Experimental study of adsorption of amoxicillin residue from water samples using nanocomposite based on zirconium metal-organic frameworks and porous polymers

Antibiotics as emerging pollutants are harmful to environmental health. Therefore, this study was conducted to investigate the efficiency of Uio-66-NH2@CS-Iso-Gu nanohybrid for the removal of amoxicillin (AMX) from aqueous solutions.

In this study, for the first time, guanidine and isocyanate monomers are cross-linked with chitosan. The combination of this polymer with organometallic compounds contributes to its chemical/thermal stability and reusability. Uio-66-NH2@CS-Iso-Gu nanohybrid was characterized using X-ray diffraction (XRD), Scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), and BET methods. Also, the effects of pH, initial concentration of AMX, contact time, and temperature were evaluated. Moreover, isotherm, kinetic and thermodynamics studies were performed.

The results of TGA analysis showed that Uio-66-NH2@CS-Iso-Gu nanohybrid was resistant to temperatures up to 400 °C. Also, optimal adsorption of AMX occurred in the first 25 min. The synthesized nanohybrid has a surface area of 101.2 m2/g and a type IV isotherm. Acidic groups were present on the synthesized nanohybrid surface based on the pHpzc = 4.7. Langmuir (for 25 °C and 45 °C) and Freundlich (for 65 °C) isotherm models and pseudo-second-order kinetic models are more appropriate to fit the adsorption data with the experimental data. The maximum adsorption capacity of the synthesized nanohybrid was equal to 56.49, 40.65, and 0.382 mg/g at temperatures of 25°C, 45°C, and 65°C, respectively. Based on the findings, Uio-66-NH2@CS-Iso-Gu nanohybrid could be used for up to five cycles without significantly reducing their performance.

The results showed that Uio-66-NH2@CS-Iso-Gu nanohybrid has a significant efficiency for removing AMX and could be used as an effective adsorbent for the treatment of wastewater containing pharmaceutical residues.