Swiss-roll cell

The cell used (Fig. 16) is an undivided, so called Swiss-roll cell (Figs. 16 and 17) with a Ni mesh anode and a steel cathode. 

Fig. 17. Schematic diagram of the flow system used for batch and continuous oxidation of DAS (Diacetone-L-sorbose) with a swiss roll cell with an anode area of 3 m2...

Swiss Roll Cell This cell has been developed in Switzerland [89]. A commercial application is one oxidation step at a NiOOH anode in alkaline solution for the vitamin C production [22]. Mesh electrodes of stainless steel (cathode 1) and nickel (anode 3) are rolled up together with spacers of polypropylene mesh (2,4) on the central current feeder (5) and mounted in a cylinder (cells up to 1 m diameter, 200 m active area). The electrolyte streams axially through the cell. 

For laboratory scale conversions a simple beaker-type cell (Fig. 1) is convenient When lower current densities have to be applied or in big scale operations 21,26) the Swiss-roll cell is of advantage. The latter cell (Fig. 2) contains a rolled-up sandwich, consisting of an anode and cathode sheet and a separator net. This allows a high electrode area applied in a small cell volume, which results in the low current densities necessary for efficient electrolyses at the nickel hydroxide electrode. 

Fig. 2 Swiss-roll -cell, arrangement of the electrodes 1 Steel net cathode 2,4 Polypropylene net as insulating separator 3 Nickel net anode 5 Current feeder...

The Swiss-roll cell is commercially available from Dr. Robertson, P. M., Haldenstr. 9, 8185 Winkel, Switzerland... 

A special construction, called Swiss-Roll cell [13] (Fig. 22.12), is used for the application of the NiOOH electrode in the oxidation of primary alcohols to carboxylic acids. 

Figure 22.12 Swiss-Roll cell for the applications of NiOOH electrodes (1 = steel net cathode 2 + 4 = polypropylene net 3 = nickel net anode 5 = current feeder).

Mercury represents a serious environmental risk, and the study of removal of mercury from wastewater has received considerable attention in recent years. Mercury concentration was usually reduced by deposition on a cathode with high surface area. Removal of mercury is studied using extended surface electrolysis which reduces the level of mercury to below acceptable concentrations of 0.01 ppm in wastes by employing a Swiss roll cell with a cadmium-coated, stainless-steel cathode. An industrial cell with a fluidized bed electrode has also been studied. Graphite, as an efficient porous electrode, has been used to remove traces of mercuric ions form aqueous electrolyte solutions. In order to apply the electrochemical method for some effluents, it is necessary to use sodium hypochlorite to convert elemental mercury and less soluble mercury compounds to water-soluble mercuric-chloride complex ions. 

For cells that lack IR loss-increasing membranes, the Swiss-roll cell design (Ibl, 1975) may be the answer. Two metal foils act as electrodes and are separated by two insulating plastic masks that act as turbulence promoters. This cell gives large area and low IR. It is shown in Fig. 11.6. 

Fig. 11.6. Swiss-roll cell. (Reprinted from G. Kreysa, in Ulmann s Encyclopedia of Industrial Chemistry, Vol. 49, p. 200,1985, with permission from Wiley-VCH.)...

Swiss-roll cell — This cell was developed in Switzerland in 1982, and it is used on industrial-scale in case of the NiOOH electrode for the oxidation of primary alcohols to carboxylic acids, as, e.g., in vitamin C production. The electrolyte solution flows axially through the cell (see Figure), which is made up of rolled meshes of the nickel net anode and steel net cathode, separated from each other by polypropylene spacers, around the central current feeder rod. 

Cells with three-dimensional electrodes have bipolar electrodes such electrodes are characterized by the feature that one part of the electrode is anode and another part cathode. This can be realized in different ways, such as the pile capillary gap cell (Beck/Guthke cell. Chapter 32) [9,80], the Swiss roll cell [81], and packed- and fluidized-bell cells (Chapter 32) [82-84]. These cells are developed to meet economic demands, such as high space-time yield and simplicity in construction they are discussed in Chapter 31. 

A nickel anode is in alkaline solution protected against corrosion by a layer of nickel oxides. oxide (NiOOH) is capable of oxidizing a number of functional groups primary alcohols may be oxidized to carboxylic acids [158-161], which is of interest for the technical production of an intermediate for vitamin C production [162]. NiOOH chemically oxidizes the substrate and is regenerated electrochemically a large anode surface, which is realized in the Swiss-roll cell (Chap. 31), is thus advantageous. NiOOH electrodes in form of nickel foam electrodes has been found to be useful for the oxidation of diacetone L-sorbose to diacetone 2-keto-L-gulonic acid in the vitamin C synthesis [163]. 

Swiss-roll cell for NiOOH oxidations (Hoffman-La Roche). 

Figure 19. Swiss-roll cell arrangement of the electrodes.

The Swiss-Roll cell with a sandwich construction made from a pair of thin, flexible electrodes, wound with the interposition of a pair of separators for electrical insulation. The cell performance is achieved mainly by high electroactive area. The cathode product is removed by replacing the electrode module. 

Swiss-roll cell This cell, shown in Figure 26.14, has been proposed for both electro-organic syntheses and wastewater treatment [29, 37, 38]. It is fabricated from a multilayer stack of the following sheet materials (a) a polymeric cathode spacer cloth or mesh, (b) a cathode mesh, (c) an ion-exchange membrane, (d) a polymeric anode spacer cloth or mesh, and (e) an anode mesh. These sheets are assembled in the sequence a-b-a-c-de-d-... 

FIGURE 26.14 The Swiss-roll cell [30] (with kind permission from Springer Science and Business Media). 

Chemelec cell (inert fluidised bed) Swiss Roll cell... 

Figure 11.8 Design concepts of three further cells for metal recovery from dilute solutions of metal ions, (a) Cell with circulating bed cathode, (b) The Swiss-roll cell, (c) The trickle tower cell...

Figure 17.2 Schematic view of undivided eiectrochemical cells with a smaii inter-electrode gap. (a) Swiss-roll cell (b) capilla7 gap cell.

In efforts to improve the process efficiency of the electrodeposition alternative anode reactions have sometimes been employed. Cells such as the Enviro cell, the swiss roll cell, etc., have been used in applications which combine electrodeposition and anodic oxidation, typically that of cyanide, and some organics. Examples of other processes which couple together electrode reactions include ... 

The Swiss-Roll cell design introduced by Robertson, Scholder, Theis and lbl[15] for dilute solutions. This cell construction is characterized by an extremely high electrode surface to cell volume ratio amounting to 200 cm per cm. Additionally turbulence promoters are used in the cell to increase the current density,... 

Many such processes continue to use parallel plate reactors, a number of which are now available for purchase (e.g. the SU cell[37], the dished electrode cell[38] and the FM21 cell[22]) but many syntheses fail to be applied because economic assessments are based on unnecessarily complex designs and expensive cell components developed for other application e.g. membranes, Ti cell bodies, electrode materials. Hence it is particularly good to see the development and application of very cheap configurations, for example the new Monsanto process[24] or the Swiss Roll cell[35j. It is to be hoped that more companies give consideration to cell systems specifically designed for particular processes. 

Robertson and collaborators investigated the performance of a cloth turbulence promoter in a narrow gap (0.8 mm) associated with the Swiss Roll cell. Again mass transfer rates increased by a factor of 5 compared with those in the empty channel and were independent of electrode length. The mass transfer data were correlated by ... 

In an attempt to increase the specific electrode area of the reactor, electrodes, spacers, and separators are wound in a spiral form (Fig. 5.10) in the Swiss Roll cell. Electrolyte flows axially in the narrow channels between electrodes and separator. In this compact design, the main problem is the need for flexible foil electrodes, spacers, and separators and the cost and difficulty of replacing damaged components. Nevertheless, the design has been used for relatively small-scale organic applications. " ... 

Robertson, P. M., Cettou, P., Matic, D., Schwager, F., Storck, A., and Ibl, N., 1979, Electrosynthesis with the Swiss-Roll Cell. Properties of the cell components and their selection for electrosynthesis, Am. Instit. Chem. Eng. Symp. Ser. Electroorganic Synthesis Technology, 75 115-124. 

Fig. IM Examples of porous three-dimensional electrodes, (a) The Swiss-roll cell, showing its sandwich-and-roll structure. The electrodes may be single or multiple sheets or nets. The separator is selected from cloths, porous polymers or ion-exchange membranes. (b) The Enviro-Cell, which incorporates a profiled bed of carbon particles. In this manner, the current density is deliberately decreased towards the reactor outlet.

Ni anode in aqueous base. Undivided Swiss roll cell... 

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