The Simultaneous Removal of Chlorides and Calcium from Synthetic Solution and EAF Dust Washing Wastewater: The Study of the Suitability and Sustainability of Various Adsorbents

This work is focused on the investigation of sorption efficiencies and capacities of different adsorbents (synthesized Hydrotalcite, natural zeolite Clinoptilolite, synthetic zeolite and waste sludge from Al anodic oxidation) for simultaneous Cl- and Ca2+ removal from a synthetic solution (CaCl2) as well as from real wastewater (from EAFD recycling) for sustainable industrial wastewater purification process. The initial samples of adsorbents, as well as after the calcination and sorption process, were characterized, and it was described their chemical and phase composition (by AAS and XRD), surface area (BET analysis), porosity (BJH method) and molecule structure (FTIR). The highest efficiency (~100%) for Ca2+ removal from the synthetic solution as well as from real wastewater showed the synthetic zeolite. However, calcined Hydrotalcite at 500°C (HT-b) appeared to be the most efficient adsorbent for the simultaneous removal of Cl- and Ca2+. In this case, the maximum sorption capacity for Cl- (50.3 mg/g) and Ca2+ (42.2 mg/g) from EAFD wastewater were obtained after 360 minutes and the highest sorption efficiencies were achieved 98.9% for Ca2+ and 81% for Cl- after 24 hours. At the same time, 82% of Pb, 91% of Cr and 40 % of SO42 were removed from wastewater by HT-b.