Zn⁃Mg⁃Al LDO的制备及其除氟性能研究

doi:10.12422/j.issn.1006-396X.2023.05.010

摘要/Abstract

摘要：

半导体、电镀、冶金和陶瓷行业排放高浓度含氟废水，因此天然水中的氟化物污染已成为一个全球性问题，而Zn?Mg?Al LDO是很好的吸附材料。在n（Zn²⁺）/n（Mg²⁺）/n（Al³⁺）、反应温度不同的条件下，采用共沉淀法合成Zn?Mg?Al LDH，并将Zn?Mg?Al LDH在不同温度下焙烧制得Zn?Mg?Al LDO；利用X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT?IR）、BET比表面积测试法等方法，探究了Zn?Mg?Al LDO的结构和性质；对50 mL质量浓度为20.0 mg/L的NaF溶液进行吸附实验，考察了Zn?Mg?Al LDO吸附去除氟离子的性能。结果表明，在n（Zn²⁺）/n（Mg²⁺）/n（Al³⁺）＝2∶1∶1、反应温度为75 ℃、焙烧温度为400 ℃的条件下制备的Zn?Mg?Al LDO吸附去除氟离子的性能最好，氟离子的吸附去除率达到85.39%；Zn?Mg?Al LDO具有水滑石特征峰，晶型良好，呈层状结构；Zn?Mg?Al LDO为介孔材料，其比表面积为103.15 m²/g。此外，还研究了吸附过程的动力学和吸附机理。结果表明，吸附过程符合Langmuir吸附等温线和准二级动力学方程。

关键词: 锌镁铝水滑石, 类水滑石, 吸附剂, 氟, 层状双氢氧化物

Abstract:

The semiconductor, electroplating, metallurgy, and ceramic industries discharge high concentration fluoride containing wastewater, making fluoride pollution in natural water a global problem.Thus， Zn?Mg?Al LDO is a good adsorbent material. Under different reaction temperatures of n（Zn²⁺）/n（Mg²⁺）/n（Al³⁺）, Zn?Mg?Al LDH was synthesized by co?precipitation method, and Zn?Mg?Al?LDH was calcined at different temperatures to obtain Zn?Mg?Al?LDO. X?ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT?IR) and BET specific surface area testing methods were used to study the structure and properties of Zn?Mg?Al LDO. The adsorption experiment was conducted on 50 mL of NaF solution with an mass concentration of 20.0 mg/L to investigate the performance of Zn?Mg?Al LDO in adsorbing and removing fluoride ions. The results showed that the Zn?Mg?Al LDO prepared under the conditions of n（Zn²⁺）/n（Mg²⁺）/n（Al³⁺）=2∶1∶1, reaction temperature of 75 ℃, and calcination temperature of 400 ℃ exhibited the best adsorption and removal performance of fluoride ions, with an adsorption and removal rate of 85.39%. Zn?Mg?Al LDO has characteristic peaks of hydrotalcite, good crystal structure, and a layered structure. Zn?Mg?Al LDO is a mesoporous material with a specific surface area of 103.15 m²/g. In addition, the kinetics and adsorption mechanism of the adsorption process were also studied. The results indicate that the adsorption process follows the Langmuir adsorption isotherm and quasi second?order kinetic equation.

Key words: Zn?Mg?Al hydrotalcite, Kind of hydrotalcit, Adsorbent, Fluorine, Layered double hydroxide

中图分类号:

TB332

李敏, 李政, 顾贵洲, 于喜洋, 王辉. Zn⁃Mg⁃Al LDO的制备及其除氟性能研究[J]. 石油化工高等学校学报, 2023, 36(5): 73-80.

Min LI, Zheng LI, Guizhou GU, Xiyang YU, Hui WANG. Study on the Preparation and Fluoride Removal of Zn⁃Mg⁃Al LDO[J]. Journal of Petrochemical Universities, 2023, 36(5): 73-80.

图/表 17

图1 Zn?Mg?Al LDO的XRD图谱

Fig.1 XRD patterns of Zn?Mg?Al LDO

表1 Zn?Mg?Al LDO的晶体参数

Table 1 Crystal parameters of Zn?Mg?Al LDO

参数	数值
d₀₀₃/nm	0.766 4
d₁₁₀/nm	0.177 3
a/nm	0.354 6
c/nm	2.299 2

图2 Zn?Mg?Al LDO吸附前后的SEM图像

Fig.2 SEM images of Zn?Mg?Al LDO before and after adsorption

图3 Zn?Mg?Al LDO的FT?IR图谱

Fig.3 FT?IR spectra of Zn?Mg?Al LDO

表2 Zn?Mg?Al LDO的比表面积、孔径、孔容的BET计算结果

Table 2 BET calculations of specific surface area, pore size, and pore volume of Zn?Mg?Al LDO

参数	数值
比表面积/(m²·g^-1)	103.15
孔径/nm	27.26
孔容/(mL·g^-1)	0.702 4

图4 Zn?Mg?Al LDO的吸附?脱附等温线

Fig.4 Adsorption?desorption isotherm of Zn?Mg?Al LDO

图5 n(Zn2+)/n(Mg2+)对Zn?Mg?Al LDO吸附性能的影响

Fig.5 Effect of n(Zn2+)/n(Mg2+) on the adsorption performance of Zn?Mg?Al LDO

图6 反应温度对Zn?Mg?Al LDO吸附性能的影响

Fig.6 Effect of reaction temperature on athe adsorption performance of Zn?Mg?Al LDO

图7 焙烧温度对Zn?Mg?Al LDO吸附性能的影响

Fig.7 Effect of calcination temperature on adsorption performance

图8 Zn?Mg?Al LDO投加量对吸附性能的影响

Fig.8 Effect of Zn?Mg?Al LDO dosage on adsorption performance

图9 NaF质量浓度对吸附性能的影响

Fig.9 Effect of NaF mass concentration on adsorption properties

图10 溶液的pH对Zn?Mg?Al LDO吸附性能的影响

Fig.10 Effect of pH of solution on the adsorption performance of Zn?Mg?Al LDO

图11 循环再生次数对Zn?Mg?Al LDO吸附性能的影响

Fig.11 Effect of cycle regeneration times on the adsorption performance of Zn?Mg?Al LDO

图12 Mg?Al?Fe LDO的拟一级动力学方程和拟二级动力学方程

Fig.12 Mg?Al?Fe LDO quasi?first?order and quasi?second-order dynamic equations

表3 吸附动力学模型参数

Table 3 Adsorption kinetic model parameters

温度

/℃

拟一级动力学方程

拟二级动力学方程

k₁/min^-1

12

k₂/(g·mg^-1·min^-1)

22