaffected.Batch experiments at pH=6.0 revealed that uranium adsorption by Zr/Ce-UiO-66-NH_(2) reached 376.8 mg g^(−1) and 611.33 mg g^(−1) at 298 K and 328 K,respectively.These values are much better than those obtained using bimetallic-modified Zr/Ce-UiO-66 or amine-functionalized UiO-66-NH_(2).After five consecutive sorption and desorption cycles,the material retained a uranium removal rate of more than 80%,proving its excellent regenerative properties.Kinetic modeling of U(VI)adsorption on Zr/Ce-UiO-66-NH_(2) implied that chemisorption dominated the rapid uranium sorption rate.We propose potential adsorption mechanisms involving three interactions:inner-sphere surface complexation,chemisorption,and electrostatic interactions.This study shows that the dual strategies of bimetallization and amination can effectively enhance U(VI)extraction from water.This approach has potential applications for the structural design of uranium adsorbents.

Polymer-coated nanoporous carbons for trace seawater uranium adsorption

Polymer-coated mesoporous carbon nanocomposites were prepared from the immobilization of acrylonitrile and acrylic acid copolymers with divinylbenzene as a crosslinker onto a mesoporous carbon framework.High surface areas were maintained after polymerization with accessible porosity.This functional nanocomposite was tested as an adsorbent for uranium from high salinity solutions.Uranium adsorption results have shown that the adsorption capacities are strongly influenced by the density of the amidoxime groups and the specific surface area.

Radiation-induced one-pot synthesis of grafted covalent organic frameworks

Post-synthetic functionalization of covalent organic frameworks(COFs)is an alternative way to enhance and broaden their properties and potential applications.However,the chemical functionalization of COFs is a great challenge because traditional procedures are often time-and energy-consuming,while the crystallinity of COFs can be damaged under harsh conditions.Here we report the in-situ introduction of functional graft chains onto the skeleton of COFs during the synthesis process through the combination of radiation-induced synthesis and graft polymerization techniques under ^(60)Co gamma-ray radiation.The synthesis and functionalization of COFs are simultaneously accomplished in a chemical system under ambient conditions yielding a large number of different functionalized COFs.The obtained carboxyl-functionalized COFs exhibit excellent radioactive uranium removal capabilities from aqueous solution with fast uptake dynamics,high adsorption capacity,and excellent selectivity over other competing metal ions.

A sorbent of expanded rice husk powder for removal of uranyl ion from aqueous solution

A novel sorbent for the removal of uranyl ion was prepared by expanded rice husk powder. Batch adsorption experiments were performed on factors of p H,temperature, initial uranyl ion concentration, adsorbent dosage and contact time to evaluate the adsorption capacity. The results show that the saturation adsorption capacity is 5.7 mg·g^-1 using expanded rice husk powder treating uranyl ion aqueous solution（80 mg·g^-1） for 24 h at 25 ℃ with initial pH3. Adsorption process could be well described by Langmuir isotherm model. The adsorption kinetic data are fitted well with pseudo-second-order model. The results obtained show that expanded rice husk adsorbent is a promising adsorbent for the removal of uranium from aqueous solutions.

Synthesis of hierarchical mesoporous Ln_(2)Ti_(2)O_(7)(Ln=Y,Tb-Yb)pyrochlores and uranyl sorption properties

Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,high temperatures are required which inhibit control of pore structure properties including surface area,pore volume,and pore size.Herein,the synthesis of ternary metal oxides Ln_(2)Ti_(2)O_(7)pos-sessing pyrochlore crystal structure is achieved using a novel technique which combines‘soft’and hard colloid templating strategies.The formed materials are of submicron size and composed of∼25-30 nm product‘building blocks’with good chemical and phase stability.The polycrystalline powders have a high specific surface area(up to 70 m^(2)·g^(-1))and pore volume(∼0.35 cm^(3)·g^(-1))which result in a good adsorp-tion capacity(U uptake closing to 60 mg·g^(-1)).Remarkably,the material exhibits a significant portion of mesopores(mainly 10-40 nm)which facilitate fast adsorption of the cations due to high accessibility.The synthetic methodology described herein produces highly homogenous powders and can be applied to other compositions and structures.