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Iron-Modified Sepiolite for Ni 2+ Sorption from Aqueous Solution: An Equilibrium, Kinetic, and Thermodynamic Study

2010; American Chemical Society; Volume: 55; Issue: 12 Linguagem: Inglês

10.1021/je100639k

1520-5134

Slavica Lazarević, Ivona Janković‐Častvan, Veljko Djokić, Željko Radovanović, Djordje Janaćković, Rada Petrović,

Iron oxide chemistry and applications

Sepiolite was used for the synthesis of the sepiolite−iron oxide system to obtain a sorbent suitable for the removal of Ni2+ from aqueous solution. The modified material, Fe-sepiolite, was characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential thermal/thermogravimetric analysis, and point of zero charge (pHpzc) determination. The sorption experiments were performed as a function of the initial metal concentration, equilibration time, and temperature using the batch method. The Fe-sepiolite had a higher sorption capacity than the natural sepiolite sample due to a higher specific sorption and a higher ion exchange with Mg2+ ions from the sepiolite surface. Thermodynamic parameters, such as enthalpy, Gibbs energy, and entropy, were calculated from the temperature-dependent sorption isotherms, and these values showed that the sorption of Ni2+ onto sepiolites was endothermic. Pseudo-second-order kinetic models provide the best correlation of the experimental kinetic data.