Crystalline Covalent Organic Frameworks from Triazine Nodes as Porous Adsorbents for Dye Pollutants

Abstract

The development of covalent organic frameworks (COFs) with nodes and spacers, designed to maximize their functional properties, is a challenge. Triazines exhibit better electron affinity than benzene-based aromatic rings; therefore, structures based on 1,3,5-substituted triazine-centered nodes are more stable than those from 1,3,5-benzene-linked COFs. Compared to COFs prepared from flat, rigid sp2 carbon-linked triazine nodes, the O-linked flexible tripodal triazine-based COF demonstrates several unpredictable properties such as an increase in crystallinity and cavity size. In this study, the COF prepared from O-linked flexible 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine serves as an excellent absorbent for removing methylene blue from water. Our results demonstrate that COF is highly stable in water and functions as a robust adsorbent. Its adsorption isotherm is consistent with the Langmuir model and its adsorption kinetics follows a pseudo-second order model. Moreover, the COF was characterized using elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, solid-state ultraviolet–visible spectroscopy, and X-ray diffraction. It exhibited permanent porosity, a high specific surface area (279.5 m2·g–1), and was chemically and thermally stable. Photophysical studies revealed that the COF exhibits a low bandgap energy value of 3.07 eV, indicating its semiconducting nature.

Preparation and characterization of a novel ACF-TpPa-1 composite for dye adsorption

“…These illustrates the broad prospects of COF adsorbed dye materials. 25,26,[28][29][30][31][32][33] However, in the application of COF adsorption materials, powdered crystalline materials can cause many problems, such as recycling and pipeline clogging, which results in the deterioration of separation ability, limiting the extent of their practical application. Therefore, the researchers often process the powder into a thin film or other molded body through the method of material compounding to facilitate the application of COF materials.…”

From coordination polymer to carbon nanotube: Preparation, characterization and rapid adsorption capacity toward organic pollutants

“…Nowadays, dye contaminants in water have become a potential risk to both human health and ecological systems. 27–29 At present, a number of methods such as photocatalytic degradation, sonochemical degradation, Fenton-based oxidation, and ozonation have been developed to remove dyes from wastewater. 30–33 However, the cost of the above techniques is high, mainly due to the fact that they cannot be reused.…”

A New Squaraine‐Linked Triazinyl‐Based Covalent Organic Frameworks: Preparation, Characterization and Application for Sensitive and Selective Determination of Fe3+ Cations

“…COFs are linked by strong covalent bonds, such as B−O, C=N, C−N, B−N, and N=N bond linkages, which make them more stable and lower in density. Due to their remarkable properties, COFs present the potential in many specific functional applications, including gas storage and separation,[4] heterogeneous catalyst, photocatalysis, dye adsorption, optoelectricity, fluorescence detection, drug delivery, separation analysis, electric analysis, power storage, detection and adsorption of radioactive substances, and so on. At present, there are more and more functional COFs about fluorescence detection were reported.…”