| Summary: | Polyvinyl alcohol/chitosan (PVA/chitosan) and Polyvinyl alcohol/chitosan
composite beads containing MgAl layered double hydroxide (PVA/MgAlLDH/chitosan) were synthesized for the adsorption of chrome hexavalen. The
composites were characterized with Fourier transform infrared spectroscopy
(FTIR), X-Ray Diffraction (XRD) and scanning electron microscopy � energy
dispersive X-ray analysis (SEM-EDAX). Effect of pH, MgAl-LDH content in
composites, contact time, initial concentration of HCrO4
-and sulphate competitor
have been investigated on this research. Results showed that blending of PVA
with chitosan and LDH-chitosan beads significantly improved their stability in the
adsorption medium. Fifty percent deformation for MgAl-LDH/chitosan beads
without PVA content decreased to 0% with PVA content (PVA/chitosan = 1:1
mass ratio). Adsorption of HCrO4
-on PVA/chitosan and PVA/MgAlLDH/chitosan was optimum at pH 4 (1 : 0.25 mass ratio of chitosan/MgAl-LDH).
The adsorption of HCrO4
-reached equilibrium at 90 min. Adsorption HCrO4
-on
both composite followed Ho pseudo second order kinetic and the adsorption
equilibrium followed Langmuir isotherm model. The adsorption capacities of
PVA/chitosan and PVA/MgAl-LDH/chitosan were 3.6 mg/g and 4.4 mg/g,
respectively. The increased of sulphate in HCrO4
-solution decreased adsorption of
HCrO4
-up to 38.7% on PVA/chitosan and 36.3% on PVA/MgAl-LDH/chitosan at
mol ratio [HCrO4
-/[SO
4
2-]=1-100. Decrease of adsorption HCrO4
-on both
composites caused of competition with sulphate.
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