A review of methods for synthesis of nanostructured metals with emphasis on iron compounds

Synthesis of metal nanoparticles with specific properties is a newly established research area attracting a great deal of attention. Several methods have been put forward for synthesis of these materials, namely chemical vapor condensation, arc discharge, hydrogen plasma—metal reaction, and laser pyrolysis in the vapor phase, microemulsion, hydrothermal, sol-gel, sonochemical, and microbial processes taking place in the liquid phase, and ball milling carried out in the solid phase. The properties of metal nanoparticles depend largely on their synthesis procedures. In this paper the fundamentals, advantages, and disadvantages of each synthesis method are discussed.     

Surface Modification of Magnetic Nanoparticles Using Gum Arabic

Magnetite nanoparticles were synthesized and functionalized by coating the particle surfaces with gum arabic (GA) to improve particle stability in aqueous suspensions (i.e. biological media). Particle characterization was performed using transmission electron microscopy (TEM) and dynamic light scattering (DLS) to analyze the morphology and quantify the size distribution of the nanoparticles, respectively. The results from DLS indicated that the GA-treated nanoparticles formed smaller agglomerates as compared to the untreated samples over a 30-h time frame. Thermogravimetric analyses indicated an average weight loss of 23%, showing that GA has a strong affinity toward the iron oxide surface. GA most likely contributes to␣colloid stability via steric stabilization. It was determined that the adsorption of GA onto magnetite exhibits Langmuir behavior.     

DNA as a bioligand supported on magnetite for grafting palladium nanoparticles for cross-coupling reaction

The utilization of deoxyribonucleic acid (DNA) in nanotechnology is a promising area of research wherein the distinct properties of DNA are exploited for the design and development of new materials and applications. The biodegradability and natural profusion of DNA makes it highly suitable for use in various fields. In this report, we have treated DNA as a bioligand, supported on functionalized magnetite for the grafting of palladium (Pd) nanoparticles to make Pd-DNA bio-nanocatalyst. The Pd-DNA was subjected to Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Brunauer–Emmett–Teller, energy dispersive X-ray spectroscopy, vibrating sample magnetometry, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry analysis. The prepared Pd-DNA was found to be highly efficient in catalyzing Suzuki–Miyaura cross-coupling reaction with excellent yields when compared with commercially available palladium-based catalysts. Also, the Pd-DNA could be easily recovered from the reaction mass using an external magnet and recycled up to six times without substantial loss of activity. Furthermore, Felbinac, a non-inflammatory drug, was synthesized in quantitative yields using the Pd-DNA bio-nanocatalyst.     

Intramolecular O‐arylation using nano‐magnetite supported N‐heterocyclic carbene‐copper complex with wingtip ferrocene

Nano‐magnetite supported N‐heterocyclic carbene‐copper complex with wingtip ferrocene has been prepared via multi‐step procedure. The complex has been characterized by various analytical techniques such as fourier transform infrared (FT‐IR), fourier transform Raman (FT‐Raman), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) analysis. The catalytic activity of the complex has been exploited in intramolecular O‐arylation of o‐iodoanilides under heterogeneous conditions. The complex could be successfully recycled up to twelve consecutive cycles.     

Charge rearrangement in magnetite: from magnetic field induced easy axis switching to femtoseconds electronic processes

Magnetite is the oldest magnet and the first material where the concept of a strong correlations driven metal–insulator transition was suggested and found at T_V = 124 K in the so-called Verwey phase transformation. Recently, the structure below T_V was solved revealing subtle electronic structure in the form of trimeron lattice that, according to yet another recent communication, may be switched within femtosecond range. In this review article, we argue that the same change of trimeron lattice can be achieved by a magnetic field, in the phenomenon called the easy axis switching. The results of many of our experiments show that although this process is best viewed by magnetization studies, it is also reflected in magnetostriction, causes some changes in electronic transport and can be observed microscopically by NMR that proved electronic order alteration. All those facts suggest that the axis switching process observed and studied by us is intimately linked with the fast change of electronic trimeron order mentioned above.     

电感耦合等离子体原子发射光谱法(ICP-AES)测定铜磁铁矿中的Al,Ni,Cu,Mg,Pb,Zn 6种元素

建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定铜磁铁矿中Al,Ni,Cu,Mg,Pb,Zn6种元素的定量分析方法。通过实验选择396.152,216.555,324.754,285.213,220.353,213.857nm分别作为Al,Ni,Cu,Mg,Pb,Zn的分析谱线,方法的检出限均小于0.010μg/mL。与原子吸收光谱法进行对比,测定结果基本一致,方法的加标回收率在94%~105%,精密度实验结果表明,相对标准偏差(RSD,n=6)均小于5%,能满足日常对铜磁铁矿中杂质元素的检测要求。     

Functionalization and Evaluation of Inorganic Adsorbents for the Removal of Cadmium in Wastewater

This study presents the feasibility of using various functionalized substrates, Fe₃O₄ nanoparticles (NPs) and Al₂O₃ spheres, for the removal of Cd from aqueous solution. To improve the materials’ affinity to Cd, we explored four different surface modifications, namely (3-Aminopropyl) triethoxysilane (APTES), L-Cysteine (Cys) and 3-(triethoxysilyl) propylsuccinic anhydride (CAS). Particles were characterized by FTIR, FIB-SEM and DLS and studied for their ability to remove metal ions. Modified NPs with APTES proved to be effective for Cd removal with efficiencies of up to 94%, and retention ratios up to 0.49 mg of Cd per g of NPs. Batch adsorption experiments investigated the influence of pH, contact time, and adsorbent dose on Cd adsorption. Additionally, the recyclability of the adsorbent and its potential phytotoxicity and animal toxicity effects were explored. The Langmuir, Freundlich, pseudo-first-order and pseudo-second-order models were applied to describe the behavior of the Cd adsorption processes. The adsorption and desorption results showed that Fe₃O₄ NPs modified with APTES are promising low-cost platforms with low phytotoxicity for highly efficient heavy metal removal in wastewater.     

Time‐Resolved In Situ Synchrotron X‐ray Study and Large‐Scale Production of Magnetite Nanoparticles in Supercritical Water

A general solution : In situ synchrotron X‐ray scattering in a high‐pressure pulsed injection reactor (see picture) shows that magnetite nucleation and growth are temporally separated. Gram‐scale crystalline, pure phase, superparamagnetic magnetite nanoparticles were synthesized without surfactants in supercritical water in less than one hour using a laboratory‐scale continuous‐flow reactor.

     

Synthesis of Magnetite Nanoparticles by Precipitation with Forced Mixing

Synthesis of magnetite nanoparticles by precipitation with forced mixing is presented. Using this method it is easy to obtain a high product saturation degree and the constant pH value of the reaction system. The TEM and XRD measurments show that the average size of the product magnetite particles is less than 6.0-nm in the condition of [Fe²⁺]/[Fe³⁺]=0.5. The magnetic properties of the samples are discussed.     

Hexagonal Nanoarchitecture of Composite Monolayer of Magnetite Nanoparticles and Geminus Surfactant 1,3‐Propylenebis(dodecyldimethylammonium) Dibromide

Negatively charged magnetite nanoparticles with an average size of about 10 nm have been synthesized by a chemical coprecipitation method using sodium dodecyl benzene sulphonate as a surface modifying reagent. Composite Langmuir monolayer of Fe₃O₄ nanoparticles and geminus surfactant 1,3‐propylenebis(dodecyldimethylammonium) dibromide (C₁₂‐C₃‐C₁₂) was prepared on the subphase of Fe₃O₄ nanoparticle hydrosols. In the presence of the magnetite nanoparticles, the collapse pressure of the composite monolayer and the limited mean molecular area of C₁₂‐C₃‐C₁₂ are higher than those on pure water subphase. Transmission electron microscopy observation of a C₁₂‐C₃‐C₁₂/Fe₃O₄ nanoparticle complex shows that Fe₃O₄ nanoparticles and geminus surfactant had an unexpected hexagonal nanoarchitecture at the air‐liquid interface when the surface pressure of the composite monolayer increased to about 12 mN·m^?1. A mechanism for constructing the particular nanopatterned configuration of the C₁₂‐C₃‐C₁₂/Fe₃O₄ nanoparticle complex in the Langmuir layer directly from the unique molecular structure of the geminus surfactant and the interfacial interactions between C₁₂‐C₃‐C₁₂ and the components in the subphase was proposed.