Synthesis of Size-Controllable Urchin-Like Covalent Organic Frameworks for Adsorption of Nitrophenols

The adsorption of nitrophenols by covalent organic frameworks (COFs) has gained increasing attention, due to their feasible designability, which could provide abundant open active sites for their binding to nitrophenols. Herein, we developed a novel method to synthesize uniform urchin-like COFs (TTA-DVA-COFs) with tunable sizes using a temperature-controlling method at atmospheric pressure. The size of the TTA-DVA-COFs can be tuned and controlled gradually from 0.95 μm to 2.85 μm as the synthesis temperature decreases from 80 °C to 20 °C. By using the principle that the interlaced benzene rings, imine bonds (C=N) and triazine structures of TTA-DVA-COF can capture free nitrophenols through hydrogen bonding and conjugation interaction, the COFs can be used as an efficient adsorbent for adsorption and removal of nitrophenols, especially, o-nitrophenol. The maximum adsorption capacity of o-nitrophenol is 695.43 mg/g, which is much higher than previously reported adsorbents. The research provides a new strategy for the controllable synthesis of uniform COFs and extends the application of COFs as efficient adsorbents for the removal of nitrophenols