Removal of Ni(II), Cu(II), Pb(II), and Cd(II) from\nAqueous Phases by Silver Nanoparticles and Magnetic Nanoparticles/Nanocomposites

Abstract

The intake of heavy\nmetals into the body, even at very low concentrations,\nmay cause a decrease in central nervous system functions; deterioration\nof blood composition; and liver, kidney, and lung damage. Therefore,\nheavy metal ions must be removed from water. In this study, silver,\nmagnetic iron/copper, and iron oxide nanoparticles were synthesized\nusing Lathyrus brachypterus extract\nand then Fe/Cu-AT, Fe₃O₄-AT, Fe/Cu-CS, and Fe₃O₄–CS magnetic nanocomposite beads were\nsynthesized using alginate and chitosan. The removal of Cd(II), Pb(II),\nNi(II), and Cu(II) ions from aqueous phases using synthesized nanoadsorbents\nwas investigated by single and competitive (double and quaternary)\nadsorption techniques. The kinetic usability of the magnetic iron\noxide chitosan (Fe₃O₄–CS) nanocomposite\nbeads with the highest removal efficiency was evaluated. Based on\nexperimental results, the order of removal was found to be 98.39,\n75.52, 51.54, and 45.34%, and it was listed as Pb(II) > Cu(II)\n> Cd(II)\n> Ni(II), respectively. The Dubinin–Radushkevich, Freundlich,\nLangmuir, and Temkin isotherm models were used, and experimental results\nrevealed that the experimental data fit the Langmuir model better.\nThe maximum adsorption capacities (<i>q</i>_m)\nobtained from the Langmuir isotherm model of Fe₃O₄–CS were found to be 8.71, 23.75, 18.57, and 12.38 mg/g for\nNi(II), Pb(II), Cu(II), and Cd(II) ions, respectively. When the kinetic\ndata were applied to the Lagergren, Ho–McKay, and Elovich models,\nit was observed that the adsorption kinetics mostly conformed to the\nHo–McKay second-order rate equation. The binary and quaternary\ncompetitive adsorption data showed that Fe₃O₄–CS were selective toward Cu(II) and Pb(II). The reusability\nof the Fe₃O₄–CS nanoadsorbent was performed\nas three cycles with the same concentration. The adsorption capacities\nwere found to be 95.81, 70.65, 50.50, and 42.75%, in turn for Pb(II),\nCu(II), Cd(II), and Ni(II) ions after three cycles, which revealed\nthat the Fe₃O₄–CS nanoadsorbent can be\nused after three cycles without losing its efficiency.