Solvothermal synthesis of polyoxometalate-modified UiO-66-NH2 for enhanced removal of ciprofloxacin from aqueous solution

Removal of ciprofloxacin (CIP) from wastewater is of significance to protect the environment. In this study, phosphomolybdic acid (H3PMo12O40) -modified metal-organic framework (UiO-66-NH2) materials were prepared by the solvothermal method for the removal of CIP from wastewater. The adsorption performance of H3PMo12O40@ UiO-66-NH2 on CIP was remarkably superior to that of pure UiO-66-NH2. Several experiments with altered conditions, including CIP concentration, contact time, and pH, were explored to understand the adsorption performance of H3PMo12O40@ UiO-66-NH2 on CIP solutions. The experimental results show that when pH = 7, T = 323 K, the amount of H3PMo12O40 is 0.14 g, which is the best CIP adsorption condition for H3PMo12O40@UiO-66-NH2, and the adsorption amount is 164.28 mg g(-1). The adsorption kinetics and isotherms of CIP molecules on the modified UiO-66-NH2 adsorbent showed that they were basically in agreement with the pseudo-second-order kinetic model and Langmuir model, respectively. Thermodynamic parameters indicate that the adsorption process is spontaneous endothermic. After five cycles of experiments, the adsorbent can still remove 81% of the CIP, indicating that it is reproducible and practical for CIP. Hence, the H3PMo12O40@ UiO-66-NH2 has potential application value as an antibiotic's adsorbent.

Automated summary

In this study, a phosphomolybdic acid-modified UiO-66-NH2 metal-organic framework material was successfully prepared as an adsorbent for the removal of ciprofloxacin (CIP) from wastewater. The adsorbent exhibited excellent removal performance under the conditions of pH = 7 and temperature of 323 K. The adsorption kinetics and isotherms of the modified adsorbent were in agreement with the pseudo-second-order kinetic model and Langmuir model, respectively. The adsorption process was found to be spontaneous endothermic. The adsorbent also showed good reusability, with 81% removal efficiency after five cycles of experiments.