Fe3O4 SiO2 Research Articles

Deciphering the catalytic activity of nickel anchored on Fe3O4@SiO2@3-CPMS@L as a magnetically recoverable nanocatalyst for the efficacious reduction of 4-nitrophenol, nitrobenzene, and methyl orange

In this paper, a versatile heterogeneous nanocatalyst was fabricated employing a self-assembly technique. To commence, Fe3O4 MNPs were coated with a thin layer of SiO2 using the stobbers method. Subsequently, the surface was further functionalized with 3-CPMS, followed by a reaction with a Schiff base. Finally, nickel NPs were deposited on the surface through in situ deposition, forming the Fe3O4@SiO2@3-CPMS@L-Ni magnetic nanocatalyst. The architecture of this magnetic nanocatalyst was meticulously characterized through an array of sophisticated techniques: XRD, FT-IR, SEM, TEM, BET and VSM. The XRD diffraction pattern confirmed the presence of Fe3O4 MNPs, SiO2, and Ni peaks, providing evidence for successful synthesis. Moreover, the successful functionalization with a Schiff base was demonstrated by the presence of an azomethane peak in the FTIR spectra of the synthesized nanocatalyst. The fabricated nanocatalyst was adeptly utilized for the reduction of 4-NP, NB, and MO demonstrating a remarkably elevated rate of catalytic efficacy. Moreover, this catalyst was effortlessly retrievable through the application of an external magnet, and it maintained its catalytic prowess across at least six consecutive cycles. The utilization of water as an environmentally friendly solvent, coupled with the utilization of abundant and cost-effective nickel catalyst instead of the costly Pd or Pt catalysts, along with the successful recovery and scalability of the catalyst, render this method highly advantageous from both environmental and economic perspectives for the reduction of 4-NP, NB, and MO.

Studying the structural, thermal, mechanical, and dielectric features of PVA/iron oxide@SiO2 polymer nanocomposites for electrical applications

Fe3O4@SiO2 (FS) nanocomposite was synthesized through the co-precipitation method and utilized as a filler material in the polyvinyl alcohol (PVA) matrix to obtain PVA/iron oxide@silica Fe3O4@SiO2 (PFS) films. This study presents the synthesis and characterization of flexible polymer nanocomposites comprising polyvinyl alcohol (PVA) matrices embedded with iron oxide @ silica. Through the analysis of the composite, we observed a significant enhancement in the thermal stability of the nanocomposites with increasing Fe3O4@SiO2 content. X-ray photoelectron spectroscopy (XPS) spectra have been used to provide more information about the chemical state and electronic structure of the polymer film. Dielectric spectroscopy revealed notable improvements in electrical properties, including increased real electric modulus and permittivity. Mechanical investigation showed an improvement in the tensile strength, meanwhile, Young's modulus has improved from 341.2 to 1789.8 MPa, indicating that (PVA) and FS successfully complexed and interacted strongly. These findings underscore the potential of these nanocomposites for high-performance applications in energy storage devices and other fields requiring robust dielectric materials.

Technoeconomic and environmental impact assessment of industrial scale biodiesel production process from algal oil using a reusable basic ionic liquid magnetic nanocatalyst

A unique magnetically reusable basic ionic liquid nanocatalyst was designed to convert algal oil into biodiesel. The imidazolium-based basic ionic liquid (BIL) was immobilized onto the magnetic nanocomposite (Fe3O4-SiO2), resulting in Fe3O4-SiO2-BIL nanocatalyst with notable properties of large surface area (21.963 m2/g), high saturation magnetization (28.78 emu/g) and high thermal stability. The nanocatalyst effectively facilitated algal oil transesterification with 96.94 % biodiesel yield under methanol: oil ratio of 8.58:1 and a catalyst dosage of 4.59 % at 60.60 °C for 87.42 min. The transesterification reaction proceeded with pseudo-first-order kinetics, featuring a relatively low activation energy. The nanocatalyst showed excellent reusability for eight recycles. A techno-economic analysis demonstrated that industrial-scale biodiesel production from algal feedstock was economically viable with a minimum payback of 2.25 years. The environmental analysis revealed a low carbon footprint with the emission of 0.074 kg CO2 per kg of biodiesel produced. This research presents a sustainable approach for biodiesel production from algal feedstock facilitated by Fe3O4–SiO2–BIL nanocatalyst, offering both environmental and economic benefits.

Novel hybrid chemical magnetorheological fluid for polishing Ti–6Al–4V alloy

ABSTRACT This study presents a highly efficient chemical and magnetorheological fluid (C-MRF) hybrid polishing process established by using an eco-friendly slurry of malic acid, Fe3O4–SiO2 abrasive particles, and hydrogen peroxide (H2O2) as an oxidant, all mixed with purified water, highlighting its efficacy in a wide range of polishing applications. Herein, the polishing processes of Ti–6Al–4V alloy utilizing C-MRF with on Fe3O4–SiO2 abrasives are detailed, and the polishing performance is assessed by investigating the influence of oxidizing agent H2O2 and acid malic to the surface finish of the Ti–6Al–4V alloy. The linear variable magnetic field by improved Halbach array was proposed to improve the material removal rate and surface quality and create a polishing process with a highly efficient magnetic field source. Single-factor and orthogonal experimental analysis methods are applied to provide the technological parameters factors with varying influences on surface quality and material removal ability.

Process design, kinetics, simulation, and techno-economic analysis of biodiesel production from Pongamia pinnata seed oil using a magnetically recyclable acidic ionic liquid catalyst

A magnetically recyclable polymeric acidic ionic liquid nanocatalyst was fabricated in response to the demand for economical and eco-friendly one-pot conversion of inexpensive oils to biodiesel. To achieve this, Fe3O4–SiO2 nanocomposites with Fe3O4 as the core and SiO2 as the shell were prepared, and polymeric acidic ionic liquid (PAIL) was grafted over the core–shell nanocomposite (Fe3O4-SiO2) to produce Fe3O4–SiO2–PAIL nanocatalyst. The characterization results demonstrated that Fe3O4–SiO2–PAIL nanocatalyst had a strong saturation magnetization of 19.16 emu/g, a large surface area of 13.067 m2/g, and a high acid loading of 6.1 mmol/g. The Fe3O4–SiO2–PAIL was used as a heterogeneous catalyst to transesterify Pongamia pinnata seed oil (PPO) into fatty acid methyl esters (FAME). The biodiesel yield was 94.89% under optimized reaction conditions of 6.14 % (w/w) catalyst loading, methanol:oil molar ratio of 12:12, 57.37 °C, and 1.67 h. The produced FAME complied with the ASTM specifications for biodiesel. The transesterification reaction exhibited a low activation energy of 28.298 KJ/mol with pseudo-first-order kinetics. The positive values of ΔH° and ΔG° indicated that the transesterification reaction was endothermic, endergonic, and non-spontaneous. The negative value of ΔS° illustrated that the reaction is less disordered. Furthermore, the reusability studies of the heterogeneous nanocatalyst was investigated. The Fe3O4-SiO2-PAIL nanocatalyst was successfully retrieved swiftly by magnetic force, with no discernible mass loss, and employed at least six additional times without significantly losing its catalytic activity. The techno-economic analysis was executed to investigate the technical and economical feasibility of 15 metric tonne/batch biodiesel production from Pongamia pinnata seed oil using the Fe3O4–SiO2–PAIL nanocatalyst. The economic reports demonstrated a positive NPV of 20,736,000 $/year, a gross margin of 9.41%, and a biodiesel minimum selling price of 0.926 $ with a payback period of 1.88 years. This work paves the way for the sustainable use of P. pinnata as a feedstock for biodiesel production using the Fe3O4–SiO2–PAIL nanocatalyst under specified circumstances.

Effectiveness and number of transfer units of plate heat exchanger with Fe3O4–SiO2/Water hybrid nanofluids: Experimental and artificial neural network predictions

This paper analyses the effectiveness and number of transfer units of water dispersed Fe3O4–SiO2 hybrid fluids passing via plate heat exchanger experimentally. The flow of Fe3O4–SiO2/water hybrid nanofluids in plate heat exchanger remains the laminar flow conditions. The experimental studies were carried out with particle loadings ranging from 0.2 % to 1.0 % and flow rates ranging from 0.05 kg/s to 0.1166 kg/s. The obtained results of effectiveness and number of transfer units from these experiments were predicted with artificial neural network based scaled conjugate gradient (SCG) method. Based on the chemical reaction and in-situ growth methods, the Fe3O4–SiO2 nanoparticles were prepared and then characterized using x-ray diffraction (XRD) and vibrating sample magnetometer (VSM) equipment. Water diluted hybrid nanofluids were developed and used for the experimental studies. Results from the XRD indicates that, the particle size of synthesized Fe3O4–SiO2 nanoparticles were found to be 47 nm and the results from VSM shows, the final Fe3O4–SiO2 sample contains 67.8 % of SiO2 and 32.2 % of Fe3O4. Results also indicates with an increase of volume loadings and Reynolds number, the effectiveness and number of transfer units were enhanced. The effectiveness and number of transfer units were increased by 13.23 % and 24.51 % at 1.0 % vol. of hybrid nanofluid and at a Reynolds number of 571.89, over water data. Through the SCG method, the correlation coefficient R2 for effectiveness is 0.99040, and the R2 for number of transfer units is 0.98771, respectively. New generalized equation was proposed for the evaluation of effectiveness and number of transfer units.

Experimental and support vector machine predictions of entropy generations and exergy efficiency of Fe3O4–SiO2/Water hybrid nanofluid in a plate heat exchanger

Several experiments of Fe3O4–SiO2/water hybrid nanofluids with volumetric concentrations ranging from 0.2 % to 1.0 % circulating in the cold-side of a plate heat exchanger at flow rates ranging from 0.05 kg/s to 0.1166 kg/s are performed. Under these ranges of flow rates and volumetric concentrations, the flow of Fe3O4–SiO2/water hybrid nanofluids remains laminar. The results of these experiments are predicted with support vector machine (SVM) algorithm to determine hybrid nanofluid entropy generation thermal, entropy generation frictional, and efficiency of exergy. Fe3O4–SiO2 nanomaterials was synthesized with reduction of chemicals and insitu development techniques, with XRD, FTIR and VSM instruments, characterizations were done. The SVM model gives large precision predictions of the measured data with correlations coefficients of 0.9944, 0.99798, and 0.99428 for frictional entropy generation, thermal entropy generation and exergy efficiency. At a flow rate of 0.1166 kg/s in the cold-side of PHE, the exergy efficiency is found to be 77.96 % for water (Reynolds number of 935.4) and with 1.0 vol% of Fe3O4–SiO2/water hybrid nanofluid in the cold-side of PHE, the efficiency is increased to 82.97 %, respectively. Under similar conditions of 0.1166 kg/s of flow circulation and 1.0 % vol. concentration of hybrid nanofluid, the thermal entropy generation is dropped off to 18.37 %, but the frictional entropy generation is increased by 20.97 %, compared to water, with the results that the total entropy generation drops off by 15.91 %, compared to water data. Preliminary curve-fitting correlations have been developed for the frictional entropy generation, thermal entropy generation, and exergy efficiency.

Particle size and its distribution deduced from magnetic properties of magnetite nanoparticles by the modified Langevin equation

The magnetic hysteresis curve can provide information about magnetic properties, particle size, and its distribution. For superparamagnetic materials, the characteristics of the hysteresis curve are very typical, that is, Hc is equal to zero with a certain Ms value related to particle size in the order of nanometers. Here, we report the analysis of the magnetization hysteresis curve by applying a modified Langevin equation with and without a log-normal distribution for nearly superparamagnetic Fe3O4 and Fe3O4 encapsulated by SiO2 (Fe3O4–SiO2). To study the reliability of the modified Langevin equation, we compared the particle size values obtained from fittings analysis of the modified Langevin equation with those obtained from the TEM measurement. It was found that particle size from TEM measurement for Fe3O4 and Fe3O4–SiO2 is 11 and 14 nm, respectively. These values had a very high match with the particle size obtained from fitting analysis of the modified Langevin equation with or without a log-normal distribution, which is 12.6 and 12.9 nm for Fe3O4 and 13.8 and 14.5 nm for Fe3O4–SiO2, respectively. The fitting results of the modified Langevin equation with a log-normal distribution showed a value closer to the measurement results. By using the modified Langevin equation with a log-normal distribution, it was also obtained that the probability density function for Fe3O4 was 20.69% and that for Fe3O4–SiO2 was 0.55%. It was concluded that the modified Langevin equation with and without log-normal distribution was able to be used to obtain the particle size and its distribution for nearly superparamagnetic samples.

Fabrication of recyclable magnetic Fe3O4–SiO2–Cu2O/Cu core–shell nano-catalyst for high-efficient reduction of aromatic nitro compound

Fabrication of recyclable magnetic Fe3O4–SiO2–Cu2O/Cu core–shell nano-catalyst for high-efficient reduction of aromatic nitro compound

Fe3O4 nanoparticles and Fe3O4 @SiO2 core-shell: synthesize, structural, morphological, linear, and nonlinear optical properties

Magnetic iron oxide (Fe3O4) and Fe3O4 @SiO2 core-shell were prepared via co-precipitation and modified Stöber methods. Structural, morphological, and optical properties were examined using XRD, FTIR, and UV–visible spectrophotometer. This study used three different methods to deduce the studied nanoparticles' optical gap energy: (i) the Tauc model, (ii) the absorption spectrum fitting model, and (iii) the derivation of the absorption spectrum fitting model. The calculated values of gap energy of Fe3O4 @SiO2 NPs by the three different methods are higher than the corresponding values of Fe3O4 NPs and SiO2 NPs. The optical oscillator strength (f) of Fe3O4 @ SiO2 NPs has the greatest value (24.4 eV2) compared to the others. The values of the high-frequency dielectric constant (ε∞) are greater than the square of the infinite wavelength refractive index (n∞2). Therefore, the free charge-carrier contribution during the incidence of photon energy on the tested NPs significantly affects the polarization. The high value of the third-order nonlinear optical susceptibility (χ(3)) of Fe3O4 @ SiO2 NPs can candidate them to be applied in the applications of nonlinear optics as power limiters. The nonlinear absorption coefficient (βc) increased by increasing the incident energy and has a maximum value in a range of energies from 3.25 eV to 5 eV, for all the samples. The synthesized Fe3O4 @SiO2 core-shell nanomaterials with enhanced optical parameters is considered as a suitable candidate in nonlinear optical applications.

Effect of the Structure of Magnetic Nanocomposite Adsorbents on the Lysozyme Separation Efficiency.

In this study, we prepared various anionic magnetic adsorbents through the carboxyl functionalization of core/shell-structured Fe3O4/SiO2 (FS) particles by either succinic anhydride (FSC), low-molecular-weight (MW 1800) polyacrylic acid (PAA) (FSP1), or high-molecular-weight (MW 100,000) PAA (FSP2), and then, investigated the effect of the structure of adsorbents and operational parameters on their performance for the lysozyme separation. The type and size of functional molecules have significant effects on the surface concentration of functional carboxyl groups onto the adsorbent particles (increase in the order of FSP2 > FSP1 > FSC), and consequently on the adsorption efficiency (AE) (∼100, 98, and 62%, respectively) and adsorption capacity (AC) (∼1000, 980, and 621 mg·g-1, respectively) of the adsorbents. However, the loss of the antibacterial activity of separated lysozyme molecules due to the molecular conformational change increased in the order of FSP2 > FSP1 = FSC, as compared to the free lysozyme. The application of basic buffer solutions for the elution of adsorbed enzyme molecules resulted in more adverse effects on the enzyme activity. The obtained results recommend that FSP1 can be used as a suitable anionic adsorbent for the isolation of positively charged proteins, owing to its high adsorption capacity, excellent reusability, and structural stability, as well as the high purity, structural stability, and activity recovery of the isolated proteins.

Influence of oxides on the formation of self-lubricating layer and anti-wear performance during sliding

Oxides are the key roles on the formation of self-lubricating layer (SLL) with anti-wear performance. In present study, dry sliding wear tests of 00Cr13Ni4Mo steel were performed to investigate the influence of oxides on SLL. The formation of SLL with different oxides was comparatively analyzed by the cross-sectional and surface morphologies. Mechanism of oxides on the integrity of SLL and anti-wear performance is discussed. It is confirmed that Cr-oxide, Fe3O4 and suitable SiO2 are the key to endow SLL with good self-lubricating performance while FeO, Fe2O3 and excessive SiO2 are opposite, good integrity of SLL is the prerequisite for anti-wear.

Basic ionic liquid grafted on magnetic nanoparticles: An efficient and highly active recyclable catalyst for the synthesis of β-nitroalcohols and 4H-benzo[b]pyrans

In this study, we have synthesized Fe3O4@SiO2 (FS) immobilized 1,4-diazabicyclo[2.2.2] octane (DABCO) based-basic ionic liquid functionalized magnetic nanoparticles. The synthesized nanocomposite was characterized by various physicochemical and morphological techniques such as - FTIR, Powder-XRD, VSM, BET, CHN, TEM and SEM-EDX. Its application was checked as an active and highly efficient green catalyst by utilizing it in the synthesis of various 4H-benzo[b]pyran and β-nitroalcohol derivatives. The prepared heterogeneous catalyst was found to be thermally stable and highly cost-effective for the base-promoted organic transformation reactions producing excellent yields in short reaction times. In addition to this, the prepared magnetic nanocomposite could be readily recovered by applying a magnetic field and can be recycled up to eight catalytic cycles without any noteworthy loss in its performance.

Enhanced Acoustic Droplet Vaporization through the Active Magnetic Accumulation of Drug-Loaded Magnetic Particle-Encapsulated Nanodroplets (MPE-NDs) in Cancer Therapy.

The application of drug-loaded nanodroplets is still limited by their insufficient accumulation owing to the enhanced permeability and retention (EPR) effect failure in cancer therapy. To overcome these limitations, we propose an alternative magnetic particle-encapsulated nanodroplet (MPE-ND) with outstanding biosafety and magnetic targeting by encapsulating fluorinated Fe3O4-SiO2 nanoparticles inside the liquid core of the nanodroplets. Meanwhile, doxorubicin (DOX) can be stably loaded into the shell through both electrostatic and hydrophobic interactions to obtain drug-loaded MPE-NDs. Both in vitro and in vivo experiments have consistently demonstrated that drug-loaded MPE-NDs can significantly increase the local drug concentration and enhance the damage of tumor tissues through acoustic droplet vaporization under a static magnetic field (eADV therapy). Histological examination reveals that eADV therapy efficiently suppresses tumor proliferation by inducing apoptosis, destroying supply vessels, and inhibiting neovascularization. Drug-loaded MPE-NDs can be expected to open a new gateway for ultrasound-triggered drug delivery and cancer treatment.

Sensitive and selective magnetic dispersive microextraction of diazinon from urine samples by molecularly imprinted polymer based on core–shell metal–organic frameworks

A core–shell magnetic metal–organic framework (Fe3O4 SiO2/ PAEDTC@ MIL- 101 (Fe)) was synthesized as the substrate and then covered with a surface molecularly imprinted polymer (MIP) layer. Next, Fe3O4 SiO2/ PAEDTC@ MIL- 101 (Fe) @ MIP was characterized by XRD, FT-IR, BET, VSM, TEM, and FE-SEM techniques and applied for selective, fast, and sensitive magnetic dispersive solid-phase microextraction (M-DµSPE) of diazinon from urine samples by the GC- FID detection method. The key experimental variables affecting M-DµSPE were studied and optimized by central composite design (CCD). Under optimum conditions (5 mL; sample at pH: 7.0, the mass of solid sorbent; 6 mg, extraction time; 4 min, acetonitrile as an eluent solvent; 1.5 mL, and desorption time; 3 min, and then reconstituted with 100 µL of methanol), the proposed method exhibits high sensitivity with limits of detection and quantification of 0.005 and 0.017 ng mL−1, respectively. Excellent extraction recovery (98.5 %), wide linearity range (0.02–200000 ng mL−1, R2 > 0.992), high enrichment factors (47–53), and satisfactory precision (<6.3 % RSD) were achieved. The MIP- MOF@ M-DµSPE -GC-FID method can be used with high precision and wide linearity to extract and analyze trace levels of diazinon in real urine samples.

Fe3O4–SiO2–graphene oxide–amino acid ionic liquid magnetic solid-phase extraction combined with inductively coupled plasma optical emission spectrometry for speciation of Cr(iii) and Cr(vi) in environmental water

This developed method, based on the combination of functionalized Fe3O4–SiO2–GO–AAIL and ICP-OES, is capable of remarkable selectivity towards Cr(iii).

Direct Synthesis of a Regenerative CaO–Fe3O4–SiO2 Composite Adsorbent from Converter Slag for CO2 Capture Applications

Direct Synthesis of a Regenerative CaO–Fe₃O₄–SiO₂ Composite Adsorbent from Converter Slag for CO₂ Capture Applications

Fe3O4–SiO2–Bi2O3-catalyzed One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives Under Solvent-Free Conditions

Fe3O4–SiO2–Bi2O3-catalyzed One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives Under Solvent-Free Conditions

Photocatalytic-Fenton Process under Simulated Solar Radiation Promoted by a Suitable Catalyst Selection

Considering water scarcity, photo-based processes have been presented as a depollution technique, which should be optimized in order to be applied in the future. For that, the addition of an active photocatalyst and the usage of solar radiation are mandatory steps. Thus, Fe3O4–SiO2–TiO2 was synthesized, and its performance was evaluated using simulated solar radiation and methylene blue as a model pollutant. Under optimal conditions, 86% degradation was attained in 1 h. These results were compared to recent published data, and the better performance can be attributed to both the operational conditions selection and the higher photocatalyst activity. Indeed, Fe3O4–SiO2–TiO2 was physico-chemically characterized with techniques such as XRD, N2 isotherms, spectrophotometry, FTIR, electrochemical assays and TEM.

A new insight into the separation of oil from oil/water emulsion by Fe3O4–SiO2 nanoparticles

Nanofluids have shown their potential in the oil recovery process through surface modification. Due to their surface characteristics, they can apply to improve the oil production from reservoirs by enabling different enhanced recovery mechanisms. The preparation and development of the Fe3O4@SiO2 nanoparticles for the oil recovery process is an innovative and novel approach that influences the oil generation from reservoirs. The performance of the Fe3O4@SiO2 and the other nanofluids (seawater, Fe3O4, and SiO2) in the enhanced oil recovery process is assessed and compared with other flooding scenarios. The Fe3O4@SiO2 NPs achieved the highest oil production rate of 90.2% while Fe3O4 and SiO2 NPs achieved 70.8% and 55.3%, respectively. In contrast, the value achieved for the seawater injection was 76.5%. For the oil recovery process, the Fe3O4 was applied for the inhibition (i.e., decrease) of oil sedimentation, and the SiO2 NPs were applied for wettability alteration and IFT reduction. The experimental results showed that the produced Fe3O4@SiO2 NPs improved the oil recovery rates (90.2%) as well as the synergetic impact of the developed NPs by initiating several mechanisms corresponding to the use of the separate NPs in the micromodel. Moreover, the results exhibited that the reservoir conditions are a crucial function for increasing the oil recovery rates, improving the emulsion stability, and acts as a substantial step for the oil recovery method that applies this particular technique.