Papers by Keyword: Magnetic

Abstract: One of the emerging alternatives to surfactants in crude oil dehydration is the application of nanoparticles. This review aims to assess the recent progress in the application of nanoparticles for the chemical demulsification of water-in-oil and to provide knowledge gaps for future research. This review covers the nanomodification of commercial demulsifiers and the demulsification performance of magnetic and nonmagnetic nanoparticles, along with their possible mechanisms and factors that affect their dehydration efficiency. The addition of nanoparticles improves the dehydration performance of commercial demulsifiers by improving their wettability and interfacial activity. The advantage of magnetic nanoparticles is their rapid response to a magnetic field, which allows them to be recoverable. For nonmagnetic nanoparticles, their advantage is their environmental friendliness, biocompatibility, and cost-effectiveness. Nanoparticles were able to dehydrate emulsions by modifying the interfacial properties and possibly through adsorption of asphaltenes. Factors such as dosage, temperature, pH, salinity, water content, surfactant concentration; and nanoparticle wettability, and surface chemistry significantly affect the demulsification performance. The application of nanoparticles as demulsifiers is still on a laboratory scale. However, studies on toxicity and proper handling may increase interest for field application. Studies are encouraged on the exact mechanism on the reduction of interfacial tension.

Abstract: In this paper, a Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite with a weight ratio of 1:9 has been successfully created. The Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ was synthesized in HEM for 35 hours before sintered at 1000°C for 5 hours. The Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite was characterized using XRD for phase formation, crystal structure, and lattice parameters. Based on the XRD results, the Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite has two phases with different crystal structures. SEM characterization for surface morphology and particle size. SEM results show heterogeneous particles, but the particle size is not uniform at 0.2-0.6 µm. Measurements of the dielectric constant and dielectric loss are shown as a function of frequency. VSM is used to characterize samples magnetically. The VSM results show ferromagnetic behaviour in the Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite with the value of Mr, Ms, and Hc are about 20 emu/g, 40.769 emu/g, and 4.08 kOe, respectively.

Abstract: LiFe(P,Si)O₄ is a material that belong to parent compound of LiFePO₄ widely known as cathode material for lithium-ion battery (LIB). Previous study reports that electrochemical performance of LiFePO₄ can be improved by silicon (Si) substitution to the phosphorus (P) site. The sample was obtained via a solid-state synthesis route with the amount of Si doping to the P site is ∼3%. The electrochemical performance of silicon substituted LiFePO₄ has been widely studied in other report whilst the magnetic properties is still less explored. Here we investigate the magnetic properties of LiFe(P,Si)O₄ using superconducting quantum interference device (SQUID) and muon spin relaxation (µSR). The two measurements display a good agreement result showing two anomalies at the temperature of ∼27 K and ∼52 K that represent the Neel Temperature (Τ_N) of Li₂FeSiO₄ and LiFePO₄, respectively. The presence of Li₂FeSiO₄ that is also a candidate of cathode of LIB has been confirmed by X-ray Diffraction (XRD). Based on the current study, there is no alteration of Τ_N on LiFePO₄ phase due to Si doping.

Abstract: We have studied magneto-conductive and magnetic properties of La_1-xSr_xMnO₃ (LSMO) thin films on a-SiO₂ substrates produced by the metal organic decomposition (MOD) method. LSMO thin films for x = 0, 0.15 and 0.3 have been produced in a pure O₂ gas atmosphere. Although LaMnO₃ (LMO) single crystal is an antiferromagnetic insulator (AFI), LMO thin films we have produced show ferromagnetic metal (FM) properties for suitable heat treatment conditions. We consider that the excess of O^2- ions in LMO thin films produced in a pure O₂ gas atmosphere induces the strong hole self-doping into those and the LMO thin films change from AFI to FM. Whereas, the ordinary hole doping is also occurred in LSMO thin films at x > 0. Thus, the carrier doping for LSMO thin films at x > 0 is caused by the hole self-doping by O^2- ions and the ordinary hole doping by the replacement of La³⁺ ions by Sr²⁺ ones. To investigate the crystallographic and surface structures of the LSMO thin films, X-ray diffraction and SEM measurements have been performed, respectively. From the X-ray diffraction measurement, we have found that all LSMO thin films have perovskite structure and are polycrystalline. From the SEM measurement, we have seen that the LSMO thin films are formed of the aggregation of LSMO fine particles. Electrical resistivities (ERs) and magneto-resistivity (MR) ratios of the LSMO thin films have been measured on the temperature dependence (4K-300K). From MR ratio measurements, the coercive forces of them have been obtained as a function of temperature, and the Curie temperatures have been estimated from the temperature dependences of the coercive forces. We have discussed the origin of the magneto-conductive and magnetic properties of LSMO thin films.

Abstract: Iron is a ubiquitous element found on Earth's crust, existing in various forms, such as Magnetite (Fe₃O₄) and Hematite (α-Fe₂O₃). Magnetic iron oxide nanoparticles (MIONPs) have become increasingly popular because they possess unique properties such as high surface area to volume ratio, super-paramagnetic properties, photocatalytic properties, and economical synthesis methods. This study produced MIONPs using the co-precipitation method, stabilized by a molybdenum magnet. Two soluble iron salts (FeCl₃.6H₂O and FeSO₄.7H₂O) were reacted with 5N NH₄OH solution at 80 °C in a nitrogen atmosphere. The MIONPs had a high saturation magnetization of 74.2emu/g, good crystallinity with crystalline spinel structured magnetite phase of iron oxide, high thermal stability depicted by 2.09 wt. % weight loss, and small particle sizes (6-25 nm). FTIR revealed a high-intensity peak at 546.28 cm^-1, attributed to the Fe-O stretching bond. Furthermore, the study showed that the co-precipitation method could be used to produce nanoparticles with a wide range of properties that could be used for various applications. It is a promising solution for producing stabilized magnetic nanoparticles since it uses non-toxic reagents and a straightforward, secure technique. Therefore, it may be used to synthesize nanoparticles for targeted treatment, magnetic resonance imaging, drug delivery, water treatment purposes and environmental remediation.

Abstract: Nanocrystalline materials have different properties compared to materials with microcrystalline grains. Nanocomposites, as a subdivision of nanomaterials, have different magnetic properties for each individual constituent. In the paper, a series of nanocomposite materials from the sphere of W ferrites are developed by mechanical grinding. Mixtures of commercial BaO and α-Fe₂O₃ powders, in the micron range, were used. The commercial powders were mechanically ground in order to reach the nanometric range. The use of suitable grinding parameters for ceramic powders led to the discovery of the nanometric range in a not very long time. An important parameter, which was used in the current research, was wet grinding which is a more suitable method for obtaining finer powders than dry grinding. Dividing the materials as finely as possible ensures a better reactivity due to the free valences of the ions on the surface of the granules and due to the fact that the number of contact points and the contact surface are much larger than in coarse-grained materials. The powders were unilaterally compacted, using a cylindrical die with an inner diameter of 15 mm. A resistive heating device was designed and built in order to assure the sintering process of the samples. Before resistive sintering, a thermal simulation of the heating process was carried out to see the distribution of the thermal field in the samples at different temperatures. According to the simulation, the optimal heating temperature was chosen. The sintered samples were analyzed from the point of view of the magnetic properties and it was found that the samples with the granulation in the nanometric range have higher magnetic characteristics than those in the micron range.

Abstract: Graphenic carbon (GC) has been successfully synthesized from biomass (coconut shell charcoal) using the liquid phase exfoliation method. The dopants, in the form of light atoms such as boron (B-GC), were introduced with the aim of improving their magnetic properties. X-ray diffraction was used to identify the GC and B-GC, and the results show broad peaks around 24° and 43°, indicating the presence of graphene-like carbon structure. The bonding structure was also analyzed using X-ray photoelectron (XPS). It reveals the main bonds in GC consist of sp², sp³, and C=O. While the B-GC sample shows an additional bond, namely the B-C bond, as an indicator of the successful doping process of B into the GC structure. Both GC and B-GC show weak room temperature ferromagnetism. Furthermore, these findings show that introducing boron atoms into the graphenic structure can improve magnetization.

Abstract: The aim of this study was to compare the synthesis process of magnetic silica nanoparticles (Fe-SNP) through the analysis of X-ray Diffraction (XRD) results. Fe₃O₄ magnetic nanopowders was synthesized by ultrasonic assisted co-precipitation and Fe-SNP was synthesized by direct mixing method of sodium silicate (Na₂SiO₃) and magnetite (Fe₃O₄) and the sol-gel method. Silica sludge was used as a silica source from Indonesia geothermal power plant waste. The synthesized of Fe-SNP is the functionalization of Fe₃O₄ with silica. Variations concentration of Na₂SiO₃ is used for the direct mixing method and variations of Fe₃O₄ form is used for the sol-gel method. Particles formed and particle size were characterized by XRD. The XRD results showed that there is no SiO₂ phase in the sample synthesized by direct mixing method while two phases of SiO₂ and Fe₃O₄ were found in the sample synthesized by sol-gel method. The size of the Fe₃O₄ nanoparticles calculated with Scherer’s formula and it obtained 19.9 nm, while the Fe₃O₄ nanoparticles with the addition of 20 mL and 6 mL Na₂SiO₃ concentrations were 6,53 nm and 10,23 nm. For the sol-gel method the size of Fe₃O₄ nanoparticles obtained was 11,03 using Fe₃O₄ powders and 9,86 using Fe₃O₄ solutions.

Abstract: This research synthesized natural magnetic particles/chitosan/gold nanoparticles composites (NMP/Chi/AuNPs) using a green method. AuNPs were synthesized using chitosan as a reducing agent and stabilizer in one step. The obtained AuNPs were characterized using UV-Vis spectrophotometer and TEM. Results showed that AuNPs were spherical with an average of 14.9 nm and absorbed at visible light (~530 nm). Then, AuNPs were impregnated on NMP/Chi at room temperature. The impregnation results were characterized using FTIR, XRD, and TEM. In the IR spectra of NMP/Chi and NMP/Chi/AuNPs, the NH bending vibrations of NH₂ are shown at 1604 and 1631 cm^-1. The NMP/Chi/AuNP showed a decrease in intensity and the peak shift to 1395 cm^-1, stretching vibration of C-O from primary alcohol group. Fe-O vibrations of Fe₃O₄ in NMP/Chi and NMP/Chi/AuNPs are shown at 566 and 583 cm^-1. The intensity peak shift and decrease indicate an interaction between AuNPs and NMP/Chi. The results of the XRD NMP/Chi/AuNPs characterization showed that the diffraction peak at 2Ө 35.44° decreased in intensity, resulting in a decrease in crystallinity caused by impregnated AuNPs and the destruction of hydrogen bonds. The new diffraction peak at 2Ө 38.24° indicates the presence of AuNPs. TEM analysis showed an amorphous layer around the NMP, and the average size of AuNP in the NMP/Chi/AuNP composite was 23.01 nm.

Abstract: Inorganic nanocarriers for a decade have increased interest in nanotechnology research platform as versatile drug delivery materials. The utility of the inorganic nanocarriers for delivery of therapeutic agents is attributed to their unique properties such as magnetic, photocatalytic nature and the ability to exhibit surface functionalization. Herein, we review the surface functionalization and delivery utility for natural therapeutics exhibited by inorganic nanocarriers mostly focusing on their magnetic, photocatalytic and the plasmonic properties. The review also highlights the influence of electronic property of inorganic surface on functionalization of ligand based natural therapeutic agents. Improvement of stability and therapeutic potential by formation of nanocomposites are detailed. Furthermore, we suggest improvement strategies for stability and toxicity reduction of inorganic nanoparticles that would potentially make them useful for clinical application as therapeutic delivery tools for treatment of various diseases.