研究报告
王锐,许海娟,魏世勇,吴德勇.MOF-Fe吸附Se(Ⅳ)的特性与机制研究[J].环境科学学报,2018,38(8):3127-3137
MOF-Fe吸附Se(Ⅳ)的特性与机制研究
- The characteristics and mechanisms of selenite adsorption by MOF-Fe
- 基金项目：国家自然科学基金（No.41561053，21767009）
- 作者
- 单位
- 王锐
- 湖北民族学院化学与环境工程学院, 恩施 445000
- 许海娟
- 湖北民族学院化学与环境工程学院, 恩施 445000
- 魏世勇
- 湖北民族学院化学与环境工程学院, 恩施 445000
- 吴德勇
- 湖北民族学院化学与环境工程学院, 恩施 445000
- 摘要：水热法合成了MOF-Fe样品，研究了不同pH条件下MOF-Fe对亚硒酸根（Se（Ⅳ））的等温吸附和动力学吸附特性；基于吸附前后样品悬浮液的pH和Zeta电位、粉末样品的衰减漫反射红外光谱（ATR-IR）和X-射线光电子能谱（XPS），分析了MOF-Fe对Se（Ⅳ）的吸附机制.当吸附体系的初始pH分别为3.0、4.0和5.0时，样品对Se（Ⅳ）的Langmuir最大吸附容量（Qm）分别为0.690、0.534和0.538 mmol·g-1，3种pH条件下的吸附亲和力（b）表现为pH 3.0 > pH 4.0 > pH 5.0.3种pH条件下，样品对Se（Ⅳ）的吸附都在20 min内趋于饱和，二级动力学方程对吸附动力学数据的拟合度（R2）均大于0.999，MOF-Fe吸附Se（Ⅳ）的内扩散过程可用Weber-Morris方程描述.当吸附体系初始pH为3.0时，MOF-Fe与Se（Ⅳ）之间的吸附作用机制主要为：配位不饱和Fe与H2SeO3之间的配位作用、脱羟基后的活性Fe与[O2SeOH]-的键合作用及单齿羧羰基氧与Se（Ⅳ）之间的氢键作用.当吸附体系初始pH为5.0时，MOF-Fe与Se（Ⅳ）之间的吸附作用机制主要为：Fe—OH与[O2SeOH]-的阴离子交换作用，[SeO3]2-破坏了桥式羧羟基Fe—O键并与Fe—OH发生阴离子交换作用形成双齿吸附态Se（Ⅳ）以及单齿羧羰基氧与Se（Ⅳ）之间的氢键作用.
- Abstract：MOF-Fe was prepared under hydrothermal conditions, and the selenite (Se(Ⅳ)) adsorption behavior of MOF-Fe was investigated on adsorption isotherm and kinetics. Based on the changes of the pH and zeta potentials of the MOF-Fe particle suspensions and the results of the attenuation diffuse infrared spectrum (ATR-IR) and X-ray photoelectron spectroscopy (XPS) of the particles before and after the adsorption of Se(Ⅳ), the adsorption mechanism for Se(Ⅳ) by MOF-Fe were analyzed. At the initial pH of 3.0, 4.0 and 5.0, the Langmuir maximum adsorption capacities (Qm) for Se(Ⅳ) by MOF-Fe were 0.690, 0.534 and 0.538 mmol·g-1 respectively, and the adsorption affinities (b) show the order of pH 3.0 > pH 4.0 > pH 5.0. under three initial pH conditions, the adsorption of Se(Ⅳ) by MOF-Fe reached a saturation state after 20 min of the reaction time. The adsorption data were well fitted by using the pseudo-second-order kinetic model (R2>0.999), and the Weber-Morris model was suitable to describe the internal diffusion process of the absorption. At the initial pH 3.0, coordination between the unsaturated Fe atoms on the MOF-Fe surface and H2SeO3, bonding between the dehydroxylated Fe on the MOF-Fe surface and[O2SeOH]-, and hydrogen bond between the monodentate carbonyl O in carboxyls and Se(Ⅳ) were the main interaction mechanisms between Se(Ⅳ) and MOF-Fe. At the initial pH 5, the interaction mechanisms include anion ligand exchange between the Fe hydroxyls (Fe-OH) and[O2SeOH]-, bidentate coordination of Se(Ⅳ) due to[SeO3]2- interacting with the O-Fe bonds linked to the hydroxyls in carboxyl groups and the Fe-OH, and hydrogen bond between Se(Ⅳ) and the monodentate carbonyl O in carboxyls.
- Key words：MOFs adsorption selenite pH mechanisms
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