Micro-plate electrode cell and use thereof
The invention relates to an electrolysis cell for the particularly efficient treatment of wastewater polluted with organic substances by electrooxidative degradation of the wastewater constituents contributing to the chemical oxygen demand, and also its use.
1. An electrolysis cell comprising at least one inlet and at least one outlet for the electrolyte, further comprising a number of planar electrodes provided with openings through which flow can occur, of which at least one is, by means of functional coating, configured as anode having an increased overpotential for the formation of oxygen compared to the standard hydrogen electrode and at least one further electrode is configured as counterelectrode or cathode, which electrodes, on the basis of their polarity, are arranged in an alternating or pairwise alternating sequence to form a stack, further comprising a number of frame elements which in each case are arranged singly between neighbouring electrodes, where the frame elements simultaneously ensure mutual electric insulation, mutual fluid sealing and a defined spacing between the adjoining electrodes and the electrode stack formed in this way is installed between the inlet and the outlet in such a way that an electrolyte path through which flow can occur and which is sealed fluidically from the surroundings is formed from the inlet through the electrode stack to the outlet, wherein
neighbouring electrodes have a mutual clear spacing of not more than 0.5 mm,
the openings through which flow can occur in the electrodes are configured as parallel slits or rows of slits which break through the electrodes essentially perpendicularly to the surface thereof, where the individual slits have a width of not more than 1.5 mm and a length of at least three times the width and have a clear spacing perpendicular to their maximum dimension of at least twice the slit width, and
the slits or rows of slits in neighbouring electrodes in each case run parallel to one another and are arranged in a defined offset manner relative to one another perpendicularly to the maximum dimension of the slits or rows of slits in such a way that the spacing between one row of slits in an electrode to each immediately adjacent row of slits in the directly adjacent electrodes varies by not more than 25%.
2. The electrolysis cell according to claim 1 , wherein the anodes are coated with diamond or diamond-like carbon which has been made electrically conductive.
3. The electrolysis cell according to claim 1 , wherein the anodes comprise a base material, where the base material is a metal.
4. The electrolysis cell according to claim 3 , wherein the metal is selected from the group consisting of niobium, tungsten, tantalum, titanium, doped silicon and alloys of these metals.
5. The electrolysis cell according to claim 1 , wherein the cathodes are made of a material selected from the group consisting of stainless steels, nickel-based alloys, copper (alloys) and aluminium (alloys).
6. The electrolysis cell according to claim 1 , wherein the width of the slits is less than half the thickness of the electrodes.
7. The electrolysis cell according to claim 1 , wherein the width of the slits assumes values of from 0.2 mm to 0.8 mm.
8. The electrolysis cell according to claim 1 , wherein a spacing of the slits or rows of slits within each electrode and also in all electrodes within the cell varies by not more than ±10% and assumes values in the range from 2 mm to 10 mm.
9. The electrolysis cell according to claim 1 , wherein a mutual clear spacing between adjacent electrodes assumes values of from 0.2 mm to 0.4 mm.
10. The electrolysis cell according to claim 1 , wherein the electrodes have a thickness in the range from 0.2 mm to 1.5 mm.
11. The electrolysis cell according to claim 1 , wherein the frame elements arranged between the electrodes are either configured as flat-sealing elastomeric film whose thickness defines the mutual spacing of the electrodes and which at the same time brings about fluidic sealing between adjacent electrodes or consist of a nonelastomeric frame whose thickness defines the mutual spacing of the electrodes and also of one or two elastomeric sealing elements which provide the seal between the electrodes or between electrode and frame.
12. The electrolysis cell according to claim 1 , wherein the electrodes are provided on their exterior perimeter with contact tabs via which input or output of current can be effected without contact of the inlet leads and connecting elements with the electrolyte.
13. A process comprising:
producing the electrolysis cell according to claim 1 by making the electrodes of the electrolysis cell from predominantly lateral structuring a planar starting body having a thickness of not more than 2 mm.
14. A method of operating the electrolysis cell according to claim 1 , the method comprising:
installing the electrolysis cell in an apparatus that allows flow through the electrolysis cell in such a way that superficial velocities in the range from 0.3 m/s to 3 m/s are achieved within the slits in the electrodes of the electrolysis cell.