Adsorption Of U(?) From Aqueous Solution By Type Of Easily Solid-liquid Separated Graphene Oxide Nanoribbons Composite Materials

In order to achieve a green and sustainable development strategy,China needs to vigorously develop clean energy,mainly including nuclear power.Uranium is the main nuclear fuel used in nuclear power plants,but various kinds of uranium-containing radioactive waste-water are produced in uranium mining,nuclear fuel manufacturing and spent fuel reprocessing.The separation,enrichment and recovery from uranium-containing radioactive waste-water is of great significance to the sustainable development of nuclear energy,environmental protection and human health.As a new member of the carbon nanomaterial family,graphene nanoribbons(GNRs)have the excellent properties of both CNTs and graphene.At present,it is applied to the field of wastewater treatment.However,powdered carbon nanomaterials as adsorbents have the problem of difficult separation in practical applications and nano toxicity.The secondary pollution caused by this imposes restrictions to its application in adsorption.In this paper,Multi-walled carbon nanotubes(MWCNTs)were longitudinal unzipping to form graphene oxide nanoribbons(GONRs)by KMn O₄ and H₂SO₄.Magnetic functionalization and gelation were used to prepare two materials that facilitated solid-liquid separation.It was characterized by SEM,FT-IR,XRD,and TEM.Adsorption behaviors of U(?)on three kinds of materials were investigated by varying pH,adsorbent dosage,contact time,U(?)initial concentration and temperature.The main results are as follows:(1)Synthesis of GONRs for the Removal of U(?)from Aqueous SolutionsThe oxygen-containing groups in GONRs not only could greatly improve the adsorption capacity,but also could provide favorable conditions for functionalization.The maximum sorption capacity of U(VI)on GONRs was 394.1 mg·g^-1,which was much higher than any of currently reported carbon-based nanomaterials.The adsorption process was pH-dependent,endothermic and spontaneous and it could be effectively regenerated.GONRs could be a promising candidate for the removal and recovery of uranium from aqueous solutions.(2)Synthesis of Magnetic Graphene Oxide Nanoribbons(MGONRs)Composite for the Removal of U(?)from Aqueous SolutionsThe magnetic beads were successfully loaded on the surface of the GONRs by the hydrothermal method,and MGONRs was able to realize rapid solid-liquid separation under an external magnetic field.The maximum sorption capacity of U(VI)on MGONRs was122.2 mg·g^-1.The adsorption process was a single-layer chemical adsorption.The adsorption process was more favorable at higher temperature and it could be effectively regenerated.(3)Synthesis of GO/GONRs Composite Aerogel for the Removal of U(?)from Aqueous SolutionsGO/GONRs composite aerogels for solid-liquid separation were prepared by reduction self-assembly and freeze-drying methods.The maximum sorption capacity of U(VI)on MGONRs was 295.11 mg·g^-1.The adsorption process conformed to Freundlich,internal diffusion model and quasi-secondary kinetic model,and belonged to two adsorption processes:surface adsorption and slow diffusion in the pore channel.