One-Step Synthesis of Iron and Titanium-Based Compounds Using Black Mineral Sands and Oxalic Acid under Subcritical Water Conditions

Black mineral sands are widely used to obtain titanium dioxide, titanium, and, more recently, a variety of iron–titanium oxide nanostructures. Highly corrosive acids or alkalis commonly employed for this purpose. Hence, it is desirable find eco-friendly ways process these minerals, deriving high-added value materials. In study, an Ecuadorian sand precursor (0.6FeTiO3?0.4Fe2O3 solid solution) was treated with oxalic acid aqueous solutions under subcritical water conditions. The synthesis conducted in batch reactor operating at 155 °C, 50 bar, and 700 rpm 12 h, varying the concentration (0.1, 0.5 1.0 M). as-obtained compounds were physically separated, dried, analyzed by X-ray powder diffraction, scanning electron microscopy, Raman spectroscopy. characterization showed that completely converted into two main products, ferrous oxalate, dioxide polymorphs. Rutile always found as-synthesized while anatase only crystallized high concentrations (0.5 These results open possibility develop sustainable routes synthesize iron titanium-based materials promising applications.