负载型纳米钛酸锶钡对水中Cd<sup>2+</sup>吸附行为研究

采用络合溶胶-凝胶法制备了钛酸锶钡溶胶,将其浸渍在硅胶G上,经高温煅烧后,制得固载于硅胶G上的纳米钛酸锶钡,以X射线衍射(XRD)、扫描电镜(SEM)和傅里叶变换红外光谱(FTIR)进行了表征。以火焰原子吸收为检测手段,系统地研究了负载型纳米钛酸锶钡对水中Cd²⁺的吸附行为。结果表明,纳米钛酸锶钡能够牢固地负载于硅胶G表面。当介质的pH值为4-7时,该吸附剂对水中的Cd²⁺具有很强的吸附能力,其吸附行为符合Freundlich吸附等温模型和HO准二级动力学方程式,并分别计算了吸附过程的焓变(ΔΗ),自由能变(ΔG)和熵变(ΔS)等热力学参数,表明该吸附过程是自发的吸热物理过程。被吸附的Cd²⁺可用1mol·L^-1的硝酸完全洗脱回收。将其应用于水中痕量Cd²⁺的吸附,建立了负载型纳米钛酸锶钡吸附富集,火焰原子吸收法测定水中痕量Cd²⁺的新方法。用于自来水和地表水中镉的测定,结果满意。

Abstract

Nanometer barium-strontium titanate immobilized on silica gel G was successfully prepared by the citrate acid sol-gel method and characterized using X-ray diffraction (XRD),scanning electron microscope (SEM) and Fourier transform infrared spectrophotometer (FTIR).By means of the determination of flame atomic absorption spectrometry(FAAS),the adsorption behavior of immobilized nanometer-barium strontium titanate for cadmium ion was investigated.The results showed that the nanometer barium-strontium titanate was immobilized on the silica gel G firmly,gaining a new sort of adsorbent.And the cadmium ion studied could be quantitatively retained in the pH value range of 4-7.The adsorption behavior followed a Freundlich adsorption isotherm and a pseudo-second-order kinetic model.The thermodynamic constants of the adsorption process,such as enthalpy changes(ΔH),Gibbs free energy changes(ΔG) and entropy changes(ΔS),were evaluated.These showed that the adsorption of cadmium ion by immobilized nanometer barium-strontium titanate was endothermic and spontaneous physical process.The cadmium ion adsorbed could be completely eluted using 1 mol·L-1 HNO3.A new method for the determination of trace cadmium ion in water based on this immobilized nanometer barium-strontium titanate preconcentration and FAAS determination was proposed.The method has been applied to the determination of trace cadmium ion in tap water and river water with satisfactory results.

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张东, 张文杰, 关欣, 高虹, 何红波. 负载型纳米钛酸锶钡对水中Cd²⁺吸附行为研究[J]. 光谱学与光谱分析, 2009, 29(3): 824. ZHANG Dong, ZHANG Wen-jie, GUAN Xin, GAO Hong, HE Hong-bo. Adsorption Behavior of Immobilized Nanometer Barium-Strontium Titanate for Cadmium Ion in Water[J]. Spectroscopy and Spectral Analysis, 2009, 29(3): 824.

负载型纳米钛酸锶钡对水中Cd²⁺吸附行为研究

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