Removal Of U(Ⅵ) By Multi-Titanate

As an emerging clean energy,nuclear energy has the risk of leakage,causing radioactive pollution.At the same time,with the development of industry,people use a large number of organic materials,which will also bring adverse effects on the environment.With the improvement of social influence and public environmental awareness,the pollution of organic pollutants and radionuclides to the environment has aroused people’s great attention,and finding and developing efficient removal methods become a top priority research spot.In order to overcome the above shortcomings and meet the energy demand,researchers have discovered many methods,such as adsorption,photocatalysis,and electro-catalysis,etc.Among all the above mentioned methods,adsorption and visible light catalysis technologies have attracted great interest in recent years because of their energy saving and high efficiency merits.Titanium dioxide has been studied more abundantly and deeply.However,as a new nanomaterials with similar crystal structure to TiO₂,layered titanates have been reported rarely as adsorbent or photocatast for the treatment of environmental pollutants,especially the lack of reports on the efficient adsorption or photocatalytic nanomaterials.In this study,two materials C@KTO and GO/KTO were prepared by a simple hydrothermal method,and the adsorption and photocatalytic reactions with organic matter and radionuclides were investigated.The main methods and conclusions are as follows:1)C@TiO₂ has been used as a precursor,via a simple hydrothermal method,to successfully fabricated C@KTO layered nanomaterials.C@KTO HNM is constructed by loading KTO nanoribbons on the surface of carbon balls.The U（VI）and RhB are removed by C@KTO HNMs from the water solution efficiently by adsorption.The effects of initial pH,adsorption time,existing ions and ionic strength have been systematically studied.A bout 90%of Rh B and 100%of U（VI）can be removed by C@KTO HNMs within 1 hour.C@KTO HNMs,as a low-cost,low-toxic,and effective adsorbent,has huge application potential in environmental management.2)In another research,KTO nanobelts were hybridized on the surface of GO nanosheets for the photodegradation of RhB（dye）and photoreduction of U（Ⅵ）（radionuclide）through a simple hydrothermal method.The adsorption capacity and the first order kinetic constant of photocatalysis of RhB are found both higher than that of GO and KTO.In the presence of different free radical.scavengers,it was found that superoxide radicals（·O₂-）played a dominant role in the reaction.XPS experiments show that U（Ⅵ）has been successfully photoreduced to less toxic U（Ⅳ）.Both the pH-dependent photocatalysis experiments of RhB and U（Ⅵ）showed the best performance at neutral pH value（from pH 6 to pH 8）.In order to further study the mechaisms for the enhanced photocatalysis of GO/KTO,its morphology/microstructure,optical and photoelectrochemical properties were studied.The enhancement of photoelectron and hole separation ability and GO/KTO adsorption ability are attributed to the combination mode of KTO nanoribbons on the surface of GO nanosheets,which can maximize the contact area between KTO and GO,thereby greatly reducing surface-related oxygen defects and enhance the electronic interface transfer between KTO and GO.These results show that GO/KTO can have excellent treatment potential for organic pollutants and high valent radionuclide ions under neutral conditions.