Self-assembled nanocomposite of HKUST-1 and LAPONITE®: towards a hydrogel with high mechanical strength for selective dye adsorption and column chromatographic separation

Abstract

Herein, we report the synthesis of a novel hydrogel nanocomposite, HKUST-1@LP, through the self-assembly of a prototype metal–organic framework (MOF), HKUST-1 and the nanoclay, LAPONITE® (LP). The nanocomposite was characterized by using different techniques including PXRD, FESEM, EDX, FTIR, TGA, rheology, zeta potential analysis and N₂ adsorption measurements. The resulting composite exhibits significantly enhanced dye adsorption/separation properties compared to its individual parent components and has been exploited as a dye adsorbent and stationary phase for gel-column chromatography. It demonstrates superior capabilities in selective dye adsorption, particularly for cationic dyes such as methylene blue (MB), 229 mg g⁻¹, and rhodamine B (RhB), 212 mg g⁻¹, with adsorption kinetics influenced by temperature. Furthermore, the HKUST-1@LP hydrogel separates mixtures of dyes effectively, as was evident from the conducted gel-column chromatography experiments. The HKUST-1@LP hydrogel showcases remarkable mechanical robustness and rheological studies revealed higher storage modulus (G′) and loss modulus (G″) values for the composite compared to pristine LP, withstanding greater strain levels before structural failure (82.7% for HKUST-1@LP hydrogel vs. 52.7% for LP). These enhanced mechanical and functional attributes underscore the composite’s potential for practical applications in selective dye adsorption and chromatographic separation processes.