Removal of manganese in batch and fluidized bed systems using beads of zeolite a as adsorbent
In this study the uptake capacity of Mn(II) ions by zeolite A beads was investigated for different initial Mn concentration (100e400 mg Mn dm^-3) in batch mode at 25e55 C. The obtained adsorption capacity varying from 30 to 50 mg Mn g^-1 demonstrated a high affinity of zeolite A towards Mn(II) present in solutions. Kinetic studies indicated the intra-particle diffusion as the rate limiting step up to 45 C with apparent diffusivities in the range (1.2e2.0) x 10^-13 m2 s^-1 and the activation energy of 21.9 kJ mol^-1, which implies strong interactions between the zeolite A and Mn ions. At 55 C ion-exchange became the rate limiting step. The adsorption isotherms were studied at 25 C showing that the Mn adsorption is the best described by the Langmuir model suggesting a homogenous zeolite surface. XPS analysis of the Mnloaded beads showed that there is no surface accumulation of Mn but an almost uniform Mn distribution inside zeolite A, whereas XANES and EXAFS suggested that the adsorption of Mn(II) was followed by the Mn(II) oxidation and oxide formation. Regeneration of the spent zeolite was examined in 8 adsorption/desorption cycles by a chelating Na2EDTA in a fluidized column. It has been found that zeolite A beads could be reused for at least 4 cycles with satisfactory Mn(II) adsorption efficiencies of about 70%.
2016
2016-04-01 08:40:01
1033
r6
Mina
Jovanovic
70
Iztok
Arčon
70
Janez
Kovač
70
Nataša
Novak Tušar
70
Bojana
Obradovic
70
Nevenka
Rajić
70
COBISS_ID
3
4183803
DOI
15
10.1016/j.micromeso.2016.02.026
NUK URN
18
URN:SI:UNG:REP:DW6W3VOA
NevenkaRajic-MicroporousMesoporousMaterials-2016_reprint.pdf
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