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用密度泛函理论(densityfunctiontheory,DFT)和X射线近边结构(X-rayabsorptionnearedgestructure,XANES)模拟计算了不同酸度(pH=7.0,7.5和8.0)下Zn(II)在水锰矿表面的吸附.优化的几何结构表明,只有双边吸附方式的水解簇既能解释H+释放机制,又能与扩展X射线吸收精细结构(extendedX-rayabsorptionfinestructure,EXAFS)实验键长值相吻合.吸附能计算表明,各种吸附方式的稳定性双边(DE)>双角(DC)>B型单边(SE-B)>A型单边(SE-A);水解能计算表明各种吸附态Zn2+均比溶液中水合锌离子易水解.各种吸附簇模型的XANES计算谱未能与实验谱吻合,即,表面发生的并不是简单的吸附.pH=7.5和pH=8.0吸附样品的XANES实验谱与Zn5(OH)6(CO3)2的实验谱非常接近,因此认为pH=7.5和pH=8.0下Zn(II)在水锰矿表面发生沉淀,Zn(II)是Zn—O八面体和Zn—O四面体的混合,它们按类似Zn5(OH)6(CO3)2结构中的八面体和四面体排列方式排列.pH=7.0时,Zn(II)在水锰矿表面发生的主要是边连接方式的吸附.
The adsorption of Zn (II) on the manganite surface at different acidity (pH = 7.0, 7.5 and 8.0) was simulated by density functional theory (DFT) and X-ray absorption structure structure (XANES) The results show that only the hydrolysis cluster of the bilateral adsorption method can explain both the H + release mechanism and the extended bond length of the extended X-ray absorption absorption structure (EXAFS), and the adsorption energy calculations show that various adsorption (DE)> double> (DC)> SE-B> SE-A; Hydrolytic energy calculations showed that the adsorption capacity of Zn2 + was higher than that of hydrated zinc Ions easily hydrolyzed.The XANES calculated spectra of various adsorption cluster models did not fit the experimental spectra, that is, the surface was not simply adsorbed.XHES experimental spectrum of adsorbed samples with pH = 7.5 and pH = 8.0 and Zn5 (OH) 6 (CO3) 2. Therefore, it is considered that Zn (II) precipitates on the surface of the manganite at pH = 7.5 and pH = 8.0. Zn (II) is a mixture of Zn-O octahedron and Zn- They are arranged in an octahedral and tetrahedral arrangement similar to the structure of Zn5 (OH) 6 (CO3) 2. When pH = 7.0, Zn (II) Surface adsorption occurs primarily edge connection.