Phosphate Removal from Aqueous Solution by Electric Arc Furnace Dust as High-Performance and Cost-Effective Adsorbent

Abstract

This study explores the processing of Electric Arc Furnace Dust (EAFD), a hazardous steelmaking by-product, for the efficient adsorption of phosphate ions from agricultural wastewater. To detoxify EAFD and enhance its adsorption performance, three washing methods hot water, alkaline NaOH, and acetic acid leaching were compared, with acetic acid proving the most effective in removing heavy metals such as lead. Comprehensive characterizations including X-ray diffraction (XRD), X-ray fluorescence (XRF), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), vibrating sample manetometer (VSM) and elemental concentration analysis by inductively coupled plasma mass spectrometry (ICP-MS) confirmed the formation of favorable surface functional groups, nanoscale particle size (∼233 nm), and magnetic properties facilitating easy separation. Adsorption experiments were conducted under varying pH, temperature, adsorbent dosage, and contact time, achieving a maximum phosphate removal efficiency of ∼ 90 % from 500 mg/L solutions at pH 2. The adsorption mechanism was attributed to electrostatic interactions between phosphate ions and positively charged sites on the EAFD surface. Thermodynamic analysis revealed that the process was spontaneous and endothermic, while kinetic modeling indicated a good fit with Langmuir and Freundlich isotherms (R² > 0.99). After adsorption, SEM-EDS and FTIR analyses confirmed phosphate capture and surface modifications. These results demonstrate that processed EAFD, due to its magnetic recyclability, low cost, and high adsorption capacity, can serve as an effective and sustainable adsorbent for phosphate removal, offering a promising solution for wastewater treatment and valorization of industrial waste.