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Synthesis and Characterization of an Eco-Friendly Magnetic Nanopowder from Steel Industry Waste for Latent Fingerprint Detection

Barbara Dias Castro, Ramana Ramalho, Jessica Milagre, Bruno Silva, Rubem Sommer, Daniel Souza, Samuel Silva, Edson Nossol, Rafael Dornellas, Fernanda Feiteira, Wagner Pacheco

Abstract

The steel industry produces large volumes of waste rich in iron oxides, creating environmental and economic challenges. In this study, we report the synthesis of an eco-friendly magnetic nanopowder derived from steel industry residue for latent fingerprint detection. The powder was prepared through a simple precipitation method and characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and vibrating sample magnetometry (VSM). The synthesized powder exhibited smaller particle aggregates (~3 µm) compared to a commercial magnetic powder (~30 µm), with Fe and O as major components and minor amounts of Mn, Mg, Zn, and K inherited from the residue. VSM analysis demonstrated a strong magnetic response, supporting efficient manipulation with a magnetic brush. When applied to non-porous surfaces, the waste-derived powder provided fingerprint ridge details with quality and minutiae counts statistically equivalent to those obtained using the commercial powder. These findings demonstrate that the developed material is a cost-effective and environmentally sustainable alternative to commercial magnetic powders, offering reliable performance in forensic fingerprint visualization while promoting the valorization of industrial waste.

CH25098  Accepted 17 September 2025

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