Bauxite residue recovery includes mixing a solution of hydrochloric acid (HCL) according to a predetermined concentration, and adding the HCL solution to a quantity of raw red mud recovered from industrial operations as waste material. The highly alkaline property of the bauxite residue, commonly known as red mud is at least partially neutralized from the HCL, and makes the resulting washed red mud more amenable to subsequent uses in various applications in fields such as construction, wastewater treatment, and metal recovery processes. The process recovers washed red mud from the red mud and HCL solution by filtering the raw red mud and HCL solution for generating a stream of leach liquor from the filtrate and the recovered washed red mud from the residue. The neutralized red mud is further treated to extract metals such as calcium, iron, aluminum, silicon, and titanium.

Methods are disclosed for dispersing nanoparticles in solvents, involving the use of a cationic species and an anionic species, where at least one of the ionic species is soluble in the nonpolar solvent and the other ionic species has a relatively strong affinity for the surface of the nanoparticles. The cationic species and the anionic species together form a cluster of ion pairs shielding the nanoparticles and enhancing their dispersibility in the nonpolar solvent.

Methods are disclosed for dispersing nanoparticles in solvents, involving the use of a cationic species and an anionic species, where at least one of the ionic species is soluble in the nonpolar solvent and the other ionic species has a relatively strong affinity for the surface of the nanoparticles. The cationic species and the anionic species together form a cluster of ion pairs shielding the nanoparticles and enhancing their dispersibility in the nonpolar solvent.

A core-shell particle includes: a core including an iron oxyhydroxide compound represented by Formula A.sup.3.sub.a3Fe.sub.1−a3OOH (in which A.sup.3 represents at least one metal element other than Fe, and a3 satisfies 0<a3<1) or at least one iron oxide compound selected from the group consisting of Fe.sub.2O.sub.3, a compound represented by Formula A.sup.1.sub.a1Fe.sub.2−a1O.sub.3 (in which A.sup.1 represents at least one metal element other than Fe, and a1 satisfies 0<a1<2), Fe.sub.3O.sub.4, and a compound represented by Formula A.sup.2.sub.a2Fe.sub.3−a2O.sub.4 (in which A.sup.2 represents at least one metal element other than Fe, and a2 satisfies 0<a2<2); and a shell which covers the core and includes a polycondensate of a metal alkoxide.

A core-shell particle includes: a core including an iron oxyhydroxide compound represented by Formula A.sup.3.sub.a3Fe.sub.1−a3OOH (in which A.sup.3 represents at least one metal element other than Fe, and a3 satisfies 0<a3<1) or at least one iron oxide compound selected from the group consisting of Fe.sub.2O.sub.3, a compound represented by Formula A.sup.1.sub.a1Fe.sub.2−a1O.sub.3 (in which A.sup.1 represents at least one metal element other than Fe, and a1 satisfies 0<a1<2), Fe.sub.3O.sub.4, and a compound represented by Formula A.sup.2.sub.a2Fe.sub.3−a2O.sub.4 (in which A.sup.2 represents at least one metal element other than Fe, and a2 satisfies 0<a2<2); and a shell which covers the core and includes a polycondensate of a metal alkoxide.

A bi-phased approach between good solvents (or non-polar) and bad solvents (polar) can be used to assemble nanorods into highly ordered monolayers or multilayers of ordered nanorod arrays. These ordered nanorod arrays can display unique optical properties. For example, ordered arrays of CdSe/CdS core/shell nanorods were assembled that display polarized photoluminescence.

A bi-phased approach between good solvents (or non-polar) and bad solvents (polar) can be used to assemble nanorods into highly ordered monolayers or multilayers of ordered nanorod arrays. These ordered nanorod arrays can display unique optical properties. For example, ordered arrays of CdSe/CdS core/shell nanorods were assembled that display polarized photoluminescence.

The present invention relates to a method of controlling the arrangement of building block nanocrystals in iron oxide mesocrystals by controlling the type of surface ligand, the method including mixing an iron ion precursor and a surface ligand. The present invention can provide nanoparticles having different magnetic properties by controlling the crystallographic arrangement of building block nanocrystals in mesocrystals according to surface ligands.

A wavelength converter material and a method of A method of preparing a wavelength converter material may include providing an optionally oxide coated phosphor material, mixing the optionally oxide coated phosphor material with an optionally oxide coated paramagnetic nanoparticle, coating the optionally oxide coated phosphor material and the optionally oxide coated paramagnetic nanoparticle with an oxide coating, thereby preparing a coated phosphor-nanoparticle particle, and separating the coated phosphor-nanoparticle particle, thereby preparing a wavelength converter material. The separating of the coated phosphor-nanoparticle particle may be manipulated by applying a magnetic field.

Furthermore, a wavelength converter material, as well as a light emitting diode are described herein.

A wavelength converter material and a method of A method of preparing a wavelength converter material may include providing an optionally oxide coated phosphor material, mixing the optionally oxide coated phosphor material with an optionally oxide coated paramagnetic nanoparticle, coating the optionally oxide coated phosphor material and the optionally oxide coated paramagnetic nanoparticle with an oxide coating, thereby preparing a coated phosphor-nanoparticle particle, and separating the coated phosphor-nanoparticle particle, thereby preparing a wavelength converter material. The separating of the coated phosphor-nanoparticle particle may be manipulated by applying a magnetic field.

Furthermore, a wavelength converter material, as well as a light emitting diode are described herein.