WO2012159206A1 - Cellules électrolytiques et procédés pour minimiser la formation de dépôts sur des électrodes de diamant - Google Patents

Cellules électrolytiques et procédés pour minimiser la formation de dépôts sur des électrodes de diamant Download PDF

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Publication number
WO2012159206A1
WO2012159206A1 PCT/CA2012/000503 CA2012000503W WO2012159206A1 WO 2012159206 A1 WO2012159206 A1 WO 2012159206A1 CA 2012000503 W CA2012000503 W CA 2012000503W WO 2012159206 A1 WO2012159206 A1 WO 2012159206A1
Authority
WO
WIPO (PCT)
Prior art keywords
cell
electrodes
electrochemical cell
deposits
polarity
Prior art date
Application number
PCT/CA2012/000503
Other languages
English (en)
Inventor
Thomas Urbanek
Original Assignee
Klaris Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Klaris Corporation filed Critical Klaris Corporation
Publication of WO2012159206A1 publication Critical patent/WO2012159206A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46119—Cleaning the electrodes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46133—Electrodes characterised by the material
    • C02F2001/46138—Electrodes comprising a substrate and a coating
    • C02F2001/46147—Diamond coating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/007—Contaminated open waterways, rivers, lakes or ponds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/008—Originating from marine vessels, ships and boats, e.g. bilge water or ballast water
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
    • C02F2103/023—Water in cooling circuits
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/42—Nature of the water, waste water, sewage or sludge to be treated from bathing facilities, e.g. swimming pools
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus
    • C02F2201/46105—Details relating to the electrolytic devices
    • C02F2201/46115—Electrolytic cell with membranes or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus
    • C02F2201/46105—Details relating to the electrolytic devices
    • C02F2201/4612—Controlling or monitoring
    • C02F2201/46125—Electrical variables
    • C02F2201/4613—Inversing polarity

Definitions

  • the present invention relates to methods to minimize the build-up of deposits, particularly scale, on doped diamond electrodes.
  • US patent 4,789,448 to Woodhouse discloses a device comprising a sacrificial anode that releases a salt into the electrolyte.
  • the salt forces scale-forming solutes to precipitate from the electrolyte.
  • the formation of scale on electrodes is reduced.
  • the present invention relates in a particular embodiment to operating doped diamond electrodes in contact with an electrolyte comprising at least one substance that can form deposits, such as scale, on said electrodes.
  • At least one electrode of the electrolytic cell comprises nanocrystalline doped diamond; other electrodes of the cell may comprise any material suited to meet the requirements of the intended application.
  • deposits on diamond electrodes are removed by reversing the polarity of the electrical potential from time to time.
  • the process of removing deposits is significantly improved.
  • FIG. 1 Microcrystalline diamond electrodes, water supply: Ottawa drinking water, flow rate: 20cm/s, electrode area: 3cm 2 , electrode spacing: 0.2cm, current density: 200mA/cm 2 , frequency of polarity reversals: 4/hr, power supply/recorder: Solartron 1287.
  • Nanocrystalline diamond electrodes water supply: Ottawa drinking water, flow rate: 20cm/s, electrode area: 3cm 2 , electrode spacing: 0.2cm, current density: 200mA/cm 2 , frequency of polarity reversals: 4/hr, power supply/recorder: Solartron Figure 3.
  • Nanocrystalline diamond electrodes Water supply: Calgary drinking water, flow rates: 1 l cm/s and 19cm/s, square electrode, electrode area: 9cm 2 , electrode spacing: 0.1cm, current density: 170mA/cm 2 , power supply: Lambda GEN 40-38.
  • Nanocrystalline diamond electrodes Water supply: Calgary drinking water, added salt: sodium chloride, flow rate: 1 lcm/s, square electrode, electrode area: 9cm 2 , electrode spacing: 0.1cm, current density: 170m A/cm 2 , power supply: Lambda GEN 40-38.
  • 'hardness of water' or 'hard water' are commonly defined as water containing a concentration of multivalent cations, and water containing a higher concentration of these cations is considered harder.
  • Multivalent cations are ions with a charge greater than +1 , such as calcium and magnesium ions.
  • Minerals comprising multivalent cations can deposit on electrodes, and the deposits are commonly referred to as scale. Other deposits, for example, may comprise biofilms or polymers that form via electropolymerization processes.
  • Electrodes comprising doped diamond are commonly referred to as diamond electrodes. Most diamond electrodes comprise microcrystalline doped diamond with a nominal grain size above ⁇ ⁇ . More recently nanocrystalline doped diamond electrodes were developed. Nanocrystalline doped diamond is commonly defined by having a nominal grain size of less than 100 nm, for example 100, 90, 80, 70, 60 nm, etc., and more preferably less than 50 nm, for example 50, 40, 30, 20, 10, 5 nm, etc. Diamond electrodes have unique properties, such as a wide potential window, and high chemical and physical stabilities. These properties make diamond electrodes eminently suited for synthetic and analytical processes. The high oxygen
  • overpotential of the electrodes permits the efficient generation of strong oxidants, such as hydroxyl radicals, ozone, persulfates, and hypochlorites in aqueous media.
  • US patent 7,309,441 to Rychen et al. discloses the use of diamond electrodes to treat water supplies that form aerosols and, thereby, are liable to spread Legionella bacteria. Specifically cited are the treatment of water in air conditioners, hot water supplies, circulation baths, ornamental waterscapes, cooling towers, and other processes where water is recirculated.
  • polarity reversals could be used to remove the deposits, in particular from diamond electrodes. Over extended periods, however, polarity reversals are generally not sufficient to remove all scale from microcrystalline diamond electrodes. Since the performance of the electrodes deteriorates with the formation of scale, the use of more elaborate cleaning methods eventually becomes necessary. Such methods may involve taking the electrolytic cell and electrode array apart, treating the electrodes with acid, and reassembling the entire device.
  • Figures 1 and 2 depict the performance of microcrystalline and nanocrystalline doped diamond electrodes under galvanostatic conditions in hard water.
  • the floating electrical potential rises as deposits build up on both types of diamond electrodes.
  • the polarity of the electrical potential is reversed to remove formed deposits. With the removal of deposits, the electrical potential required to maintain a specific current drops and establishes new minimum.
  • the floating electrical potential applied to the nanocrystalline diamond electrodes always reverts quickly back to the original minima, indicating a
  • deposits may form during the treatment of chemical and biological contaminants, specifically disinfection and sterilization processes, deodortzation and decolourization processes, the removal of ions from electrolytes, the electrochemical generation of oxidants, such as hydroxyl radicals, ozone, hypochlorites, persulfates, percarbonates, perborates, chlorine dioxide, and others, the syntheses of short-lived or stable chemicals, or combinations of these processes.
  • oxidants such as hydroxyl radicals, ozone, hypochlorites, persulfates, percarbonates, perborates, chlorine dioxide, and others, the syntheses of short-lived or stable chemicals, or combinations of these processes.
  • the anodes and cathodes of an electrolytic cell comprise nanocrystalline doped diamond.
  • This embodiment is particularly useful as it may (a) permit the removal of formed deposits with the least interruption of ongoing electrochemical processes, (b) eliminate the cross-contamination of reaction products with other electrode materials, (c) extend the longevity of an electrolytic cell, (d) extend the interval between maintenance cycles of the electrolytic cell, and (e) permit the use of the electrolytic cell under more aggressive operating conditions.
  • At least one electrode of an electrolytic cell comprises nanocrystalline doped diamond.
  • Other electrodes of the electrolytic cell may comprise any suitable material, such as steel, stainless steel, tungsten, carbon, platinum, gold, a conductive ceramic, and others. This embodiment may be useful, for instance, to reduce the cost of the electrolytic cell or to perform electrochemical reactions that other electrodes are better suited for.
  • scale may form on cathodes comprising other materials. The scale may be removed through polarity reversals. For the period that the diamond electrodes operate as cathodes, deposits, such as scale, may form on them. If microcrystalline diamond electrodes were used, the removal of formed deposits may require more elaborate cleaning processes than polarity reversals alone.
  • Electrodes of the disclosed electrolytic cell may have any suitable shape, dimension, numerical ratio, polarity, and spatial arrangement relative to each other.
  • the electrolytic cells may also be divided or undivided, and may comprise ion-conductive membranes that are placed between the electrodes of the device.
  • Electrical potentials applied to the disclosed electrolytic cell may range from 1 to 1 15 Volt, for example, but not limited to 1 , 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 1 10, 1 15 Volt, or any value therein between, but more preferably from 1 to 40 Volt, for example, but not limited to 1, 2, 3, 5, 7, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 Volt, or any value therein between. Except for using polarity reversals, the electrolytic cell may arbitrarily be operated under potentiostatic or galvanostatic conditions, and others. Comninellis et al.
  • the floating electrical potential then depends on operating conditions, such as the electrical resistance of the cell, electrolyte, and ongoing physical and chemical processes and may vary over a wide range before and after the occurrence of polarity reversals. When operated under potentiostatic conditions, the electrical potentials may be adjusted to any arbitrary value, and their numerical values may be kept identical or dissimilar before and after polarity reversals. The floating electrical current then depends on the operating conditions and may vary over a wide range before and after the occurrence of polarity reversals.
  • the process of reversing the polarity of the electrical potential may be performed manually, automatically after certain intervals, or automatically triggered when the floating electrical potential or current reaches a preset value.
  • the frequency of the polarity reversals may be adjusted according to the rate at which deposits on the electrodes are formed and may vary from seconds and minutes, to hours and many days, for example, but not limited to 1 , 5, 10, 20, 30, 45, 60 seconds, 1.5, 2, 2.5, 5, 10, 15, 20, 30, 40, 45, 50, 60 minutes, 1.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12 hours, 1 , 2, 3, 4, 5, 6, 7 days, and the like.
  • the duration of the polarity reversal may also occur for a similar time period as described above.
  • nanocrystalline diamond electrodes include, but are not limited to, laminar or turbulent flows of the electrolyte over the electrodes, continuous or intermittent streams of gas bubbles contacting the electrodes, baffles, Venturis, or static mixers, and various combinations thereof.
  • Figures 3 to 5 show that the electrical potential increases at lower rates, and less deposits are formed, when salt concentrations or flow rates are higher, and when current densities are lower.
  • Electrolytic cells comprising diamond electrodes were powered by a device that converts 120 VAC to a DC output in the range of 12 to 40VDC and provides constant currents, which can be preset to an arbitrary value between 5 and 20A.
  • the power supply was also capable of reversing the polarity of the voltage applied to the electrodes after preset time periods ranging from 0.5 to 60 minutes. Before each polarity reversal and for a preset period, the potential was kept at zero. During this period the electrolytic cell, which acts as a capacitor, was allowed to discharge. If the external load were to exceed 20A, the power supply voltage would fold back for protection. The power supply would resume its normal operating condition when the overload or short condition was removed. All of the cited functions were provided automatically.
  • the power supply started up by applying a normal polarity and a constant electrical current to the electrodes for a preset period.
  • the electrical potential was allowed to float within preset limits, and it increased as deposits on the electrodes were formed.
  • the electrical potential was kept at zero for a preset period.
  • the polarity was reversed and a constant electrical current flowed in the opposite direction for a preset period.
  • another period followed where the electrical potential was set to zero for a preset period.
  • the cycle began again. Any of the time periods may be chosen as equal in length to previous periods, but they may also be different, and the electrical currents may also be equal or different before and after polarity reversals.
  • FIG. 6 shows the performance of the power supply in dependence of time. Shown are two 30s intervals before polarity reversals during which no voltage is applied to the electrodes.
  • a polarity reverser may change the polarity when it senses that a preset limit of the floating electrical potential or current is reached. This embodiment works on the principal that the potential increases or that the electrical current decreases as deposits are formed. Thus, it is possible to monitor these changes and to reverse the polarity when a preset limit is reached, or the like.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)

Abstract

L'invention concerne des cellules électrolytiques et des procédés pour minimiser la formation de dépôts sur des électrodes de diamant, en particulier des électrodes de diamant nanocristallin dopées.
PCT/CA2012/000503 2011-05-25 2012-05-25 Cellules électrolytiques et procédés pour minimiser la formation de dépôts sur des électrodes de diamant WO2012159206A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA2740759A CA2740759A1 (fr) 2011-05-25 2011-05-25 Cellules electrolytiques et procedes pour minimiser la formation de depots sur electrodes a diamant
CA2,740,759 2011-05-25

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WO2012159206A1 true WO2012159206A1 (fr) 2012-11-29

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104611759A (zh) * 2015-02-12 2015-05-13 广州市精源电子设备有限公司 变极性脉冲酸洗控制方法
DE102015111103A1 (de) 2014-07-23 2016-01-28 Innovatec Gerätetechnik Gmbh Elektrolysezelle und Verfahren zum Betreiben einer Elektrolysezelle

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110869323A (zh) * 2017-07-12 2020-03-06 安克信水技术公司 操作废水处理系统的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5062940A (en) * 1988-03-02 1991-11-05 Water Regeneration Systems, Inc. Electrolytic liquid purification apparatus
CA2703093A1 (fr) * 2007-10-25 2009-04-30 Sumitomo Electric Hardmetal Corp. Electrode en diamant, dispositif de traitement et procede de production d'une electrode en diamant
US7534296B2 (en) * 2002-01-11 2009-05-19 Board Of Trustees Of Michigan State University Electrically conductive diamond electrodes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5062940A (en) * 1988-03-02 1991-11-05 Water Regeneration Systems, Inc. Electrolytic liquid purification apparatus
US7534296B2 (en) * 2002-01-11 2009-05-19 Board Of Trustees Of Michigan State University Electrically conductive diamond electrodes
CA2703093A1 (fr) * 2007-10-25 2009-04-30 Sumitomo Electric Hardmetal Corp. Electrode en diamant, dispositif de traitement et procede de production d'une electrode en diamant

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102015111103A1 (de) 2014-07-23 2016-01-28 Innovatec Gerätetechnik Gmbh Elektrolysezelle und Verfahren zum Betreiben einer Elektrolysezelle
CN104611759A (zh) * 2015-02-12 2015-05-13 广州市精源电子设备有限公司 变极性脉冲酸洗控制方法

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