Study Of Mof For U(?) Detection,Adsorption And Photocatalysis

Uranium is an important strategic resource,which not only plays an irreplaceable role in the nuclear industry,but also plays an important role in the military,agriculture and many scientific fields.At the same time,uranium is also a toxic radioactive element.It not only brings convenience to human beings,but also harms the environment of the water system and human health.In order to better develop clean energy,it is necessary to develop a material that can detect and adsorb uranium at the same time.In addition,the uranium resources on land are limited and cannot meet the long-term needs of mankind.In contrast,the amount of uranium in seawater is 1000 times that of land,so the development of an adsorption material which can be extracted from seawater has a very important application prospect.At the same time,uranyl is used as a metal node and different organic ligands to synthesize uranium-organic framework materials to explore the properties of uranyl organic frameworks(UOFs),which can also provide guidance for the treatment of nuclear waste in the nuclear industry.This thesis focuses on the detection,adsorption and photocatalysis of uranium in solution based on MOF material.The results are as follows:1.A fluorescent zinc-based metal-organic skeleton(HNU-50)was designed and synthesized for the effective detection and adsorption of U(VI).The amide groups on N-(4-pyridyl)isonicotinamide ligands and two uncoordinated carboxyl oxygen atoms on pyromellitic acid ligands in HNU-50 provide potential uranium binding sites.Therefore,HNU-50 can selectively and efficiently capture uranyl ions,and the optimum adsorption capacity is 632 mg/g.In addition,the adsorption of U(VI)leads to the fluorescence quenching of HNU-50,thus realizing the sensitive and selective fluorescence detection of U(VI).It is worth noting that the detection limit of HNU-50for U(VI)in aqueous solution is extremely low,which is 1.2x10^-8M,which is lower than the highest pollution standard of the World Health Organization for drinking water(6.3x10^-8M).2.Amino oxime functionalized ZIF-90 molecular sieve,named ZIF-90-ABOA,was synthesized by grafting 4-aminobenzamide oxime.Due to the high chelating ability of amidoxime to uranium,ZIF-90 showed excellent adsorption properties for U(VI).The maximum adsorption capacity of 353.4 mg/g,for uranium in aqueous solution is twice that of the original ZIF-90.In addition,the adsorption capacity of trace uranium in real seawater can reach 2.8 mg/g,which proves the potential enrichment of radioactive uranium in practical application.3.A new type of recyclable photocatalytic adsorbent based UOF was synthesized by solvothermal method,named PVP@UOF@CNTs(PVP:polyvinylpyrrolidone,UOF:U-MOF based on porphyrin,CNT:carbon nanotube).Due to the doping of CNTs and PVP,the stability of UOF was greatly improved.After soaking in water for three days,PVP@UOF@CNTs could maintain good crystallinity.Then,we studied the adsorption and photocatalytic performance of PVP@UOF@CNTs,and the maximum adsorption capacity of tetracycline was 43.4mg/g,and the degradation of tetracycline reached 78%.These results provide a new method for the synthesis of stable actinides metal MOF photocatalytic adsorbents,which can effectively remove tetracycline antibiotics and other pollutants in wastewater.