Analytical Sciences

Selective Adsorption of Mercury(II) on Chitosan Derivatives from Hydrochloric Acid

Yoshinari BABA * , Naohiko MATSUMURA, Kohichiro SHIOMORI and Yoshinobu KAWANO

Department of Materials Science, Faculty of Engineering, Miyazaki University, Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan

Crosslinked N-(2-pyridylmethyl)chitosan (PMC), N-(2-thienylmethyl)chitosan (TMC), and N-[3-(methylthio)propyl]-chitosan(MTPC) were newly synthesized as adsorbents of mercury(II). The amino group of the active adsorption site of chitosan was protected by Schiff's base formation prior to being crosslinked by 2-(chloromethyl)oxirane. The final chitosan derivatives were obtained by reducing the imine moiety of the Schiff's bases with sodium borohydride. The adsorption behavior of metal ions on the chitosan derivatives was examined from hydrochloric acid using a batchwise method. These chitosan derivatives exhibited high selectivities for mercury(II) over base metals in hydrochloric acid. Among the chitosan derivatives, MTPC especially exhibited high selectivity and a high loading capacity for mercury(II). The stoichiometric relations in the adsorption of mercury(II) on PMC and MTPC were clarified from hydrochloric acid. (Keywords: Chitosan, chitosan derivatives, adsorption equilibrium, adsorbed species, mercury(II), chelating formation)

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