Topic
Magnetite
About: Magnetite is a research topic. Over the lifetime, 10277 publications have been published within this topic receiving 278071 citations.
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TL;DR: In this paper, superparamagnetic silica-coated magnetite (Fe3O4) nanoparticles with immobilized metal affinity ligands were prepared for protein adsorption.
162 citations
TL;DR: The results suggest that arsenic adsorption to the nanoparticles was not significantly affected by the pH, ionic strength and temperature in the ranges tested, which are typical of most potable water sources.
Abstract: Little work has been conducted on the adsorption of arsenic to the mixed iron [Fe(II)/(III)] oxide magnetite and the effect that environmental parameters, such as pH, ionic strength, and temperature, have on adsorption. Magnetite nanoparticles are unique because of their affinity for both arsenate and arsenite and increased adsorption capacity from their bulk counterparts. This article shows the effect of various magnetite nanoparticle concentrations on arsenic adsorption kinetics. The adsorption data show the ability of the magnetite nanoparticles to remove arsenate and arsenite from solution in both synthetic and natural waters, and the data fit a first-order rate equation. Because of the increased surface area of these particles, less than 1 g/L of magnetite nanoparticles was needed. The results suggest that arsenic adsorption to the nanoparticles was not significantly affected by the pH, ionic strength and temperature in the ranges tested, which are typical of most potable water sources.
162 citations
TL;DR: A new extraction technique now permits ultrafine magnetite crystals to be separated from a variety of deep-sea sediments as mentioned in this paper, revealing the presence of several distinct crystal types, some of which closely resemble those formed by the magnetotactic bacteria.
Abstract: A new extraction technique now permits ultrafine magnetite crystals to be separated from a variety of deep-sea sediments. Morphologic characterization of these particles with transmission electron microscopy reveals the presence of several distinct crystal types, some of which closely resemble those formed by the magnetotactic bacteria. The apparently biogenic magnetite particles are of single-domain size and dominate the population in calcareous deep-sea sediments. Bacterially precipitated magnetite may therefore be a major source of the stable magnetic remanence in some marine sediments. These objects possibly constitute the smallest mineral fossils yet recovered from the sedimentary record.
161 citations
TL;DR: In this article, the sonication of aqueous iron(II)acetate in the presence of β-cyclodextrin was used to produce magnetite nanorods.
Abstract: Magnetite nanorods have been prepared by the sonication of aqueous iron(II)acetate in the presence of β-cyclodextrin. The properties of the magnetite nanorods were characterized by x-ray diffraction, Mossbauer spectroscopy, transmission electron microscopy, thermogravimetric analysis, and magnetization measurements. The as-prepared magnetite nanorods are ferromagnetic and their magnetization at room temperature is ∼78 emu/g. The particle sizes measured from transmission electron micrographs are about 48/14 nm (L/W). A mechanism for the sonochemical formation of magnetite nanorods is discussed.
161 citations
TL;DR: This work is the first to indicate that both particle size and aggregation state must be considered when evaluating the reactivity of nanoparticle suspensions with groundwater contaminants, thus implicating aggregate size as an important variable.
Abstract: Nanoparticulate magnetite is found in many natural and engineered environments. This study characterized the reactivity of this material toward carbon tetrachloride (CCl4). Particle diameter plays an important role, with nominal (9 nm) magnetite suspensions exhibiting greater reactivity on both mass (k(m)) and surface area normalized (k(SA)) bases than (80 nm) magnetite suspensions. For the (9 nm) suspension, the aggregation state of the particles affects the measured km values. At 0.001 M ionic strength and pH 7, k(m) (=0.052-0.139 L g(-1) h(-1)) was as much as seven times larger than at 1 M (k(m) = 0.025-0.030 L g(-1) h(-1)). This decrease in reactivity with an increase in ionic strength is related to the measured diameter of the aggregates present in solution, thus implicating aggregate size as an important variable. This work is the first to indicate that both particle size and aggregation state must be considered when evaluating the reactivity of nanoparticle suspensions with groundwater contaminants.
160 citations