Divergence electrodes

A gliding arc is an auto-oscillating periodic discharge between at least two diverging electrodes submerged in gas flow (Fig. 4-51). Self-initiated in the upstream narrowest gap, the... 

Figure 7.26 Schematic of a gliding arc with diverging electrodes [92].

In a limited number of experiments, in which six different hydrogen peroxide concentrations were examined with four different pH values, the validity of the procedure used was checked by comparing the results obtained with the sensor electrode to those obtained by means of titration. The results obtained with the sensor electrode have a maximum divergence of 3% compared with the concentrations obtained by titration. The final aspect of the amperometrical detection method that was examined at laboratory scale is the stability in time of a calibrated sensor electrode. 

In order to determine the accuracy of the solution proposed in Eq. (3.101) for the case of a microdisc electrode, in Fig. 3.13 numerical results are compared with this equation and also with the Oldham Eq. (3.95). Fully reversible, c[Jisc ss = 1000 /4, quasi-reversible, cj[lsc ss = nj4, and fully irreversible, cj[lsc ss = 0.001 /4, heterogeneous kinetics were considered under steady-state behavior. It is seen that, for fully reversible kinetics, both equations give almost identical results which are in good agreement with the simulated values. As the kinetics becomes less reversible, however, the results given by the two equations diverge from each other, with the simulated result lying between them. The maximum error in the Oldham equation is 0.5 %, and for Eq. (3.101), the maximum error is 3.6 %. 

The diffusion in the porous electrode can be described by Fick s law. We have for a redox reaction, the divergences for species O and R as... 

Although the data are not shown here, it will be mentioned that the CV and MSCV plots for benzene at Au(l 11)-0.6ML-Pd are not too different from those for Au(332)-0.82ML-Pd. In other words, reactions that occur at terrace sites are similar even if the structures of the underlying substrates are different [i.e., (Ill) vs. (332)]. Any noticeable divergence most likely arises from topographic differences as the smoother Au(lll)-Pd contains more contiguous uniform sites than the more corragated Au(332)-Pd electrode surface. 

Change in the position of the sorption front, which is in the part of the column positioned between electrodes, results in bridge imbalance that is registered by a potentiometer. Divergence of the needle, as a result, breaks the contact and a relay reacts. Resistance is increased if the sorption front has risen. If the front has lowered, resistance is reduced. Response of the electric motor of the proportional pump controlling solution flow in response to such signaling with respect to sorption front... 

---