ABSTRACT
An ultra-fast method to synthesize mesoporous magnetite (Fe(3)O(4)) nanoclusters is reported. These mesoporous magnetite can be used as a highly sensitive magnetic resonance imaging (MRI) probe. The nanoclusters were synthesized by reducing iron (III) acetylacetonate with hydrazine in ethylene glycol under microwave irradiation and only 5 min was needed in the synthesis. The diameter of the nanoclusters could be controlled effectively between 75 nm and 115 nm by increasing the amount of iron (III) acetylacetonate. Brunauer-Emmett-Teller (BET) results reveal a mesoporous structure and a large surface area of 72.3 m(2) g(-1). Cytotoxicity test performed in HepG2 cell line indicated that the as-prepared nanoclusters were non-cytotoxic. The nanoclusters exhibited an enhanced T(2) relaxivity value of 417.4±29.9 s(-1) mM(-1). In vitro and in vivo MRI confirmed the high sensitivity of the magnetite nanoclusters as MRI probe. The biodistribution of the nanoclusters in rat liver and spleen after intravenous injection was also investigated.
Subject(s)
Magnetite Nanoparticles/chemistry , Molecular Probes/chemistry , Animals , Hep G2 Cells , Humans , Liver/chemistry , Magnetic Resonance Imaging , Magnetite Nanoparticles/administration & dosage , Male , Molecular Probes/administration & dosage , Molecular Probes/chemical synthesis , Particle Size , Porosity , Rats , Rats, Sprague-Dawley , Spleen/chemistry , Surface Properties , Tissue DistributionABSTRACT
Magnetic FeNi3 nanochains were synthesized by reducing iron(III) acetylacetonate and nickel(II) acetylacetonate with hydrazine in ethylene glycol solution without any template under a rapid and economical microwave irradiation. The morphology and composition of the as-prepared products were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and elemental mapping. The size of the aligned nanospheres in the magnetic FeNi3 chains could be adjusted from 150 to 550 nm by increasing the amounts of the precursors. The length of the nanochain is about several tens of micrometers. The ratio of the precursors plays an important role in the formation of FeNi3 nanostructures. Magnetic measurement reveals that the FeNi3 nanochains show enhanced coercivity and saturation magnetization. The formation mechanism of the product is discussed. Toxicity tests of FeNi3 nanochains show that the as-prepared nanochains are nontoxic to zebrafish larvae. In vitro magnetic resonance imaging (MRI) confirms the effectiveness of the FeNi3 nanochains as sensitive MRI probes.
Subject(s)
Iron Compounds/chemistry , Nanostructures/chemistry , Nanostructures/radiation effects , Nickel/chemistry , Water/chemistry , Electromagnetic Fields , Hot Temperature , Iron Compounds/radiation effects , Materials Testing , Nickel/radiation effects , Particle SizeABSTRACT
In this study, the photodegradation of a typical nonaqueous phase liquid (NAPL)-trichloroethene (TCE) by ultraviolet irradiation was investigated. The decay of NAPL-TCE was studied in a RPR-200 Rayonet photochemical reactor, at three different monochromatic UV lamps (254, 300, and 350 nm). Among the three UV wavelengths used, the highest photodecay rate was obtained at 254 nm. The effect of the initial NAPL dosage was also analyzed to determine the photodecay of NAPL-TCE in batch experiments by ultraviolet irradiation at preselected wavelengths. The direct photolysis of NAPL-TCE followed two-stage pseudo first-order decay kinetics. The photodegradation rates of TCE were found to decrease with the increment of NAPL dosage. It is interesting to find that the NAPL dosage is critical to determine the process performance due to the NAPL size or cage effect, which will control the diffusion of TCE/intermediates between NAPL and aqueous phases and therefore the overall reaction rates. Mathematical models were developed for the prediction of the two-stage photodegradation, in which the remaining fraction of TCE (C/C0) in the system becomes predictable.
Subject(s)
Models, Chemical , Photolysis/radiation effects , Trichloroethylene/radiation effects , Ultraviolet Rays , Water/chemistry , Hydrogen-Ion Concentration/radiation effects , Kinetics , Reproducibility of Results , Solutions , Volatilization/radiation effectsABSTRACT
The photodegradation of trichloroethene (TCE) with or without nonaqueous phase liquids (NAPL) by ultraviolet irradiation in surfactant solutions was examined in this study. The photodecay of TCE was studied at monochromatic 254nm UV lamps. The effects of the type of surfactants, initial surfactant concentrations, pH levels and NAPL concentrations were examined to explore the photodecay of TCE. All the photodegradation of TCE followed pseudo-first-order decay kinetics at various conditions. It was found that Brij 35 overdose and higher initial pH levels may retard or inhibit the photodecay of TCE, mainly due to protons, intermediate generation and change of surfactant structure in the processes. The optimal condition for TCE photodecay was suggested based on the analysis of kinetics data, from which the reaction mechanism of TCE in the presence of NAPL form was also studied. In general, the reactions of TCE in micellar solution and NAPL pool can be considered as independent pathways due to the low molecule diffusion between the two phases.
