Hierarchical porous spherical-shaped conjugated microporous polymers for the efficient removal of antibiotics from water
Herein, two conjugated microporous polymers (CMPs) containing dual heteroatoms (named as CMPSNs) were synthesized using 4,7-dibromobenzo[c][1,2,5]thiadiazole and alkynyl monomers as the building blocks though a Sonogashira–Hagihara cross-coupling reaction for the efficient removal of antibiotics from water. Fourier transform infrared spectroscopy (FT-IR), 13C CP/MAS solid-state NMR, ultraviolet (UV) adsorption spectroscopy and fluorescence spectroscopy were used to confirm the structure of the resulting CMPSNs. Under our synthesis conditions, CMPSNs with interesting morphologies were obtained, where the macroscopically porous network structure was composed of aggregated hierarchical micrometre-sized microporous spheres. Employing tetracycline as a model antibiotic, for the first time, the performance of the CMPSNs for the removal of tetracycline from water was systematically investigated. The results of the adsorption kinetics of tetracycline showed that the adsorption mechanism of the resulting polymers followed a pseudo-second-order model. Moreover, the adsorption behaviour of CMPSNs for tetracycline fitted well with the Freundlich model. In addition, the adsorption thermodynamics indicated that the adsorption is an endothermic process, and it was also found that the temperature was beneficial to the adsorption and that the adsorption process was spontaneous. The findings obtained from this work make the CMPSNs promising candidates for the capture of tetracycline, which may open a new opportunity to address certain environmental issues, especially from the global-scale severe water pollution arising from antibiotics.