| Beta-cyclodextrins(β-CD) is cone-shaped cyclic oligosaccharidesconnected by a consisting of seven D-glucopyranose in sequence, they have different sizes of hydrophobic cavity, hydrophilic outer surface and chiral properties, so they have been widely applied in many fields of science and technology. However, thebonding effect of natural cyclodextrins and substrate molecules is relatively weak, which limited the application of them.In order to improve the application value of natural cyclodextrins, it is necessary to carry out some chemical modification to natural cyclodextrins.The hydrophobicity and the cavity size of modified cyclodextrins havebeen changed, which expand the scope of application of cyclodextrin. In recent years, the research on bridged β-cyclodextrins isvigorous development. As a new type of cyclodextrin derivatives, it is well-grounded that linking two cyclodextrin moieties with a short linker group greatly enhances the molecular binding ability of the original cyclodextrin through the cooperative binding of one guest molecule in the closely located two cyclodextrin cavities.Therefore, this paper mainly studied the preparation of bridged β-cyclodextrin and its adsorption properties of thorium under differentconditions. The article mainly includes the following three sections:1. The research manily focuses on profiles of thorium,cyclodextrins, application ofβ-cyclodextrin derivatives, synthetic methodand application of bridged β-cyclodextrins. Last,the main research contents of this thesis was put forward.2.Mono-6-O-aminoethyl-β-cyclodextrin(6-EA-β-CD) is prepared by the reaction of β-cyclodextrin and 2-Chloroethylamine, and the means of FTIR, NMR were used to determine the reliability ofthe 6-EA-β-CD.We explored the adsorption behavior of 6-EA-β-CD on thorium,and the kinetics and thermodynamics of adsorption process.The results show that, chemically modified β-cyclodextrin has certain adsorption capacity, which laid a certain foundation for further explore the adsorption behavior of bridged β-cyclodextrins of thorium.3. Ethylamine-bridged β-cyclodextrins(EB β-CD) was synthetized using mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin and the 6-EA-β-CD with the mole ratio of 2:1 under certain conditions. The synthetic product(EB β-CD) was confirmed by FTIR, 1HNMR, elemental analysis.We further studied onthe adsorption behavior of EBβ-CD on thorium ions under different conditions.The adsorbent in this study had good adsorption quantity of Th(IV) at p H 4, and the adsorption equilibrium could reach a balance in 60 min. The adsorption quantity of Th(IV) was 10.49 mg g-1. The surface properties and pore structure of the EB β-CDwere investigated by SEM and BET nitrogen adsorption, indicating it is the typical mesoporous material, which was successfully used for the adsorption of Th(IV). Therefore, the bridged β-cyclodextrins will have a great application value in the reclamation of radioactive metals as an adsorbent material.Study on the adsorption kinetics and thermodynamics, results show that, the adsorption process of 6-EA-β-CD and EB β-CD on thorium were corresponded to the form of the pseudo-second-order kinetics equations and Langmuir adsorption isotherm. |
PDF Full Text Request