吡啶基改性纤维状介孔二氧化硅微球的辐射制备及其对U(VI)的吸附性能

摘要

首先合成了双键改性的纤维状介孔二氧化硅纳米微球(F-SiO2-K),将其分散在4-乙烯基吡啶(4-vinylpyridine,4-VP)或4-VP的甲醇溶液中,通过共辐射接枝的方法,制备了吡啶基改性纤维状介孔SiO2纳米微球(F-SiO2-VP).热重分析结果表明,聚4-乙烯基吡啶(P(4-VP))在F-SiO2微球上的接枝率随4-VP单体浓度和吸收剂量增加而增加,但随剂量率的增加先增大后减小.将F-SiO2-VP微球分散在含有U(VI)的硝酸溶液中,测定了室温下微球对U(VI)的吸附容量,并对吸附动力学和吸附等温线进行了分析.结果表明,F-SiO2-VP微球对U(VI)的吸附容量与硝酸浓度和P(4-VP)的接枝率有关.当硝酸浓度为5 mol/L,P(4-VP)的接枝率为16%时,对U(VI)的吸附容量最大,达到163 mg/g.该吸附过程符合准二级动力学模型,其吸附热力学则当U(VI)浓度低时符合Freundlich模型,而U(VI)浓度高时符合Langmuir等温吸附模型.%In this paper, double-bond-modified fibrous mesoporous silica (F-SiO2-K) microspheres were prepared first, and then grafted with poly (4-vinylpyridine) (P(4-VP)) in 4-VP or its methanol solution initiated by γ-ray irradiation to obtain pyridine modified mesoporous silica (F-SiO2-VP) microspheres. The Fourier transform infrared spectroscopy (FTIR) andthermal gravimetric analysis(TGA) results indicated the successful grafting of P(4-VP). The degree of grafting (DG) of P(4-VP), which was calculated from TGA curves, increased with the monomer concentration and the absorbed dose,however reached a maximum value at a moderate dose rate. The adsorption ability of F-SiO2-VP for U(VI) in nitric acid solution was investigated. The results show that the adsorption capacity is related to the concentration of nitric acid and the DG of F-SiO2-VP, and reaches a maximum of 163 mg/g. The adsorption kinetics fits the pseudo-second-order model, and the adsorption isotherm of F-SiO2-VP fits the Freundlich model at low U(VI) concentrations and the Langmuir isotherm well at high U(VI) concentrations.