1,720,985 research outputs found
Adsorption of Copper Ions on the Surface of Multilayer Ti3C2Tx MXenes with Mixed Functionalization
No full textNowadays a new class of two-dimensional materials, MXenes, is attracting considerable attention as nanoadsorbents for the removal of heavy-metal ions from water. Pollutants such as copper and other heavy metals possess a negative impact on human health and the quality of natural ecosystems when their concentration exceeds an acceptable limit, which makes it urgent to develop cheap and effective methods to reduce the concentration of such pollutants. In this work we study the adsorptive properties of Ti3C2Tx MXenes with mixed functionalization by –O, –F, and –OH surface groups in relation to copper Cu(II) ions. Herein, multilayer MXene particles are investigated, since their yield is much greater than that of single-layer particles when using standard synthesis methods, and the experimental results are compared with previously published data for single-layer MXenes. It is established that, at low concentrations (below 50 mg/L), multilayer Ti3C2Tx MXenes demonstrate a comparable adsorption capacity of ~102 mg/g which makes it possible to use them for practical applications
Adsorptive Properties of Ti3C2Tx MXenes with Optimal Surface Functionalization by (‒O, ‒F) Groups
No full textNanoadsorbents, including 2D MХenes, are being actively studied as materials for the removal of heavy metals from water. Adsorption is a cheap and effective way to reduce the pollution level with such-kind toxic substances. Ti3C2Tx MXenes are one of the most promising materials in this field, due to their large specific surface area rich in adsorption centers. Additionally, the composition of this material can be optimally selected to ensure the maximum adsorption efficiency, for example, by controlling their surface functionalization. Density functional theory (DFT) modeling is one of the most effective methods for studying and predicting the adsorption properties of MXenes. In this work, the DFT approach is used to determine the adsorption energies (Eads) of mercury and iron ions on the surface of Ti3C2O2 and Ti3C2F2 MXenes. It is found that the maximum adsorption energy (Eads = –3.59 eV for Fe and –0.357 eV for Hg) is exhibited by MXenes with oxygen surface functionalization. Also, the work describes the synthesis and characterization of Ti3C2Tx MXenes with a predominant content of –O functional groups. Characterization of the material includes the study of its optical properties, i.e., absorption spectra: their analysis is a simple way to subsequently detect the content of MXenes in treated water. It is found that Ti3C2Tx MXenes have a light-absorption peak at a wavelength of 795 nm, and the dependence of the intensity of this peak on the concentration is linear in the range from 10 to 100 μg/mL, which is convenient for subsequent use in optical detection
Study of Magnetic Interactions in a Composite with a Mixture of γ-Fe2O3 and CoFe2O4 Nanoparticles
No full textModification of the Codeposition Method for the Synthesis of Iron-Oxide Nanoparticles with a High Magnetization Value and a Controlled Reaction Yield
No full textAbstract: The structural and magnetic properties of magnetic iron-oxide nanoparticles obtained by a modified codeposition method with reduced concentrations of metal cations in the initial solution are studied, and an approach with ultrasonic stirring of the solution is developed. It is found that ultrasonic synthesis leads to the formation of nanoparticles with a high content of the crystalline phase compared to particles obtained using the classical approach with mechanical stirring, which produces nanoparticles of a smaller size and with a larger volume fraction of the X-ray amorphous phase. Nanoparticles obtained by the modified method have a high saturation magnetization, and therefore the approach can be adapted to obtain magnetic nanocomposites by introducing nanoparticles of a different nature into the solution, which will act as a nucleus for growth of the magnetic phase
Hard Magnetic Properties of Co-Rich Microwires Crystallized by Current Annealing
No full textMicromagnets in the form of microwires have become a subject of interest in various applications including magnetic field bias elements in miniature actuators, sensors, and manipulators. While the preparation of hard magnetic microwires with sufficiently high magnetization is a difficult task, it can be achieved by using specific crystallization techniques. We present a technique for the fabrication of micromagnets via controlled heat treatment of amorphous microwires using an electrical current. This crystallization technique converts a Co-rich microwire from a soft to a hard magnetic material. A large increase in coercivity (up to 580 Oe) is obtained after optimal current annealing (100 mA during 30-60 min). The crystallization consists of fine grains of mainly hcp-Co with an average size of 74 nm
Effect of Doping on the Magnetic and Sorption Properties of Cobalt-Ferrite Nanoparticles
No full textThe use of magnetic nanoparticles as sorbents for wastewater treatment in various industries can improve the efficiency of this process and reduce the impact of humans on the environment. Therefore, the development of a cost-effective method for the preparation of magnetic nanoparticles with optimal physical–chemical properties, especially high saturation magnetization, is a crucial task in current research. In this study, we use the sol–gel-citrate self-combustion method to synthesize a series of spinel ferrite magnetic nanoparticles with different chemical compositions. A set of cobalt-ferrite nanoparticles with the partial substitution of cobalt by zinc and manganese and iron by aluminum is obtained. Among the investigated samples, the zinc-doped cobalt-ferrite nanoparticles show the highest saturation magnetization of 88 A m2/kg at room temperature. Surface modification of the synthesized materials with polyethylene glycol and sodium dodecyl sulphate can improve their colloidal stability and as a consequence increase their sorption capacity
New Multiferroic Composite Materials Consisting of Ferromagnetic, Ferroelectric, and Polymer Components
No full textThe multiferroic ferroelectric-ferromagnetic-polymer composite systems, consisting of ferroelectric PZT particles, ferromagnetic NdFeB (or barium ferrite) particles, and silicone matrix, were investigated. The influence of the polymer Young's modulus on the properties was determined. The coercivity of elastomers with the same magnetic fillers in different matrices differs by a factor of 7. The influence of magnetic field on electric properties was investigated. Magnetodielectric effect in three-phase samples was found to be non-monotonic. The influence of electric field on magnetic properties of elastomers was investigated. The magnetoelectric effect under an applied electric field in new three-phase material was discovered
SDS-Modified Iron Oxide Magnetic Nanoparticles for Removing of Methylene Blue from Aqueous Solution
No full textAbstract: It is shown that surface-modified magnetic iron oxide nanoparticles with an average size of about 10 nm have a high adsorption capacity for the sorption of pollutants from wastewater. A considerable advantage of using magnetic materials is their ability to extract the sorbent using an external magnetic field, making the purification process more efficient. It is found that anionic sodium dodecyl sulfate increases the electrostatic attraction to the cationic compound Methylene Blue, preventing the aggregation of nanoparticles and increasing the active surface. The sorption capacity of magnetic nanoparticles after surface functionalization grew by a factor of 250, relative to unmodified iron oxide nanoparticles. The mechanism and kinetic parameters of sorption are determined, along with the optimum conditions for increasing the efficiency of the sorption process
Magnetorheological foams for multiferroic applications
No full textComposite rheological materials based on ferroelectric porous structure and either magnetic elastomer or fluid filler were investigated. Ferroelectric porous structure was prepared using silicone matrix and ferroelectric PZT microparticles. Different types of liquid magnetic mixtures were placed into the porous foam like in a sponge. The influence of external electric field on the magnetic properties of such composites was detected by vibrating sample magnetometer with added voltage source. Coefficient of inverse magnetoelectric transformations of the sample with elastic filler was found to depend on magnetic field. It maximum value for the sample with iron microparticles was found to be ∼36 μG cm/V. Comparing the properties of the ferroelectric foam with ferrofluid and magnetic elastomer, we propose a qualitative model of magnetoelectric effect associated with deformation effects in components and with magnetization mechanism
Effect of PEG nanoparticle surface coating on the magnetic and structural properties of CoFe2O4/PVDF composites
No full textThis research focuses on the impact of polyethylene glycol (PEG) coating on the magnetic and structural properties of composites consisting of an electroactive polyvinylidene fluoride matrix and CoFe2O4 nanoparticles. The intrinsic piezoelectric and magnetic properties of the constituents fundamentally determine the properties of composites, but the microstructure and particle packing of the composite are equally crucial for enhancing magnetoelectric coupling. Our findings reveal that PEG coating promote a more uniform spatial distribution of particles agglomerates within the polymer matrix, which achieved by strengthening of the interfacial coupling and reducing of the filler density during the solvent casting process. Together with reduced agglomerates size from an average of 28 ± 3 μm to 17 ± 1 μm uniform spatial distribution leads to decrease of magnetic dipolar interactions from ∼ 900 Oe to ∼ 800 Oe - tendence confirmed from the first-order reversal curve (FORC) analysis. Additionally, the root mean square roughness of the composite surface decreases from 185 nm to 74 nm, indirectly confirming increased sample uniformity. Local electrical properties, measured through Piezoresponse Force Microscopy (PFM), show a substantial enhance of the local piezoelectric response by ∼ 40 %. Results can be used for the enhancing of magnetoelectric effect in biocompatible materials, utilized at low frequency
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