Provided is a method for synthesizing TiO.sub.2 nanocrystal, comprising: adjusting the pH value of a colloidal suspension of tetratitanic acid nanosheet as a precursor to 5-13; and subjecting the precursor to a hydrothermal reaction to obtain the TiO.sub.2 nanocrystal. The TiO.sub.2 nanocrystal synthesized by the method is anatase-type, and the exposed crystal facet thereof is {010} crystal facet. The method has advantages of low cost, no pollution, simple synthesizing process, strong controllability, short production period and good reproducibility, and is suitable for industrial production.

Provided is a method for synthesizing TiO.sub.2 nanocrystal, comprising: adjusting the pH value of a colloidal suspension of tetratitanic acid nanosheet as a precursor to 5-13; and subjecting the precursor to a hydrothermal reaction to obtain the TiO.sub.2 nanocrystal. The TiO.sub.2 nanocrystal synthesized by the method is anatase-type, and the exposed crystal facet thereof is {010} crystal facet. The method has advantages of low cost, no pollution, simple synthesizing process, strong controllability, short production period and good reproducibility, and is suitable for industrial production.

According to an embodiment of the present invention, a method for preparing a graphite-titanium oxide composite comprises (S1) a surface-modifying graphite with benzyl alcohol or a cellulose-based material using a sol-gel method, (S2) distributing the surface-modified graphite in a solvent, adding a titanium precursor to the solvent, and mixing the titanium precursor with the surface-modified graphite to obtain a graphite-titanium mixture, and (S3) thermally treating the graphite-titanium mixture to grow a titanium oxide on a surface of the graphite.

According to an embodiment of the present invention, a method for preparing a graphite-titanium oxide composite comprises (S1) a surface-modifying graphite with benzyl alcohol or a cellulose-based material using a sol-gel method, (S2) distributing the surface-modified graphite in a solvent, adding a titanium precursor to the solvent, and mixing the titanium precursor with the surface-modified graphite to obtain a graphite-titanium mixture, and (S3) thermally treating the graphite-titanium mixture to grow a titanium oxide on a surface of the graphite.

A method of recovering magnetite from bauxite residue, comprising reducing the pH of the bauxite residue to form a treated bauxite residue, drying the treated bauxite residue, adding to and mixing into the treated bauxite residue a solid source of carbon, to create a mixture, heating the mixture to a reduction temperature of at least 800° C. in a reducing reactor to produce a reduced bauxite residue in which a major portion of Fe.sub.2O.sub.3 present in the treated bauxite residue has been converted to Fe.sub.3O.sub.4, exposing the reduced bauxite residue to a particle separation step, and then separating the reduced bauxite residue into an iron-enriched portion and an iron-depleted portion.

Titanium dioxide and an electro-conductive titanium oxide which each includes particles having a large major-axis length in a large proportion and comprises columnar particles having a satisfactory particle size distribution. A titanium compound, an alkali metal compound, and an oxyphosphorus compound are heated/fired in the presence of titanium dioxide nucleus crystals having an aspect ratio of 2 or higher to grow the titanium dioxide nucleus crystals. Subsequently, a titanium compound, an alkali metal compound, and an oxyphosphorus compound are further added and heated/fired in the presence of the grown titanium dioxide nucleus crystals. Thus, titanium dioxide is produced which comprises columnar particles having a weight-average major-axis length of 7.0-15.0 μm and in which particles having a major-axis length of 10 μm or longer account for 15 wt. % or more of all the particles. A solution of a tin compound and a solution of compounds of antimony, phosphorus, etc. are added to a suspension obtained by suspending the titanium dioxide. The particles are sedimented. Subsequently, the product obtained is heated/fired to produce an electro-conductive titanium oxide which comprises the titanium dioxide and an electro-conductive coating formed on the surface thereof.

Titanium dioxide and an electro-conductive titanium oxide which each includes particles having a large major-axis length in a large proportion and comprises columnar particles having a satisfactory particle size distribution. A titanium compound, an alkali metal compound, and an oxyphosphorus compound are heated/fired in the presence of titanium dioxide nucleus crystals having an aspect ratio of 2 or higher to grow the titanium dioxide nucleus crystals. Subsequently, a titanium compound, an alkali metal compound, and an oxyphosphorus compound are further added and heated/fired in the presence of the grown titanium dioxide nucleus crystals. Thus, titanium dioxide is produced which comprises columnar particles having a weight-average major-axis length of 7.0-15.0 μm and in which particles having a major-axis length of 10 μm or longer account for 15 wt. % or more of all the particles. A solution of a tin compound and a solution of compounds of antimony, phosphorus, etc. are added to a suspension obtained by suspending the titanium dioxide. The particles are sedimented. Subsequently, the product obtained is heated/fired to produce an electro-conductive titanium oxide which comprises the titanium dioxide and an electro-conductive coating formed on the surface thereof.

The present invention disclosed use of lactam as a solvent in the preparation of nanomaterials by precipitation method, sol-gel method or high temperature pyrolysis. These methods are able to recycle lactam solvent, which meet requirements of environmental protection.

The present invention disclosed use of lactam as a solvent in the preparation of nanomaterials by precipitation method, sol-gel method or high temperature pyrolysis. These methods are able to recycle lactam solvent, which meet requirements of environmental protection.

Titanium dioxide (TiO2) forms the basis of devices for applications including sensing devices, solar cells, photo-electrochromics, and photocatalysis. Such devices exploit different phases of TiO2 within such devices and accordingly it would be beneficial to have an amorphous TiO2 precursor which allows crystalline phase spatial patterning, for the crystallization of the amorphous TiO2 precursor to be triggered at low energies, and with the crystalline phase controllable at room-temperature without necessitating complex handling whilst providing TiO2 phases that ate stable over a prolonged period of time. Accordingly, there ate provided processes for providing a TiO2 precursor and controlling the conversion of the TiO2 precursor from amorphous-to-anatase, amorphous-to-rutile, amorphous-to-mixture of anatase/rutile or from amorphous-to-anatase-to-rutile in a simple and efficient manner.