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化学学报
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化学学报 ›› 2010, Vol. 68 ›› Issue (16): 1641-1648. 上一篇    下一篇

研究论文

基于秸秆模板法制备多孔纳米钛酸锶钡及其对重金属的吸附性能

张东*，王敏，谭玉玲   

  1. (沈阳理工大学环境与化学工程学院 沈阳 110159)
  • 投稿日期:2009-08-19 修回日期:2009-10-22 发布日期:2010-04-01
  • 通讯作者: 张东 E-mail:sylgdxdong@sina.com

Preparation of Porous Nano-barium-strontium Titanate by Sorghum Straw Template Method and Its Adsorption Capability for Heavy Metal Ions

ZHANG Dong, WANG Min, TAN Yu-Ling   

  1. (School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110159)
  • Received:2009-08-19 Revised:2009-10-22 Published:2010-04-01

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被引次数

34 | 1

以高粱秸秆为模板, 采用溶胶-凝胶法制备了纳米钛酸锶钡多孔吸附剂(SPBST), 以X射线衍射(XRD)、扫描电子显微镜(SEM)和傅立叶变换红外光谱(FTIR)进行表征. 考察了该多孔吸附剂对水中重金属铅、镉和锌的吸附富集性能, 探讨了煅烧温度对吸附剂形貌和吸附性能的影响. 并以镉离子为例, 系统地研究了吸附热力学和动力学. 结果表明, 各煅烧温度下合成的多孔材料均由钙钛矿结构的纳米钛酸锶钡组成, 晶体粒径均不大于20 nm, 多孔吸附剂对水中铅、镉和锌均有较强的吸附能力, 吸附性能与材料的煅烧合成温度和介质的pH值以及吸附时间有关. 煅烧温度过高, 纳米钛酸锶钡晶体团聚严重, 吸附能力降低; 温度过低, 材料松散易碎, 不利于重复使用, 750 ℃煅烧6 h合成的材料性能最好. 当介质的pH值为5～8时, 吸附70 min, 对铅、镉和锌的静态吸附容量分别为191.51, 19.00和19.97 mg• g―1. 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, 吸附过程焓变(ΔH)为35.905 kJ•mol－1, 各温度下的自由能变(ΔG)均小于零, 熵变(ΔS)均为正值, 吸附过程的活化能(Ea)为62.430 kJ•mol－1. 该吸附过程是自发的吸热物理过程. 被吸附的金属离子均可用1 mol•L－1的硝酸完全洗脱回收. 对铅、镉和锌的富集因子均超过200. 将其应用于水中痕量铅、镉和锌的吸附富集和原子吸收测定, 回收率分别为90.3%～103.4%, 91.5%～103.2%和94.35%～101.1%.

关键词: 多孔纳米钛酸锶钡, 高粱秸秆, 生物模板法, 吸附行为, 重金属, 火焰原子吸收光谱法

Using sorghum straw as template, porous nano-barium-strontium titanate (SPBST) was successfully prepared by the sol-gel method, and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and fourier transform infrared spectrophotometry (FTIR). Its adsorption capabilities for heavy metal such as lead ion, cadmium ion and zinc ion were studied. The effects of the calcining temperature on the structure of porous adsorbent and its adsorbing capacity were discussed. Moreover, taking the cadmium ion as an example, the thermodynamics and kinetics of the adsorption were completely investigated. The results showed that the sorbents were porous, buildup perovskite nano-barium-strontium titanate, and the average particle diameters of crystalloid were not more than 20 nm. The crystalloids of the sorbent became agglomerated when the calcining temperature was too high, which was infaust for the adsorption, but it incompact when the calcining temperature was too low. The optimum condition was at 750 ℃ for 6 h. In the medium of pH 5～8, the adsorption time was 70 min, and capacity of adsorption were 191.51 mg•g－1 for lead, 19.00 mg•g－1 for cadmium and 19.97 mg•g－1 for zinc. The adsorption behavior followed a Freundlich adsorption isotherm and a pseudo-second-order kinetic model. The enthalpy change (ΔH) of the adsorption process was 35.905 kJ•mol－1. At various temperatures, Gibbs free energy changes (ΔG) were negative, and entropy changes (ΔS) were positive. The activation energy (Ea) was 62.430 kJ•mol－1 for the adsorption. These showed that the adsorption was an endothermic and spontaneous physical process. The adsorbed heavy metal ion could be completely eluated using 1 mol•L－1 HNO3. The pre-concentration factors for all studied heavy metal ions were all more than 200. The method has been applied to the preconcentration and FAAS determination of trace lead, cadmium and zinc ion in water samples. The recoveries were 90.3%～103.4%, 91.5%～103.2% and 94.35%～101.1% respectively.

Key words: porous nano-barium-strontium titanate, sorghum straw, biotemplate method, adsorption behavior, heavy metal ion, FAAS