Adsorption of mercury(II), methyl mercury(II) and phenyl mercury(II) on chitosan cross-linked with a barbital derivative

The sorption behavior of glutaraldehyde cross-linked chitosan (G-Chitosan) and barbital-glutaraldehyde cross-linked chitosan (BG-Chitosan) was investigated for the sorption of Hg(II), CH3Hg(II) and C6H5Hg(II). The pHZpc values were found to be 7.5 and 7.9 for G-Chitosan and BG-Chitosan respectively. Batch experiments were conducted to study the effect of adsorption under different pH (1–10), temperature (30–70 °C) and contact time (20–180 min) conditions. The optimum pH was found to be 4.5 and 6–8 for Hg(II), CH3Hg(II) and C6H5Hg(II) respectively in case of G-Chitosan while in case of BG-Chitosan it was >8 for CH3Hg(II) and 7 for Hg(II) and C6H5Hg(II). Adsorption was found to be endothermic in the case of Hg(II) and exothermic for CH3Hg(II) and C6H5Hg(II). FT-IR analysis showed the possibility of metal binding to amino groups and free aldehyde groups of G-Chitosan and amide N and O of BG-Chitosan.