Sludge dewaterability improvement with microbial fuel cell powered electro-Fenton system (MFCⓅEFs): Performance and mechanisms

Throughout the entire process of sludge treatment and disposal, it is crucial to explore stable and efficient techniques to improve sludge dewaterability, which can facilitate subsequent resource utilization and space and cost savings. Traditional Fenton oxidation has been widely researched to enhance the performance of sludge dewaterability, which was limited by the additional energy input and the instabilities of Fe2+ and H2O2. To reduce the consumption of energy and chemicals and further break the rate-limiting step of the iron cycle, a novel and feasible method that constructed microbial fuel cell powered electro-Fenton systems (MFCⓅEFs) with ferrite and biochar electrode (MgFe2O4@BC/CF) was successfully demonstrated. The MFCⓅEFs with MgFe2O4@BC/CF electrode achieved specific resistance filtration and sludge cake water content of 2.52 × 1012 m/kg and 66.54 %. Cellular structure and extracellular polymeric substances (EPS) were disrupted, releasing partially bound water and destroying hydrophilic structures to facilitate sludge flocs aggregation, which was attributed to the oxidation of hydroxyl radicals. The consistent electron supply supplied by MFCⓅEFs and catalytically active sites on the surface of the multifunctional functional group electrode was responsible for producing more hydroxyl radicals and possessing a better oxidizing ability. The study provided an innovative process for sludge dewaterability improvement with high efficiency and low energy consumption, which presented new insights into the green treatment of sludge.

Enhancing hydrogen generation from sodium borohydride hydrolysis and the role of a Co/CuFe2O4 nanocatalyst in a continuous flow system

In this study, a series of cobalt-based spinel ferrites catalysts, including nickel, cobalt, zinc, and copper ferrites, were synthesized using the sol-gel auto-combustion method followed by a chemical reduction process. These catalysts were employed for accelerating hydrogen generation via the sodium borohydride hydrolysis process. A continuous stirred tank reactor was used to perform catalytic reactor tests. All samples were subjected to analysis using XRD, FESEM, EDX, FTIR, and nitrogen adsorption-desorption techniques. The results revealed that the cobalt-based copper ferrite sample, Co/Cu-Ferrite, exhibited superior particle distribution, and porosity characteristics, as it achieved a high hydrogen generation rate of 2937 mL/min.gcat. In addition, the higher electrical donating property of Cu-Ferrite which leads to the increase in the electron density of the cobalt active sites can account for its superior performance towards hydrolysis of NaBH4. Using the Arrhenius equation and the zero-order reaction calculation, activation energy for the sodium borohydride hydrolysis reaction on the Co/Cu-Ferrite catalyst was determined to be 18.12 kJ/mol. This low activation energy compared to other cobalt-based spinel ferrite catalysts confirms the catalyst's superior performance as well. Additionally, the outcomes from the recycling experiments revealed a gradual decline in the catalyst's performance after each cycle during 4 repetitive cycles. The aforementioned properties render the Co/Cu-Ferrite catalyst an efficient catalyst for hydrogen generation through NaBH4 hydrolysis.

Bentonite as eco-friendly natural mineral support for Pd/CoFe2O4 catalyst applied in toluene diamine synthesis

Toluene diamine (TDA) is a major raw material in the polyurethane industry and thus, its production is highly important. TDA is obtained through the catalytic hydrogenation of 2,4-dinitrotoluene (2,4-DNT). In this study a special hydrogenation catalyst has been developed by decomposition cobalt ferrite nanoparticles onto a natural clay-oxide nanocomposite (bentonite) surface using a microwave-assisted solvothermal method. The catalyst particles were examined by TEM and X-ray diffraction. The palladium immobilized on the bentonite crystal surface was identified using an XRD and HRTEM device. The obtained catalyst possesses the advantageous property of being easily separable due to its magnetizability on a natural mineral support largely available and obtained through low carbon- and energy footprint methods. The catalyst demonstrated outstanding performance with a 2,4-DNT conversion rate exceeding 99% along with high yields and selectivity towards 2,4-TDA and all of this achieved within a short reaction time. Furthermore, the developed catalyst exhibited excellent stability, attributed to the strong interaction between the catalytically active metal and its support. Even after four cycles of reuse, the catalytic activity remained unaffected and the Pd content of the catalyst did not change, which indicates that the palladium component remained firmly attached to the magnetic support's surface.

Mercury remediation from wastewater through its spontaneous adsorption on non-functionalized inverse spinel magnetic ferrite nanoparticles

In this study, inverse spinel cubic ferrites MFe2O4 (M = Fe2+, and Co2+) have been fabricated for the high-capacity adsorptive removal of Hg(II) ions. The PXRD analysis confirmed ferrites with the presence of residual NaCl. The surface area of Fe3O4 (Fe-F) and CoFe2O4 (Co-F) material was 69.1 and 45.2 m2 g-1, respectively. The Co-F and Fe-F showed the maximum Hg(II) adsorption capacity of 459 and 436 mg g-1 at pH 6. The kinetic and isotherms models suggested a spontaneous adsorption process involving chemical forces over the ferrite adsorbents. The Hg(II) adsorption process, probed by X-ray photoelectron spectroscopy (XPS), confirmed the interaction of Hg(II) ions with the surface hydroxyl groups via a complexation mechanism instead of proton exchange at pH 6 with the involvement of chloride ions. Thus, this study demonstrates a viable and cost-effective solution for the efficient remediation of Hg ions from wastewater using non-functionalized ferrite adsorbents. This study also systematically investigates the kinetics and isotherm mechanism of Hg(II) adsorption onto ferrites and reports one of the highest Hg(II) adsorption capacities among other ferrite-based adsorbents.

Impact of high energy photons on physical, structural and magnetic properties of Mn0.65Zn0.35Fe2-xNdxO4 nanoparticles

Ultrafine powders of Nd+3 doped Mn-Zn ferrite powders with composition Mn0.65Zn0.35Fe2-xNdxO4 (x = 0.04, 0.06, 0.08) were prepared using the combustion method of preparation. Monophasic nanoparticle formation was confirmed by X-ray diffraction. The particle size was determined using a Transmission electron microscope (TEM). The nanopowders were investigated for their physical, structural, and magnetic properties and then radiated with gamma photons obtained from Co60 source with a dose of 500Gy, 750Gy and 1000Gy. The characterization of radiated powders showed preservation of spinel structure with breaking down of crystallites into finer crystals with increment in amorphous content. Structural and physical parameters were drastically altered due to high-energy photon exposure. The breaking down of larger particles was observed as a result of photon energy impact on the samples. The Saturation magnetization of ferrite nanoparticles was observed to increase with increasing gamma radiation dose. Mössbaure spectra showed the dominance of Fe+3 in the high spin state.

Enhanced therapeutic action of Trastuzumab loaded ZnxMn1-xFe2O4 nanoparticles using a pre-treatment step for hyperthermia treatment of HER2+ breast cancer

In this study, Ferrites (Fe3O4, MnFe2O4, ZnFe2O4) and different stoichiometric ratios of ZnxMn1-xFe2O4 (x = 0.2, 0.4, 0.6, and 0.8) nanoparticles (<15 nm) were synthesized by microwave-assisted method and optimised for hyperthermia studies. The selection of the optimised variant of ferrite i.e. Zn0.4Mn0.6Fe2O4 was found to be the best variant based on VSM (38.14 emu g-1) hyperthermia-based temperature rise (maximum ΔT of 38 °C), SAR and ILP values. Trastuzumab, which is known to bind with HER2 receptors of breast cancer was chemically tethered onto Zn0.4Mn0.6Fe2O4 nanoparticles through EDC/NHS coupling with a loading efficiency of 80%. The attached Trastuzumab aided during the pre-treatment step by aiding in the internalisation of Zn0.4Mn0.6Fe2O4 nanoparticles, with cellular uptake of 11% in SK-BR-3 (cancerous HER2+) cells compared to ∼5% for MDA-MB-231 (cancerous HER2-) and RPE-1 (non-cancerous) cells. In the presence of a hyperthermia trigger for 15 mins, ZnxMn1-xFe2O4 -Trastuzumab formulation had a maximum therapeutic effect by reducing the SK-BR-3 cell viability to 14% without adversely affecting the RPE-1 cells. The mechanism of ZnxMn1-xFe2O4-Trastuzumab combination was examined using an internalisation study, MTT-based viability, proliferation study, and ROS generation assay. By utilizing both Trastuzumab and hyperthermia, we achieve their synergistic anticancer properties while minimizing the drug requirement and reducing any effect on non-cancerous cells.

[Surface modification of multifunctional ferrite magnetic nanoparticles and progress in biomedicine]

Magnetic ferrite nanoparticles (MFNPs) have great application potential in biomedical fields such as magnetic resonance imaging, targeted drugs, magnetothermal therapy and gene delivery. MFNPs can migrate under the action of a magnetic field and target specific cells or tissues. However, to apply MFNPs to organisms, further modifications on the surface of MFNPs are required. In this paper, the common modification methods of MFNPs are reviewed, their applications in medical fields such as bioimaging, medical detection, and biotherapy are summarized, and the future application directions of MFNPs are further prospected.

"Magnetic Ni-Zn ferrite anchored on g-C3N4 as nano-photocatalyst for efficient photo-degradation of doxycycline from water"

In the present work, mixed-spinel ferrite anchored onto graphitic carbon nitride (GCN) was synthesized for mineralization of antibiotic pollutant from waste water. A Z-scheme g-C₃N₄/Ni_0.5Zn_0.5Fe₂O₄ nano heterojunction was fabricated by three step procedure: pyrolysis, solution combustion and mechanical grinding followed by annealing. The prepared photocatlyst was tested for degradation of Doxycycline (DC) drug under the natural sun light. Results revealed that the prepared heterojunction has maximum degradation efficiency of 97.10% pollutant in 60 min experiment. The Z-scheme heterojunction between g-C₃N₄ and Ni-Zn ferrite improves the photoinduced charges separation and protection of redox capability and therby increases the photo degradation efficiency. The scavenging experiments suggested that O₂^-● and h⁺ as main active species responsible for degradation of the antibiotic. In addition, the dopant variation can drive the shists in band gap and energy band positiong too which makes then excellent candidates for synthesizing tunable heterostructures with organic semiconductors. The work focusses on designing and developing of saimpler but efficient magnetic heterojunctions with superior redox capability for solar powered waste water treatment.

Synthesis of a new magnetic Sulfacetamide-Ethylacetoacetate hydrazone-chitosan Schiff-base for Cr(VI) removal

In this study, a novel magnetic organic-inorganic composite was fabricated. Where, Chitosan, sulfacetamide and ethylacetoacetae were used to prepare a new Sulfacetamide-Ethylacetoacetate hydrazone-chitosan Schiff-base (SEH-CSB) with a variety of active sites that capable of forming coordinate covalent bonds with Cr(VI). This was followed by modification of the formed SHE-CSB with NiFe₂O₄ to obtain the magnetic Chitosan-Schiff-base (NiFe₂O₄@SEH-CSB). NiFe₂O₄@SEH-CSB was characterized using FTIR, zeta potential, SEM, VSM and XPS. Results clarified that SHE played a crucial role in the removal of Cr(VI). The removal of Cr(VI) on NiFe₂O₄@SEH-CSB was found to be more fitted to pseudo-2nd order kinetics model and Freundlich isotherm. Besides, the maximum adsorption capacity of NiFe₂O₄@SEH-CSB for Cr(VI) was found to be 373.61 mg/g. The plausible mechanism for the removal of Cr(VI) on NiFe₂O₄@SEH-CSB composite suggested coulombic interaction, outer-sphere complexation, ion-exchange, surface complexation and coordinate-covalent bond pathways. The magnetic property enabled easy recycling of NiFe₂O₄@SEH-CSB composite.

Highly efficient visible light photocatalysis of Nix Zn1-x Fe2O4 (x= 0, 0.3, 0.7) nanoparticles: Diclofenac degradation mechanism and eco-toxicity

Pharmaceuticals and personal care products occupy a predominant position with respect to both utility and release into the ecosystem, thereby contributing to environmental pollution at alarming rates. Of the several methods identified to minimize the concentration of PPCPs, nanomaterial based photocatalysis seems to be a potential alternative for it being highly economical and eco-friendly. In this study, we synthesized Nickel zinc ferrite (Ni-ZF) [Ni_x Zn_1-x Fe₂O₄ (x = 0, 0.3, 0.7)] nanoparticles with an average diameter of ∼400 nm by a co-precipitation method towards diclofenac degradation. The composite showed greater degrees of crystallinity devoid of any impurities. Nearly complete DCF degradation (∼99%) was achieved after 50 min reaction time with the nanoparticles at pH 7 for an initial DCF concentration of 50 mg/L. The degradation process followed a pseudo first-order rate law with the rate constant of 0.1657 min^{- 1}. Microbial toxicity and phytotoxicity studies demonstrated negligible toxicity imposed by the contaminated water treated with the prepared composite, suggesting it as a promising photocatalyst benefitting in all aspects.

Toxic cadmium selective sequestration from food samples using melamine anchored magnetic cellulose by surface imprinting route

Cadmium is very toxic for living organisms hence selective and efficient control capturing of it is necessary. To reach this goal a novel imprinted polymer was developed using melamine anchored MnFe₂O₄ - cellulose. Magnetic cellulose was synthesized through an ultrasound-assisted precipitation route. Chloropropyltriethoxysilane was used to attach melamine to the magnetic cellulose surface. Response surface methodology employed to optimize effective parameters on cadmium adsorption. Time of 13 min, the dosage of 18 mg and pH of 8 was selected as optimum conditions. The relative standard deviation, detection limits and adsorption capacity were 2,5%, 0.50 µgL^-1 and 138 mg g^-1 respectively. The selectivity coefficient of Cd(II) relative to Cu(II), Co(II), Ni(II) and Pb(II) were 4, 5, 12 and 3, respectively. Regeneration of the sorbent was performed using HCl (0.5 mol L^-1) as eluent. The method was used for cadmium preconcentration in fish, lettuce and liver with satisfactory results.

Metal recovery and heavy metal migration characteristics of ferritic stainless steel pickling sludge reduced by municipal sludge

A new method for recovering metals from ferritic stainless steel pickling sludge using municipal sludge as a reducing agent is proposed. The effects of temperature, municipal sludge blending ratio, and reaction atmosphere on the recovery characteristics were studied. The migration characteristics of heavy metals (HMs) at different temperatures were also investigated. The results showed that municipal sludge can be used as a reducing agent for metal recovery from pickling sludge. Under optimized conditions (temperature of 650 °C and blending ratio of 5%), the recovery fractions of Fe, Cr, and Ni were 70.1, 53.7, and 60.3%, respectively. The CO₂ atmosphere was beneficial for increasing the recovery fraction of the pickling sludge. The migration fractions of Cr, Mn, and Ni were approximately 10%. The migration fractions of Zn, Cu, and Pb, which are semi-volatile HMs, varied significantly with temperature. The migration fractions of Cd and As, which are volatile HMs, could exceed 70%.

Interconnected magnetic carbon@NixCo1-xFe2O4 nanospheres with core-shell structure: An efficient and thin electromagnetic wave absorber

The applications of cobalt ferrite and nickel ferrite composite materials on electromagnetic (EM) wave absorption are the research hotspot currently. However, the systematical comparison study between these two ferrites composites have rarely been carried out. Thus, the EM wave absorption performance of interconnected carbon@Ni_xCo_1-xFe₂O₄ composites with core-shell structures were investigated comprehensively in this work. A series of magnetic nanospheres including NiFe₂O₄, cobalt-doped nickel ferrite, nickel-cobalt ferrite, nickel-doped cobalt ferrite and CoFe₂O₄ were synthesized firstly, and then uniformly encapsulation by carbon rendered the corresponding C@Ni_xCo_1-xFe₂O₄ composites nanospheres. Synthesis reactions involved for C@Ni_xCo_1-xFe₂O₄ formation were investigated in detail, and afterwards their magnetic behavior, EM wave absorption performance and absorbing mechanism were thoroughly explored and analyzed. Results show that when nickel is dominant element and cobalt is doping element (Ni_0.75Co_0.25Fe₂O₄), the composite nanosphere exhibits optimum EM wave absorption performance. When the sample thickness is just 1.9 mm, its RL_min value can reach -51 dB, and the corresponding EAB width is 3.3 GHz. The synthesized C@Ni_0.75Co_0.25Fe₂O₄ can be qualified as an efficient and thin electromagnetic wave absorber, which is mainly attributed to its special structure, fair electromagnetic matching and impedance matching.

Green preparation of carbon quantum dots with wolfberry as on-off-on nanosensors for the detection of Fe3+ and l-ascorbic acid

A green and facile hydrothermal synthesis approach is proposed for the preparation of nitrogen-doped carbon quantum dots (N-CQDs) with wolfberry. These N-CQDs were developed as a highly sensitive fluorescent 'on-off-on' switch sensor for the sensing of Fe3+ and l-ascorbic acid (AA). The N-CQDs displayed superior fluorescence characteristics of CQDs with a quantum yield up to 22%. The N-CQDs were demonstrated to selectively react with Fe3+, leading to fluorescence quenching effect, which was successfully used for the detection of Fe3+ with a limit of detection at 3 μmoL•L-1. The addition of AA is supposed to repair the surface defects, and result in the fluorescence recovery. Based on this effect, the strategy of 'on-off-on' detection of AA was established with a limit of detection at 1.8 μmoL•L-1. Furthermore, the practical application of the detection of Fe3+ lake water and AA in medical tablet was demonstrated, promising an effective and efficient 'on-off-on' nanosensor with low-cost, green synthesis for Fe3+ and AA detection.

Multimodal polymer encapsulated CdSe/Fe3O4 nanoplatform with improved biocompatibility for two-photon and temperature stimulated bioapplications

Multimodal polymer encapsulated CdSe/Fe₃O₄ nanoplatforms with dual optical and magnetic properties have been fabricated. We demonstrate that CdSe/Fe₃O₄ nanocapsules (NCs) upon excitation with UV radiation or NIR fs-laser excitation exhibit intense one- or two-photon emission at 535 nm, whereas the combination of an alternating magnetic field and 808 nm IR laser excitation results in heat generation. Since anticancer therapies require relatively high doses of Fe₃O₄ nanoparticles (NPs) to induce biologically relevant temperature jumps, the therapeutic effects of 0.1 and 1 mg/mL Fe₃O₄ NCs and CdSe/Fe₃O₄ NCs were investigated using breast cancer cell lines, ER-positive MCF-7, and triple-negative MDA-MB-231 cells. Improved biocompatibility of CdSe/Fe₃O₄ NCs compared to Fe₃O₄ NCs was revealed at higher NCs concentration suggesting safe potential medical applications of CdSe/Fe₃O₄ NCs. In contrast, 1 mg/mL Fe₃O₄ NCs were found to be more cytotoxic to MDA-MB-231 than MCF-7 cells through iron-induced oxidative stress, lipid peroxidation, and concomitant ferroptotic cell death. We believe that Fe₃O₄ NCs-mediated cellular response may be heterogeneous that reflects, at least in part, cancer cell genotype, molecular phenotype, and pathological classification.

Low-cost nanoparticulate oxidation catalysts for the removal of azo and anthraquinic dyes

PURPOSE

This study aimed to test the activity of Mn ferrite, hematin-Mn ferrite and colloidal maghemite in decomposition of Orange II (O-II) and Alizarin Red S (ARS) in model aqueous solutions.

METHODS

Color removal was explored at room temperature using magnetic stirring with and without a magnetic bar, taking advantage of the solids' magnetism. Decomposition of H₂O₂ was also studied separately and as radicals provider in dye decomposition. Catalyst/dye solution was fixed at 10 mg/4 mL. pH and dye concentration were variable. Absorbance was measured during 120 min by UV-Vis. Reuse of catalysts was also performed.

RESULTS

Azo dyes such as O-II are more resistant to oxidative removal using hydrogen peroxide than anthraquinone-like ARS. CITMD5 reduced ARS absorbance up to 71.9% when dye was less than 250 mg/L. HEM-Mn-MAG completely decolorized a 62.5 mg/L O-II solution at pH 11 while CITMD5 reached half of that conversion under the same conditions. The highest color removal in O-II/ARS mixtures was obtained with HEM-Mn-MAG, 40% absorbance reduction in 2 h. Mn-MAG is not active to remove O-II in presence of hydrogen peroxide in the 3-9 pH range at rt.

CONCLUSIONS

The high activity of Mn-MAG in hydrogen peroxide decomposition may be assigned to the combination of Mn⁺²/Mn⁺³ and Fe⁺²/Fe⁺³, because the MnO_x is active in the decomposition of hydrogen peroxide. Mn-MAG can be reused, preserving high activity in this reaction. Mn-based magnetic nanoparticles should be considered as inexpensive materials to treat textile wastewaters.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-021-00640-x.

Magnesium-zinc ferrites as magnetic adsorbents for Cr(VI) and Ni(II) ions removal: Cation distribution and antistructure modeling

The magnesium-zinc ferrites Mg_1-xZn_xFe₂O₄ (x = 0…1) were studied as magnetic sorbents for environmental applications. Low-temperature Mössbauer spectroscopy was used to determine the distribution of magnesium and ferric ions in the spinel crystal lattice. The influence of Zn content on magnetic parameters was investigated on the basis of VSM data. As the molar ratio of zinc to magnesium increases from 0 to 1, the pH_PZC value decreases from 10.5 to 8.9. Langmuir and Freundlich models were used to check whether single-layer or multi-layer adsorption occurs. The adsorption of Cr(VI) and Ni(II) ions is well fitted by the Langmuir equation. To check the physical or chemical nature of the sorption process, the Dubinin-Radushkevich equation was used. It was found that the processes of adsorption of Cr(VI) and Ni(II) ions are of a chemical nature. The best Cr(VI) ion adsorption capacity was found for the Mg_0·2Zn_0·8Fe₂O₄ sample (q_e = 30.49 mg/g). The percentage of heavy metal removal by the mixed ferrite samples increases with increasing zinc content. The most effective sorbent for Ni(II) removal is the Mg_0·4Zn_0·6Fe₂O₄ sample (93.2%). Modeling the antistructure provides deeper insight into the mechanism of heavy metal adsorption. The obtained magnesium-zinc ferrites are promising magnetic adsorbents for removing chromate and nickel ions from the environment.

β-Cyclodextrin-folate functionalized poly(lactic-co-glycolide)-superparamagnetic ytterbium ferrite hybrid nanocarrier for targeted delivery of camptothecin

Biocompatible polymer-coated magnetic nanoparticles are designed with an objective to sharp-shoot cancer by loading anticancer drugs on them and delivering to the target site. In this work, novel biocompatible polymers of poly(dl-lactic-co-glycolide), functionalized with β-cyclodextrin and β-cyclodextrin-folate conjugate are synthesized and characterized by spectroscopic techniques. Magnetic ytterbium ferrite nanoparticles are prepared, and the synthesized polymers are coated on them. The polymer-coated nanoparticles are intended to be employed as magnetic nanocarriers that transport the anticancer drug, camptothecin. The ferrite nanoparticles are superparamagnetic in nature. Camptothecin was loaded in the nanocarriers and the adsorption percentage was near or above 90%. Study of the in vitro release of camptothecin from the nanocarrier reveals its sustained nature, i.e. a cumulative release of about 50% at 72 h and a pH of 7.4. A pH-dependent enhanced release of 60% is observed, i.e. at a more acidic pH of 6.8. In vitro anti-cancer studies on breast cancer cell lines (MCF7) were carried out. The cell inhibition is enhanced in the case of camptothecin-loaded nanocarrier. The enhanced efficacy of the camptothecin, its sustained release, and the size of the nanocarrier in the range that is considered suitable for magnetic field-assisted drug delivery reveal the magnetic nanocarrier promising for transport of the drug.

Green Synthesis of CuFe2O4@Ag Nanocomposite Using the Chlorella vulgaris and Evaluation of its Effect on the Expression of norA Efflux Pump Gene Among Staphylococcus aureus Strains

Increasing drug resistance among Staphylococcus aureus is a global health threat and finding alternative antimicrobial agents against it has been considered. Multidrug resistance efflux pumps, including NorA, are involved with resistance to different drugs, especially fluoroquinolones, in S. aureus. Using metal nanoparticles against pathogenic bacteria is a promising approach; however, physio-chemical synthesis of nanoparticles has limitations. Biosynthesis of metal nanoparticles with antibacterial activity has gained interest, recently. In this study, biosynthesis of CuFe₂O₄@Ag nanocomposite using aqueous extract from microalgae Chlorella vulgaris was performed, and its antibacterial property and effect on expression of norA efflux pump gene were investigated. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive X-ray mapping analysis (EDX-map), differential reflectance spectroscopy (DRS), and dynamic light scattering (DLS) were used to characterize synthesized nanocomposite. Antibacterial activity of the prepared nanocomposite individually and combined with ciprofloxacin against S. aureus strains was evaluated using the disk assay method, and minimum inhibitory concentration (MIC) of each agent was determined using the broth dilution method. Anti-biofilm activity of this nanocomposite was checked. Finally, the effect of CuFe₂O₄@Ag nanocomposite alone and in combination with ciprofloxacin on the expression of norA was assessed by real-time PCR. The physical analysis revealed proper synthesis of spherical and well-dispersed CuFe₂O₄@Ag nanocomposite with an average diameter of 20 nm. Synthesized nanocomposite had synergistic antibacterial activity with ciprofloxacin. Moreover, expression of norA gene among clinical and standard strains treated with CuFe₂O₄@Ag nanocomposite combined with ciprofloxacin reduced by 59% and 65%, respectively. Thus, CuFe₂O₄@Ag nanocomposite synthesized in this study can be considered as a promising candidate to be used to inhibit staphylococcal efflux pump genes and increasing the antibiotic efficacy.

Electrospun PU nanofiber composites based on carbon nanotubes decorated with nickel-zinc ferrite particles as an adsorbent for removal of hydrogen sulfide from air

This study focuses on the synthesis of carbon nanotubes decorated with nickel-zinc ferrites and fabrication of polyurethane (PU) nanofiber containing CNT-ferrite composites as highly efficient adsorbents for removal of hydrogen sulfide. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, and powder X-ray diffraction (PXRD) are used to perform microstructural and morphological characterization of the electrospun nanofibrous composites. To show the efficiency of the composite as an adsorbent, a breakthrough test is carried out. It is shown that the PU-CNT-ferrite composites are fabricated almost uniformly with an average fiber diameter of 320 nm and exhibit significant H₂S breakthrough capacity (498 mgH₂S/g) compared to both the pristine PU and PU-CNT nanofibers. These electrospun nanofibers based on CNT-ferrite composites, already studied for H₂S adsorption with promising results, open up new and interesting perspective into the design and fabrication of highly efficient membrane for practical application in the processes of air purification.

Datasets on the measurement of mechanical properties of ferrite and austenite constitutive phases using nanoindentation and micro hardness techniques

The major objective of this work is to study the hardness data at the domain of ferrite and Austenite phases. Nanoindentation and microhardness study has been conducted on austenite and ferrite present in the microstructure of hot rolled and heat treated duplex stainless steel (2205 DSS). Furthermore, Optical microscopy and field emission scanning electron microscope (FE-SEM) were used to identify the microstructural distribution and phases present. Austenite reveals higher nanohardness data value than ferrite, as oppose to ferrite average elastic modulus which is higher than that of austenite. Also, higher value of microhardness data was observed for austenite in comparison with the ferrite at different load application.

Control sonochemical parameter to prepare pure Zn0.35Fe2.65O4 nanostructures and study their photocatalytic activity

Zn_0.35Fe_2.65O₄ nanostructure was prepared as a ferrite material by using a simple sonochemistry method. The effect of different parameters such as sonication time and power were studied. By increasing sonication power and time more Fe⁺³ ions reduced to Fe⁺². This happens because H and OH radicals produced under sonication could act as a reduction agent. Therefore by increasing power and sonication time more Fe⁺³ ions reduced. Pure Zn_0.35Fe_2.65O₄ nanostructure was formed when sonication time and power were 30 min and 40 W. Surface area for pure Zn_0.35Fe_2.65O₄ nanostructure was 64 m².g^-1. Afterward, Zn_0.35Fe_2.65O₄ nanostructures were applied to treat water containing different pollutants. As-prepared nanostructures degrade 60.8, 77.9, 55.2 and 44.0% of Acid Violet 7, Acid Blue 92, Acid Red 14, and Methyl Orange under visible light during 180 min irradiation. In addition, 94.5, 84.2, and 43.0% of AV7, PhR, and Ery were degraded under UV light during 120 min irradiation. The as-synthesized Zn_0.35Fe_2.65O₄ nanostructure was characterized through the SEM, EDX, TEM, CV, DRS, BET, VSM, and XRD.

Treatment of simulated electroplating wastewater containing Ni(II)-EDTA by Fenton oxidation combined with recycled ferrite process under ambient temperature

Developing low cost and efficient method for the treatment of electroplating wastewater containing heavy metals complexed with chelating agent has attracted increasing attention in industrial wastewater treatment. This study involved a system combining Fenton oxidation (FO) and recycled ferrite (RF) process for treating synthetic solution containing Ni(II)-EDTA at ambient temperature. In this system, the FO reaction can produce hydroxyl radicals with high redox potential to decomplex the metal-organic complexes and degrade the organics, thereby enhancing the removal efficiency of heavy metals. The RF process is to incorporate the non-iron metal into the spinel ferrites at room temperature, and stabilize the sludge. As a result, the toxicity characteristic leaching procedure can fulfill the relevant standards. Furthermore, the ferrous ions in Fenton reaction could be used as the source of irons in RF process. After treatment by the combined process, the effluent water fulfills the relevant standard in China. In comparison with conventional alkaline precipitation, the sludge sedimentation velocity of FO-RF is 2.16 times faster than that of conventional alkaline precipitation and the volume of sludge is reduced by half, which strongly demonstrated the advantages of the presented FO-RF system and indicated the huge potential for the treatment of EDTA-chelated nickel.

Influence of preparation method on structural, optical, magnetic, and adsorption properties of nano-NiFe2O4

Nickel ferrite (NiFe₂O₄) nanoparticles are prepared through different routes (microwave, co-precipitation, and pyrolysis) and tested for water purification applications through adsorption removal of an acid red dye B as a model organic pollutant. The characterizations of the prepared samples were done using XRD, FT-IR, SEM, TEM, BET, UV-Vis absorbance, Raman spectrum, and vibrating sample magnetometer (VSM). All samples showed an inverse spinel crystal structure. The obtained results pointed out to the effect of the synthetic route on the morphology, particle size, optical, and magnetic properties of the prepared ferrites. Magnetic measurements showed super-paramagnetic behavior for all samples. The magnetic saturation (M_s) of the sample prepared by pyrolysis, was found to possess the highest saturation value, 34.8 emu/g. Adsorption experiments were performed under the change in several parameters, such as pH, adsorbent dosage, and initial dye concentration. A dye removal percentage of 99% was reached under the optimum state. The isothermal adsorption of the acid red dye was investigated using several models, in which the experimental data could be best described by the Freundlich model. Several kinetic and equilibrium models were inspected by linear regression analysis and showed best fitting for the adsorption data through pseudo-second-order model. The calculated thermodynamic parameters indicated that the adsorption of acid red dye onto all the ferrite samples is a spontaneous and endothermic physical adsorption process.

Selective adsorption of uranyl and potentially toxic metal ions at the core-shell MFe2O4-TiO2 (M=Mn, Fe, Zn, Co, or Ni) nanoparticles

Potentially toxic metal ions (Xⁿ⁺: Rb⁺, Sr²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Zn²⁺, Cd²⁺) usually coexist with uranyl (UO₂⁺), which will have a great influence on the selective adsorption process. Here, the core-shell MFe₂O₄-TiO₂ (M = Mn, Fe, Zn, Co, or Ni) nanoparticles were synthesized and assessed as new selective adsorbents. The results reveal that TiO₂(101) preferentially grows along the MFe₂O₄(311)/(111) orientation. The M²⁺ ions as the mediators transfer the holes from MFe₂O₄ to TiO₂, at the conduction bands. On the TiO₂(101) surfaces and TiO₂(101)-TiO₂(101) gaps, the paired active electrons mainly complex with water molecules as hydroxyl radicals to capture Xⁿ⁺ ions, forming an ion layer to block UO₂²⁺ from being adsorbed. Simultaneously, it should be noted that an interesting adsorption pathway was UO₂²⁺ being horizontally and irreversibly adsorbed in the MFe₂O₄(311)/(111)-TiO₂(101) interface, and therein, the stable adsorption capacity was found to be 66.78 mg g^-1 in the MnFe₂O₄(311)/(111)-TiO₂(101) interface. Finally, a mechanism of hybrid orbitals between MnFe₂O₄-TiO₂ and UO₂⁺-Xⁿ⁺ was proposed.

Porous MnFe2O4@SiO2 magnetic glycopolymer: A multivalent nanostructure for efficient removal of bacteria from aqueous solution

The focuses of this research is to prepare an efficient magnetic glycopolymer for bacteria removal from aqueous solution. To perform this idea; porous MnFe₂O₄@SiO₂ was functionalized with glucose and or maltose as an anchors to adhere onto bacteria cell surface. Aminopropyltriethoxysilane was employed to link the saccharides on magnetic nanoparticle surface. The hybrid materials were characterized with XRD, VSM, FT-IR, FESEM, TEM, zeta potential measurement and elemental mapping. Microscopic image showed that MnFe₂O₄ is in cluster form composed from tiny nanoparticles. After saccharide functionalization hybrid composite generate hyper-crosslinked porous structure as a result of polysilicate formation due to hydrolysis of silica source. Escherichia coli and bacillus subtilis were selected as sample pathogens to evaluate the bacteria capturing ability of the magnetic glycopolymer. At the optimum conditions (pH = 6, time of 20 min, dosage of 15 mg) removal efficiency was more than 99% using both saccharide.

Stabilizing cadmium into aluminate and ferrite structures: Effectiveness and leaching behavior

The inappropriate disposal of sludge, particularly for those enriched in heavy metals, is highly hazardous to the environment. Thermally converting sludge into useful products is a highly promising technique as heavy metals are immobilized and organic substances are mineralized. This work investigated the feasibility of stabilizing simulated cadmium-laden sludge by sintering with Al-and Fe-rich precursors. To simulate the process, cadmium oxide was alternatively mixed and sintered with γ-Al₂O₃ and α-Fe₂O₃. Cadmium was crystallographically incorporated into aluminate (CdAl₄O₇) monoclinic structure and ferrite (CdFe₂O₄) spinel, dependent on the type of precursor used. The CdFe₂O₄ formation was initialed at about 150-300 °C lower than that of CdAl₄O₇. With Rietveld refinement analysis of the collated XRD data, the weight percentages of crystalline phases in the fired samples were quantified. To evaluate the cadmium incorporation efficiency, a transformation ratio (TR) index was devised. The TR values revealed that, to effectively incorporate cadmium, 950 °C was favored by γ-Al₂O₃ and 850 °C was for α-Fe₂O₃ within a 3-h sintering treatment. Constant pH leaching test (CPLT) was used to assess the metal stabilization effects, revealing a remarkable reduction of cadmium by transformation into CdAl₄O₇ and CdFe₂O₄. Both CdAl₄O₇ and CdFe₂O₄ were incongruently dissolved in an acid solution. The overall finding indicated a potentially feasible technology in cadmium-laden sludge stabilization.

Determination of concentrations of Fe, Mg, and Zn in some ferrite samples using neutron activation analysis and X-ray fluorescence techniques

Mg-Zn ferrite is considered as one of the important materials with potential uses in many applications. In this work, samples of ferrite Mg_(1-x)Zn_xFe₂O₄ (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1) were synthesized by the sol-gel method for use in some hyperthermia applications. The composition and purity of the prepared samples hardly affected their properties. Therefore, the elemental concentration of these samples was measured by the X-ray fluorescence technique and thermal neutron activation analysis to check the quality of the prepared samples. The results of both methods were compared with each other and with the molecular ratios of the as-prepared samples. In addition, no existing elemental impurity, with considerable concentration, was measured.

Data files for ab initio calculations of the lattice parameter and elastic stiffness coefficients of bcc Fe with solutes

We present computed datasets on changes in the lattice parameter and elastic stiffness coefficients of bcc Fe due to substitutional Al, B, Cu, Mn, and Si solutes, and octahedral interstitial C and N solutes. The data is calculated using the methodology based on density functional theory (DFT) presented in Ref. (M.R. Fellinger, L.G. Hector Jr., D.R. Trinkle, 2017) [1]. All the DFT calculations were performed using the Vienna Ab initio Simulations Package (VASP) (G. Kresse, J. Furthmüller, 1996) [2]. The data is stored in the NIST dSpace repository (http://hdl.handle.net/11256/671).

Mechanism of Fluorescence Enhancement of Biosynthesized XFe2O4-BiFeO3 (X = Cr, Mn, Co, or Ni) Membranes

Ferrites-bismuth ferrite is an intriguing option for medical diagnostic imaging device due to its magnetoelectric and enhanced near-infrared fluorescent properties. However, the embedded XFO nanoparticles are randomly located on the BFO membranes, making implementation in devices difficult. To overcome this, we present a facile bio-approach to produce XFe₂O₄-BiFeO₃ (XFO-BFO) (X = Cr, Mn, Co, or Ni) membranes using Shewanella oneidensis MR-1. The perovskite BFO enhances the fluorescence intensity (at 660 and 832 nm) and surface potential difference (-469 ~ 385 meV and -80 ~ 525 meV) of the embedded spinel XFO. This mechanism is attributed to the interfacial coupling of the X-Fe (e^- or h⁺) and O-O (h⁺) interfaces. Such a system could open up new ideas in the design of environmentally friendly fluorescent membranes.

An electrochemical genosensor for Leishmania major detection based on dual effect of immobilization and electrocatalysis of cobalt-zinc ferrite quantum dots

Identification of Leishmania parasites is important in diagnosis and clinical studies of leishmaniasis. Although epidemiological and clinical methods are available, they are not sufficient for identification of causative agents of leishmaniasis. In the present study, quantum dots of magnetic cobalt-zinc ferrite (Co0.5Zn0.5Fe2O4) were synthesized and characterized by physicochemical methods. The quantum dots were then employed as an electrode modifier to immobilize a 24-mer specific single stranded DNA probe, and fabrication of a label-free, PCR-free and signal-on electrochemical genosensor for the detection of Leishmania major. Hybridization of the complementary single stranded DNA sequence with the probe under the selected conditions was explored using methylene blue as a redox marker, utilizing the electrocatalytic effect of the quantum dots on the methylene blue electroreduction process. The genosensor could detect a synthetic single stranded DNA target in a range of 1.0×10(-11) to 1.0×10(-18)molL(-1) with a limit of detection of 2.0×10(-19)molL(-1), and genomic DNA in a range of 7.31×10(-14) to 7.31×10(-6)ngμL(-1) with a limit of detection of 1.80×10(-14)ngμL(-1) with a high selectivity and sensitivity.

Comparison between magnetic force microscopy and electron back-scatter diffraction for ferrite quantification in type 321 stainless steel

Several analytical techniques that are currently available can be used to determine the spatial distribution and amount of austenite, ferrite and precipitate phases in steels. The application of magnetic force microscopy, in particular, to study the local microstructure of stainless steels is beneficial due to the selectivity of this technique for detection of ferromagnetic phases. In the comparison of Magnetic Force Microscopy and Electron Back-Scatter Diffraction for the morphological mapping and quantification of ferrite, the degree of sub-surface measurement has been found to be critical. Through the use of surface shielding, it has been possible to show that Magnetic Force Microscopy has a measurement depth of 105-140 nm. A comparison of the two techniques together with the depth of measurement capabilities are discussed.

The effects of surface spin on magnetic properties of weak magnetic ZnLa0.02Fe1.98O4 nanoparticles

In order to prominently investigate the effects of the surface spin on the magnetic properties, the weak magnetic ZnLa0.02Fe1.98O4 nanoparticles were chosen as studying objects which benefit to reduce as possibly the effects of interparticle dipolar interaction and crystalline anisotropy energies. By annealing the undiluted and diluted ZnLa0.02Fe1.98O4 nanoparticles at different temperatures, we observed the rich variations of magnetic ordering states (superparamagnetism, weak ferromagnetism, and paramagnetism). The magnetic properties can be well understood by considering the effects of the surface spin of the magnetic nanoparticles. Our results indicate that in the nano-sized magnets with weak magnetism, the surface spin plays a crucial rule in the magnetic properties.

Interface conditions during mixed-mode phase transformations in metals

A fast three-dimensional phase transformation model is formulated for the transformation from ferrite to austenite in low-carbon steel. The model addresses the parent microstructure, the nucleation behaviour of the new phase and the growth of the new phase. During the growth, the interface velocity of the ferrite grains is calculated using a mixed-mode growth model. The simulated transformation kinetics is compared with experimental kinetics for an Fe-C-Mn steel for four different cooling rates. In general, the model predicts the kinetics quite well. In addition, the mixed-mode character of the transformation is shown for the different cooling rates.