Provided is an iron oxide powder for a brake friction material which can be suitably used in a brake friction material that is less likely to cause problems regarding brake squealing and that provides superior braking performance. The iron oxide powder for a brake friction material according to a first embodiment of the present invention is characterized by having a sulfur content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less. The iron oxide powder for a brake friction material according to a second embodiment of the present invention is characterized by having an average particle size of 1.0 μm or more, a chlorine content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less.

The present invention is related to effect pigments exhibiting a deep black body color as well as a blue interference color, to a process for the production of such pigments as well as to the use thereof, especially in coating compositions.

The present invention is related to effect pigments exhibiting a deep black body color as well as a blue interference color, to a process for the production of such pigments as well as to the use thereof, especially in coating compositions.

A substituted ε-iron oxide magnetic particle powder having a reduced content of an α-type iron-based oxide and Fe sites of ε-Fe.sub.2O.sub.3 partially substituted by another metal element is obtained by neutralizing an acidic aqueous solution containing a trivalent iron ion and an ion of a metal that partially substitutes Fe sites to a pH of between 2.0 and 7.0. Thereafter, a silicon compound having a hydrolyzable group is added to a dispersion liquid containing an iron oxyhydroxide having a substituent metal element or a mixture of an iron oxyhydroxide and a hydroxide of a substituent metal element. The dispersion liquid is neutralized to a pH of 8.0 or higher and the iron oxyhydroxide having a substituent metal element or the mixture of the iron oxyhydroxide and the hydroxide of a substituent metal element is coated with a chemical reaction product of the silicon compound. The dispersion is then heated.

A substituted ε-iron oxide magnetic particle powder having a reduced content of an α-type iron-based oxide and Fe sites of ε-Fe.sub.2O.sub.3 partially substituted by another metal element is obtained by neutralizing an acidic aqueous solution containing a trivalent iron ion and an ion of a metal that partially substitutes Fe sites to a pH of between 2.0 and 7.0. Thereafter, a silicon compound having a hydrolyzable group is added to a dispersion liquid containing an iron oxyhydroxide having a substituent metal element or a mixture of an iron oxyhydroxide and a hydroxide of a substituent metal element. The dispersion liquid is neutralized to a pH of 8.0 or higher and the iron oxyhydroxide having a substituent metal element or the mixture of the iron oxyhydroxide and the hydroxide of a substituent metal element is coated with a chemical reaction product of the silicon compound. The dispersion is then heated.

The disclosure provides a method of producing a metal compound. The method comprises contacting a metal source with a reaction mixture, wherein the reaction mixture comprises an ionic liquid and an oxidising agent, and thereby producing the metal compound.

Crystalline α-Fe.sub.2O.sub.3 nanoparticles prepared by ultrasonic treatment of a solution of an iron (III)-containing precursor and an extract from the seeds of a plant in the family Linaceae. The crystalline α-Fe.sub.2O.sub.3 nanoparticles have a spherical morphology with a diameter of 100 nm to 300 nm, a mean surface area of 240 to 260 m.sup.2/g, and a type-II nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. The crystalline α-Fe.sub.2O.sub.3 nanoparticles have a band gap of 2.10 to 2.16 eV and a mean pore size of 7.25 to 9.25 nm. A method for the photocatalytic decomposition of organic pollutants using the crystalline α-Fe.sub.2O.sub.3 nanoparticles. An antibacterial composition containing the crystalline α-Fe.sub.2O.sub.3 nanoparticles.

The present invention relates to a ferrite particle, containing a crystal phase component containing a perovskite crystal represented by the compositional formula:

RZrO.sub.3 (provided that R represents an alkaline earth metal element), and having an apparent density in a range represented by the following formula:

1.90≤Y≤2.45

provided that Y in the formula is the apparent density (g/cm.sup.3) of the ferrite particle.

The present invention relates to a ferrite particle, containing a crystal phase component containing a perovskite crystal represented by the compositional formula:

RZrO.sub.3 (provided that R represents an alkaline earth metal element), and having an apparent density in a range represented by the following formula:

1.90≤Y≤2.45

provided that Y in the formula is the apparent density (g/cm.sup.3) of the ferrite particle.

The present invention discloses a method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron. The method includes: dissolving red mud in water, introducing excessive SO.sub.2, introducing O.sub.2 for aeration, and refluxing part of alkaline leachate after filtering; when pH of a red mud mixture decreases to below 3, washing and filtering the red mud mixture, adding NaOH to acidic leachate to adjust its pH to a strongly alkaline level, aging and filtering the leachate, treating filter residue to recover Fe.sub.2O.sub.3, and refluxing part of alkaline leachate after filtering to the red mud mixture; and adjusting pH of the remaining alkaline leachate after filtering to a weakly acidic level, and conducting filtering to recover aluminum.