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

## TL;DR

This paper explores using Amazonian manganese mining waste to reinforce starch films, improving their strength, water resistance, and UV protection for eco-friendly packaging.

## Contribution

The novel use of manganese ore residues and derived compounds as low-cost, sustainable additives for starch-based packaging films.

## Key findings

- Manganese-based compounds significantly reduced water vapor permeability of starch films.
- BaMnO4 increased tensile strength of films up to 20 MPa.
- MnO2 provided broad UV/visible light attenuation while RBK and BaMnO4 enhanced UVB protection.

## Abstract

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.