Synthesis,characterization and properties of multifunctional poly(arylene ether nitriles) (PEN)/CNTs/Fe3O4 nanocomposites

In this study, a novel multifunctional poly(arylene ether nitriles)(PEN)/carbon nanotubes/Fe₃O₄ nanocomposite with high tensile strength, magnetic, and electrical properties was investigated. First, we synthesized the monodisperse Fe₃O₄ nanoparticles on the surface of the multiwalled carbon nanotubes and then the hybrid material was compounded with PEN through the solution‐casting method. The SEM and TEM images indicated that the monodisperse Fe₃O₄ nanoparticles, with the diameters of 70∼80 nm, were self‐assembled along CNTs via the covalent bond method, which was confirmed by FTIR and XRD. The results of tensile properties showed that the tensile strength and modulus reached their highest values at the CNTs/Fe₃O₄ loading content of 1 wt % and both were greatly enhanced after heat treatment. Electrical conductivity of the polymer was dramatically enhanced at the low loading level of CNTs/Fe₃O₄; the electrical percolation of was in the range of 5∼8 wt % of CNTs/Fe₃O₄. The magnetic study showed that the saturation magnetization (M_s) of PEN/CNTs/Fe₃O₄ nanocomposites increased with the increase of CNTs/Fe₃O₄ loading content, and the coercive force (H_c) of the nanocomposite was independent of the CNTs/Fe₃O₄ content. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

3‐D graphene‐supported mesoporous SiO2@Fe3O4 composites for the analysis of pesticides in aqueous samples by magnetic solid‐phase extraction with high‐performance liquid chromatography

Three‐dimensional graphene‐supported mesoporous silica@Fe₃O₄ composites (mSiO₂@Fe₃O₄‐G) were prepared by modifying mesoporous SiO₂‐coated Fe₃O₄ onto hydrophobic graphene nanosheets through a simple adsorption co‐condensation method. The obtained composites possess unique properties of large surface area (332.9 m²/g), pore volume (0.68 cm³/g), highly open pore structure with uniform pore size (31.1 nm), as well as good magnetic separation properties. The adsorbent (mSiO₂@Fe₃O₄‐G) was used for the magnetic solid‐phase extraction of seven pesticides with benzene rings in different aqueous samples before high‐performance liquid chromatography. The main parameters affecting the extraction such as adsorbent amount, volume of elution solvent, time of extraction and desorption, salt effect, oscillation rate were investigated. Under the optimal conditions, this method provided low limits of detection (S/N = 3, 0.525–3.30 μg/L) and good linearity (5.0–1000 μg/L, R² > 0.9954). Method validation proved the feasibility of the developed adsorbent, which has a high extraction efficiency and excellent enhancement performance for pesticides in this study. The proposed method was successfully applied to real aqueous samples, and satisfactory recoveries ranging from 77.5 to 113.6% with relative standard deviations within 9.7% were obtained.     

Graphene‐Fe3O4 as a magnetic solid‐phase extraction sorbent coupled to capillary electrophoresis for the determination of sulfonamides in milk

Graphene‐Fe₃O₄ nanoparticles were prepared using one‐step solvothermal method and characterized by X‐ray diffraction, FTIR spectroscopy, scanning electron microscopy, and vibrating sample magnetometry. The results demonstrated that Fe₃O₄ nanoparticles were homogeneously anchored on graphene nanosheets. The as‐synthesized graphene‐Fe₃O₄ nanoparticles were employed as sorbent for magnetic solid‐phase extraction of sulfonamides in milk prior to capillary electrophoresis analysis. The optimal capillary electrophoresis conditions were as follows: 60 mmol/L Na₂HPO₄ containing 2 mmol/L ethylenediaminetetraacetic acid disodium salt and 24% v/v methanol as running buffer, separation voltage of 14 kV, and detection wavelength of 270 nm. The parameters affecting extraction efficiency including desorption solution, the amount of graphene‐Fe₃O₄ nanoparticles, extraction time, and sample pH were investigated in detail. Under the optimal conditions, good linearity (5–200 μg/L) with correlation coefficients ≥0.9910 was obtained. The limits of detection were 0.89–2.31 μg/L. The relative standard deviations for intraday and interday analyses were 4.9–8.5 and 4.0–9.0%, respectively. The proposed method was successfully applied to the analysis of sulfonamides in milk samples with recoveries ranging from 62.7 to 104.8% and relative standard deviations less than 10.2%.     

Graphene grafted silica‐coated Fe3O4 nanocomposite as absorbent for enrichment of carbamates from cucumbers and pears prior to HPLC

In this paper, a novel graphene (G) grafted silica‐coated Fe₃O₄ nanocomposite was fabricated by the chemical bonding of G onto the surface of silica‐coated Fe₃O₄ nanoparticles. Some carbamates (metolcarb, carbaryl, pirimicarb, and diethofencarb) in cucumber and pear samples were enriched by this nanocomposite prior to their determination by HPLC with UV detection. Experimental parameters that may affect the extraction efficiency were investigated. Under the optimum conditions, a linear response was achieved in the concentration range of 0.5–100.0 ng/g for metolcarb, carbaryl, and diethofencarb, and 1.0–100 ng/g for pirimicarb with the correlation coefficients (r) ranging from 0.9956 to 0.9984. The LOD (S/N = 3) of the method were found to be in the range from 0.08 to 0.2 ng/g. The RSDs were in the range from 2.4 to 5.8%. The results indicated that the G grafted silica‐coated Fe₃O₄ nanocomposite was stable and efficient for magnetic SPE and has a great application potential for the preconcentration of other organic pollutants from real samples.     

A Novel Biomimetic Hydrogen Peroxide Biosensor Based on Pt Flowers‐decorated Fe3O4/Graphene Nanocomposite

A sensitive and selective amperometric H₂O₂ biosensor was obtained by utilizing the electrodeposition of Pt flowers on iron oxide‐reduced graphene oxide (Fe₃O₄/rGO) nanocomposite modified glassy carbon electrode (GCE). The morphology of Fe₃O₄/rGO and Pt/Fe₃O₄/rGO was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The step‐wise modification and the electrochemical characteristics of the resulting biosensor were characterized by cyclic voltammetry (CV) and chronoamperometry methods. Thanks to the fast electron transfer at the Pt/Fe₃O₄/rGO electrode interface, the developed biosensor exhibits a fast and linear amperometric response upon H₂O₂. The linear range of Pt/Fe₃O₄/rGO is 0.1∼2.4 mM (R²=0.998), with a sensitivity of 6.875 μA/mM and a detection limit of 1.58 μM (S/N=3). In addition, the prepared biosensor also provides good anti‐interferent ability and long‐term stability due to the favorable biocompatibility of the electrode interface. The proposed sensor will become a reliable and effective tool for monitoring and sensing the H₂O₂ in complicate environment.     

Development of novel magnetic solid-phase extraction sorbent based on Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/carbon nanosphere/polypyrrole composite and their application to the enrichment of polycyclic aromatic hydrocarbons from water samples prior to GC–FID analysis

We describe a magnetic nanocomposite that consists of Fe₃O₄/carbon nanosphere/polypyrrole (Fe₃O₄/CNS/PPy). The synthesized nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The nanocomposite was successfully applied to extract of the polycyclic aromatic hydrocarbons (PAHs) from water samples. Compared to Fe₃O₄/PPy, the Fe₃O₄/CNS/PPy nanocomposite exhibits improved properties in terms of extraction. The amount of adsorbent, salt effect, extraction time, desorption time, type, and the volume of desorption solvent were optimized. Following the desorption of the extracted analytes, the PAHs (i.e., naphthalene, 2-methylnaphthalene, 2-bromonaphthalene, fluorene, and anthracene) were quantified by gas chromatography–flame ionization detector. The PAHs can be determined in 0.05–100.00 ng mL^?1 concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.01 to 0.05 ng mL^?1. The repeatability of the method was investigated with relative standard deviations of lower than 9.9% (n = 5). Also, the recoveries from spiked real water samples were in the range of 88.9–99.0%. The results indicate that the novel material can be successfully applied for the extraction and analysis of PAHs from water samples.     

Hydrothermal development of magnetic-hydrochar nanocomposite from pineapple leaves and its performance as an adsorbent for the uptake of Mn2+ and reuse of the metal loaded adsorbent in latent fingerprint

Manganese is one of the heavy metals that is a major environmental concern when present in large amount. Manganese is discarded into water systems by numerous industries, including mining, batteries and electroplating etc. Pineapple leaves were applied as a biomass source to produce a magnetic hydrothermal treated hydochar nanocomposite; Fe₃O₄-HC. The BET surface area of Fe₂O₃-HC nanocomposite was 21.27 m²/g. Batch adsorption experiments revealed that the uptake of Mn²⁺ fit well in the pseudo second kinetics model, while the adsorption isotherm best fit the Freundlich model, with a maximum adsorption capacity of 2.99 mg/g at 25 °C and a pH of 5. The obtained thermodynamic parameters demonstrated that Mn²⁺ ion adsorption using the Fe₂O₃-HC nanocomposite was endothermic and nonspontaneous. Additionally, Fe₂O₃-HC nanocomposite demonstrated to be highly selective towards Mn²⁺ ions in the presence of other ions. The removal percentage of Mn²⁺ from a real water sample spiked with 50 mg/L Mn²⁺ was reported to be 53.2%. The spent adsorbent was then used to detect latent fingerprints, which revealed that Mn²⁺-Fe₂O₃-HC nanocomposite generated better and clear latent fingerprints than Fe₂O₃-HC nanocomposite.     

Selective separation and determination of the synthetic colorants in beverages by magnetic solid‐phase dispersion extraction based on a Fe3O4/reduced graphene oxide nanocomposite followed by high‐performance liquid chromatography with diode array detection

A facile adsorbent, a nanocomposite of Fe₃O₄ and reduced graphene oxide, was fabricated for the selective separation and enrichment of synthetic aromatic azo colorants by magnetic solid‐phase dispersion extraction. The nanocomposite was synthesized in a one‐step reduction reaction and characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X‐ray diffraction and Brunauer–Emmett–Teller analysis. The colorants in beverages were quickly adsorbed onto the surface of the nanocomposite with strong π–π interactions between colorants and reduced graphene oxide, and separated with the assistance of an external magnetic field. Moreover, the four colorants in beverages were detected at different wavelengths by high performance liquid chromatography with diode array detection. A linear dependence of peak area was obtained over 0.05–10 μg/mL with the limits of detection of 10.02, 11.90, 10.41, 15.91 ng/mL for tartrazine, allure red, amaranth, and new coccine, respectively (signal to noise = 3). The recoveries for the spiked colorants were in the range of 88.95–95.89% with the relative standard deviation less than 2.66%. The results indicated that the nanocomposite of Fe₃O₄ and reduced graphene oxide could be used as an excellent selective adsorbent for aromatic compounds and has potential applications in sample pretreatment.     

Dual Amplified Electrochemical Immunosensor for Hepatitis B Virus Surface Antigen Detection Using Hemin/G‐Quadruplex Immobilized onto Fe3O4‐AuNPs or (Hemin‐Amino‐rGO‐Au) Nanohybrid

A sensitive electrochemical immunosensor for Hepatitis B virus surface antigen (HBsAg) detection was fabricated based on hemin/G‐quadruplex interlaced onto Fe₃O₄‐AuNPs or hemin ‐amino‐reduced graphene oxide nanocomposite (H‐amino‐rGO‐Au). G‐quadruplex DNAzyme, which is composed of hemin and guanine‐rich nucleic acid, is an effective signal amplified tool for its outstanding peroxidase activity and Fe₃O₄‐AuNPs or (H‐amino‐rGO‐Au) nanocomposites with quasi‐enzyme activity provide appropriate support for the immobilization of hemin/G‐quadruplex. The target protein was sandwiched between the primary antibody immobilized on the GO and secondary antibody immobilized on the Fe₃O₄‐AuNPs or (H‐amino‐rGO‐Au) nanocomposites and glutaraldehyde was used as linking agent for the immobilization of primary antibody on the surface of GO. Both Fe₃O₄‐AuNPs and H‐amino‐rGO‐Au nanocomposite and also hemin/G‐quadruplex can cooperate the electrocatalytic reduction of H₂O₂ in the presence of methylene blue as mediator. The proposed immunosensor has a wide linear dynamic range of 0.1 pg/ml to 300 pg/ml with a detection limit of 60 fg/ml when Fe₃O₄‐AuNPs was used for immobilization of hemin/G‐quadruplex, while the dynamic range and DL were 0. 1–1000 pg/mL and 10 fg/mL, respectively in the presence of H‐amino‐rGO‐ Au nanocomposite as platform for immobilizing of hemin/G‐quadruplex. The proposed immunosensor was also used for analysis of HBsAg in spiked human serum samples with satisfactory results.     

Magnetic solid-phase extraction based on Fe3O4/graphene oxide nanoparticles for the determination of malachite green and crystal violet in environmental water samples by HPLC

This work describes a magnetic Fe₃O₄/graphene oxide (GO)-based solid-phase extraction (MSPE) technique for high performance liquid chromatography (HPLC) detection of malachite green (MG) and crystal violet (CV) in environmental water samples. Fe₃O₄/ GO magnetic nanoparticles were synthesised by a chemical co-precipitation method and characterised by scanning electron micrograph, transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and surface area analyser. The prepared Fe₃O₄/GO magnetic nanoparticles were used as the adsorbents of MSPE for MG and CV. By coupling with HPLC, a sensitive and cost-effective method for simultaneous determination of MG and CV was developed. The important parameters including the amount of Fe₃O₄/GO, pH of the sample solution, extraction time, salt effect, the type and volume of desorption solvent were investigated in detail. Under optimised conditions, the calibration curves were linear in the concentration range of 0.5–200 μg L^?1, and the limits of detection were 0.091 and 0.12 μg L^?1 for MG and CV, respectively. Finally, the established MSPE-HPLC method was successfully applied to determine MG and CV in environmental water samples with the recoveries ranging from 91.5% to116.7%.     

Magnetic solid-phase extraction of warfarin and gemfibrozil in biological samples using polydopamine-coated magnetic nanoparticles via core-shell nanostructure

Herein, polydopamine-coated Fe₃O₄ spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe₃O₄) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe₃O₄. The prepared polydopamine-coated Fe₃O₄ spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1–200.0 μg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026–0.055 μg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089–0.185 μg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%–3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.     

Green synthesis of Ag/Fe3O4 nanoparticles using Mentha extract: Preparation,characterization and investigation of its anti-human lung cancer application

In this study, silver nanoparticles (Ag NPs) were decorated on the surface of magnetic nanoparticles in an eco-friendly pathway applying Mentha extract as reducing/stabilizing agent. The morphological and physicochemical features of the prepared Ag/Fe₃O₄nanocomposite were determined using several advanced techniques. Hence, our protocol is green and advantageous in terms of- i) biochemical modified biocompatible nanocomposite; ii) nanomaterial providing high surface area and larger number reactive sites; iii) very simplistic synthetic procedure; vi) very low load of metal in the composite and v) high yield in short time. In the medicinal part, the anticancer properties of Ag/Fe₃O₄ nanocomposite against lung cancer cell lines were determined. The free radical for the antioxidant effects was DPPH. The IC₅₀ of Ag/Fe₃O₄ nanocomposite was 200 µg/ml in the antioxidant test. The IC₅₀ of the Ag/Fe₃O₄ nanocomposite were 183, 176, 169, and 125 µg/mL against lung cancer (NCI-H661, NCI-H1975, NCI-H1573, and NCI-H1563) cell lines, respectively. In addition, the current study offer that Ag/Fe₃O₄ nanocomposite could be a new potential adjuvant chemopreventive and chemotherapeutic agent against cytotoxic cells.     

Decyl‐perfluorinated magnetic mesoporous microspheres for extraction and analysis perfluorinated compounds in water using ultrahigh‐performance liquid chromatography–mass spectrometry

In this work, the interior‐walls decyl‐perfluorinated functionalized magnetic mesoporous microspheres (F₁₇–Fe₃O₄@mSiO₂) were synthesized for the first time, and applied as adsorbents to extract and concentrate perfluorinated compounds (PFCs) from water samples. The fluorous functionalized interior pore‐walls contributed to the high‐selective preconcentration of PFCs due to fluorous affinity; and abundant silanol groups on the exterior surface of microspheres contributed to the good dispersibility in water sample. Four kinds of PFCs were selected as model analytes, including perfluorooctanoic acid, perfluorononanoic acid, perfluorododecanoic acid, and perfluorooctane sulphonate. In addition, UHPLC‐ESI/MS/MS was introduced to the fast and sensitive detection of the analytes after sample pretreatment. Important parameters of the extraction procedure were optimized, including salinity, eluting solvent, the amount of F₁₇–Fe₃O₄@mSiO₂ microspheres, and extraction time. The optimized procedure took only 10 min to extract analytes with high recoveries and merely 800‐μL acetonitrile to elute analytes from the magnetic adsorbents. Validation experiments showed good linearity (0.994–0.998), precision (2.6–7.6%), high recovery (93.4–105.7%) of the proposed method, and the limits of detection were from 0.008 to 0.125 μg/L. The F₁₇–Fe₃O₄@mSiO₂ magnetic microspheres have the advantages of great dispersibility in aqueous solution, high specificity of extraction, large surface area, and efficient separation ability. The results showed that the proposed method based on F₁₇–Fe₃O₄@mSiO₂ microspheres is a simple, fast, and sensitive tool for the analysis of PFCs in water sample.     

Magnetic Nitrogen-Doped Porous Carbon Nanocomposite for Pb(II) Adsorption from Aqueous Solution

We report in the present study the in situ formation of magnetic nanoparticles (Fe₃O₄ or Fe) within porous N-doped carbon (Fe₃O₄/N@C) via simple impregnation, polymerization, and calcination sequentially. The synthesized nanocomposite structural properties were investigated using different techniques showing its good construction. The formed nanocomposite showed a saturation magnetization (M_s) of 23.0 emu g⁻¹ due to the implanted magnetic nanoparticles and high surface area from the porous N-doped carbon. The nanocomposite was formed as graphite-type layers. The well-synthesized nanocomposite showed a high adsorption affinity toward Pb²⁺ toxic ions. The nanosorbent showed a maximum adsorption capacity of 250.0 mg/g toward the Pb²⁺ metallic ions at pH of 5.5, initial Pb²⁺ concentration of 180.0 mg/L, and room temperature. Due to its superparamagnetic characteristics, an external magnet was used for the fast separation of the nanocomposite. This enabled the study of the nanocomposite reusability toward Pb²⁺ ions, showing good chemical stability even after six cycles. Subsequently, Fe₃O₄/N@C nanocomposite was shown to have excellent efficiency for the removal of toxic Pb²⁺ ions from water.     

Simultaneous determination of ten organophosphate pesticide residues in fruits by gas chromatography coupled with magnetic separation

In this study, γ‐Fe₂O₃/chitosan magnetic microspheres were synthesized and evaluated by X‐ray diffraction, SEM, thermogravimetric analysis, and static and kinetic adsorption experiments. Results showed that the magnetic microspheres exhibited good adsorption ability, and offered fast kinetics for the adsorption of trichlorfon, methamidophos, malathion, methyl parathion, dimethoate, omethoate, phosphamidon, phorate, isocarbophos, and chlorpyrifos. Based on magnetic separation, a simple method of magnetic SPE coupled to GC for the simultaneous determination of ten trace organophosphate pesticide residues was developed. Under the optimal conditions, the enrichment factor for ten organophosphorus pesticides was 10.1–364.7 and linear range was 0.001–10.0 mg/L. The LOD (S/N = 3) of the method for the ten pesticides was 0.31–3.59 μg/kg. The RSD for three replicate extractions of spiked samples was between 2.5 and 6.3%. The pear and apple samples spiked with ten organophosphate pesticides at 20 and 200 μg/kg levels were extracted and determined by this method with good recoveries ranging from 79.9 to 98.7%. Moreover, the method has been successfully applied for the determination of the ten organophosphate pesticide residues in peach samples.     

Green supported Cu nanoparticles on modified Fe3O4 nanoparticles using thymbra spicata flower extract: Investigation of its antioxidant and the anti-human lung cancer properties

In recent days, the green synthesized nanomagnetic biocomposites have been evolved with tremendous potential as the future biological agents. This has encouraged us to design and synthesis of a novel Cu NPs supported Thyme flower extract modified magnetic nanomaterial (Fe₃O₄/Thyme-Cu). It was meticulously characterized using advanced analytical techniques like FT-IR, FESEM, TEM, EDX, VSM, XRD and ICP-OES. After the characterization, the synthesized Fe₃O₄/Thyme-Cu nanocomposite was engaged in biological assays like study of anti-oxidant properties by DPPH mediated free radical scavenging test using BHT as a reference molecule. Thereafter, on having a significant IC50 value in radical scavenging assay, we extended the bio-application of the desired nanocomposite in anticancer study of A549, Calu6 and H358 human lung cell lines in-vitro through MTT assay. They had very low cell viability and high anti-human lung cancer activities dose-dependently against A549, Calu6 and H358 cell lines without any cytotoxicity on the normal cell line (MRC-5). The IC50 of Fe₃O₄/Thyme-Cu nanocomposite was 124, 265, and 181 µg/mL against A549, Calu6 and H358 cell lines, respectively. Maybe significant anti-human lung cancer potentials of Fe₃O₄/Thyme-Cu nanocomposite against common lung cancer cell lines are related to their antioxidant activities. So, these results suggest that synthesized Fe₃O₄/Thyme-Cu nanocomposite as a chemotherapeutic nanomaterial have a suitable anticancer activity against lung cell lines.     

General Preparation of Heme Protein Functional Fe3O4@Au‐Nps Magnetic Nanocomposite for Sensitive Detection of Hydrogen Peroxide

Stable magnetic nanocomposite of gold nanoparticles (Au‐NPs) decorating Fe₃O₄ core was successfully synthesized by the linker of Boc‐L‐cysteine. Transmission electron microscope (TEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammograms (CV) were performed to characterize the as‐prepared Fe₃O₄@Au‐Nps. The results indicated that Au‐Nps dispersed homogeneously around Fe₃O₄ with the ratio of Au to Fe₃O₄ nanoparticles as 5–10/1 and the apparent electrochemical area as 0.121 cm². After self‐assembly of hemoglobin (Hb) on Fe₃O₄@Au‐Nps by electrostatic interaction, a hydrogen peroxide biosensor was developed. The Fe₃O₄@Au‐Nps/Hb modified GCE exhibited fast direct electron transfer between heme center and electrode surface with the heterogeneous electron transfer rate constant (Ks ) of 3.35 s⁻¹. Importantly, it showed excellent electrocatalytic activity towards hydrogen peroxide reduction with low detection limit of 0.133 μM (S /D =3) and high sensitivity of 0.163 μA μM⁻¹, respectively. At the concentration evaluated, the interfering species of glucose, dopamine, uric acid and ascorbic acid did not affect the determination of hydrogen peroxide. These results demonstrated that the introduction of Au‐Nps on Fe₃O₄ not only stabilized the immobilized enzyme but also provided large surface area, fast electron transfer and excellent biocompatibility. This facile nanoassembly protocol can be extended to immobilize various enzymes, proteins and biomolecules to develop robust biosensors.     

Room Temperature Synthesis and Photocatalytic Activity of Magnetically Recoverable Fe3O4/BiOCl Nanocomposite Photocatalysts

Magnetically recoverable Fe₃O₄/BiOCl nanocomposite photocatalysts were fabricated by a simple chemical coprecipitation method at room temperature. The amount of Fe₃O₄ incorporated into BiOCl was varied from 0 to 20 wt%. The as-synthesized samples were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, UV–Vis diffuse reflectance spectroscopy, and vibrating sample magnetometer. The obtained results show that the as-synthesized samples mainly contain both crystalline phases (Fe₃O₄ and BiOCl) and are composed of flower-like nanostructures. Compared to UV light-responsive BiOCl, all the nanocomposite photocatalysts show a strong light absorbance in the range of 250–800 nm, demonstrating that the Fe₃O₄/BiOCl nanocomposites can respond to visible as well as UV light. Moreover, visible light absorbance was increased with the increase in the Fe₃O₄ amount in the composite. The photocatalytic activity of nanocomposite photocatalysts was evaluated by the photodegradation of Rhodamine B (RhB) over the samples under visible light irradiation. The 10 wt% Fe₃O₄/BiOCl nanocomposite photocatalyst shows the highest photocatalytic efficiency among the samples. The Fe₃O₄/BiOCl nanocomposite photocatalyst was stable under visible light irradiation to efficiently degrade RhB molecules after five cycles and could be easily recovered with a magnet after each cycle.     

Synthesis of Fe3O4/CuO/ZnO/RGO and its catalytic degradation of dye wastewater using dielectric barrier discharge plasma

The design of an efficient and green dye degradation technology is of great significance to mitigate water pollution as well as ecological damage. Fe₃O₄/CuO/ZnO/RGO was prepared by solvothermal synthesis and homogeneous precipitation. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and vibrating-sample magnetometry (VSM) were used to characterize the samples, to explore the morphology and structural composition of the composites. To enhance the degradation efficiency, a dielectric barrier discharge (DBD)–Fe₃O₄/CuO/ZnO/RGO co-catalytic system was created based on the DBD plasma technology. Response surface methodology analysis results demonstrate that the degradation effect of DBD–Fe₃O₄/CuO/ZnO/RGO is optimal and the decolorization rate is 95.06 % when the solution pH is 3, conductivity is 0.5 mS/cm, the input voltage is 90 V, and Fe₃O₄/CuO/ZnO/RGO concentration is 0.18 g/L. Therefore, this study offers a novel method for dye degradation and confirms the viability of a DBD–Fe₃O₄/CuO/ZnO/RGO synergistic catalytic system.     

Fe3O4/reduced graphene oxide‐carbon nanotubes composite for the magnetic solid‐phase extraction and HPLC determination of sulfonamides in milk

A novel magnetic adsorbent Fe₃O₄/reduced graphene oxide‐carbon nanotubes, was prepared by one‐pot solvothermal synthesis method. It was characterized by scanning electron microscopy, X‐ray powder diffraction and vibrating sample magnetometry. The diameter of Fe₃O₄ microparticles was about 350 nm, which were covered by carbon nanotubes and reduced graphene oxide sheets, while carbon nanotubes inserted between the reduced graphene oxide sheets effectively prevented their aggregation. The composite had large surface area and good magnetic property, suiting for magnetic solid‐phase extraction and the determination of sulfonamides, by coupling with high‐performance liquid chromatography. Under the optimized conditions (including extraction time, amount of adsorbent, solution pH, ionic strength and desorption conditions), a good linear was achieved in the concentration range of 5–500 μg/L and the low limits of detection and low limits of quantification were 0.35–1.32 and 1.16–4.40 μg/L, respectively. The enrichment factors were estimated to be 24.72 to 30.15 fold. The proposed method was applied for the detection of sulfonamides in milk sample and the recoveries were 88.4–105.9%, with relative standard deviations of 0.74–5.38%.