Zhuo Dai Li,Huai Qiang Zhang,Xiao Hong Xiong,Feng Luo
Covalent organic frameworks (COFs) represent an exciting new type of porous organic materials, which are constructed with organic building units via strong covalent bonds . Here in, the COF-2,4,6-Triformylphloroglucinol p-Phenylenediamine (COF-TpPa-1) was synthesized by solvothermal method for the removal of U(VI) from aqueous solution. Effects of pH, adsorption dose, contact time, uranium solution concentration, temperature and adsorption and desorption cycle on the efficiency of COF-TpPa-1 removal of U(VI) are investigated. SEM, XRD , TGA and FT-IR were employed to characterize the samples and analyze adsorption mechanism. The results manifested COF-TpPa-1 has the high adsorption capacity ( q m = 152 mg/g), quick adsorption kinetic , high selectivity , outstanding recycle performance and good resistance to acids, bases and high temperature.
The spinel composite doped with TiO 2 (TiO 2 @ZnFe 2 O 4 ) was prepared via in situ fabrication and template method to extract uranium(VI) from solution. Compared with ZnFe 2 O 4 and TiO 2 /ZnFe 2 O 4 , TiO 2 @ZnFe 2 O 4 showed a high adsorption efficiency (98.3%) and adsorption capacity (716.2 mg g −1 ), which mainly related to the uniform porous structure of TiO 2 @ZnFe 2 O 4 . After five adsorption–desorption cycles, the removal efficiency of TiO 2 @ZnFe 2 O 4 remained above 90%, indicating that TiO 2 @ZnFe 2 O 4 had excellent reusability. Besides, TiO 2 @ZnFe 2 O 4 possessed excellent adsorption selectivity for uranium(VI) in the existence of competitive ions. The Langmuir adsorption model and pseudo-second order model fitted well the adsorption process, which demonstrated that the remove behavior of uranium(VI) on TiO 2 @ZnFe 2 O 4 was a monolayer chemisorption process. The extraction behavior of TiO 2 @ZnFe 2 O 4 for uranium(VI) was mainly attributed to electrostatic attraction, complexation reaction and oxygen vacancy filling. This study not only provides a high efficiency adsorbent (TiO 2 @ZnFe 2 O 4 ) for the extraction of uranium(VI) from solution but also offers a new effective way to enhance the performance of spinel composite.
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