Papers by Keyword: Chemical Synthesis

Abstract: This article presents, the systematic and successful preparation of cadmium substituted cobalt ferrite (Co_1-xCd_xFe₂O₄) nanoparticles via simple co-precipitation method. X-ray diffraction study confirmed the prepared ferrite nanoparticles were crystallized with a mono phase cubic spinel structure of Fd3m space group. The average crystallite size (D_xrd) was increased with Cd doping content, due to the replacement of Co²⁺ ions by Cd²⁺ ions. XRD pattern revealed the high intense peak corresponds to (311) lattice plane and confirmed the formation of cubic structure ferrite nanoparticles. Morphological study was done by using SEM images. The grain size found to be increased with Cd concentration and it reaches the highest of around 0.9μm for Co_0.52Cd_0.48Fe₂O₄ composition. Fourier Transform Infrared spectroscopy of prepared samples was recorded in the range of 1000-350 cm^-1, confirmed the spinel structure.

Abstract: Chemical engineering frequently uses "process intensification" to consciously combine various phenomena or procedures. By treating the molecules in such a system in a way that every single molecule experiences the same processing, the selectivity is raised, enhancing productivity. For mass transfer limited reactions, the enhancement of the transport rates & the specific interfacial area are the typical approaches. These enable the reduction of diffusion path length, reduce hold-up and improve the controlling on temperature control, even for highly exothermic reactions. Micro reactor technology (MRT) is a subset of process intensification that aims to reduce the size of equipment, energy consumption, and waste generation. The research of peracetic acid (PAA) and perform acid (PFA) preparation is the focus of the current investigation. Amberlite IR-120H catalyst was used to study the synthesis of PAA and PFA in batch and micro-structured reactors while ultrasonic irradiations were present.. The current research describes a method for synthesizing both compounds in a batch and micro-structured reactors, with and without ultrasonic irradiation. Such a technology might be crucial in the online synthesis of these chemicals as it eliminates the need for harmful components to be transported and stored, assuring safety among other benefits. For these substances, various safety characteristics could be improved.

Abstract: This study aimed to investigate the effect of pH value raging from pH 4 - 8 on color development of silver colloids. Silver colloids with different colors were synthesized by chemical reduction method using NaBH₄ as a reducing agent and then adjusted pH value by adding dropwise of acetic acid. These silver colloids were characterized by Transmission Electron Microscopy and UV-Vis spectrophotometer. The results showed that the colors of silver colloids ranging from blue to yellow depended on amount of NaBH₄ added. Due to Localized Surface Plasmon Resonance (LSPR) properties, different shapes and sizes of silver nanoparticles resulting in different colors. It was found that the pH value also affected color development of silver colloids. By adjusting the pH value, the colors of silver colloids changed to different colors or shades, which were clarified by the changes in the center as well as intensity of the absorption spectra. Moreover, the silver colloid in an acidic condition led to aggregation of nanoparticles.

Abstract: Silver inorganic antibacterial agents have been widely used inbiotechnology, bioengineering science, electronics, optics and water treatment because of their strong bactericidal ability, high safety and durable antibacterial properties. In this paper, the preparation methods of silver nanoparticles are reviewed, including physical method, chemical method and biological method, in order to provide a reference for the further development and utilization of silver nano-antibacterial materials.

Abstract: Tb (AUFA)₃2H₂O, a rare earth terbium complex,was synthesized by introducing 4-(11-azobenzene-undecyloxy) ferrocene acid (AUFA) as the ligand. This complex was characterized by elemental analysis, MS, IR, Raman, UV spectroscopy and fluorescence spectrophotometry. The complex exhibited ligand-sensitized green emission, and Tb (AUFA)₃2H₂O had a higher sensitized luminescence efficiency and a longer lifetime than the other terbium complexes (DPC: 2, 6-Pyridinedicarboxylic acid, Aspirin: 2-ethanoylhydroxybenzoic acid). The organic-inorganic thin film of complexe Tb (AUFA)₃2H₂O in nanoTiO₂ was fabricated, and the nanoTiO₂ has been used in the luminescence layer to change the luminescence property of complexes Tb (AUFA)₃2H₂O. It was found that there was an efficient energy transfer process between the ligands and metal ions. Moreover, In an ITO/PVK/Tb (AUFA)₃2H₂O/Al device, Tb³⁺ may be excited by intramolecular energy transfer from the ligand, as observed by electroluminescence. The main emitting peak at 545 nm can be attributed to the ⁵D₄→⁷F₅ transition of the Tb³⁺ ion, and this process results in the enhancement of the green emission from the electroluminescence device.

Abstract: Monodisperse nickel phosphide (Ni₅P₄) nanoparticles supported on carbon (Ni₅P₄@C) were in situ synthesized by one step solution-phase route, in which the mixture of trioctyloxide (TOPO) and trioctylphosphine (TOP) was used as solvent, capping agent and phosphor source. Ni₅P₄nanocrystals were in situ coupled by active carbon simply adding the carbon to the reaction solution. The as-prepared Pt-free Ni₅P₄ nanocrystals exhibit the enhanced electrocatalytic activity toward hydrogen oxidation reaction (HOR) compared to pure commercial Ni nanoparticles. Therefore, the obtained Ni₅P₄@C nanocatalyst appears to be promising non precious metal electrocatalysts for HOR.

Abstract: Size-controlled silver nanoparticles are prepared at two different heating time duration (30 and 60min) under conventional heating at 80 ̊C in an aqueous solution of silver nitrate (AgNO₃) as a precursor and trisodium citrate (C₆H₅O₇Na₃^.2H₂O) as a reducing agent under continuous stirring. The size and size distribution of the resulting silver nanoparticles prepared under conventional heating are strongly dependent on the duration of heating. As the heating duration is increased, aggregation and grain growth is observed. When duration of heating was 60min a distinct increase in the particles size was observed that lead to shift in the plasmon band as confirmed by UV-Vis absorption spectroscopy. TEM images shows that silver nanoparticles are nearly spherical in shape and their sizes are ranging between 2-42 nm and their cubic structure was confirmed by X-ray diffractogram. From X-ray diffractogram we calculated crystallite size using Scherrer’s equation which comes out to about 36nm and that determined from Hall-Williamson plot turns out to be 19nm.

Abstract: δ-FeOOH nanosheets have been synthesized on a large-scale by a simple method using NH₃·H₂O as precipitant at pH 10. The samples were characterized by FESEM, XRD, TEM, FTIR and PPMS. The results of this characterization reveal that the complexes [Fe^III(OH)_n(NH₃)_m]³⁻ⁿ formed between Fe³⁺ ions and NH₃ favor nucleation and oriented growth of δ-FeOOH nanosheets. The influences of precipitant, the initial pH, and concentration of H₂O₂ on the structure and morphology of the as-prepared δ-FeOOH have been investigated. Magnetic investigations show that the δ-FeOOH nanosheets exhibit high coercivity.

Abstract: Water dispersed PdTe semiconducting nanocrystals were synthesized and stabilised with 3-mercaptopropionic acid (3-MPA). HRTEM studies revealed the formation of spherical nanoparticles of average size ~4 nm with good crystallinity. UV-visible spectral analysis and band gap measurements confirmed that the nanocrystals are indeed semiconductors. This semiconducting characteristic was supported by electrochemical impedance spectroscopy (EIS) data which gave Bode plots with absolute frequency and a maximum frequency phase angle values of 38.3° and 75°, respectively. Electroanalysis of the film on glassy carbon electrode (GCE) verified the retention of the ability of Pd to adsorb hydrogen on its surface as well as absorb hydrogen within its lattice.

Abstract: During the synthesis of γ-Fe₂O₃ nanoparticles by a chemically-induced transition method in FeCl₂ solution, Cu modification was attempted by adding CuCl/NaOH or CuCl₂/NaOH to the solution. The as-prepared products were characterized using VSM, TEM, EDS, XRD, and XPS. When adding a NaOH solution with a certain concentration, the components of the as-prepared products changed in relation to the copper salt used. When CuCl 2.5 × 10^-3 M was used, γ-Fe₂O₃/CuFeO₂ composite nanoparticles coated by FeCl₃·6H₂O and with an average size of 11.47 nm were formed. When the CuCl concentration increased to 5 × 10^-2 M, a mixture of γ-Fe₂O₃/CuFeO₂ and Cu (OH)Cl nanoparticles was formed. When 5 × 10^-2 M CuCl₂ was used, the final product contained γ-Fe₂O₃ nanoparticles, coated with FeCl₃·6H₂O, and Cu (OH)Cl nanoparticles. The magnetization of the as-prepared products depends on the content of the γ-Fe₂O₃ and CuFeO₂ ferrites.