Layered Double Hydroxides-Incorporated Thin-Film Nanocomposite Membranes: Emerging Strategies for Sustainable Liquid Separation

Layered double hydroxides (LDHs), a unique class of 2D anionic clays, have recently emerged as promising nanofillers for fabricating thin-film nanocomposite (TFN) membranes. Benefiting from their tunable compositions, adjustable interlayer spacing, intrinsic hydrophilicity, and structural stability, LDHs can be strategically incorporated into different membrane compartments, including substrates, interlayers, selective layers, and even deployed as standalone functional layers, to tailor microstructures and enhance separation performance. This review systematically summarizes the state-of-the-art LDHs-based TFN membranes for liquid separation, covering applications in desalination, boron removal, dye and organic contaminant rejections, and solvent purification. The unique roles of LDHs in breaking the trade-off relationship between permeability and selectivity, improving chlorine resistance, mitigating fouling, and introducing bactericidal or photocatalytic functionalities are highlighted. In addition, recent advances in scalable fabrication strategies, such as in situ growth of LDHs within polyamide matrices, are highlighted for their potential to simplify production and enable large-scale implementation. Despite these encouraging developments, challenges remain in understanding interfacial interactions, optimizing LDHs dispersion, and ensuring long-term operational stability. By consolidating current knowledge and outlining future directions, this work may provide critical insights to design LDHs-incorporated TFN membranes as next-generation materials for sustainable liquid separation.