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国家自然科学基金(20907055)

作品数:5 被引量:20H指数:4
相关作者:盛国栋王祥科更多>>
相关机构:中国科学院等离子体物理研究所更多>>
发文基金:国家自然科学基金国家重点基础研究发展计划中国科学院知识创新工程更多>>
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Adsorption of Eu(Ⅲ) on titanate nanotubes studied by a combination of batch and EXAFS technique被引量:8
2012年
The effects of pH,contact time and natural organic ligands on radionuclide Eu(Ⅲ) adsorption and mechanism on titanate nanotubes(TNTs) are studied by a combination of batch and extended X-ray absorption fine structure(EXAFS) techniques.Macroscopic measurements show that the adsorption is ionic strength dependent at pH < 6.0,but ionic strength independent at pH > 6.0.The presence of humic acid(HA) /fulvic acid(FA) increases Eu(Ⅲ) adsorption on TNTs at low pH,but reduces Eu(Ⅲ) adsorption at high pH.The results of EXAFS analysis indicate that Eu(Ⅲ) adsorption on TNTs is dominated by outer-sphere surface complexation at pH < 6.0,whereas by inner-sphere surface complexation at pH > 6.0.At pH < 6.0,Eu(Ⅲ) consists of ~ 9 O atoms at REu?O ≈ 2.40 in the first coordination sphere,and a decrease in NEu-O with increasing pH indicates the introduction of more asymmetry in the first sphere of adsorbed Eu(Ⅲ).At long contact time or high pH values,the Eu(Ⅲ) consists of ~2 Eu at REu-Eu ≈ 3.60 and ~ 1 Ti at REu-Ti ≈ 4.40 ,indicating the formation of inner-sphere surface complexation,surface precipitation or surface polymers.Surface adsorbed HA/FA on TNTs modifies the species of adsorbed Eu(Ⅲ) as well as the local atomic structures of adsorbed Eu(Ⅲ) on HA/FA-TNT hybrids.Adsorbed Eu(Ⅲ) on HA/FA-TNT hybrids forms both ligand-bridging ternary surface complexes(Eu-HA/FA-TNTs) as well as surface complexes in which Eu(Ⅲ) remains directly bound to TNT surface hydroxyl groups(i.e.,binary Eu-TNTs or Eu-bridging ternary surface complexes(HA/FA-Eu-TNTs)).The findings in this work are important to describe Eu(Ⅲ) interaction with nanomaterials at molecular level and will help to improve the understanding of Eu(Ⅲ) physicochemical behavior in the natural environment.
SHENG GuoDongYANG ShiTongZHAO DongLinSHENG JiangWANG XiangKe
Investigation of radionuclide ^(60)Co(Ⅱ) binding to TiO_2 by batch technique,surface complexation model and DFT calculations被引量:4
2012年
The interaction between radionuclides and solid/water interfaces is important to understand the physicochemical processes of radionuclides in the natural environment.Herein,the interaction of 60Co(Ⅱ) with TiO 2 in aqueous solution as a function of pH and ionic strength was studied by using batch technique combined with surface complexation model and density functional theory(DFT) calculations.The batch experimental results showed that the adsorption of 60Co(Ⅱ) was dependent on pH and independent of ionic strength,indicating the formation of inner-sphere surface complexes on TiO 2 surfaces.The results of surface complexation models and DFT calculations indicated that the surface species of 60Co(Ⅱ) adsorbed on TiO 2 followed the trend:B structure(i.e.,60Co(Ⅱ) was linked to one bridge oxygen site) was the dominant surface species at low pH,and TT structure(i.e.,60Co(Ⅱ) was linked to two terminal oxygen sites) became the important surface complex at neutral and alkaline pH values.These results demonstrated that a multi-technique approach could lead to definitive information on the structures of adsorbed 60Co(Ⅱ) at the molecular level at the TiO 2 /water interfaces,as well as realistic models to rationalize and accurately evaluate the macroscopic manifestations of radionuclide adsorption phenomena.
REN XueMeiYANG ShiTongTAN XiaoLiCHEN ChangLunWANG XiangKe
关键词:TIO2INTERACTION
静态法和EXAFS技术研究放射性核素63^Ni(Ⅱ)在丝光沸石上的吸附机理被引量:4
2012年
结合静态实验和X射线吸收精细结构光谱(EXAFS)技术研究了接触时间、离子强度、初始浓度以及共存电解质离子等水化学条件对放射性核素63Ni(II)在丝光沸石上的吸附行为和微观机制的影响.宏观实验结果表明:放射性核素63Ni(II)在丝光沸石上的吸附在pH<7的范围内受离子强度影响,而在pH>7的范围内不受离子强度影响.放射性核素63Ni(II)在丝光沸石上的吸附率随着固体浓度的增加而升高,而对应的吸附量却随着固体浓度的增加而降低.溶液中共存的电解质离子对63Ni(II)在丝光沸石上的吸附有一定的促进或抑制作用,具体的影响趋势和程度由共存离子的性质、共存离子与63Ni(II)的络合能力以及与丝光沸石表面的亲和力大小共同决定.EXAFS微观结构分析结果表明:在pH6.5的溶液中,63Ni(II)与丝光沸石结构框架中的Na+/Ca2+等阳离子进行离子交换,形成六水合的外层络合物,不同离子强度下63Ni(II)的微观形态没有明显区别.63Ni(II)在丝光沸石上的吸附随时间的变化呈现两种不同的作用机制:在溶液pH7.2的条件下,吸附初始的快速反应阶段中63Ni(II)的吸附主要以通过形成内层络合物的形式进行;随着接触时间的增长,63Ni(II)在丝光沸石上的吸附机理转变为镍页硅酸盐共沉淀或者氢氧化镍沉淀的形成.初始63Ni(II)浓度为100mg/L的EXAFS图谱分析结果表明表面多聚体的形成是此条件下63Ni(II)在丝光沸石上的主要吸附机理.放射性核素63Ni(II)在丝光沸石/水界面的吸附行为和形态分布对于准确预测其在环境介质中的迁移转化和生物有效性等物理化学行为具有重要的意义.
杨世通盛国栋郭志强谭小丽徐进章王祥科
关键词:丝光沸石
Investigation of radionuclide~(63)Ni(Ⅱ) sequestration mechanisms on mordenite by batch and EXAFS spectroscopy study被引量:5
2012年
The sorption behavior and microscopic sequestration mechanisms of radionuclide 63Ni(II) on mordenite as a function of aging time, ionic srength, initial 63Ni(II) concentrations, solid content and coexistent electrolyte ions were investigated by the combination of batch and EXAFS techniques. Macroscopic experiment results show that the sorption of 63Ni(II) is dependent on ionic strength at pH〈7, and independent of ionic strength at pH〉7. The sorption percentage of 63Ni(II) on mordenite increases with increasing solid content, while the sorption capacity decreases as solid content increases. The presence of different electrolyte ions can enhance or inhibit the sorption of Ni(II) on mordenite in various degrees. EXAFS analysis results of the sam- ples under three different ionic strengths suggest that the retained 63Ni(II) in these samples exists in an octahedral environment with six water ligands. In the initial period of rapid uptake, the sorption of 63Ni(II) is dominated by the formation of innersphere surface complexes. As aging time increases, 63Ni(II) sequestration behavior tends to be mainly controlled by the formation of Ni phyllosilicate coprecipitates and/or Ni(OH)2(s) precipitates. Results for the second shell fit of the sample prepared at an initial 63Ni(II) concentration of 100 mg/L indicate the possible formation of Ni polynuclear surface complexes. Both the macroscopic sorption data and the molecular level evidence of 63Ni(II) surface speciation at the mordenite/water interfaces should be factored into better predictions of the mobility and bioavailability of 63Ni(II) in environment mediums.
YANG ShiTong,SHENG GuoDong,GUO ZhiQiang,TAN XiaoLi,XU JinZhang & WANG XiangKe Key Laboratory of Novel Thin Film Solar Cells,Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,China
静态法和EXAFS技术研究Eu(III)在钛酸纳米管上的吸附行为和微观机制被引量:5
2012年
结合静态实验和X射线吸收精细结构谱学(EXAFS)技术研究了pH、时间、有机配体等环境因素对放射性核素Eu(III)在钛酸纳米管上的吸附行为和微观机制的影响.宏观实验结果表明:Eu(III)在钛酸纳米管上的吸附在pH<6.0条件下受离子强度影响,而在pH>6.0条件下不受离子强度影响;腐殖酸HA/FA在低pH条件下可以促进Eu(III)在钛酸纳米管上的吸附,而在高pH条件下抑制Eu(III)在钛酸纳米管上的吸附.EXAFS微观分析结果表明:在pH<6.0条件下,吸附属于外层吸附机理;在pH>6.0条件下,吸附属于内层吸附机理.pH<6.0时,中心原子Eu周围只有Eu-O一个配位层,其平均键长为2.40,配位数在9左右;随着pH逐渐升高,第一配位层的配位数下降,表明吸附Eu原子配位的对称性下降.当吸附时间延长或pH升高,吸附原子Eu周围出现了Eu-Eu和Eu-Ti第二配位层,其平均键长分别为3.60和4.40,配位数分别在2或1左右,表明形成了内层吸附产物或表面沉淀或表面多聚体.腐殖酸HA/FA的存在,可以改变Eu(III)在钛酸纳米管表面的吸附形态和微观原子结构,Eu(III)不仅可以与钛酸纳米管的表面羟基直接键合形成二元表面复合物(Eu-TNTs),还可以通过HA/FA的桥连作用形成三元表面复合物(HA/FA-Eu-TNTs).这些研究结果对于评估放射性核素Eu(III)与纳米材料在分子水平上的作用机理及分析Eu(III)在环境中的物理化学行为具有重要的意义.
盛国栋杨世通赵东林盛江王祥科
关键词:钛酸纳米管胡敏酸
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