Nonhazardous Process for Extracting Pure Titanium Dioxide Nanorods from Geogenic Ilmenite

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Industrial titanium dioxide (TiO2) production relies on sulfate and chloride processes.
• These methods involve harsh conditions (e.g., 1000 °C) and corrosive acids, leading to high costs and environmental pollution.

Purpose of the Study:

• To develop a cost-effective and environmentally friendly closed process for TiO2 synthesis.
• To produce TiO2 nanostructures with tunable crystalline phases and properties.

Main Methods:

• Ilmenite treatment using a closed process: rotatory autoclaving, refluxing, and stationary solvothermal treatment below 170 °C.
• Calcination of the synthesized amorphous TiO2 at 350 °C and 650 °C to obtain anatase and rutile phases, respectively.

Main Results:

• The developed process yields 100% pure amorphous TiO2 nanorods with flowerlike morphology (24% crystallinity).
• Calcination at 350 °C produces over 99% pure anatase TiO2 (90% crystallinity).
• Calcination at 650 °C yields 100% pure rutile TiO2 nanorods (98% crystallinity).
• Direct band gaps were determined as 3.40 eV (amorphous), 3.60 eV (anatase), and 3.15 eV (rutile).

Conclusions:

• The closed solvothermal method provides a sustainable and efficient route for TiO2 production.
• The process allows for the controlled synthesis of different TiO2 crystalline phases with distinct nanostructures.
• The tunable band gaps of the synthesized TiO2 materials suggest potential applications in various fields.