Mildly oxidized porous covalent triazine frameworks with rapid and high adsorption capability for aqueous organic micropollutants

Abstract

Two microporous and amorphous covalent triazine-based frameworks (CTFs) were synthesized by the low-temperature Friedel–Craft reaction using phenanthrene and anthracene as monomers, and cyanuric chloride as a linker. The synthesized CTFs were then further functionalized by mild oxidation to obtain CTF derivatives (CTF-OXs) with amide and imine groups. The functionalized derivatives showed excellent maximum adsorption capacities for bisphenol A (BPA), bisphenol S (BPS), and 2-naphthol (247, 249, and 376 mg g−1, respectively), which are aqueous organic micropollutants. The maximum adsorption capacities were estimated using the Langmuir and Jovanovic isotherm models, and the adsorption kinetics could be well fitted by the pseudo-second-order kinetics model. The extremely high association constants between the pollutants and the mildly oxidized CTFs surface, calculated by the Langmuir isotherm model, showed a 1:1 complex formation between micropollutants (BPA, BPS, and 2-naphthol) and CTF-OXs. This suggests excellent binding properties for the removal of the selected micropollutants at any concentration level. The thermodynamics parameters for the removal of BPA, BPS, and 2-naphthol showed the adsorption process is feasible and involves physisorption. Hence, CTF-OXs have significant potential for use as effective adsorbents for water decontamination.