Construction of Stable Magnetic Vinylene-Linked Covalent Organic Frameworks for Efficient Extraction of Benzimidazole Fungicides

Abstract

Covalent organic frameworks (COFs) have attracted impressive interest in separation on aqueous media. Herein, we integrated the stable vinylene-linked COFs with magnetic nanosphere via the monomer-mediated in situ growth strategy to construct a crystalline Fe3O4@v-COF composite for enrichment and determination of benzimidazole fungicides (BZDs) from complex sample matrices. The Fe3O4@v-COF has a crystalline assembly, high surface area, porous character together with a well-defined core–shell structure, and serves as progressive pretreatment materials for magnetic solid phase extraction (MSPE) of BZDs. Adsorption mechanism studies revealed that the extended conjugated system and numerous polar cyan groups on v-COF provides abundant π–π and multiple hydrogen bonding sites, which are conducive to interact with BZDs collaboratively. Fe3O4@v-COF also displayed enrichment effects to various polar pollutions with conjugated structures and hydrogen-bonding sites. Fe3O4@v-COF-based MSPE-high-performance liquid chromatography exhibited the low limit of detection, wide linearity, and good precision. Moreover, Fe3O4@v-COF showed better stability, enhanced extraction performance, and more sustainable reusability in comparison with its imine-linked counterpart. This work proposes a feasible strategy on constructing the crystalline stable magnetic vinylene-linked COF composite for the determination of trace contaminants in complex food matrices.

Facile Preparation of Magnetic COF-on-COF for Rapid Adsorption and Determination of Sulforaphane from Cruciferous Vegetables

“…The wide scan spectra (Figure 4a) of the MB-COFs-4 displayed four strong peaks at binding energies of 712.3, 531.4, 399.0, and 284.8 eV, which belonged to Fe 2p, O 1s, N 1s, and C 1s, respectively. The C 1s spectrum (Figure 4b) can be divided into three peaks, which are assigned to the π-π satellite (289.6 eV), C-N (286.7 eV), and C-C (284.8 eV), respectively [33]. In the N 1s spectrum (Figure 4c), the peaks located at 400.5 and 399.0 eV can be attributed to the C-N and C=N, respectively [17].…”

Iron Oxide Nanomaterials at Interfaces for Sustainable Environmental Applications

“…The surface activity of magnetic NPs proves to be a remarkable driving force for facilitated extraction from the aqueous bulk. Extraction of different species from the aqueous bulk is mainly reported for water soluble magnetic NPs where such NPs need to incorporate into the aqueous bulk in order to accomplish the extraction. , In contrast, surface active magnetic NPs perform this action while adsorbing at the air–aqueous interface, thus making them highly selective in performing a specific extraction. , …”

Magnetic Covalent Organic Framework for Efficient Solid-Phase Extraction of Uranium for on-Site Determination by Portable X-ray Fluorescence Spectrometry

“…Covalent organic frameworks (COFs), an emerging class of porous organic frameworks, have been barged to the forefront of adsorbent materials, owing to their exceptional physical and chemical stability, abundant well-proportioned pores, large specific surface areas, rich functional groups, tunable chemical properties, and high adsorption capacity . The combination of COFs and Fe 3 O 4 can solve the problem of inconvenient separation from solution caused by the low density of COFs, so as to reduce the mass loss of COFs and expand its application in the field of separation and enrichment. − So far as we know, the utilization of magnetic COF as an adsorbent has not been reported for the enrichment and determination of uranyl ions by XRF.…”