Cu2+, Cd2+ and Pb2+ adsorption from aqueous solutions by pyrite and synthetic iron sulphide

In this study, removal of Cu2+, Cd2+ and Pb2+ from aqueous solutions by adsorption onto pyrite and synthetic iron sulphide (SIS) was investigated as a function of pH, contact time, adsorbent dosage, initial metal concentration and temperature. It has been determined that the adsorption of metal ions onto both adsorbents is pH dependent and the adsorption capacities increase with the increasing temperature. The mechanisms governing the metal removal processes were determined as chemical precipitation at low pH (<3) due to H2S generation and adsorption at high pH (in the range of 3–6). The metal adsorption yields also increased with the increasing adsorbent dosage and contact time and reached to equilibrium for both adsorbents. The Cu2+, Cd2+ and Pb2+ adsorption capacities of both adsorbents decrease in the order of Pb2+ > Cu2+ > Cd2+. Except for cadmium, little fraction of copper and lead in the solid adsorption residues was desorbed in acidic media.