Oxana V. Kharissova

Iron-containing nanomaterials: synthesis, properties, and environmental applications

Available data on the iron-containing nanomaterials are reviewed. Main attention is paid to the following themes: synthetic methods, structures, composition and properties of the nano zerovalent iron (NZVI), and polymorphic forms of iron oxides and FeOOH. Synthetic methods summarized here include a series of physico-chemical methods such as microwave heating, electrodeposition, laser ablation, radiolytical techniques, arc discharge, metal-membrane incorporation, pyrolysis, combustion, reverse micelle and co-deposition routes. We have also included a few “greener” methods. Coated, doped, supported with polymers or inert inorganic materials, core–shell nanostructures, in particular those of iron and its oxides with gold, are discussed. Studies of remediation involving iron-containing nanomaterials are discussed and special attention is paid to the processes of remediation of organic contaminants (chlorine-containing pollutants, benzoic and formic acids, dyes) and inorganic cations (Zn(II), Cu(II), Cd(II) and Pb(II)) and anions (nitrates, bromates, arsenates). Water disinfection (against viruses and bacteria), toxicity and risks of iron nanomaterials application are also examined.

Dispersion of carbon nanotubes in water and non-aqueous solvents

Contemporary methods for dispersion of carbon nanotubes in water and non-aqueous media are discussed. Most attention is paid to ultrasonic and plasma techniques and other physical techniques, as well as to the use of surfactants, functionalizing and debundling agents of distinct nature (elemental substances, metal and organic salts, mineral and organic acids, oxides, inorganic and organic peroxides, organic sulfonates, polymers, dyes, natural products, biomolecules, and coordination compounds). Special studies on CNTs solubilization are examined.

Solubilization, dispersion and stabilization of magnetic nanoparticles in water and non-aqueous solvents: recent trends

Recent achievements in the solubilization and stabilization of magnetic nanoparticles (MNPs) are reviewed. The majority of reported MNPs correspond to iron-based {nZVI, superparamagnetic iron oxides (SPIONs), core–shell Fe/Au or FexOy/Au nanoparticles and ferrites} nanoparticles, with a few numbers corresponding to MnO and cobalt nanoparticles. Magnetic nanoparticles can be solubilized in water or non-aqueous solvents for short or long time periods. The main approaches for MNP solubilization are discussed, namely, suitable choice of precursors, pH, surfactants/coating agents, and solvents, as well as functionalizing agents. MNPs are generally solubilized by functionalization with water-soluble compounds/moieties (in particular, sulfonic acid disodium salts, soluble polymers, porphyrins and calixarenes), under conditions of the thermal decomposition of low stability metal complexes, coprecipitation, microwave heating, and by ultrasonication. The polyol strategy is frequently applied to increase MNP solubility. The stabilization of MNPs in solutions could be achieved with the help of inorganic, monomeric and polymeric compounds.

Variations of interlayer spacing in carbon nanotubes

The analysis of previous classic and recent reports on the interlayer distances in MWCNTs is described in this review. Simulations on interlayer spacing, applications of Raman spectroscopy, X-ray and neutron diffraction methods, influence of synthesis methods, heat and radiation (gamma-rays, electron and ion beams) treatments are discussed, as well as the polygonization and intercalation of CNTs. It is shown that the spacing values of DWCNTs and MWCNTs vary from 0.27 up to 0.42 nm. The most common values are in the range of 0.32–0.35 nm and do not strongly depend on the synthesis method. Diameter of CNTs and the symmetry of layers influence the interwall spacing.

Magnetic adsorbents based on micro- and nano-structured materials

Micro- and nano-sized magnetic adsorbents based on elemental metals, iron oxides, and ferrites and supported by inorganic (carbon, graphene, silica, and zeolites) or organic (macromolecules, polysaccharides, polymers, and biomolecules) compounds are reviewed. The main focus is on magnetic hydrogels, xerogels, and aerogels due to their high number of environmental and biomedical applications. The roles of carbohydrates and polysaccharides (starch, alginic acid, chitosan, etc.) in the stabilisation of magnetic nanoparticles and the use of the formed composites for adsorption purposes are described. Magnetic adsorbents are mainly used for heavy metal removal, for the separation, destruction and adsorption of oil, dyes, toxic organic compounds, several biomolecules and drugs, as well as in a wide variety of catalytic processes. These last applications of magnetic adsorbents, particularly ferrites, are emphasised. The main advantage of magnetic absorbents for these or other possible applications is that the adsorbent or catalyst can be easily removed from the reaction medium after adsorption or reaction completion via a simple magnet. Magnetic behaviour studies of magnetic adsorbents are also discussed.

Ultrasmall particles and nanocomposites: state of the art

Synthesis, properties, and applications of ultrasmall particles (USPs, size/diameter <10 nm), so-called “ultrasmall nanoparticles”, are reviewed. USPs mainly consist of nanoparticles (with or without functionalization) of metallic gold, as well as iron and gadolinium oxides, all of which have important biomedical applications. Several other elemental metals and non-metals, oxides, salts, a few polymers and coordination compounds have also been obtained as USPs. Their main applications include biomedical uses {Magnetic Resonance Imaging (MRI) contract agents, virus inactivation, immunoassay labeling, etc.}, varieties of catalysis, hydrogen sorption, as magnetic devices, ultrasmall transistors, sensors for gases or biological objects, parts of solar cells and batteries, among others. Recent approaches, such as size-focusing methodology, for obtaining USPs and preventing their further agglomeration, are discussed.

Recent advances on ditopic ligands

Recent (2000–2009) achievements on ditopic ligands are reviewed. The ditopic ligands are mainly represented by N-, P-, O-, and S-containing organic molecules or their N, O-, N, S-, and N, P-combinations with azine, azole, amine, azide, β-diketone, crown ether, carboxylate, phenanthroline, oxazoline, phosphole, and thiophene moieties, among others. A series of mono- and polynuclear transition and f-metal complexes with these ligands, in particular cluster- and supramolecular unit-containing complexes, have been obtained and characterized spectroscopically and electrochemically.

Synthesis Techniques, Properties, and Applications of Nanodiamonds

Synthesis methods (ion and laser bombarding, CVD, hydrothermal, ultrasonic, electrochemical, and detonation techniques) for obtaining various forms of nanodiamonds (NDs) are generalized. Structure, physical and chemical properties, functionalization of NDs and composites on its basis are discussed, as well as their applications in medicine, electrochemistry, materials chemistry and technology.

Microwave Hydrothermal and Solvothermal Processing of Materials and Compounds

Hydrothermal synthesis (or hydrothermal method) includes the various techniques of fabrication or crystallizing substances from high-temperature aqueous solutions at high vapor pressures. In case of crystallization processes, the hydrothermal synthesis can be defined as a method of synthesis of single crystals that depends on the solubility of minerals in hot water under high pressure. The crystal growth is performed in an apparatus consisting of a steel pressure vessel called autoclave, in which a nutrient is supplied along with water. A gradient of temperature is maintained at the opposite ends of the growth chamber so that the hotter end dissolves the nutrient and the cooler end causes seeds to take additional growth.

State of the Art of the Bi- and Trimetallic Nanoparticles on the Basis of Gold and Iron

Recently reported patents and experimental articles on the synthesis, properties, and main applications of core-shell nanoparticles, containing iron or its oxides and gold, as well as trimetallic systems on their basis, are reviewed. These nanostructures were obtained by a series of methods, including reduction in reverse micelles, decomposition of organometallic compounds, electron-beam, laser and gamma-irradiation, sonolysis and electrochemical methods. (Fe or Fe(X)O(y))/Au nanoparticles are subject to be functionalized with organic moieties, may expand their main applications, which consist of catalysis, biological and biomedical uses.