Polyindole-maghemite nanocomposite for adsorption of copper (II) and chromium (VI) ions in aqueous solution
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Date
2016-06
Authors
Lim Wei Chun
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Abstract
Polyindole/maghemite (PIn/γ-Fe2O3) nanocomposite was prepared via chemical oxidative polymerization and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From TEM images, the surface morphology of PIn/γ-Fe2O3 nanocomposite appeared in core-shell structure where the polyindole encapsulate maghemite nanoparticles. PIn/γ-Fe2O3 nanocomposite was used to investigate the effect of interaction time on Cu (II) and Cr (VI) ions adsorption. The adsorption kinetics of PIn/γ-Fe2O3 nanocomposite also being studied through pseudo-first order and pseudo-second order kinetics models. The adsorption experiments are conducted using 2 mg adsorbent into 100 mg/L heavy metal solution with pH 3.5 and examined with Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Both heavy metal ions adsorption reached equilibrium after 45 minutes. The equilibrium adsorption capacity of Cu (II) (qe = 26.1 mg/L) is higher than Cr (VI) (qe = 21.8 mg/L) due to larger ionic radius (Cu (II):0.57 Å > Cr (VI): 0.26 Å) and smaller hydrated radius (Cu (II): 4.19 Å < Cr (VI): 4.61 Å). The adsorption kinetics of PIn/γ-Fe2O3 nanocomposite is best described by pseudo-first order kinetics model. This indicates that the adsorption process of PIn/γ-Fe2O3 nanocomposite on the Cu (II) and Cr (VI) ions in aqueous solution is mainly based on physical adsorption.