Preparatiom Of Novel Functionalize Biological Adsorbent And Adsorption Of Uranium

Uranium is a very important strategic resource in the field of nuclear power industry and nuclear technology,and it is also a kind of radioactive heavy metal element.During the development and utilization of uranium,a large number of uranium containing wastewater has been generated,which endangers the ecological environment and human health.Therefore,the treatment of low concentration uranium wastewater is attracting more and more attention.Nano-Fe3O4 is a kind of magnetic nanomaterials which is easy to be prepared and cheap,the amidoxime group has high selectivity and affinity for uranium ions,Aspergillus niger is an environmental friendly pro-uranium biological materials.It is clear that the combination of the three is expected to build an economically,highly efficient,environmentally friendly biosorption material for the efficient treatment of low-concentration uranium in wastewater,so in this study,the Aspergillus niger magnetic bioadsorbent NFAN(Nano-Fe3O4 modified Aspergillus Niger,NFAN)and ANFAN(Amidoxime modified Nano-Fe3O4-Aspergillus niger)were prepared by the Aspergillus niger and nano-Fe3O4 and amidoxime group.In the chapter 2,the influence of initial pH value,adsorption time,adsorbent dosage,temperature and initial concentration of uranium on uranium adsorption by NFAN was studied,analyzed the kinetic and thermodynamics of the adsorption process,and analyzed the mechanism of uranium by scanning electron microscopy(SEM),energy spectrum and Fourier infrared spectrum(FT-IR).The results show that :the initial pH value was 7,the adsorption time was 240 min,the adsorbent dosage was 0.15 g·L-1,the maximum adsorption efficiency by NFAN for 6 mg/L U(VI)solution amounted to 76.36% under the optimum adsorption conditions,and the maximum biosorption capacity of NFAN for U(VI)was estimated to be 60.05mg/g.The SEM results showed that uranium adsorption and deposition on the surface of NFAN were observed during the adsorption process.As shown by SEM-EDS diagram,NFAN mainly contained O,C,Fe,P and other elements.After adsorption uranium,the surface uranium content accounted for 27.72%,indicating that NFAN has good adsorption effect on low concentration uranium.The analysis of infrared spectrum(FTIR)showed that-OH,-COOH,C=O and-N-H on the surface of adsorbent were the main adsorption sites during the adsorption of uranium.The adsorption kinetics was better depicted by pseudo-second-order kinetic model in the adsorption of uranium by NFAN.The thermodynamic investigations showed that the process of U(VI)adsorption was feasible spontaneous,and endothermic.In the chapter 3,the influence of initial pH value,adsorption time,adsorbent dosage,temperature and initial concentration of uranium on uranium adsorption by ANFAN was studied,analyzed the kinetic and thermodynamics of the adsorption process,and analyzed the mechanism of uranium by scanning electron microscopy(SEM),energy spectrum and Fourier infrared spectrum(FT-IR).In addition,the stability,reusability and economic efficiency of the ANFAN were investigated by the experiment of desorption and regeneration.The results show that under the optimum adsorption conditions that the initial pH value was 5,the adsorption time was 240 min and the solid-liquid ratio was 0.25g·L-1,the maximum adsorption efficiency of ANFAN for 6 mg/L U(VI)solution amounted to 92.35%,and the maximum biosorption capacity reached 23.38mg/g.The SEM results showed that the ANFAN after the adsorption of uranium became rough and dense,which was presumed to be related to the adsorption and deposition of uranium on the ANFAN surface.According to SEM-EDS diagram,ANFAN contains O,Fe,C,Cl and other elements.After adsorption uranium,the surface uranium content is 5.34%,which indicates that ANFAN has good adsorption effect on low concentration uranium.The analysis of infrared spectrum(FTIR)showed that-OH,-COOH,C=O and-N-H on the surface of adsorbent were the main adsorption sites during the adsorption of uranium.The adsorption kinetics was better depicted by pseudo-second-order kinetic model,indicated that chemical adsorption is the main control step of the adsorption rate in the adsorption of uranium by ANFAN.The adsorption equilibrium data fitted the Langmuir isotherm model well which indicated that the adsorption of uranium on ANFAN was a single layer of chemical adsorption.The thermodynamic investigations showed that the process of U(VI)adsorption was feasible spontaneous,and endothermic.The regeneration experiment showed that only a few loss during the adsorption process,indicated that ANFAN had good ability to adsorb low concentration of uranium and reutilization performance.In this paper,the preparation of NFAN and ANFAN combined the magnetic properties of Fe3O4 nanoparticles,pro-uranium properties of Aspergillus niger,and the high adsorption capacity of the amidoxime group,provides a large adsorption capacity,adsorption speed,low production cost,high mechanical strength,high selectivity,easy recovery of the new magnetic biosorbent preparation the adsorption of low concentration uranium and its method.