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 x 10-10 to 2.5 +/- 0.5 x 10-10 and 2.8 +/- 0.5 x 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) delta-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.