Surface Of Magnetite Nanoparticles Research Articles

Anionic magnetic nanosorbents immobilized with peptide aptamer for selective adsorption with bisphenol A

This study focused on synthesis of anionic magnetite nanoparticles (MNPs) immobilized with a bisphenol A (BPA)-specific peptide aptamer for selective BPA adsorption. The MNP surface was coated with anionic poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) to provide water dispersibility and stability. These nanosorbents, with a saturation magnetization value of 47 emu/g, responded well to the change in zeta potential and hydrodynamic size with varying dispersion pH. The aptamer loading capacity of particles was 0.12 mg/mg MNPs, and the nanosorbents exhibited a 47% BPA adsorption capacity. Importantly, they shown high selectivity in capturing BPA over structurally similar molecules.

Efficient Chlorostannate Modification of Magnetite Nanoparticles for Their Biofunctionalization.

Magnetite nanoparticles (MNPs) are highly favored materials for a wide range of applications, from smart composite materials and biosensors to targeted drug delivery. These multifunctional applications typically require the biofunctional coating of MNPs that involves various conjugation techniques to form stable MNP-biomolecule complexes. In this study, a cost-effective method is developed for the chlorostannate modification of MNP surfaces that provides efficient one-step conjugation with biomolecules. The proposed method was validated using MNPs obtained via an optimized co-precipitation technique that included the use of degassed water, argon atmosphere, and the pre-filtering of FeCl2 and FeCl3 solutions followed by MNP surface modification using stannous chloride. The resulting chlorostannated nanoparticles were comprehensively characterized, and their efficiency was compared with both carboxylate-modified and unmodified MNPs. The biorecognition performance of MNPs was verified via magnetic immunochromatography. Mouse monoclonal antibodies to folic acid served as model biomolecules conjugated with the MNP to produce nanobioconjugates, while folic acid-gelatin conjugates were immobilized on the test lines of immunochromatography lateral flow test strips. The specific trapping of the obtained nanobioconjugates via antibody-antigen interactions was registered via the highly sensitive magnetic particle quantification technique. The developed chlorostannate modification of MNPs is a versatile, rapid, and convenient tool for creating multifunctional nanobioconjugates with applications that span in vitro diagnostics, magnetic separation, and potential in vivo uses.

Magnetite-silica core-shell nanostructures: Application for photodynamic therapy

Magnetite nanoparticles have been synthesized with chemical co-precipitation. The surface of magnetite nanoparticles was coated with an inorganic silica layer by hydrolyzing and condensing tetraethyl orthosilicate. An XRD investigation supports the cubic inverse spinel structure of Fe3O4 nanoparticles. The average crystallite size of the magnetite nanoparticles produced by the peak broadening was 13 nm. The UV-visible spectrum of methylene blue-loaded magnetite-silica nanoparticles shows a strong hump at 657 nm. According to TEM examination, the nanoparticles are polydisperse and almost spherical in form.The average size of the nanoparticles is 14.39 nm plus 1.66 nm, and they have a polydispersity index of 0.12%.The size and shape of the core-shell particles are not uniform, according to a SEM examination. There is no distinguishing morphology in any sample.The magnetic results depicts the superparamagnetic behaviour of nanoparticlesmakes them suitable for photodynamic therapy.

Glyphosate/AMPA adsorption on magnetite under different conditions: The effect of pH and electrolytes

As a result of the frequent use, glyphosate (GLY) and its major metabolite, aminomethylphosphonic acid (AMPA), have emerged as ubiquitous environmental contaminants worldwide. Glyphosate, applied in agriculture, adsorbs on soil minerals, such as iron oxides, facilitating its fixation in soils and preventing leaching into groundwater sources. However, the adsorption capacity of various types of soils exhibits substantial variability. In this work the adsorption of GLY and AMPA on magnetite nanoparticles (MNPs) was studied under different conditions: at pH ∼ 6 and ∼ 8, and in the presence of 10 mmol/L NaCl, an indifferent electrolyte, and 10 mmol/L CaCl2, which contains a specific cation mainly present in soils. The pH-dependent zeta potential measurements revealed the difference between the effect of Na+ and Ca2+ ions on the charge state and aggregation of MNPs. The adsorption of GLY/AMPA shows significant pH dependence, with the bound amounts decreasing rapidly above pH ∼ 7 in both 10 mmol/L NaCl and CaCl2 solutions. The phosphonate adsorption capacity of MNPs, as determined from the fitting of the Langmuir isotherm equation, was approximately 0.35 mmol/g and 0,09 mmol/g at pH ∼ 6 and pH ∼ 8, respectively. The diverse bound amounts at different pHs are of environmental importance: under alkaline soil conditions, the mobilization of GLY may be more probable. GLY and AMPA bind to the surface of MNPs via complex formation at ≡Fe-OH sites, primarily involving phosphate groups, preferably at acidic pH, where the MNPs carry positive charges, and the near-surface concentration of phosphonate anions is higher due to electrostatic attraction. Furthermore, in the presence of Ca2+ ions, Ca-bridging occurs, as supported by the findings from the ATR-FTIR spectra. Additionally, it is worth noting that the complex formation between Ca2+ and phosphonates in the solution phase reduces the probability of Ca-bridge and surface complex formation, hindering the fixation of GLY/AMPA in soils.

Efficient Oil Spill Uptake Using Surface-Modified Magnetite Nanoparticles with PET Waste Derivatives.

This work deals with poly(ethylene terephthalate) waste as a precursor to synthesize new cross-linked poly(ionic liquids) (CLPILs). The newly synthesized CLPILs, VPCT-Cl and VPCT-AA, were used for magnetite nanoparticle surface modification, producing VCL/Fe3O4 and VAA/Fe3O4, respectively. The chemical structures of the CLPILs and surface-modified Fe3O4 were elucidated by Fourier transform infrared and X-ray diffraction. Additionally, the particle size, zeta potential (ζ), contact angle, and magnetic properties of VCL/Fe3O4 and VAA/Fe3O4 were investigated using different techniques. Furthermore, the performance of these nanoparticles for oil spill cleanup was evaluated using various influencing factors, e.g., the contact time and the Fe3O4/crude oil ratio. VCL/Fe3O4 and VAA/Fe3O4 showed excellent performance in oil spill cleanup. The data showed that the performance increased with the contact time and the Fe3O4 ratio. Furthermore, the reusability of VCL/Fe3O4 and VAA/Fe3O4 over four cycles was also explored. The reusability data indicated that reused VCL/Fe3O4 and VAA/Fe3O4 showed promising performance in oil spill cleanup.

Drug loading comparison of commercial ibuprofen on magnetite nanoparticles surface by UV–Vis spectrophotometry and acid-alkali titration by a factorial design of experiments

The drug efficacy for the pathologies treatments depends on several physicochemical properties of the drug. Among these, solubility is one of the most important and is directly related to the bioavailability of the drug. Ibuprofen is a popular drug used for the treatment of different diseases. However, its dissolution rate in aqueous media is limited, which causes undesirable adverse effects on the patient. One of the possibilities to solve this challenge is loading ibuprofen on the surface of the nanoparticles for drug delivery. However, some challenges related to complicated experimental procedures, expensive chemical precursors, the techniques for ibuprofen quantification, and the loading efficiency continue to be a problem. This work reports the synthesis of magnetite nanoparticles and the straightforward loading with commercial ibuprofen in a mixed ethanol/water solution without intermediate surfactants, stabilizers, or linkers. XRD, SEM, FT-IR, Magnetometry, UV–Vis Spectrophotometry, and DLS techniques allowed for determining the samples' structure, morphology, functional groups, magnetism, and agglomerate size. A complete factorial Design of Experiments allowed for comparing the encapsulation efficiency for two exposure and centrifugation times (20 and 40 min) by UV–VIS and Acid-alkali titration. The results suggest that the magnetic separation and centrifugation (< 2000 RPM) were inappropriate for nanoparticle decantation. This produces an underestimation of the ibuprofen adsorbed by the nanoparticles. Under our experimental conditions, 20 min is enough to achieve maximum encapsulation efficiency (14%) without surfactants or binders.

Green Synthesis of Magnetite Nanoparticles Mediated Fumaria officinalis L. Plant as Sustainable and Renewable Adsorbing Materials

Magnetite nanoparticles (Fe3O4) have been utilized to mediate Fumaria officinalis L., a plant known for its rich source of various phytogredients such as diterpenes, nor-diterpenoids, tri-terpenoids, flavonoids, and phenolic acids. These natural compounds act as capping, reducing, and stabilizing agents, offering an affordable and safer approach to synthesize nanoparticles in line with sustainable and eco-friendly concepts, such as green nanoparticles. The cost-effective synthesized nanoparticles were employed to adsorb Pb(II) from an aqueous solution. For investigating the surface characteristics of the adsorbent, a range of techniques were employed, including Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform Infrared Spectroscopy, and X-ray Diffraction. Fourier Transform Infrared (FT-IR) spectroscopy was specifically applied to discern the functional groups present within the compounds. To optimize the adsorption process and achieve the best removal efficiency (R%), several parameters, including pH, initial concentration, temperature, and contact time, were optimized using the Response Surface Methodology (RSM). The experimental results indicated that the Langmuir isotherm provided a well-fitted model, suggesting a monolayer of Pb(II) capping on the surface of magnetite nanoparticles, with a maximum adsorption capacity of 147.1 mg/g. Moreover, the kinetic findings demonstrated a strong alignment with the pseudo-second-order model. The computed (qe) and observed outcomes associated with the pseudo-second-order kinetic model exhibited a commendable concurrence, underscoring the model’s remarkable precision in forecasting the adsorption mechanism of Pb(II) within the examined parameters. The antioxidant activity and green nanocomposite properties were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and standard analytical methods. The phytochemical profile exhibited a total phenolic content of 596 ± 0.001 mg GAE/g dry weight and a total flavonoid content of 18.25 ± 0.001 mg QE/g dry weight. The DPPH radical’s inhibition showed potent antioxidant activity at various concentrations (44.74, 73.86, 119.791, and 120.16% at 200, 400, 600, and 800 μg/mL, respectively), demonstrating the potential of the plant as a natural capping and reducing agent during the green process of nanoparticle formation.

Systematically Designed Surface and Morphology of Magnetite Nanoparticles Using Monocarboxylic Acid with Various Chain Lengths under Hydrothermal Condition.

Hydrothermal synthesis of surface-modified magnetite nanoparticles (NPs) was performed in a batch reactor at 200 °C for 20 min while using monocarboxylic acid with various alkyl chain lengths (C6 to C18) as surface modifiers. The short-chain cases (C6 to C12) successfully gave the surface-modified NPs with uniform shape and magnetite structure, while the long-chain cases (C14 to C18) gave the NPs with nonuniform shape and two structures (magnetite and hematite). Additionally, the synthesized NPs were revealed to have single crystallinity, high stability, and ferromagnetic property, which were useful for hyperthermia therapy via various characterization techniques. These investigations would guide the selection guidelines for a surface modifier to control the structure, surface, and magnetic properties of surface-modified magnetite NPs with high crystallinity and stability, particularly for hyperthermia therapy applications.

Reduction of Oxidizable Pollutants in Waste Water from the Wadi El Bey River Basin Using Magnetic Nanoparticles as Removal Agents

Many of the current strategies for removing pollutants from water are based on nanomaterials and nanotechnology. Lower values of Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) in water results in reduction in the amount of oxidizable pollutants. We present a study on the reduction of COD and BOD5 in water from Wadi El Bey River (Tunisia), using magnetite nanoparticles (MNPs) and magnetic fields. The COD and BOD5 removal reached values higher than 50% after 60 min, with optimum efficiency at pH values of ≈8 and for MNPs concentrations of 1 g/L. The use of a permanent magnetic field (0.33 T) showed an increase of COD and BOD5 removal from 61% to 76% and from 63% to 78%, respectively. This enhancement is discussed in terms of the MNPs coagulation induced by the magnetic field and the adsorption of ionic species onto the MNPs surface due to Fe3O4 affinity.

Synergistic effect of silver NPs immobilized on Fe3O4@L-proline magnetic nanocomposite toward the photocatalytic degradation of Victoria blue and reduction of organic pollutants.

The surface of magnetite (Fe3O4) nanoparticles was subject to modification through the incorporation of L-proline (LP) by simple co-precipitation method in which silver nanoparticles were deposited by in situ method, thereby yielding the Fe3O4@LP-Ag nanocatalyst. The fabricated nanocatalyst was characterized using an array of techniques including Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller (BET), and UV-Vis spectroscopy. The results evince that the immobilization of LP on the Fe3O4 magnetic support facilitated the dispersion and stabilization of Ag NPs. The SPION@LP-Ag nanophotocatalyst exhibited exceptional catalytic efficiency facilitating the reduction of MO, MB, p-NP, p-NA, NB, and CR in the presence of NaBH4. The rate constants obtained from the pseudo-first-order equation were 0.78, 0.41, 0.34, 0.27, 0.45, 0.44, and 0.34 min-1 for CR, p-NP, NB, MB, MO, and p-NA, respectively. Additionally, the Langmuir-Hinshelwood model was deemed the most probable mechanism for catalytic reduction. The novelty of this study lies in the use of L-proline immobilized on Fe3O4 MNPs as a stabilizing agent for the in-situ deposition of silver nanoparticles, resulting in the synthesis of Fe3O4@LP-Ag nanocatalyst. This nanocatalyst exhibits high catalytic efficacy for the reduction of multiple organic pollutants and azo dyes, which can be attributed to the synergistic effects between the magnetic support and the catalytic activity of the silver nanoparticles. The easy recyclability and low cost of the Fe3O4@LP-Ag nanocatalyst further enhance its potential application in environmental remediation.

Oil Spill Cleanup Employing Surface Modified Magnetite Nanoparticles Using Two New Polyamines

Oil spills in marine environments are a serious environmental concern and using low-cost materials for oil spill cleanup is an emerging subject. In recent years, surface-modified magnetite nanoparticles (MNPs) have shown promising properties for oil spill cleanup due to their high performance, low cost, magnetic properties, and reusability. This study aims to modify the surface of magnetite nanoparticles (MNPs) using two new polyamines and employ them for oil spill remediation. First, tetraethylene glycol (TEG) was converted to the corresponding alkyl halide (AH). Next, two polyamines were synthesized via the alkylation of diamines, 1,11-undecanediamine (UD) and 1,5-pentanediamine (PD), yielding the corresponding AH-UD and AH-PD polyamines. Finally, AH-UD and AH-PD were applied to MNPs’ surface modification, yielding the corresponding surface-modified MNPs, AU-MNPs, and AP-MNPs. The performance of AU-MNPs and AP-MNPs for oil spill uptake (OSU%) was investigated using various MNPs-to-oil ratios at different contact times. Furthermore, the reusability of AU-MNPs and AP-MNPs was also investigated over four cycles. The results indicated that the OSU values of AU-MNPs and AP-MNPs were affected by MNPs’ ratios and contact time, where their OSU increased as their ratios and contact time increased. In addition, AU-MNPs showed a higher OSU than AP-MNPs, which could be ascribed to the longer alkyl chain in the polyamine (AH-UA) used for their surface modification compared to AP-MNPs. Furthermore, AU-MNPs and AP-MNPs reusability results exhibited effective OSU in four cycles with a relative decline with an increasing number of cycles.

Functionalized Magnetite Nanoparticles Using Two New Ionic Liquids for Efficient Oil Spill Cleanup

Recently, magnetite nanoparticles (MNPs) have gained great attention for oil spill cleanup due to their unique properties, e.g., high oil removal efficiency, high surface area, and response to an external magnetic field. The efficiency of MNPs for oil spill uptake can be enhanced by functionalizing their surface using different materials. Furthermore, the functionalization of MNP surface using these materials promotes their chemical stability. This study aims to functionalize the surface of magnetite nanoparticles (MNPs) using two newly synthesized hydrophobic ionic liquids (ILs) and apply them for oil spill cleanup. ILs were synthesized by the reaction of glycidyl-4-nonyl ether (GE) with fatty amines, either octadecylamine (OA) or dodecylamine (DA), to yield the corresponding amines, GEOA and GEDA, respectively. GEOA and GEDA were quaternized with acetic acid (AA) to produce the corresponding ILs, GEOA-IL and GEDA-IL. The produced ILs, GEOA-IL and GEDA-IL, were applied for the surface modification of magnetite nanoparticles (MNPs), producing surface-modified MNPs, GO-MNPs and GD-MNPs, respectively. GO-MNPs and GD-MNPs were characterized using Fourier transform infrared, X-ray diffraction, transmission electron microscopy, dynamic light scattering, contact angle, and vibrating sample magnetometer. Their oil removal efficiency (ORE) was investigated at different MNP : crude oil ratios ranging from 1 : 1–1 : 50. GO-MNPs and GD-MNPs showed high ORE even at low MNP ratios. Furthermore, GO-MNPs showed higher oil removal efficiency than GD-MNPs, which may be explained using GEOA-IL containing a longer alkyl chain for MNP surface modification in comparison to GEDA-IL. Furthermore, GO-MNPs and GD-MNPs displayed excellent reusability in five cycles, with a slight decrease in ORE with increasing cycles.

Removal of lithium from aqueous solutions by solid-phase extraction using sawdust loaded with magnetite nanoparticles and study of apoptosis, MDA and 8-OHdG caused by lithium toxicity in fish brain.

Lithium, which has a high industrial value, is an environmental pollutant of concern to those who work with lithium in industry as well as to the general public. Biological parameters such as MDA, 8-OHdG, apoptosis (caspase-3), and acetylcholinesterase (AChE) were studied to determine the toxic effects on the brain tissue of the model organism (Carassius auratus) exposed to high dose lithium. According to the results obtained, it was found that lithium exposure caused oxidative stress with an increase in MDA level over time and, accordingly, DNA damage and apoptosis occured in brain tissue. It was also found that a decrease in AChE activity was observed, and the high levels of MDA, 8-OHdG, and caspase-3 activity obtained in brain tissue supported this result. The solid phase extraction (SPE) method was used to effectively remove lithium, which has unfavorable effects on living organisms, from aqueous solutions. In this method, a sawdust loaded with magnetite nanoparticles (MNLS) was prepared as an adsorbent for solid phase extraction by a simple method, and it was characterized. Optimal conditions for the SPE process were defined and it was found that lithium could be removed from solution onto the MNLS surface with a high yield of about 96%. The results of the study are crucial for proposing a simple and applicable high performance method.

Fine-Tuning the Degree of Negative Charge and Carboxylate Grafting Density of Polymer-Coated Magnetite Nanoparticle

The surface of magnetite nanoparticle (MNP) was modified with poly(acrylic acid)(PAA)-poly(ethylene glycol) methyl methacrylate (PEGMA) (co)polymer to obtain water dispersible MNP with pH sensitive surfaces via atom transfer radical polymerization (ATRP) of tert-butyl acrylate (t-BA), followed by the t-BA group deprotection. Molar compositions of the (co)polymer were systematically varied, namely 100:0, 75:25, 50:50 and 25:75 of P(t-BA)/PEGMA, respectively, such that the grafting density of carboxylate groups on the MNP surface after the deprotection can be fine-tuned. Transmission electron microscopy (TEM) indicated that the MNP were spherical (ca.5-12 nm in diameter) with some nanoclustering observed. The roles of PAA and PEGMA affecting the hydrodynamic size and zeta potential of the nanocomposites observed via photocorrelation spectroscopy (PCS) were discussed. The percentages of the polymeric composition in the nanocomposites in each step of the reaction were determined via thermogravimetric analysis (TGA) and their magnetic properties were studied via vibrating sample magnetometry (VSM). These novel nanocomposites with pH sensitive surface and magnetically guidable properties might be advantageous for further conjugations either by covalent or ionic bonding with bioentities. HIGHLIGHTS Magnetite nanoparticle (MNP) coated poly(acrylic acid)(PAA)-poly(ethylene glycol) methyl methacrylate (PEGMA) (co)polymer were fabricated via ATRP The ratio of t-BA to PEGMA used in the copolymerization was studied The nanocomposites showed pH sensitive surface and magnetically guidable properties GRAPHICAL ABSTRACT

Experimental measurement and modeling of asphaltene adsorption onto iron oxide and lime nanoparticles in the presence and absence of water

Asphaltene precipitation and its adsorption on different surfaces are challenging topics in the upstream and downstream of the oil industries and the environment. In this research, the phenomenon of asphaltenes adsorption in the presence and absence of water on the surface of magnetite, hematite, calcite, and dolomite nanoparticles (NPs) was investigated. Five asphaltenes of different origins, four NPs as adsorbents and Persian Gulf water were used for three-phase (asphaltene/toluene solution + NPs + water) experiments. Characterization of asphaltenes and NPs was performed using Fourier transform infrared spectroscopic (FTIR), dynamic light scattering (DLS), elemental analysis, and field emission scanning electron microscopy (FESEM). Adsorption experiments were performed in two- (asphaltene/toluene solution + NPs) and three-phase systems. The results showed that the most effective parameters for asphaltene adsorption onto these NPs are the asphaltene composition, namely nitrogen content, and the aromaticity of asphaltenes. The significant effects of these parameters were also confirmed by the relevancy factor function as a sensitivity analysis. In the competition of asphaltene adsorption capacity by NPs, iron oxide NPs had the highest adsorption (Magnetite NPs > Hematite NPs > Calcite NPs > Dolomite NPs). From the results of the experiments in the presence of water phase, it could be pointed out that the asphaltenes adsorption onto the NPs was accompanied by a decrease compared to the experiments in the absence of water. The modeling also showed that physical adsorption has a significant contribution to the asphaltenes adsorption on the surface of iron oxides and lime NPs. The results of this research can assist in a better understanding of the asphaltene adsorption phenomenon and the role of iron oxide and lime NPs in solving this problem.

Surface-modified magnetite nanoparticles using polyethylene terephthalate waste derivatives for oil spill remediation.

This work aims at synthesizing new cross-linked poly ionic liquids, CPILs, VIMDE-Cl and CPIL, VIMDE-TFA, utilizing polyethylene terephthalate waste as a precursor and applying them to magnetite nanoparticles surface modification, producing surface-modified magnetite nanoparticles, SMNPs, VDCL/MNPs, and VDTA/MNPs, respectively. The structures of VIMDE-Cl and VIMDE-TFA, VDCL/MNPs, and VDTA/MNPs, were verified using different techniques. The particle sizes of SMNPs, VDCL/MNPs, and VDTA/MNPs, were evaluated with a transmission electron microscope and dynamic light scattering. The compatibility of VDCL/MNPs and VDTA/MNPs with crude oil components and their response to an external magnet were also measured using contact angle measurements and a vibrating sample magnetometer. The data confirmed the formation of SMNPs, nanosized structure, compatibility with oil components, and response to an external magnet. For that, VDCL/MNPs and VDTA/MNPs were applied for oil spill recovery using different SMNP : crude oil weight ratios. The impact of contact time on SMNPs' performance was also evaluated. The data indicated increased performance with an increase in SMNPs ratio, reaching maximum values of 99% and 96% for VDCL/MNPs and VDTA/MNPs, respectively, at SMNPs : crude oil ratio of 1 : 1. According to the results, the optimal contact time was 6 min, resulting in 89% and 97% performance for VDCL/MNPs and VDTA/MNPs at 1 : 4 SMNPs : crude oil ratio.

In Ukrainian

The aim of the work is to study the adsorption properties of nanosized magnetite (Fe3O4) and nanocomposites based on it capable of sorption of Hg2+ ions from aqueous solutions. The direction of research includes the synthesis of nanoscale single-domain magnetite as a magnetosensitive carrier, modification of its surface with a biocompatible coating. The following samples were synthesized for research: Fe3O4, Fe3O4/SiO2 and Fe3O4/DMSA (meso-2,3-dimercaptosuccinic acid), Fe3O4/SiO2/DMSA. Coatings known for their biocompatibility with the environment of a living organism were used to modify the surface of magnetite nanoparticles, in particular, tetraethoxysilane and DMSA. Adsorption of Hg2+ ions on the surface of magnetite and nanocomposites (NCs) was carried out in an aqueous medium in the concentration range С0 = 1,0 – 40,0 mg/l (g = 0,03 g, V = 5 ml, pH = 2,7 ) for 1 hour at room temperature. The concentration of Hg2+ ions before and after adsorption was determined photometrically in the form of monosubstituted dithizonate at a wavelength of 490 nm. The pHIIP value of the surface of the synthesized nanocomposites was determined, and the dependence of the sorption activity on the pH level and the isoionic point of the surface in the range of pH= 2 – 9 was established. To study the kinetics of sorption, a solution with a concentration of Hg2+ = 36 mg/l and pH = 2,7 was used, with a contact time of 15 – 180 minutes. The kinetics and isotherm of sorption were analyzed using kinetic equations and models that take into account the contribution of the chemical reaction to the sorption process. It was established that the kinetics of sorption of Hg2+ ions corresponds to the pseudo-second-order kinetic model. Sorption isotherms correspond to the Freundlich model. The obtained data can be useful in the creation of magnetically controlled sorption materials for the extraction of Hg2+ ions from aqueous solutions and biological fluids.

Green Synthesis of Unsaturated Fatty Acid Mediated Magnetite Nanoparticles and Their Structural and Magnetic Studies

The green, cost-effective and sustainable synthesis of nanomaterials has been a key concern of scientists and researchers. In this view, MNPs were prepared using a sapota plant leaf extract and the surface of the magnetite nanoparticles was engineered with unsaturated fatty acids. The first report on the effect of unsaturation on the size and magnetic properties of magnetite nanoparticles (MNPs), prepared by the co-precipitation method, has been studied by coating surfactants on MNPs based on their unsaturation from zero to three (lauric acid, oleic acid, linoleic acid, linolenic acid). The size effect and magnetic properties of MNPs coated with a surfactant have been studied in comparison with uncoated magnetite nanoparticles. After the surface modification of the magnetite particle, it is necessary to check whether the magnetic property has been restored or not. Therefore, the magnetic property was studied. The presence of a surfactant on the surface of MNPs was confirmed by Fourier-transform infrared spectroscopy (FTIR), which was later confirmed by scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The atomic structure was studied by X-ray diffraction (XRD) and the size of uncoated and surfactant-coated MNPs was determined by transmission electron microscopy (TEM) and the Scherrer equation by following XRD data. The magnetization property was analyzed by a vibrating sample magnetometer (VSM) at 10, 100 and 300 K and both bared and surfactant-coated MNPs exhibited a superparamagnetic nature at room temperature. The saturation magnetization (Ms) study shows that MNPs coated with a surfactant have a lower saturation magnetization value in comparison to uncoated NPs, confirming surface layering. Because the magnetic fluid has been stabilized in the aqueous medium, the double-layer model is expected to prevail.

Magnetite-Silver Core–Shell Nanoparticles: Synthesis, Characterizes, and Optical Properties

Fe3O4 and Fe3O4/Ag core–shell nanocomposite powders were synthesized via the co-precipitation method. The structure, microstructure, magnetic, and optical properties of Fe3O4/Ag and Fe3O4 were studied. XRD patterns and UV–Vis spectra showed that nanostructure Fe3O4 and Fe3O4/Ag particles were successfully synthesized. AFM and MFM mode micrographs of Fe3O4 and Fe3O4/Ag powders confirm the formation of Fe3O4 particles in the nano-scale range. Both Fe3O4 and Fe3O4/Ag composite powders represented the superparamagnetic behavior due to the formation of nanosized Fe3O4 particles. Furthermore, in-situ synthesis of Ag on the surface of magnetite nanoparticles increased the particle size, resulting in a decrease in saturation magnetization. Moreover, based on the Maxwell-Garnet effective medium theory, a theoretical model was developed to determine the optical properties of suspended core–shell nanoparticles. A very good agreement was found between the theoretical and experimental results. In addition, the local electric field in the particles, evaluated using the numerical finite element method, showed that the electric field in the magnetite core might be amplified up to 20 times at the symmetrical SPR wavelength mode, depending on the silver shell thickness.

As (III) removal using superparamagnetic magnetite nanoparticles synthesized using Ulva prolifera − optimization, isotherm, kinetic and equilibrium studies

In this study, magnetite nanoparticles (MNPs) were synthesized using the seaweed – Ulva prolifera, an amply found marine source in the Western coastal regions of India. The surface and other properties of MNPs were characterized by many sophisticated methods. Spherical nanoclusters were observed in the FESEM image and iron and oxygen elements were seen in EDS results. XRD peaks were consistent with magnetite standards and MNPs had good crystallinity. FTIR portrayed the specific signals for MNPs and TGA profile ascertained the thermal stability. Magnetic saturation of 41.84 emu/g with negligible hysteresis loop substantiated the superparamagnetism. XPS pointed out the presence of Fe and O with oxidation states specific for MNPs, and the results were consistent with EDS. BET revealed a high specific surface area (144.98 m2/g) of MNPs with mesopores. The synthesized MNPs were used as nanoadsorbent for the removal of As (III) from aqueous solution. The central composite design was used for optimizing As (III) adsorption on MNPs. The optimum conditions were found out as 97.5% at pH: 9, rotation speed: 150 rpm, time: 90 min, and MNPs dosage: 1.15 g/L. The adsorption process fitted in a better way with the Langmuir isotherm and pseudo-second-order model. The highest adsorption capacity was 12.45 mg/g, which is substantially larger than the documenter reports. The spontaneous and endothermic nature of adsorption were ascertained from thermodynamic studies. The results suggested that the synthesized MNPs using the extract of U. prolifera could be alternative nanoadsorbents for eliminating toxic heavy metals from waste streams.