Luminescence Study of the Interaction of Carboxymethyl Chitosan with Metal Ions

Abstract

The luminol/ carboxymethyl chitosan (CMCS) chemiluminescence (CL) system and the interaction of CMCS/metal ions (Mn+) were first studied by the flow injection (FI) CL method. It was found that CMCS with luminol could form a 1:1 complex, which accelerated the electron transfer from excited 3-aminophthalate, giving the enhanced CL intensity of luminol. The enhancement of CL intensity was proportional to the concentrations of CMCS with a linear range from 1.0·10–8 to 1.0·10–5 mol/l. It was also found that a number of Mn+ could influence the CL intensity of luminol/CMCS system. Based on the linear relationship between the decrement or enhancement of luminol–CMCS–Mn+ CL intensity and Mn+ concentration, the formation constant (Ka) and the stoichiometric ratio (n) of CMCS with Mn+ can be obtained with the help of two CL models. With increase in Mn+ valence, the Ka value increased from 104 to 108. The binding ability of Mn+ is similar to CMCS and follows the order Ce(IV) > Sn(IV) > Bi(III) > Fe(III) > Cr(III) > Al(III) > Pb(II) > Mn(II) > Zn(II) > Cu(II) > Ni(II) > Ag(I). This basic study can be helpful for the treatment of heavy metal ions in waste water.