Abstract
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Modification of MIL-100(Fe) with ethanediamine (ED) is expected to improve the removal percentage of Pb(II) ions from aqueous solution. Nevertheless, the adsorption performance of ED-MIL-100(Fe) in natural waters will be affected by natural organic matter such as fulvic acids (FA). Hence, it is necessary to study the influence of FA on the physicochemical property, adsorption behavior and mechanisms of ED-MIL-100(Fe) towards the removal of Pb(II) from water.
Batch adsorption experiments were conducted to compare adsorption capacity of MIL-100(Fe) and ED-MIL-100(Fe) for Pb(II). In addition, XRD, FTIR, SEM and XPS techniques were applied to investigate the characteristics, adsorption isotherms, and kinetics in the presence and absence of FA.
ED-MIL-100(Fe) enabled 99% removal of Pb(II) from water at or below 60 mg L−1, whereas the MIL-100(Fe) hardly adsorbed any Pb(II). Additionally, the adsorption percentage of the Pb(II) ions (76%) outcompeted that of other metal ions (i.e. Co, Cu, Ni, Zn, and Cd) (each ≤ 25%) in the mixed solution. The negative surface charge of ED-MIL-100(Fe) was not affected by FA. Increasing FA concentration steadily increased the functional groups surrounding the ED-MIL-100(Fe) via electrical interaction, thus facilitating the Pb(II) ions adsorption.