Iron (III) oxide nanoparticles within the pore system of mesoporous carbon CMK-1: intra-pore synthesis and characterization

Iron (III) oxide nanoparticles were synthesized inside the pore system of mesoporous carbon CMK-1. This intra-pore synthesis was carried out using several cycles of wet impregnation, drying and calcination procedures. The existence of iron (III) oxide nanoparticles within the pore system was proved by powder X-ray diffraction, nitrogen physisorption, preservation of the host structure by Raman spectroscopy and transmission electron microscopy. Finally, the local structure of the iron oxide was determined by X-ray absorption spectroscopy.     

Homonuclear tris-dithiocarbamato ruthenium(III) complexes as single-molecule precursors for the synthesis of ruthenium(III) sulfide nanoparticles

Tris(N-phenyldithiocarbamato) ruthenium(III) complexes, [Ru(L¹)₃] (1); tris(N-(4-methylphenyl)dithiocarbamato)) ruthenium(III), [Ru(L²)₃] (2); and tris(N-(4-methoxyphenyl)dithiocarbamato)) ruthenium(III), [Ru(L³)₃] (3) were synthesized and characterized by elemental analysis, thermogravimetric analysis, FTIR, UV–VIS and NMR spectroscopy. TGA analyses show major degradation of all complexes in the range 120–350°C, leading to the formation of residual weight corresponding to ruthenium (III) sulfides. The ¹H-NMR spectra of the ligands and complexes are in agreement with the proposed structures. FTIR studies confirmed that the ligands coordinate the Ru³⁺ ion in a bidentate chelating mode. The complexes were thermolysed at 180°C to prepare hexadecylamine-capped Ru₂S₃ nanoparticles. Powder X-ray diffraction patterns revealed the formation of hexagonal-phase Ru₂S₃ nanoparticles with average crystallite sizes ranging from 8.3 to 9.5?nm. TEM images showed the crystalline clusters with shapes ranging from square to hexagonal, while SEM images elucidated that the particles were agglomerated. Energy-dispersive X-ray spectra confirmed the presents of Ru₂S₃ nanoparticles.     

Crosslinking reaction of polyacrylamide with chromium(III)

Summary The crosslinking of initially non-hydrolyzed polyacrylamide with chromium in its +3 valence state was investigated in this work. IR spectra showed that the gelation occurred when the polyacrylamide was hydrolyzed, which implies that the gelation should take place at elevated temperature under neutral condition. The gelation process was monitored by means of viscosity measurement. The addition of acetic acid to the system might lead to the delay of gelation, owing to the synergistic effect of chelating with Cr(III) and acidity.     

In situ synthesis of iron oxide nanoparticles on poly(ethylene oxide) nanofibers through an electrospinning process

Iron oxide nanoparticle coated poly(ethylene oxide) nanofibers as organic–inorganic hybrids with 200–400‐nm diameters were prepared by the in situ synthesis of iron oxide nanoparticles on poly(ethylene oxide) nanofibers through the electrospinning of a poly(ethylene oxide) solution having Fe²⁺ and Fe³⁺ ions in a gaseous ammonia atmosphere. Transmission electron microscopy analysis proved the presence of iron oxide nanoparticles on the polymer nanofibers. The thermal properties of the nanofiber mat were also studied with differential scanning calorimetry and thermogravimetric analysis techniques. X‐ray diffraction showed that the formed iron oxide nanoparticles were maghemite nanoparticles. The results were compared with those of the electrospinning of a poly(ethylene oxide) solution having Fe²⁺ and Fe³⁺ ions and a pure poly(ethylene oxide) solution in an air atmosphere. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Catalytic gas-phase fluorination of 1,1,1-trifluoro-2-chloroethane over chromium (III) oxide: Preparation of hydrofluoroalkanes

The transformation of CF₃CH₂Cl over bulk chromium(III) oxide, fluorinated or not, leads mainly to the fluorination product CF₃CH₂F and to the alkene CF₂=CHCl. In the presence of HF, CF₃CH₂F is the main product. In absence of HF this product is also obtained with HF formed in the elimination reaction of CF₃CH₂Cl to CF₂=CHCl. At the same time a part of HF is used for the fluorination of chromium oxide. The XPS analysis of fluorinated catalysts with HF gives surface fluorine atomic contents which correspond to a F/Cr ratio of 0.36. A survey of the effect of partial pressures of HF and of CF₃CH₂Cl shows a zero order for HF and a 0.6 order for CF₃CH₂Cl. The fluorination reaction could occur on a partially fluorinated chromium(III) oxide involving HF oligomer species previously postulated by Rowley et al. [L. Rowley, J. Thomson, G. Webb and J.M. Winfield, Appl. Catal. A, 79 (1991) 89–103].     

Characterization of iron(III) oxide nanoparticles prepared by using ammonium acetate as precipitating agent

The effect of precipitating agent on the preparation of iron(III) oxide particles was investigated. Iron(III) oxide particles were prepared by precipitation of aqueous ferric nitrate solution by using ammonium acetate and ammonium hydroxide as precipitating agents. Particle size, shape, chemical composition, crystalline formation rate, crystallinity and magnetic property were measured for Fe₂O₃ particles obtained by precipitating with ammonium acetate, and compared with those of particles formed by using ammonium hydroxide. TGA, DTA, IR, XRD, TEM and VSM were used to characterize the particles. The nanoparticles synthesized with ammonium acetate showed a narrow size distribution, spherical shape, fast crystalline formation rate, high crystallinity and complete hysteresis loop. The better properties of particles formed by using ammonium acetate were originated from the chelating effect of carboxylate ions and higher crystallinity than those synthesized with ammonium hydroxide.     

The electrodeposition of chromium from chromium(III) solutions — a study using microelectrodes

Potential sweep and pulse experiments at a carbon microdisc electrode (radius 4 m) have been used to investigate chromium plating from aqueous solutions of chromic ions containing sulphate or thiocyanate ions and buffered at pH 3.3. While chromium deposition occurs in many media, it is shown that the plating reaction is always in competition with other cathodic reactions including hydrogen evolution. This leads to loss in current effciency and, in some circumstances, to precipitation of chromic hydroxide on the cathode and, hence, contamination of the metal. In addition, it is demonstrated that the chromium(III) exists in solution as mixtures of complexes, not all of which are electroactive within the accessible potential range. Hence the investigation confirms that the quality of electroplates will vary strongly with the choice of medium. A commercial chromium(III) plating bath, Envirochrome, has also been studied and it is concluded that its properties are superior to simple sulphate or thiocyanate solutions.     

Hydrothermal synthesis,crystal structure and spectroscopic properties of a novel 3D chromium(III) complex

The hydrothermal synthesis of CrCl₃·6H₂O, NaOH, 2,6-dipicolinic acid (H₂dpa), salicylic acid (HSAL) in water and ethanol at 140 °C for 5 days yields a novel 3D coordination polymer NaCr(C₇H₃O₄N)₂(H₂O)₂ (1). In the complex, each Cr center is in a distorted octahedral environment, and coordinates to two nearly perpendicular dpa anions, which act as tridentate ligands. Na(I) is in a compact sixfold coordination with three non-coordination carbonyl oxygen atoms of neighboring asymmetric units, a carboxylate oxygen atom shares coordination with Cr(III) and two aqueous. Two adjacent asymmetric units are linked together through Na–O and a set of intermolecular hydrogen bonds, which generates the finally 3D supermolecular network structure.     

Removal of chromium (III) and cadmium (II) from aqueous solutions

Chromium and cadmium are toxic heavy metals present in wastewaters from a variety of industries. A strong cationexchange resin, Amberlite IR 120, was used for the removal of chromium and cadmium. The resin was prepared in two different cationic forms, as Na⁺ and H⁺. The optimum conditions were concentration, pH, stirring time and resin amount. The concentration range was between 2–50 mg/L, pH range between 2–10, stirring time between 5–60 min, and the amount of resin was from 50–1000 mg. Exchange capacities, moisture content and optimum conditions of this resin were determined in a batch system. The stirring speed was 2000 rpm during all of the batch experiments. The initial and final chromium and cadmium amounts were determined by atomic absorption spectrophotometry. The optimum conditions were found to be a concentration of 20 mg/L, pH of 5.5, stirring time of 20 min and 100 mg of resin. The results obtained show that the Amberlite IR 120 strong cation-exchange resin performed well for the removal and recovery of chromium and cadmium.     

Plasma-electrochemical synthesis of europium doped cerium oxide nanoparticles

In the present study,a plasma-electrochemical method was demonstrated for the synthesis of europium doped ceria nanoparticles.Ce(NO3)3· 6H2O and Eu(NO3)3·5H2O were used as the starting materials and being dissolved in the distilled water as the electrolyte solution.The plasma-liquid interaction process was in-situ investigated by an optical emission spectroscopy,and the obtained products were characterized by complementary analytical methods.Results showed that crystalline cubic CeO2:Eu3+ nanoparticles were successfully obtained,with a particle size in the range from 30 to 60 nm.The crystal structure didn't change during the calcination at a temperature from 400℃ to 1000℃,with the average erystallite size being estimated to be 52 nm at 1000℃.Eu3+ ions were shown to be effectively and uniformly doped into the CeO2 lattices.As a result,the obtained nanophosphors emit apparent red color under the UV irradiation,which can be easily observed by naked eye.The photoluminescence spectrum further proves the downshift behavior of the obtained products,where characteristic 5Do → 7F1,2,3 transitions of Eu3+ ions had been detected.Due to the simple,flexible and environmental friendly process,this plasma-electrochemical method should have great potential for the synthesis of a series of nanophosphors,especially for bio-application purpose.     

Optimization of the thermomechanical behavior of a poly(chromium(III) trisphosphinate)

A two-component reactive system consisting of a poly(chromium(III) bisphosphinate) and dioctylphosphinic acid reacts to form a poly(chromium(III) trisphosphinate). Extensive thermomechanical hysteresis is displayed throughout the temperature range ?180°C to >300°C by specimens containing filaments of glass. Thermal pretreatment to about 400°C (the limit of thermal stability) eliminated these instabilities. These results correlate with the reported brittle and tough character of films of the poly(chromium (III) bisphosphinate) and poly(chromium (III) trisphosphinate), respectively. Regardless of thermal history (between 200°C and 400°C), the polymer system displayed three major transition regions: the glass transition centered at about 0°C, another centered at about 230°C, and a third at about ?200°C.     

Adsorption of copper(II) and chromium(III) ions onto amidoximated cellulose

Chemical modification of cellulose powder is performed by successive reactions with acrylonitrile in an alkaline medium followed by aqueous hydroxylamine to prepare amidoximated cellulose. Due to complexation, the amidoxime groups immobilize heavy cations from buffered solutions at various pH values. The capacity of adsorption for Cu(II) and Cr(III) ions is related to the amount of amidoxime groups in the support and to the metal concentration of the polluted solution. The formation of a 1/1 complex is proved by the adsorption limit values. Desorption of the cations is possible by treatment with a stronger complexing agent such as ethylenediaminetetracetic acid. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1624–1631, 2000     

Effective adsorption of ciprofloxacin antibiotic using powdered activated carbon magnetized by iron(III) oxide magnetic nanoparticles

Journal of Porous Materials - In the present work, the adsorption performance of powdered activated carbon magnetized by iron(III) oxide magnetic nanoparticles (PAC@Fe3O4-MN) for the removal of...     

Bismuth(III) subgallate trihydrate synthesis

The syntheses of bismuth(III) subgallate trihydrate C₆H₂(OH)₃COOBiO · 3H₂O via its precipitation from bismuth nitrate solutions with aqueous gallic acid and via the reaction between solid bismuth oxohydroxonitrate, oxohydroxoperchlorate, oxocarbonate, or oxochloride and a gallic acid solution have been investigated by X-ray diffraction, thermal analysis, and IR and Raman spectroscopy. The conditions for obtaining a high-purity product with a large specific surface area have been determined.     

Effect of Cr(III) solution chemistry on electrodeposition of chromium

This work provides a new insight into the interaction of urea with formate during the chromium electrodeposition from a sulphate-based Cr(III) solution. The influence of solution chemistry on chromium electrodeposition in a Cr(III) bath containing sodium formate and urea as complexing agents was studied by FT-IR, XPS and AFM. The results show that good quality Cr coatings may be obtained only in those cases when the secondary ligand with the carbamidic group predominates over urea in the electrolyte. This suggests that electrodeposition of good quality chromium deposit is possible due to the formation of active chromium–carbamid complexes [Cr(carbamid)_n(H₂O)_6-n ]³⁺. These complexes delay the formation of the stable oligomeric species, and thus provide a prolonged working lifetime in the Cr(III) formate-urea electrolyte.     

A pigment based on coprecipitated chromium(III) and copper(II) hydroxides

The results of experiments on coprecipitation of copper and chromium hydroxides are presented. It is established that the final product of coprecipitation is an individual hydroxide compound that transforms when heated into Cu₂Cr₂O₄ and CuCr₂O₄ spinels which preserve their stability up to 1200°C. The pigment can be used for decorating porcelain and ceramic tile.Translated from Steklo i Keramika, No. 7, pp. 21 – 23 , July, 1996.     

Arsenic adsorption using copper (II) oxide nanoparticles

Arsenic poisoning is a major problem in today's life. To reduce its concentration in drinking water, different metal based compounds were explored as arsenic adsorbents. In the present study, copper (II) oxide nanoparticles were prepared by thermal refluxing technique and used as an adsorbent for arsenic removal from water. Characterization of the adsorbent using TEM, BET, XRD and FTIR implied that the prepared adsorbent was in nano size and had excellent adsorption behavior with surface area of 52.11 m²/g. Systematic adsorption experiments were carried out with different process parameters such as contact time, adsorbent mass, pH, temperature and stirring speed and found that copper (II) oxide had very good efficiency towards arsenic adsorption. Thermodynamic parameters and adsorption kinetics were studied in detailed to know the nature and mechanism of adsorption. Results showed that the adsorption process followed pseudo second order kinetic and endothermic behavior. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. The adsorption process followed Langmuir isotherm with an adsorption capacity of 1086.2 μg/g. A regeneration study was proposed in order to reuse the adsorbent for better economy of the process. Finally, a process design calculation is reported to know the amount of adsorbent required for efficient removal of arsenic from aqueous medium.     

Photochemical properties of sintered iron (III) oxide

The photochemical properties of vacuum deposited films and of sintered and doped iron(III) oxide have been studied. From the wavelength dependence of the photopotentials we know that photo-activity of the electrochemical cell with the iodine/iodide redox couple starts at the same wavelength, 600–650 nm, as the absorption of light and the photoconductivity of vacuum deposited films. Open circuit potentials of about 400 mV have been observed with the visible radiation from a 150 W xenon lamp. In neutral solution photocorrosion was too small to be observed.     

Greener synthesis and medical applications of metal oxide nanoparticles

Over the past decade, the subject of “greener chemistry" and chemical processes has been emphasized. The “greener chemistry” improves environmental efficiency in reducing the consumption of resources and energy and achieving a stable economic development of the environment. Nanotechnology is investigating nanoscale materials that have applications in the area of biotechnology and nanomedicine alongside several other significant applications such as cosmetics, drug delivery, and biosensors. The different shapes and sizes of nanoparticles can be synthesized with physical, chemical, or biological methods. The tendency to produce nanomaterials, especially metal oxides, and use them, is increasing because of their exciting properties in the nanoscale. However, metal oxide nanoparticles produced by chemical methods have significant concerns due to hazardous and toxic chemicals and their environmental damage. The production of metal oxide nanoparticles using the principles of greener chemistry has found a special place in research. Increased awareness of greener chemistry and biological processes has necessitated using environmentally friendly methods for the production of non-toxic nanomaterials. Plants and polymeric materials as renewable and inexpensive sources have received particular attention to prepare nano biomaterials. The use of plants to synthesize metal oxide nanoparticles because of the non-use toxic pollutants is one of the environmentally friendly methods, and that's why this type of synthesis is called greener synthesis. In this review, we exhibit a total sight of greener synthesis methods for producing metal oxide nanoparticles and their medical applications.