Selective adsorption of organic dyes and iodine by a two-dimensional cobalt(II) metal-organic framework

The development of effective adsorbent materials for capturing organic dyes and iodine is crucial to reduce the environmental impact and ensure human health. In this context, a two-dimensional (2D) Co-based metal-organic framework SDU-CP- was rationally designed with 4-(4-carboxyphenyl)-1,2,4-triazole (Hcpt) and 2,4,6-tri(4-pyridinyl)-1,3,5-triazine (tpt) as organic linkers. The SDU-CP- was comprehensively characterized using single-crystal X-ray diffraction analysis, thermogravimetric analysis, fourier transform infrared spectroscopy, raman spectroscopy, powder x-ray diffraction analysis and UV-vis spectroscopy. Molecular docking were conducted to elucidate potential binding sites on SDU-CP- for effective interactions with RhB and ST. Featuring negatively charged surface and trigonal microporous channels, SDU-CP- exhibits excellent adsorption capacities of organic dyes (919.2 ​mg/g for Rhodamine B and 1565 ​mg/g for Safranine T) as well as iodine (563.0 ​mg/g in solution and 1100 ​mg/g in the vapor phase). The exceptional adsorption performance of SDU-CP- for cationic dyes can be ascribed to the electrostatic interaction facilitated by negatively charged zeta potential and the size-matching principle, whereas the pyridine active sites in channels significantly enhance the binding affinity for iodine. Moreover, SDU-CP- can serve as chromatographic column filters for the rapid adsorption and separation of dyes. The results demonstrate the excellent selective adsorption performance of SDU-CP-, highlighting its potential for environmental and industrial applications.