WO2013059964A1

WO2013059964A1 - An apparatus and method for electrocoagulation

Info

Publication number: WO2013059964A1
Application number: PCT/CN2011/001802
Authority: WO
Inventors: Zijun Xia; Hai Yang; Chihyu Caroline SUI; Yiwen Sun; Wei Cai
Original assignee: General Electric Company
Priority date: 2011-10-28
Filing date: 2011-10-28
Publication date: 2013-05-02
Also published as: TW201336787A

Abstract

The present disclosure describes a self-assembling, high surface area electrode. The self-assembling, high surface area electrode includes an electrode substrate, magnetic electrode particles and a magnetic field source. Under the influence of the magnetic field source, the magnetic electrode particles assemble on the surface of the electrode substrate. The self-assembling, high surface area electrode can be used as an anode and, or, a cathode in an electrocoagulation system for treating contaminated feed water. The self-assembling, high surface area electrode produces metal hydroxyl ions and metal hydroxide species to assist in the production of aggregates that remove contaminants in the feed water. The magnetic field source can be removed, which causes the magnetic electrodes to leave the surface of the electrode substrate for cleaning. Reintroduction of the magnetic field source causes re-assembly of the self- assembling, high surface area electrode.

Description

AN APPARATUS AND METHOD FOR ELECTROCOAGULATION

FIELD

[0001] The present disclosure relates generally to methods of water treatment and in particular to electrocoagulation.

BACKGROUND

[0002] The following discussion is not an admission that anything discussed below is citable as prior art or common general knowledge.

[0003] Electrocoagulation (EC) is an electrochemical method to remove contaminants from waste water. For example, the EC process has been used to treat food and protein waste water, nitrate and arsenic contaminated water, pulp and paper waste water, and textile waste waters (M. Kobya et al., "Treatment of Textile Waste waters by Electocoagulation Using Iron and Aluminum Electrodes" (2003) Journal of Hazardous Materials B100 at 163) and other industrial waste water. The EC process generally involves using an electric current and aluminum or iron or a combination of aluminum and iron electrodes to produce aluminum or iron hydroxyl ions and hydroxide species in situ. These metal ionic species are adsorbed onto the contaminants within the waste water to form coagulates. During the EC process, the coagulates can increase in cumulative mass and size and ultimately form aggregates. The aggregates are subsequently removed by sedimentation or filtration.

[0004] However, typical EC processes have inherent draw backs. One such inherent draw back is the degradation of the anode. The degradation of the anode occurs due to the electrolytic reactions that occur during a typical EC process. For example, the electric current causes electrolytic reactions to occur at the surface of both the cathode and the anode. At the surface of the cathode a reducing reaction occurs:

2H₂0 + 2e^" -> H₂ + 20ΗΓ (1 )

At the surface of the anode, for example an iron anode, the following oxidation reaction

Fe Fe^ + 2e (2) The Fe ions result in the production of various iron hydroxyl ions and hydroxide species, such as: FeOH²⁺; Fe(OH)₂ ⁺; Fe₂(OH)₂ ⁴⁺; Fe(OH)₄ ^"; Fe(H₂0)²⁺; Fe(H₂0)₅OH²⁺; Fe(H₂0)₄(OH)²⁺; Fe(H₂0)₈(OH)₂ ⁴⁺; and Fe₂(H₂0)₆(OH)₄ ²⁺. Collectively, these various hydroxyl ions and hydroxide species contribute to the formation of coagulates and aggregates. The production of the iron hydroxyl ions and hydroxide species depletes the iron anode

[0005] Therefore, a typical EC process cannot work as a continuous process because the production of metal hydroxyl ions and hydroxide species is a sacrificial process that degrades the metal anodes. This degradation requires that the EC process is regularly stopped to allow replacement of the sacrificed anode.

[0006] Additionally, either or both of the electrodes can foul during the EC process. Therefore, a typical EC process is also regularly stopped to wash or de-foul the electrodes.

[0007] Further, a typical EC process requires a large device with a sufficiently large electrode surface area to achieve the level of current density necessary to perform large scale industrial water treatment. For example, large volume treatment tanks with multiple stacks of electrodes are required to provide sufficient electrode surface area to treat water on an industrial scale. The issues of electrode replacement and cleaning are more complicated when there are multiple stacks of electrodes in a single tank. The EC process must be stopped each time an electrode requires replacement or cleaning in a given treatment tank.

SUMMARY OF THE INVENTION

[0008] The present disclosure describes a self-assembling, high surface area electrode and an electrocoagulation (EC) system. A method of cleaning the electrode and rebuilding the electrode are also described. The EC system may be used, for example, to remove contaminants from waste water.

[0009] The self-assembling, high surface area electrode includes an electrode substrate, magnetic electrode particles and a magnetic field source. Under the influence of the magnetic field source, the magnetic electrode particles assemble on the surface of the electrode substrate. In this manner, the electrode substrate, the magnetic field source and the magnetic electrode particles form a self-assembling electrode.

[0010] In the EC system, described in greater detail below, either or both of the electrodes are a self-assembling electrode. The EC system includes an EC cell vessel, a magnetic field source, an electrode substrate and a magnetic electrode particle. The electrode substrate and the magnetic electrode particles are contained in the EC cell vessel. Feed water that is to be treated by the EC system is introduced into the EC cell vessel. The magnetic electrode particles can, before assembly, be a fluid suspension of particles within the feed water.

[0011] In the presence of the magnetic field source the electrode substrate is enveloped within the magnetic field. When the electrode substrate is enveloped in the magnetic field, the magnetic electrode particles align within the field lines of the magnetic field and are attracted to the surface of the electrode substrate. The magnetic electrode particles move to directly, or through other magnetic electrode particles, contact the surface of the electrode substrate. In this manner, the magnetic electrode particles are a self-assembling electrode.

[0012] When the magnetic field source is removed, the magnetic electrode particles disassemble from the surface of the electrode substrate and return to a fluid suspension within the feed water. While the magnetic electrode particles are in the fluid suspension, they are physically cleaned and de-fouled by movement of the feed water within the EC cell vessel. In this manner, the electrode is a self-cleaning electrode. When the magnetic electrode particles are de-fouled, the magnetic field source can be reintroduced and the self-assembling electrode is rebuilt.

[0013] Magnetic electrode particles can be added in the EC process to replace the magnetic electrode particles that are sacrificed during the EC process. The electrode is rebuilt without requiring a stoppage of the EC process.

[0014] As will be described further below, various different magnetic electrode particles can be used, for example iron or a combination of iron and other materials. The electrode particles create an electrode surface area that is larger than a typical electrode plate. This larger electrode surface area allows for a greater electric current density to be applied to an EC system of given size.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional schematic drawing of a first self-assembling electrode.

[0016] Figure 2 is a cross-sectional schematic drawing of a second self-assembling electrode.

[0017] Figure 3 is a cross-sectional schematic drawing of a third self-assembling electrode.

[0018] Figure 4 is a schematic drawing of an electrocoagulation system.

[0019] Figure 5A is a cross-sectional schematic of an electrocoagulation system with multiple electrodes.

[0020] Figure 5B is a cross-sectional schematic of an electrocoagulation system with multiple electrodes.

[0021] Figure 5C is a cross-sectional schematic of an electrocoagulation system with multiple electrodes.

[0022] Figure 6 is an exploded schematic view of a contaminant removal apparatus.

[0023] Figure 7 is a cross-sectional schematic drawing of the contaminant removal apparatus of Figure 6.

DETAILED DESCRIPTION

[0024] Self-Assembling Electrode

[0025] Figure 1 shows a first self-assembling electrode 150. The first self-assembling electrode 150 comprises an electrode substrate 1 18, magnetic electrode particles 120 and a magnetic field source 122. The electrode substrate 1 18 is made of a conductive metal that does not act as a magnetic shield. Optionally, the electrode substrate 1 18 is not soluble in an electric field. For example, the electrode substrate 1 18 can be a plate made of titanium. The electrode substrate 1 18 acts as a physical support for the first self-assembling electrode 150.

[0026] The first self-assembling electrode 150 also comprises magnetic electrode particles 120. The magnetic electrode particles 120 may be in the form of a fluid suspension. A number of different materials are suitable for use as magnetic electrode particles 120. Suitable materials for use as magnetic electrode particles 120 are magnetic and will produce one or more metal hydroxyl ions and metal hydroxide species under oxidizing conditions. The various metal hydroxyl ions and metal hydroxide species help form aggregates of coagulates. The term magnetic refers to the inherent properties of the material to react to the influence of a magnetic field, for example, by aligning with the field lines of the magnetic field the magnetic electrode particles 120 move to contact the electrode substrate, directly or through other magnetic electrode particles 120 allowing the current to flow from the electrode substrate 1 18 through the magnetic electrode particles 120. A suitable material for the magnetic electrode particles 120 is iron particles of a size substantially in the range of 10 m to ΟΟΟμηι. These iron particles are magnetic and when exposed to an oxidizing condition one or more of the following iron hydroxyl ions and iron hydroxide species are produced: FeOH₂ ⁺; Fe(OH)₂ ⁺; Fe₂(OH)₂ ⁴⁺; Fe(OH)₄ ^"; Fe(H₂0)₂ ⁺; Fe(H₂0)₅OH₂ ⁺; Fe(H₂0)₄(OH)₂ ⁺; Fe(H₂0)₈(OH)₂ ⁴⁺; and Fe₂(H₂0)₆(OH)₄ ²⁺.

[0027] The first self-assembling electrode 150 also comprises a magnetic field source 122. The magnetic field source 122 of the first self-assembling electrode 150 is a permanent magnet 123. The permanent magnet 123 is housed in a separate chamber 126 that is physically separated from the first self-assembling electrode 150. The side of the electrode substrate 1 18 that is opposite to the separate chamber 126 is referred to as the assembly surface 124 of the electrode substrate 1 18. The assembly surface 124 is exposed to the magnetic electrode particles 120. The magnetic field source 122 produces a magnetic field of sufficient intensity to attract a material amount of magnetic electrode particles 120 to the assembly surface 124 of the electrode substrate 1 18. For the purposes of this disclosure, the phrase "a material amount" means enough magnetic electrode particles to increase the surface area of an electrode substrate by at least five times, or by a ratio substantially in the range of 25 to 1000: 1 , relative to the surface area of the electrode substrate in the absence of the magnetic field. The magnetic field strength may be substantially in the range of 100 to 10,000G per self-assembling electrode 150. Preferably, at least half of the total amount of magnetic electrode particles 120 in communication with the first self-assembling electrode 150 will assemble on the first self-assembling electrode 150. If there is more than one electrode substrate 1 18, then preferably at least half of the total amount of magnetic electrode particles 120 in communication with the electrode substrates 1 18 divided by the number of electrode substrates 1 18, will assemble on each electrode substrate 1 18. Although other particles within the influence of the magnetic field source 122 can be magnetic and therefore may align with the field lines of the magnetic field and move to contact the electrode substrate 1 18, these other particles do not oxidize to produce the various metal hydroxyl ions and metal hydroxide species that are required for the EC process. Therefore, these other particles do not contribute to the material amount of magnetic electrode particles 20 that are attracted to the assembly surface 124 of the electrode substrate 1 18.

[0028] When a material amount of the magnetic electrode particles 120 are attracted to the active surface 124 of the electrode substrate 1 18, the first self-assembling electrode 150 has a very high surface area. In a typical EC system, planar electrode plates are used. The typical planar electrode plates have a surface area that is defined by the length and width of the plate. For example, the first self-assembling electrode 150 of Figure 1 is formed on an electrode substrate 1 18 that has a length of 10cm and a width of 4cm, which results in an assembly surface 124 of the electrode substrate 1 18 having a surface area of 40cm². In comparison, when 20g of 40pm iron particles are used as the magnetic electrode particles 120, the first self-assembling electrode 150 has a calculated surface area of over 3800cm².

[0029] Figure 2 shows a second self-assembling electrode 250. This second self- assembling electrode 250 comprises an electrode substrate 1 8, magnetic electrode particles 120 and a magnetic field source 222. The electrode substrate 1 18 and the magnetic electrode particles 120 are as described above. The difference between the first self-assembling electrode 150 and second self-assembling electrode 250 is that the magnetic field source 222 of the second self-assembling electrode 250 is an electromagnet 228.

[0030] The electromagnet 228 includes a conduction wire 230 that conducts electric current. The conduction wire 230 can be connected to an electric power supply 206. When electric current flows through the conduction wire 230, an electromagnetic circuit is complete and an electro-magnetic field is created. The amount of electric current that flows through the conduction wire 230 determines the strength of the electro-magnetic field. An increase in the flow of the electric current will cause an increase in the strength of the electromagnetic field.

[0031] Optionally, the conduction wire 230 can be manipulated to further increase the strength of the electro-magnetic field. For example, the conduction wire 230 can be wound into a coiled structure 232. Additionally, the coiled structure of the conduction wire 230 can be wound around a ferromagnetic material to increase the strength of the electromagnetic field. Examples of suitable ferromagnetic materials include but are not limited to: iron, nickel, cobalt and various other known ferromagnetic alloys.

[0032] The use of an electromagnet 228 as a magnetic field source 222 provides the advantage of turning the electromagnetic field on and off by starting or stopping the flow of electric current through the conduction wire 230. Additionally, the strength of the electromagnetic field can be modulated by increasing or decreasing the amount of electric current flowing through the conduction wire 230 or manipulation of the conducting wire 230.

[0033] In the second self-assembling electrode 250, the electromagnet 228 can be housed in a separate chamber 126 that is physically separated from the second self- assembling electrode 250. The side of the electrode substrate 1 18 that is opposite to the separate chamber 126 is referred to as the assembly surface 124 of the electrode substrate 1 18. The assembly surface 124 is exposed to magnetic electrode particles 120. The magnetic field source 222 produces a magnetic field of sufficient intensity to attract a material amount of magnetic electrode particles 120 to the assembly surface 124 of the electrode substrate 1 18. [0034] The magnetic field produced by the electromagnetic circuit is in addition to any inherent magnetic field that may be produced by the flow of electric current through the electrolytic circuit. This inherent magnetic field is not a magnetic field of sufficient intensity to attract a material amount of magnetic electrode particles 120 to the assembly surface 124 of the electrode substrate 1 18. Whereas, the electromagnetic field produced by the electromagnetic circuit is of sufficient intensity to attract a material amount of the magnetic electrode particles 120 to the assembly surface 124 of the electrode substrate 1 18.

[0035] Figure 3 shows a third self-assembling electrode 350. The third self-assembling electrode 350 comprises an electrode substrate 318, magnetic electrode particles 120 and a magnetic field source 322. The magnetic electrode particles 120 are as described above for the first and second examples. The difference between the second self-assembling electrode 250 and the third of a self-assembling electrode 350 is that the magnetic field source 322 is an electromagnet 328 that is integrated within the electrode substrate 318. The electromagnet 328 can be integrated within the electrode substrate 318 by being housed within the electrode substrate 318 or by being wrapped around the outer surface of the electrode substrate 318. As will be described below, the integration of the electrode magnet 318 into the electrode substrate 318 allows the substrate to act as the magnetic field source 322 without the requirement of an external magnetic field source 322.

[0036] The electromagnet 328 is similar to the electromagnet 228 described above. The electromagnet 328 includes a conduction wire 230 that is connected to an electric power supply 206. The conduction wire 230 can similarly be manipulated to increase the electromagnetic field that is created when an electric current flows through the conduction wire 230. For example, the conduction wire 230 can be manipulated by wrapping the conducting wire 230 into a coiled structure 232 or wrapping the conduction wire around a ferromagnetic material. Optionally, the electrode substrate 318 is made of a ferromagnetic material and the coiled structure 232 is wrapped around the electrode substrate 318. When an electric current flows through the conduction wire 230 the electromagnetic circuit is complete and the electrode substrate 318 becomes the magnetic field source 322. The magnetic field source 322 can be turned on and off by controlling the electric current flow through the conduction wire 230. When the magnetic field source 322 is turned on, the magnetic electrode particles 120 can assemble on the active surface of the electrode substrate 318.

[0037] An additional difference between the second self-assembling electrode 250 and the third self-assembling electrode 350 is that the third self-assembling electrode 350 does not include a separate chamber 126 to house the magnetic field source 322. Therefore, the third self-assembling electrode 350 has a greater surface area act as the assembly surface 324 because there no physical separation between the surface of the electrode substrate 3 8 and the magnetic field source 322. In the first and second self- assembling electrodes 150, 250 there was only one assembly surface area 124, because the magnetic field sources 122 and 222 are physically separated from the electrode substrate 1 18. Whereas, in the third self-assembling electrode 350 the electrode substrate 318 is the magnetic field source 322 and multiple surfaces or the entire electrode substrate 318 surface can act as the assembly surface 324.

[0038] Any of the first, second and third self-assembling electrodes 150, 250, 350 can be used as an electrode in an electrocoagulation system 400, as described below.

[0039] Electrocoagulation System

[0040] Figure 4 shows an electrocoagulation (EC) system 400. The EC system 400 includes a feed water source 402, a pump system 404, an electric power supply 406, a treated water collector 408 and an EC cell 410. The feed water source 402 can be an industrial waste water stream that is contaminated with heavy metal ions, oil droplets or colloidal organic materials, colloidal inorganic materials or other contaminants. The pump system 404 pumps feed water from the feed water source 402 to the EC cell 410. Additionally, the pump system 404 can conduct treated water from the EC cell 410 to a treated water collector 408. The treated water collector 408 can be a system of pipes to transport the treated water, or the treated water collector 408 can be a holding vessel.

[0041] The electric power supply 406 can be a DC electric power source that provides electric power to the entire EC system 400 and to the various individual electric circuits within the EC system 400. As will be described below, the EC system 400 can have an electrolytic circuit that is separate from an electromagnetic circuit. Both of these circuits can be powered by the electric power supply 406. The electric current that flows through the electrolytic circuit can range from 10mA to 1500mA. The electric current that flows through the electromagnetic circuit is discussed further below.

[0042] The EC cell 410 is a vessel with an interior surface and an exterior surface. The EC cell 410 can be made of non-conducting materials or one of the surfaces of the EC cell 410 can have a non-conductive coating. The EC cell 410 has two electrodes, an anode 412 and a cathode 414. Collectively, the anode 412 and the cathode 414 are referred to as an electrode stack 440. The anode 412 is positioned towards one end of the EC cell 410. The cathode 414 is positioned towards the opposite end of the EC cell 410 as the anode 412. The EC cell 410 also contains feed water 416, generally between the anode 412 and the cathode 414. The electric power supply 406 is connected to both the anode 412 and the cathode 414 and the electrolytic circuit is completed between the electrodes by the various electrolytes present in the feed water 416.

[0043] An experimental set-up was designed to test the use of the first self-assembling electrode 150 in the EC system 400 as described above. In this set-up, the first self- assembling electrode 150 replaces the anode 412 of the EC system 400. The first self- assembling electrode 150 comprises an electrode substrate 1 8, magnetic electrode particles 120 and a magnetic field source 122 that is a permanent magnet 123. In this experiment, the permanent magnet 123 is housed in the separate chamber 126 that is positioned to one side of the EC cell 410, adjacent the exterior surface of the EC cell 410. The separate chamber 126 is positioned to one side of the electrode substrate 1 18 to form an assembly surface 124.

[0044] In this experiment, the electrode substrate 1 18 is a 4 x 10cm titanium plate and the cathode 414 is a similar 4 x 10cm titanium plate. The magnetic electrode particles 120 are iron particles with a particle size of approximately 40pm. The magnetic electrode particles 120 are suspended in one of two different samples of feed water 416. One feed water sample is retentate from a nanofiltration system. The second feed water sample is steam assisted gravity drainage (SAGD) produced water from a heavy oil extraction operation. The experimental set up measured the removal of silica and calcium ions from these two different feed water samples. The results below in Tables 1 and 2 are from a single pass through the EC cell 400 at rate of 50ml/min and at room temperature. The example results of the nanofiltration retentate sample are shown below in Table 1 and the example results of the SAGD produced water are shown below in Table 2.

[0045] Table 1 . Nanofiltration Retentate

[0046] Table 2. SAGD produced water.

[0047] As shown in both Table 1 and 2, silica and calcium were removed and there is a relationship between an increased electric current and the increased removal of silica and calcium ion from the two samples of feed water 416.

[0048] During the operation of the EC system 400 that uses the first self-assembling electrode 150 to replace the anode 412, the iron magnetic electrode particles 120 are sacrificed to produce the iron hydroxyl ions and the iron hydroxide species, which contribute to the formation of coagulates. Rather than stopping the EC process to replace the depleted iron particles, additional iron particles can be added into the EC system 400 by one or more additional doses of the magnetic electrode particles 120. The additional dose can be added at the feed water source 402 or directly into the feed water 416 within the EC cell 410. When the additional magnetic electrode particles 120 come within the influence of the magnetic field source 122, the additional magnetic electrode particles 120 align themselves within the field lines of the magnetic field and reinforce the depleted first self-assembling electrode 150. In this manner, the first self- assembling electrode 150 can be reinforced without the necessity of stopping the continuous EC process.

[0049] As the EC process continuously operates, fouling will occur at the first self- assembling electrode 150. To perform a washing and de-fouling of the first self- assembling electrode 150, the operator can temporarily remove the magnetic field source 122 from the separate chamber 126 so that the magnetic field no longer exerts an influence on the fouled magnetic electrode particles 120. The removal of the magnetic field source 122 causes the first self-assembling electrode 150 to disassemble by way of the magnetic electrode particles 120 leaving the assembly surface 124. When the magnetic electrode particles 120 leave the assembly surface 124 they return to a fluid suspension within the feed water 416. While the magnetic electrode particles 120 are within the feed water 416 they are subject to physical turbulence that can arise by the pump system 404. The turbulence of the feed water 416 washes and de-fouls the magnetic electrode particles 120. When the magnetic electrode particles 120 are de-fouled, the operator can re-introduce the magnetic field source 122 to the separate chamber 126 of the EC cell 410. This will rebuild the first self-assembling electrode 150 and the EC process can continue without a prolonged period of stoppage. [0050] The second self-assembling electrode 250 can also be used in the EC system 400 to replace the anode 412. The second self-assembling electrode 250 comprises a magnetic field source 222 that is an electromagnet 228 that is housed in the separate chamber 126.

[0051] As the EC process continues to operate with the second self-assembling electrode 250, one or more additional doses of magnetic electrode particles 120 can be added to the feed water 416 to reinforce the second self-assembling electrode 250, as described above.

[0052] As the EC process continues to operate and fouling of the second self- assembling electrode 250 occurs, the flow of electric current through the conducting wire 230 can be stopped. When the flow of electric current through the conducting wire 230 stops, the magnetic field source 222 dissipates and the second self-assembling electrode 250 disassembles by way of the magnetic electrode particles 120 leaving the leaving the assembly surface 124. As described above, the magnetic electrode particles 120 enter the feed water 416 where they are subjected to the physical turbulence within the feed water 416. The turbulence of the feed water 416 washes and de-fouls the magnetic electrode particles 120. When the magnetic electrode particles 120 are de-fouled, the operator can direct electric current flow through the conducting wire 230 to re-establish the magnetic field source 222. The re-establishment of the magnetic field source 222 will cause the magnetic electrode particles 120 to reassemble on the assembly surface 124 of the electrode substrate 1 18, which rebuilds the second self-assembling electrode 250.

[0053] The third example of the self-assembling electrode 350 can also be used in the EC system 400 to replace the anode 412. The third example of a self-assembling electrode 350 comprises a magnetic field source 322 that is an electromagnet 328 that is integrated in the electrode substrate 318. If the third self-assembling electrode 350 is used to replace the anode 412 of the EC system 400, then one or more additional doses of magnetic electrode particles 120 can be used to reinforce the depleted magnetic electrode particles 20 that are assembled upon the assembly surface 324 of the electrode substrate 318. Additionally, as described above, the third self-assembling electrode 350 can be de-fouled by removing the magnetic field source 322. The operator can dissipate the magnetic field source 322 by stopping the flow of electric current through the conducting wire 230. Similarly, when the magnetic electrode particles 120 are de-fouled by the turbulence of the feed water 416, then the magnetic field source 322 can be re-established by initiating the flow of electric current through the conducting wire 230. Re-establishment of the magnetic field source 322 causes the self-assembling electrode 350 to rebuild.

[0054] The first, second or third of the self-assembling electrodes 150, 250, 350 can be used to replace the anode 4 2 in the EC system 400. This replacement of the anode 412 causes a disparity between the surface area of the self-assembling electrode 150, 250, 350 and the surface area of the cathode 414, if the cathode 414 is a typical plate cathode. A disparity in electrode surface areas will limit the current density that can be used. For example, if the first self-assembling electrode 150 has a greater surface area than the cathode 414 it is the smaller surface area of the cathode 414 that will limit the current density between the two electrodes.

[0055] A solution to this surface area disparity is to use the first, second or third self- assembling electrode 150, 250, 350 to replace both the anode 412 and the cathode 414. The replacement of both the anode 412 and the cathode 414 with a self-assembling electrode 150, 250, 350 will provide high surface areas at both electrodes of the electrolytic circuit and allow the use of higher current densities.

[0056] Use of the first, second or third self-assembling electrode 150, 250, 350 to replace the anode 412 and the cathode 414 will establish two magnetic field sources 122, 222, 322 at either end of the EC cell 410. The two magnetic field sources may compete for the magnetic electrode particles 120 between the two self-assembling electrodes 150, 250, 350. This competition for the magnetic electrode particles 120 can also cause a disparity between the surface areas of the two self-assembling electrodes 150, 250, 350. The surface area disparity between the electrodes caused by competing magnetic field sources can be smaller than the disparity caused by the use of one self- assembling electrode 50, 250, 350 and a typical plate cathode 412. One solution to the surface area disparity caused by competing magnetic field sources can include a homogenous suspension of the magnetic electrode particles 120 within the feed water 416 and a simultaneous introduction of both magnetic field sources. For example, if the first self-assembling electrode 150 is used as the anode 412 and the cathode 414, then each permanent magnet 123 is placed into its respective, separate chamber 126 at the same time.

[0057] When the first self-assembling electrode 150 is used as both the anode 412 and the cathode 414, the de-fouling procedure can include removing both permanent magnets 123 from the respective, separate chambers 126 for an overlapping period of time. Following the de-fouling procedure, the permanent magnets 123 can be reintroduced into their respective separate chambers 126 simultaneously, as described above.

[0058] When the second self-assembling electrodes 250 is used as the anode 412 and the cathode 414 the start of electric current flow through the conducting wires 230 of each electromagnet 228 can be simultaneous to reduce any electrode surface area disparity between the two self-assembling electrodes 250.

[0059] When the second self-assembling electrode 250 is used to replace the anode 412 and the cathode 414, the de-fouling procedure can include stopping the flow of electric current through the conduction wires 230 of the two electromagnets 228. Following the de-fouling procedure, the flow of electric current through the conducting wire 230 of the electromagnets 228 can be simultaneously initiated to reduce any surface area disparity between the two self-assembling electrodes 250.

[0060] When the third self-assembling electrode 250 is used to replace the anode 412 and the cathode 414, the solution to any electrode surface area disparity and the de- fouling procedure can be used as described above for the second self-assembling electrode 250.

[0061] Figure 5A depicts another EC system 500. This EC system 500 includes the same features of the EC system 400, such as a feed water source, a pump system and a treated water collector, all of which are not shown in Figure 5. The EC system 500 includes an EC cell 510 that has two outer electrodes, multiple inner electrodes and an electric power supply 506. [0062] EC system 500 can be a bipolar arrangement where only the two outer electrodes are connected directly to the electric power supply, forming the anode 512 and cathode 514. The multiple inner electrodes are inner electrode substrates 519, that are positioned between the anode 512 and the cathode 514. The inner electrode substrates 519 can be the same as the previously described electrode substrates 1 18, 318. In the bipolar arrangement, the inner electrode substrates 519 are indirectly affected by the electrical potential between the anode 512 and the cathode 514. The sides of each inner electrode substrate 519 has the opposite charge compared with the parallel side of the next inner electrode substrate 519 or the anode 512 or cathode 514, as the case may be.

[0063] In the EC system 500 shown in Figure 5B, the anode 512 can be replaced by a self-assembling electrode 550 and the cathode 514 can be a plate electrode. The self- assembling electrode 550 includes an electrode substrate 518, magnetic electrode particles 520 and a magnetic field source 522. The self-assembling electrode 550 is similar to any of the first, second or third self-assembling electrodes 150, 250, 350, as described above. The magnetic field source 520 is of sufficient intensity to cause a material amount of the magnetic electrode particles 520 to be attracted to and assemble upon the electrode substrate 518 and the multiple inner electrode substrates 519.

[0064] When only the anode 512 is replaced by self-assembling electrode 550 there is only one magnetic field source 522 within EC cell 510. The one magnetic field source 522 can be located at one end of the EC cell 510. Optionally, if the magnetic field source 522 is a permanent magnet, as in self-assembling electrode 150, or if the magnetic field source 522 is an electromagnet, as in self-assembling electrode 250, the magnetic field source 522 can be placed in any different position relative to the EC cell 510. The magnetic field source 522 can be placed in any different position provided the magnetic field causes a material amount of magnetic electrode particles 520 to assemble on the electrode substrate 518 and the multiple inner electrode substrates 519.

[0065] Optionally, the cathode 514 can also be replaced by a self-assembling electrode 550. When both the anode 512 and the cathode 514 are self-assembling electrodes 550, the magnetic field from each self-assembling electrode 550 will be of sufficient intensity to cause a material amount of the magnetic electrode particles 520 to be attracted to and assemble upon the electrode substrates 518 and the multiple inner electrode substrates 519. As described above, the assembly of the magnetic electrode particles 520 on the electrode substrate 518 and the inner electrode substrates 519 builds self-assembling electrodes 550. In this manner, a high surface area, self- assembling electrode will assemble on the outer two electrode substrates 518 and these self-assembling electrodes can act as the anode and cathode. Additionally, the inner electrode substrates 519 will form high surface area self-assembling electrodes that contribute to the formation of the metal hydroxyl ions and hydroxide species.

[0066] Optionally, the multiple inner electrodes can each include a dedicated magnetic field source 522. Each inner electrode substrate 519 can be tube-like, or mesh with a chamber to receive either a permanent magnet or an electromagnet (not shown). Alternatively, the inner electrode substrate 519 is similar to the electrode substrate 318 with the electromagnet integrated into the inner electrode substrate 519 (not shown). In this option, the magnetic field can be removed by removing the permanent magnets from the inner electrode substrate 519 or by turning off the flow of electric current through the electromagnetic circuit of the electromagnets.

[0067] Alternatively, the EC system 500 can be a monopolar arrangement where the inner and outer electrodes form paired electrode stacks 540 with each neighboring electrode (as shown in Figure 5C). Each electrode stack 540 is connected directly to the electric power supply and forms an anode 512 and a cathode 514. This monopolar arrangement may require a resistance box to regulate the flow of current. In the monopolar arrangement, the inner and outer electrodes can be arranged in any of the electrode arrangements, as described above for the bipolar arrangement. Any of the anode 512 and the cathode 514 can be any of the self-assembling electrodes 550.

[0068] Figure 6 depicts a contaminant removal apparatus 600. The contaminant removal apparatus 600 is similar to the apparatus described in the international PCT application CN 1 /001237 entitled "AN APPARATUS AND METHOD FOR ONE STEP REMOVAL OF CONTAMINANTS FROM AN AQUEOUS SYSTEM", which is incorporated herein by reference.

[0069] The contaminant removal apparatus 600 includes an outer cylinder 615, a middle cylinder 610, and an inner cylinder 605. The outer cylinder 615 has a cylindrical upper portion 619 and a generally conical lower portion 621 . The generally conical lower portion 621 terminates as a discharge outlet 660. The contaminant removal apparatus 600 also includes at least one effluent outlet 625 and an overflow outlet 655. These outlets are located near the top of the outer cylinder 615.

[0070] As shown in Figure 7, the contaminant removal apparatus 200 has three chambers. A first chamber 705 is defined by the inner diameter of inner cylinder 605. The second chamber 710 is defined between the outer diameter of inner cylinder 605 and the inner diameter of middle cylinder 610. A third chamber 715 is defined between the inner diameter of the outer cylinder 615 and the outer diameter of the middle cylinder 610.

[0071] The contaminant removal apparatus 600 also includes a removable lid 651 positioned on the top of the outer cylinder 615. The removable lid 651 supports two self-assembling electrodes 650 and a mixing device 641 within the first chamber 705. The self-assembling electrodes 650 are connected to the electric power supply 606. This connection to the electric power supply 606 creates an electric potential between the two self-assembling electrodes 650 completing an electrolytic circuit through the electrolytes present in the contaminated feed water 616. In this manner, the two self- assembling electrodes 650 form an electrode stack 640.

[0072] The self-assembling electrode 650 comprises an electrode substrate 618, magnetic electrode particles 620 and a magnetic field source 622. The electrode substrate 618 can be tube-like or mesh with a chamber to receive the magnetic field source 622. The magnetic field source 622 can be a permanent magnet that passes through holes in the removable lid 651 to introduce or remove the magnetic field source 622 to the first chamber 705. Alternatively, the magnetic field source 622 can be an electromagnet that is inserted into the chamber of an electrode substrate 618 through holes in the removable lid. The magnetic field source 622 can also be an electromagnet that is integrated into the electrode substrate 618.

[0073] Whether integrated or not, the electromagnet has a conducting wire which forms an electromagnetic circuit that is separate from the electrolytic circuit. The electromagnetic circuit can be connected to the electric power supply 606, or not. The flow of electric current through the conducting wire of each electrode substrate 618 creates an electromagnetic field and transforms each electrode substrate 618 into a magnetic field source 622.

[0074] The mixing device 641 has an impeller 646 that is rotated by motor 645. The rotation of the impeller 646 causes axial flow through the inner cylinder 605. The axial flow reduces or prevents fouling of the third self-assembling electrodes 350.

[0075] The contaminant removal apparatus 600 also includes at least one inlet tube 631 . The inlet tube 631 extends through the generally conical lower portion 621 of the contaminant removal apparatus 600 (as shown in Figures 6 and 7). Alternatively, the inlet tube 631 extends through the lid 651 of the contaminant removal apparatus 600 (not shown).

[0076] The contaminated feed water 616 enters the contaminant removal apparatus 600 via the inlet tube 631 . As contaminated feed water 616 enters the contaminant removal apparatus 600, the motor 645 rotates the impeller 646 to produce axial flow of the feed water 616. The magnetic electrode particles 621 can be added to the contaminated feed water 616. The axial force generated by mixing device 641 causes the contaminated feed water 616 and the magnetic electrode particles 620 to flow through the first chamber 605. While the contaminated feed water 616 and the magnetic electrode particles 120 enter the first chamber 605, the magnetic field source 622 attracts the magnetic electrode particles 620 from within the first chamber 605 to the assembly surfaces 624 of the electrode substrate 618 to form the self-assembling electrodes 650.

[0077] After or before, the self-assembling electrodes 650 are formed, the electric power supply 606 establishes a voltage potential between the electrode substrate 618 of each of the self-assembling electrode 650. When this voltage potential is formed, one self- assembling electrode 650 acts as an anode and the other acts a cathode. The anode will produce metal hydroxyl ions and metal hydroxide within the first chamber 305, as described above. The metal hydroxyl ions and metal hydroxide assist with the coagulation of contaminants within the feed water 616. The axial force carries the fluid stream and the coagulates from the first chamber 705 to the second chamber 710, where the coagulates begin to form aggregates that increase in cumulative mass and size. A portion the aggregates can gravitate to the bottom of the outer tube generally conical lower portion 621 . The axial force moves the fluid stream containing the aggregates from the second chamber 710 to the third chamber 715. In the third chamber 715, the aggregates reach a cumulative mass and size such that they gravitate to the bottom of the generally conical lower portion 621 . The clarified fluid exits the effluent outlet 625. The overflow outlet 655 is provided in the event that effluent outlet 625 becomes obstructed. The aggregates are removed from the bottom of the generally conical lower portion 621 through the discharge outlet 660.

[0078] Optionally, the electrode substrates 1 18, 318, 518, 519, 618 can be made of platinum, silver, gold, graphite, a carbon plate, or a conductive metal with a coating that that is insoluble within an electronic field and does not act as a magnetic shield.

[0079] Optionally, the electrode substrate 1 18, 318, 518, 519, 618 can be a mesh structure or a tube-like structure rather than a solid plate structure.

[0080] Optionally, the magnetic electrode particles 120, 520, 620 are made of an iron and aluminum alloy.

[0081] Optionally, the magnetic electrode particles 120, 520, 620 are in a powder form.

[0082] Optionally, the magnetic electrode particles 120, 520, 620 are a rod, needle or shell structure.

[0083] In an additional optional feature of the contaminant removal apparatus 600 includes at least two electrode stacks 640 within the first chamber 705.

[0084] Optionally, the first, second or third self-assembling electrodes 150, 250, 350 can be used in any electrochemical system that would benefit from the features of a high surface area, self-assembling electrodes. For example, electrochemical oxidative and electrocatalytic oxidative systems would benefit from the self-assembly electrodes. Further, an electrochemical oxidative system can use magnetic electrode particles 120 that are iron particles coated with any of the following coating material: Sn0₂, Pb0₂, Sb₂0₅, Ru0₂, Ir0₂, Mn0₂ or other similar compounds.

[0085] In an additional optional feature of the EC system 400, the polarity of the electrode stack 440 is switchable, where the anode 412 and the cathode 414 are replaced by one of the first, second or third self-assembling electrodes 150, 250, 350. The switching of the polarity reverses the electric potential within the electrolytic circuit and can occur during the EC process. The reversal of polarity shares the sacrificial load of the anode 412. Sharing the sacrificial load will decrease the frequency of additional dosing with magnetic electrode particles 120. The polarity reversal within an electrode stack 440 can also improve the symmetry of the current density within the electrode stack 440. Further, the polarity reversal within the electrode stack 440 can facilitate de- fouling of both of the first, second or third self-assembling electrodes 150, 250, 350, regardless of whether a given self-assembling electrode is acting as the anode 412 or the cathode 414.

[0086] In an additional optional feature of the contaminant removal device 600, the inner cylinder 605 of the contaminant removal apparatus 600 is made of a conductive material. In this optional feature of the contaminant removal device 600, the inner cylinder 605 is connected to the electric power supply 606 so that a voltage potential develops between the inner cylinder 605 and the third self-assembling electrodes 350 within the first chamber 705. In this optional feature of the contaminant removal device 600, the electrolytic circuit from the electric power supply 606 is completed between the inner surface of the inner cylinder, through the feed water 616 in the first chamber 705 with each of the self-assembling electrodes 350. Further, the inner cylinder 205 and the self-assembling anodes 155 comprise an electrode stack 640. In this additional optional feature of the contaminant removal device 600, the inner cylinder 605 acts as the cathode and the self-assembling electrodes 650 act as the anode.

[0087] This written description uses examples to disclose the invention, including the best mode, to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art.

Claims

WHAT IS CLAIMED IS:

1. An electrode, comprising: a conductive electrode substrate with an assembly surface; a plurality of magnetic particles; and,

a magnetic field source that attracts at least a portion of the plurality of magnetic particles to contact with the assembly surface.

2. The electrode of claim 1 , wherein the magnetic field source is a permanent magnet or the magnetic field source is an electromagnetic circuit that includes a power source, and a conducting wire, wherein the electromagnetic circuit is external to the electrode substrate or the electromagnetic circuit is integral with the electrode substrate.

3. The electrode of claim 1 , wherein the plurality of fluid magnetic particles are selected from the group consisting of iron, iron-aluminum alloy and coated iron particles.

4. The electrode of claim 3, wherein the coated iron particles are coated with materials selected from the group of Sn0₂, Pb0₂, Sb₂0₅, Ru0₂, Ir0₂ and Mn0₂.

5. The electrode of claim 1 , wherein the conducting wire is a coiled structure.

6. The electrode of claim 5, wherein the coiled structure is wrapped around a ferromagnetic material.

7. The electrode of claim 1 , wherein the conductive electrode substrate is selected from the group of a mesh structure, a tube-like structure and a plate structure.

8. The electrode of claim 1 , wherein the conductive electrode substrate is selected from the group consisting of carbon, titanium, platinum, silver and gold.

9. An electrochemical system, comprising:

a first electrode, wherein the first electrode is a conductive electrode substrate with an assembly surface;

a second electrode;

an electrolyte fluid between the first and second electrodes; a plurality of magnetic particles; a magnetic field source that attracts at least a portion of the plurality of magnetic particles into contact with the assembly surface; and a power source completing a circuit between the first and second electrode.

10. The electrochemical system of claim 9, wherein the magnetic field source is a permanent magnet or the magnetic field source is a first circuit that includes an electric power source, and a conducting wire, wherein the first circuit is external to the electrode substrate or the first circuit is integral with the electrode substrate.

1 1. The electrochemical system of claim 10, wherein the second electrode is a second conductive electrode substrate with a second assembly surface and the magnetic field source attracts at least a portion of the plurality of magnetic particles to assemble the second assembly surface.

12. The electrochemical system of claim 1 1 , further comprising a second magnetic field source, wherein the second magnetic field source is a permanent magnet or the magnetic field source is an third circuit that includes the power source, and a conducting wire, wherein the third circuit is positioned external to the second electrode substrate or the third circuit is integral with the second electrode substrate.

13. The electrochemical system of claim 9, wherein the first electrode and the second electrode are switchable between an anode and a cathode.

14. The electrochemical system of claim 9, further comprising at least one electrode substrate positioned between the first and second electrodes.

15. The electrochemical system of claim 14, each at least one electrode substrate further comprises a magnetic field source.

16. A process for assembling an electrode, comprising

providing a conductive electrode substrate that includes an assembly surface;

providing a plurality of magnetic electrode particles; and establishing a magnetic field that attracts at least a portion of the plurality of fluid magnetic electrode particles into contact with the assembly surface.

17. The process of claim 16, wherein establishing the magnetic field is by a permanent magnet or an electromagnet.

18. The process of claim 16, further comprising disassembling the plurality of fluid magnetic electrode particles from the assembly surface by removing the magnetic field.

19. The process of claim 18, further comprising re-assembling the plurality of fluid magnetic electrode particles to the assembly surface of the conductive electrode substrate by re-establishing the magnetic field.