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

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.