Zhou Xiaoli, Lei Wenjuan, Qin Xiaohuan, Lai Xiaofen, Hu Kun, Zhao Shulin
State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education of China), Collaborative Innovation Center for Guangxi Ethnic Medicine, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin, 541004, P. R. China.
Anal Bioanal Chem. 2025 Feb;417(4):675-685. doi: 10.1007/s00216-024-05687-x. Epub 2024 Dec 9.
Simultaneous removal and identification of trace-level cationic dye pollutants from water is both important and challenging owing to their highly polar and complex sample matrices. In this study, three covalent organic frameworks (COFs) were synthesized using 2, 4, 6-triformylphloroglucinol with ethidium bromide (EB) containing positively charged groups, 3, 5-diaminobenzoic acid (DABA) containing negatively charged groups, and p-phenylenediamine (Pa) lacking charged groups. These were named EB-COFs, TpPa-1, and DP-COFs, respectively, and were employed as adsorbents for the extraction and identification of cationic dyes. The adsorption performance of the three COFs toward methylene blue (MB) and crystal violet (CV) was investigated. By incorporating carboxyl groups into DP-COFs, the surface chemistry of the adsorbent was effectively tailored, enabling complete exploitation of selective cationic sites. This facilitated dynamic interactions with cationic dyes through multiple adsorption mechanisms, including electrostatic, π-π, and H-bonding interactions. DP-COFs exhibited high adsorption capacities for MB and CV, achieving 383 and 326 mg g, respectively. The adsorption behavior was further analyzed using adsorption isothermals, kinetics, and thermodynamics. Moreover, DP-COFs were employed as a matrix in laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) to adsorb and directly identify both cationic dyes without the need for an elution process. This approach demonstrated high sensitivity, high reproducibility, low background interference, and excellent salt tolerance. The limits of detection for MB and CV were 0.12 and 0.04 ng mL, respectively, representing improvements of 166-fold and 225-fold compared with using DP-COFs solely as a matrix. Recovery rates of both dyes in spiked industrial wastewater and lake water samples ranged from 81.4 to111.1% with RSDs of 1.9-6.3%. These results highlight the high reliability of the proposed method.
由于水中痕量阳离子染料污染物具有高度极性且样品基质复杂，同时去除和鉴定这些污染物既重要又具有挑战性。在本研究中，使用2,4,6-三甲基间苯三酚分别与含有带正电荷基团的溴化乙锭（EB）、含有带负电荷基团的3,5-二氨基苯甲酸（DABA）以及不含电荷基团的对苯二胺（Pa）合成了三种共价有机框架（COF）。它们分别被命名为EB-COF、TpPa-1和DP-COF，并用作吸附剂用于阳离子染料的萃取和鉴定。研究了这三种COF对亚甲基蓝（MB）和结晶紫（CV）的吸附性能。通过将羧基引入DP-COF中，有效地调整了吸附剂的表面化学性质，从而能够充分利用选择性阳离子位点。这通过多种吸附机制促进了与阳离子染料的动态相互作用，包括静电、π-π和氢键相互作用。DP-COF对MB和CV表现出高吸附容量，分别达到383和326 mg g。使用吸附等温线、动力学和热力学对吸附行为进行了进一步分析。此外，DP-COF被用作激光解吸/电离飞行时间质谱（LDI-TOF MS）中的基质，用于吸附并直接鉴定两种阳离子染料，无需洗脱过程。该方法具有高灵敏度、高重现性、低背景干扰和优异的耐盐性。MB和CV的检测限分别为0.12和0.04 ng mL，与仅将DP-COF用作基质相比，分别提高了166倍和225倍。加标工业废水和湖水样品中两种染料的回收率在81.4%至111.1%之间，相对标准偏差为1.9 - 6.3%。这些结果突出了所提出方法的高可靠性。
