Preparation Of Magnetic Functionalized Calix [4] Arene Composites S And N Derivatives And Their Adsorption For Uranium

In recent years,with the rapid development of the nuclear industry,a large number of uranium-containing wastewater has been discharged into the environment.Uranium exists mainly in the form of uranyl-ion(UO₂²⁺)in uranium-containing wastewater,which has high solubility and mobility.Improper treatment of uranium-containing wastewater poses a long-term threat to human health and biodiversity.Therefore,the separation and enrichment of uranium is crucial to environmental safety.Calixarene is a cyclic oligomer whose derivatives have been proven to be excellent adsorbents for removal removing U?VI?.However,it is difficult to separate these adsorbents from aqueous solutions because of their tiny particle size,which can cause secondary contamination.In recent years,with the development of nanotechnologies,magnetic separation has been applied to environmental decontamination.Therefore,by combining the adsorbent with magnetic materials,the adsorbent cannot only retain the high adsorption capacity,but also acquire the paramagnetism of the magnetic materials.In this paper,Calix[4]arene were modified by carboxylation on the upper rim and S and N groups on the lower rim,and then combined with magnetic nano-Fe₃O₄,the magnetic functional composites with stereoscopic conformation stability were prepared.The composite were characterised by FT-IR,¹H-NMR,SEM and XRD.In order to test their adsorption properties for uranyl ions,we systematically studied their adsorption behavior under different conditions.The main contents and conclusions of this paper are as follows:?1?A series of m-carboxyphenyl azo calix[4]arene derivative was successfully synthesized by diazotization and coupling reaction from m-Aminobenzoic acid as raw material.The calix[4]arene derivative was characterized by FT-IR and ¹H-NMR.The effects of pH value,adsorbent dosage,contact time,temperature and related parameters on adsorption of U?VI?by M-carboxyphenyl azo calix[4]arene derivative were investigated.The results of the investigation show that the initial pH is 4.0,the dosage of adsorbent is 8 mg,the initial concentration of uranium is 20 mg/L,the adsorption time is 3.0 h and the temperature is 25?,the adsorption rate of U?VI?by M-carboxyphenyl azo calix[4]arene derivative reaches the maximum.The adsorption process is endothermic and conforms to the quasi second order chemical kinetics model.In addition,after several cycles of experiments,the adsorbent can be found to have good regeneration.?2?The magnetic functional composites were prepared by grafting S and N groups on the lower edge the lower rim of M-carboxyphenyl azo calix[4]arene derivative,and then the novel magnetic functionalized composite consisting of Fe₃O₄ and calix[4]arene derivative was prepared through a facile self-assembly method,and used to extract U?VI?from aqueous solution.The results show that the adsorbent material has good adsorption properties for U?VI?.When the pH is 5.0,the initial concentration is 20 mg/L,the temperature is 25?,the contact time is 4 h and the dosage of adsorbent is 8 mg in the equilibrium adsorption experiments,the adsorption rate of U?VI?by the adsorbent material reaches the maximum.The thermodynamic data indicate that the process of extracting uranium is spontaneous and endothermic.The adsorbent material also has good repeatability and selectivity for the adsorption of U?VI?.