Hydrothermal synthesis of ZnO nanoparticles from recycled ZnO obtained from electric arc furnace dust: morphology control and applications

This study presents a sustainable, value-added approach to synthesizing high-quality zinc oxide nanoparticles (ZnO NPs) by utilizing ZnO recovered from industrial electric arc furnace dust (EAFD) waste. The integrated two-stage process involved selective acid leaching for precursor purification, followed by hydrothermal synthesis for morphology control. Optimized leaching using 2 M H 2 SO 4 achieved a high zinc recovery rate of over 90% while effectively minimizing lead contamination. Subsequently, key hydrothermal parameters—including pH (7–12), temperature 100–200 °C, reaction time (1–24 h), and NaOH concentration (0.5–6 M)—were systematically varied. This optimization successfully produced ZnO NPs with diverse, tunable morphologies, including nanorods, nanoplates, and nanogranules. XRD confirmed the high crystallinity and phase purity (wurtzite structure), and UV-Visible spectroscopy showed a strong UV absorption with a calculated band gap of 3.34 eV. The antibacterial activity revealed that the nanoplate morphology produced a larger inhibition zone than the nanorod against both Staphylococcus aureus and Escherichia coli. These findings demonstrate the viability of upcycling industrial waste into high-performance, morphology-controlled nanomaterials, paving the way for sustainable and environmentally friendly production.