| Zeolite A-MgO composite was synthesized in presence of zeolite A particles, MgCl2
and urea solution under hydrothermal reaction at 150oC for 5 h followed by calcination
at 600oC/2 h. XRD and FTIR results showed the crystallization of MgO along with NaA
zeolite crystals. Nano-sheet like MgO particles (50-70 nm) were grown onto the surface
of NaA zeolite crystals (1 m). BET surface area and pore size of the sample were
found to be 69 m2.g–1 and 3.9 nm, respectively. XPS analysis showed the binding
energies of O1s, Si2p, Na1s, Al2p and Mg2p as 531.6, 102.4, 1072.2, 74.2 and 49.9 eV,
respectively. The synthesized product (1 g.L–1 dose) showed 72% adsorption of fluoride
(7.24 mg.L–1) within 5 min and reached up to 94% for 90 min at pH 6.8. The adsorption
capacity of the sample was calculated as 107.64 mg.g–1 from Langmuir isotherm. The
sample could be regenerated up to 5th cycle. A tentative mechanism for the adsorption
of fluoride from aqueous solution by the synthesized zeolite A-MgO composite was
proposed.
[Keywords: Zeolite A-MgO composite, Crystallization, Textural properties,
Defluoridation, Kinetics model, Adsorption isotherm] |
