Magnetite

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

Encapsulated superparamagnetic particles

Abstract: Stable, encapsulated superparamagnetic magnetite particles having a narrow particle size distribution with average particle diameters in the range of from about 50 Å to about 350 Å are prepared by forming an aqueous dispersion of magnetite particles having the above particle size characteristics in the presence of a surfactant, coacervating a mixture of gelatin and a carboxyl containing hydrophilic polymer such as gum arabic to form a thin coating of coacervate on the magnetite particles and crosslinking the coacervate coating with a gelatin hardener such as glutaraldehyde.

Sorption and reduction of neptunium(V) on the surface of iron oxides

Abstract: Sorption and desorption experiments of Np on magnetite and hematite under aerobic and anaerobic conditions were carried out to investigate the possibility of reduction of Np(V) to Np(IV) at pH 4 to 8 within 7 days. The amount of sorbed Np on magnetite under anaerobic conditions was about 2 or 3 times greater than that under aerobic conditions. Furthermore, the results of desorption experiments indicated that the dominant sorption behavior of Np on magnetite under anaerobic conditions was quite different from that under aerobic conditions. The oxidation state of Np sorbed on the iron oxides was determined by extraction technique using 0.5 M TTA in xylene and 2.0 M HNO 3 solution from the solid phase after sorption experiment. 90% and 10% of extracted Np was Np(IV) for magnetite system under anaerobic and aerobic conditions, respectively. On the other hand, almost 100% of extracted Np was Np(V) for hematite system under both aerobic and anaerobic conditions. These results indicated that Np(V) was reduced to Np(lV) by Fe(II) in magnetite. Redox reaction between Np(V) and Fe(II) was also studied in homogeneous solution without solid to decide if Fe(II) ions released from magnetite into silution or Fe(II) on the solid cause the reduction. Only 6% of Np(V) was reduced by Fe(II) at pH = 4 and 6 even after 7 days. According to this result, it was conjectured that the reduction of Np(V) to Np(IV) takes place not in the liquid phase by Fe(II) ion but on the surface of magnetite.

Oxidation of the LaBlache Lake Titaniferous Magnetite Deposit, Quebec

Abstract: The LaBlache Lake titaniferous-magnetite deposit was studied to determine, first, the cause of oxidation-exsolution of ilmenite from titaniferous magnetite in plutonio rocks and, second, the effect of oxidation on oxygen-isotope exchange, application of the magnetite-ilmenite geothermometer-oxygen barometer, and the distribution of manganese between titaniferous magnetite and ilmenite. The compositions and modal proportions of coexisting titaniferous magnetite and ilmenite (determined by electron-probe X-ray microanalysis and by weighing mineral separates) correlate closely with that predicted according to progressive oxidation-exsolution of ilmenite from titaniferous magnetite in a system open only to oxygen. The igneous titaniferous magnetite probably contained up to about the equivalent of 5 weight per cent of $R_{2}O_{3}$ as excess oxygen. This $R_{2}O_{3}$ probably exsolved as ilmenite above about 800° C. An additional 7 per cent of ilmenite may have resulted from oxidation-exsolution by trapped wate...