Mussel-inspired synthesis of covalent organic framework and MXene composite for high-performance adsorption of diclofenac sodium

The development of highly effective strategies for the removal of diclofenac sodium is essential to mitigating the threat to public health. This study introduces an adsorbent based on covalent organic framework functionalized MXene, fabricated via a mussel-inspired approach. Initially, MXene was coated with polydopamine through dopamine self-polymerization, introducing amino groups to its surface. Subsequently, the covalent organic framework was assembled onto the surface of MXene. The synthesized adsorbent was employed for the removal of diclofenac sodium, and various factors, including pH, ionic strength, and the presence of inorganic ions, influencing its adsorption performance were systematically examined. This heterostructure composite integrated the advantageous properties of both MXene and covalent organic framework, and exhibited excellent adsorption selective toward diclofenac sodium, with a high adsorption capacity of 495 mg/g for diclofenac sodium and a rate constant k₂ of 0.2134 g/mg/min, surpassing most previously reported adsorbents. Furthermore, the adsorbent retained an adsorption efficiency exceeding 90 % for DCF even after 20 consecutive reuse cycles. Through various characterization analysis, the primary driving forces for diclofenac sodium adsorption were identified as hydrophobic, π-π, anion-π, hydrogen bonding, and electrostatic interactions. Notably, this composite exhibited exceptional adsorption performance for diclofenac sodium in honey, milk, eggs, and lake water samples, highlighting its strong potential for practical applications.