Aluminum copper bimetallic metal organic gels/sodium alginate beads for efficient adsorption of ciprofloxacin and methylene blue: Adsorption isotherm, kinetic and mechanism studies

Abstract

In this research, a new aluminum-copper bimetallic organic gel was prepared by solvothermal method. It is hoped that the special structure and properties of this new material can be used to remove ciprofloxacin (CIP) and methylene blue (MB) from water to deal with environmental pollution problems. Their morphology and structure were characterized by XRD, FT-IR, XPS, SEM, BET, TGA and zeta potential. It is proved that they have sufficient active sites, large specific surface area (270.5 m2/g), hierarchical porous structure, and strong thermal stability. These properties contribute to their efficient removal of pollutants. Compared with other adsorbents, MOG-4 in this study showed good pollutant removal rate, wide pH adaptability, good anti-interference ability and excellent reuse rate. The maximum adsorption capacity of MOG-4 for CIP and MB was 458.72 mg/ g and 381.68 mg/ g respectively. The adsorption process followed the second-order kinetic model and Freundlich isotherm. More importantly, we constructed MOG-4 @SA beads by immobilizing MOG-4 in sodium alginate (SA) matrix, which not only overcame the shortcomings of difficult recovery and easy agglomeration of powder MOG-4, but also enhanced its adsorption capacity. Seven cycles show that the reuse rate of MOG-4 @SA is more than 84%. The adsorption mechanism involves hydrogen bonding, electrostatic interaction, π-π interaction, hydrophilic/hydrophobic interaction and pore filling. MOG-4 @SA beads adsorbent overcomes the shortcomings of traditional powder adsorbent, which is easy to lose, easy to aggregate and difficult to recover, and broadens the range of use of powder adsorbent and sodium alginate. Therefore, MOG-4 @SA has the advantages of good adsorption performance, high reuse rate, wide range of adaptation, strong anti-interference ability, and is expected to become a promising adsorbent.