Preparation of Magnesium-Aluminum Layered Double Hydroxides by Electrodeposition of Salt Lake Bischofite

doi:10.12068/j.issn.1005-3026.2025.20240009

Abstract

Abstract:

The preparation of magnesium-aluminum layered double hydroxides （MgAl-LDHs） from industrial bischofite by-products in salt lake region was achieved via electrochemical deposition method， with systematic investigation of deposition parameters. The structural and properties of the products under different conditions were investigated utilizing X-ray diffraction （XRD）， scanning electron microscopy （SEM）， Fourier transform infrared spectroscopy （FT-IR）， and other analytical methods. The results show that MgAl-LDHs materials with regular morphology can be prepared by electrochemical deposition method. The product under the condition of large current density will undergo severe agglomeration. Under lower electrolyte concentration conditions， the interlayer spacing of products increases， which is beneficial for crystal growth. Excessive Mg and Al mass ratio is not conducive to product formation. The preparation process of products involved layer-by-layer detachment near electrode plates， where interfacial supersaturation influenced crystallinity.

Key words: bischofite, electrodeposition, magnesium-aluminum layered double hydroxides （MgAl-LDHs）, agglomeration, precipitation

CLC Number:

TF 111.52

Rui ZHANG, Jin-gou ZHOU, Guang-chao MA, Yue-zhong DI. Preparation of Magnesium-Aluminum Layered Double Hydroxides by Electrodeposition of Salt Lake Bischofite[J]. Journal of Northeastern University(Natural Science), 2025, 46(6): 50-55.

Figures/Tables 17

Table 1 Composition of bischofite from Qinghai salt

离子名称	质量分数	离子名称	质量分数
Mg²⁺	23.19	Cl^-	75.13
Ca²⁺	0.21	SO $4 2 -$	0.51
K⁺	0.27	PO $4 2 -$	≤0.01
Na⁺	0.51	BO $3 2 -$	0.01
Li⁺	0.06	其他	≤0.01

Table 1 Composition of bischofite from Qinghai salt

离子名称	质量分数	离子名称	质量分数
Mg²⁺	23.19	Cl^-	75.13
Ca²⁺	0.21	SO $4 2 -$	0.51
K⁺	0.27	PO $4 2 -$	≤0.01
Na⁺	0.51	BO $3 2 -$	0.01
Li⁺	0.06	其他	≤0.01

Fig.1 Flow chart of MgAl-LDHs preparation by electrodeposition method

Fig.2 Schematic diagram of electrodeposition process

Fig.3 XRD patterns of products at different current densities

Table 2 XRD analysis results of product LDHs under different current densities

晶面	参数	电流密度/（mA·cm^-2）
晶面	参数	10	11	12	13	14
（003）	2θ/（°）	11.086 93	11.052 02	11.065 01	11.136 14	10.992 35
	d/nm	0.797 4	0.799 9	0.799 0	0.793 9	0.804 2
	FWHM/（°）	1.852 12	1.899 41	1.743 82	1.685 17	1.789 38
（110）	2θ/（°）	61.240 37	61.178 03	61.185 67	61.326 67	61.062 35
	d/nm	0.151 2	0.151 4	0.151 4	0.151 0	0.151 6
	FWHM/（°）	2.362 47	2.173 74	2.032 36	2.250 27	2.181 61

Fig.4 Plot of product mass versus current density

Fig.5 SEM images of products at different current densities

Fig.6 XRD patterns of product LDHs under different electrolyte concentrations

Table 3 XRD analysis results of product LDHs under

晶面	参数	电解液浓度/（mol·L^-1）
晶面	参数	0.1	0.2	0.3
（003）	2θ/（°）	11.130 15	11.135 25	11.208 04
	d/nm	0.794 3	0.794 0	0.788 8
	FWHM/（°）	1.722 4	1.793 52	1.517 18
（110）	2θ/（°）	61.234 33	61.243 21	61.093 48
	d/nm	0.151 2	0.151 2	0.151 6
	FWHM/（°）	2.278 76	2.054 61	1.800 25

Fig.7 SEM images of product LDHs under different electrolyte concentrations

Fig.8 XRD patterns of products with different Mg and Al mass ratios

Table 4 XRD analysis results of product LDHs with

晶面	参数	镁铝质量比
晶面	参数	2∶1	3∶1	4∶1
（003）	2θ/（°）	11.202 74	11.100 65	11.039 73
	d/nm	0.789 2	0.796 4	0.800 8
	FWHM/（°）	1.549 79	1.775 94	1.791 69
（110）	2θ/（°）	61.040 84	60.969 30	60.927 71
	d/nm	0.151 7	0.151 8	0.151 9
	FWHM/（°）	2.212 44	2.556 96	2.779 04

Fig.9 XRD patterns of electrodeposition products

Fig.10 FT-IR spectra of electrodeposition products

Fig.11 SEM images of electrodeposition products

Fig.12 EDS-mapping diagram of electrodeposition products

Fig.13 Element analysis diagram of electrodeposition products

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