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采用共沉淀法制备了3种不同含铁量的氧化铁改性蛭石(Verm-Fex,x=5,10,20),研究了纯蛭石(Verm)和Verm-Fex的表面性质及吸附氟的特性。与样品Verm比较,3种Verm-Fex中Verm的d(002)层间距略有升高;Verm-Fex的孔体积、表面积、表面分形度均随含铁量的增加而升高,其中微孔体积和外表面积的增加幅度更明显。4种样品的等电点(IEP)也随含铁量的增加而明显升高;初始p H=5.0时,它们的表面ζ电位分别为-16.4,-6.1,10.5和28.4 m V。4种样品对氟的等温吸附数据用单吸附位Langmuir模型拟合(R2=0.973~0.995)时,Verm的R2最高;双吸附位Langmuir模型可很好地描述3种Verm-Fex样品的等温吸附过程(R2=0.991~0.998);Freundlich模型对4种样品吸附数据的拟合度较差(R2=0.835~0.937),但R2随样品含铁量的增加而略微升高。初始p H=5.0时,Verm和Verm-Fex(x=5,10,20)对氟的最大吸附容量(qmax)分别为3.18,6.76,9.27和12.43 mg·g-1。可见,Verm-Fex(尤其含铁量较高的产物)对表生环境中氟的吸附固定性能明显高于Verm。
Three kinds of iron oxide modified vermiculite with different iron content (Verm-Fex, x = 5,10,20) were prepared by co-precipitation method. The surface properties and adsorption of pure Vermiculite and Verm-Fex Fluorine characteristics. Compared with the sample Verm, the d (002) layer spacing of Verm in three kinds of Verm-Fex slightly increased. The pore volume, surface area and surface fractal of Verm-Fex increased with the increase of iron content, The increase of volume and surface area is more obvious. The isoelectric point (IEP) of four samples also increased with the increase of iron content. Their surface zeta potentials were -16.4, -6.1, 10.5 and 28.4 mV at initial p H = 5.0. The isotherm data of four samples were fitted with the Langmuir model of single adsorption site (R2 = 0.973-0.995), and the R2 of Verm was the highest. The double adsorption Langmuir model could describe the isothermal adsorption of three samples of Verm-Fex well (R2 = 0.991 ~ 0.998). The fitting results of Freundlich model for the adsorption data of the four samples were poor (R2 = 0.835-0.937), but R2 slightly increased with the increase of iron content in the samples. The maximum adsorption capacity (qmax) of Verm and Verm-Fex (x = 5, 10, 20) for fluorine at the initial p H = 5.0 was 3.18, 6.76, 9.27 and 12.43 mg · g -1, respectively. Visible, Verm-Fex (especially high iron content) on the surface of fluoride adsorption and fixation was significantly higher than Verm.