In situ self-assembly of ZIF-8@sodium alginate composite hydrogels for enhanced adsorption of Cu2+ Ions

With the advancement of science and technology, the issue of wastewater pollution has escalated, necessitating urgent attention to wastewater treatment . In this study, a highly efficient adsorbent for Cu 2+ was successfully synthesized through in situ self-assembly using Ca 2+ as the cross-linking agent in ZIF-8@ALG composite hydrogel. The results demonstrated that the incorporation of Ca 2+ as the cross-linker enhanced both adsorption capacity and swelling properties of ZIF-8@ALG composite hydrogel. Adsorption performance evaluation revealed that the hydrogel followed pseudo-second-order kinetic model for Cu 2+ adsorption and Freundlich isotherm model with a theoretical maximum adsorption capacity of 309.57 m g −1 . Thermodynamic analysis indicated that Cu 2+ adsorption onto the hydrogel occurred spontaneously with heat absorption. Furthermore, excellent reusability was observed after five cycles of usage without significant loss in adsorption efficiency. Overall, these findings highlight the potential application of ZIF-8@ALG composite hydrogel as an effective solution for wastewater remediation and recovery of heavy metal ions.