Fe3O4 SiO2 Research Articles

Silica-coated magnetic Fe3O4 nanoparticles as efficient nano-adsorbents for the improvement of the vapor-phase adsorption of benzene

This study focused on the synthesis of silica-coated magnetic Fe3O4 (Fe3O4@SiO2) nanoparticles and their application for the improvement of the vapor-phase adsorption of benzene. The magnetic Fe3O4@SiO2 nanoparticles were synthesized according to the co-precipitation method, while their characterization was performed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area analyses. The experimental parameters were optimized to achieve the maximum adsorption capacity for the vapor-phase benzene by Box-Behnken design (BBD) under response surface methodology (RSM). The magnetic Fe3O4@SiO2 nanoparticles adsorbed 197.50 mg/g of the vapor-phase benzene under the following optimum conditions: 39.48 min residence time, 14.21 ppm initial benzene concentration and 26.51°C temperature. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were used to evaluate the adsorption equilibrium data, and the results were found to be well fitted to the D-R model. The kinetic data obeyed the pseudo-second-order kinetic model for the vapor-phase adsorption of benzene by magnetic Fe3O4@SiO2 nanoparticles. This study demonstrated the application potential of magnetic Fe3O4@SiO2 nanoparticles as promising low-cost nano-adsorbents for the vapor-phase adsorption of benzene.

Enhanced oil recovery using hyperbranched polyglycerol polymer-coated silica nanoparticles

Functionalized Fe3O4–SiO2 magnetic nanoparticles (Fe–Si-MNPs) coated with hyperbranched polyglycerol polymer were prepared and tested for oil recovery from oil in water (O/W) emulsions. The structure, chemistry, and surface modifications of the newly developed demulsifier (PSiMNPs) were analyzed, and the percentage demulsification efficiency (%ηdem) was tested at differing concentrations of surfactant (Csur), oil (Coil), and demulsifier (DPSiMNPs). The developed PSiMNPs can be separated from the solution by a magnetic field, regenerated using ethanol, and reused several times. The reported %ηdem was ≥80% for all the studied Coil. The %ηdem improved as the Csur and pH decreased, with maximum values of 98.8% and 98.5% achieved at Csur = 0.05 g/L and a pH = 4, respectively. A DPSiMNPs = 100 mg/L was sufficient to achieve %ηdem of 99.4% for Coil = 100 mg/L and slightly decreased to ~93% for Coil ~4000 mg/L. The PSiMNPs can be reused up to 15 times with a steady %ηdem of 89.1% for Coil = 100 mg/L and 88.6% for Coil = 4000 mg/L. The adsorption of oil on the PSiMNPs follows Freundlich isotherm with maximum adsorption capacity (qmax) of 192.8 g/mg and Langmuir constant (b) of 28.06 mg/L for Coil = 900 mg/L. The qmax of the recycled PSiMNPs slightly decreased to 189.08 g/mg. The kinetic of oil recovery follows the PSO with a K2 of 0.0169 g/mg. min. Surface modification of Fe–Si-MNPs enhanced the oil adsorption, increased the adsorption capacity, and extended the service life resulting in a better cost and process feasibility.

Environmentally benign melamine functionalized silica-coated iron oxide for selective CO2 capture and fixation into cyclic carbonate

The development of new materials capable of fixing CO2 into value-added products has become an exciting research field. Besides mitigating the rising level of CO2, such materials also enable CO2 as a C1 carbon source for useful industrial synthons. This article reports on the stepwise synthesis of a melamine functionalized silica-coated iron oxide (FSNM) material for selective CO2 capture and its catalytic conversion into a useful product. The synthesis of FSNM has been achieved by covalently grafting the melamine group in the pores of mesoporous silica-coated Fe3O4 (Fe3O4@SiO2) particle using isocyanate as a cross-linker. While the Fe3O4 core, owing to its superparamagnetic property, enables the easy retrieval of the material from the reaction mixture and, thus, enhances the recyclability, mesoporous silica coating offers a larger surface area for adsorption. The organic functionalities, containing melamine and carbamide moieties, facilitate the selective adsorption of CO2 on the material with a maximum CO2 uptake of 0.48 mmol/g at 1 bar and 298 K with excellent CO2/N2 selectivity. Moreover, the acid-base interactions between the acidic CO2 and basic amine groups enable the FSNM to catalyze the cycloaddition of CO2 with different epoxides to afford a series of cyclic carbonates, in the presence of tetrabutylammonium bromide (TBAB) as a co-catalyst, under facile and solvent-free conditions. These results strongly support that melamine functionalized Fe3O4@SiO2 affords new aspects towards environmentally friendly and recoverable hybrid adsorbent for adsorption and fixation of CO2 into the valuable products.

Preparation and Characterization of Silica-Coated Iron Oxide Nanoparticles (Fe3O4@SiO2 NPs)

In this study, this SiO2 has been coated on the surface of Fe3O4 (Fe3O4@SiO2) by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) under alkaline medium at 80oC. It was found that only 500 mL TEOS is required to obtain the best coated Fe3O4 core structures which has been confirmed from its TEM micrograph. FTIR analyses revealed the formation of Si-O-Si bonds at 1084.2–1101.4 cm-1 hence confirmed that SiO2 has been successfully coated the Fe3O4 core. From the FESEM analyses, the average size of silica was ~ 50 -70 nm. EDX of the Fe3O4@SiO2 showed that silica had been effectively bonded onto the surface of Fe3O4. The VSM measurements confirmed the superparamagnetic properties of Fe3O4@SiO2 that is desirable for biomedical applications.

Synthesis and optimization of a green and efficient sorbent for removal of three heavy metal ions from wastewater samples: kinetic, thermodynamic, and isotherm studies

A novel, green, and stable sorbent (Fe3O4@SiO2@l-Cysteine functionalized magnetic graphene oxide nanocomposites) was synthesized based on a chemical procedure to remove chromium(VI), lead(II), and cadmium(II) ions from wastewater samples. The l-Cysteine functionalized magnetic graphene oxide as a sorbent component was prepared based on the formation of the covalent bonding between graphene oxide and l-Cysteine. The percentages of the sorbent components, including Fe3O4 NPs, SiO2, and C-FGO were optimized using a D-optimal mixture design to enhance the sorbent stability, selectivity, and affinity toward the heavy metal ions. Besides, the critical factors on the heavy metal ion adsorption were investigated and optimized by a two-level full factorial central composite design. Electrostatic attraction is responsible for the adsorption of these ions on the sorbent, which is highly dependent on pH value. The kinetic study shows that the adsorption of these metal ions onto the sorbent follows the pseudo-second-order rate. The experimental results were investigated using the Freundlich and Langmuir models to determine the isotherm model, indicating the Freundlich isotherm model can well describe the adsorption procedure on the sorbent. The maximum adsorption capacity of 476.19, 526.32, and 588.23 mg g−1 was calculated for the Cr(VI), Pb(II), and Cd(II) ions with favorable adsorption and high affinity, respectively. The study of thermodynamic parameters indicates that the adsorption of these ions onto the sorbent is endothermic and chemical in nature. Moreover, the adsorption process is spontaneous in the temperature range of 278–328 K for removing these heavy metal ions. The obtained results confirm that the proposed sorbent is very suitable for the removal of the Cr(VI), Pb(II), and Cd(II) ions from electroplating wastewater samples with many advantages such as high efficiency, environment-friendly, low cost, and short absorption time.

Self-assembly of superstructures at all scales

Summary Controllable assembly of molecular and nanoscale building blocks into uniform superstructures up to bulk dimensions remains a key challenge in the next phase of nanotechnology development. Here, we report the self-assembly of superstructures at all scales by taking advantage of the partial miscibility of water and 1-butanol to generate transient aqueous emulsion droplets that can encapsulate the target materials and introduce them into template holes. Further diffusion of water into 1-butanol depletes the emulsion droplets, assembling the building blocks into one well-defined superstructure in each hole. Superstructuring of various types and shapes of nanoparticles, biomolecules, and inorganic compounds could be achieved without the need for surfactants and chemical modifications. The versatility, scalability, low-cost, and accurate positioning are crucial advantages for the future development of advanced precision manufacturing.

Metabolic integration of azide functionalized glycan on Escherichia coli cell surface for specific covalent immobilization onto magnetic nanoparticles with click chemistry

A method for specific immobilization of whole-cell with covalent bonds was developed through a click reaction between alkyne and azide groups. In this approach, magnetic nanoparticle Fe3O4@SiO2-NH2-alkyne was synthesized with Fe3O4 core preparation, SiO2 coating, and alkyne functionalization on the surface. The azides were successfully integrated onto the cell surface of the recombinant E. coli harboring glycerol dehydrogenase, which was employed as the model cell. The highest immobilization yield of 83% and activity recovery of 94% were obtained under the conditions of 0.67 mg mg−1 cell-support ratio, pH 6.0, temperature 45 °C, and 20 mM Cu2+ concentration. The immobilized cell showed good reusability, which remained over 50% of initial activity after 10 cycles of utilization. Its activity was 9.7-fold higher than that of the free cell at the condition of pH 8.0 and each optimal temperature. Furthermore, the immobilized cell showed significantly higher activity, operational stability, and reusability.

Functionalized magnetic nanoparticles Fe3O4@SiO2@PTA (PTA = (2-pyrimidylthio)acetic acid) for efficient removal of mercury from water

Functionalized magnetic nanoparticles were prepared by anchoring (2-pyrimidylthio)acetic acid on to the surface of the silica coated Fe3O4 (Fe3O4@SiO2) nanoparticles by acid amide coupling reaction. These nanoparticles were characterized on the basis of powder-XRD, FTIR, FESEM, HRTEM and EDX analysis. The adsorption property of these functionalized nanoparticles (Fe3O4@SiO2@PTA) was investigated in water with a large number of metal ions and anions, which revealed that it selectively adsorbs Hg2+ with high efficiency (920 mg/g). The desorption of Hg2+ from Fe3O4@SiO2@PTA-Hg2+ was successfully carried out with the aid of EDTA and the process was repeated three times successfully to examine its reusability. The adsorption of Hg2+ was also investigated with the variation of pH in the range 2–8 and maximum adsorption was noted at the pH 7.0. Detail study on adsorption suggests that out of the two adsorption isotherm models, Langmuir and Freundlich, the former one (Langmuir) fits better in this case. Detail kinetic study on the adsorption process was also carried out and the data fitted with both the two semi-empirical kinetic models, pseudo-first-order and pseudo-second order, out of which the pseudo second-order model exhibited excellent fitting with correlation coefficient R2 = 0.99 for all concentrations of Hg2+. Finally, on the basis of experimental data, the mechanism for interaction of Hg2+ with Fe3O4@SiO2@PTA nanoparticle is discussed.

DNA methyltransferase 3 beta regulates ras related domain family 1 methylation leading to enhanced proliferation and migration in gastric cancer cells

Silencing expression of RASSF1A, which is induced by DNA hypermethylation, contributes to proliferation and migration in gastric cancer. However, the molecular mechanisms of this process remain unclear. In order to investigate the effect and mechanisms of RASSF1A methylation on proliferation and migration of gastric cancer, DNA methyltransferase inhibitors (5-AZA-CdR) were used to interfere with expression of DNMT3B and RASSF1A in gastric cancer AGS cells. Fe3O4–SiO2 nanoparticles were used to extract mRNA for RT-qPCR, and RT-qPCR and western blotting were used to measure the effect of RASSF1A expression on the expression of Caspase 3, Bcl-2, and Bax in AGS cells. MTT and cell scratch assays were used to assess the proliferation and migration of AGS cells. Our findings show that DNA methyltransferase inhibitors inhibit expression of DNMT3B, which leads to an increase in the expression of RASSF1A, Caspase3, and Bax at both the mRNA and protein levels, and inhibits the expression of Bcl-2. Thus, inhibiting the expression of DNMT3B and altering levels of DNA methylation can promote the expression of RASSF1A, regulate the expression of apoptosis-related genes, and inhibit proliferation and migration of gastric cancer cells. It is helpful to explore the pathological mechanism of endometrial cancer and provide theoretical basis for RASSF1A as a potential therapeutic target of gastric cancer.

Sulfonic acid-modified polyacrylamide magnetic composite with wide pH applicability for efficient removal of cationic dyes

In order to deal with the increasingly serious water pollution caused by dye wastewater, a novel sulfonic acid-modified polyacrylamide magnetic composite (Fe3O4@SiO2/P(AM-AMPS)) was facilely prepared by crosslink reaction. The physicochemical properties and adsorption performances of Fe3O4@SiO2/P(AM-AMPS) were systematically studied by different characterization techniques and a series of batch experiments, respectively. It was found that the adsorption capacities of Fe3O4@SiO2/P(AM-AMPS) towards cationic dyes crystal violet (CV) and methylene blue (MB) were largely enhanced than those of silica-coated Fe3O4 (Fe3O4@SiO2) and maintained at relatively high levels in a wide pH range, due to the three-dimensional network structure and abundant functional groups of modified polyacrylamide. Besides, owing to the introduction of Fe3O4@SiO2, Fe3O4@SiO2/P(AM-AMPS) presented a unique magnetic property that helped it to be rapidly separated from water in a magnetic field. The maximum adsorption capacities of Fe3O4@SiO2/P(AM-AMPS) were 2106.37 mg g−1 for CV removal and 1462.34 mg g−1 for MB removal at 298.15 K, much higher than those of other reported magnetic composites. Furthermore, Fe3O4@SiO2/P(AM-AMPS) was effectively regenerated with HCl solution and the regeneration rates were higher than 97% and 80% for CV and MB removal after five adsorption-desorption cycles, respectively. With its excellent adsorption capacity, wide pH applicability, high separation speed, and satisfactory regeneration ability, Fe3O4@SiO2/P(AM-AMPS) was expected to become a promising adsorbent in the purification of cationic dye wastewater.

Microbial Diversity and Physicochemical Characteristics of the Maotai-Flavored Liquor Fermentation Process.

The grains fermented in Maotai-flavored liquor can be classified into two groups: high-temperature fermented grains generated by stacking and grains fermented in pits. The Maotai-flavor making process enriches a special microbiota from the fermented grains, which makes related studies more difficult. The use of modern molecular techniques to detect and analyze diversity and changes in total bacterial (16S rRNA sequencing) and fungal (internal transcribed spacer (ITS) sequencing) counts have helped to overcome the shortcomings of traditional technological research. The total RNA extracted by Fe₃O₄-SiO₂ nanoparticles was retrieved into DNA by MagBeads Total RNA Extraction Kit. However, discrepancies exist in the microbial community structures at different fermentation periods. Dominant bacteria include Escherichia-Shigella, Lactobacillus, Clostridium, and Streptococcus species and dominant fungi include Alternaria, Ciliophora, Pyrenochaetopsis, Cyphellophora, Aspergillus, Issatchenkia, Pichia, Candida, and Zygosaccharomyces species. Analyses of the enzymatic activity of samples at different fermentation stages have revealed that some existing bacilli influence amylase activity. Here, to investigate flavor changes during each fermentation round, the liquor quality at all rounds was comprehensively assessed based on the corresponding physicochemical properties, which were summarized by sensory evaluation. These results suggested that the liquor quality in the third, fourth, and fifth fermentation rounds was superior.

Affinity Based Nano-Magnetic Particles for Purification of Recombinant Proteins in Form of Inclusion Body

Background:Protein purification is the most complicated issue in the downstream processes of recombinant protein production; therefore, improved selective purification methods are important. Affinity-based protein purification method using His-tag and Ni-NTA resins is one of the most common strategies. MNPs can be used as a beneficial alternative for Ni-NTA resins. However, there is no data on the capability of MNPs for protein purification from inclusion bodies; this issue is studied here. Methods:Recombinant His-tagged proteins of EGFP-His and SK-His were expressed in E. coli BL-21 (DE3) in soluble and inclusion body forms, respectively. MNPs including Fe3O4 magnetic core, SiO2 shell, and Ni2+ on the surface were synthesized by sol-gel and hydrothermal reactions and then characterized by XRD, VSM, and SEM imaging. Both synthesized Fe3O4@NiSiO3 and Fe3O4@NixSiOy MNPs were employed to purify EGEP-His and SK-His under native and denaturing conditions, respectively. The quantity and purity of purified proteins were analyzed by micro-Bradford assay and SDS-PAGE, respectively. Results:Both synthesized MNPs were spherical and well-dispersed with the size ranging from 290 to 415 nm. Synthesized MNPs contained Fe3O4, SiO2 shell, and Ni2+ on their structures with suitable magnetization properties. Using Fe3O4@NiSiO3 and Fe3O4@NixSiOy yielded 192 and 188 µg/mg of SK-His, as compared to 207 and 195 µg/mg of EGFP-His, respectively. Conclusion:MNPs containing magnetic Fe3O4 core, SiO2 shell, and Ni2+on their surface are versatile alternatives for Ni-NTA resins in protein purification for proteins expressed in both soluble and inclusion body forms.

Development of magnetic solid phase extraction platform for the purification of bioactive γ-glutamyl peptides from garlic (Allium sativum)

A magnetic solid phase extraction (MSPE) platform was developed as an alternative to industrial chromatography for purification of bioactive gamma-glutamyl peptides from crude garlic extract. Core-shell C18-functionalized Fe3O4–SiO2 nanoparticles were prepared and characterized for use as magnetic adsorbents. Key MSPE variables, i.e. (1) garlic extract's pH, (2) eluent type, (3) adsorbent concentration, and (4) extraction time, were investigated to determine the optimal MSPE condition. The results showed that the purification favored weakly-acidic pH for both the garlic extract and eluent due to the higher solubility of the peptides and the impurities at acidic pH. At the optimal condition, nearly 80% of the impurities were removed, while the peptides present in the crude garlic extract were mostly retained in the final product. Mass spectrometry verified that the peptides' molecular structure remained intact after purification. The nanoparticle adsorbent remained effective after multiple cycles of MSPE and prolonged storage. The present work successfully established MSPE as a simple, cost-effective, and environmentally-friendly purification technique for bioactive peptides.

Synthesis of Fe3O4/SiO2/TiO2-Ag Photo-Catalytic Nano-structures with an Effective Silica Shell for Degradation of Methylene blue

In this research, Fe3O4/SiO2/TiO2-Ag (FST-Ag) nanoparticles were provided with chemical techniques (sol–gel) during successive steps. At first, Fe3O4 nanoparticles were synthesized via co-precipitation method. Then, Fe3O4/SiO2 (FS) core/shell particles were prepared in presence of different amounts of TEOS precursor. Next, deposition of TiO2 shells was obtained using hydroxypropyl cellulose (HPC) polymer (as a surfactant) to prevent the agglomeration. Finally, Ag nanoparticles deposited on Fe3O4/SiO2/TiO2 (FST) core/shell/shell structure using polyvinyl pyrrolidone (PVP) polymer. The prepared nanoparticles were characterized by XRD, FESEM (with EDX), and TEM techniques. Magnetic properties of the prepared composites were studied by VSM. The result revealed Fe3O4/SiO2/TiO2-Ag nanoparticle photo-catalyst with core/shell magnetic structure were synthesized successfully at each step in presences of suitable additives. Photocatalytic performance of the nanoparticles indicated that Ag nanoparticles increased the removal of methylene blue up to 83% after 3 h. The magnetic properties of these particles also showed that after deposition of layers, nanoparticles have a good ability for the recovery and separation from the solution.

Flocculation-Magnetic Separation Technology for the Rapid Treatment of First Flush Rain

In order to rapid treatment of first flush rainwater, a new flocculation-magnetic microsphere was prepared. And magnetic microspheres were prepared using the modified Stöber method. Magnetite (Fe3O4)-silica (SiO2) core-shell microspheres have superparamagnetism verified by using XRD, FTIR and VSM analysis. Also, Fe3O4/SiO2 (FS) microspheres have no significant reduction after at least reused five times. The optimal feeding order and conditions were flocculant, magnetic powder and PAM, reaction temperature 25 °C, static sedimentation time 30 min, and pH=7. Under the optimized condition, 62% of COD and 98% of turbidity were removed. Especially, Fe3O4/SiO2 microspheres can effectively adsorb heavy metal ion.

Insight into enhanced visible light photocatalytic activity of Fe3O4–SiO2–TiO2 core-multishell nanoparticles on the elimination of Escherichia coli

A nano photocatalyst of Fe3O4–SiO2–TiO2 (FST) was produced, which can be used as a magnetic adsorbent in water treatment e.g. elimination of E.coli. Synthesis of shells on the initial Fe3O4 nanocores was carried out via the sol-gel technique. VSM, PSA, XRD, TEM, FE-SEM, EDS, FTIR and ZETA were analyses conducted for characterization. A 10-nm-passive layer of silica was formed between magnetic core and titania shell to inhibit direct contact of core and shell while superparamagnetic property was preserved. For TiO2 synthesis, it was found that the “concentration of water” and “mixing order of water and TBOT (Titanium butoxide)” had significant effect. Moreover, a minimum ratio of water to TBOT was required for TiO2 nucleation on Fe3O4–SiO2 (FS) seeds. Furthermore, an increment of water concentration to 3.8 M has led to 95% TiO2 coverage on FS nanoparticles. Results showed that FST nanoparticles were completely stable at pH = 7 and had acceptable zeta potential approximately −65 mV. Also, TiO2-coated magnetite nanoparticles (FT) were synthesized with the same condition of FST, but without silica midlayer, in order to observe th effect of SiO2 in nanostructure. Treatment of FST nanoparticles with E.coli showed 98% bacteria adsorption after 100 min, as well significant damage to bacteria cell membrane, was observed by SEM images. However, FT nanoparticles represented 82% bacteria removal with no harsh damage to the cells. This work demonstrated effective presence of SiO2 as a passive layer between Fe3O4 and TiO2 for photocatalytic efficiency improvement.

Heavy metal adsorption efficiency magnetic porous composites Fe3O4–SiO2–APTES

Heavy metal adsorption efficiency magnetic porous composites Fe3O4–SiO2–APTES

Synthesis of magnetic nanoparticles with an IDA or TED modified surface for purification and immobilization of poly-histidine tagged proteins.

Magnetic nanoparticles (MNPs) chelating with metal ions can specifically interact with poly-histidine peptides and facilitate immobilization and purification of proteins with poly-histidine tags. Fabrication of MNPs is generally complicated and time consuming. In this paper, we report the preparation of Ni(ii) ion chelated MNPs (Ni-MNPs) in two stages for protein immobilization and purification. In the first stage, organic ligands including pentadentate tris (carboxymethyl) ethylenediamine (TED) and tridentate iminodiacetic acid (IDA) and inorganic Fe3O4–SiO2 MNPs were synthesized separately. In the next stage, ligands were grafted to the surface of MNPs and MNPs with a TED or IDA modified surface were acquired, followed by chelating with Ni(ii) ions. The Ni(ii) ion chelated forms of MNPs (Ni-MNPs) were characterized including morphology, surface charge, structure, size distribution and magnetic response. Taking a his-tagged glycoside hydrolase DspB (Dispersin B) as the protein representative, specific interactions were confirmed between DspB and Ni-MNPs. Purification of his-tagged DspB was achieved with Ni-MNPs that exhibited better performance in terms of purity and activity of DspB than commercial Ni-NTA. Ni-MNPs as enzyme carriers for DspB also exhibited good compatibility and reasonable reusability as well as improved performance in various conditions.

1D flower-like Fe3O4@SiO2@MnO2 nanochains inducing RGO self-assembly into aerogels for high-efficient microwave absorption

One-dimensional (1D) microwave absorbing materials (MAMs) can induce self-assembly of graphene into aerogels, which provides ideas for the preparation of new MAMs. In here, 3D flower-like Fe3O4@SiO2@MnO2@reduced graphene oxide (RGO) (FSMG) composite aerogels have been fabricated via hydrothermal method, in which 1D Fe3O4@SiO2 (FS) nanochains and two-dimensional (2D) MnO2 sheets form a nano-scale core-shell structure on the surface of the RGO nanosheets. The unique microstructure of aerogels greatly enhances the microwave absorption capability. Particularly, the addition of RGO regulates the complex permittivity and improves the impedance matching of 1D Fe3O4@SiO2@MnO2 (FSM) nanochains. Results demonstrate that the well-designed 3D conductive networks with significant oxygen vacancy defects powerfully favor the electromagnetic wave (EMW) absorption. The as-prepared FSMG composite aerogels show efficient microwave absorption (MA) properties with the maximum effective absorption bandwidth (EAB) of 4.26 GHz (7.13–11.39 GHz) at the corresponding coating thickness of 3.2 mm, accompanied by the minimum reflection loss (RLmin) of about −55.01 dB. This work indicates that the FSMG composite aerogels are excellent absorbers with wide bandwidth, strong absorption, thin thickness and light weight, which can become a hopeful candidate in the field of MA.

Fe/Co-chalcogenide-stabilized Fe3O4 nanoparticles supported MgAl-layered double hydroxide as a new magnetically separable sorbent for the simultaneous spectrophotometric determination of anionic dyes

Magnesium-aluminum layered double hydroxide (MgAl-LDH) supported on Fe3O4–SiO2 which stabilized and modified by CoS-FeS chalcogenide was prepared and characterized by FT-IR, XRD, FE-SEM, EDS and, VSM analysis. Subsequently, this prepared material was applied in a dispersive solid-phase extraction (DSPE) system for simultaneous preconcentration and determination of trace levels of disulfine blue (DSB) and bromocresol green (BCG) anionic dyes from aqueous solutions which method was followed by UV–vis spectrophotometry detection. Central composite design (CCD) was applied to optimize the contribution of operational parameters including pH, sorbent dosage, sonication extraction time, type, volume and eluent concentration on system performance. Under optimized conditions, detection and quantification limits were obtained to be 0.033 mg L−1 and 0.109 mg L−1 for DSB and 0.037 and 0.123 mg L−1 for BCG, respectively, as well as, good linearity was obtained. This novel and interesting extraction approach seem to be fast and efficient procedure for the extraction of anionic dyes from aqueous samples. The kinetics and the adsorption isotherms of dyes reveal their rapid adsorption, following a with a pseudo-first-order kinetics and Freundlich adsorption isotherm model.