Attractive environmentally friendly magnetic metal-organic framework (MOF) nanocomposite GO@Fe 3 O 4 -COOH@NH 2 -MIL-101(Fe) was synthesized by a solvothermal method and characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, Brunauer– Emmett–Teller, and vibrating sample magnetometer, and used as an effective adsorbent for the removal of orange G from aqueous solution. The various operating parameters that effect the adsorption process, such as adsorbent dosage (0.01–0.2 g), pH (1.0–10.0), initial concentration (50–400 mg L –1 ), and temperature (298.15–318.15 K) were studied. The percent removal of orange G increases with the increment of the adsorbent dosage and decrease of the initial concentration, and the optimum pH is 6.0. The Redlich–Peterson model can be favorably applied to describe the adsorption equilibrium data, indicating that the surfaces of GO@Fe 3 O 4 -COOH@NH 2 -MIL-101(Fe) nanocomposite for the orange G adsorption are made up of homogeneous adsorption patches. The adsorption kinetics indicate that the adsorption process of GO@Fe 3 O 4 -COOH@NH 2 -MIL-101(Fe) toward orange G obeys the pseudo-second-order model and the activation energy is 16.5 kJ mol –1 . Thermodynamic parameters, ΔH = 39.81 kJ mol –1 , ΔS = –46.80 J mol –1 K –1 , and ΔG < 0, exhibit that the adsorption is exothermic and spontaneous. The maximum adsorption capacity of orange G onto GO@Fe 3 O 4 -COOH@NH 2 -MIL-101(Fe) nanocomposite is 128.8 mg g –1 . Therefore, magnetic GO@ Fe 3 O 4 -COOH@NH 2 -MIL-101(Fe) nanocomposite can be employed as an environmentally friendly and efficient adsorbent for the orange G removal from wastewater.
Zi-Yu Li,Jia-Hui Zhu,Jie Zhao,Xiao-Shuai Yang,Yu-Shen Liu,Ting Cheng,Yan-Xin Chen,Shu-Yang Sun,Lu-Liang Wang
Magnetic solid-phase extraction (MSPE) technology for tetracycline (TCC) was developed by employing the novel and pre-designed Fe 3 O 4 –COOH@hydrogen-bonded organic frameworks (HOFs) adsorbents in complex food samples. The HOF shell was grown onto the Fe 3 O 4 –COOH core by in-situ self-assembled method. The excellent MSPE performances with less solvent, less adsorbent and time consumption were derived from the hydrogen bonding, π-π and hydrophobic interactions between HOF shell and TCC. Combined with HPLC analysis, Fe 3 O 4 @ HOFs adsorbent reduced matrix effects and the established MSPE-HPLC method for TCC gave the linearity of 0.001–6 μg mL −1 with the limit of detection 0.0003 μg mL −1 . The recoveries in pure milk, canned yellow peach and carrot were 82.4–103.7 %. The method provided a simple, efficient and dependable alternative to monitor trace TCC antibiotics in food or environmental samples.
Mengmeng Zhang,Wei Zhou,Qingqing Wang,Ning Wang,Xin Wang,Youping Liu,Xin Di
In this work, a novel water compatible core–shell magnetic molecularly imprinted nanocomposite (Fe3O4–COOH@MIPs) was synthesized in an acetonitrile–water reaction system by adopting carboxyl group-functionalized Fe3O4 nanoparticles as the magnetic core, olaquindox as the template molecule and acrylamide as the functional monomer. The resulting Fe3O4–COOH@MIPs was characterized and applied as an adsorbent for magnetic solid-phase extraction (MSPE) of three quinoline-1,4-dioxides (QdNOs). The Fe3O4–COOH@MIPs possessed strong magnetic responsiveness, fast adsorption equilibrium rate (equilibrium within 5 min) and excellent selectivity. By coupling Fe3O4–COOH@MIPs based MSPE with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), good linearity (R2 ≥ 0.9985) and low limits of detection (0.83–5.0 ng L−1) for QdNOs were obtained. Finally, the proposed method was applied to determine trace QdNOs in environmental water samples, and the recoveries were in the range of 68.08–99.88% with RSD less than 12.5%.
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