Magnetic separation of green synthesized Fe3O4 nanoparticles on photocatalytic activity of methyl orange dye removal

The most frequent method of removing malignant growth-causing tones from current effluents before releasing them into water sources such as rivers, lakes, and groundwater has become standard. Traditional waste-water treatment frameworks have trouble getting rid of these contaminants. This is a unique flavonoid that uses Fe₃O₄ nanorods as photocatalytic agents to corrupt material tone in the watery stage utilizing observable light enlightenment. Green technique was used to amalgamate [email protected]₃O₄ nanorod like gems. Disappearance of the bright (UV) maintenance top at 565 nm confirmed the elimination of Methyl orange tone. After 110 min, the sensational shading disposal of Fe₃O₄ nanorod was observed to be 100%. This is due to photochemical redox process and the use of Fe₃O₄ nanorods with a high energy gap of flavonoids. The findings show that Fe₃O₄ rod-like gems manufactured using green technology are extremely valuable in the photocatalytic annihilation of hazardous contaminants.     

Improving the catalytic activity of magnetic Fe3O4/ZnO-CdO/reduced graphene oxide for ultrasonic degradation of the organic pollutants and the green oxidation of olefins

Magnetic Fe₃O₄/ZnO-CdO/reduced graphene oxide (MFZC/RGO) has been synthesized by simple hydrothermal method. The structure and morphology were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Diffuse reflectance spectroscopy (DRS), Vibrating sample magnetometer (VSM), Raman and Fourier-transform infrared spectroscopy (FTIR). MFZC/RGO was applied as catalyst in degradation of methylene blue (MB), rhodamin B (RhB) and methylorange (MO) under ultrasonic irradiation. Based on the results, excellent degradation efficiencies of MB, RhB and MO (>99%) were achieved within 10, 20 and 20 min, respectively under oxygen flow. Moreover the catalytic property of MFZC/RGO was investigated in oxidation of styrene, α-methyl styrene, cyclohexene and cyclooctene under oxygen flow. In addition, MFZC/RGO can be easily collected and separated by an external magnet. The catalyst displayed negligible loss in activity and selectivity within several successive runs due to super paramagnetism.     

Synergetic catalytic effect of rGO,Pd, Fe3O4 and PPy as a magnetically separable and recyclable nanocomposite for coupling reactions in green media

In this paper, rGO/Pd–Fe₃O₄@PPy as an efficient stable nanocomposite was synthesized. To understand the synergetic effects of rGO, Pd, Fe₃O₄ and PolyPyrrole, the performance of rGO/Pd–Fe₃O₄@PPy as a heterogeneous recyclable nanocatalyst in the green synthesis of C‐C and C‐O coupling products, as well as different conditions are studied. Synthesized rGO/Pd–Fe₃O₄@PPy was characterized by FT‐IR, XRD, FE‐SEM, EDS, TGA and AFM analysis. Best results are obtained under sonication in H₂O for C‐C coupling and by ball‐milling for C‐O coupling. The benefits of this method include: green solvents and conditions, absence of external base, low reaction times with high yield and easy work‐up method.     

Copper-based Schiff Base Complex Immobilized on Core-shell Fe3O4@SiO2 as a magnetically recyclable and highly efficient nanocatalyst for green synthesis of 2-amino-4H-chromene derivatives

Fe₃O₄-supported copper (II) Schiff-Base complex has been synthesized through post-modification with 1,3-phenylenediamine followed by further post-modification with salicylaldehyde and coordination with Cu(II) ion. The resulted Fe₃O₄@SiO₂-imine/phenoxy-Cu(II) magnetic nanoparticles (MNPs) were characterized by various techniques including SEM, TEM, XRD, XPS, EDX, VSM, FT-IR, and ICP. The catalytic activity as a magnetically recyclable heterogeneous catalyst for one-pot, three-component synthesis of 2-amino-4H-chromene derivatives was examined. The catalyst is efficient in the reaction and can be recovered by magnetic separation and recycled several times without significant loss in the catalytic activity.     

Dependence of the Nanoscale Composite Morphology of Fe3O4 Nanoparticle-Infused Lysozyme Amyloid Fibrils on Timing of Infusion: A Combined SAXS and AFM Study

Understanding the formation process and the spatial distribution of nanoparticle (NP) clusters on amyloid fibrils is an essential step for the development of NP-based methods to inhibit aggregation of amyloidal proteins or reverse the assembling trend of the proto-fibrillary complexes that prompts pathogenesis of neuro degeneration. For this, a detailed structural determination of the diverse hybrid assemblies that are forming is needed, which can be achieved by advanced X-ray scattering techniques. Using a combined solution small angle X-ray scattering (SAXS) and atomic force microscopy (AFM) approach, this study investigates the intrinsic trends of the interaction between lysozyme amyloid fibrils (LAFs) and Fe₃O₄ NPs before and after fibrillization at nanometer resolution. AFM images reveal that the number of NP clusters interacting with the lysozyme fibers does not increase significantly with NP volume concentration, suggesting a saturation in NP aggregation on the fibrillary surface. The data indicate that the number of non-adsorbed Fe₃O₄ NPs is highly dependent on the timing of NP infusion within the synthesis process. SAXS data yield access to the spatial distribution, aggregation manner and density of NP clusters on the fibrillary surfaces. Employing modern data analysis approaches, the shape and internal structural morphology of the so formed nanocomposites are revealed. The combined experimental approach suggests that while Fe₃O₄ NPs infusion does not prevent the fibril-formation, the variation of NP concentration and size at different stages of the fibrillization process can impose a pronounced impact on the superficial and internal structural morphologies of these nanocomposites. These findings may be applicable in devising advanced therapeutic treatments for neurodegenerative diseases and designing novel bio-inorganic magnetic devices. Our results further demonstrate that modern X-ray methods give access to the structure of—and insight into the formation process of—biological–inorganic hybrid structures in solution.     

Synthesis of the ZnO-Ni0.5Zn0.5Fe2O4-Fe2O3 magnetic catalyst in pilot-scale by combustion reaction and its application on the biodiesel production process from oil residual

A magnetic catalyst with composition ZnO-Ni_0.5Zn_0.5Fe₂O₄-Fe₂O₃ was synthesized by a combustion reaction on a pilot-scale and applied in the conversion of residual oil into biodiesel by simultaneous transesterification and esterification reactions (TES). For that, statistical analysis of the factors that influence the process (catalyst concentration, alcoholic route, and temperature) was evaluated by 2³ factorial experimental design. The ZnO-Ni_0.5Zn_0.5Fe₂O₄-Fe₂O₃ magnetic catalyst was characterized in terms of the structure, morphology, magnetic, TPD-NH₃ acidity analysis and catalytic properties. The results indicate the formation of a catalyst with a surface area of 52.9 m²g⁻¹, and density of the sample was 4.8 g/cm³ which is consisted of a mixture of the phases containing 55.87% Fe₂O₃, 36.96% Ni_0.5Zn_0.5Fe₂O₄, and 7.16% ZnO. The magnetic characterization indicated that the synthesized catalyst is ferromagnetic with magnetization 6.12 emu/g and coercive field of 5.3 G. In the TES reactions, the residual oil was active showing conversion to 96.16% ethyl esters and with a long useful life maintaining sustained activity after two consecutive reuse cycles with the conversion of 95.27%, 93.07% and 76.93%, respectively. The experimental design was significant and presented a 95% reliability level. The statistical analysis identified (+1) and (−1) as higher and lower level variables, respectively. The amount of catalyst used was equal to 5%, at 200 °C in methyl alcohol (alcoholic route). In summary, a new catalyst composed of a mixture of magnetically active phases was developed and successfully applied in biodiesel’s synthesis from residual oil. Undoubtedly these results have a positive and significant impact on the environment and to society as a whole.     

Effect of lattice strain on structure,morphology, electrical conductivity and magneto-optical and catalytic properties of Ni-doped Mn3O4 nano-crystallites synthesized by microwave route

Ni-doped Mn₃O₄ nanoparticles (NPs) were synthesized by a simple one-pot microwave combustion procedure utilizing urea as a fuel. X-ray diffraction, transmission electron microscopy (TEM), diffuse reflectance spectroscopy, Photoluminescence spectra, and vibrating sample magnetometer. The particle size and the crystalline size measured from the HR-TEM monographs and XRD study suggest the similarity of the data collected from these two measurements. Photoluminescence (PL) spectra demonstrated increased luminescence amplitude with increased Ni concentration. Thus, the present study determines the time required for 4-nitrophenol yellow to colorless by Ni-doped Mn₃O₄ and Mn₃O₄ samples.     

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%.     

Anchoring Ni (II) on Fe3O4@tryptophan: A recyclable,green and extremely efficient magnetic nanocatalyst for one‐pot synthesis of 5‐substituted 1H‐tetrazoles and chemoselective oxidation of sulfides and thiols

A green, novel and extremely efficient nanocatalyst was successfully synthesized by the immobilization of Ni as a transition metal on Fe₃O₄ nanoparticles coated with tryptophan. This nanostructured material was characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, inductively coupled plasma optical emission spectroscopy, vibrating sample magnetometry and X‐ray diffraction. The prepared nanocatalyst was applied for the oxidation of sulfides, oxidative coupling of thiols and synthesis of 5‐substituted 1H‐tetrazoles. The use of non‐toxic, green and inexpensive materials, easy separation of magnetic nanoparticles from a reaction mixture using a magnetic field, efficient and one‐pot synthesis, and high yields of products are the most important advantages of this nanocatalyst.     

Synthesis and characterization of sulfamic acid supported on Fe3O4 nanoparticles: A green,versatile and magnetically separable acidic catalyst for oxidation reactions and Knoevenagel condensation

Sulfamic acid immobilized on diethylenetriamine functionalized Fe₃O₄ nanoparticles (SA‐DETA‐Fe₃O₄) was successfully prepared and characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), vibrating sample magnetometer (VSM), thermo gravimetric analysis (TGA), X‐Ray diffraction (XRD) and scanning electron microscopy (SEM). The sulfamic acid was found as a magnetically separable and highly active catalyst for the oxidative coupling thiols, oxidation of sulfides. Furthermore, the SA‐DETA‐Fe₃O₄ showed the high catalytic activity in Knoevenagel condensation of aromatic aldehydes with active methylene compounds (malononitrile and ethyl cynoacetate). The nanosolid catalyst could be easily recovered by a simple magnetic separation and reused for many cycles without deterioration in catalytic activity.     

The effect of impurities Pb,Bi, and PbO on erosion properties of Lead-Bismuth Eutectic alloy on Fe3O4 oxide film by first principle calculations

The first-principle calculation was performed to study the effect of impurities Pb, Bi, and PbO on erosion properties of liquid lead-bismuth eutectic alloy on the metal oxide (Fe₃O₄) and its surfaces. We found that whether in the bulk or on the surface of Fe₃O₄ the formation energy by substitution of Fe with Bi is slightly larger than that with Pb substitution and the formation energy by substitution of Fe with PbO is much larger than those with Pb and Bi, indicating that PbO has weaker corrosion potential than Pb/Bi. The calculation results show that a tetrahedral site in Fe₃O₄ should be the weakest position where Fe₃O₄ is attacked by these exotic impurities. The corrosion process on the oxide film will be initialized at that position. It can be seen that for the doping case the dissociation energy of Fe atom in the (110) surface has the smallest value, a medium value in (100) surface, and the largest value in (111) surface. Correspondingly, the corrosion resistance of doping Fe₃O₄ film in (110) surface is the weakest one among these surfaces. For the doping-free case, the (100) surface has the weakest corrosion resistance. By comparing the doping case with no-doping case it can be seen that the impurities of Pb, Bi, and PbO will weaken the corrosion resistance of Fe₃O₄ film further. The doping has a negative impact on the stability of the structure and on the corrosion resistance of Fe₃O₄ film. From present results, it is also seen that the replacement of Fe in Fe₃O₄ by multiple impurities is more likely to occur than the replacement of only single impurity.     

Dendrimer‐encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe3O4@SiO2 nanoparticles as a novel recyclable catalyst for N‐arylation of nitrogen heterocycles and green synthesis of 5‐substituted 1H‐tetrazoles

In this study, dendrimer‐encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe₃O₄@SiO₂ nanoparticles were prepared via a multistep‐synthesis. Then, the synthesized composite was fully characterized by various techniques such as fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), dynamic light scattering (DLS), UV‐vis spectroscopy, energy dispersive X‐ray analysis (EDX), thermogravimetric analysis (TGA) and vibration sample magnetometer (VSM). From the information gained by FE‐SEM and TEM studies it can be inferred that the particles are mostly spherical in shape and have an average size of 50 nm. Also, the amount of Cu is determined to be 0.51 mmol/g in the catalyst by inductively coupled plasma (ICP) analyzer. This magnetic nano‐compound has been successfully applied as a highly efficient, magnetically recoverable and stable catalyst for N‐arylation of nitrogen heterocycles with aryl halides (I, Br) and arylboronic acids without using external ligands or additives. The catalyst was also employed in a one‐pot, three‐component reaction for the efficient and green synthesis of 5‐substituted 1H‐tetrazoles using various aldehydes, hydroxylamine hydrochloride and sodium azide in water. The magnetic catalyst can be easily separated by an external magnet bar and is recycled seven times without significant loss of its activity.     

Sulfamic acid heterogenized on functionalized magnetic Fe3O4 nanoparticles with diaminoglyoxime as a green,efficient and reusable catalyst for one‐pot synthesis of substituted pyrroles in aqueous phase

Surface functionalization of magnetic nanoparticles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. We have conveniently loaded sulfonic acid groups on amino‐functionalized Fe₃O₄ nanoparticles affording sulfamic acid‐functionalized magnetic Fe₃O₄ nanoparticles (MNPs/DAG‐SO₃H) as an active and stable magnetically separable acidic nanocatalyst, which was characterized using X‐ray diffraction, Fourier transform infrared and energy‐dispersive X‐ray spectroscopies, scanning and transmission electron microscopies, vibrating sample magnetometry and elemental analysis. The catalytic activity of MNPs/DAG‐SO₃H was probed through one‐pot synthesis of N‐substituted pyrroles from γ‐diketones and primary amines in aqueous phase at room temperature. The heterogeneous catalyst could be recovered easily by applying an external magnet device and reused many times without significant loss of its catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Catalytic reduction of hazardous acid orange 10 dye by BiVO4/TiO2 nanocrystalline heterojunction and influence of aeration,FeSO4, H2O2 and FeCl3 on removal efficiency: A novel and environmentally friendly process

Bismuth vanadate in combination with titanium dioxide were synthesized by hydrothermal method and its photocatalytic activity was investigated under visible light irradiation for acid orange 10 (AO10) dye removal. The 10% BiVO₄/TiO₂ showed the highest catalytic activity in comparison with 20, 30, 40 and 50% BiVO₄/TiO₂ ratios. The removal of AO10 azo dye in aqueous solutions was studied in laboratory-scale experiments using 25 removal processes and their removal efficiencieswere evaluated, separately. The results showed that the amount of de-colorization for each oxidation process is completely different. The order of the investigated processes in removing the dye after 90 min is as follows: LED < TiO₂ < BiVO₄ < 10% BT/without LED < BiVO₄/ LED < 50% BT < 40% BT < 30% BT < 20% BT < UV/H₂O₂ < 10% BT < 5a-10 %BT < 5F-10 %BT < 10a-10 %BT < 50F-10 %BT < 20a-10 %BT < 10F-10 %BT < 20F-10 %BT < 20H_-10 %BT < 40H-10 %BT < 50H_-10 %BT < 20a-20F-10 %BT < 20a-20F-50H_-10 %BT. Among the above processes, 20a-20F-50H-10 %BT had the best removal performance and can be suggested for using in real conditions. Coagulation/precipitation process was done using 5 mg/L of FeCl₃ as post-treatment reaching efficiency of 100% in the studied system.     

The solvent‐free synthesis of polysubstituted pyrroles by a reusable copper Schiff base complex immobilized on silica coated Fe3O4, and DNA binding study of one resulting derivative as a potential anticancer drug

We demonstrate herein the synthesis of a new copper Schiff base complex immobilized on silica‐coated Fe₃O₄ nanoparticles. The structure and composition of this magnetic nanocatalyst were analyzed using Fourier transform infrared (FT‐IR), X‐ray powder diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), energy dispersive X‐ray (EDX) and inductively coupled plasma atomic emission spectroscopy (ICP‐AES). This nanocomposite was found to be an efficient nanocatalyst for the synthesis of polysubstituted pyrrole derivatives and the products were isolated with high turnover number (TON) and high to excellent yields. Among the new synthesized polysubstituted pyrrole derivatives, we explored the first computational and experimental binding study of methyl 1‐benzyl‐4‐(furan‐2‐yl)‐2‐methyl‐1H‐pyrrole‐3‐carboxylate (SP‐10) with calf thymus deoxyribonucleic acid (ct‐DNA), suggesting their application as potential anticancer activity. In addition, the binding modes of SP‐10 with DNA and human serum albumin (HSA) were verified by molecular docking technique.     

Magnetic solid‐phase extraction based on a polydopamine‐coated Fe3O4 nanoparticles absorbent for the determination of bisphenol A,tetrabromobisphenol A, 2,4,6‐tribromophenol,and (S)‐1,1’‐bi‐2‐naphthol in environmental waters by HPLC

Polydopamine‐coated Fe₃O₄ magnetic nanoparticles synthesized through a facile solvothermal reaction and the self‐polymerization of dopamine have been employed as a magnetic solid‐phase extraction sorbent to enrich four phenolic compounds, bisphenol A, tetrabromobisphenol A, (S)‐1,1′‐bi‐2‐naphthol and 2,4,6‐tribromophenol, from environmental waters followed by high‐performance liquid chromatographic detection. Various parameters of the extraction were optimized, including the pH of the sample matrix, the amount of polydopamine‐coated Fe₃O₄ sorbent, the adsorption time, the enrichment factor of analytes, the elution solvent, and the reusability of the nanoparticles sorbent. The recoveries of these phenols in spiked water samples were 62.0–112.0% with relative standard deviations of 0.8–7.7%, indicating the good reliability of the magnetic solid‐phase extraction with high‐performance liquid chromatography method. In addition, the extraction characteristics of the magnetic polydopamine‐coated Fe₃O₄ nanoparticles were elucidated comprehensively. It is found that there are hydrophobic, π–π stacking and hydrogen bonding interactions between phenols and more dispersible polydopamine‐coated Fe₃O₄ in water, among which hydrophobic interaction dominates the magnetic solid‐phase extraction performance.