Graphene-based Magnetic Nanocomposite Research Articles

Removal of cyanide from the gold cyanidation plant tailings using graphene-based magnetic nanocomposites

Removal of cyanide from the gold cyanidation plant tailings using graphene-based magnetic nanocomposites

Advances in Graphene-Based Magnetic and Graphene-Based/TiO2 Nanoparticles in the Removal of Heavy Metals and Organic Pollutants from Industrial Wastewater

In this review, various graphene-based/TiO2 and graphene-based magnetic nanocomposites which were developed as highly efficient photocatalysts for degrading organic dyes, pharmaceuticals and efficient adsorbent materials for the adsorption of heavy metal ions were reviewed. The nanocomposites revealed the effective adsorptive potential of graphene-based magnetic materials and the efficient photocatalytic ability of graphene-based/TiO2 nanocomposites in decontaminating industrial wastewater containing toxic heavy metals and organic pollutants. The magnetic properties of graphene-based magnetic materials facilitate easy magnetic separation after adsorption of pollutants. The efficient photocatalytic ability of TiO2 semiconductor helps in rapid degradation of organic pollutants while graphene-based materials increase the surface area for adsorption of pollutants. Literature studies show that combinations of synthetic methods have been employed for the generation of various nanocomposite materials such as GO/TiO2, rGO/TiO2, and Fe3O4/GO, that possess photocatalytic activity and magnetic properties for the commercial removal of organic and inorganic pollutants found in water/wastewaters. The photocatalytic performance is connected to the large surface area of graphene derivatives (e.g. GO) that limit electron–hole recombination for TiO2, while the presence of magnetic nanoparticles (e.g. Fe3O4) in heavy metal adsorbent materials facilitates magnetic separation when an external magnetic field is applied.

Removal of Sulfadiazine Using 3D Interconnected Petal-Like Magnetic Reduced Graphene Oxide (MrGO) Nanocomposites

Adsorption has been regarded as one of the most efficient and economic methods for the removal of antibiotics from aqueous solutions. In this work, different graphene-based magnetic nanocomposites using a modified solvothermal method were synthesized and employed to remove sulfadiazine (SDZ) from water. The adsorption capacity of the optimal magnetic reduced graphene oxide (MrGO) was approximately 3.24 times that of pure Fe3O4. After five repeated adsorption cycles, the removal rate of SDZ (100 μg/L) by MrGO nanocomposites was still around 89.3%, which was only about a 3% decrease compared to that in the first cycle. Mechanism investigations showed that both chemical and physical adsorption contributed to the removal of SDZ. The excellent adsorption performance and recyclability of MrGO nanocomposites could be attributed to their wonderful 3D interconnected petal-like structures. The MrGO with SDZ could be easily recollected by magnetic separation. The MrGO also exhibited excellent adsorption performance in the purification of real polluted water.

Preparation and Characterization of a Graphene-Based Magnetic Nanocomposite for the Adsorption of Lanthanum Ions from Aqueous Solution

A graphene-based magnetic nanocomposite (MNGO) was successfully synthesized using a partial reduction co-precipitation method from iron salt solution in graphene oxide (GO) and was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), and nitrogen Brunauer, Emmer, and Teller (BET) measurements. The adsorption of La (III) ions onto the MNGO from the aqueous solution was studied as batch experiments as a function of La (III) ion concentration, pH of the solution, adsorbent dosage, contact time, and temperature. The optimum pH for the adsorption of La (III) ions was shown to be 4.0 for 0.01 g sorbent dosage and the maximum adsorption of La (III) was reached within 15 min. Under the optimum experimental conditions, the adsorption efficiency was determined to be 93%. Moreover, the MNGO exhibited selectivity and interference resistance to coexisting ions for the adsorption of La(III). To determine the adsorption characteristics, models of Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Flory-Huggins, and Brunauer, Emmer, and Teller adsorption isotherms were applied to the measurements. The Langmuir isotherm model describes the experimental data very well. The maximum adsorption capacity of MNGO was found to be 49.75 mg/g for lanthanum under Langmuir isotherm model. Moreover, a chi-squared test was used to determine the fitting degrees of the isotherms using experimental measurements.

Graphene-based magnetic metal organic framework nanocomposite for sensitive colorimetric detection and facile degradation of phenol

Abstract Phenol is a toxic and widely spread as environmental pollutants; the sensitive detection and efficient removal are quite important but challenging. Herein, we take the intrinsic advantages of graphene-based magnetic metal organic framework (MOF) composite as mimic enzyme sensor and Fenton-like catalyst for the colorimetric detection and degradation applications. In this work, magnetic Fe 3 O 4 decorated graphene MOF composite (Fe 3 O 4 /rGO/MOF) was fabricated by a simple strategy for the purpose of well-distributed porous MOF on basal planes of magnetic graphene. The adhesive coating of tannic acid film on both side of magnetic graphene was explored as the directing agent for the controllable self-assembly of MOF. Interestingly, the Fe 3 O 4 /rGO/MOF represent excellent mimic enzyme properties, which can detect phenol based on a visual colour change in water solution. The mimic enzyme senor can oxidize 4-aminoantipyrine in the presence of H 2 O 2 and exhibit strong affinity and selectivity in phenol detection. Simultaneously, Fe 3 O 4 /rGO/MOF also display high degradation ability towards phenol removal. These results indicate that the bifunctional composite can act both as colorimetric senor and Fenton-like catalyst, it would facilitate the real-time monitoring of water quality and wastewater treatment.

Construction of a novel fluorinated graphene-based magnetic nanocomposite and its application in cancer photo-chemotherapy

Fluorinated graphene (FG) inherits the excellent performance of graphene and fluorinated carbon, and has many outstanding properties in biological fields. However, the hydrophobic nature and harsh preparation conditions greatly limit its further functionalization and practical applications. Herein, a novel strategy is reported to prepare water-soluble fluorinated graphene oxide (FGO), and this method also facilitates us for the first time to decorate FGO with magnetic Fe3O4 nanoparticles. The constructed novel (FGO/Fe3O4) nanocomposite not only shows good biocompatibility even at high concentration, but exhibits excellent photothermal efficiency in near infrared region. Moreover, the improved dispersibility and high surface area also enable the nanocomposite to have drug loading capacity, and cell experiment study indicates the nanocomposite is a valuable candidate for cancer photo-chemotherapy.

Functional graphene-based magnetic nanocomposites as magnetic flocculant for efficient harvesting of oleaginous microalgae

Magnetic graphene oxide (GO) nanocomposite was assigned to decorate with cationic polymer PDDA (diallyldimethylammonium chloride) to a sponge like nanocomposite GO-Fe3O4/PDDA, and employed in magnetic harvesting of oleaginous Chlorella sp. HQ. The results showed that huge surface area, light weight and stable dispersion of GO make contribution to the high harvesting efficiency of GO-Fe3O4 (80.14%), compared to Fe3O4 NPs (62.65%) with 70mg of nanomaterials/L of algal cells dose. In addition, graphene base provides more active sites to further decorate with PDDA, which imparts a positive zeta potential charge (21.94mV) to nanoflocculants, thereby achieving 95.35% harvesting efficiency within 5min. The adsorption followed Langmuir isotherm and pseudo-second-order kinetic model, with the maximum adsorption capacity of 14.06g dry-biomass/g. Moreover, the harvesting efficiency decreased dramatically when pH increased for Fe3O4 NPs, while GO-Fe3O4and GO-Fe3O4/PDDA could maintain in a wide pH range. Besides,GO-Fe3O4/PDDA can be effectively reactivated (88.68% harvesting efficiency after 5 times reactivation) with 70mgL−1 dose (add 30mgL−1 after every time). It can be expected that this novel graphene-based magnetic nanocomposite has great potential to be a promising magnetic flocculant applied to efficient harvesting of oleaginous microalgae.

Graphene Oxide-Based Magnetic Solid Phase Extraction Combined with High Performance Liquid Chromatography for Determination of Patulin in Apple Juice

Magnetic solid phase extraction (MSPE) is a valuable tool for the extraction and preconcentration of analytes from environmental, food, and biological samples because of its convenience, promptness, and simplicity. In this study, a graphene oxide-based magnetic nanocomposite (MGO) was synthesized and characterized by various instrumental methods. An effective MSPE procedure coupled with high-performance liquid chromatography (MSPE-HPLC) was developed for the preconcentration and determination of the patulin (PAT) in apple juice samples. Critical experimental parameters of MSPE that could affect the extraction efficiencies, such as the amount of MGO, the pH, and ionic strength of the sample solution; the extraction time; and the desorption conditions, were investigated. After optimizing the conditions, the detection limit of this method provided was 2.3 μg/kg; the recoveries were in the range of 68.7–83.6 %, with relative standard deviations (RSDs) ranging between 1.8–8.7 %. It was confirmed that the graphene-based magnetic nanocomposite was a kind of effective MSPE material used for the PAT analyses in apple juice samples.

PREPARATION AND CHARACTERIZATION OF GRAPHENE-BASED MAGNETIC HYBRID NANOCOMPOSITE

Graphene-based magnetic hybrid nanocomposite has the advantage of exhibiting better performance as platform or supporting materials to develop novel properties of composite by increasing selectivity of the targeted adsorbate. The hybrid nanomaterial was prepared by mixing and hydrolyzing iron (II) and iron (III) salt precursors in the presence of graphene oxide (GO) dispersion through co-precipitation method followed by in situ chemical reduction of GO. The effect of weight loading ratio of Fe to GO (4:1, 2.5:1, 1:1 and 1:4) on structural properties of the hybrid nanomaterials was investigated. The presence of characteristic peaks in FTIR spectra indicated that GO has been successfully oxidized from graphite while the decrease in oxygenated functional groups and peaks intensity evidenced the formation of hybrid nanomaterials through the subsequent reduction process. The presence of characteristic peaks in XRD pattern denoted that magnetite nanoparticles disappeared at higher loading of GO. TEM micrograph showed that the best distribution of iron oxide particles on the surface of hybrid nanomaterial occurred when the loading ratio of Fe to GO was fixed at 2:5 to 1. The reduced graphene oxide (RGO) sheets in the hybrid materials showed less wrinkled sheet-like structure compared to GO due to exfoliation and reduction process during the synthesis. The layered morphology of GO degrades at higher concentrations of iron oxide.

Preparation of Graphene Sheets with Covalently Bonded Fe3O4 for Magnetic Solid-Phase Extraction Applied to Organochlorine Pesticides in Orange Juice

In this paper, a graphene-based magnetic nanocomposite (Fe3O4@G) was synthesized by covalent bonding. The presence of Fe3O4 was characterized by fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM), and transmission electron microscopy. Subsequently, the Fe3O4@G was used as adsorbent for the extraction of eight organochlorine pesticides in orange juice samples prior to their gas chromatography mass spectrometry detection. Various experimental parameters affecting the extraction efficiencies, such as the amount of Fe3O4@G, extraction time, the pH of the sample solution and desorption conditions were investigated. Under optimized experimental conditions, good linearity existed in the range of 1.0–200.0 ng mL−1 for all the analytes with the correlation coefficients (R 2 ) ranging from 0.9904 to 0.9992. The limits of detection (S/N = 3) of the method for the compounds were between 0.01 and 0.05 ng mL−1. Good reproducibilities were obtained with the relative standard deviations (RSDs) below 9.6 %. The recoveries of the method were in the range between 73.8 and 105.4 % with RSDs less than 7.7 %.

Fabrication of CoFe2O4–graphene nanocomposite and its application in the magnetic solid phase extraction of sulfonamides from milk samples

In the present study, a graphene-based magnetic nanocomposite (CoFe2O4–graphene, CoFe2O4–G) was synthesized and used successfully as an adsorbent for the magnetic solid phase extraction (MSPE) of sulfonamides for the first time. The surface morphologies and structures of the CoFe2O4–G nanocomposite were investigated by scanning electron microscopy (SEM), FT-IR, UV–vis spectroscopy, X-ray diffraction (XRD) and vibration sample magnetometer (VSM). Five sulfonamides, including sulfamerazine, sulfamethizole, sulfadoxine, sulfamethoxazole and sulfisoxazole were used as model analytes to evaluate the enrichment properties of the prepared adsorbent in MSPE. After preconcentration, the adsorbent could be conveniently separated from the aqueous samples by an external magnet, and the analytes desorbed from adsorbent were determined by high performance liquid chromatography-ultraviolet detection (HPLC-UV). Extraction parameters including sample pH, amount of sorbent, extraction time and desorption conditions were optimized in detail. Under the optimal conditions, good linear relationships between the peak areas and the concentrations of the analytes were obtained. The linear ranges were 0.02–50.00mgL−1 with correlation coefficients (r)≧0.9982. The limits of detection were less than 1.59μgL−1. Good reproducibility was obtained. The relative standard deviations of intra- and inter-day analysis were less than 4.3% and 6.5%, respectively. The proposed method was successfully applied for the analysis of sulfonamides in milk samples. The average recoveries determined for two milk samples spiked at levels from 5 to 20μgL−1 were 62.0–104.3% with relative standard deviations less than 14.0%. In addition, the CoFe2O4–G could be reused after cleaning with acetone and ultrapure water successively.

Fe2O3@Au core@shell nanoparticle–graphene nanocomposites as theranostic agents for bioimaging and chemo-photothermal synergistic therapy

Graphene-based magnetic and plasmonic nanocomposites (DOX–rGO–Fe2O3@Au NPs) have been prepared for magnetic-field-assisted drug delivery and chemo-photothermal synergistic therapy.

Controllable synthesis and property of graphene-based magnetic metal nanostructures

A facile and effective solution phase reduction method was developed to synthesize graphene-based magnetic metal nanocomposites. Metals (Co, and Ni) or alloys (Fe51Co49, Fe48Ni52, Ni49Co51, Co51Cu49, and Ni52Cu48)/reduced graphene oxide (RGO) nanocomposites were successfully prepared by reduction of the corresponding aqueous metal ions and ethylenediamine (EDA)–graphene oxide (GO) with hydrazine hydrate at 353 K for 1 h under N2 atmosphere. The effects of synthetic parameters such as metal ions concentration, adding sequence of NaOH and N2H4·H2O, linkage agent and reaction time on the formation of nanocomposites were investigated. The experimental results showed that using ethylenediamine and adding sequence played critical roles in the formation of metals or alloys/RGO nanocomposites. Magnetic hysteresis measurements revealed that the as-synthesized metals or alloys in nanocomposites showed excellent soft magnetic behavior with enhanced saturation magnetization, and could have promising applications in biotechnology, catalysis, and magnetic storage devices.

EXTRACTION OF SOME CHLOROPHENOLS FROM ENVIRONMENTAL WATERS USING A NOVEL GRAPHENE-BASED MAGNETIC NANOCOMPOSITE FOLLOWED BY HPLC DETERMINATION

A novel graphene-based magnetic nanocomposite (G-Fe3O4) was prepared and used as an effective adsorbent for the preconcentration of some chlorophenols (2-chlorophenol, 3-chlorophenol, 2, 3-dichlorophenol, 3, 4-dichlorophenol, and 2, 4, 6-trichlorophenol) in environmental water samples followed by high performance liquid chromatography-UV detection. Various experimental parameters that could affect the extraction efficiencies, such as the amount of G-Fe3O4, the extraction time, the pH of sample solution and the desorption conditions, have been investigated. Under the optimum conditions, a good linearity existed in the range of 1.0–100.0 ng mL−1 for all the analytes, with the determination coefficients (r2) ranging from 0.9954 to 0.9992. The limits of detection (S/N = 3) of the method were between 0.10 and 0.12 ng mL−1. The relative standard deviations (RSDs) varied from 2.2% to 7.5% (n = 6), and the recoveries of the method for the analytes at spiking levels of 5.0 and 10.0 ng mL−1 were in the range from 85.6% to 107.3%. The method has been successfully applied for the determination of some chlorophenols in environmental water samples.

Preconcentration of chlorophenols in water samples using three-dimensional graphene-based magnetic nanocomposite as absorbent

In this paper, a novel magnetic solid-phase extraction method using three-dimensional graphene-based magnetic nanocomposite as adsorbent for the preconcentration of several chlorophenols from water samples prior to high-performance liquid chromatography analysis was developed. Various experimental parameters were investigated. Under the optimum conditions, the enrichment factors of the method were in the range of 186–312, and the limit of detection (S/N = 3) was 0.10 ng/mL. The recoveries of the method were in the range between 85.1% and 101.2%. The developed method has been successfully applied to the determination of chlorophenols in environmental water samples.

A graphene-coated magnetic nanocomposite for the enrichment of fourteen pesticides in tomato and rape samples prior to their determination by gas chromatography-mass spectrometry

A graphene-based magnetic nanocomposite (Fe3O4@SiO2–G) was synthesized and used as the adsorbent for the extraction of fourteen pesticides in tomato and rape samples prior to their gas chromatography-mass spectrometry (GC-MS) detection. Various experimental parameters affecting the extraction efficiencies, such as the amount of Fe3O4@SiO2–G, extraction time, the pH and salt concentration of the sample solution and desorption conditions were investigated. Under optimized experimental conditions, good linearity existed in the range of 1.0–100.0 ng g−1 for all the analytes with the correlation coefficients (r) ranging from 0.9972 to 0.9996. The limits of detection (S/N = 3) of the method for the compounds were between 0.005 and 0.030 ng g−1 for the vegetable samples. Good reproducibilities were obtained with the relative standard deviations (RSDs) below 12.5% (n = 5). The recoveries of the method were in the range between 83.2% and 110.3%.

Magnetic three-dimensional graphene solid-phase extraction coupled with high performance liquid chromatography for the determination of phthalate esters in fruit juice

Three-dimensional graphene-based magnetic nanocomposite was synthesized and used as an effective adsorbent for the extraction of phthalate esters from fruit juice prior to high performance liquid chromatography analysis.

Determination of Triazole Fungicides in Vegetable Samples by Magnetic Solid-Phase Extraction with Graphene-Coated Magnetic Nanocomposite as Adsorbent Followed by Gas Chromatography–Mass Spectrometry Detection

A graphene-based magnetic nanocomposites (G-Fe3O4 MNPs) was synthesized and used as the adsorbent for the extraction of some triazole fungicides (triadimefon, paclobutrazol, hexaconazole, myclobutanil, diniconazole, propiconazole, and tebuconazole) in cucumber, cabbage, and tomato samples prior to gas chromatography–mass spectrometry detection. Various experimental parameters affecting the extraction efficiencies, such as the amount of G-Fe3O4 MNPs, extraction time, pH and salt concentration of the sample solution, and desorption conditions were investigated. Under the optimized experimental conditions, the enrichment factors of the method for the analytes were in the range from 461 to 697. The signal response was linear in the range of 0.5–35.0 ng g−1 for all the analytes with the correlation coefficients ranging from 0.9810 to 0.9986. The limits of detection (S/N = 3) of the method for the analytes were between 0.01 and 0.10 ng g−1. The recoveries of the method for the seven triazoles were in the range from 84.4 to 108.2 % with RSDs between 3.4 and 10.6 %.

Magnetic microsphere-confined graphene for the extraction of polycyclic aromatic hydrocarbons from environmental water samples coupled with high performance liquid chromatography–fluorescence analysis

In this paper, a magnetic microsphere-confined graphene adsorbent (Fe3O4@SiO2-G) was fabricated and used for the extraction of five polycyclic aromatic hydrocarbons (fluorene, anthracene, phenanthrene, fluoranthene and pyrene) from environmental water samples prior to high performance liquid chromatography with fluorescence detection. The Fe3O4@SiO2-G was characterized by various instrumental methods. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the pH and ionic strength of sample solution, the extraction time and the desorption conditions, were investigated. Due to the high surface area and excellent adsorption capacity of the Fe3O4@SiO2-G, satisfactory extraction can be achieved with only 15mg of the adsorbent per 250mL solution and 5min extraction. Under the optimum conditions, a linear response was observed in the concentration range of 5–1500ngL−1 for fluorene, 2.5–1500ngL−1 for anthracene and 15–1500ngL−1 for phenanthrene, fluoranthene and pyrene, with the correlation coefficients (r) ranging from 0.9897 to 0.9961. The limits of detection (S/N=3) of the method were between 0.5 and 5.0ngL−1. The relative standard deviations (RSDs) were less than 5.6%. The recoveries of the method were in the range between 83.2% and 108.2%. The results indicated that this graphene-based magnetic nanocomposite had a great adsorptive ability toward the five polycyclic aromatic hydrocarbons from environmental water samples.

Graphene-based magnetic plasmonic nanocomposite for dual bioimaging and photothermal therapy

In recent years, graphene and graphene-based nanocomposites owning to their highly enriched physical and chemical properties have been widely explored for applications in many different fields including biomedicine. In the present work, we decorate graphene oxide (GO) by both iron oxide nanoparticles (IONPs) and gold, forming a multi-functional magnetic & plasmonic GO–IONP–Au nanocomposite with strong superparamagnetism and significantly enhanced optical absorbance in the near-infrared (NIR) region. We then coat the nanocomposite with polyethylene glycol (PEG), obtaining GO–IONP–Au–PEG with high stability in physiological environments and no significant in vitro toxicity. Remarkably enhanced photothermal cancer ablation effect using GO–IONP–Au–PEG is realized in comparison to PEGylated GO used in our earlier studies, as demonstrated in both in vitro cell tests and in vivo animal experiments. Moreover, the IONP and Au compartments in the GO–IONP–Au–PEG nanocomposite could be further taken advantages for magnetic resonance (MR) and X-ray dual-modal imaging. Our work shows the promise of using graphene-based multi-functional nanocomposite as cancer theranostics.