Preparation Of Silica-based Triazine Derivative Impregnated Material And Its Basic Adsorption Property

The partitioning of the long-lived minor actinides(MA)and other long-lived fission products(LLFP)contained in highly active liquid waste(HLW)is one of the most challenging works that have not been solved for decades.To reduce the potential risk and harmfulness caused by those long-lived radionuclides in HLW to environment and public health,the partitioning&transmutation(P&T)strategy for effective treatment of MA and LLFP and has been proposed.MA and LLFP are required to separate from HLW and then transmutated into short-lived or stable nuclides.To achieve this purpose,a new partitioning conceptual process entitled MPS(MA and Pd Separation by Extraction Chromatography)for direct removal of MA and Pd from HLW has been proposed.It is known that one class of N-containing bis-triazine derivatives have excellent extraction ability and selectivity for MA(?).However,the investigations on the complexation of Pd(?)with the N-containing bis-triazine derivatives have not been understood.The composition and structure of the complex of Pd(?)with these soft-ligands have not been reported.In the present work,12 bis-triazine soft-ligand derivatives and their novel silica-based bis-triazine derivatives functional materials were synthesized and characterized.The complexation of Pd(?)with these soft-ligand derivatives through the density functional theory(DFT)calculation were investigated.The main research results were listed as follows:(1)12 typical bis-triazine soft-ligand derivatives with different structures were synthesized by multi-step reaction,and 9 of them were prepared for the first time.The composition and structures of these soft-ligands were characterized by element analysis?13C NMR?1N MR?FT-IR?SEM?ESI-MS and powder XRD.(2)The single-crystal structures of twelve soft-ligands and two novel complexes of palladium were identified by X-ray diffraction for the first time.The intermolecular and intramolecular interaction of bis-triazine derivatives through hydrogen bonding between water and nitrogen was found.The composition,structure,and complexation behavior of the complex of Pd(?)with two typical bis-triazine derivatives were reported for the first time.It was performed by 1HNMR titrations,isothermal titration calorimetry(ITC)and quantum chemistry calculation based on the density functional theory(DFT).A new research field,the coordination chemistry of Pd(?),one of the precious metals,has been opened.(3)The solvent extraction of Pd(?)and about 20 typical metals such as alkali metals Li(?),Na(?),K(?),Rb(?)and Cs(?),alkaline earth metals Mg(?),Ca(?),Sr(?)and Ba(?),and rare earths La(?),Nd(?),Yb(?)and Y(?),and others Fe(?),Co(?),Ni(?),Ru(?),Zr(?)and Mo(?)with the bis-triazine soft-ligand derivatives were investigated.The effects of HNO3 concentration,contact time and temperature on the extraction of these typical metals with 12 soft-ligands in n-octanol/HNO3 medium were studied.These ligands showed strong extraction ability and high selectivity towards Pd(?)over all others.The extraction mechanism of Pd(?)was elucidated based on the ESI-MS spectra and Pd(?)coordination behavior investigations.By comparing the differences in the extraction abilities of ligands towards Pd(?)and combining the single crystal structures of the triazine derivatives,the relationship between the structure and extraction performance of the ligands was established.The formation of both 1:1 and 2:1 complexes of R-BTP with Pd(?)were firstly found.The 2:1 species of Pd(?)were unusual paramagnetic distorted six-coordinate compounds.RBTBP ligands had two ? and OO model conformations in their single crystal structures.The ligand with ? conformation could form to two species,a monouclear 1:1 and a binuclear 1:2 types of the Pd(?)complexes,while the ligands with 00 conformation type could only form to a 1:1 species with Pd(?).It is firstly demonstrated that the symmetrical ligands,CA-MP and CA-BOPhen with two opened triazine rings,had strongly selective complexation ability and extremely fast extraction rates towards Pd(?)over other 19 typical metals in HNO3 media.(5)Twelve novel macroporous silica-triazine derivatives functional materials were prepared by vacuum impregnating and immobilizating corresponding triazine derivative into the pores of macroporous SiO2-P carrier.SEM,N2 adsorption-desorption isotherms,29Si solid state NMR,powder XRD,FT-IR,TG-DSC,EDS and XPS were performed to characterize the structure and chemical composition of the materials,and the combination mechanism between the ligand and the SiO2-P carrier was confirmed.(6)The effects of some factors such as HNO3 concentration,contact time and temperature on the distribution coefficients(Kd)values of 20 typical metals in HNO3 media towards these functional materials were studied.The adsorption kinetics and thermodynamic properties as well as the maximum adsorption capacity of Pd(?)towards these adsorbents were determined.It has been firstly found that two novel materials,CA-MP/SiO2-P and CA-BOPhen/SiO2-P,had extremely fast adsorption rate and highly selective adsorption ability towards Pd(?)over other 19 typical metals.The materials containing the symmetrical R-BTBP ligands had strong adsorption ability for Pd(?),Co(?),Ni(?),Zr(?)and Mo(?),while those containing asymmetrical ligands had strong adsorption ability only for Pd(?),Co(?)and Ni(?).The relationships between the adsorption kinetics of Pd(?)by typical materials and the structure of Pd(?)complexes were investigated.The adsorption mechanism of palladium was clarified.Based on the strong adsorption ability and high selectivity of Pd(?),the application of novel macroporous silica-triazine derivatives functional materials in Pd(?)separation along with MA(?)from HLW under the formwork of MSP process is promising.This is beneficial to the realization of the P&T strategy.On the other hand,a new research field,the coordination chemistry of palladium with multidentate N-containing triazine derivatives,has been opened up.