The Preparation And Uranium Adsorption Properties Of Porous Bio-derived Carbon And Its Complexes

With the shortage of fossil fuels and growing environmental concerns,nuclear energy,a green clean energy resource,has been continuously developed,and the demand of uranium?the raw material of nuclear energy?is also increased.Under the development of nuclear energy,the problem that is the shortage of the terrestrial uranium need to solve.While the oceans contain abundant uranium sources.Therefore,actively developing and designing new and efficient seawater uranium adsorption materials is conducive to the sustainable development of China's nuclear energy industry and has important strategic significance.Biomass-derived carbon materials have potential application value in the field of uranium extraction based on its environmental friendliness,high porosity,adjustable pore structure,chemical/thermal stability.In this paper,biomass carbon and waste orange peel were used as carbon sources to prepare porous carbon materials by high-temperature pyrolysis.And then,the prepared carbon materials were modified by chemical methods to fabricate composites for the treatment of uranium in aqueous phase.The desorption and reusability experiment,the ion competition experiment were carried out to assess the selectivity and recyclability property.Using cotton as a carbon source,Porous fibrous biomass carbon?CFA?was prepared by high-temperature two-step pyrolysis and chemical activation,and then oxidated by HNO₃ to synthesize carboxylated CFA?CFA-AO?.The adsorption performance of CFA-AO is improved after HNO₃ oxidation.The optimum adsorption pH of CFA-AO is 6.0.The adsorption process of uranyl ion followed the quasi-second-order kinetic model and Langmuir adsorption isotherm model.At 298.15 K,the maximum adsorption capacity of CFA-AO was 312.8 mg-g^-1.CFA-AO showed excellent recycling in a 5 cycle adsorption-desorption test.Combined with XPS analysis,it is speculated that the-COOH participates in coordination and the reduction of uranium by-CH₂OH.A three-dimensional porous carbon material?CDPC?was synthesized by high temperature carbonization and alkali activation using cotton as a carbon source,and aminated magnetic biomass carbon?CDPC/CoFe₂O₄-NH₂?was prepared by simple hydrothermal method.After compounding,the adsorption performance of CDPC/CoFe₂O₄-NH₂ is improved and the optimum pH value was 6.0.At 298.15 K,the maximum adsorption capacity of the prepared composite material was 413.8 mg g^-1.The distribution coefficient K_d value reached 15862 in ion competition test,which showed high selectivity and good recyclability after five cycles of desorption.The removal rate of uranium in simulated seawater could reach more than 80%.XPS analysis shows that metal oxygen and amino are involved in the electrostatic attraction of coordination and protonated amino to uranium.Orange peel is used as carbon source,three-dimensional porous magnetic activated carbon?MACs?are synthesized by high-temperature carbonization magnetization,and then AgNPs are loaded on the surface of MACs by the self-polymerization and reduction of dopamine to fabricate porous MACs/PDA-Ag composite.MACs/PDA-Ag has good adsorption performance,cycle stability and high selectivity in the offshore water pH?pH 8.0?.Adsorption isotherm data show that the maximum adsorption capacity is 603.2 mg^-1 at 298.15 K,The removal rate of uranium in simulated seawater could reach more than 90%and the anti-seaweed adhesion performance is good Combined with XPS and FT-IR analysis,functional groups such as amino,imino,metal oxide play an important role in the adsorption process.