The preparation of new covalent organic framework embedded with silver nanoparticles and its applications in degradation of organic pollutants from waste water

A covalent organic framework (COF) featuring a unique light porous structure and silver nanoparticles shows high efficiency in the degradation of environmental pollutants. However, the combination of a COF with silver nanoparticles has never been reported until now. Toward this end, 2,4,6-tris-(4-formyl-phenoxy)-1,3,5-triazine (TPT-CHO) and hydrazine hydrate were selected as the construction units of the COF material (TPHH-COF), which possesses rich nitrogen and oxygen sites. Then a new type of composite catalyst (Ag@TPHH-COF) was successfully obtained by solution infiltration. The obtained materials were also fully characterized by standard methods. The results showed that the silver nanoparticles (with diameters of 5 +/- 3 nm) were uniformly dispersed on the surface and in the interlayer gaps of the TPHH-COF substrate. Catalytic studies showed that Ag@TPHH-COF could catalyze the reduction of the various nitroaromatic compounds (NACs) with high efficiency, such as 4-nitrophenol, 2-nitrophenol, 4-nitroaniline, nitrobenzene, 4-nitrotoluene and 1-butyl-4-nitrobenzene. Ag@TPHH-COF could also catalyze the reduction of organic dyes such as Rhodamine B (RhB), Methylene Blue (MB), Methyl Orange (MO) and Congo Red (CR). Moreover, Ag@TPHH-COF has good reusability and high recovery.