Competitive removal of Cu2+, Cd2+, Zn2+, and Ni2+ ions onto iron oxide nanoparticles from wastewater

A competitive adsorption of Cu2+, Ni2+, Zn2+, and Cd2+ ions onto Fe3O4 nanomaterial was studied. Experimental parameters such as, pH, initial metal concentrations, and temperatures were investigated. The uptake capacity was 11.5, 6.07, 11.1, and 9.68 mg/g for Cu2+, Ni2+, Zn2+, and Cd2+, respectively. The optimum pH and contact time were found to be 6 and 50 min for Cu2+, Ni2+, Zn2+, and Cd2+. The equilibrium isotherm for single component system was of favorable type and Freundlich isotherm model gave the best fitting for the experimental data. Binary, ternary, and quaternary systems were conducted to find the adsorption isotherm constants for each adsorption models; combination of Langmuir–Freundlich model gave the best fit. In single, binary, ternary, and quaternary systems, Cu2+ always adsorbed more favorably onto nanosorbent than Zn2+, Cd2+, and Ni2+. The adsorption capacity parameters were: Cu2+ > Zn2+ > Cd2+> Ni2+. Thermodynamic study was carried out and the results showed that the adsorption was an endothermic process.