A novel covalent organic framework with multiple adsorption sites for removal of Hg2+ and sensitive detection of nitrofural

It is urgent to control serious drug pollution and heavy metal ion pollution. Covalent organic framework (COF) is becoming a promising material for the removal of heavy metal ion and adsorption of organic small molecule because of the designed functional sites, ordered pore channel, high specific surface area and abundant π electrons. Herein, 2,4,6-triformylphloroglucinol (TFP) and benzene-1,3,5-tricarbohydrazide (BTH) was used to design a stable yet efficient beta-ketoenamine COF (COFTFP-BTH) adsorbent, which would provide multiple adsorption sites of Hg2+ by dense acylhydrazine. The maximum adsorption capacity of COFTFP-BTH toward Hg2+ achieved 909 mg g−1, coinciding with Langmuir adsorption and pseudo-second-order adsorption kinetic model, with the h value as high as 71.43 mg g−1 min−1. COFTFP-BTH was also grown on NH2-carbon nanotubes (CNT) to form a novel COFTFP-BTH@NH2-CNT composite for sensitive detection of nitrofural (NF). The NF sensor based on COFTFP-BTH@NH2-CNT showed a low detection limit (3.2 nM) and a wide linear range (9.6 nM-100 μM). The excellent performances were also attributed to the ordered channels of COFTFP-BTH exposing more adsorption sites of Hg2+ and NF, as well as the good stability of beta-ketoenamine COFTFP-BTH.