Amino Functionalized Urea-formaldehyde Framework Mesoporous Silica For U(?) Adsorption

Uranium wastewater from nuclear power plants as well as in situ and heap leaching of uranium mining can pollute the environment and endanger the health of humans and other living things.A mesoporous silica prototype(MSP) can be produced by attaching SiO2 colloids onto urea formaldehyde resin using a particular process.The data show that MSP is a mesoporous material, its specific surface area(683.64m2/g),average pore diameter, and total MSP pore volume decreased after grafting treatment.Using different grafting methods to treat MSP, we obtained three different amino functionalized mesoporous silica samples(i.e., APTES, TPDA and NNSO). We analyzed the materials with SEM, EDS, XPS, 13 C NMR, Zeta potential testing and N2 sorption/desorption isothermal experiments. We used Uv-vis and ICP-MS tests to investigate the sorption of U(VI) by each adsorbent under different pH conditions using different contact times and sorption isotherms.Our results suggested that all the adsorbents could remove uranyl sulphate almost completely in a 1:2,000 solid-liquid ratio with a 3.6 mg/L U(VI)concentration at pH 3.5–5.5. Uranyl carbonate was removed with a 3.6 mg/L U(VI) concentration at p H 6.5–9.5. The absorption equilibrium times were less than 30 min. The adsorption equilibrium curve was analyzed and the maximum sorption capacity was at pH 5.0. The strongest sample reduced the U(VI)concentration from 3.6 mg/L to 0.79 ?g/L with a removal rate of 99.98%. SiO2 colloids, such as D201, are used in U(VI) removal from aqueous solution. The MSP sample resembles SiO2 colloids and its adsorption ability and that ofD201 were therefore compared with the amino-functionalized mesoporous materials. The data suggested that the percentage U(VI) removed by the amino-functionalized mesoporous materials is much better than that of D201 resin in aqueous solutions of low U(VI) concentration and has a much larger capacity than MSP. In addition, 0.1 mol/L nitric acid could desorb U(VI) from the absorbent almost completely. In a continuity experiment,sorption–desorption cycles were performed 5 times, and the absorbent still remained at 60% of its full capacity.Our results suggest that amino functionalized mesoporous silica is an efficient, lost cost and renewable absorbent that can be used to remove U(VI)from aqueous solutions.