Experimental systems rotating disk

The experimental setup of a rotating hemispherical electrode (RHSE) is similar to that of a rotating disk electrode [50]. The basic system consists of a removable hemispherical electrode, and a variable speed rotator equipped with a provision, such as the slip-ring contact, to make electric connection to the hemispherical electrode during the experiments. 

The objective of the mass transport lab is to explore the effect of controlled hydrodynamics on the rate at which a mass transport controlled electrochemical reaction occurs on a steel electrode in aqueous sodium chloride solution. The experimental results will be compared to those predicted from the Levich equation. The system chosen for this experiment is the cathodic reduction of oxygen at a steel electrode in neutral 0.6 M NaCl solution. The diffusion-limited cathodic current density will be calculated at various rotating disk electrode rotation rates and compared to the cathodic polarization curve generated at the same rotation rate. 

The principle of the experimental arrangement devised for the transfer-fimction measurements involving a nonelectrical input quantity was given previously in Figures 14.2 and 14.3. In this section, a few examples are presented. The transfer function corresponding to the response of the electrochemical system to a perturbation of the rotation speed of a rotating disk electrode is given in Chapter 15. 

Another most remarkable experimental study in which the two types of mixed-mode sequences were also observed was carried out by Albahadily et al, who studied the electrodissolution of copper in phosphoric acid from a rotating disk. Figure 30 shows a series of Farey states observed in this system, and in Fig. 31, the experimentally observed mixed-mode states are listed in the structure of a Farey tree. On the high rotation-rate end of the 1° state, alternating periodic and chaotic behavior appeared. The first period-doubled oscillation arising from the P parent state is reproduced in Fig. 32 together with the P parent state. In Fig. 33, a two-parameter bifurcation diagram is depicted in which the succession... 

The experimental apparatus Includes 1) a rotating disk system (RDE) to mount a test wafer, control the rotating speed, and adjust the distance between the cathode and anode ... 

LeckerDN, Khan A (1998) Model for inactiveition of oc-amylase in the presence of salts theoretical and experimental studies. Biotechnol Prog 14(4) 621-625 Lee SL, Burt A, Russotti G et al. (1995) Microfiltration of recombinant yeast cells using a rotating disk dynamic filtration system. Biotechnol Bioeng 48(4) 386-400 Lee KW, Bae HA, Shin GS et al. (2006) Purification and catalytic properties of novel enantiose-lective Upase from Acinetobacter sp. ES-1 for hydrolysis of (S)-ketoprofen ethyl ester. Enzyme Microb Technol 38(3 ) 443 48... 

Figure 10.36 Experimental study of cavitation corrosion (a) rotating disk in the turbulent-flow regime (b) vibrating device and (c) Venturi system.

From the experimental point of view, for reductions, DC-polarography at the dropping mercury electrode (DME) or cyclic voltammetry (CV) at the hanging mercury drop electrode (HMDE) were used and for controlled-potential electrolyses at negative potentials, a mercury pool electrode was employed. For both oxidative and reductive experiments, voltammetry at the platinum rotating disk electrode (RDE) and CV at the stationary platinum electrode were applied. All experiments were performed in a three-electrode system with a platinum counter electrode. For measurements in analytical scale (a standard aminocarbene concentration was 3x 10-" mol/1), an undivided cell for 5-10 ml was used and for preparative electrolyses a two-compartment cell of the H-type was employed [14]. The potentials were referred to the saturated calomel electrode (SCE), which was separated from the investigated solution by a double-frit bridge. 

Eccentric rotating disks, (a) Cross section of the experimental geometry, (b) Top view showing particle paths, (c) Relative displacements of particles in a coordinate system rotating with the lower disk. 

The molecular degradation in turbulent flow is also explainable by the theoretical model of Brostow (62-64) (see Fig. 7). The mid chain scission in turbulent flow has been experimentally and theoretically explained (143-145,147). Recently, Kim and co-workers (153) studied the mechanical degradation of high molecular weight polystjmene under turbulent flow using a rotating disk apparatus for three various solvent systems. They found that the extent of the... 

Over the years, many systems have been investigated and a variety of experimental probes, both electrochemical and spectroscopic, have been used in their study and characterization. Thus, electrochemical techniques such as rotated-ring disk electrodes (JlL) and spectroscopic techniques such as Raman (18-201 (in its numerous variants) have provided much insight into the mechanisms of many of these processes, however, in-situ structural studies of such systems have, to date, proved very elusive to direct experimental probing. 

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