Simultaneous Removal of Chlorides and Calcium from EAF Dust Wastewater

This research investigates the sorption efficiencies of various adsorbents—synthesized Hydrotalcite, natural zeolite Clinoptilolite, synthetic zeolite, and waste sludge from aluminum anodic oxidation—for simultaneous removal of Cl⁻ and Ca2⁺ ions from synthetic CaCl₂ solutions and wastewater from EAFD recycling. This study addresses the challenges of wastewater purification options, which were not previously addressed in other studies. The high alkalinity and ionic pollutants in EAFD wastewater make the purification process complex. The fact that adsorbents tested in this study were prepared from metallurgical waste predetermines the process to be more sustainable. Adsorbents were thoroughly characterized before and after calcination and sorption using techniques like AAS, LIBS, XRD, BET, BJH, SEM-EDS, and FTIR spectroscopy. Synthetic zeolite achieved near-complete removal of Ca2⁺ ions, while calcined Hydrotalcite at 500 °C excelled in the simultaneous removal of Cl⁻ and Ca2⁺. Equilibrium sorption capacities of HT were 50.3 mg/g for Cl⁻ and 37 mg/g for Ca2⁺ after 360 min, with efficiencies reaching 85% for Ca2⁺ and 83% for Cl⁻. Additionally, HT effectively removed 82% Pb, 91% Cr, and 40% SO₄2⁻ in 24 h of the sorption process. These findings highlight HT as a promising solution for industrial wastewater treatment, offering sustainable and efficient pollutant removal.