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Solid electrode

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Solid electrode


The present invention provides a solid diamond electrode, a reactor, in particular a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond, and methods in which the reactors are used.

Inventors: Jonathan James Wilman, Patrick Simon Bray, Timothy Peter Mollart
USPTO Applicaton #: #20120312682 - Class: 204280 (USPTO) - 12/13/12 - Class 204 
Chemistry: Electrical And Wave Energy > Apparatus >Electrolytic >Elements >Electrodes



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The Patent Description & Claims data below is from USPTO Patent Application 20120312682, Solid electrode.

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The present invention relates to a reactor comprising a solid diamond bipolar electrode for use in a method of treating waste water.

All documents referred to herein are hereby incorporated by reference.

Waste water contains a number of pollutants which may be organic or inorganic in nature e.g. cyanides and phenols. Electrochemical oxidation of waste water is a well known method for reducing the amount of pollutants present.

Electrochemical processes are preferred as compared to the use of powerful chemical oxidants on the basis that they are safer and more environmentally friendly.

It is known that the size of the electrochemical reaction surface in a reactor is key to the rate of electrochemical reaction that occurs. Therefore, the larger the available surface area, the greater the rate of electrochemical oxidation. With this in mind, bipolar electrode arrangements are of particular interest. A bipolar electrode is created by placing a third electrode between a cathode and an anode. Upon application of a potential between the anode and cathode, the bipolar electrode functions both as an anode and a cathode, vastly increasing the available anode and cathode surface area while still requiring only two electrical connections.

Diamond electrodes, in particular, boron-doped diamond electrodes are useful in electrochemical applications owing to a number of properties, which are significantly different to the properties of other electrode materials such as glassy carbon or platinum. These properties include the high hardness, high thermal conductivity and chemical inertness associated with diamond and the wide electrochemical potential window of conductive diamond.

The use of both solid diamond electrodes and diamond coated electrodes in electrochemical systems has been described. For example, EP 0 659 691 and U.S. Pat. No. 5,399,247 describe solid diamond electrodes and coated diamond electrodes used as the anode in a method of treating a solute in a liquid solution. In general, diamond coated electrodes are preferred because they are cheaper to make, with the absolute cost of a solid diamond electrode being significantly higher than that of a diamond coated electrode. There are a number of other advantages to diamond coated electrodes taught by the prior art, including enhanced toughness provided to the electrode by the substrate, for example where this is a metal.

The use of diamond coated bipolar electrodes in an electrochemical cell has been described in U.S. Pat. No. 6,306,270.

In the context of electrochemical processes, there is a continuing need for electrodes with increased operational lifetimes. Diamond coated electrodes suffer from the problem of pin-holes which allow the liquid being treated to penetrate the coating and electrochemically attack the interface between the diamond coating and substrate resulting in delamination. This is a problem that can be reduced by increasing the thickness of the diamond coating. However, to increase the thickness of the diamond coating is generally understood to be undesirable as it significantly increases production time and material costs. The problem of short operational lifetimes of electrodes is one which is exacerbated where the electrodes are driven at high current densities.

Solid diamond electrodes have longer lifetimes, however, a disadvantage of such electrodes is achieving the required conductivity as compared to a diamond coated electrode where the substrate which is coated with the diamond provides the conductivity and hence the conductivity of the diamond layer is less of a concern.

Generally, in order to achieve the required conductivity, heavy doping of diamond is required. It has, however, been found that heavily doped regions in diamond electrodes tend to be eroded more quickly through etching by organic solvents than lightly doped regions.

In order to overcome this problem, WO2006/013430 describes that erosion of a solid diamond electrode can be reduced by coating the working surface(s) of the electrode with a thin layer of lightly doped diamond (i.e. a passivation layer). This has the effect of reducing erosion at the working surface(s) while maintaining the required conductivity in the bulk of the diamond layer. However, it adds an additional coating step to the production process or an additional step during deposition wherein the boron concentration has to be adjusted.

WO 2006/061192 describes a method and a device for treating waste water containing pesticides. In the method described, the waste water to be treated is passed through an electrochemical cell comprising a boron doped diamond electrode.

US 2004/003176 describes the electrolytic disinfection of drinking water using an electrochemical cell comprising an anode positioned between two gas diffusion electrodes. The anode may be a boron doped diamond electrode.

An object of the present invention is to provide a reactor which maximises the available electrochemical reaction surface and to obtain a long operational lifetime without requiring additional production steps.

The present invention provides a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond and the diamond comprises a dopant such that the diamond is conductive and has an electrical resistivity of 1 MΩcm or less and wherein the average concentration of the dopant in a region of at least one of the major working surfaces, to a depth of 50 nm, is at least 8×1019 atoms/cm3.

In this way the electrochemical cell has solid diamond electrode(s) in a bipolar arrangement. This results in an increase in the operational lifetime of the at least one bipolar electrode while avoiding the need for additional production steps.

Advantageously, solid diamond can be used as a bipolar electrode without the need to alter the concentration of dopant present at the major working surfaces which will be in contact with the electrochemical environment to form a passivation layer. Surprisingly long operational lifetimes are observed, even at high current densities

The term “bipolar electrode” as used hereinafter refers to an electrode which, when placed between an anode and a cathode across which a potential is applied, will behave as both an anode and cathode. Thus a bipolar electrode necessarily has two major working surfaces in contact with the electrolyte. Furthermore, a bipolar electrode does not require a separate electrical connection, although one or more may be provided for monitoring purposes, for example.

The present invention also provides an electrode consisting essentially of diamond wherein the diamond comprises a dopant such that the diamond is conductive and has an electrical resistivity of 1 MΩcm or less and wherein the average concentration of dopant in a region of a least one of the major working surfaces, to a depth of 50 nm, is at least 8×1019 atoms/cm3 and wherein the electrode has at least one of the following features: a) the concentration of dopant atoms in any 1 mm3 volume does not vary from the concentration of dopant atoms in any other 1 mm3 by more than 50%, b) the uniformity of doping through the thickness of the electrode when measured by SIMS at at least five points approximately uniformly spaced through the thickness is such that the maximum dopant concentration is less than about 150% of the mean value and the minimum concentration is greater than about 50% of the mean value, c) a thickness in the range 0.2 mm to 5 mm, d) at least one lateral dimension of at least 10 mm, and, e) a surface area of at least 10 cm2.

Preferably the electrode of the present invention has at least two, preferably at least three, preferably at least four, preferably all five of features a) to e) above.

The electrode of the present invention may be used as the bipolar electrode in the reactor of this invention. All features of the electrode of the invention described herein may also be present in the bipolar electrode of the reactor of this invention. As used herein, the term electrode must be understood to refer to the characteristics of the bipolar electrode of the reactor of this invention.

The term “diamond” includes but is not limited to diamond which has been made by a chemical vapour deposition (CVD) process, preferably a microwave plasma CVD process, diamond made by a high temperature—high pressure process and natural type fib diamond. The diamond may be polycrystalline or single crystal diamond. Preferably the diamond is polycrystalline diamond, preferably made by CVD

The term “consisting essentially of” as used herein requires that the functional behaviour of the electrode is provided by diamond and the dopants within it, and in particular that there is no other identifiable material such as a substrate, providing useful function to the electrode. This term is not intended to preclude the possibility that other components or features may be added to the electrode, for example one or more electrical connections may be added using metallization, brazing or other bonding means.

An advantage of the invention is that the need for a passivation layer at the surface of the bipolar electrode is avoided. Passivation layers are known in which the working surface of the electrode is only lightly doped compared to the bulk. In contrast, it is a feature of the present invention that the average concentration of the dopant in a region of a major working surface to a depth of 50 nm is at least about 8×1019 atoms/cm3. In this way, the region of the diamond at the at least one major working surface is doped sufficiently highly for the diamond in this region to be conductive.

Preferably the average concentration of dopant in a region of both major working surfaces to a depth of 50 nm is at least 8×1019 atoms/cm3.

The average concentration of dopant in a region of a major working surface to a depth of about 50 nm may be determined using any technique used conventionally in the art.

Preferably the region of the major working surface in which the average concentration is determined is across substantially the entire major working surface(s).

An example of a suitable technique is secondary ion mass spectrometry (SIMS) depth profiling. SIMS is a very sensitive technique which can be used to perform elemental analysis of thin layers, typically in the range of a few nm to a few μm. In this technique, the surface is sputtered by a primary ion beam and the portion of sputtered material that leaves the surface as ions is analysed by mass spectrometry. By comparing the count rate of a particular species to a standard concentration and by determining the depth of the sputter hole, a profile of depth vs concentration can be generated. A set of values can be taken in a given area and then averaged.

The average concentration of the dopant can be determined over the whole surface. In practical terms, however, it is more usual to take a set of values in a given area and then average them.

The average concentration of the dopant may be measured in a square of area of about 0.01 mm2, 0.05 mm2, 0.10 mm2, 0.20 mm2, 0.25 mm2, 0.5 mm2, 1 mm2 on a working surface to a depth of about 50 nm from the major working surface.

The present invention is not limited by reference to the technique used to determine the average value. For example, one technique which may be employed is a “17-point array technique”. This technique involves taking a measurement by SIMS at 17 different points in the area defined on the surface of the bipolar electrode. The values are generally recorded from the raw “as-grown” conductive diamond wafer. The 17-point array technique is particularly appropriate for use where the diamond wafer has been produced by a microwave plasma technique as such a diamond wafer will typically have a circular shape.

With reference to all of the measurements used to characterise the material of the electrode of the present invention, the skilled person will understand that where the measurement is described as being made at a “point”, such as in the 17-point array technique, it is actually made over an area. The point to which reference is made is a point within the area and is generally the centre of the area over which the measurement is taken. As will be appreciated by the skilled person, the dimensions of the area over which the measurement is made are dependent on the technique in question. For example, resistivity measurements, using the four point probe technique described below, are generally made over an area of approximately 6 mm×1 mm (which are the dimensions of the probe). In contrast, SIMS measurements are made over an area which is typically less than about 0.5 mm×0.5 mm.

In the 17 point array technique, the 17 points are arranged with one point in the centre, eight points uniformly distributed around a perimeter located at a distance which is approximately 45% of the distance from the edge of the wafer to the centre, and eight points uniformly distributed around a perimeter located at a distance of approximately 90% of the distance from the centre to the edge. The measurements obtained are then averaged. While 17 points have been taken in the present case, it can be envisaged that an average over a fewer or a greater number of points can be obtained using the same technique.

As noted above, the average concentration of the dopant in a region of at least one of the major working surfaces, to a depth of 50 nm, is at least 8×1019 atoms/cm3.

Preferably the average concentration of the dopant in a region of at least one of the major working surfaces, to a depth of 60 nm, is at least 8×1019 atoms/cm3.

Preferably the average concentration of the dopant in a region of at least one of the major working surfaces, to a depth of 70 nm, is at least 8×1019 atoms/cm3.

Preferably the average concentration of the dopant in a region of at least one of the major working surfaces, to a depth of 80 nm, is at least 8×1019 atoms/cm3.

Preferably the average concentration of the dopant in a region of at least one of the major working surfaces, to a depth of 100 nm, is at least 8×1019 atoms/cm3.

In a further embodiment, the present invention provides a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond and the diamond comprises a dopant such that the diamond is conductive and has an electrical resistivity of 1 MΩcm or less and wherein the average concentration of the dopant in a region of least one of the major working surfaces, to a depth of 50 nm, is greater than ⅕ of the average concentration of the dopant in the remainder of the at least one bipolar electrode.

In this embodiment, preferably the average concentration of the dopant in a region of least one of the major working surfaces, to a depth of 50 nm, is greater than ¼ of the average concentration of the dopant in the remainder of the at least one bipolar electrode.

In this embodiment, preferably the average concentration of the dopant in a region of least one of the major working surfaces, to a depth of 50 nm, is greater than ⅓ of the average concentration of the dopant in the remainder of the at least one bipolar electrode.

In this embodiment, preferably the average concentration of the dopant in a region of least one of the major working surfaces to a depth of 50 nm is greater than ½ of the average concentration of the dopant in the remainder of the at least one bipolar electrode.

In this embodiment, preferably the average concentration of the dopant in a region of least one of the major working surfaces to a depth of 50 nm is not significantly less than the average concentration of the dopant in the remainder of the at least one bipolar electrode.

The average concentration of dopant at the surface of the electrode may for example be determined as described above. The average concentration in the bulk may, for example, be measured by preparing a cross-section, to reveal material originally forming the bulk, at a surface, and then by analysing this surface as described above.

A further physical property used commonly to describe an electrode is its resistivity. The electrical resistivity values as defined herein are the values as determined at room temperature or about 20° C. The resistivity of an electrode can be calculated by measuring the surface resistance and converting the value obtained to a bulk resistivity measurement.

For instance, a four point probe technique may be used to measure the surface resistance of an electrode. As is well known in the art, a four point probe consists of four, typically spring-loaded, electrodes arranged along a straight line. All four electrodes are placed in electrical contact with the surface under analysis. A current I is caused to flow between the two outermost electrodes. The current is normally fixed. The voltage between the two innermost electrodes is then measured. The measured voltage and the fixed current allow the determination of the surface resistance using Ohm\'s law, specifically:

R=V/I

where V is the voltage difference between the two measurement points and I is the forced current flowing between the two measurement points.

The resistance as determined above is determined at room temperature or about 20° C.

An example of a suitable apparatus for determining this measurement is a Jandel Cylindrical hand held Four point Probe in combination with a suitable meter such as a TTi BS407 Precision Milli/Micro Ohm meter.

The surface resistance measured can be used to calculate the electrical resistivity of the bipolar electrode using the relationship:

ρ=Rπt/ln 2

where t is the thickness of the bipolar electrode in cm and R is the resistance determined as defined above in Ω and the resistivity ρ is in Ωcm.

In general, the resistivity values are not corrected for either the spacing of the measurement points being similar to the thickness of the bipolar electrode nor for the fact that some of the measurements are being made close to the edge of the sample where the theory assumes a semi infinite plane.

As used herein and described above, the term “conductive”, means having an electrical resistivity at room temperature or about 20° C. of about 1 MΩ/cm or less, preferably about 1×105 Ωcm or less, preferably about 1×104 Ωcm or less, preferably about 1×103 Ωcm or less, preferably about 1×102 Ωcm or less, preferably 10 Ωcm or less, preferably 1 Ωcm or less.

Preferably, the electrode of the present invention has an electrical resistivity in the range from about 0.005 Ωcm to about 10 Ωcm, preferably from about 0.005 Ωcm to about 5 Ωcm, preferably from about 0.005 Ωcm to about 0.5 Ωcm, preferably from about 0.01 Ωcm to about 0.5 Ωcm, preferably in the range from about 0.02 Ωcm to about 0.4 Ωcm, preferably in the range from about 0.03 Ωcm to about 0.3 Ωcm, preferably about 0.04 to about 0.2 Ωcm, preferably in the range from about 0.05 Ωcm to about 0.152 Ωcm.

A method which may be used to determine an average value for a number of measurements across the surface is “17-point array technique” as described above. This technique is one of many which may be used to determine the average resistivity of the diamond electrode.

The diamond comprises one or more dopant elements in order that it is conductive. The dopant element may be selected from, for example, lithium, beryllium, nitrogen, phosphorous, sulphur, chlorine, arsenic, selenium or boron. Preferably the dopant element is boron. Boron has a low activation energy and thus provides a high conductivity at room temperature. Doping can be achieved by implantation but is preferably achieved by incorporation of the dopant element during synthesis of the diamond layer e.g. during synthesis of the diamond by microwave plasma CVD. An example of a suitable doping procedure where the diamond is polycrystalline diamond is as described in EP 0 822 269. An example of a suitable doping procedure where the diamond is single crystal diamond is, for example, described in WO 03/052174.

Where the dopant element is boron, it may be incorporated into the diamond during growth from solid, liquid or gaseous sources. The use of gaseous sources is preferred as these are easier to control. Gaseous sources of boron include boron hydrides such as BH3 and B2H6 and boron halides such as BF3 and BCl3. Preferably the boron source is B2H6 and the B2H6 is delivered in a carrier gas such as H2 at a concentration of between 1 ppm and 1000 ppm.

The average dopant concentration is preferably at least about 8×1019 atoms/cm3, preferably at least about 1.0×1020 atoms/cm3, preferably at least about 1.2×1020 atoms/cm3, preferably at least about 1.4×1020 atoms/cm3, preferably at least about 1.5×1020 atoms/cm3. The average dopant concentration is preferably less than about 3×1021 atoms/cm3, preferably less than about 2.0×1021 atoms/cm3, preferably less than about 4.0×1020 atoms/cm3, preferably less than about 6.0×1020 atoms/cm3.

Preferably, the dopant is dispersed uniformly throughout the electrode. The uptake of impurities or dopant element into a growing crystal such as CVD diamond can be sensitive to a number of factors. In particular, the uptake of dopant may be affected by the presence of other defects, such as dislocations or other impurities. In addition, the crystallographic face on which growth is taking place may also affect uptake of dopant. The common crystallographic faces in CVD diamond are the {100}, {110}, {111}, and {113} faces. The relative uptake of impurities in the growth sectors formed by these different faces is very different, and may also vary with growth conditions. For example, the {111} growth sector typically takes up somewhere between 10 and 30 times as much boron as the {100} growth sector. As a consequence of the differential uptake of boron between the different growth sectors, any CVD diamond which includes both the {111} and the {100} growth sectors, such as typical polycrystalline CVD diamond, shows huge local variations in boron concentration. It is for this reason that a minimum sample area or volume is generally specified for measurement of uniformity, these areas or volumes being sufficiently large to average out the concentration variations due to the polycrystalline nature of the diamond, but small enough to determine deleterious variation on a larger scale, for example from poor control of the synthesis conditions

In this context, the term “uniform” is intended to refer to the dispersion of dopant when viewed over the whole volume of the bipolar electrode and allows for the possibility that there may be local variations at some growth sectors. More specifically, it is preferred that the uniformity is such that the concentration of dopant atoms, as measured, for example by SIMS in any 1 mm3, preferably 0.2 mm3, preferably 0.03 mm3, volume does not vary from the concentration of dopant atoms in any other 1 mm3, preferably 0.2 mm3, preferably 0.03 mm3 by more than about 50%, preferably 30%, preferably 20%, preferably 10%.

Preferably, the uniformity of doping through the thickness of the electrode is such that for a series of at least 5 measurements taken at regularly spaced intervals along a line perpendicular to a major working surface of the electrode, the maximum dopant concentration measured is less than about 150%, more preferably less than about 130% of the mean value and the minimum dopant concentration is more than about 50%, preferably more than about 70% of the mean value. Preferably the end measurement point is positioned at a distance from the major working surface which is the same as the separation between adjacent measurement points.

An advantage of the present invention is that diamond may be used as the electrode in its as-grown form without requiring further processing. Preferably, one major working surface may be the as-grown nucleation face. Preferably, one major working surface may be the as-grown growth face. This is advantageous because it ensures that the flow of fluid across the surface of the electrode is turbulent thus minimising or preventing any formation of a stagnation layer.

The first major working surface may be the as grown nucleation face while the second major working surface may be the as grown growth face.

The as-grown growth face of the electrode preferably has a surface roughness, Ra of about 5 μm or more, preferably about 10 μm or more, preferably about 20 μm or more, preferably about 30 μm or more.

The average grain size at the growth surface is generally greater than the average grain size at the nucleation surface. The average grain size at the nucleation surface, where the average is the modal grain size, is preferably less than 5 μm, preferably less than 3 μm, preferably less than 1 μm.

The average grain size at the growth surface, where the average is the modal grain size, is preferably greater than t/40 μm, where t is the mean thickness of the layer in μm, preferably greater than t130 μm, preferably greater than t/20 μm.

Alternatively, the as-grown growth face and/or the as grown nucleation face may be processed to provide the bipolar electrode. For example, it may be advantageous to remove nucleation material from the nucleation face down to a given depth or it may be advantageous to process the growth face to provide a substantially flat surface modifying the growth sectors or crystallographic orientation of the exposed surfaces of individual grains presented at the surface. Additionally, it may be advantageous to trim the edges of the as-grown wafer prior to use as an electrode by a laser process or other process used conventionally in the art. One particular method of processing this type of conductive diamond is to use electro-discharge machining.

The electrode of the present invention may be of any size or shape as appropriate to the end application of the reactor. For example, the electrode may be square, rectangular, circular, cuboid or spherical. Preferably the electrode is planar. In applications where a pressure differential is maintained across the electrode, an electrode curved in three dimensions, for example in the form of a spherical segment, preferably with a large radius of curvature, may be beneficial. The electrode may have a longest dimension of at least about 10 mm, preferably at least about 30 mm, preferably at least about 45 mm, preferably at least about 60 mm, preferably at least about 95 mm, preferably at least about 120 mm. Preferably the longest dimension of the bipolar electrode is less than about 300 mm, preferably less than 200 mm, preferably less than 170 mm, preferably less than 150 mm.

Preferably the electrode has an absolute strength (fracture stress) as measured for the growth face, of greater than about 300 MPa, preferably greater than about 400 MPa, preferably greater than about 500 MPa, preferably greater than about 600 MPa, preferably in the range from about 350 MPa to about 650 MPa as measured using 3-point bending of 18×2 mm bars, depending on the thickness of the electrode tested. Typically an electrode with a thickness of approximately 550 μm would be expected to have a fracture stress of greater than about 500 MPa. The 3-point bending test is one with which the person skilled in the art will be familiar. In general terms, the sample to be tested rests across two parallel lines of contact. Along a line equidistant between the two lines of contact, a load is applied to the opposite face of the electrode to that being tested. The load required to cause the sample to fracture is recorded. The load required to cause fracture can then be converted into the fracture stress.

The term “major working surface” refers to the surface of the electrode which will be in direct contact with the electrolyte when in use, in the case of a bipolar electrode, will form the anode and cathode when in use. For example, in the case of a planar electrode which is rectangular, the major working surfaces will be the rectangular faces as illustrated in FIG. 1a. In the case of a circular shaped electrode, it is the two circular faces of the electrode which form the major working surfaces as illustrated in FIG. 1b. In the case of a spherical electrode, it can be envisaged that the surface of one hemisphere could form one major working face while the surface of the other hemisphere could form the other major working face. Preferably the major working surfaces of the electrode have a total surface area of greater than about 10 cm2, preferably greater than about 20 cm2, preferably greater than about 30 cm2, preferably greater than about 60 cm2, preferably greater than about 100 cm2, preferably greater than about 200 cm2, preferably greater than about 280 cm2, preferably greater than about 350 cm2.

Preferably the electrode is used with as-grown surfaces. The electrode is preferably substantially the same area as the as-grown wafer. This minimises wastage of diamond material. Preferably the as-grown wafer is circular. Preferably the electrode as used is circular. There are several advantages associated with a circular electrode. Firstly there is no stress concentration from sharp corners when the electrode is pressurised from one side. Stress concentration is a particular problem for the end electrode in a reactor or for any electrode adjacent to pressure fluctuations arising from the rapid flow of liquid through the reactor. Secondly, having a circular electrode means that the edge of the electrode is generally less difficult to seal than an electrode having a rectangular shape, because all parts of the seal are similar.

Preferably the electrode has a thickness in the range from about 0.2 mm to about 5 mm, preferably from about 0.2 mm to about 2 mm, preferably in the range from about 0.3 mm to about 1.5 mm, preferably in the range from about 0.4 mm to about 1.0 mm. Electrodes which have a thickness within this range are mechanically robust enough to be handled and can withstand the rigours of use while minimising cost and synthesis time, and the resistance in the bipolar cell.

Thickness uniformity may be measured using the 17-point array technique described above. The thickness uniformity of the bipolar electrode is preferably such that the minimum value is more than about 60%, preferably about 75%, more preferably about 80%, more preferably about 85% of the mean value and the maximum value is less than about 135%, preferably about 125%, more preferably less than about 120%, more preferably less than about 115%, of the mean value.

The reactor of the present invention comprises an anode, a cathode and at least one bipolar electrode positioned therebetween.

The reactor of the present invention may further comprise a container that is either substantially electrically insulating or sufficiently large and remote from the electrodes as to not carry a substantial fraction of the current which flows through the reactor. In use, the container holds a fluid that is electrically conductive, preferably a water-based fluid. In use, the electrodes are inserted into the electrically conductive fluid. An electrical power supply capable of passing current is connected to the anode and the cathode, such that an electrical current passes between the anode and cathode via the electrically conducting fluid and the at least one bipolar electrode.

Optionally the reactor may further comprise one or more of at least one fluid inlet and one fluid outlet; and at least one pump and associated pipework to permit the electrically conductive fluid to be circulated through the container, preferably via the inlet and outlet.

The reactor of the present invention may comprise at least about 2, preferably at least about 5, preferably at least about 8, preferably at least about 15, preferably at least about 20, preferably at least 30, preferably at least about 50, preferably at least 70, preferably at least about 100 bipolar electrodes positioned between the anode and the cathode.



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stats Patent Info
Application #
US 20120312682 A1
Publish Date
12/13/2012
Document #
13585000
File Date
08/14/2012
USPTO Class
204280
Other USPTO Classes
204294, 204292
International Class
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Drawings
7


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Chemistry: Electrical And Wave Energy   Apparatus   Electrolytic   Elements   Electrodes