Synthesis of aqueous media stable MIL101-OH/chitosan for diphenhydramine and metronidazole adsorption.

In this study, pristine MIL101(Cr) was modified to synthesize hydroxyl-functionalized (MIL101(Cr)-OH) and chitosan (CS)-coated (MIL101(Cr)-OH/CS) metal-organic frameworks (MOFs) to enhance adsorption capacity and reusability, respectively. The synthesized adsorbents were characterized by XRD, FTIR, and BET analyses. The kinetics behavior and the equilibrium adsorption of diphenhydramine (DPH) and metronidazole (MNZ) from aqueous solution on the synthesized adsorbents and a commercial activated carbon were compared at 25°C. The pH-dependent of the adsorption capacity and reusability of MIL101-OH/CS were investigated. The results showed that upon adding OH functional group and chitosan polymer, the adsorption capacity increased; the DPH adsorption capacity on MIL101-OH and MIL101-OH/CS was 634 and 573 mg/g, respectively. Also, the maximum adsorption capacity of MNZ on MIL101-OH/CS was 600 mg/g, which was twice the adsorption capacity of MIL101 and four times the adsorption capacity of the commercial activated carbon. The equilibrium and kinetics behavior results were in good agreement with Langmuir and the pseudo-second-order models, respectively. The DPH and MNZ adsorption mechanisms on MIL101-OH/CS were hydrogen bonding and electrostatic interactions, respectively.