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A novel magnetic copper-based metal organic framework (M-MOF-199) has been successfully prepared using Fe 3 O 4 –graphene oxide (GO) nanocomposite for solid phase extraction of five triazole pesticides from environment water samples. High-performance liquid chromatography coupled with tandem mass spectrometry was used for sample quantification and determination. The results suggest that Fe 4 O 3 –GO is a thin single-layer structure anchoring Fe 3 O 4 and M-MOF-199 is coated on its surface. Under the optimized conditions, the limits of detection of the triazole pesticides are 0.05–0.1 (S/N = 3) with correlation coefficients larger than 0.992. The recoveries in spiked water samples are 72.3%–91.53% with relative standard deviations ranging from 1.5% to 9.1%. Furthermore, the results show that M-MOF-199 is a promising hybrid adsorbent for magnetic dispersive solid phase extraction and removal of triazole pesticides from environmental water samples. [ABSTRACT FROM AUTHOR]

A novel magnetic copper-based metal–organic framework (M-MOF) was prepared using a Fe 4 O 3 –graphene oxide (GO)–β-cyclodextrin (β-CD) nanocomposite as the magnetic core and support, and used for adsorption and removal of neonicotinoid insecticide pollutants from aqueous solution. M-MOF characterization suggested that 1 Fe 4 O 3 –GO–β-CD consisted of a thin single layer with anchored Fe 3 O 4 . The M-MOF was coated on the Fe 4 O 3 –GO–β-CD surface. The M-MOF had a large Brunauer–Emmett–Teller surface area (250.33 m 2 g −1) and high super-paramagnetism with saturation magnetization of 10.47 emu g −1 . Adsorption model analysis showed that the equilibrium data for thiacloprid fitted Langmuir monolayer adsorption and the other insecticides tested showed Freundlich bimolecular layer adsorption. The results show that M-MOF is a promising hybrid adsorbent for rapid removal of neonicotinoid insecticide pollutants from environmental waters. [ABSTRACT FROM AUTHOR]

The mediation effect of reduced graphene oxide (rGO) on the oxidative transformation of 1,4-hydroquinone (H 2 Q) to 1,4-benzoquinone (BQ) in aqueous solution was investigated using a batch method and electron paramagnetic resonance. The results showed that the autoxidation of H 2 Q was spin-restricted and extremely slow in acidic and neutral pH range, but this process can be dramatically accelerated when rGO was added. In the presence of 33.3 mg L −1 rGO, more than 76.0% of H 2 Q was oxidized to BQ within 36 h. The enhancement effects of rGO were attributed to the combined contribution of the high chemical reactivity of graphenic edges and defects on rGO and the high electron conductivity of graphene basal surface of rGO. It is proposed that dissolved oxygen reacted with graphenic edges and defects of rGO to produce surface-bound oxygen intermediates, which capture H atoms from the phenolic hydroxyl groups of H 2 Q and facilitate the generation of semiquinone radical (SQ − ). The generated SQ − continued to transfer an electron to molecular oxygen to yield superoxide radical (O 2 − ) and BQ. As a chain-carrying radical, O 2 − further reacted with H 2 Q to produce SQ − and H 2 O 2 . [ABSTRACT FROM AUTHOR]