NaCl template-assisted synthesis of self-floating COFs foams for the efficient removal of sulfamerazine

The preparation of hierarchical porous covalent organic frameworks (HP-COFs) is of great significance due to their inherent porosity and low density. However, it is still very challenging owing to the poor machinability of COFs. Herein, a simple and cost-efficient strategy for the synthesis of HP-COFs was proposed. In particular, p-toluenesulfonic acid and NaCl, both of which can be recycled, are utilized as catalyst and template, respectively. The resulting HP-TpBD-900 featuring abundant macropore and mesopore as well as large specific surface area (~700 m2 g-1) possessed self-floating ability and was turned out to be a promising adsorbent for the efficient removal of sulfamerazine (SMR) in aqueous solution. The maximum adsorption capacity is 168 mg g-1, which is more than twice in comparison to that of material prepared without NaCl template. In addition, no significant decrease in adsorption capacity was observed after 5 cycles. Furthermore, the density functional theory (DFT) method was utilized to elucidate the adsorption mechanism, which could be dominated by hydrogen bonding and C-H···π interaction. This work not only provides a new strategy for the synthesis of HP-COFs, but also contributes to boosting the application of COFs in the field of wastewater treatment.