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In this article, we are discussing the synthesis and characterization of poly(vinyl alcohol)-based multiwalled carbon nanotubes (MWCNT) hydrogels and its evaluation studies for toxic metal ion removal. The functionalized MWCNT serves the purpose of toxic ion adsorbent and PVA is functioning as the substrate for the stable dispersion of MWCNT. We have carried out the evaluation studies using lead ions Pb(II) in batch experimental mode. The percentage removal of Pb(II) was examined by varying experimental conditions viz. dosage of adsorbent, pH of the solutions, and contact time. It was found that 80% removal was achieved under optimal conditions. This adsorption potential is found to be far better than that of simply dispersing MWCNT in water. The equilibrium adsorption follows the Freundlich adsorption isotherm model. After Pb(II) adsorption, the ions were easily desorbed using a high pH solution, completely regenerating for further removal process. This novel approach of dispersing MWCNT in hydrogel and their re-use after desorption is expected to have promising outcome in the water purification application. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

This paper deals with the amide functionalization of multiwalled carbon nanotubes (MWNTs) and its evaluation for mercury removal from water. The functionalized MWNTs were characterized using FTIR for structural modification. The properties of MWNTs such as hydrophilic character, nature of surface, selective chemical interaction with mercury, etc., were significantly improved after functionalization making them promising adsorbents for mercury removal. The equilibrium is achieved in short time of 5 h resulting in up to 80% removal of Hg(II). Kinetics of adsorption was established and found to follow first-order reversible kinetics with forward and backward reaction rate constants 0.6648 and 0.1662, respectively. [ABSTRACT FROM AUTHOR]