Synthesis Of Carboxylation Calix [4] Arene Derivatives And Its Adsorption Properties Towards Uranium(Ⅵ)

Nuclear energy as a safe and environmentally friendly new energy has been gained more and more attention.However,as the main fuel of nuclear energy,uranium is not only chemically toxic to heavy metals but also radioactive.Therefore,it is an urgent and arduous task to study new functional materials to remove and treat uranium in radioactive wastewater in order to reduce the harm to human health and ecological environment.Calixarene is macrocyclic compounds formed by phenol units through methylene bridging,which have the ability to recognize molecules（ions）.By functionalizing the upper and lower rim of calixarene and introducing functional groups with special functions,the selective recognition of target metal ions can be realized.Therefore,the synthesis and application of calixarene derivatives have become a hotspot in this field.Basing the characteristic that p-tert-butyl calix[4]arene can highly match the spatial coordination configuration of UO₂²⁺.In this paper,using the p-tert-butyl calix[4]arene as raw materials,two new functional materials carboxylation calix[4]arene derivatives were obtained.The carboxylation calix[4]arene derivatives were characterized by FT-IR,SEM and NMR.The main research contents and conclusions of this paper are as follows:（1）The p-tert-butyl calix[4]arene was synthesized by using HCHO and p-tert-butylphenol as raw materials.Then,using the p-tert-butyl calix[4]arene,m-aminobenzoic acid and 1,3-dibromopropane as raw materials,A new type of functional material M-carboxyphenylazo calix[4]arene bromine diethyl ether Derivatives（MCA-BDED）was obtained.The structure of MCA-BDED was characterized by FT-IR and SEM.The effects of pH value of U（VI）solution,adsorption time,initial uranium concentration,temperature,dosage of adsorbent on the adsorption of uranium on MCA-BDED were investigated,finally the reaction kinetics and adsorption isotherm were analyzed.Results show that the best condition of uranium adsorption are as follows.pH value is4.0,initial concentration of uranium is 20 mg/L,dosage of adsorbent is20 mg,adsorption equilibration time is 4 hours at 25℃and the best temperature is 30℃.The adsorption kinetics of MCA-BDED to uranium was accorded with pseudo-second order model which shows that the adsorption process is chemical adsorption.The adsorption process which is better fitted with Langmuir,and Freundlich sorption isotherm was chemisorption.It suggested that the adsorption system was a model of single-layer coverage combined with multilayer adsorption.In addition,MCA-BDED has good regeneration properties,because the adsorption rate is over 60%after three times of desorption and regeneration with three different desorption agents.（2）Using the p-tert-butyl calix[4]arene,p-aminobenzoic acid,NH₂OH·HCl,3,3’-Iminodipropionitrile as raw materials,A new type of functional material p-carboxyphenyl Azo Calix[4]arene Amine oxime Derivatives was obtained.The structure of p-carboxyphenyl Azo Calix[4]arene Amine oxime Derivatives was characterized by FT-IR SEM and ¹H-NMR.The effects of pH value of U（VI）solution,adsorption time,initial uranium concentration,dosage of adsorbent on the adsorption of uranium on p-carboxyphenyl Azo Calix[4]arene Amine oxime Derivatives were investigated,finally the reaction kinetics was analyzed.Results show that the best condition of uranium adsorption are as follows.pH value is 4.0,initial concentration of uranium is 10 mg/L,dosage of adsorbent is 10 mg,adsorption equilibration time is 5 hours at 25℃.The adsorption kinetics of p-carboxyphenyl Azo Calix[4]arene Amine oxime Derivatives to uranium was accorded with pseudo-second order model which shows that the adsorption process is chemical adsorption.In addition,p-carboxyphenyl Azo Calix[4]arene Amine oxime Derivatives has good regeneration properties,because the adsorption rate is over 70%after three times of desorption and regeneration with three different desorption agents.