Magnetite

About: Magnetite is a research topic. Over the lifetime, 10277 publications have been published within this topic receiving 278071 citations.

Removal of Humic Acid in Water by Rice Hull Magnetic Activated Carbon and Magnetic Separation

Abstract: We have newly developed a rice hull magnetic activated carbon (RH-MAC) and studied its adsorption property for humic acid from water and high-gradient magnetic separation (HGMS) characteristics. Rice hull was impregnated with an iron nitrate solution and heat-treated in both nitrogen and carbon dioxide atmosphere. In these processes, the rice hull changed to activated carbon that had a lot of mesopores and nanosize magnetite inside. Magnetization of RH-MAC increased with an increase in iron nitrate concentration during the process and reached 20.8 Am 2 /kg at 0.5 T. In the adsorption examination, it was able to adsorb humic acid effectively, and the removal ratio achieved 97.6% from a humic acid solution of 50 mg/L. In HGMS studies, we used the magnetic wire filter rounded on a magnet drum with 0.5-T permanent magnet and the slurry of RH-MAC concentration of 100 mg/L. Consequently, 99.4% of RH-MAC in the slurry of 2 L was captured in the magnetic filter at flow rates of 230 mL/min. These results show that this water purification system has higher removal ratio of humic acid than that for current advanced water treatments.

Chains of Magnetite Crystals in the Meteorite ALH84001: Evidence of Biological Origin

Abstract: The presence of magnetite crystal chains, missing evidence for their biological origin, as well as five morphological characteristics incompatible with a nonbiological origin are demonstrated by high-power stereo backscattered scanning electron microscopy. Additional information is contained in the original extended abstract.

Magnetite authigenesis and diagenetic paleotemperatures across the northern Appalachian basin

Abstract: The concentration of magnetite in the Lower and Middle Devonian Helderberg and Onondaga carbonate formations varies in a distinct pattern along an east-west profile across New York State. Magnetite concentrations are uniformly low in the western half of the profile, increase sharply eastward to a peak value near Syracuse, and decrease farther east. The pattern strongly resembles previously reported variations in the extent of clay mineral diagenesis that reflect differences in paleotemperatures along the profile. Previous paleomagnetic studies have documented that the magnetite carries a well- defined magnetization of Pennsylvanian-Permian age, and magnetite authigenesis is therefore no younger than late Paleozoic. We attribute the correlation between high magnetite concentration and high illite content to temperature-dependent diagenesis triggered by orogenic fluids. The large proportion of secondary magnetite indicates that over most of the area, the mechanism of late Paleozoic remagnetization was principally chemical. Thermal effects played a less direct role in the remagnetization of the strata by controlling the extent of the chemical processes that resulted in overprinting of the original remanence.