Study On The Preparation Of Iron Oxyhydroxide (FeOOH) And Its Complexes And The Adsorption Properties Of Uranium

With the aggravation of environmental pollution and energy shortage,it is urgent to develop clean energy.Nuclear energy is a green,reliable and safe energy source,and uranium is an important raw material for nuclear energy.The rapid development of nuclear energy urgently needs to solve two problems,one is the shortage of uranium resources,uranium on the land reserves is limited,but the seawater contains a large amount of uranium resources.The other is the environmental pollution caused by the discharge of uranium-containing waste liquid,which is untreated discharge of uranium-containing waste into the environment will seriously damage the ecosystem and harm human health.Therefore,it is of great scientific and practical significance to actively carry out the research and development of adsorption material for extracting uranium from seawater and the treatment of uranium-containing waste liquid.Iron oxyhydroxide?FeOOH?is an important kind of iron oxide,which exists in a wide range of environmental media such as soil and sediments.It has potential applications value in seawater uranium extraction and uranium containing waste water treatment.In this paper,three kinds of high performance adsorbent materials for uranium extraction were synthesized with three different morphologies of FeOOH as substrates.The adsorption properties of uranium on synthetic materials under different experimental conditions?pH,time,temperature and concentration?were studied by static adsorption experiment system.Combined with adsorption kinetics model,adsorption isotherm model and thermodynamic function,the adsorption behavior of adsorbent was explored.At the same time,adsorption selectivity,desorption and cyclic regeneration of adsorbent were investigated.FeOOH hollow microboxes constructed from numerous 2D FeOOH nanosheets were successfully prepared by the template-engaged reaction.The synthesized product is lepidocrocite type?-FeOOH,with a regular cubic structure.Batch adsorption experiment results show that the optimum adsorption ph of FeOOH hollow microboxes was 8.0.The adsorption process accords with the pseudo-second-order model,and adsorption isotherm conforms to the Langmuir model and has excellent cyclic stability.The removal rate of uranium in simulated seawater is more than 90%,and it is an excellent adsorption material for seawater uranium extraction.Combined with XPS analysis,it is speculated that FeOOH adsorbed and immobilized uranium by means of Fe-O-UO₂²⁺and hydrogen bonds.The 3D flower-like FeOOH nanomaterials were synthesized by coprecipitation method.The amidoxime polyacrylonitrile/FeOOH composite?FeOOH/APAN?was prepared by in-situ emulsion polymerization using FeOOH as the substrate.Compared with FeOOH,FeOOH/APAN has higher adsorption capacity.The adsorption isotherm conforms to the Langmuir model,and the adsorption kinetics is better in accordance with the pseudo-second-order model.It has excellent adsorption selectivity for uranium and the removal rate of FeOOH/APAN for simulated seawater is more than 92%.By XPS analysis,it is speculated that the oxime oxygen and oxime nitrogen in the amidoxime group are involved in the coordination with uranium.It is suggested that the?² coordination may be the main way for the combination of FeOOH/APAN and uranium.The urchin-like FeOOH hollow microspheres were prepared by solvothermal method,and then combine with polyethyleneimine?PEI?to obtain the FeOOH/PEI adsorbents.The optimum adsorption pH of this material was 7.0.The adsorption kinetics accords with the pseudo-second-order model,and the adsorption isotherm conforms to the Langmuir model.It has good cycling stability and adsorption selectivity.In the adsorption test near the real seawater environment,it was found that FeOOH/PEI has outstanding removal rate for low concentration of uranium.According to XPS analysis,the amine group plays an important role in the uranium adsorption process,and the adsorption of uranium is achieved through electrostatic interaction/hydrogen bonding and complexation.