Biomass-supported Monodisperse N-Fe~0@M~ 0preparation And Basic Research On Application Of Uranium Adsorption And Reduction

Extensive research on nuclear fuel and military projects has promoted the development of uranium resources,while uranium-containing wastewater is produced in this process.However,the treatment of uranium-containing wastewater is still a difficult problem.The main forms of uranium in solution are U（IV）and U（VI）,among which U（IV）easily forms stable complexes,while U（VI）exists in the form of UO₂²⁺.Therefore,reducing U（VI）to U（IV）is an effective method to realize the separation of uranium in aqueous solution and to treat uranium-containing wastewater,that is,to convert UO₂²⁺ions into complex precipitation.In this paper,tannery waste collagen fibers,plant polyphenols,and expired honey to burn hydrothermal charcoal are used as carriers,successfully dispersed the highly reducing nanoparticles NZVI,which are easy to agglomerate and easy to oxidize.The adsorption and reduction characteristics of U（VI）in simulated uranium-containing wastewater are explored.Its adsorption effect on the process and its potential application value.The results of the studies are listed as follows:（1）Collagen fiber solidified bayberry tannin loaded with nano zero-valent iron-nickel bimetallic adsorbent（NZFNP）and are used to simulate the static adsorption of uranium-containing wastewater.When 0.02 g of HHC-FTNP with the initial concentration of uranium is 20 mg·L^-1,and the p H range from 2 to 6,the optimal adsorption capacity is 49.0 mg·g^-1,and the removal rate reaches 98%;when 0.02 g of HHC-FTNP with the initial concentration of uranium is 20 mg·L^-1 and the p H value is 5,the reaction reached equilibrium within 300minutes,and the fitting of Langmuir isotherm adsorption model and pseudo-second order Kinetic linear model adsorption reduction process conforms that high temperature contributes to the process of the reaction,the adsorption and reduction process of U（VI）by NZFNP is mainly the chemical reaction of the monomolecular layer.Through characterizations such as SEM,TEM,FTIR,XPS,etc.,it is shown that nano-zero-valent iron is successfully dispersed on collagen fibers and Fe⁰ is preserved,and on the NZFNP after adsorption and reduction is calculated that the element uranium adsorbed on its surface exceeds up to 70%are U（IV）,which means that NZFNP has a strong reducibility to U（VI）adsorbed in water.（2）Hydrolyzed collagen solidified bayberry tannin loaded with nano zero-valent iron-nickel bimetallic adsorbent（H-NZFNP）and it is applied to the static adsorption of simulated uranium-containing wastewater.On the bases of the previous NZFNP,in view of the low adsorption capacity of NZFNP,more hydrogen bonds are opened after the collagen is hydrolyzed by Na OH,which effectively improves its ability to solidify bayberry tannins,thereby increasing its ability of loading nano-zero-valent iron-nickel metal.The static adsorption results of H-NZFNP used to treat simulated uranium-containing wastewater show that the optimal parameters such as p H,time,and feed amount for U（VI）adsorption and reduction by H-NZFNP are consistent with NZFNP,and the reaction also conforms to the Langmuir isotherm adsorption model and pseudo-second-order kinetic linear model,temperature promotes the reaction and the adsorption and reduction process of U（VI）by H-NZFNP is also dominated by the chemical reaction of the monolayer.However,on this basis,the adsorption capacity of H-NZFNP for U（VI）has been significantly improved,from the maximum adsorption capacity of NZFNP of 129.3 mg·L^-1 to the adsorption capacity of H-NZFNP of 400 mg·L^-1.（3）Nano-iron-titanium bimetallic particles（FTNP）was NZVI modified on the surface by titanium and applied to the static adsorption of simulated uranium-containing wastewater.Aiming at the problem that the role of metallic nickel in the supported nano-zero-valent iron-nickel bimetallic particles is not obvious,this part uses metallic titanium to modify the surface of nano-zero-valent iron and obtains good experimental results.The static adsorption results of FTNP show that when the initial concentration of uranium is 20 mg·L^-1,the dosage is 0.01g,and the p H range is 3-10,the optimal adsorption capacity is 98.0 mg·g^-1 and the removal rate in this p H range ware all higher than 90%.At the same time,NZVI,which has not been surface-modified by metallic titanium,can only achieve 90%removal rate in the p H range of3-5.The process of FTNP adsorption and reduction of U（VI）basically reached equilibrium within 180 min and conformed to the Freundlich isotherm adsorption model and the pseudo-second-order kinetic model.（4）The honey hydrothermal carbon is loaded with nano zero-valent iron-titanium bimetallic nanoparticles（HHC-FTNP）and was applied to the adsorption study of simulated uranium-containing wastewater.The carrier of honey charcoal improves the dispersibility of FTNP,and the results of adsorption reduction experiments show when 0.02 g of HHC-FTNP with the initial concentration of uranium is 20 mg·L^-1,and the p H value is 5,the process of HHC-FTNP adsorption and reduction of U（VI）reaches equilibrium within 180 minutes,and the overall removal rate is within 180 minutes.More than 70%of uranium was adsorbed,which means HHC-FTNP is with potential application prospects.