Significance of Ionic Character Induced by Ga-Doped γ-Al2O3 on Polyethylene Degradation to the Precursors of Gasoline and Diesel Oil with a Trace Amount of Wax.

Polyethylene degradation has a significant ecological impact but is also economically beneficial because it generates fuels and useful chemical products. Our study mainly describes the cleavage of C-C and C-H bonds when polyethylene (dispersed in 1-octadecene) was low-temperature heat-treated in two steps, at 180 and 250 °C, for 24 h for each step. Finally, it was converted to a mixture of the precursors of gasoline and diesel oil with a trace amount of wax. A series of reactions resulted in cracking, dehydrogenation and oxidation, hence producing polycarboxylic acids and saturated and unsaturated hydrocarbons. ESI-MS analysis revealed that mixed oil consisted of low carbon number hydrocarbons and their derivatives of carboxylic acids, with the carbon number ranging from C-6 to C-18. In the trace amount of wax, complicated carboxylic acids and hydrocarbons with carbon number C-22 to C-58 were also identified. FT-IR analysis further confirmed the presence of carboxylic acid derivatives and double bonds in the degradation products. γ-Al2O3 nanorods effectively catalyzed the degradation process by enhancing the C-C chain length in the products. Lewis acid (Al) and Lewis base (oxygen) in the γ-Al2O3 induced ionic character of the C-C bond chain, which led to the efficient cracking of the C-C bond. Poor shielding effect, smaller atomic size and greater ionization energy made Ga a stronger Lewis acid compared to Al; hence, Ga-doped γ-Al2O3 catalyzed the degradation process even more effectively.

Synthesis of Uniform Size Rutile TiO2 Microrods by Simple Molten-Salt Method and Its Photoluminescence Activity.

Uniform-size rutile TiO2 microrods were synthesized by simple molten-salt method with sodium chloride as reacting medium and different kinds of sodium phosphate salts as growth control additives to control the one-dimensional (1-D) crystal growth of particles. The effect of rutile and anatase ratios as a precursor was monitored for rod growth formation. Apart from uniform rod growth study, optical properties of rutile microrods were observed by UV-visible and photoluminescence (PL) spectroscopy. TiO2 materials with anatase and rutile phase show PL emission due to self-trapped exciton. It has been observed that synthesized rutile TiO2 rods show various PL emission peaks in the range of 400 to 900 nm for 355 nm excitation wavelengths. All PL emission appeared due to the oxygen vacancy present inside rutile TiO2 rods. The observed PL near the IR range (785 and 825 nm) was due to the formation of a self-trapped hole near to the surface of (110) which is the preferred orientation plane of synthesized rutile TiO2 microrods.

Defectronics based photoelectrochemical properties of Cu2+ ion doped hematite thin film.

The concentration of guest elements (dopants) into host materials play an important role in changing their intrinsic electrical and optical properties. The existence of hetero-element induce defect in crystal structure, affecting conductivity. In the current work, we report Cu2+ ion into hematite in the defectronics point of view and their photoelectrochemical properties. Crystal distortion in the structure of hematite is observed as the amount of dopant increases. Among 1, 3 and 5 mol% of Cu2+ doped hematite, the existence of 1 mol% of Cu2+ ion into hematite crystal structure produce photocurrent value of 0.15 mA/cm2, IPCE value of ~ 4.7% and EIS value of ~ 2000 Ω/cm2 as best performances. However, further increasing dopants increases the number of interstitial defects, which cause the deformation of intrinsic lattice structure.

New avenues to efficient chemical synthesis of exchange coupled hard/soft nanocomposite magnet.

Nd-Fe-B ultrafine amorphous alloy particles were prepared by reaction of metal ions with borohydride in aqueous solution. Monodispersed Fe nanoparticles were synthesized under an argon atmosphere via thermal decomposition of Fe(2+)-oleate2. Exchange coupled Nd2Fe14B/Fe nanocomposite magnets have been prepared by self-assembly using surfactant. The crystal structure of the synthesized nanoparticles was identified by using X-ray powder diffraction (XRD). The size and shape of nanoparticles were obtained by transmission electron microscope (TEM). Thermogravimetry using a microbalance with magnetic field gradient positioned below the sample was used for the measurement of a thermomagnetic analysis (TMA) curve showing the downward magnetic force versus temperature.

One-Step Synthesis and Magnetic Phase Transformation of Ln-TM-B Alloy by Chemical Reduction.

Binary and ternary intermetallic alloy systems are of interest for a variety of academic and technological applications. Despite recent advances in synthesizing binary alloy, there are very few reports of ternary alloy related to lanthanide series. The purpose of this work is to contribute to ternary alloy systems such as lanthanide-transition metal-boron with a simple chemical method and analysis of its magnetic behavior. Ternary Nd-Fe-B amorphous alloy was successfully synthesized with borohydride. The magnetic behavior in the process of formation of ternary Nd-Fe-B alloy and Nd2Fe14B from amorphous phase alloy is reported. Compared with the synthesis of a transition metal, the existence of a lanthanide ion makes aggregates-like particles with a diameter of 2 nm possible in the formation of a nanosphere, which is a significantly important result in terms of acceleration of the reduction-diffusion reaction for the formation of ternary alloy. In the process of reduction and diffusion, the Nd phase is diffused into the Fe-based phase, and then the ternary Nd2Fe14B intermetallic compound is fabricated.

Vast magnetic monolayer film with surfactant-stabilized Fe3O4 nanoparticles using Langmuir-Blodgett technique.

Although several methods (e.g., self-assembly, spin coating, etc.) have been explored for making a monolayer film of nanoparticles, the monolayer on a substrate is typically smaller than 1 micromx1 microm in certain regions. The approach is not ideally suitable for generating a highly ordered and close-packed homogeneous vast monolayer of nanoparticles, which is potentially important for applications. In this report, the preparation of the vast monolayer films of Fe3O4 nanoparticles with a wide range such as that over 3.25 micromx3.95 microm is reported. Their TEM images showed a two-dimensional assembly of Fe3O4 nanoparticles, demonstrating the uniformity of these nanoparticles. The formation of a Langmuir monolayer of the oleic acid-coated Fe3O4 nanoparticles mixed with stearic acid molecules at the air/water interface and its stability were studied with a pressure-area isotherm curve. TEM and BAM studies demonstrated that increasing surface pressure resulted in a transition from well-separated domains of nanoparticles complex to well-compressed, monoparticulate layers.

Preparation and characterization of the antibacterial Cu nanoparticle formed on the surface of SiO2 nanoparticles.

Cu deposition on the surface of spherical SiO2 nanoparticles was studied to achieve the hybrid structure of Cu-SiO2 nanocomposite. SiO2 nanoparticles served as seeds for continuous Cu metal deposition. The chemical structure and morphology were studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscope energy dispersive X-ray (SEM-EDX), and a transmission electron microscope (TEM). The antibacterial properties of the Cu-SiO2 nanocomposite were examined with disk diffusion assays. The homogeneously formed Cu nanoparticles on the surface of SiO2 nanoparticles without aggregation of Cu nanoparticles showed excellent antibacterial ability.

Synthesis and characterization of crystalline FeCo nanoparticles.

The monodispersed FeCo nanoparticles were synthesized with borohydride as a reducing agent by coprecipitation method in aqueous solution. The composition and the size of FeCo nanoparticle was controlled by fitting the molar ratio of starting material, the reaction time and the falling rate. To prepare the crystallized nanoparticles, the amorphous FeCo nanoparticles were annealed at the different temperatures for 1 hr, respectively. The size of the crystalline FeCo nanoparticles was controlled in order to maintain the uniform size of 20 nm. The as-annealed FeCo alloy could get the highest Ms value of the powder which has been ever synthesized by coprecipitation or other chemical method. The size- and shape-controlled crystalline FeCo nanoparticles can be applied for spring magnet in order to get exchange coupling effect.

Synthesis of alpha-Fe nanoparticles by solventless thermal decomposition.

A new preparation for highly crystalline and monodisperse Fe3O4 nanoparticle is reported. This synthesis requires the use of rather complicated procedures including delicate control of surfactants ratios and inert reaction conditions due to the toxic and unstable nature of the precursors none the less because thermal decomposition methods were tried to synthesize monodispersed inorganic nanocrystallites until very recently. The synthesis of Fe3O4 nanocrystallites by using Fe(+2)-oleate2 complex was studied. The Fe(+2)-oleate2 complex was prepared from the reaction of iron chloride and sodium oleate in water. The thermal decomposition of the complex at the reduced pressure (0.3 torr) and about 300 degrees was done without any solvent. We demonstrated that a new solventless synthesis of size- and shape-monodisperse Fe3O4 nanoparticles depends on the amount of Na-oleate. And it is possible to remove the oleate ligand using reduction process. We confirmed that the nanoparticles changed from Fe3O4 to alpha-Fe phase obtained higher magnetic properties and crystallites by a vibrating sample magnetometer (VSM) and x-ray powder diffraction (XRD). Removal of the organic surfactant and other volatile components surrounding Fe3O4 nanoparticles was detected by fourier transform infrared spectroscopy (FT-IR).

Preparation of a vast CoFe2O4 magnetic monolayer by Langmuir-Blodgett technique.

The preparation of ultrathin films of CoFe2O4 nanocrystallites is reported. TEM images of them showed 2-dimensional assembly of particles, demonstrating the uniformity of these nanocrystallites. The formation of a Langmuir monolayer of the surface coated CoFe2O4 nanocrystallites with oleate at the air/water interface and its stability were studied with pressure-area isotherm curves and Brewster Angle Microscope (BAM) images. Surface pressure vs surface area isotherms and TEM studies demonstrated that the increasing surface pressure resulted in a transition from a complex with well-separated domains of nanocrystallites to well-compressed, monoparticulate layers, and, ultimately, to multiparticulate layers.

Kinetics of decolorization of spironaphthooxazine-doped photochromic polymer films.

Photochromic polymeric films were prepared by doping photochromic dye spironaphthooxazine into polymer resin gels such as polyurethane, vinyl copolymer, and copolymer of vinyl and nitorocellulose at different concentrations. All of the composite films show normal photochromism. The kinetics of the photochromism/decoloration in the films were quantified by fitting biexponential equations to their photochromic decay curves after irradiation. It was observed that the decoration process is faster in vinyl copolymer than that in the copolymer of vinyl and nitrocellulose and is the slowest in the case of polyurethane. The decoloration mechanisms of spironaphthooxazine in those polymeric matrixes have been discussed.

Solventless nanoparticles synthesis under low pressure.

In the present study, metal nanocrystals were obtained by the very easy, economical, and nontoxic thermal decomposition method and stabilized by coating oleate without any solvent. These nanocrystals have a highly crystalline structure due to a high decomposition temperature (~563-573 K) at low pressure and very narrow distribution. The prepared Fe3O4 nanocrystals were controlled by the annealing time and vacuum pressure. A TEM image of monodispersed Fe3O4 nanocrystals showed the 2D assembly of nanocrystals, demonstrating their uniformity. The particle size is 10.6 +/- 1.2 nm. TEM images of silver nanocrystals a showed 2D assembly with 9.5 +/- 0.7 nm. An electron diffraction image and X-ray diffraction of the nanocrystals showed the highly crystalline nature of metal nanocrystals.