Electrolytic Cell Comprising Multilayer Expanded Metal

Abstract

The present invention relates to an electrolysis cell comprising sheet-like anodes and cathodes which are separated from one another by means of separators and which are arranged in a cell trough or in a plurality of electrode frames clamped to one another and are connected in an electrically monopolar or bipolar manner, wherein the cathodes and/or anodes are in the form of multilayer expanded metal electrodes which consist of at least two expanded metal layers which are in contact with one another via internal resistance zones and through which the electrolyte solutions flow in the longitudinal direction, and to its use for the cathodic reduction or the anodic oxidation of organic or inorganic compounds.

1 . An electrolysis cell comprising sheet-like anodes and cathodes which are separated from one another by means of separators and which are arranged in a cell trough or in a plurality of electrode frames clamped to one another and are connected in an electrically monopolar or bipolar manner, wherein the cathodes and/or anodes are in the form of multilayer expanded metal electrodes which consist of at least two expanded metal layers which are in contact with one another via internal resistance zones and through which the electrolyte solutions flow in the longitudinal direction. 
   
   
       2 . The electrolysis cell as claimed in  claim 1 , wherein one or more intermediate layers of a porous electrode material are arranged between in each case at least two of the expanded metal layers through which flow takes place longitudinally and are in contact with said expanded metal layers. 
   
   
       3 . The electrolysis cell as claimed in  claim 1 , wherein the multilayer expanded metal electrode consisting of a plurality of expanded metal layers and optionally of porous intermediate layers has a specific electrode surface area which is from 5 to 100 times greater compared with a plate electrode. 
   
   
       4 . The electrolysis cell as claimed in  claim 1 , wherein the internal resistance zones are formed by the contact resistances between the expanded metal layers and/or between the expanded metal layers and the porous intermediate layers. 
   
   
       5 . The electrolysis cell as claimed in  claim 1 , wherein individual or a plurality of expanded metal layers and/or intermediate layers are separated from one another by spacers of electrically nonconductive material and are connected to one another in an electrically conductive manner only via laterally arranged contact surfaces, the current flowing through the multilayer expanded metal electrode in a meandering manner. 
   
   
       6 . The electrolysis cell as claimed in  claim 1 , wherein the multilayer expanded metal electrode packet is pressed, optionally with intermediate layers of porous material, by pressure means onto an electrode baseplate connected to the current supply, and contact is thus produced between the individual expanded metal layers and between said layers and the electrode baseplate. 
   
   
       7 . The electrolysis cell as claimed in  claim 1 , wherein a plurality of expanded metal segments separated by porous intermediate layers are provided with different current densities by separate supply lines and discharge lines for the electrolyte solutions, and wherein the electrolyte solution flows first through the segment closest to the opposite electrode and having the higher current density and then through the segment further away from the opposite electrode and having the lower current density. 
   
   
       8 . The electrolysis cell as claimed in  claim 7 , wherein the electrolyte flows in said separated expanded metal segments are hydrodynamically coupled to one another via the porous intermediate layer. 
   
   
       9 . The electrolysis cell as claimed in  claim 1 , wherein the expanded metal layers consist of stainless steel, nickel or copper or of valve metals coated by means of noble metals, noble metal oxides or doped diamond. 
   
   
       10 . The electrolysis cell as claimed in  claim 2 , wherein the individual expanded metal layers, the plastic spacers and optionally the intermediate layers of the porous electrode material have a thickness of from 1 to 5 mm and a void volume of at least 70%. 
   
   
       11 . The electrolysis cell as claimed in  claim 2 , wherein the porous intermediate layers consist of knitted metal wire fabrics, metal foams or nonwoven carbon fiber fabrics. 
   
   
       12 . The electrolysis cell as claimed in  claim 1 , wherein the multilayer expanded metal electrode is formed from an expanded metal web which is wound in the form of a spiral and is in contact with an outer or inner tube of a cylindrical hydrolysis cell, which tube is provided with the current supply. 
   
   
       13 . The electrolysis cell as claimed in  claim 1 , wherein, instead of individual or a plurality of expanded metal layers, expanded metal layers comprising woven metal wire fabrics are used. 
   
   
       14 - 18 . (canceled) 
   
   
       19 . A process for complete or partial cathodic reduction of organic and/or inorganic compounds which comprises using of the electrolysis cell as claimed in  claim 1 . 
   
   
       20 . The process as claimed in  claim 19 , wherein dyes in the form of dye solutions or solutions in dyeing works are cathodically reduced or wastewaters in dyeing works are decolorized. 
   
   
       21 . A process for the complete or partial anodic oxidation of organic and/or inorganic compounds which comprises using of the electrolysis cell as claimed in  claim 1 . 
   
   
       22 . A process for oxidative degradation of pollutants in process solutions and wastewaters which comprises using the electrolysis cell as claimed in  claim 1 . 
   
   
       23 . A process for removing metals from process solutions and wastewaters which comprises using the electrolysis cell as claimed in  claim 1 .