Structural characterization and functional evaluation of modified layered double hydroxides (LDHs) and their integration into cellulose acetate fibers for metal ion adsorption

In this study, the successful synthesis, structural integrity, and functional modification of layered double hydroxides (LDHs) incorporating various metal systems (MgAl, CaAl, BaAl) were comprehensively characterized using FT-IR, XRD, and SEM-EDX analyses. FT-IR spectra confirmed the incorporation of organic dyes, Arsenazo and Thorin, into the LDH matrix through distinctive O–H stretching, interlayer water bending, and anionic interaction bands. Comparative spectral analysis revealed that metal cation identity significantly influenced hydration behavior and molecular interactions within the LDH interlayers. XRD results indicated that while pristine LDHs exhibited well-ordered layered structures, Arsenazo-modified LDHs displayed enhanced crystallinity, whereas Thorin-modified LDHs exhibited broader diffraction peaks, suggesting partial amorphization. Among the studied systems, BaAl-LDH demonstrated the highest degree of crystallinity, followed by MgAl-LDH and CaAl-LDH, indicating that intercalation efficiency is highly metal-dependent. SEM-EDX analysis provided morphological and elemental insights, with BaAl-LDH showing compact aggregates, CaAl-LDH exhibiting granular morphology, and MgAl-LDH presenting highly porous structures favorable for adsorption. Elemental mapping confirmed successful synthesis and slight presence of synthesis-related impurities. Furthermore, composite cellulose acetate (CA) fibers embedded with these LDHs maintained structural stability while exhibiting varied porosity and surface texture based on the type of LDH and its modification. Modified fibers demonstrated morphological changes such as surface roughening or localized fracturing, suggesting potential trade-offs between mechanical stability and sorption efficiency. Overall, the results underscore the effectiveness of LDH modification and their integration into fibrous matrices for environmental applications. Tailored LDH-CA composites, especially those with high porosity and crystallinity, offer significant potential for the selective adsorption of metal ions such as Th(IV), La(III), and Y(III), supporting their use in water purification and related remediation technologies.