Fe3O4 Composites Research Articles

Mesoporous α‑Fe2O3 nanostructures decorated with perovskite Cs3Bi2Br9 quantum dots as an S-scheme photocatalyst for efficient charge transfer and CO2 conversion

In view of the greenhouse effect caused by excessive CO2 emission in the atmosphere, the efficient capture and conversion of CO2 to chemical feedstock is imminent. Herein, a novel Cs3Bi2Br9/α‑Fe2O3 (CBB/α‑Fe2O3) composite was constructed by decorating lead-free perovskite Cs3Bi2Br9 quantum dots (QDs) on the pores of mesoporous α‑Fe2O3 nanostructures. The developed CBB/α‑Fe2O3 composite possesses bifunctional advantages for both the efficient capture and conversion of CO2, with a CO production yield of 84.12 μmol g−1h−1 for the optimized sample. Experimental results and theoretical predictions indicate that the electrons transfer via an S-scheme route in the CBB/α‑Fe2O3 composite, which not only boosts the charge separation but also retains the strong reduction ability of Cs3Bi2Br9. By combination of in-situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) with theoretical calculations, the mechanism of the photocatalytic CO2 reduction over the CBB/α‑Fe2O3 composite was explored in depth. This study opens a new avenue for the exploitation of photocatalysts with high CO2 capture ability and conversion efficiency.

Microstructure analysis of Fe3O4/Polypyrrole composite synthesized by Sol-Gel method

The composite is a material that is very important in inserting nanoparticles that act as fillers in a matrix. The filler used in this study is Fe3O4 and the matrix used as a polymer is Polypyrrole (PPy). This research aims to analyze the microstructure of Fe3O4 /PPy composite synthesized by sol-gel method. This research was conducted by varying the composition of Fe3O4:PPy including 30%, 40%, 50%, 60%, and 70% w/w. The sample was characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). The results of the FTIR characterization, it was found that the Fe3O4 /Polypyrrole has functional groups O-H, C≡C and C=C. The results of SEM characterization, the particle sizes of each variation composition of Fe3O4:PPy 30%, 40%, 50%, and 70% w/w are 3µm, 3.1µm, 4µm, and 4.5µm, respectively. Based on the results of the study, the greater the composition of the polypyrrole, the greater the particle size.

Facile synthesis of Fe3O4 ultrathin layer coated Fe2O3 composite anode for enhanced lithium-ion storage

Fe2O3 has been considered as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, its sluggish charge transfer resulting from the poor electrical conductivity severely limits the electrochemical performance. In this work, an ultrathin Fe3O4 layer-coated Fe2O3 composite was fabricated through a facile one-step hydrothermal method with hydrazine hydrate as the reductant in an alkaline environment. Upon use as the anode for LIBS, the as-resulted Fe2O3@Fe3O4 composite achieves a high specific capacity of 1539.5 mA h g−1 at a current density of 100 mA g−1 and simultaneously maintains a high discharge capacity of 707.8 mAh g−1 after 800 cycles at 1000 mA g−1, outperforming the commercial Fe2O3 sample. Electrochemical characterizations reveal that the improved electrochemical performance can be attributed to the combined effects of higher theoretical specific capacity of Fe2O3 and superior electrical conductivity of Fe3O4.

A Study on Characteristics of Brake Pad Composite Materials by Varying the Composition of Epoxy, Rice Husk, Al2O3, and Fe2O3

The use of composite materials in brake pads is becoming increasingly popular due to their high-performance characteristics, including good thermal stability, high wear resistance, and low noise generation. However, the development of new composite materials that offer even better performance is still an ongoing research area. In this study, the composite was made by hand layup method using epoxy resin as matrix material, with rice husk, Al2O3, and Fe2O3 as reinforcing materials. The composition of the composites was varied by changing the percentage of the reinforcement materials. The composites were then subjected to several characterization tests, including density, hardness, flexural strength, thermal analysis, Scanning Electron Microscopy (SEM), TGA/DSC, and wear testing. The test results showed that additional reinforcement materials to the epoxy resin matrix improved the mechanical properties of the composites. Overall, the study demonstrates that a hand layup method is a viable approach for preparing brake pad composite materials and that the addition of rice husk, Al2O3, and Fe2O3 can improve the mechanical properties of the composites. The best properties produced in this research were found in one of the specimens which used epoxy, rice husk, Al2O3, and Fe2O3 with a composition of 50 wt.%, 20 wt.%, 15 wt.%, and 15 wt.%. However, the addition of rice husk also provides wear resistance and thermal stability. This study contributes to the Sustainable Development Goals (SDGs) by advancing innovation, promoting sustainability, and reducing emissions in automotive industry applications.

Fluorinated-Polyether-Grafted Graphene-Oxide Magnetic Composite Material for Oil–Water Separation

In this study, a new type of highly efficient and recyclable magnetic-fluorine-containing polyether composite demulsifier (Fe3O4@G-F) was synthesized by the solvothermal method to solve the demulsification problem of oil–water emulsion. Fe3O4@G-F was successfully prepared by grafting fluorinated polyether onto Fe3O4 and graphene-oxide composites. Fe3O4@G-F was characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Taking the self-made crude-oil emulsion as the experimental object, the demulsification mechanism of the demulsifier and the influence of external factors, such as the temperature and pH value, on the demulsification performance of the demulsifier are discussed. The results show that the demulsification efficiency of the Fe3O4@G-F emulsion can reach 91.38% within 30 min at a demulsifier dosage of 750 mg/L, pH of 6, and a demulsification temperature of 60 °C. In neutral and acidic environments, the demulsification rate of the demulsifier is more than 90%. In addition, Fe3O4@G-F has been proven to have good magnetic effects. Under the action of an external magnetic field, Fe3O4@G-F can be recycled and reused in a two-phase system four times, and the demulsification efficiency is higher than 70%. This magnetic nanoparticle demulsifier has broad application prospects for various industrial and environmental processes in an energy-saving manner.

Construction of β-cyclodextrin modified Fe3O4 composites with enhanced peroxymonosulfate activation towards efficient degradation of norfloxacin

In the current research study, β-cyclodextrin modified Fe3O4 (β-CD@Fe3O4) superparamagnetic composite materials were synthesized using co-precipitation and ultrasonication methods, with β-CD acting as a coating material. The as-prepared material was employed as a heterogeneous catalyst for the activation of peroxymonosulfate (PMS) for the removal of norfloxacin (NOR). The catalytic activities of bare Fe3O4, β-CD@Fe3O4 composites, and the β-CD@Fe3O4/PMS system were compared under various parameters. Results revealed that the β-CD@Fe3O4/PMS exhibited higher catalytic activities, and a removal efficiency of 99.12% with a rate constant of 0.1576 min−1 was achieved in 30 min under optimum conditions ([catalyst] = 0.4 g/L, [PMS] = 4.0 mM, [NOR] = 30 mg/L, pH = 7.0). In particular, the larger surface area of β-CD@Fe3O4 (120 m2g−1) and the presence of additional reactive sites accelerated the activation of PMS in comparison to bare Fe3O4 (70 m2g−1) and thereby promoted the mineralization of NOR. The impact of various pivotal factors on NOR abatement was also studied. Scavenging results and the EPR technique revealed that the SO4•−, •OH, and O2•−radicals participated in the removal of NOR in the β-CD@Fe3O4/PMS system. The Fe3+/Fe2+/Fe3+ redox cycle in β-CD@Fe3O4 is used for the activation of PMS and generates radicles. The reusability results show excellent stability of the catalyst material, and a loss of 4.35% was observed after four cycles. The results revealed that the β-CD@Fe3O4 composites can activate PMS and have potential for the degradation of various pollutants from the environment.

Enhanced microwave absorption properties of magnetite nanoparticles decorated multi walled carbon nanotubes loaded polyaniline/polyvinyl alcohol nanocomposites

AbstractElectromagnetic radiation interference (EMI) or pollution is increased significantly in proportion to the expansion of electronic and communication industries, which lead to the disturbance of the functioning of electronic gadgets and medical equipments, in addition to the human health damage. The Microwave absorbing (MA) composite comprised of polyvinyl alcohol (PVA), polyaniline (PANI), carbon nanotube (MWCNT) and iron oxide (Fe3O4) has been developed with various proportions, denoted as PVA/PANI/MWCNT/Fe3O4 (1%, 3%, 5%). Fe3O4 was prepared using a hydrothermal method, and PVA/PANI/MWCNT/Fe3O4 (1%, 3%, 5%) nanocomposites was made by solvent casting techniques. The PVA composite films were also subjected to a range of analyses including IR, TGA, DTA, DTG, SEM, TEM, dielectric measurements and EMI shielding effectiveness (EMI SE), to describe their characteristics. The results of various studies indicate that the PVA/PANI/MWCNT/Fe3O4 (1%, 3%, 5%) composites possess enhanced thermal and dielectric characteristics, for instance the PVA/PANI/MWCNT/5% Fe3O4 blend nanocomposites possess 10% initial decomposition at 220°C and dielectric constant of 3.2 × 107 at 1 MHz. The total EMI SE value for the synthetic PVA/PANI/MWCNT/Fe3O4 was found at 9.2 and 10 GHz is 48 and 54 dB, respectively, exhibiting synergistic properties of the composites toward EMI shielding. The microwave absorption spectra indicate two absorption peaks in the region around 8 to 12 GHz, with the absorption reflection loss (RL) value of −20 dB at 10 GHz for the PVA/PANI/MWCNT/5% Fe3O4 nanocomposites.

The electromagnetic wave absorption composite of flower-like structure NiCo2O4 and Fe3O4 derived from low-temperature preparation method

The NiCo2O4@Fe3O4 composites with excellent electromagnetic wave absorption performance was prepared by the low-temperature (50 °C) co-precipitation method, avoiding the traditional high-temperature hydrothermal synthesis method. The specific surface area of the composite material was increased due to the combination of NiCo2O4 with 3D hierarchical flower-like structure and Fe3O4 with spherical structure, which is conducive to the full reflection and scattering of electromagnetic waves. The combination of typical magnetic material and excellent dielectric material could adjust the impedance matching value of the material and thus the absorption loss performance of electromagnetic wave was improved. The ε value of the dielectric material was larger than those of magnetic materials and the maximum reflection loss value appeared at the high frequency (the thickness is small), while the μ value of magnetic materials was larger than those of dielectric materials and the maximum reflection loss value generally appeared at low frequency (the thickness is large).The results showed that the maximum RL value reached −53.35 dB at about 13 GHz with the thickness of 2.0 mm and the effective absorption bandwidth was 4.4 GHz when the weight ratio (NiCo2O4:Fe3O4) of composite samples was 6:1. The excellent EMW absorption property was mainly due to the combination of NiCo2O4 and Fe3O4, which could achieve impedance matching to loss EMW by dielectric loss and magnetic loss.

Structure and electrochemical properties of magnetite and polypyrrole nanocomposites formed by pyrrole oxidation with magnetite nanoparticles

Nanocomposite of magnetic Fe3O4 nanoparticles and polypyrrole was prepared under sonication by a new chemical polymerization method during which Fe3O4 nanoparticles acted both as a pyrrole oxidant and as a component in the composite material. Synthesis of this nanocomposite was carried out in aqueous solution acidified to pH 2, a prerequisite for the formation of these types of material and to facilitate pyrrole oxidation by Fe3O4 nanoparticles. In this way, two kind of materials were produced: Fe3O4/PPy nanocomposite in which magnetite nanoparticles were dispersed in PPy matrix and Fe3O4-aggregates@PPy nanocomposite that exhibits structure in which aggregates of magnetite nanoparticles are surrounded by a layer of polymeric phase. In the latter case, the polymerization process took place in the presence of a surfactant. These nanocomposites were characterized by electron microscopy techniques, IR spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermogravimetry. Particular attention was focused on the study of the electrochemical properties of the formed composites. The composite of Fe3O4 and PPy exhibits reversible electrochemical behaviour upon oxidation. The electrode process of the polymeric component oxidation in organic solvents such as acetonitrile and dichloromethane is very similar to the process in an aqueous solution.

Construction of core-shell Fe3O4@MoS2 activates peroxymonosulfate for the degradation of tetracycline: Structure-activity relationship, performance and mechanisms

Peroxymonosulfate (PMS) is an excellent oxidant that can produce multiple radicals. A novel core-shell composite Fe3O4 @MoS2-x (F@M-x) heterostructure was synthesized to degrade tetracycline (TC) by PMS activation. In F@M/PMS catalytic system, more Fe(III) is reduced into Fe(II) by doping MoS2 nanoflowers formed core-shell structure, resulting in the catalytic process being significantly enhanced. Due to the strong complexation tendency of TC towards Fe(II), the Fe(II)-TC complexes* accumulated between the core and shell, which significantly accelerates the PMS activation and TC abatement compared to free Fe(II). The EPR and quenching experimental results revealed that O2•− and 1O2 were detected as the main active species for TC degradation in the F@M/PMS system. Furthermore, the possible TC degradation pathways were proposed and the toxicity estimation of intermediates was evaluated by Toxicity QSAR prediction. These results will be useful for the improvement of PMS-based AOPs activation and expand the application of Fe(II)/PMS systems in the treatment of water containing new organic micro-pollutants.

Investigating the Effect of Fe2O3 on Wear Behaviour and Corrosion Resistance of Electroless Ni–P Coating with Different Fe2O3 Concentrations on AISI 4140 Steel

In this study, Ni–P–Fe2O3 composite was deposited on AISI 4140 steel using different concentrations of Fe2O3 ranging from 0.1 to 0.5 gr/lit in an electroless bath. The phase analysis and surface morphology of the samples were characterized using X-ray diffraction and FESEM. The corrosion behavior of the coated samples was investigated in a 3.5 wt. % NaCl solution through potentiodynamic polarization. The results of the potentiodynamic test show that adding Fe2O3 into an electroless bath facilitates the formation of the passive layer. The results show that the coating created at a thickness of (10-16µm) had the highest corrosion resistance compared to other coated and non-coated samples. Furthermore, the results of the friction coefficients of the samples produced by powder metallurgy have decreased because Fe2O3 particles led to a decrease in grain size in the heat treatment of specimens and prevented excessive heat generation during the wear test; thus, the friction coefficient decreased during the test.

Evaluation of persulfate enhanced electrocoagulation (EC/PS) for bio-treated landfill leachate: Organics transformation pathways and carbon flow quantitative analysis

The sulfate radical-based advanced oxidation processes (SR-AOPs) have shown promise in treating bio-treated landfill leachate (BLL). However, little is known about the dissolved organic matter (DOM) transformation and reaction mechanisms at the molecular level after treating BLL using SR-AOPs. This study investigates the DOM degradation and transformation pathways during both electrocoagulation (EC) and persulfate enhanced electrocoagulation (EC/PS) of real BLL samples. The results indicate that the removal efficiency of chemical oxygen demand (COD) and total organic carbon (TOC) were enhanced to 46.34% and 36.39%, respectively, once persulfate is coupled with EC. Additionally, the removal of fluorescent contaminants in BLL significantly enhanced after treatment with EC/PS to 91.57%, 80.99%, and 39.10% for biogenic humic-like components C1, C2, and C3, respectively. A decrease in the proportion of macromolecular and aromatic matters was observed after the EC/PS process. The degree of oxidation of DOM was reduced, and the compounds with unstable structure and high biodegradability became the main compounds in the EC/PS effluent. The analysis of sediments generated by EC and EC/PS showed a similar composition of FeOOH and Fe3O4, although there was additional Fe2(SO4)3 in the EC/PS sludge. The degraded organics in the solution and sediment phase were quantified by material flow analysis, indicating that the precipitation was the main contributor to DOM removal during the EC/PS process. These findings aid in understanding the role of PS in the EC/PS process during real landfill leachate treatment and reevaluate the advantages and limitations of PS as an oxidant.

G-C3N4/Fe3O4 composites synthesized via solid-state reaction and photocatalytic activity evaluation of methyl blue degradation under visible light irradiation

This study applied the solid-state reaction technique to synthesize g-C3N4, Fe3O4, and g-C3N4/Fe3O4composites in various ratios. XRD confirmed the formation of g-C3N4, Fe3O4, and a g-C3N4/Fe3O4heterostructure. SEM confirmed the rod-shaped structure of Fe2O3and the layered-like fabrication of g-C3N4. The Egof g-C3N4/Fe3O4was approximately 1.9 eV, making it a beneficial composite material for visible response in photocatalysis activity, which was confirmed by UV-Vis spectroscopy. Dielectrics were used to study ferrite nanoparticles and provide information on the mechanism of conductivity in the parts of the dielectric that responded to an applied alternating electric field. In polycrystalline ceramics, the resistive and capacitive grains, contributions, electrode specimen interfaces, and grain boundaries may all be distinguished using impedance analysis, a crucial tool for the study of complicated electrical performance. The g-C3N4/Fe3O4composite material showed high photocatalytic activity against methylene blue (MB) dye.

Utilization of agricultural waste to herbicide removal: Magnetic BEA zeolite adsorbents prepared by dry-gel conversion using rice husk ash–derived SiO2 for paraquat removal

This study presents a method that will allow for the sustainable utilization of rice husk ash-SiO2 (RHAS), an agricultural-waste–derived material, as a bulky solid SiO2 source in the zeolite beta (BEA)/Fe3O4 composite (magnetic RHAS-BEA) synthesis via a dry-gel conversion method for the removal of paraquat, a typical herbicide, from aqueous solutions. Ultrasonic waves were used to facilitate the formation of uniform Fe3O4-contained dry precursor gel before converting to the magnetic BEA zeolite composite for the first time. Magnetic RHAS-BEA was then characterized and compared with a non-magnetic sample (RHAS-BEA) using X-ray diffraction and field-emission scanning electron microscopy. In terms of adsorption, we found that paraquat had a high adsorption rate on the samples and conformed to a pseudo-second-order kinetic model. The adsorption behavior of paraquat on the synthesized RHAS-BEA and magnetic RHAS-BEA obeyed the Langmuir adsorption isotherm model. The synthesized adsorbents were reusable for at least four cycles, via thermal regeneration at 450 °C. The inclusion of Fe3O4 particles in magnetic RHAS-BEA disrupted neither the crystallization of the BEA zeolite nor the adsorption of paraquat and enabled easy collection via an external magnet.

Plant-Mediated Synthesis of Ni-Doped CuO and Fe2O3 Nanocomposite for Photodegradation of Methylene Blue Dye

Cu1–xNixO/Fe2O3 (with x = 0.01, 0.02, 0.03, 0.04 wt%) were synthesized by plant extraction technique. The absorbance and degradation performance of Ni-doped CuO and Fe2O3 nanocomposite against methylene blue (MB) was analyzed, and the 2% Ni-doped CuO yielded an optimum result, and the optical bandgap of CuO, 2NCO, Fe2O3, and (60%) 2NCO/40% Fe2O3 was found to be 1.88, 1.73, 2.1, and 1.80 eV, respectively. Hence, the 2% Ni-doped CuO (2NCO) was further used for the establishment of a composite with Fe2O3. The lowest composition of the oxide composite was (1−x) 2NCO/(x) Fe2O3 (x = 0.1, 0.2, 0.3, 0.4, and 0.5). The degradation performance of those oxide composites was determined against (MB) with the nominal composition of sample (60%) 2NCO/40% Fe2O3 resulted in an optimum degradation of MB with a percentage of 94% at 120 min. The recyclability takes a look at was performed for five cycles at the start of 94%; after five cycles, the sample remained stable at 120 min. Therefore, 2NCO/40% Fe2O3 composite is going to be the selection material for waste product treatment.

In-situ magnetite deposited wood composites with extensive electromagnetic interference shielding performance

Wood is an insulator material, using its porous structure to endow it with efficient microwave absorption and broaden its application range is still a major challenge. Here, wood-based Fe3O4 composites with excellent microwave absorption properties and high mechanical strength were prepared by alkaline sulfite method, in-situ co-precipitation method and compression densification method. The results showed that the magnetic Fe3O4 was densely deposited in the wood cells, and the prepared wood-based microwave absorption composites had both high electrical conductivity, magnetic loss, excellent impedance matching performance and attenuation performance, as well as effective microwave absorption properties. In the frequency range of 2–18 GHz, the minimum reflection loss value was −25.32 dB. At the same time, it had high mechanical properties. Compared with the untreated wood, its modulus of elasticity (MOE) in bending increased by 98.77%, and modulus of rapture (MOR) in bending improved by 67.9%. The developed wood-based microwave absorption composite is expected to be used in electromagnetic shielding fields such as anti-radiation and anti-interference.

Porous carbon derived from cherry blossom leaves treatment with Fe3O4 enhanced the electrochemical performance of a lithium storage anode

Metal oxides have been proposed as promising anode materials for next-generation batteries, but the large volume changes and poor electron and ion conductivity limit their electrochemical performance. To mitigate the negative effects of volume expansion on battery performance, a flower-like Fe3O4 structure coated with carbon is studied via one step wet chemical method. The Fe3O4 particles are uniformly distributed in highly porous carbon derived from cherry blossom leaves, resulting in a larger specific area and higher conductivity for the Fe3O4@C anode. In this hybrid Fe3O4@C nanocomposite, the ultrafine carbon coating effectively reduces volume expansion while providing excellent electrochemical performance. The flower-like Fe3O4@C electrodes demonstrate a specific capacity of approximately 1110 mAh g–1 at a current density of 1.0 A g–1. Moreover, the composite material Fe3O4@C exhibits a specific capacity of 848.1 mAh g–1 at a high current density of 2.0 A g–1 over 1000 cycles. These results indicate that the hybrid composition Fe3O4@C possesses excellent electrochemical properties, and suggest that this strategy could be applied to other hybrid materials for energy harvesting and storage.

Au-Ag-Se-Te-S Mineralization in the Maletoyvayam High-Sulfidation Epithermal Deposit, Kamchatka Peninsula

The Maletoyvayam high-sulfidation (HS) epithermal Au-Ag deposit is one of the numerous hydrothermal deposits of the Kamchatka volcanogenic belt, consisting of two main associations: Au-rich (Ag-free) and Ag-bearing. The first one derived from acidic solutions, whereas the second assemblage crystallized from moderately dilute solutions, with both occurring at high oxygen fugacity. The Au-rich association contains the most atypical gold chalcogenides of the Au-Se-Te-S system, which are characterized by Se-S and Te-Se substitutions, e.g., a complete series from maletoyvayamite to tolstykhite Au3(Se,S)4Te6; a series of auroselenide Au(Se1.00–0.64S0.36–0.00); a combined series of gachingite Au(Te,Se) and unnamed Au(Se,Te): Au(Te0.80–0.40Se0.20–0.60). Meanwhile, in the second Ag-bearing assemblage, sulfides of the Au-Ag type prevails, e.g., petrovskaite AuAgS, miargyrite (Ag,Au)(Sb,As)S2, uytenbogaardtite Ag3AuS2, fischesserite Ag3AuSe2 with Au-Ag substitution, and tolstykhite. The Se/S ratio, of the second association, decreases while increasing the Ag concentration in the ore-forming system, including Au-Ag substitutions. The Au content in miargyrite (Au,Ag)SbS3 reaches up to 0.48 apfu, suggesting the existence of a new mineral phase of composition AgAuSb2S6. Au oxide complexes, in both associations, are represented by either a mixture of redeposited gold and Fe-Sb oxide or a homogeneous (Au,Sb,Fe)2O3 composition. These oxides are formed by replacement of calaverite. The ore mineralization of this HS deposit is considered unique due to the special conditions of the ore-forming environment, such as acidic solutions, high oxygen fugacity, and log fSe2 above −5.7; all contributed to the formation of AuSe phases.

Construction of polyacrylamide/chitosan quaternary ammonium salt/ferric oxide-tannic acid-polyaniline hydrogels with high detection sensitivity and electromagnetic dual function

In recent years, hydrogels have attracted extensive attention due to their unique properties. More and more studies have added new functions to hydrogels through modification, but the modified hydrogels only show unique properties in a specific aspect, which limits the application of hydrogels. Therefore, how to endow hydrogels with two or more functions at the same time has become a research hotspot. In this study, polyacrylamide and chitosan quaternary ammonium salt were used as the matrix of the hydrogel. The surface of magnetic ferric oxide nanoparticles (Fe3O4 NPs) was modified by tannic acid (TA). TA and Fe3O4 NPs were connected by coordination bonds to improve the surface properties of Fe3O4 NPs. Then aniline molecules were coated on the surface of Fe3O4-TA NPs by the electrostatic attraction through in-situ chemical polymerization under the action of sulfuric acid doping to obtain composite Fe3O4 NPs with electromagnetic dual functions. The electromagnetic bifunctional hydrogel was prepared by introducing the composite Fe3O4 NPs into the hydrogel through physical doping. The results showed that the hydrogel had excellent mechanical properties (the tensile strength was 113.3 kPa, the elongation was 1070%). Due to the existence of polyaniline, the hydrogel showed outstanding electrical properties (the conductivity was up to 24.3 mS/cm and the gauge factor was up to 9.43). In addition, Fe3O4 NPs gave the hydrogel good magnetism, and the hydrogel underwent a certain deformation in the switching magnetic field, which further expanded the application field of the hydrogel.

Removal of cadmium and lead ions from aqueous solutions by novel dolomite-quartz@Fe3O4 nanocomposite fabricated as nanoadsorbent

The elimination of heavy metal ion contaminants from residual waters is critical to protect humans and the environment. The natural clay (dolomite and quartz) based composite Fe3O4 nanoparticles (DQ@Fe3O4) has been largely explored for this purpose. Experimental variables such as temperature, pH, heavy metal concentration, DQ@Fe3O4 dose, and contact time were optimized in details. The DQ@Fe3O4 nanocomposite was found to achieve maximum removals of 95.02% for Pb2+ and 86.89% for Cd2+, at optimal conditions: pH = 8.5, adsorbent dose = 2.8 g L−1, the temperature = 25 °C, and contact time = 140 min, for 150 mg L−1 heavy metal ion initial concentration. The Co-precipitation of dolomite-quartz by Fe3O4 nanoparticles was evidenced by SEM-EDS, TEM, AFM, FTIR, XRD, and TGA analyses. Further, the comparison to the theoretical predictions, of the adsorption kinetics, and at the equilibrium, of the composite, revealed that they fit, respectively to, the pseudo-second-order kinetic, and Langmuir isotherm. These both models were found to better describe the metal binding onto the DQ@Fe3O4 surface. This suggested a homogenous monolayer sorption dominated by surface complexation. Additionally, thermodynamic data have shown that the adsorption of heavy metal ions is considered a spontaneous and exothermic process. Moreover, Monte Carlo (MC) simulations were performed in order to elucidate the interactions occurring between the heavy metal ions and the DQ@Fe3O4 nanocomposite surface. A good correlation was found between the simulated and the experimental data. Moreover, based on the negative values of the adsorption energy (Eads), the adsorption process was confirmed to be spontaneous. In summary, the as-prepared DQ@Fe3O4 can be considered a low-cost-effective heavy metals adsorbent, and it has a great potential application for wastewater treatment.