Preparation Of A Few Novel Macroporous Silica-based Soft-ligand Materials And Their Adsorption Properties For Metals

2,6-(5,6-dialkyl-1,2,4-triazine-3-yl)-pyridine (R-BTP) is a kind of multidentate chelating agent of soft-ligand containing nitrogen. It seems to have better complexing ability for minor actinides (MAs). To separate MA from highly active liquid waste (HLW), four derivatives of R-BTP,2,6-bis(5,6-dimethyl-1,2,4-triazine-3-yl) pyridine (Me-BTP),2,6-bis(5,6-dipropyl-1,2,4-triazine-3-yl)pyridine (Pro-BTP),2,6-bis(5,6-dipentyl-1,2,4-triazine-3-yl)pyridine (Pen-BTP), and 2,6-bis(5,6-diheptyl-1,2,4-triazine-3-yl)pyridine (Hep-BTP) were synthesized using 2,6-pyridinedicarbonitrile and ester as raw materials. They were characterized by elementary analysis, FT-IR, TG-DSC, FT-IR, ESI-MS, and 1H NMR.The synthesis procedure of immediate hexylacyloin was optimized. The optimum conditions were described as follows:molar ratio of Na, C2H5OC2H5, and n-C5H11COOC2H5 was 2:1:6 under protection by nitrogen gas at 25℃. The yield of hexylacyloin was 71.54%.Three novel macroporous silica-based soft ligand materials Me-BTP/SiO2-P, Pro-BTP/SiO2-P, and Pen-BTP/SiO2-P were synthesized by impregnation and immobilization of Me-BTP, Pro-BTP, and Pen-BTP molecules into the pores of SiO2-P, respectively. All the R-BTP/SiO2-P materials were characterized by FT-IR, TG-DSC, SEM, XRD, and BET.The effects of the HNO3 concentration in the range of 0.4-5.0 M HNO3 and contact time on the adsorption of some typical elements such as Na(Ⅰ), K(Ⅰ), Rb(Ⅰ), Cs(Ⅰ), Sr(Ⅱ), Ba(Ⅱ), Pd(Ⅱ), Ru(Ⅲ), Mo(Ⅵ), Zr(Ⅵ), Fe(Ⅲ), Co(Ⅱ), Ni(Ⅱ), La(Ⅲ), Sm(Ⅲ), Yb(Ⅲ), and Y(Ⅲ) onto Me-BTP/SiO2-P, Pro-BTP/SiO2-P, and Pen-BTP/SiO2-P were investigated at 25℃. The results showed that the macroporous silica-based soft ligand materials exhibited adsorption for Pd(Ⅱ), Fe(Ⅲ), Co(Ⅱ), and/or Ni(Ⅱ). The adsorption of Pen-BTP/SiO2-P for Pd(Ⅱ) was strong with the distribution coefficient of more than 1000 cm3/g. La(Ⅲ), Sm(Ⅲ), Yb(Ⅲ), and Y(Ⅲ) as the representative of rare earths REs(Ⅲ) showed weak or almost no adsorption onto R-BTP/SiO2-P, indicative of no adsorption for all REs(Ⅲ) because of lanthanide contraction. It is beneficial to effective separation An(Ⅲ)/RE(Ⅲ) from HLLW.