Titanium metal organic framework based electrocatalytic membrane for fast antibiotics removal: Synergy of defects and hierarchical pore

Abstract

The spread of antibiotics became a serious risk to human health during wastewater reclamation. Herein, a novel electrocatalytic membrane (ECM) was constructed by facile incorporation of titanium metal organic frameworks (Ti-MOFs) with tunable defect and pore structure into polyvinylidene fluoride (PVDF) membrane for antibiotics removal under electro-assistance. The results showed Ti-MOFs with moderate missing-linker defects and hierarchical pores (Ti-MOFs-1) imparted the membrane with much higher water flux (618.6 L·m−2·h−1·bar−1), oxygen evolution potential (2.16 V), electrochemically active surface area (0.0306 cm2), and lower charge-transfer resistance compared to defect-free Ti-MOFs, thereby rendering higher electrocatalytic activity, increasing tetracycline (TC) removal by more than 40% and reducing the toxicities of intermediates. Interestingly, ECM presented a volcano-type trend in TC removal with the gradual increase of defects and pore size in Ti-MOFs due to the synergistic effect of moderately exposed active sites for generation of •OH and •O2– and hierarchical pore feature for accelerated mass transfer of antibiotics toward the catalytic sites. In addition, the application of ECM in reclamation of simulated municipal wastewater was evaluated. The efficient antibiotics removal efficiency (100%), electrically-driven self-cleaning ability (flux recovery = 100%) and electrochemical stability with low residence time (50.2 s) and energy consumption (0.533 W•h/m3) verify its potential in antibiotics removal.