Producing Co.sub.xFe.sub.100-x, where x is an integer from 20 to 95, nanoparticles by: (a) providing a first aqueous hydroxide solution; (b) preparing a second aqueous solution containing iron ions and cobalt ions; and (c) depositing measured volumes of the second aqueous solution into the first aqueous solution whereby coprecipitation yields CoFe alloy nanoparticles, wherein step (c) occurs in an essentially oxygen-free environment. The nanoparticles are annealed at ambient temperatures to yield soft nanoparticles with targeted particle size, saturation magnetization and coercivity. The chemical composition, crystal structure and homogeneity are controlled at the atomic level. The CoFe magnetic nanoparticles have M.sub.s of 200-235 emu/g, (H.sub.c) coercivity of 18 to 36 O.sub.e and size range of 5-40 nm. The high magnetic moment CoFe nanoparticles can be employed in drug delivery, superior contrast agents for highly sensitive magnetic resonance imaging, magnetic immunoassay, magnetic labeling, waste water treatment, and magnetic separation.

The present invention relates to a method of purifying waste hydrochloric acid, and more particularly, to a method of purifying waste hydrochloric acid which includes preparing an extraction solution by dissolving an extractant in an organic solvent (S1), extracting metallic components with the organic solvent by adding the extraction solution to the waste hydrochloric acid (S2), separating a waste hydrochloric acid layer and the organic solvent containing the metallic components (S3), and obtaining purified hydrochloric acid by recovering the separated (fractionated) waste hydrochloric acid layer (S4), wherein the extractant is used in an amount of 40 moles or more based on 1 mole of iron (Fe) included in the waste hydrochloric acid, and the waste hydrochloric acid and the extraction solution are mixed in a volume ratio of 1:0.1 to 1:1.

The present invention provides a process that allows the oxidation of trivalent arsenic and ferrous ion, simultaneous with neutralization of the acid solution to be treated, the precipitation of arsenic and oxidized ferric iron added in a molar ratio Fe:As determined at a defined pH, all of the above with a high efficiency of precipitation of arsenic as ferric arsenate or scorodite, obtaining a final residue stable in the long term, characterized by their higher content of arsenic in a lower volume compared with the procedures described in the state of the prior art.

A method of preparing magnetite particles may include providing a first solution of substantially ferrous sulphate. The first solution may be converted by replacing sulphate ions with chloride ions to produce a second solution of substantially ferrous chloride. The second solution may be oxidized to produce a third solution of substantially iron oxide. A system for purifying a solution of substantially iron oxide may include a solution reservoir, at least one membrane unit, and at least one pump for circulating the solution between the solution reservoir and the membrane unit. The solution may be delivered from the solution reservoir to an inlet of the membrane unit, and/or the solution may be returned from an outlet of the membrane unit to the solution reservoir.

A method for preparing an aqueous dispersion of metal oxide particles is disclosed. The method comprises the step of performing phase transfer of a plurality of metal oxide particles capped with hydrophobic ligands on a surface there of by contacting the metal oxide particles with a combination of tertiary amine and water to form a biphasic mixture, and agitating said biphasic mixture to produce an aqueous dispersion of metal oxide particles capped with hydrophobic ligands and tertiary amine ligands on the surface thereof.

A method for chemical processing of sewage sludge ash comprises dissolving a start material, emanating from sewage sludge ash, in an acid comprising hydrochloric acid. The start material comprising at least silicon and iron compounds. Undissolved residues are separated, whereby a leachate remains. The amount of colloidal silica in the dissolved sewage sludge ash is controlled. At least one of iron and phosphorus is extracted from the leachate by liquid-liquid extraction with an organic solvent. At least a part of a raffinate at least partly depleted in at least one of iron and phosphorus originating from the step of extracting at least one of iron and phosphorus is recirculated for dissolving the start material, emanating from sewage sludge ash. The recirculated part of the raffinate at least partly depleted in at least one of iron and phosphorus comprises chloride ions.

According to one embodiment, an active material is provided. The active material includes a lithium niobium composite oxide represented by a general formula Li.sub.xFe.sub.1yM1.sub.yNb.sub.112M2.sub.zO.sub.29 (1) and having an orthorhombic crystal structure. In the general formula (1), 0x23, 0y1 and 0<z6 are satisfied. Each of M1 and M2 independently includes at least one element selected from a group consisting of Fe, Mg, Al, Cu, Mn, Co, Ni, Zn, Sn, Ti, Ta, V, and Mo.

The present invention relates to a method for directly synthesizing titanium dioxide from a titanium-rich organic phase prepared from ilmenite, and more particularly to a method in which a titanium-rich acidolysis solution is obtained by an efficient ore dissolving technology, titanium ions are transferred to the organic phase by means of an effective titanium extractant to obtain a high-purity and titanium-rich organic phase, and then the titanium dioxide is directly synthesized in the organic phase. With this method, the dissolution rate of ilmenite can be effectively improved, the process flow is shortened and production costs are reduced, and titanium dioxide with high yield and high quality is obtained.

The present invention relates to a method for directly synthesizing titanium dioxide from a titanium-rich organic phase prepared from ilmenite, and more particularly to a method in which a titanium-rich acidolysis solution is obtained by an efficient ore dissolving technology, titanium ions are transferred to the organic phase by means of an effective titanium extractant to obtain a high-purity and titanium-rich organic phase, and then the titanium dioxide is directly synthesized in the organic phase. With this method, the dissolution rate of ilmenite can be effectively improved, the process flow is shortened and production costs are reduced, and titanium dioxide with high yield and high quality is obtained.

A method of preparing magnetite particles may include providing a first solution of substantially ferrous sulphate. The first solution may be converted by replacing sulphate ions with chloride ions to produce a second solution of substantially ferrous chloride. The second solution may be oxidized to produce a third solution of substantially iron oxide. A system for purifying a solution of substantially iron oxide may include a solution reservoir, at least one membrane unit, and at least one pump for circulating the solution between the solution reservoir and the membrane unit. The solution may be delivered from the solution reservoir to an inlet of the membrane unit, and/or the solution may be returned from an outlet of the membrane unit to the solution reservoir.