Environmental Engineering Reference
In-Depth Information
polymerization technique and studied its electrical properties. Herein, MWCNTs
were modified with PANI by using plasma induced polymerization technique to
synthesize PANI/MWCNTs magnetic composites. The prepared PANI/MWCNTs
magnetic composites were characterized by ultraviolet-visible (UV-vis) spectro-
photometer, X-ray photoelectron spectroscopy (XPS), thermo gravimetric analy-
sis-differential thermal analysis TGA-DTA), field-emission scanning electron
microscopy (FE-SEM), and vibrating sample magnetometer (VSM). The prepared
PANI/MWCNTs magnetic composites were applied to adsorb and to enrich Pb(II)
from aqueous solutions to evaluate its application in the removal of heavy metal
contaminants from large volumes of aqueous solutions in environmental pollution
cleanup. In the application of PANI/MWCNTs to remove Pb(II) ions in environ-
mental pollution management, the pH value of aqueous solutions is also crucial
because the adsorption of metal ions on solid particles is generally affected by
the pH values. Moreover, the amine and imine functional groups of PANI and the
oxygen containing functional groups of MWCNTs on PANI/MWCNT surfaces
are protonated at low pH. The functional groups of PANI/MWCNTs are proton-
ated easily at low pH, causing PANI/MWCNTs carry positive charges. Moreover,
at low pH, the functional groups on PANI/MWCNT surfaces are competitively
bound by the protons in aqueous solutions, which can restrict the enrichment of
Pb(II) onto PANI/MWCNTs. The protonation of functional groups on PANI/MW-
CNT surfaces decreases with increasing pH, which results in the less positively
charged PANI/MWCNTs. It is reasonable that the competitive binding for the
functional groups on PANI/MWCNT surfaces between protons and Pb(II) will
decrease. The removal of Pb(II) on MWCNTs and PANI/MWCNTs as a function
of pH is dependent on pH values. The effect of ionic strength on the sorption of Pb
(II) to PANI/MWCNTs is also important because of the presence of different cat-
ions and anions in the environment and the salt concentration in wastewater may
be different for different sites. PANI/MWCNT magnetic composites were synthe-
sized by using plasma induced polymerization technique. The analysis results of
UV-vis spectra, XPS, TGA, and FE-SEM characterizations indicate that PANI
has been modified onto MWCNTs. PANI/MWCNTs magnetic composites have
very high adsorption capacities in the removal of Pb(II) ions from large volumes
of aqueous solutions, and PANI/MWCNTs magnetic composites can be separated
and recovered from solution by simple magnetic separation. The results of this
research highlight the potential application of the magnetic composites of PANI/
MWCNTs for heavy metal contaminants cleanup in the natural environment.
1.1.6.9 CNT-ALGINATE COMPOSITES AS ADSORBENT
Widespread usage of CNTs will cause increasing emissions to the water environ-
ment and result in human contact risk to CNTs.Another adverse factor currently
restricting the application of CNTs to environmental protection/remediation is
their high costs. These difficulties encountered in environmental applications
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