The steel industry generates enormous quantities of iron oxide waste powder (IOWP) from acid regeneration of spent pickling liquor. IOWP is hazardous due to its high acidic and metal compositions, which calls for strategies to safely manage it. In this study, IOWP was utilized in synthesis of magnetite nanoparticles (Fe 3 O 4 NPs) through co-precipitation. The synthesis parameters including NaOH concentration (15–25%), reaction time (1–3 h), and temperature (50–100 °C) were optimized with central composite design of response surface methodology to yield nanoparticles of high surface area (SA). The synthesized nanoparticles were characterized by XRD, DLS, BET, VSM, FTIR, Raman spectroscopy, SEM, HRTEM, EDX, SAED, UV–vis as well as electro-transfer properties using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Spherical superparamagnetic polycrystalline Fe 3 O 4 NP with average particle size of 9 nm, and SA 207 m 2 /g were generated at 15% NaOH concentration, reaction time of 1 h, and temperature of 100 °C. The NPs were mesoporous with 10. 4 nm pore diameter, and pore volume of 0.309 cm 3 /g. They had a band gap energy of 2.6 eV, zeta potential of −16.02 mV, and a saturation magnetization of 71 emu/g. CV and EIS studies showed that coating screen printed carbon electrodes with the Fe 3 O 4 NP enhanced the peak anodic current by 33%, reduced charge transfer resistance by 16%, and registered a 65% increase in electrochemical active area. Economic analysis of large-scale production of Fe 3 O 4 NPs (50 ton/year) indicated a payback period of 1.82 years, 85.7% profit margin, and 10-year ROI of 450.9%. These characteristics show IOWP can be managed by producing nanomaterials of high quality with potential applications in pollutant adsorption, sensor modifications, photocatalysis, and biomedicine. • Magnetite nanoparticles (MNPs) were synthesized from iron oxide waste powder. • The synthesis process was optimized with response surface methodology. • Superparamagnetic MNPs were generated at 15% NaOH, in 1 h at 100 °C. • MNPs had high surface area and magnetization making them suitable for water treatment.
Jjagwe et al. (Tue,) studied this question.