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The magnetism of pentlandite surface was enhanced through the selective precipitation of micro-fine magnetite fractions on pentlandite surfaces. This was achieved through adjustment of slurry pH and addition of surfactants. The results showed that at pH 8.8 with the addition of 100 g/t sodium hexametaphosphate, 4.5 L/t oleic acid, and 4.5 L/t kerosene, significant amount of fine magnetite particles adhered to the pentlandite surface, while trace amount of coating was found on serpentine surfaces. Thus, the magnetism of pentlandite was enhanced and pentlandite was well separated from serpentine by magnetic separation under the magnetic field intensity of 200 kA/m. Scanning electron microscopy (SEM) and zeta potential measurement were performed to characterize changes of mineral surface properties. Calculations of the extended Derjaguin–Landau–Verwey–Ocerbeek (EDLVO) theory indicated that, in the presence of surfactants the total interaction energy between magnetite and pentlandite became stronger than that between magnetite and serpentine. This enabled the selective adhesion of magnetite particles to pentlandite surfaces, thereby enhancing its magnetism. 相似文献
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Hematite pellet is required to be indurated at very high temperature to achieve its good strength as there is no exothermic heat of oxidation unlike magnetite. As mill scale contains mainly FeO and Fe3O4, any minor amount of its addition in pellet can provide in situ heat and enhance diffusion bonding and sintering. In this study, the mill scale generated in steel plant is added as magnetite input in hematite pellet both in acidic and in basic condition. It has been found that in fluxed pellet, mill scale can improve the properties of pellet. In acidic pellet, the induration temperature has been reduced to a great extent (1250–1275°C) and all properties have been found to be improved due to the addition of 15% mill scale. Mill scale shows enough potential to eliminate the flux addition in producing blast furnace quality pellet from hematite ore. Thus, the flux free acidic pellet has been developed even at very low temperature (1275°C) of induration. 相似文献
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In this study, 2,4-DNPH coated magnetite was used for removal of As(V) and V(V) ions from aqueous solution. The synthesized nanoparticles were characterized by XRD analysis, FT-IR, SEM, and SEM-EDXS measurement. The size of the nanoparticles according to SEM was obtained as around 20–35 nm. Equilibrium isotherm data showed that the Langmuir–Freundlich model was in a good agreement with the experimental data according to high correlation coefficient. The maximum adsorption capacities of As(V) and V(V) on adsorbent were 338.4 and 266.8 mg g?1, respectively. Kinetic study showed that the fractal like-PSO model was appropriate to describe the adsorption process. The optimum pH was obtained to be 7 and 5 for As(V) and V(V) ions, respectively. 相似文献
25.
Anna Fischer Manuel Schmitz Barbara Aichmayer Peter Fratzl Damien Faivre 《Journal of the Royal Society Interface》2011,8(60):1011-1018
Magnetosome biomineralization and chain formation in magnetotactic bacteria are two processes that are highly controlled at the cellular level in order to form cellular magnetic dipoles. However, even if the magnetosome chains are well characterized, controversial results about the microstructure of magnetosomes were obtained and its possible influence in the formation of the magnetic dipole is to be specified. For the first time, the microstructure of intracellular magnetosomes was investigated using high-resolution synchrotron X-ray diffraction. Significant differences in the lattice parameter were found between intracellular magnetosomes from cultured magnetotactic bacteria and isolated ones. Through comparison with abiotic control materials of similar size, we show that this difference can be associated with different oxidation states and that the biogenic nanomagnetite is stoichiometric, i.e. structurally pure whereas isolated magnetosomes are slightly oxidized. The hierarchical structuring of the magnetosome chain thus starts with the formation of structurally pure magnetite nanoparticles that in turn might influence the magnetic property of the magnetosome chains. 相似文献
26.
A magnetic solid phase extraction was developed for preconcentration of Cu(II) as a 4-bromo-2-(2,4-dichloro-phenylimino)-phenol complex on Fe3O4/SiO2 nanoparticles prior to its determination by atomic absorption spectroscopy. The effect of different parameters influencing the formation of the Cu complex and the extraction efficiency of the Cu complex were studied. Under optimal conditions, the calibration graph showed linearity in the range of 0.946–700 µg L?1 (R2 = 0.9995) of Cu(II). The limit of detection and relative standard deviation of the method (n = 6) were 0.283 µg L?1 and 3.0%, respectively. The method was successfully applied to determine copper (II) in water samples. 相似文献
27.
Ana Rešček Zlata Hrnjak-Murgić Nino Dimitrov Kata Galić 《Polymer-Plastics Technology and Engineering》2016,55(14):1450-1459
Polyethylene (PE) was modified and prepared as double-layer polyethylene/polycaprolactone (PE/PCL) film. Magnetite and casein were added to the PCL-coating film to improve barrier properties and prevent destruction of basic structure of primary polymer PE. Significant improvements were observed with regards to mechanical (tensile strength, elongation at break) and thermal properties, while barrier (O2 permeability) properties were slightly improved. Overall migration values into acetic acid were lower (from 1 to 4.6 mg/dm2) than the upper limit set by the legislation. Specific migration of iron in PE/PCL-Fe samples is also below (µg/L) specific migration limit value set by the legislation (mg/kg). 相似文献
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Joanna Kisaa Anna Tomaszewska Adriana Barylyak Yaroslav Bobitski Maciej Balawejder 《International journal of molecular sciences》2022,23(7)
Flame retardants have attracted growing environmental concern. Recently, an increasing number of studies have been conducted worldwide to investigate flame-retardant sources, environmental distribution, living organisms’ exposure, and toxicity. The presented studies include the degradation of 4,4′-isopropylidenebis(2,6-dibromophenol) (TBBPA) by ozonolysis and photocatalysis. In the photocatalytic process, nano- and micro-magnetite (n-Fe3O4 and μ-Fe3O4) are used as a catalyst. Monitoring of TBBPA decay in the photocatalysis and ozonolysis showed photocatalysis to be more effective. Significant removal of TBBPA was achieved within 10 min in photocatalysis (ca. 90%), while for ozonation, a comparable effect was observed within 70 min. To determine the best method of TBBPA degradation concentration on COD and TOC, the removals were examined. The highest oxidation state was obtained for photocatalysis on μ-Fe3O4, whereas for n-Fe3O4 and ozonolysis, the COD/TOC ratio was lower. Acute toxicity results show noticeable differences in the toxicity of TBBPA and its degradation products to Artemia franciscana and Thamnocephalus platyurus. The EC50 values indicate that TBBPA degradation products were toxic to harmful, whereas the TBPPA and post-reaction mixtures were toxic to the invertebrate species tested. The best efficiency in the removal and degradation of TBBPA was in the photocatalysis process on μ-Fe3O4 (reaction system 1). The examined crustaceans can be used as a sensitive test for acute toxicity evaluation. 相似文献