Bio-inspired fabrication of hierarchically porous Mg–Al composites for enhanced BSA adsorption properties

• Hierarchically structured Mg–Al composites were successfully prepared.
• Multiscale architectures were fabricated by improved biotemplate method.
• Crystal growth of LDHs was strongly dependent on urea content.
• The biomorphic composites are quite effective in BSA adsorption.

In this paper, hierarchically porous LDHs/Al2O3 composites are successfully fabricated in a large scale by combining the biological template method (for morph-Al2O3) and hydrothermal method (for LDHs). The morph-Al2O3 with fiber structure is prepared by template-directed synthesis employing cotton fibers as bio-templates. Then, the 2D LDHs nanoplatelets are fabricated into complex 3D architectures by in situ growth on surface Al2O3 fibers in a closed hydrothermal system, forming the hierarchical macro-mesoporous LDHs/Al2O3 composites. The N2 sorption analyses confirmed that the calcined composites have uniform mesochannels (7.58 nm), high surface area (292.51 m2/g), and large pore volume (0.55 cm3/g). Meanwhile, the macroporous structures fabricated by LDH nanoplatelets can be directly observed in morphology analysis. In LDHs crystal growth process, the controlling mechanism was discussed in detail according to the crystal growth kinetics and thermodynamics. As compared to calcined LDHs particles, the calcined composites have excellent adsorption properties. The efficient adsorption (90.27%) of BSA from solution suggests that the composites are potentially useful in BSA bioseparation.

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