Valorization of Spent Iron Pickling Baths into Na₂SO₄/Fe₂O₃ Nanocomposites for Sustainable Recycling

README — Dataset for "Valorization of spent iron pickling baths intoNa2SO4/Fe2O3 nanocomposite for heavy metal sensing" Description:This dataset contains the raw characterization and electrochemical datasupporting the manuscript submitted to the Journal of SustainableMetallurgy. The Na2SO4/Fe2O3 nanocomposite was synthesized byco-precipitation from a spent iron pickling bath (El Hajar plant, Algeria)and applied to the electrochemical detection of Pb(II) and Cu(II) ions. Files included: 1. XRD_Na2SO4_Fe2O3.csv   X-ray diffraction pattern of the synthesized Na2SO4/Fe2O3 nanocomposite.   Columns: 2theta (degrees), Intensity (a.u.) 2. FTIR_Na2SO4_Fe2O3.csv   Fourier-transform infrared spectrum of the Na2SO4/FeOOH and   Na2SO4/Fe2O3 compounds (4000-400 cm-1).   Columns: Wavenumber (cm-1), Transmittance (%) 3. Raman_Na2SO4_Fe2O3.csv   Raman spectrum of the synthesized nanocomposite.   Columns: Raman shift (cm-1), Intensity (a.u.) 4. SEM_images.zip   Scanning electron microscopy micrographs of the Na2SO4/Fe2O3   nanocomposite at different magnifications (x5000, x10000, x20000). 5. CV_SWV_Pb_Cu_raw_data.xlsx   Raw cyclic voltammetry (CV) and square wave voltammetry (SWV) data   for the electrochemical detection of Pb(II) and Cu(II) ions using   the modified Na2SO4/Fe2O3-glassy carbon electrode (GCE).   Sheets: CV_Pb, CV_Cu, SWV_Pb, SWV_Cu   Columns: Potential (V), Current (uA) Corresponding author: AMRANEAffiliation: Université de Batna, AlgeriaEmail: chahrazadmrane@univ-batnazRelated publication:Valorization of Spent Iron Pickling Baths into Na₂SO₄/Fe₂O₃ Nanocomposites for Sustainable Recycling, submitted to Journal of SustainableMetallurgy, 2026. License: CC-BY 4.0 Abstract The treatment of spent iron pickling baths from industrial processes poses serious environmental and economic challenges due to their corrosive and hazardous nature. This study presents an eco-friendly approach to valorize both iron and sulfuric acid from these waste solutions by converting them into a Na₂SO₄/Fe₂O₃ nanocomposite via co-precipitation. The synthesis is simple, cost-effective, and optimized for production, with the precipitation process carefully controlled at approximately pH 10 to ensure efficient iron removal. The resulting nanocomposite was characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM), confirming its structural integrity and composition. Its environmental applicability was evaluated through electrochemical detection of lead (Pb²⁺) and copper (Cu²⁺) ions in aqueous solutions using a modified Na₂SO₄/Fe₂O₃-glassy carbon electrode (GCE). Electrochemical analyses, including cyclic voltammetry (CV) and square wave voltammetry (SWV), showed clear and distinct redox peaks for both ions, demonstrating high sensitivity. This method is environmentally friendly and enables complete iron recovery while minimizing waste generation. The treated solution, containing sulfate species, may be reused in industrial rinsing operations, thereby reducing freshwater consumption and minimizing environmental risks associated with iron and acid pollution. Overall, the study highlights the potential of Na₂SO₄/Fe₂O₃ nanocomposites for sustainable industrial waste valorization and efficient heavy metal ion detection in environmental monitoring.