Papers by Keyword: Co-Precipitation

Abstract: Calcite is a widely available biocompatible material and produced naturally by marine seashells. It can function as a host of bioimaging fluorophores or photoluminescent lanthanides. Eu (II) was incorporated into calcite, a polymorph of calcium carbonate (CaCO₃), through co-precipitation to explore the photoluminescence (PL) of Eu-doped calcium carbonate. Eu (II) was incorporated at different mass percentages from 0.625 to 20% at temperatures not exceeding the decomposition of both CaCO₃ and europium carbonate (EuCO₃). The temperature and transformation of Eu were tracked and showed that at a curing temperature of 400°C, for 20% Eu, Eu (II) ions were initially incorporated into the calcium positions in calcite. As the temperature increased to 450°C, the oxidation of Eu (II) and formation of europium sesquioxide (Eu₂O₃), was observed. The reaction was confirmed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mass spectrometry (MS). Eu³⁺, with a smaller crystal radius, was preferentially incorporated into the calcite instead of the larger Eu²⁺ due to the reduction in the lattice parameters and crystal volume. PL results on the samples further showed red luminescence of Eu³⁺ at excitation and emission peaks of 390 and 619 nm, respectively instead of the blue luminescence of Eu²⁺.

Abstract: Although magnetic nanoparticles have been widely studied, limited research has compared different ferrite types and synthesis routes for use in hyperthermia-based bioactive glass applications. This study aims to synthesize magnetic materials from two types of ferrites: magnesium ferrite (MgFe₂O₄) and zinc ferrite (ZnFe₂O₄). These ferrite nanoparticles were synthesized using two distinct methods; the conventional solid-state reaction and the co-precipitation method in order to identify the optimal synthesis route and the most suitable type of magnetic material for hyperthermia treatment. The data demonstrated that MgFe₂O₄ powder with synthesis by using the solid-state method consistently presented higher value of magnetic properties compared to those synthesized by co-precipitation method under higher calcination temperature. Moreover, ZnFe₂O₄ powder was found to be unsuitable for use as a precursor in hyperthermia treatment because of its structure typically leads to antiferromagnetic or superparamagnetic behavior. The effect of MgFe₂O₄ containing in bioactive glass was investigated. The oxide precursors of bioactive glass were mixed with varying amounts of MgFe₂O₄ and subsequently melted to form glass at 1400 °C. The phase formation presented SiO₂ was the dominant phase and coexisted with Na₂CO₃, MgSiO₃, Fe₃O₄, Na₂Ca (PO₄)₂SiO₄, Ca₂SiO₄, and Na₄Ca₄Si₆O₁₈. However, the MgFe₂O₄ phase was not observed in all of glass-ceramic samples. This may be due to MgFe₂O₄ decomposed during the high-temperature melting process at 1400 °C. Nevertheless, these magnetic bioactive glass ceramic samples exhibited magnetic properties, which were attributed primarily to the presence of Fe₃O₄.

Abstract: Ni_1-2xMg_xCu_xO and Ni_1-2xMg_xRu_xO nanoparticles (x = 0.005, 0.01, 0.02, 0.04, 0.08) were synthesized by the chemical co-precipitation method using salt chloride precursor and EDTA as a capping agent.The present work compares the impact of (Mg, Cu) and (Mg, Ru) co-dopants on the dielectric properties of NiO within a frequency range 0.1 -8 MHz and various dopant concentrations x = 0, 0.005, 0.01, 0.02, 0.04, 0.08. The dielectric properties and phase formation were investigated via an impedance analyser and XRD, respectively. X-ray diffraction patterns confirm the successful synthesis and crystallization of all Ni_1-2xMg_xCu_xO and Ni_1-2xMg_xRu_xO nanoparticles in the fcc structure except for Ni_0.92Mg_0.04Ru_0.04O and Ni_0.84Mg_0.08Ru_0.08O nanoparticles confirming a secondary RuO₂ pahse. Observed and calculated data from the impedance analyzer showed higher dielectric constants, ac conductivity, energy loss, and refractive index values for Ni_1-2xMg_xCu_xO than for Ni_1-2xMg_xRu_xO nanoparticles. However, the impedance values of (Mg, Ru) dual-doped NiO nanoparticles were higher compared with (Mg, Cu) dual-doped NiO nanoparticles. Both samples showed a decrease in dielectric constants, impedance, loss tangent, and refractive index as frequency increased (0.1-7.5MHz), with a vice versa behavior as dopant concentration rose, except for the impedance. Hence, Ni_1-2xMg_xCu_xO and Ni_1-2xMg_xRu_xO nanoparticles are good candidates for electrical and optical applications.

Abstract: Effect of the synthesis temperature on strontium-modified cobalt ferrite nanoparticles using co-precipitation method has been conducted. Molarity composition of strontium is 10%, chosen to substitute in the cobalt ferrite nanoparticles. Synthesis temperature treatment (75 °C, 85 °C, and 95 °C) is tuned the crystalline structures and magnetic properties of the cobalt ferrite nanoparticles. XRD result showed that the pattern of characteristics appropriates ICDD 22-1086, which describes that all peaks are pristine cobalt ferrite. Furthermore, crystallite size decreases with increasing synthesis temperature, i.e., 25.32 nm, 23.55 nm, and 22.65 nm at the temperatures of 75 °C, 85 °C, and 95 °C, respectively. FTIR obtained shows an absorption band at around 590 cm^-1 (tetrahedral site) and 387 cm^-1 (octahedral site), which is absorption from the original cobalt ferrite. VSM test also revealed changing magnetic properties with synthesis temperature treatment. In addition, squareness ratio showed that the magnitudes were greater than 0.5, which indicates single-domain magnetic. Hence, the adjustment of the synthesis temperature at 95 °C has the highest potential to advance applications such as photocatalytic and/or antibacterial due to its smallest crystallite size.

Abstract: Calcium substituted strontium M-Type hexaferrites are synthesized at different calcium concentrations by co-precipitation method. During synthesis process, PH value of 11 is achieved and solution is heated at 70 °C for 3 hours to form gel followed by drying process at 80 °C for 5 hours. Synthesized samples are then sintered at 650 °C for 4 hours at ramp rate of 10 °C/min. XRD analysis reveals that strontium M-Type hexaferrites at all calcium concentrations exhibit single phase hexagonal crystal structure. Change in density is observed for samples sintered at 800 °C as compared to samples sintered at 650 °C due to increase in temperature. SEM shows that the average particle size of strontium M-Type hexaferrites is greater at lower calcium concentration and smaller at higher concentrations. The average particle size varies from 530 nm to 345 nm for different calcium concentrations and fine particle sizes are achieved at all calcium concentrations. EDX results indicate that stoichiometric ratio is properly maintained according to samples composition and no extra peak of impurity or other element is detected in EDX spectrum. According to LCR measurement, pure strontium M-Type hexaferrites exhibit high dielectric constant at lower frequencies as compared to calcium substituted M-Type hexaferrites at different concentrations. Pure strontium M-Type hexaferrites have higher conductivity which might be due to presence of extra Fe³⁺ ions at crystal lattice sites. At lower frequencies pure strontium M-Type hexaferrites have higher conductivity and higher tangent loss at lower frequencies as compared to calcium substituted M-Type hexaferrites. While in the frequency range of 200 Hz to 300 Hz calcium substituted M-Type hexaferrites exhibit higher tangent loss.

Abstract: Waste eggshell powders with a particle size of less than 0.315 μm were surface treated with vinyltrimethoxysilane. XRD, FT-IR, BET and SEM analyses were used to determine the surface characteristics of eggshells before and after silane treatment. The preparation of films of unplasticized suspension polyvinyl chloride with untreated and silane-treated eggshells was done by co-precipitation of solutions from cyclohexanone. The tensile properties of obtained films containing vinyltrimethoxysilane-treated eggshell powders were investigated and analyzed relative to the compositions with untreated powders.

Abstract: Room temperature-built gas sensors were fabricated from graphene oxide (GO), pristine and doped SnO₂ nanostructures. The as-synthesized green carbon derivative (GO) nanomaterials were prepared from waste plastic precursor using Modified Hummer’s methodology. Pristine SnO₂ and GO-SnO₂ nanocomposite were synthesized employing a wet synthesis technique known as co-precipitation. The as-prepared nanoparticles were investigated for structural crystallographic and morphological features using X-ray diffractometry (XRD) and Transmission electron microscopy (TEM) analytical techniques. High-angle annular dark field (HAADF) and elemental quantifications of the nanopowders were investigated with the Energy dispersive X-ray spectroscopy (EDX). Textural features were determined with the assistance of Brunauer-Emmett-Teller (BET) analyzer. Thermogravimetric analysis (TGA) was performed to ascertain the material stability and degradability of the synthetic materials. Functional group and bond structure analysis was conducted using Fourier-transform infrared (FTIR) spectroscopy. Gas sensor devices were tested for responses towards CH₄, H₂, LPG, and CO₂ gases at 20 ppm concentrations of each. GO-SnO₂ nanocomposite sensing device showed optimal detection response towards the respective analyte gases with values of 5.00, 5.08, 4.90 and 3.41 respectively. The prepared nanocomposite showed stability and selectivity towards the target gases in an order of magnitude of H₂ > CH₄ > LPG > CO₂. The optimal gas sensor device’s dynamic gas sensing response was ascribed to the GO doping effect which relatively increased its surface area (46.48 m²g^-1) and absorption sites.

Abstract: Polyethylene glycol (PEG) coatings are developed for magnetite nanoparticles (NPs). The magnetic properties of superparamagnetic type, magnetite Fe₃O₄ nanoparticles are suitable for biosensing applications. Magnetic NPs were prepared by Co-precipitation method and oven dried. Using a Transmission Electron Microscope (TEM) and X-Ray Diffractometer (XRD), nanoparticles size and composition were found, including the presence of Fe₃O₄ peak. The magnetic properties are influenced by electron environments of the Fe³⁺ ions within the iron oxide structure. The magnetic properties were measured by Vibrating Sample Magnetometer (VSM), thus, the results of Fe₃O₄ NPs exhibited a high magnetic saturation (Ms) of 61.31 emu/g. In the case of PEG coated MNPs, confirmed by Fourier Transform Infrared Spectroscopy (FT-IR), a reduced Ms of 40.00 emu/g, which decreased further following surface modification with 3-aminopropyl triethoxysilane (NH₂) to 36.77 emu/g. The resulting size range of NPs of pure Fe₃O₄ NPs was 5-50 nm. In comparison, the PEG coated NPs were larger, 10-100 nm. In the part of protein binding and separation from solutions of bovine serum albumin (BSA) where investigated. This process will be beneficial to developing low cost sensors for biomolecules and biotechnologies in the future.

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: Nanosilica is a nanotechnology product with many substantial functions in many industries. Previous research showed that nano silica can be synthesized from geothermal silica, that caused silica scaling in injection well and turbine in geothermal power plant, reducing its power plant capacity by 40%. This research used geothermal silica as a precursor for nanosilica production with co-precipitation to recover amorphous silica from silica geothermal to reduce scaling while also increasing its economic value. The objectives of this study were to determine the model to represent the co-precipitation method for nano-silica by using nucleation and growth modelling, therefore help the scale-up process of nanosilica production. The experiment was conducted in four steps. (1) Silica washing utilized distillate water with a ratio of water to silica of 10:1 and sulfuric acid of 20% with a ratio of acid to silica of 4:1, both as a washing agent. (2) Preparation of HCl with concentrations of 3% and 9%. (3) Preparation of sodium silicate solution by reacting washed silica and NaOH to obtain sodium silicate. (4) Preparation of primary and secondary sodium silicate by diluting sodium silicate by two and four times to obtain primary and secondary sodium silicate, respectively. (5) Precipitation of sodium silicate with HCl consists of two steps using primary and secondary sodium silicate. The result showed that the model fit concentration data, with Sum of Squared Error (SSE) 1.9297.10-4, mass transfer coefficient rate is 9.8.10-3 dm/min, and the average relative error is 3.5%.