The Temperature Effect on Magnetic Properties of NiFe2O4 Nanoparticles

TiFe2O4@SiO2-SO3H: A novel and effective catalyst for esterification reaction

In the present study, TiFe2O4@SiO2-SO3H heterogeneous catalyst was successfully synthesized and applied to generate biodiesel from oleic acid, and palmitic acid using an esterification process. In this sense, the nanocatalyst surface was characterized using TEM, TGA, XRD, FTIR, VSM, BET, SEM, and EDX analyses. Nanocatalyst TiFe2O4@SiO2-SO3H showed high activity for the esterification of oleic acid and palmitic acid. Also, the nanocatalyst can be easily recovered with a bar magnet and reused many times without any loss of activity.

Influence of SiO2 Embedding on the Structure, Morphology, Thermal, and Magnetic Properties of Co0.4Zn0.4Ni0.2Fe2O4 Particles

(Co_0.4Zn_0.4Ni_0.2Fe₂O₄)_α(SiO₂)_(100-α) samples obtained by embedding Co_0.4Zn_0.4Ni_0.2Fe₂O₄ nanoparticles in SiO₂ in various proportions were synthesized by sol-gel process and characterized using thermal analysis, Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, inductively coupled plasma optical emission spectrometry, and magnetic measurements. Poorly crystalline Co-Zn-Ni ferrite at low annealing temperatures (500 °C) and highly crystalline Co-Zn-Ni ferrite together with traces of crystalline Fe₂SiO₄ (800 °C) and SiO₂ (tridymite and cristobalite) (1200 °C) were obtained. At 1200 °C, large spherical particles with size increasing with the ferrite content (36-120 nm) were obtained. Specific surface area increased with the SiO₂ content and decreased with the annealing temperature above 500 °C. Magnetic properties were enhanced with the increase in ferrite content and annealing temperature.

Fabrication of a Nickel Ferrite/Nanocellulose-Based Nanocomposite as an Active Sensing Material for the Detection of Chlorine Gas

Chlorine gas is extensively utilised in industries as both a disinfectant and for wastewater treatment. It has a pungent and irritating odour that is comparable with that of bleach and can cause serious health issues such as headaches and breathing difficulties. Hence, efficiently, and accurately monitoring chlorine gas is critical to ensure that no undesirable incidents occur. Due to its remarkable characteristics, numerous researchers have explored the potential of ferrite nanoparticles as a sensing material for chlorine gas detection. Among several ferrite nanoparticles, nickel ferrite (NiFe₂O₄) is extensively studied as an inverse spinel structured magnetic material that may be ideal for sensing applications. However, the magnetic characteristics of NiFe₂O₄ cause agglomeration, which necessitates the use of a substrate for stabilisation. Therefore, nanocellulose (NC), as a green and eco-friendly substrate, is ideal for stabilising bare nickel ferrite nanoparticles. In a novel experiment, nickel ferrite was loaded onto NC as a substrate using in situ deposition. The structure was confirmed by X-ray Diffraction (XRD) analysis, while elemental composition was verified by Energy dispersive X-ray (EDX) analysis. Gas sensing properties were determined by evaluating sensitivity as a function of various regulating factors, such as the amount of nickel ferrite, gas concentration, repeatability, and reusability. In the evaluation, 0.3 g nickel ferrite showed superior response and sensitivity than those of other samples. The achieved response time was around 40 s, while recovery time was about 50 s. This study demonstrates the potential of a nickel ferrite/nanocellulose-based nanocomposite to efficiently monitor chlorine gas.

Effect of Ce3+ Ions Doped NiFe₂O₄ Magnetic Nanoparticles on Photocatalytic Degradation of Rhodamine B and Antibacterial Activities

In this study, spinel NiCe_xFe_2-XO₄ (x = 0.0 - 0.5) nanoparticles (NPs) was synthesized by microwave combustion technique (MCT) utilizing the fuel of Aloe vera plant extract. The establishment of spinel cubic crystal structure was ensured by powder X-ray diffraction (PXRD) technique. The particles like nanostructured morphology were confirmed by high-resolution scanning electron microscope (HRSEM). Energy dispersive X-ray (EDX) studies confirmed the formation of spinel ferrite structure and ensured that no other elements were present. Magnetic parameters such as remanant magnetisation (Mr), coercivity (He) and saturation magnetization (Ms) were calculated from the magnetic hysteresis (M-H) loops, which exhibited ferromagnetic behaviour. The photocatalytic behavior was investigated by visible light treatment for the photocatalytic degradation (PCD) of rhodamine B (Rh-B) dye and the sample NiCe_0.3Fe_1.7O₄ exhibits higher PCD efficiency (93.88%) than other compositions. The antibacterial activities of gram-positive S. aureus, B. subtilis, gramnegative K. pneumonia and E. coli have been investigated using undoped and Ce³⁺ substituted NiFe₂O₄ NPs and observed higher activity, which indicated that, they can be used in the bio-medical applications.

State-of-art of silver and gold nanoparticles synthesis routes, characterization and applications: a review

To date, the noble metal-based nanoparticles have been used in every field of life. The Au and Ag nanoparticles (NPs) have been fabricated employing different techniques to tune the properties. In this study, the methodologies developed and adopted for the fabrication of Au and Ag have been discussed, which include physical, chemical and biological routes. The Au and Ag characteristics (morphology, size, shape) along with advantages and disadvantages are discussed. The Au and Ag NPs catalytic and biomedical applications are discussed. For the Ag and Au NPs characterization, SEM (scanning electron microscope), TEM (transmission electron microscope), FTIR (Fourier transform infra-red spectroscopy), XRD (X-rays diffraction) and DLS (dynamic light scattering) techniques are employed. The properties of Au and Ag NPs found dependent to synthesis approach, i.e., the size, shape and morphologies, which showed a promising Catalytic, drug delivery and antimicrobial agent applications. The review is a comprehensive study for the comparison of Au and Ag NPs synthesis, properties and applications in different fields.

An effective strategy for the development of multiferroic composite nanostructures with enhanced magnetoelectric coupling performance: a perovskite-spinel approach

An energy efficient move toward the regulation of magnetization vector solely with E-field by developing multiferroic (MF) magnetoelectric (ME) nanostructures' have opened up vast avenues for novel low power consumption memories and magnetoelectric devices. The present study delineates the development of multiferroic nanocomposites (MF NCs) with perovskite BiFeO₃ and spinel NiFe₂O₄. A simple Pechini one-pot method is employed for the preparation of nanocomposites with different molar concentrations and the modified structural, magnetic, dielectric, and magnetoelectric performance of NCs is carried out at room temperature. The purity in the crystalline phase of BiFeO₃ and NiFe₂O₄ in the NCs are corroborated by XRD and FTIR spectroscopy, which is further substantiated, while EDAX analysis pointed out the elemental composition. The SEM images provide an evidence for the closely compacted and agglomerated grains with some voids in the prepared sample. A well saturated magnetic hysteresis (M-H) loop reveals long range ferromagnetic ordering and the remanence value ascertains the multidomain structure. The dielectric performance and impedance analysis imparts greater knowledge of the dependence of grain and grain boundaries on the resistive and conductive behavior of the composites. The frequency dependence of electric modulus and impedance exhibits a non-Debye type of relaxation process. The P-E hysteresis loops clearly show the lossy behavior of the composites with an increase in the NiFe₂O₄ concentration. The ME coupling coefficient of the composites evaluated using the dynamic magnetic field method demonstrates the effective coupling interaction between ferroelectric (FE) perovskite BiFeO₃ and ferromagnetic (FM) spinel NiFe₂O₄. Thus, the findings disclose a greater potential for innovative applications in spintronics and information technology.

Kinetic and thermodynamic studies for evaluation of adsorption capacity of fungal dead biomass for direct dye

This study focuses on evaluation of degradation aptitude of white rot fungus (Coriolus versicolor) against Indosol Turquoise FBL dye. The outcome of numerous parameters including pH, temperature, carbon sources, nitrogen sources, C/N ratio and effect of dye concentration were studied. Maximum decolorization (99.896%) of Indosol Turquoise FBL was obtained by C. versicolor under optimized conditions. After three days, the maximum dye degradation (98%) was observed at pH 4 and 30 °C. Six carbon sources fructose, glucose, maltose, sucrose, rice bran and wheat bran were used and 96.66% degradation was observed by maltose at its optimum growth concentration (0.1 g/100 mL). Various nitrogen sources were employed for decolorization but ammonium nitrate decolorized dye up to 98.05%. The activity of three different enzymes laccase, Lignin peroxidase (LiP) and Manganese peroxidase (MnP) were calculated. The dead biomass of White rot fungus (WRF) was used for biosorption experiments. Maximum q (36 mg/g) was obtained at pH 2, at 30 °C using 0.05 g biosorbent. An increase in the q value was observed with increase in dye concentration. Freundlich adsorption isotherm and pseudo second order kinetics were followed by the data. It can be concluded that C. versicolor could be an efficient source for degradation of dyes from industrial effluents.

A Novel Approach for Fabricating LaMnO3 Thin Films Using Combined Microwave Combustion and Pulsed Electron Deposition Techniques

LaMnO3 (LMO) nanopowder was synthesized by the microwave combustion method using glycine and nitrate salts of La and Mn as precursors. The as-prepared LMO powder was pressed at high pressure and annealed at 1000°C for 8 hours to make a target for thin film deposition. The structural and elemental analysis was obtained by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Thin films of LMO were fabricated using pulsed electron deposition (PED) at room temperature. The effects of discharge voltage and oxygen/argon flux ratio on the produced thin films were studied. The study shows that stoichiometry and structure of the target was preserved well in the thin films prepared with a discharge voltage from 14 to 15 kV, while the oxygen/nitrogen flux ratio did not show a clear effect on the quality of thin films.