From ilmenite to TiO2 nanostructures: integrated processing routes, phase control, and photocatalytic applications

In recent years, processing naturally occurring materials, such as ilmenite, to develop titanium dioxide nanostructures has emerged as an economic, renewable, and eco-friendly approach. This review article focuses on various processing routes of ilmenite, namely, pre-treatment, extractive processing (sulfate and chloride methods), and the synthesis of the resulting titanium dioxide nanostructures. The resulting architectures, including nanofibers, nanotubes, nanowires, and nanoparticles, demonstrate significant potential in photocatalytic applications, particularly under visible light irradiation. While there have been encouraging outcomes at laboratory scales, significant challenges remain, such as the diversity in chemical compositions of ilmenite deposits and the comparatively high energy consumption associated with conventional processing routes. Addressing these challenges requires the development of energy-efficient processing routes (100-120 °C) as an integral component of industrial scalability. Overall, utilizing ilmenite as a precursor for nanostructure synthesis holds immense potential for promoting green technologies in environmental, energy, and healthcare sectors.