Chemical Co-precipitation Method Research Articles

Structural, magnetic, optical, and antibacterial properties of Mn1-xNixFe2O4 nanoparticles

Herein, we report the synthesis of Mn1-xNixFe2O4 (MNFO) nanoparticles (NPs) with lime peel and capsicum coating for different compositions (x = 0.0–0.4) by chemical co-precipitation method tested for antibacterial properties. The coated sample, Mn0.6Ni0.4Fe2O4 NPs has exhibited excellent antibacterial activity against gram positive and negative species compared to uncoated ones. Significantly, lime peel coated samples have exhibited more antibacterial effect as compared to capsaicin coated at x = 0.4. The crystallite size of the sample analysed via X-ray diffraction (XRD) is in nano regime, 7–10 nm. Results show considerably low strain for all samples except a peak value for composition at x = 0.1; which can be ascribed to the cation distribution and different ionic radii of the bivalent metal ions. Fourier transform infrared spectroscopy (FTIR) confirms presence of functional groups. The ultraviolet visible (UV–Vis) spectra reveal indirect band gap of 2–2.5 eV. The field emission scanning electron microscopy (FESEM) analysis shows nano cubical structure. The energy dispersive x-ray (EDX) spectroscopy confirms the presence of elements (Mn, Ni, Fe, and O) in the sample. The magnetic properties have investigated using vibrating sample magnetometer (VSM), shows saturation magnetization and remnant magnetization decreases with increasing Ni content. The low values of saturation magnetization and coercive force is indicative of formation of soft ferrite with super paramagnetic in nature.

Enhancing structural and magnetic properties of BaFe12O19 nanoparticles through co-substitution (Co-Mn): A promising approach for permanent magnet applications

In-depth study into the creation and improvement of rare-earth free permanent magnets, particularly ferrites, has been sparked by recent economic and environmental concerns. M-type barium hexaferrites (BaFe12O19, pure BHF) are a class of low-cost permanent magnets with an excellent curie temperature and good resistance to oxidation and corrosion that are significant from a technological perspective. In the current study, the experimental conditions are optimized to obtain barium hexaferrite (BaFe12O19) co-substituted with transition elements (Co and Mn) (BaFe12–2xCoxMnxO19) via the chemical co-precipitation method. In this framework, different substitution possibilities will be investigated. The structure, morphology, vibrational spectrum, and thermal stability of the generated nanoparticles were revealed using powder x-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Rietveld refinement was used to estimate the average bond length and bond angle in order to determine the impact of superexchange interaction. Based on more precise structural characteristics, the atomic occupation and distribution of bonds are depicted from their charge density graph. For all the synthesized materials, the maximum energy product (BH)max and magnetic characteristics (VSM) were also investigated. The potential causes of this phenomenon were examined and discussed at length.

Gallium substitution influence on microstructure and magnetic properties of Y-type Ba0.5Sr1.5Zn2Fe12O22 hexaferrites

Y-type hexagonal ferrites of Ba0.5Sr1.5Zn2Fe(12-x)GaxO22 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) are synthesized by chemical co-precipitation method. X-ray diffraction (XRD) analysis reveals that the samples are single-phase and the space group is R3¯m. The field-emission scanning electronic microscope (FE-SEM) results indicate that the grains are regular fibrous shape with a width of about 2–5 µm and a thickness of 1–3 µm. In the M-T diagram, it can be observed that the temperature at which the transition from helical to ferrimagnetic (TS) increases first and then decreases with increasing substitution amount x. From σ-H, the values of coercive field (HC) experience alternating decreases and increases, and reaches a maximum value of 567.34 Oe at x = 0.8. While the specific saturation magnetization (σS) values exhibit a monotonic decrease with the increasing x. The variations in magnetic properties can tentatively be ascribed to the effect of Ga3+ substitution. These results above might be used as promising candidates in electric devices.

Preparation and characterization of La-doped Y3Al5O12 as a potential protective coating material against CMAS corrosion

Mitigating calcium‑magnesium‑aluminum-silicate (CMAS) corrosion attack on thermal barrier coatings (TBCs) has attracted increasing interest. In this study, (Y1-xLax)3Al5O12 (x = 0, 0.1, 0.2, 0.3) were synthesized by the chemical co-precipitation method. The La-doped Y3Al5O12 was composed of Y3Al5O12 and LaAlO3 phases. As the La3+ doping concentration increased, the content of the LaAlO3 phase gradually increased. Compared to un-doped Y3Al5O12, the fracture toughness and Vickers hardness of Y3Al5O12 doped with 20 mol% La3+ increased by 54.9 % and 72.5 % respectively, reaching 2.88 MPa·m1/2 and 18.03 GPa. The thermal expansion coefficient of Y3Al5O12 doped with 30 mol% La3+ reached 9.79 × 10−6/K at 1000 °C, which was 7. 34 % higher than that of the un-doped Y3Al5O12. The CMAS corrosion resistance of (Y1-xLax)3Al5O12 gradually improved with the increase of LaAlO3 content. LaAlO3 promoted the formation of a dense apatite-spinel reaction layer and effectively inhibited the penetration of CMAS. (Y1-xLax)3Al5O12 (x = 0.1, 0.2, 0.3) can act as a potential protective coating material against CMAS corrosion.

Excitation-wavelength-dependent photoluminescence/electrical conductivity of copper oxide nanorods

This research work reports the synthesis of copper (II) oxide (CuO) nanoparticles using the wet chemical co-precipitation method. The synthesised nanoparticles were characterised using ultraviolet–visible spectroscopy, X-ray diffraction, field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy in terms of absorption, crystal structure and size, morphology and elemental composition, and particle size. The existence of functional groups was verified by Fourier transform infrared spectroscopy. The synthesised copper (II) oxide nanoparticles showed an absorption peak at 397 nm, and a Tauc’s plot study showed a band-gap energy of 3.2 eV. The effects of varied excitation energies – namely, 3.81 and 3.54 eV – on the emission spectra of rod-shaped nanoparticles were assessed through photoluminescence spectroscopy, and the release of red, orange, green, violet and yellow colours was observed. The voltage–current characteristics of nanoparticle pellets were measured using a two-probe technique. The increase in the direct-current electrical conductivity of pellets heated at 100 and 200°C was ascertained. Overall, this research work provides valuable insights into the electronic properties of copper (II) oxide nanoparticles, which could have potential applications in various fields such as catalysis and electronics.

Evaluation of Magnetic Hyperthermia Efficiency of PEG-Coated Fe3O4 Nanoparticles

Magnetic nanoparticle hyperthermia has drawn considerable interest in cancer therapy. In this study, we report the synthesis of PEG-coated Fe3O4 nanoparticles and evaluate their suitability for magnetic hyperthermia applications. Fe3O4 nanoparticles were synthesized by the chemical coprecipitation method, which are coated with polyethylene glycol (PEG). PEG-coated Fe3O4 nanoparticles were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), dynamic light scattering (DLS) and transmission electron microscopy (TEM). Synthesized nanoparticles possess inverse-spinel structural with a crystallite size of 9.1[Formula: see text]nm. From the M-H hysteresis loops, it was confirmed that the synthesized Fe3O4 nanoparticles were superparamagnetic. The physical size of bare Fe3O4 nanoparticles, as determined from the HR-TEM, is [Formula: see text][Formula: see text]nm, and the corresponding hydrodynamic size of PEG-coated Fe3O4 nanoparticles is [Formula: see text][Formula: see text]nm. Magnetic hyperthermia efficiency of PEG-coated Fe3O4 nanoparticles was determined as a function of magnetic field frequency (162–935.6[Formula: see text]kHz), field strength (5–12[Formula: see text]mT) and nanoparticle concentration (1–100[Formula: see text]mg/mL). Temperature rise in an aqueous dispersion of PEG-coated Fe3O4 nanoparticles was measured for 20[Formula: see text]min. The specific loss power (SLP) was calculated by the corrected slope method. SLP values of PEG-coated Fe3O4 nanoparticles increase with magnetic field frequency and field strength and decrease with nanoparticle concentration. The optimum hyperthermia performance of PEG-coated Fe3O4 nanoparticles was observed for 935.6[Formula: see text]kHz frequency, 10[Formula: see text]mT field strength and 25[Formula: see text]mg/mL concentration. Under these conditions, the measured SLP of PEG-coated Fe3O4 nanoparticles was 4.43[Formula: see text]W/g. These results show that the synthesized PEG-coated Fe3O4 nanoparticles could be a potential candidate for magnetic hyperthermia treatment of cancer.

Two-dimensional tungsten oxide nanoflakes grafted over g-C3N4 as excellent electrode materials for hybrid supercapacitors

This paper presents the successful design of nanocomposites comprising metal oxide modification over graphitic carbon nitride (g-C3N4) applicable as efficient electrode materials for hybrid supercapacitors. Two-dimensional tungsten oxide (WO3) nanoflakes were synthesized with an acid-assisted precipitation method followed by hydrothermal treatment. Nanocomposite WO3/g-C3N4 has been reported as specially designed electrode materials for supercapacitors where nano WO3 grafted over g-C3N4 nanosheets by in-situ chemical co-precipitation method. Various structural and electrochemical analyses were performed to investigate the overall morphological dependency of the charge storage phenomenon. The synthesized WO3/g-C3N4 nanocomposites exhibit superior specific capacitance of 1051.43 Fg−1 at 1 Ag−1, having a capacity retaining of 85.1 % performed at 10 Ag−1 after 10,000 cycles. However, the fabricated asymmetric supercapacitor has achieved an energy density of 114.75 Whkg−1 at 8.5 kWkg−1 power density. The combination enhancement of energy density with notable cycle stability of WO3/g-C3N4 than WO3 and g-C3N4 nanosheets are accredited to the excellent structural, thermal, and electrochemical stability possessed by the heterostructure WO3/g-C3N4 and thus proposing a promising electrode material for hybrid supercapacitors.

Enhanced electrochemical performance of CuO/NiO/rGO for oxygen evolution reaction

To design the highly active, stable electrocatalyst for oxygen evolution is emerging as challenging task for sustainable energy production. Herein, we fabricated the non-noble CuO/NiO/rGO nanocomposite approached by facile chemical co-precipitation method. The successful formation of binary metal oxide nanocomposite with reduced graphene oxide was confirmed with monoclinic CuO and cubic NiO, which is clearly revealed in the XRD diffraction results. By incorporating the CuO and NiO into the rGO sheets results homogeneous tiny nanoparticles morphology decorated on the graphene sheets which improving interaction among metal nanoparticles and carbon based products. The electrocatalytic performance of resultant binary metal oxide nanocomposite with rGO was investigated in alkaline KOH environment towards oxygen evolution reaction. The 200 mV overpotential was attained at 10 mA/cm2 with smaller 165 mV/dec Tafel value. The elevated electrochemical surface area (ECSA) value of 132.5 cm2 was estimated from cyclic voltammetry analysis of optimized CuO/NiO/rGO electrocatalyst. The electrochemical impedance spectrum of the prepared electrocatalyst shows that the low 0.04 Ω charge transfer resistance is highly desirable to the better conductivity. The prepared CuO/NiO/rGO electrocatalyst stability was verified by chronoamperometry test at low 10 mA/cm2 and exhibited stable performance up to 16 h towards OER. Hence, this work contributes innovative synergistic approach for growth of cost effective binary metal-oxide (CuO/NiO) nanocomposite combined with conductive carbon material for oxygen evolution reaction.

Prussian blue analogues with tunable electron structure by different transition metal salts for wide spectrum photocatalytic hydrogen evolution

Photocatalytic hydrogen evolution is regarded as an efficient approach to fulfill future energy requirements. Prussian blue analogues (PBAs) serving as distinctive Metal-organic frameworks, feature a multi-electron, multi-core structure, as well as exceptional properties like structural stability and compositional adjustability. These attributes endow them with significant promise in the realm of photocatalytic hydrogen evolution. In this work, the six kinds of common transition metal salts were employed in synthesizing Prussian blue analogues (Cd–Co PBAs, Cu–Co PBAs, Co–Co PBAs, Ni–Co PBAs, Zn–Co PBAs and In–Co PBAs) featuring varying metal compositions through the chemical co-precipitation method. A comprehensive analysis was subsequently carried out to explore the connection between their structural features and properties. The six kinds of Prussian blue analogues were directly used as catalysts to evaluate their performance in photocatalytic hydrogen evolution, accompanied by a thorough investigation into the impact of their structural variations on their ability to facilitate photocatalytic hydrogen evolution. Among them, Ni–Co PBAs has the highest photocatalytic hydrogen evolution rate (6197.4 μmol h−1 g−1) and the highest apparent quantum efficiency (AQE) of 5.75 % at 475 nm due to the suitable band gap structure and the ideal MII/MIII atomic ratio (3:2). When explaining the correlation between electronic structure and properties of PBAs, the density functional theory (DFT) calculation gives further insight. This work provides a comprehensive understanding of the structure and properties of PBAs, which will provide a sustainable strategy for the development of photocatalysts based on PBAs for achieving high conversion efficiency of solar energy into hydrogen energy.

A comparative study of structural properties of oleic acid coated metal nanoparticles (Co, Ni, Fe) by co-precipitation method

Metal nanoparticles of cobalt, nickel and iron were synthesized by chemical co-precipitation method using Sodium Borohydride as the reducing agent. The metallic particles were coated with oleic acid to prevent the formation of oxides on the surface layers. The structural analysis of both coated and uncoated samples were carried out using XRD technique and FTIR spectroscopy. XRD patterns of the uncoated samples showed the significant presence of oxide phases of the metallic nanoparticles while in the case of coated samples, the metallic phase was observed. A significant observation from the XRD patterns of the coated samples was the presence of a broad peak centred at 20–210 which is indicative of the graphitic structures typically observed as (002) reflections of graphite. However, the broadened peak depicted the formation of layered graphitic structures of Graphene/ nano tubes/fullerene/ nano onions. The stretching vibration of C = O and symmetric stretching vibrations of the –COO–functional group in the FTIR spectrum, indicated that the layer of oleic acid was successfully coated on the surface of MNPs. The graphitic structures of all oleic acid coated metal nanoparticles were confirmed by Raman spectroscopy. The formation of graphitic structure was the result of the catalytic action of metal nanoparticles..

Mn4+-doped organometallic hafnium hexafluoride phosphors: Achieving near-unity quantum yield to elevate LED performance

Mn4+-activated fluoride phosphors with high luminous efficacy and short decay lifetimes are essential in realizing high-quality warm white-light-emitting diode (WLED) lighting. In this work, Mn4+-activated narrow-band red (∼630 nm) phosphor [(CH3)4N]2HfF6 was successfully synthesized by introducing an organic cationic group (tetramethylammonium) into the [HfF6]2- system using a mild chemical co-precipitation method. The sample structure was confirmed using various characterization techniques such as scanning electron microscopy, X-ray diffraction and Raman spectroscopy. Powder particles with diameters ranging from 10 to 20 um and double pyramidal structures were prepared by adjusting the anti-solvent temperature to control the crystal growth rate. The investigation of the morphology, structure and photoluminescence properties of Mn4+-doped [(CH3)4N]2HfF6 phosphors at different anti-solvent temperatures deepened our understanding of the correlation between structure and luminescence. Ultimately, phosphors with optimal performance (external quantum efficiency, ∼92.2%, and decay lifetime, ∼3.6 ms) were obtained. The samples were mixed with polydimethylsiloxane organosilicon to prepare a red light-conversion flexible film, and the (TMA)2HfF6:Mn4+ red phosphor and commercially available YAG:Ce3+ yellow-green phosphor was thoroughly mixed with transparent silica to form a stable paste, and then coated on a blue LED bead to prepare warm white LEDs, which significantly optimized the performance of the white LEDs (correlated color temperature, ∼5564 K). These experimental results indicate that the materials prepared by the mild solution method have important applications in the domains of display and lighting.

Cu doped ZnO nanoparticles: Correlations between tuneable optoelectronic, antioxidant and photocatalytic activities

Microstructural, optical and electronic properties of Cu doped ZnO nanoparticles with a general formula Zn1-xCuxO (x = 0.0, 0.1 and 0.2) prepared via wet chemical co-precipitation method were investigated thoroughly. Both the free radicals scavenging properties and photocatalytic activities of synthesized nanoparticles were explored. Formation of pure hexagonal wurtzite crystal structure of entire samples were identified by recorded x-ray diffraction patterns. For determining both the mean crystallite size and intrinsic microstrain of all the samples, several standard methods were utilized and a comparative study was introduced. Average size, morphology and shape regularity of synthesized samples were examined using HRTEM images. Optical direct band gap estimated from Tauc plots was noted to reduce with increasing Cu concentration in ZnO nanoparticles. Collected FTIR spectra at 300 K also validated the incorporation of Cu ions and their complete dissolution in the host ZnO crystal structure. It is also found that the hopping of electrons is the fundamental charge conduction process for all the samples in presence of ac electric field. FDTD simulation clearly predicts increase in electric field intensity with increased doping of Cu. There could be a plasmonic coupling between particles at the hotspot region that increases the electric field intensities. BET study revealed that the 10 % Cu doped ZnO sample has highest specific surface area which implies it contains more active sites for taking part in rapid photodegradation of toxic dyes compared to other samples. It was observed that the 10 % Cu doped ZnO nanoparticles were more efficient in degrading toxic dyes and the degradation pathway of all the samples obeyed first order rate kinetics model. Based on estimated bandgap of nanoparticles, a possible mechanism for the Rhodamine B (RhB) and Methylene blue (MB) dye degradation is suggested. All the prepared samples also exhibited notable antioxidant properties. Consequently, this study clearly shows that the Cu doped ZnO nanoparticles are the effective nanomaterial for photocatalytic and antioxidant applications.

Centrifugally spun magnetic nanofibers for anionic dye removal: Optimization and predictive modeling with RSM and ANN

Response surface methodology (RSM) and artificial neural network (ANN) approach were used for the modeling-optimization of dye removal by adsorption using poly(ethylene terephthalate)/Fe3O4 nanocomposites nanofibers. The nanoparticles of Fe3O4 were synthesized by the chemical co-precipitation method in the presence of linoleic acid as a stabilizer. The polymer matrix was obtained by recycling PET from plastic water bottles. We used a simple homemade centrifugal spinning device to prepare PET/Fe3O4 nanofibers and the resulting material was characterized by XRD, FTIR and SEM. The performance of the nanofiber material as an adsorbent was examined in water treatment to remove Naphthol Green B anionic dye in batch mode. Box–Behnken-RSM and ANN were employed to optimize the effect of pH, contact time, initial dye concentration, and adsorbent mass. The optimized conditions leading to the maximum predicted dye removal were a pH of 2, a contact time of 60 min, an adsorbent mass of 0.125 g/L, and a dye concentration of 20 mg/L, and. The results demonstrated that both methods showed good predictions of dye removal. The pseudo-first-order kinetic and Langmuir isotherm models were found to be best fitted with the experimental data and rePET/Fe3O4 exhibited a maximum NGB dye adsorption capacity up to 155 mg/g. This study also indicates that magnetite nanoparticles combined with recycled PET in the form of nanocomposite nanofibers could be used for the treatment of dye wastewater.

Comparative upconversion emission studies in AF3: Tm3+/Yb3+ (A=La, Y and Gd) phosphor for latent fingermarks detection

In this work the effect of change of host lattice on upconversion emission properties of Tm3+/Yb3+ doped/codoped fluoride upconversion phosphor particle with host variations is discussed. Lanthanum (La), yttrium (Y) and gadolinium (Gd) based fluoride hosts are selected and Tm3+/Yb3+ ions combination is incorporated via chemical co-precipitation method. The structural and optical properties of developed systems is studied through FE-SEM, XRD, FTIR, Thermogravimetric analysis and visible upconversion emission. Further, these samples were utilised for latent fingermarks detection on different difficult surfaces. Results obtained are appreciable for security and forensic detection purposes.

A novel magnetic NiFe2O4-Ag-ZnO hybrid nanocomposite for the escalated photocatalytic dye degradation and antibacterial activities

The eco-friendly and cost-effective NiFe2O4-Ag-ZnO (nickel ferrite-silver-zinc oxide) (NFAZnO) nanocomposite was made using an easy straightforward chemical co-precipitation method and subsequent thermal treatment process. The increased UV light-driven photocatalytic performance and enhanced antibacterial activity of the nanocomposite were reported. The structural, morphological, magnetic, and catalytic characteristics of the nanocomposite were characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), photoluminescence (PL), Raman, vibrating-sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analysis. The results from XRD revealed that NFAZnO has a crystalline structure and EDAX elemental mapping confirmed the uniform distributed of all the elements in the matrix. Investigations into the microstructure found ultrafine grained structure of NFAZnO nanocomposite with an average crystallite size of 27.95 ± 0.38 nm as calculated from Scherrer’s formula. NFAZnO nanocomposite has a specific surface area of 13.56 m2/g, which is significantly more than ZnO (6.89 m2/g) as calculated from BET. At normal temperature, the magnetic characteristics showed the superparamagnetic behavior of the nanocomposite with saturation magnetization (Ms) value of 6.59 emu/g, remnant magnetization (Mr) value of 0.75 emu/g, and coercive field (Hc) value of 170 Oe. The Ag doping and addition of NiFe2O4 induces depletion in near-band edge emission, which lowers the rate of electron-hole recombination, according to the PL observations. Methylene Blue (MB) dye was subjected to photocatalytic degradation under the exposure to UV light, and according to the findings, NFAZnO nanocomposite exhibited the highest levels of photocatalytic activity with 98% degradation in just 60 min. The NFAZnO nanocomposite also showed enhanced antibacterial activity against Escherichia coli (E. coli) having zone of inhibition (ZOI) of about 28.9 ± 0.28 mm showing 123.5% activity as compared to control ampicillin having ZOI of 23.4 ± 0.13 mm, proving its applicability for both biomedical and environmental applications.

Study on the Preparation and Heat Transfer Characteristics of Temperature Sensitive Magnetic Fluid

Water-based temperature sensitive magnetic fluid and kerosene-based temperature sensitive magnetic fluid are prepared by using chemical co-precipitation method. The effects of magnetic particle concentration, magnetic field strength, and temperature on its thermal conductivity and viscosity were Studied. The results show that the thermal conductivity of the fluid is greatly increased by addition of magnetic particles. The thermal conductivity of water-based magnetic fluid with a concentration of 10% is increased 27.3% compared with that of deionized water; and the thermal conductivity of kerosene-based magnetic fluid with concentration of 10% is increased 128.8% higher than that of kerosene based-liquid. An experimental platform for the cooling loop is set up to verify the starting time and heat transfer characteristics of the developed magnetic fluid.

Cation substitution and size confinement effects on structure, magnetism and magnetic hyperthermia of BiFeO3-based multiferroic nanoparticles and hydrogels

Highly crystalline BiFeO3 (BFO), Bi0.97Sm0.03FeO3 and BiFe0.97Co0.03O3 nanoparticles are synthesized via the chemical co-precipitation method after calcination at 600 °C in air for 2 h. The effect of cation substitution, Sm for Bi and Co for Fe, on the structural and magnetic properties of BFO nanoparticles is investigated, whereas their magnetically induced heating efficiency in radio frequency alternating magnetic fields is examined. X-ray diffraction indicates the formation of the R3c phase in all compounds, while the corresponding Rietveld refinement reveals a variation of the lattice parameters upon doping, suggesting structural distortion within the BFO lattice due to the ionic radii mismatch between doped and host elements. Transmission electron microscopy unveils smaller particle sizes for the doped nanoparticles, owing to the frustrated particle growth induced by the dopants, whose presence is verified by X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. The combined effect of cation substitution and size confinement results in the suppression of the spiral spin structure of BFO, leading to the significantly enhanced magnetic features of the doped nanoparticles at room temperature. For possible applications in the biomedical sector, we tested them as heating agents in magnetic hyperthermia. The dispersion of BiFe0.97Co0.03O3 nanoparticles in water at a concentration of 4 mg/mL could reach the therapeutic window of 41–45 °C for cancer treatment in 50 mT at 375 kHz, whereas the remarkable temperature increase of the BFO-based multiferroic hydrogels, under the same conditions, is auspicious for an effective local treatment at reduced toxicity.

Surfactant-Capped Silver-Doped Calcium Oxide Nanocomposite: Efficient Sorbents for Rapid Lithium Uptake and Recovery from Aqueous Media

The demand for lithium is constantly increasing due to its wide range of uses in an excessive number of industrial applications. Typically, expensive lithium-based chemicals (LiOH, LiCl, LiNO3, etc.) have been used to fabricate adsorbents (i.e., lithium manganese oxide) for lithium ion (Li+) adsorption from aqueous sources. This type of lithium-based adsorbent does not seem to be very effective in recovering Li+ from water from an economic point of view. In this study, an innovative nanocomposite for Li+ adsorption was investigated for the first time, which eliminates the use of lithium-based chemicals for preparation. Here, calcium oxide nanoparticles (CaO-NPs), silver-doped CaO nanoparticles (Ag-CaO-NPs), and surfactant (polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS))-modified Ag-CaO (PVP@Ag-CaO and SDS@Ag-CaO) nanocomposites were designed by the chemical co-precipitation method. The PVP and SDS surfactants acted as stabilizing and capping agents to enhance the Li+ adsorption and recovery performance. The physicochemical properties of the designed samples (morphology, size, surface functionality, and crystallinity) were also investigated. Under optimized pH (10), contact time (8 h), and initial Li+ concentration (2 mg L−1), the highest Li+ adsorption efficiencies recorded by SDS@Ag-CaO and PVP@Ag-CaO were 3.28 mg/g and 2.99 mg/g, respectively. The nature of the Li+ adsorption process was examined by non-linear kinetic and isothermal studies, which revealed that the experimental data were best fit by the pseudo-first-order and Langmuir models. Furthermore, it was observed that the SDS@Ag-CaO nanocomposite exhibited the highest Li+ recovery potential (91%) compared to PVP@Ag-CaO (85%), Ag-CaO NPs (61%), and CaO NPs (43%), which demonstrates their regeneration potential. Therefore, this type of innovative adsorbents can provide new insights for the development of surfactant-capped nanocomposites for enhanced Li+ metal recovery from wastewater.

The mechanism and preparation of nano-SnO2@fly ash antistatic composite powder

In order to solve the problems of poor antistatic property of fly ash (FA), high cost and easy agglomeration of nano tin dioxide (TO), chemical co-precipitation method was adopted to synthesize nano-SnO2@fly ash (shell@core, TOFA) antistatic composite powder. Volume resistivity was used as indicator of TOFA antistatic performance to be experimentally studied. The results showed that volume resistivity was reduced from 7.32 × 109 Ω·cm (FA) to 1.82 × 105 Ω·cm (TOFA). Under pH = 4 condition, the electrostatic attraction between TO precursor and FA didn't significantly improve agglomeration. The pH = 12 condition of two substances surface repeled each other and relyed the interaction of TO precursor functional group and FA surface hydroxyl group on forming (Al)Si-O-Sn chemical bonding at high temperature calcination, which facilitated the formation of nanoscale tetragonal crystalline phase TO to uniformly distribute on the surface of micron-sized FA. The antistatic mechanism was derived from oxygen vacancies and tin interstitium in the intrinsic defects of TO nanoparticles.

Influence of Zinc Substitution on the Structural, Dielectric, and Gas-Sensing Properties of Mg1-xZnxFe2O4 Nanoparticles.

In the present work, Mg1-xZnxFe2O4 (MZFO) nanoparticles with x = 0.0, 0.2, 0.35, and 0.5 were synthesized via a chemical coprecipitation method. The study aimed to explore the effect of substituting Mg with Zn in MZFO on its structural, dielectric, and gas-sensing properties. The spinel phase formation was confirmed using X-ray diffraction, and the morphology of the prepared nanoparticles was revealed using scanning electron microscopy. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the band ranges of 500-600 cm-1 for tetrahedral and 390-450 cm-1 for octahedral lattice sites. The dielectric data showed that Zn substitution in MZFO decreased both the dielectric constant and loss with increasing frequencies and attained a stagnant value at higher frequencies. Furthermore, the gas-sensing characteristics of Zn-substituted spinel ferrites at room temperature for CO2, O2, and N2 were studied. The nanostructured MZFO exhibited high sensitivity in the order of CO2 > O2 ≫ N2 and showed a good response time of (∼1 min) for CO2, demonstrating that MZFO can be a good potential candidate for gas-sensing applications.