Influence of Polyvinyl Alcohol Modification on Lithium-Magnesium Separation of Two-Dimensional Montmorillonite Channel Membrane

doi:10.16552/j.cnki.issn1001-1625.2025.0875

Abstract

Abstract:

Lithium is a key strategic resource to support the new energy revolution， and the total amount of China’s salt lake lithium resources holds a dominant position globally. However， Chinese salt lakes commonly suffer from a high magnesium-lithium ratio， which poses a significant challenge for the efficient separation of lithium and magnesium. This study proposed the use of polyvinyl alcohol （PVA）-modified montmorillonite nanosheets. By precisely controlling the gradient amount of PVA， the channel height of montmorillonite nanosheets was regulated， enabling the highly efficient separation of lithium and magnesium. Furthermore， this work elucidated the mechanism by which PVA modulates the channel height of montmorillonite nanosheets. It is found that PVA can be connected to montmorillonite nanosheets through hydrogen bonds， and enters the montmorillonite layers through intercalation， regulating the channel height of two-dimensional montmorillonite membranes， and achieving efficient separation of lithium and magnesium ions. The separation factor of lithium and magnesium in the simulated brine of the modified membrane can reach up to 92.61， which is 20 times higher than that of the unmodified membrane. The modified membrane demonstrates excellent lithium and magnesium separation capability in brine with high salt concentrations and coexisting multiple cations. The magnesium ion rejection rate remains stable at approximately 97%， and the flux is consistently maintained at a level of approximately 30 L·m^-2·h^-1 after 48 h of long-term stable operation.

Key words: montmorillonite, polyvinyl alcohol, two-dimensional nanosheet, nanochannel membrane, lithium-magnesium separation

CLC Number:

V254.3

WANG Jierui, ZHAO Yunliang, WANG Zhenlei, ZHANG Tingting, ZHANG Xin, LI Ying. Influence of Polyvinyl Alcohol Modification on Lithium-Magnesium Separation of Two-Dimensional Montmorillonite Channel Membrane[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(2): 675-683.

Figures/Tables 10

Fig.1 XRD patterns of MMTM and P-MMTM films with different PVA amount

Fig.2 FTIR spectra of MMTM and P-MMTM films

Fig.3 XPS analysis of MMTM and P-MMTM films

Fig.4 SEM images of MMTM and P-MMTM films

Fig.5 Film roughness and hydrophilicity characterization

Fig.6 Transfer rate and mass transfer activation energy of lithium-magnesium ions in P-MMTM film

Fig.7 Separation performance of lithium-magnesium infilms under different PVA dosages

Fig.8 Mg2+ retention rate and Li+ transmittance of MMTM and P-MMTM films in lithium-magnesium mixed solutions with different salt concentrations

Fig.9 Mg2+ retention rates and Mg2+/Li+ separation selective of MMTM and P-MMTM films under different coexisting ion systems

Fig.10 Long-term stability of P-MMTM film

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