Abstract
Magnetic materials are promising adsorbents for removing heavy metals from polluted wastewaters. Magnetite particles were prepared by electrolytic synthesis (average crystallite size 37.9±1.2 nmnm<math><mrow><mtext>nm</mtext></mrow> </math> , surface area = 17.2 m2g−1m2g-1<math> <mrow> <msup><mrow><mtext>m</mtext></mrow> <mrow><mn>2</mn></mrow> </msup> <msup><mrow><mtext>g</mtext></mrow> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> </mrow> </math> , isoelectric point = 6.3, magnetic saturation = 62 emu g-1) and used as adsorbent of heavy metals in aqueous solutions. The adsorption capacity of the magnetite was highly dependent on pH value, for Cd+2, Zn+2, Ni+2 and Cu+2 the removal performance was higher that 80% at pH = 8. For Cr+6, the acid pH showed removal percentage higher that 90%. The adsorbent was separated from the system, reactivated and reused in subsequent tests using batch adsorption. It was found that removal efficiencies were higher than 70% even during a third cycle of adsorption. Finally, the kinetic behavior of the adsorption of each adsorbate was described by a first-order. The range of values of qe(mg/g) and k (min-1) were 1.3166-1.6367 and 0.0377 to 0.0826 respectively.