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  • Removal of Mn(II) from aqueous solution using zeolite A : mechanism and kinetics
    Jovanovic, Mina ...
    Manganese is quite abundant metal in the Earth crust and its presence in groundwater from leaching processes varies widely depending on rock types. Also, manganese has a variety of applications such ... as in metallurgical processes, manufacture mining, ceramics, which can all be the underground pollution sources. However, sorption of the manganese(II) ions by various available sorbents has been relatively scarcely studied. In this work we have experimentally investigated sorption mechanism and kinetics of Mn(II) removal from aqueous solutions using granulated beads of zeolite A (Silkem d.o.o.) with mean diameter d=721+-80 nm taking into account possible use of this material in a fluidized bed reactor. The batch experiments were performed in the temperature range from 25 to 45 °C with initial concentrations being 100-300 mg Mn(II) dm-3. Excellent agreements of intra-particle diffusion model predictions with experimental data were obtained, which indicates that the sorption is controlled by pore-diffusion. The sorption mechanism also involves a chemical cation-exchange between the Na+ ions inside zeolite A and Mn2+ ions present in solution which was approved by elemental analyses of both solution and solid phase. XRPD analysis showed thatthe presence of Mn(II) ions did not influence the zeolite structure. Moreover, release of Mn(II) from the Mncontaining zeolite A could not be done, which indicates a strong interaction of manganese with the zeolite lattice. In order to get an insight in Mn binding, X-ray Photoelectron Spectroscopy (XPS) of Mn-containing zeolite A was performed. The Mn depth profile showed a nearly constant Mn concentration through the entire analyzed depth, suggesting that the manganese ions are uniformly distributed. However, binding energies of two peaks Mn 2p3/2 (641.5 eV) and Mn 2p1/2 (643.4 eV) indicate presence of manganese oxide particles on the zeolite surface. Since the energy region (641.0 - 642.0 eV) corresponds to different manganese oxides (1) of which the Mn(IV) oxide is the most stable, the obtained results suggests that the ion-exchange reaction is followed by an oxidation of Mn(II) to Mn(IV) oxide species.
    Vir: Book of abstracts (Str. 97)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2012
    Jezik - angleški
    COBISS.SI-ID - 5118234

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