Starch Films Reinforced with Amazonian Manganese Ore Residues: Mechanical, Water Vapor Barrier, and UV-Shielding Performance

Mining waste-derived reinforcing materials represent a sustainable strategy for enhancing the performance of packaging composites. Incorporating mining tailings and low-end nanomaterials synthesized from these residues into polymer-based films combines low-cost manufacturing with circular economy principles. In this study, manganese ore beneficiation waste and two manganese-based compounds synthesized from the same tailings, namely, manganese ore tailings (RBK), BaMnO₄, and MnO₂, were evaluated as reinforcing agents in casting starch films suitable for packaging applications (e.g., shopping bags). These materials were incorporated at concentrations ranging from 0.25 to 1% (w w^-1). The addition of RBK and BaMnO₄ significantly reduced the water vapor permeability (WVP) of the starch films from 4.9 ± 0.9 × 10^-10 to 2.5 ± 0.5 × 10^-10 and 2.8 ± 0.5 × 10^-10 kg m^-1 s^-1 Pa^-1, respectively. BaMnO₄ also notably enhanced tensile strength, increasing it from 3.5 ± 0.2 to 20 ± 4 MPa, regardless of concentration. Additionally, 1% (w w^-1) δ-MnO₂ produced broad near-UV/visible attenuation, whereas RBK and BaMnO₄ primarily strengthened the UVB barrier, these changes being accomplished with a higher opacity (600 nm). Overall, the incorporation of manganese-based materials derived directly from manganese ore beneficiation residues shows strong potential for improving the functional properties of starch films, enabling the development of low-cost, value-added, and environmentally responsible packaging materials. Furthermore, the reuse of mining waste contributes to mitigating the environmental impact associated with tailings storage.