Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084, PR China.
Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084, PR China; Beijing Key Laboratory of Radioactive Waste Treatment, Tsinghua University, Beijing 100084, PR China.
J Hazard Mater. 2016 Jan 15;301:286-96. doi: 10.1016/j.jhazmat.2015.09.004. Epub 2015 Sep 3.
Nanoscale zero valent iron (ZVI)/graphene (GF) composite was prepared and characterized by Brunauer-Emmett-Teller (BET) surface area measurement and zeta potential determination. The adsorption isotherm of Co(II) in aqueous solution, as well as the influence of pH values and ionic strengths was studied. The mechanism of Co(II) adsorption by GF was investigated through analyzing the sorption products at initial pH of 3.0, 6.0 and 9.0 using high-resolution transmission electron microscope with energy dispersive X-ray detector (HRTEM-EDX), X-ray diffraction (XRD), vibrating-sample magnetometer (VSM), Raman spectra, X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) measurement. The results indicated that Langmuir isotherm model fitted well and the adsorption capacity was 131.58 mg g(-1) at 30°C. Adsorption capacity was not significantly influenced by ionic strength and kept high at pH 4.0∼9.0. The detail information of GF-Co interaction at different initial pH values was obtained using XAFS analysis combined with other characterization methods. Coordination numbers (CN) and interatomic distances (R) of both Fe and Co were given. At pH 3.0 and pH 6.0, the Co-substituted iron oxides transformed to CoFe2O4-like structure, while at pH 9.0 they changed to green rust-like phases. Co occupied preferentially in the octahedral sites in acid solution. The adsorption mechanism of Co(II) was attributed to inner-sphere complexation and dissolution/re-precipitation of the substituted metal oxides.
纳米零价铁（ZVI）/石墨烯（GF）复合材料通过比表面积测量和动电电位测定进行了制备和表征。研究了水溶液中 Co(II)的吸附等温线以及 pH 值和离子强度的影响。通过在初始 pH 值为 3.0、6.0 和 9.0 时分析吸附产物，利用高分辨率透射电子显微镜与能量色散 X 射线探测器（HRTEM-EDX）、X 射线衍射（XRD）、振动样品磁强计（VSM）、拉曼光谱、X 射线光电子能谱（XPS）和 X 射线吸收精细结构（XAFS）测量，研究了 GF 对 Co(II)的吸附机理。结果表明，Langmuir 等温线模型拟合良好，在 30°C 时吸附容量为 131.58mg/g。离子强度对吸附容量影响不大，在 pH 4.0∼9.0 时保持较高水平。通过 XAFS 分析结合其他表征方法，获得了不同初始 pH 值下 GF-Co 相互作用的详细信息。给出了 Fe 和 Co 的配位数（CN）和原子间距离（R）。在 pH 3.0 和 pH 6.0 时，Co 取代的铁氧化物转化为 CoFe2O4 样结构，而在 pH 9.0 时它们转变为绿锈样相。Co 在酸性溶液中优先占据八面体位置。Co(II)的吸附机理归因于内球络合和取代金属氧化物的溶解/再沉淀。
