Synthesis And Characterization Of 2,6-bis(5,6-dinonyl-1,2,4-triazine-3-yl) Pyridine And Its Fundamental Properties

The long-lived minor actinide (MA(III)) elements contained in high level liquid waste (HLLW) generated in reprocessing process of nuclear spent fuel have long-term radiological risk, it is valuable to separate them from HLLW for further transmutation.2,6-bis(5,6-dialkyl-1,2,4-triazine-3-yl)pyridine (R-BTP) is a kind of multidentate chelating agent containing nitrogen which has better complexing ability for MA(III) than Ln(III). A novel soft ligand 2,6-bis(5,6-dinonyl-1,2,4-triazine-3-yl) pyridine (Non-BTP) was synthesized using 2,6-pyridinedicarbonitrile and ethyl decanoate as raw materials. It was characterized by FT-IR, TG-DSC, ESI-MS, and 1H NMR. An improved synthetic process of 2,6-pyridinedicarboxamide dihydrazone was proposed. The optimum conditions were described as follows:2,6-pyridine dicarbonitrile: 85%N2H4=1:15, reaction time=30 h, reaction temperature=30℃. The optimum yield of the product was 85.37%.Using 30% n-octanol/70% n-dodecane as diluent, the extraction behavior of Rb(Ⅰ), Cs(Ⅰ), Sr(Ⅱ), Ba(Ⅱ), Pd(Ⅱ), Ru(Ⅲ), La(Ⅲ), Co(Ⅲ), Fe(Ⅲ), Ni(Ⅲ), Y(Ⅲ), Sm(Ⅲ), Yb(Ⅲ), Zr(Ⅳ) and Mo(Ⅳ) from HNO3 solution was studied. The influences of HNO3 concentration, Non-BTP content, contact time, and temperature on the extraction ability were investigated. It was found that the complex composition between Pd(Ⅱ) and Non-BTP was determined as 1:2 type. In addition, the thermodynamic parameters of Pd(Ⅱ) extrated by Non-BTP were calculated.A novel macroporous silica-based 2,6-bis(5,6-dinonyl-1,2,4-triazine-3-yl) pyridine (Non-BTP/SiO2-P) was prepared through impregnation and immobilization of the corresponding R-BTP compound into the pores of the macroporous SiO-P support. The appearance, chemical composition, and inner structure were characterized by FT-IR, SEM, TG-DSC, XRD, and BET.The effects of HNO3 concentration and contant time on the adsorption of Rb(Ⅰ), Cs(Ⅰ), Sr(Ⅱ), Ba(Ⅱ), Pd(Ⅱ), Ru(Ⅲ), La(Ⅲ), Co(Ⅲ), Fe(Ⅲ), Ni(Ⅲ), Y(Ⅲ), Sm(Ⅲ), Yb(Ⅲ), Zr(Ⅳ), Mo(Ⅵ), and more than 10 typical elements onto the Non-BTP/SiO2-P materials were investigated at 25℃. The Non-BTP/SiO2-P material showed excellent adsorption ability and selectivity for Pd(Ⅱ) over all of the other tested metals. The optium acidity for the Pd(Ⅱ) adsorption was 3.0 M HNO3. In addition, the uptake of Ln(Ⅲ) onto the Non-BTP/SiO2-P material was negligible, which was beneficial to separate MA(Ⅲ) from Ln(Ⅲ) using this composite in further researches.