EDTA辅助水热法制备不同形貌的氟化镁钠

doi:10.15541/jim20180530

摘要/Abstract

摘要：

以氟化钠、六水合氯化镁为主要原料, EDTA (乙二胺四乙酸二钠盐)为辅助剂, 通过水热法制备出不同形貌的氟化镁钠。考察了溶液pH、反应温度、时间和络合剂对产物形貌和物相的影响, 并对其形成机理进行了探讨。采用扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)等手段对产物形貌和物相进行了表征。结果表明: 在该反应体系中, EDTA既作为原料提供钠离子, 又作为络合剂与镁离子形成络合物; 反应温度、pH和络合剂对产物的形貌和物相有较大影响; 所得产物结晶度高, 有表面光滑的微米立方体晶体和纳米粒子聚集的微米空心球颗粒, 粒径均在1~3 μm之间。

关键词: 水热法, 氟化镁钠, 络合剂, 反应机理

Abstract:

Different morphologies of sodium magnesium fluoride particles were prepared by EDTA-assisted hydrothermal method using sodium fluoride, magnesium chloride hexahydrate as main materials and EDTA (ethylenediaminetetraacetic acid disodium salt) as auxiliary agent. Influence of solution pH, reaction temperature, time and complexing agent on the morphology and phase of the products was investigated, and the formation mechanism was discussed. Samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The results show that the EDTA not only provides sodium ions as raw material, but also forms complex with magnesium ions as a complexing agent in the reaction system. Reaction temperature, pH and complexing agent have great influences on the morphologies and phase of the products. The obtained products have microcube crystals with a smooth surface and micron-sized hollow spheres polymerized with nanoparticles. And the products have high crystallinity with crystal dimension ranging from 1 μm to 3 μm.

Key words: hydrothermal method, sodium magnesium fluoride, complexing agent, reaction mechanism

中图分类号:

O614

许云青,王海增. EDTA辅助水热法制备不同形貌的氟化镁钠[J]. 无机材料学报, 2019, 34(9): 933-937.

XU Yun-Qing,WANG Hai-Zeng. Sodium Magnesium Fluoride Particles of Different Morphologies: Prepared by EDTA-assisted Hydrothermal Method[J]. Journal of Inorganic Materials, 2019, 34(9): 933-937.

图/表 9

图1 不同pH下所得样品的XRD图谱(120 ℃, 24 h)

Fig. 1 XRD patterns of products prepared at different pH (120 ℃, 24 h)

图2 不同pH下所得样品的红外谱图(120 ℃, 24 h)

Fig. 2 FT-IR spectra of products prepared at different pH (120 ℃, 24 h)

图3 不同pH下所得样品的SEM照片(120 ℃, 24 h)

Fig. 3 SEM images of products prepared at different pH (120 ℃, 24 h) (a1, a2) pH=5; (b1, b2) pH=7; (c1, c2) pH=9

表1 不同pH时Mg-EDTA络合物的lgKMgY、lgαY(H)和lgK'MgY

Table 1 lgKMgY, lgαY(H), lgK'MgY of Mg-EDTA complex at different pH

pH	lgK_MgY	lgα_Y(H)	lgK'_MgY
5		6.45	2.19
7	8.64	3.32	5.32
9		1.28	7.36

图4 不同温度下所得样品的SEM照片(pH=9, 24 h)

Fig. 4 SEM images of products prepared at different temperature (pH=9, 24 h) (a1, a2) 80 ℃; (b) 100 ℃; (c) 120 ℃; (d) 140 ℃; (e) 160 ℃

图5 不同时间下所得样品的SEM照片(pH=9, 80 ℃)

Fig. 5 SEM images of products prepared for different time (pH=9, 80 ℃) (a) 2 h; (b) 8 h; (c) 12 h; (d) 24 h

图6 添加和未添加EDTA所得样品的XRD图谱和SEM照片(pH=9, 120 ℃, 24 h)

Fig. 6 (a) XRD patterns of samples prepared with or without EDTA (pH=9, 120 ℃, 24 h) (b) and SEM images without EDTA

图7 EDTA与Mg2+络合反应示意图

Fig. 7 Schematic of EDTA and Mg2+ complexation structure

图8 空心球状氟化镁钠形成机理示意图

Fig. 8 Schematic diagram of the formation mechanism for hollow spherical sodium magnesium fluoride

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