Abstract

A simple method has been developed for the preconcentration of Mercury(II) [Hg(II)] based on the adsorption of its histidine functionalized multi-walled carbon nanotubes (MWCNTs-His) complex. The stability of a chemically MWCNTs-His were determined especially in concentrated hydrochloric acid which was then used as a recycling and pre-concentration reagent for further uses of MWCNTs-His. The application of this MWCNTs-His for adsorption of a series of metal ions was performed by using different controlling factors such as the pH of metal ion solution and the equilibration shaking time by the static technique. Hg(II) was found to exhibit the highest affinity towards extraction by these  MWCNTs-His phases. The pronounced selectivity was also confirmed from the determined distribution coefficient (Kd) of all the metal ions, showing the highest value reported for Hg(II) to occur by MWCNTs-His. The potential applications of MWCNTs-His for selective extraction of Hg(II) to occur from aqueous solution were successfully accomplished as well as pre-concentration of low concentration of Hg(II) (40 pg ml-1) from natural tap water and milk sample with a pre-concentration factor of 200 for Hg(II) off-line analysis by cold vapor atomic absorption analysis. The pre-concentration factor attainable for quantitative recovery (>96%) of Hg(II) was 100 for a 1000 ml sample volume.

Key words: Pre-concentration, Mercury(II), histidine functionalized multi-walled carbon nanotubes (MWCNTs-His).