Investigations of different chemiluminescent peaks in H2O2-SCN(-)-Cu(2+)-OH(-)-luminol flow system

In the H2O2-SCN(-) -Cu(2+)-OH(-)-luminol oscillatory system of chemiluminescence, the effects of the ingredient concentrations, temperature, flow rate and complexing agent on the oscillatory dynamics were investigated in a continuous-flow stirred tank reactor (CSTR). The dynamical structure of two peaks during a period was discussed in detail. By addition of EDTA to the oscillating system, the peak I height decreased sharply while the peak II height was little affected, and the period kept constant. This may be due to the fast reaction between Cu(II) and EDTA and the highly stable complex Cu(II)-EDTA. From the experimental study and mechanism analysis, the chemiluminescent peak I corresponds to Cu(II) → Cu(I) transformation and the peak II corresponds to the Cu(I) → Cu(II) transformation process. The key species involving in the two-transformation process are inferred to be superoxide radical and hydroxyl radical.