Positively charged covalent organic framework modified magnetic chitosan as a smart device for efficient diclofenac sodium removal from water

In the current research for the first time, the new magnetic chitosan-coated triazine-based covalent organic frameworks (CS/Fe3O4@TCOFs) were fabricated relying on the unique characteristics of chitosan (CS) and used for the adsorptive removal of diclofenac sodium (DS). The bio-adsorbent was studied by common characterization techniques. The calculated magnetic saturation (Ms 34.49 emu/g) revealed that the CS/Fe3O4@TCOFs can be easily separated by an external magnetic field. More importantly, it displayed a nanoporous structure with about 846.87 m2/g specific surface area in BET analysis. The maximum DS adsorption capacity was calculated at about 333.33 mg/g at 25 degrees C (pH 5) in the initial 50 mg/L concentration. The adsorption data were well fitted with the pseudo-second-order kinetics model, R2 0.9986, and also the Langmuir isotherm thermodynamic model, R2 0.9898. Additionally, the CS/Fe3O4@TCOFs showed excellent adsorption capacity after six times regeneration. These initial findings are expected to inspire further design and fabrication of effective bio-adsorbents for promising practical applications.