ZIF-8-templated synthesis of hollow porous layered double hydroxide/cellulose aerogel composites for efficient removal of antibiotics from aqueous solution

Abstract

Layered double hydroxides (LDHs), despite their unique layered structure advantageous for removing high-molecular-weight antibiotics, suffer from limitations such as small specific surface area, uncontrollable morphology, and irregular spatial structure compared to metal–organic frameworks (MOFs). Therefore, in this study, ZIF-8 was used as a template to prepare LDHs with a hollow mesoporous structure (ZNF-HS), merging the benefits of both materials. ZNF-HS was then stably incorporated into sodium carboxymethylcellulose aerogels, resulting in ZNF-HS@CMC composites that facilitated easy solid–liquid separation and were effective in removing tetracycline (TC) and ciprofloxacin (CIP) from aqueous solution. Characterization of ZNF-HS@CMC was conducted using SEM, TEM, XRD, FTIR, XPS, BET, and TGA. ZNF-HS@CMC exhibited a specific surface area of 248.753 m²·g⁻¹ and a pore volume of 0.568 cm³·g⁻¹, surpassing traditional LDHs. The removal of TC and CIP by ZNF-HS@CMC followed the pseudo-second-order kinetic and Langmuir models, with maximum sorption capacities of 513.772 and 442.515 mg·g⁻¹, respectively. pH significantly influenced the removal efficiencies, while NaNO₃ concentration up to 0.25 mol·L^-1 had negligible impact, maintaining removal efficiencies above 90 %. After five sorption–desorption cycles, the removal efficiencies remained above 80 %. The removal of TC and CIP by ZNF-HS@CMC was primarily achieved through surface complexation, hydrogen bonding, and π-π interactions, with electrostatic interactions also contributing. Overall, ZNF-HS@CMC exhibits the advantages of easy recycling, good reusability, strong resistance to salt interference, and high sorption capacity, making it promising for practical applications in the efficient removal of antibiotics from water.