Copper flotation waste from KGHM as potential sorbent for heavy metal removal from aqueous solutions

Abstract

<p>Sorption affinity of copper flotation waste from KGHM toward Cd(II), Cr(III), Cu(II), and Pb(II) ions was investigated in this work. Batch sorption studies, using single-element synthetic aqueous solutions at various pH (2–12), contact time (10–300 min), initial concentration (100–5000 mg dm⁻³; 1–100 mg dm⁻³ for Cd(II)) and adsorbent dose (25–200 g dm⁻³), were performed. Bonding strength of adsorbed metals was tested from the degree of desorption. The maximum metal removal was observed at pH 5–8, ≥120 min reaction time, and 25 g dm⁻³ adsorbent dose. Maximum sorption capacities of studied material were 41.6, 58.8, and 83.8 mg g⁻¹ for Cr(III), Cu(II), and Pb(II), respectively, for 5000 mg dm⁻³ initial concentration, and 0.86 mg g⁻¹ for Cd(II) for initial concentration of 50 mg dm⁻³. Sorption isotherms were very well fitted to Langmuir (Cd, Cr, Pb) and Freundlich (Cu) models. Sorption kinetics was nearly ideally fitted to pseudo-second-order kinetic model. Desorption studies showed that most of Cr(III) (98.5%) and Pb(II) (67.3%) ions remained bound to the surface, indicating that the chemisorption dominated as a controlling process. On the other hand, mostly desorbed were Cd(II) (98.5%) and Cu(II) (90.3%) ions, which indicated that processes like physisorption or precipitation were prevailing.</p