Abundant and diverse functional groups of adsorbents are essential for their adsorption performances. Herein, we report a strategy to construct highly efficient ammonia nitrogen adsorbents by installing multiple ion-exchange complexation coordination-hydrogen bonding sites onto covalent organic frameworks (COFs). As a proof of concept, we prepared a COF (TpPa-SO3H) via a modified mechanical grinding synthetic method and then obtained a sulfonated COF bearing single Cu sites (TpPa-SO3Cu0.5) by post-loading. Benefiting from the highly exposed active sites and ordered COF channels, TpPa-SO3Cu0.5 exhibited the highest adsorption kinetics among reported ammonia nitrogen adsorbents proven by the highest pseudo-second-order adsorption rate constant (k2) of 8.97 g mg-1 min-1 with its maximum adsorption capacity (30.45 mg N g-1) higher than most adsorbents (<0.001-0.994 g mg-1 min-1 and 0-25 mg N g-1). Furthermore, TpPa-SO3Cu0.5 exhibited excellent adsorption selectivity with its selective coefficient 328 times as high as that of TpPa-SO3H in real water (10 mg N L-1, pH = 10). It also showed good stability and recyclability with a high ammonia recycle ratio (95.1%) after 5 adsorption-regeneration cycles. These findings pave a new way to develop unique COFs as platforms for ultrafast and selective pollutants in water and wastewater treatment.
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© 2023 American Chemical Society.
- fast adsorption kinetics
- high selectivity
- removal of ammonia nitrogen
ASJC Scopus subject areas
- Chemical Engineering (miscellaneous)
- Environmental Chemistry
- Process Chemistry and Technology
- Chemical Health and Safety