Functionalized metal-organic frameworks for effective removal of rocephin in aqueous solutions

The porous metal-organic frameworks, MIL-101, MIL-101-SO3H and MIL-101-NH2 were used for the removal of harmful drug (rocephin) from water via adsorption. The kinetics study suggests that the adsorption onto all the MOFs follows the pseudo-second-order model. The adsorption isotherms results suggest that the adsorption onto MIL-101 and MIL-101-NH2 fits well with Langmuir model and the maximum adsorption capacities are calculated to 204.08 mg g-1 and 277.78 mg g-1, respectively; while the adsorption onto MIL-101-SO3H cannot fit well with both Langmuir and Freundlich models and the maximum adsorption capacity in the experiment is 25 mg g-1. Furthermore, the effect of pH as well as the adsorption mechanism was analysed systematically. It was found that electrostatic interaction as well as hydrogen-bond interaction plays dominant roles in adsorption of rocephin, and MIL-101-NH2 with abundant amino groups can exhibit better adsorption capacity and removal percentage towards rocephin than MIL-101, MIL-101-SO3H, and some other common adsorbents. In addition, co-existed Zn(NO3)2 can induce a large improvement of rocephin adsorption performance of MIL-101-NH2. At last, MIL-101-NH2 demonstrates to be a renewable adsorbent. In conclusion, we suggest MIL-101-NH2 is a promising adsorbent for effective removal of rocephin in water.