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Research on functionalized covalent organic framework (COF) materials with good hydrophilic characteristics is significant on account of their application in the removal of dyes in wastewater. In this work, two anionic COF materials (TFPB-Pa-SO3H COF and TFPB-BDSA COF) were successfully synthesized with sulfonated modification as dyestuff sorbents to be used for the adsorption of cationic dyes. The two prepared COF materials exhibited predominant hydrophilicity with lower water contact angles (35° and 27°) than reported COF materials. The sulfonated groups on the COFs can efficiently adsorb cationic dyes via electrostatic interaction, which can moderately ameliorate their adsorptive capacity toward hydrosoluble dyes. TFPB-Pa-SO3H COF and TFPB-BDSA COF showed superfast adsorption equilibrium with methylene blue (1 and 2 min) and high adsorption uptakes of crystal violet (1559 and 1288 mg g−1), which manifested that the adsorption rate may be closely related to the solubilities of the host COF materials as well as the guest dye molecule in aqueous solution. Meanwhile, the adsorption stability between the COF materials and dye molecule adsorbed on the COF skeleton accounted for the highly effective adsorption of the target dye in a large quantity. In addition, TFPB-Pa-SO3H COF as an adsorbing material was successfully applied for the removal of dye molecules in real water samples. [ABSTRACT FROM AUTHOR]

Rationally designing porous materials with excellent hydrophilic performance for the selective removal of contaminants from wastewaters before discharge into the environment is highly desirable but still faces challenges. Herein, to address the shuttle issue, a hydrophilic covalent organic framework (BTA-BDSA-COF) was synthesized by introducing multi-sulfonated groups into a covalent framework structure and its potential applications in cationic dye capture have been evaluated in detail. Topological modulation and structural characteristics reveal the following: (1) a regular single-pore (SP) framework of BTA-BDSA-COF is constructed which is distinguishable from most reported COFs, with a condensation of D2h symmetry and ditopic linear diamine building blocks. (2) BTA-BDSA-COF undergoing excellent hydrophilicity outperforms other studied COFs functioned with sulfonated groups. Furthermore, dye sorption selectivity and kinetic studies clearly state the following: (1) the hydrophilic feature of anionic BTA-BDSA-COF is a significant driving force to ameliorate the adsorption ability of cationic dyes. (2) The degree of match between the size of the BTA-BDSA-COF pore aperture and the volume of dye molecule is intimately related to the dye adsorption properties. Therefore, BTA-BDSA-COF exhibits an impressive MLB adsorptive capacity of 1280 mg g−1 and a quick adsorption equilibrium of 30 min, owing to the moderately hydrophilic pore environment of BTA-BDSA-COF. Successful application in real water samples suggests that BTA-BDSA-COF with moderate hydrophilicity would be a promising adsorbent candidate for practical cationic dye capture. [ABSTRACT FROM AUTHOR]