Highly Effective Removal of Ciprofloxacin Antibiotic from Water by Magnetic Metal-Organic Framework

The presence of antibiotic ciprofloxacin (CIP) in pharmaceutical wastewaters is dangerous when their concentrations exceed the allowable limits. Thus, eliminating CIP from pharmaceutical wastewaters is an essential issue. In this work, magnetic MOFs, named Fe3O4/Zn-3(BTC)(2) MMOF, were successfully synthesized and used for the adsorption of CIP. Compared with Cu-3(BTC)(2) and Fe3O4/Cu-3(BTC)(2) MMOF, the Fe3O4/Zn-3(BTC)(2) MMOF exhibited the best CIP-adsorption performance, with a maximum removal rate of 72.15% due to the large pore size, abundant adsorption sites and functional groups of MOFs, and the magnetic properties of the Fe3O4 nanorod. The influencing factors in the adsorption process, including oscillation time and pH value, were discussed, and the best adsorption performance was obtained when the pH was 3.84 and the oscillation time was 90 min. Furthermore, the removal rate of the Fe3O4/Zn-3(BTC)(2) MMOF still reached 31.45% after five instances of reuse, revealing its great regeneration and reusability. The results of the adsorption-kinetics studies showed that the adsorption process of CIP by Fe3O4/Zn-3(BTC)(2) MMOF followed the pseudo-second-order kinetic model and was mainly chemical adsorption. Based on the results above, Fe3O4/Zn-3(BTC)(2) MMOF is recommended as a highly efficient adsorbent for the removal of CIP from pharmaceutical wastewaters.