Magnetite Reduced Graphene Oxide Research Articles

Enhancing capacitive performance of magnetite-reduced graphene oxide nanocomposites through magnetic field-assisted ion migration.

The transition towards renewable energy sources necessitates efficient energy storage systems to meet growing demands. Electrochemical capacitors, particularly electric double-layer capacitors (EDLCs), show promising performance due to their superior properties. However, the presence of resistance limits their performance. This study explores using an external magnetic field to mitigate ion transfer resistance and enhance capacitance in magnetite-reduced graphene oxide (M-rGO) nanocomposites. M-rGO nanocomposites with varying weight ratios of magnetite were synthesized and comprehensively characterized. Characterization highlighted the difference in certain parameters such as C/O ratio, the Id/Ig ratio, surface area and particle size that contribute towards alteration of M-rGO's capacitive behaviour. Electrochemical studies demonstrated that applying a magnetic field increased specific capacitance by approximately 20% and reduced resistance by 33%. Notably, a maximum specific capacitance of 16.36 F/g (at a scan rate of 0.1 V/s) and 27.24 F/g (at a current density of 0.25 A/g) was achieved. These improvements were attributed to enhanced ion transportation and migration at the electrode/electrolyte interface, lowering overall resistance. However, it was also observed that the aforementioned parameters can also limit the M-rGO's performance, resulting in saturated capacitive state despite a reduced resistance. The integration of magnetic fields enhances energy storage in nanocomposite systems, necessitating further investigation into underlying mechanisms and practical applications.

The Immobilized Zirconocene Chloride on Magnetite‐reduced Graphene Oxide: A Highly Efficient and Reusable Heterogeneous Nanocatalyst for One‐pot Three‐component Synthesis of Tetrahydrobenzo[b]pyrans and Dihydropyrano[3,2‐c]chromenes

AbstractThe present paper describes the synthesis and characterization of the functionalized magnetite reduced graphene oxide (rGO@Fe3O4) with zirconocene dichloride as rGO@Fe3O4@ZrCp2Cl2. The prepared magnetic nanomaterial was characterized by Fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), inductively coupled plasma optical emission spectroscopy (ICP‐OES) and mass spectrometry (MS). This new heterogeneous nanocatalyst showed the perfect catalytic activity towards synthesis of tetrahydrobenzo[b]pyran and Dihydropyrano[3,2‐c]chromenes derivatives through multicomponent reaction of dimedone or 4‐hydroxycoumarin, malononitrile and aromatic aldehydes in polyethylene glycol 400 (PEG‐400) at 100 °C. The influence of the amount of nanocatalyst, varying temperature of the reaction and the kind of solvent on the rate of condensation reaction was investigated. Recovery and reusability of the applied nanocatalyst was examined for five consecutive cycles without the significant loss of its catalytic activity.

Comprehensive Study on the Reinforcement of Electrospun PHB Scaffolds with Composite Magnetic Fe3O4-rGO Fillers: Structure, Physico-Mechanical Properties, and Piezoelectric Response.

This is a comprehensive study on the reinforcement of electrospun poly(3-hydroxybutyrate) (PHB) scaffolds with a composite filler of magnetite-reduced graphene oxide (Fe3O4-rGO). The composite filler promoted the increase of average fiber diameters and decrease of the degree of crystallinity of hybrid scaffolds. The decrease in the fiber diameter enhanced the ductility and mechanical strength of scaffolds. The surface electric potential of PHB/Fe3O4-rGO composite scaffolds significantly increased with increasing fiber diameter owing to a greater number of polar functional groups. The changes in the microfiber diameter did not have any influence on effective piezoresponses of composite scaffolds. The Fe3O4-rGO filler imparted high saturation magnetization (6.67 ± 0.17 emu/g) to the scaffolds. Thus, magnetic PHB/Fe3O4-rGO composite scaffolds both preserve magnetic properties and provide a piezoresponse, whereas varying the fiber diameter offers control over ductility and surface electric potential.

The role of non-radical pathway in heterogeneous activation of persulfate and H2O2 by superparamagnetic magnetite-reduced graphene oxide nanocomposite

Superparamagnetic magnetite-reduced graphene oxide nanocomposite (Fe3O4-rGO) was synthesized by a one-pot solvothermal method and were characterized by XRD, TEM, FESEM, FTIR, XPS, and VSM analysis. The different systems such as PS/Fe3O4-rGO, H2O2/Fe3O4-rGO, and the combined system of PS + H2O2/Fe3O4-rGO were evaluated for acetaminophen (ACP) degradation under different pH conditions. The study showed the superior activity of PS/ Fe3O4-rGO over the other systems with >98% of ACP removal within 150 min in a wide pH range (3–10). The ACP removal and TOC reduction at acidic pH are as follows; PS/ Fe3O4-rGO > PS + H2O2/ Fe3O4-rGO > H2O2/ Fe3O4-rGO. The investigation of different reactive species involved in these systems showed the predominance of non-radical pathway over the radical pathway for the ACP degradation. The extensively reactive catalyst surface leads to further reactions of radicals to end up with less reactive species. Despite the lower reactivity, the abundance of O2•-, 1O2 are sufficient to carry out the ACP removal with good mineralization. The pathway of ACP degradation in the PS/Fe3O4-rGO system was proposed based on the HR-LC-MS/MS analysis. The applicability of PS/Fe3O4-rGO system was further confirmed by studying the removal of ACP from groundwater. In PS + H2O2/Fe3O4-rGO combined system, the addition of lower polar solvents such as ethanol and t-butanol acted as activity enhancer. Combining PS and H2O2 in the same system to gain more radicals is not a good strategy in terms of economical and reactivity aspects.

The Immobilized Zirconocene Chloride on Magnetite-Reduced Graphene Oxide: A Highly Efficient and Reusable Heterogeneous Nanocatalyst for One-Pot Three-Component Synthesis of Tetrahydrobenzo[B]Pyrans and Dihydropyrano[3,2-C]Chromenes

The Immobilized Zirconocene Chloride on Magnetite-Reduced Graphene Oxide: A Highly Efficient and Reusable Heterogeneous Nanocatalyst for One-Pot Three-Component Synthesis of Tetrahydrobenzo[B]Pyrans and Dihydropyrano[3,2-C]Chromenes

Magnetite–reduced graphene oxide nanocomposite as an efficient heterogeneous Fenton catalyst for the degradation of tetracycline antibiotics

Effective Fenton degradation of tetracycline over magnetite nanoclusters supported on reduced graphene oxide was observed.

Synthesis of MRGO Nanocomposites as a Potential Photocatalytic Demulsifier for Crude Oil-in-Water Emulsion

Oil-in-water (O/W) emulsion has been a major concern for the petroleum industry. A cost-effective magnetite-reduced graphene oxide (MRGO) nanocomposite was synthesized to study the demulsification process of emulsion using said nanocomposite under solar illumination. Characterization data show that the magnetite was successfully deposited on reduced graphene oxide through redox reaction at varying loading amounts of magnetite. Demulsification of the O/W emulsion using MRGO nanocomposite shows that in general the demulsification efficiency was dependent on the loading amount of Fe3O4 on the RGO sheet. It was proposed that the surfactant hydroxyl groups have an affinity towards Fe3O4, which the loading amount was directly proportionate to available active site in Fe3O4. As the loading amount increases, charge recombination centers on the RGO sheet would increase, effectively affecting the charge distribution within MRGO structure.

CuO-decorated magnetite-reduced graphene oxide: a robust and promising heterogeneous catalyst for the oxidative amidation of methylarenes in water via benzylic sp3 C–H activation

CuO-decorated magnetite-reduced graphene oxide: a heterogeneous catalyst for the oxidative amidation of methylarenes in water at room temperature.

Magnetically recoverable magnetite-reduced graphene oxide as a demulsifier for surfactant stabilized crude oil-in-water emulsion.

Oily wastewater, especially water-oil emulsion has become serious environmental issue and received global attention. Chemical demulsifiers are widely used to treat oil-water emulsion, but the toxicity, non-recyclable and non-environmental friendly characteristic of chemical demulsifiers had limited their practical application in oil-water separation. Therefore, it is imperative to develop an efficient, simple, eco-friendly and recyclable demulsifiers for breaking up the emulsions from the oily wastewater. In this study, a magnetic demulsifier, magnetite-reduced graphene oxide (M-rGO) nanocomposites were proposed as a recyclable demulsifier to break up the surfactant stabilized crude oil-in-water (O/W) emulsion. M-rGO nanocomposites were prepared via in situ chemical synthesis by using only one type Fe salt and GO solid as precursor at room temperature. The prepared composites were fully characterized by various techniques. The effect of demulsifier dosage and pH of emulsion on demulsification efficiency (ED) has been studied in detailed. The demulsification mechanism was also proposed in this study. Results showed that M-rGO nanocomposites were able to demulsify crude O/W emulsion. The ED reaches 99.48% when 0.050 wt.% of M-rGO nanocomposites were added to crude O/W emulsion (pH = 4). Besides, M-rGO nanocomposites can be recycled up to 7 cycles without showing a significant change in terms of ED. Thus, M-rGO nanocomposite is a promising demulsifier for surfactant stabilized crude O/W emulsion.

Magnetite-graphene oxide nanocomposites: Facile synthesis and characterization of optical and magnetic property

Graphene based magnetic nanocomposites provides promising applications for flexible transparent electronics due to increase in number of interfaces in nanocomposites which can provide better magnetic coupling. In this present work, magnetite-graphene oxide (MGO) and magnetite-reduced graphene oxide (MRGO) nanocomposites are synthesized with a homogeneous dispersion of Fe3O4 nanoparticles using a facile synthesis method i.e. co-precipitation and reduction processes at room temperature. UV–Visible and Fluorescence spectroscopy techniques are used to study the optical characteristics, while the structural, morphological and compositional characteristics are studied using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) techniques respectively. The magnetic hysteresis curves of MGO and MRGO are measured by the Vibrating Sample Magnetometer (VSM) system. The full hysteresis loop is obtained from −5 kOe to 5 kOe. Both MGO and MRGO nanocomposites have shown superparamagnetism at room temperature. The saturation magnetization obtained for MGO and MRGO is 3.45 emu/g and 3.92 emu/g respectively. Such nanocomposites can be used in graphene based environmental technologies.

Retraction: Simultaneous sorption and reduction of U(vi) on magnetite-reduced graphene oxide composites investigated by macroscopic, spectroscopic and modeling techniques.

Retraction of ‘Simultaneous sorption and reduction of U(vi) on magnetite–reduced graphene oxide composites investigated by macroscopic, spectroscopic and modeling techniques’ by Wencai Cheng et al., RSC Adv., 2015, 5, 59677–59685, DOI: 10.1039/C5RA10451C.

Speciation of mercury using high-performance liquid chromatography-inductively coupled plasma mass spectrometry following enrichment by dithizone functionalized magnetite-reduced graphene oxide

A facile method of magnetic solid-phase extraction high-performance liquid chromatography-inductively coupled plasma mass spectrometry (MSPE-HPLC-ICP-MS) based on a magnetic adsorbent that was prepared by simply and directly adsorbing dithizone on the surface of the magnetite-reduced graphene oxide composites was developed to preconcentrate trace mercury species in environmental samples. Parameters influencing the synthesis of the adsorbents and extraction, including the ratio of GO to iron (III) acetylacetonate, solution pH, adsorption time, desorption time and the component of the eluent, were optimized. Under the optimized conditions, the enrichment factors were 400 and 380 (400 mL water sample) for inorganic mercury (IHg) and methylmercury (MMHg), respectively. The detection limits (3δ) of the proposed method were 0.48 and 0.17 ng L−1 for IHg and MMHg. The spiked recoveries (91.5–111%) and standard deviation (<3.1%) in real water samples indicated that the method had high reproducibility and accuracy. This proposed MSPE-HPLC-ICP-MS method, with simple operation, high enrichment factors and high sensitivity, was successfully applied for the determination of mercury species at trace levels in environmental water samples, including river water, ground water, sea water and sewage effluent, and fish samples.

In vitro apatite mineralization and heat generation of magnetite-reduced graphene oxide nanocomposites for hyperthermia treatment

Nanocomposites of magnetite (Fe3O4) and reduced graphene oxide (rGO) generate heat under an alternating magnetic field and therefore have potential applications as thermoseeds for cancer hyperthermia treatment. However, the properties of such nanocomposites as biomaterials have not been sufficiently well characterized. In this study, the osteoconductivity of Fe3O4-rGO nanocomposites of various compositions was evaluated in vitro in terms of their apatite-forming ability in simulated body fluid (SBF). Furthermore, the heat generation of the nanocomposites was measured under an alternating magnetic field. The apatite-forming ability in SBF improved as the Fe3O4 content in the nanocomposite was increased. As the Fe3O4 content was increased, the nanocomposite not only rapidly raised the surrounding temperature to approximately 100 °C, but the specific absorption rate also increased. We assumed that the ionic interaction between the Fe3O4 and rGO was enhanced and that Brown relaxation was suppressed as the proportion of rGO in the nanocomposite was increased. Consequently, a high content of Fe3O4 in the nanocomposite was effective for improving both the osteoconductivity and heat generation characteristics for hyperthermia applications.

Optimization and characterization of magnetite-reduced graphene oxide nanocomposites for demulsification of crude oil in water emulsion.

Oily wastewater from the oil and gas industry negatively affects the environment. Oily wastewater typically exists in the form of an oil-in-water emulsion. Conventional methods to treat oily wastewater have low separation efficiency and long separation time and use large equipment. Therefore, a simple but effective method must be developed to separate oil-in-water emulsions with high separation efficiency and short separation times. Magnetite–reduced graphene oxide (M–RGO) nanocomposites were used as a demulsifier in this work. Magnetite nanoparticles (Fe3O4) were coated on reduced graphene oxide (rGO) nanosheets via an in situ chemical synthesis method. The synthesized M–RGO nanocomposites are environmentally friendly and can be recovered after demulsification by an external magnetic field. M–RGO characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning microscopy, Raman spectroscopy, and vibrating sample magnetometry. Demulsification performance was evaluated in terms of M–RGO dosage, effects of pH, and brine concentration. The demulsification capability of M–RGO was determined based on the residual oil content of the emulsion, which was measured with a UV-vis spectrometer. The response surface method was used to determine the optimum conditions of the input variables. The optimum demulsification efficiency achieved at pH 4 and M–RGO dosage of 29 g L−1 was approximately 96%. This finding demonstrates that M–RGO nanocomposites are potential magnetic demulsifiers for oily wastewater that contains oil-in-water emulsions. Also, the recyclability of this nanocomposite has been tested and the results shown that it is a good recyclable demulsifier.

Elaboration of nano titania-magnetic reduced graphene oxide for degradation of tartrazine dye in aqueous solution

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).

Effect on the Formation of Magnetite Reduced Graphene Oxide with Controlled Stirring Duration

Graphene is a promising material due to its fascinating properties, such as mechanical, electronic and thermal properties. Graphene based hybrids materials also have been widely studied due to its wide applications, such as sensors, energy storage and conversion, electronic device and others. The current study presents the synthesis of magnetite-reduced graphene oxide (M-rGO) nanocomposites through in situ chemical synthesis at different stirring durations. This synthesis process involves the redox reaction between the iron(II) salts and graphene oxide (GO) sheets. Various techniques were employed to characterize the synthesized M-rGO nanocomposites. From X-ray diffraction (XRD) results, the crystal structure of M-rGO was found to be independent on the stirring duration. Three magnetite vibrations, D band and G band were observed in Raman spectrum of M-rGO with 24 hours stirring duration. From Fourier transform infrared (FTIR) analysis, M-rGO with 24 hours stirring duration showed the strong intensity of Fe-O vibration. Thus, this indicated that a large amount of magnetite nanoparticles were covered on the surface of rGO sheets. This result is further supported by the morphology of nanocomposites from scanning electron microscopy (SEM) and the elemental analysis (EDX). A monolayer of rGO sheet (C= 33.79 atomic %) with full coverage of magnetite nanoparticles (Fe= 30.20 atomic %) was found for the M-rGO with 24 hours stirring duration. Overall, M-rGO require 24 hours of continuous stirring to ensure full coverage of magnetite nanoparticles on the surface of rGO sheets.

Potential of magnetite reduced graphene oxide/chitosan nanocomposite as biosorbent for the removal of dyes from aqueous solutions

In this study, the fast and considerable adsorption of Remazol Black B (RBB) and Acid Red 22 (AR22) from an aqueous solution by magnetite reduced graphene oxide (rGO)/chitosan nanocomposite was studied. Several important parameters influencing the adsorption of dye pollutants such as pH (1–8), sorbent mass (5–25 mg), contact time (30–180 min), and dye concentration (10–50 ppm) were considered. The results showed that, the surface property of rGO, the amino, and hydroxyl functional groups of chitosan, and the magnetic property of Fe3O4, the adsorbent possesses quite good adsorption capacity to the dye under investigation. Both dye solutions sorption on nanocomposite was strongly dependent on pH. An adsorption efficiency of 95.32 and 99.46% could be achieved at initial RBB and AR22 concentrations of 20 mg/mL, respectively. In the aqueous solution of RBB and AR22, the adsorption data could be fitted by the Langmuir and Freundlich equations, respectively. In addition, the adsorption kinetics of RBB and AR22 were investigated to show that it was well‐described by Elovich and Blanchard models, respectively. These results indicate that magnetite reduced GO/chitosan nanocomposite could be regarded as a potential biosorbent for RBB and AR22 dye removal in wastewater treatment process. POLYM. COMPOS., 39:E457–E462, 2018. © 2017 Society of Plastics Engineers

Fabrication and Characterization of Nano Titania-Magnetic Reduced Graphene Oxide with Highly Photocatalytic Degradation of Tartrazine Dye

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrate intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photoactivity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of (TZ) by MRGT composites under visible light irradiation was examined by varying the operational parameters such as photocatalyst amounts, organic dye concentrations, and irradiation time. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (UV-vis/DRS) -, Raman and vibrating sample magnetometer (VSM). The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10 % respectively, Whereas for MRGT it was more than 95% . The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhance the photocatalytic effienecy of the composite in visible light.

Fabrication of new magnetite-graphene nanocomposite and comparison of its laser-hyperthermia properties with conventionally prepared magnetite-graphene hybrid

A single step supercritical method was introduced for synthesis of “magnetite - reduced graphene oxide (M-rGO)” composite in supercritical methanol. Modified surface, smaller size, lesser cytotoxicity, and homogenous dispersion of Fe3O4 nanoparticles on the graphene surface were advantages of this new M-rGO composite in comparison to the materials synthesized by conventional wet chemical method (M-GO). Nanocomposites were injected in tissue equivalent phantoms of agarose gel in 10mg/g dosage, and were irradiated by a 1600mW laser beam at wavelength of 800–810nm. The M-rGO and M-GO were found to be the most and the least efficient samples for increasing the temperature of the phantom. As for mathematical analysis of the heating process, a heat transfer model was developed and solved by the COMSOL Multiphysics software. Results showed an appreciable agreement with the experiments and revealed enhancement in thermal conductivity and light absorption coefficient of tissue by injecting of M-rGO sample. Our findings showed that M-rGO is a promising material for laser hyperthermia, which can deposit adequate heat dose with desirable effect in the tumorous cells in a short period.

Synthesis of Novel Graphene Composite Adsorbent for Water Treatment By Adsorption and Electrochemical Regeneration

One of the efficient and cost effective ways to remove organic contaminants from water is adsorption coupled with electrochemical oxidation. Graphite intercalated compounds (GIC) and activated carbons (AC) are among the common adsorbents for the adsorption - electrochemical regeneration process; nevertheless, they have significant shortcomings, i.e. GIC has low adsorptive capacity, whereas AC requires long regeneration time and high energy consumption associated with low current efficiency and high cell voltages. Owing to their huge surface area and high electrical conductivity, graphene-based materials are promising candidates as adsorbents suitable for electrochemical regeneration. This results in higher adsorptive capacity and current efficiency compared to AC and GIC. In this study, we prepared different types of graphene-based materials, namely graphene foam and magnetite reduced graphene oxide (rGO). The synthesized materials were characterized and tested for adsorption and electrochemical regeneration. Our findings revealed that, in addition to high current efficiency (greater than 80 %), these materials had a good adsorptive capacity compared to GIC. However, during the regeneration, graphene was oxidized and corroded after only a few cycles, contaminating the treated water. In the case of graphene foam, the integrity of the foam was lost after electrochemical regeneration. In order to overcome this corrosion problem and increase the current efficiency, a new composite was developed that is resistant to oxidation. The composite was characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. Methylene blue was employed as a model adsorbate in synthetic wastewater samples. Regeneration was carried out in an electrolytic cell operated at a constant current. In spite of the slight reduction in adsorptive capacity compared to the pure graphene, the composite facilitated the oxidation of the organics to an extent in which a current efficiency of around 100 % was achieved. TEM images indicated that the composite was not significantly corroded during the electrochemical treatment. Even after ten cycles of adsorption and regeneration, no reduction in the adsorptive capacity and no contamination of the treated water was observed. In brief, the results of the current study introduce graphene composites as efficient materials for the adsorption - electrochemical regeneration process.