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WO1996034999A1 - Bromide removal - Google Patents

Bromide removal Download PDF

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Publication number
WO1996034999A1
WO1996034999A1 PCT/US1995/005603 US9505603W WO9634999A1 WO 1996034999 A1 WO1996034999 A1 WO 1996034999A1 US 9505603 W US9505603 W US 9505603W WO 9634999 A1 WO9634999 A1 WO 9634999A1
Authority
WO
WIPO (PCT)
Prior art keywords
brine
electrolyser
filter
bromide
sodium hypochlorite
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/US1995/005603
Other languages
French (fr)
Inventor
David Macdonald Bonnick
Roger Roydon Ford
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Filter Wallace and Tiernan Inc
Original Assignee
Wallace and Tiernan Inc
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
Priority claimed from GB939322625A external-priority patent/GB9322625D0/en
Priority to GB9421964A priority Critical patent/GB2283484B/en
Application filed by Wallace and Tiernan Inc filed Critical Wallace and Tiernan Inc
Priority to MX9708504A priority patent/MX9708504A/en
Priority to CA002220112A priority patent/CA2220112C/en
Priority to PCT/US1995/005603 priority patent/WO1996034999A1/en
Priority to US08/973,078 priority patent/US6428677B1/en
Priority to AU24351/95A priority patent/AU702950B2/en
Publication of WO1996034999A1 publication Critical patent/WO1996034999A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B11/00—Oxides or oxyacids of halogens; Salts thereof
    • C01B11/20—Oxygen compounds of bromine
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/09—Bromine; Hydrogen bromide
    • C01B7/096—Bromine
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/14—Purification
    • C01D3/16—Purification by precipitation or adsorption
    • 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
    • C02F1/4674—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation with halogen or compound of halogens, e.g. chlorine, bromine
    • 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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/24—Halogens or compounds thereof
    • C25B1/26—Chlorine; Compounds thereof

Definitions

  • the present invention relates to a method and apparatus for removing bromide from an electrolytic chlorination system. It is well known to produce sodium hypochlorite from sodium chloride brine by converting the brine to sodium hypochlorite in an electrolyser. Sodium hypochlorite is used to treat potable water. Unfortunately, if the brine includes traces of bromide, the electrolyser causes the conversion of the bromide by oxidation to bromate. It is desirable to produce bromate-free sodium hypochlorite for the treatment of potable water as experiments have indicated that bromate may be carcinogenic. It is an object of the present invention to provide a method and apparatus for removing bromide from an electrolytic chlorination system so as to obviate or mitigate the problem outlined above.
  • a method for removing bromide from an electrolytic chlorination system in which brine is converted to sodium hypochlorite in an electrolyser, wherein the brine is fed to the electrolyser through a filter containing a medium capable of adsorbing bromine or hypobromous acid, and sodium hypochlorite is fed back from the electrolyser and mixed with the brine feed upstream of the filter to oxidize any bromide in the brine to bromine or hypobromous acid.
  • the present invention also provides an electrolyser for converting brine to sodium hypochlorite, means for feeding brine to the electrolyser, a filter through which the brine is fed to the electrolyser, the filter being capable of adsorbing bromine or hypobromous acid, and means for mixing sodium hypochlorite from the electrolyser with the brine upstream of the filter such that bromide in the brine is oxidized to bromine or hypobromous acid.
  • hydrochloric acid is mixed with the brine upstream of the filter to maintain a low pH and thereby ensure effective oxidation of the bromide.
  • the illustrated electrolytic chlorination system comprises a salt saturator 1 in which brine is prepared.
  • the saturator 1 may have a capacity of, for example, 15 cubic meters.
  • Brine flows from the saturator 1 through a filter 2 to an electrolyser 3, the brine flow being maintained by a brine transfer pump 4.
  • a flow rate through the pump 4 of 51.5 liters per hour may be established.
  • the electrolyser 3 is of conventional form and is effective to oxidize the brine to sodium hypochlorite.
  • the contents of the electrolyser are mixed with dilution water supplied through line 5 at a rate of 540 liters per hour, the resultant sodium hypochlorite being transferred to a product tank 6 with a capacity of 13 cubic meters.
  • sodium hypochlorite from the product tank 6 is fed back through line 8 to a point upstream of the filter 2.
  • the flow of hypochlorite is maintained by a hypochlorite transfer pump 9.
  • Hydrochloric acid is also delivered to the brine flow upstream of the filter 2 via line 10, the flow of hydrochloric acid being maintained by a pump 11.
  • the flow of sodium hypochlorite was 1 liter per hour and the flow of hydrochloric acid was 1 liter per hour.
  • the supply of hydrochloric acid is controlled to maintain a low pH in the brine flow upstream of the filter 2. Typically the acidity will be controlled to approximately 4 pH.
  • bromide in the brine flow is rapidly converted into bromine and hypobromous acid which is adsorbed by the filter 2.
  • the filter is capable of adsorbing bromine or bromine released by the reduction of hypobromous acid, substantially no bromine compounds reach the electrolyser and accordingly substantially no bromate reaches the product tank 8.
  • Appropriate materials for the filter 2 are activated carbon zeolites and insoluble reducing agents, for example calcium sulphite.

Landscapes

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

Abstract

A chlorination system in which brine is converted to sodium hypochlorite by an electrolyser. Brine (1) fed to the electrolyser (3) is passed through a filter (2) which is capable of adsorbing bromine or hypobromous acid. Some of the sodium hypochlorite produced in an electrolyser (3) is fed back to a point in the brine feed upstream of the filter (2) such that any bromide in the brine is oxidized to bromine or hypobromous acid and therefore adsorbed by the filter (2).

Description

BROMIDE REMOVAL
The present invention relates to a method and apparatus for removing bromide from an electrolytic chlorination system. It is well known to produce sodium hypochlorite from sodium chloride brine by converting the brine to sodium hypochlorite in an electrolyser. Sodium hypochlorite is used to treat potable water. Unfortunately, if the brine includes traces of bromide, the electrolyser causes the conversion of the bromide by oxidation to bromate. It is desirable to produce bromate-free sodium hypochlorite for the treatment of potable water as experiments have indicated that bromate may be carcinogenic. It is an object of the present invention to provide a method and apparatus for removing bromide from an electrolytic chlorination system so as to obviate or mitigate the problem outlined above.
According to the present invention, there is provided a method for removing bromide from an electrolytic chlorination system in which brine is converted to sodium hypochlorite in an electrolyser, wherein the brine is fed to the electrolyser through a filter containing a medium capable of adsorbing bromine or hypobromous acid, and sodium hypochlorite is fed back from the electrolyser and mixed with the brine feed upstream of the filter to oxidize any bromide in the brine to bromine or hypobromous acid.
The present invention also provides an electrolyser for converting brine to sodium hypochlorite, means for feeding brine to the electrolyser, a filter through which the brine is fed to the electrolyser, the filter being capable of adsorbing bromine or hypobromous acid, and means for mixing sodium hypochlorite from the electrolyser with the brine upstream of the filter such that bromide in the brine is oxidized to bromine or hypobromous acid. Preferably hydrochloric acid is mixed with the brine upstream of the filter to maintain a low pH and thereby ensure effective oxidation of the bromide.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing which illustrates a bromide removal system incorporated into a conventional on-site electrolytic chlorination system.
The illustrated electrolytic chlorination system comprises a salt saturator 1 in which brine is prepared. The saturator 1 may have a capacity of, for example, 15 cubic meters. Brine flows from the saturator 1 through a filter 2 to an electrolyser 3, the brine flow being maintained by a brine transfer pump 4. A flow rate through the pump 4 of 51.5 liters per hour may be established. The electrolyser 3 is of conventional form and is effective to oxidize the brine to sodium hypochlorite. The contents of the electrolyser are mixed with dilution water supplied through line 5 at a rate of 540 liters per hour, the resultant sodium hypochlorite being transferred to a product tank 6 with a capacity of 13 cubic meters.
With the exception of the filter 2, the components shown in the drawing and described above are entirely conventional. With the operation of such a conventional system, however, traces of bromide in the brine flow are converted to bromate and reach the product tank 6. This is undesirable as the content of the product tank 6 is delivered via line 7 to a treatment plant (not shown) in which the contents of the product's tank is mixed with a supply of potable water.
In accordance with the present invention, sodium hypochlorite from the product tank 6 is fed back through line 8 to a point upstream of the filter 2. The flow of hypochlorite is maintained by a hypochlorite transfer pump 9. Hydrochloric acid is also delivered to the brine flow upstream of the filter 2 via line 10, the flow of hydrochloric acid being maintained by a pump 11. In the illustrated system the flow of sodium hypochlorite was 1 liter per hour and the flow of hydrochloric acid was 1 liter per hour. The supply of hydrochloric acid is controlled to maintain a low pH in the brine flow upstream of the filter 2. Typically the acidity will be controlled to approximately 4 pH. At such a low pH, bromide in the brine flow is rapidly converted into bromine and hypobromous acid which is adsorbed by the filter 2. By appropriate selection of the stoichiometry and reaction time the further oxidization of the hypobromous acid to bromate can be minimized or substantially eliminated. Accordingly, providing the filter is capable of adsorbing bromine or bromine released by the reduction of hypobromous acid, substantially no bromine compounds reach the electrolyser and accordingly substantially no bromate reaches the product tank 8.
Appropriate materials for the filter 2 are activated carbon zeolites and insoluble reducing agents, for example calcium sulphite.

Claims

1. A method for removing bromide from an electrolytic chlorination system in which brine is converted to sodium hypochlorite in an electrolyser, wherein the brine is fed to the electrolyser through a filter containing a medium capable of adsorbing bromine or hypobromous acid, and sodium hypochlorite is fed back from the electrolyser and mixed with the brine feed upstream of the filter to oxidize any bromide in the brine to bromine or hypobromous acid.
2. A method according to Claim 1, wherein hydrochloric acid is mixed with the brine feed upstream of the filter to maintain a low pH and thereby ensure effective oxidation of the bromide.
3. An electrolytic chlorination system comprising an electrolyser for converting brine to sodium hypochlorite, means for feeding brine to the electrolyser, a filter through which the brine is fed to the electrolyser, the filter being capable of adsorbing bromine or hypobromous acid, and means for mixing sodium hypochlorite from the electrolyser with the brine upstream of the filter such that bromide in the brine is oxidized to bromine or hypobromous acid.
4. An apparatus according to Claim 3, comprising means for mixing the brine upstream of the filter with hydrochloric acid to maintain a low pH and thereby ensure effective oxidation of the bromide.
5. A method for removing bromide from an electrolytic chlorination system substantially as hereinbefore described with reference to the accompanying drawing.
6. An electrolytic chlorination system substantially as hereinbefore described with reference to the accompanying drawing.
PCT/US1995/005603 1993-11-03 1995-05-04 Bromide removal Ceased WO1996034999A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
GB9421964A GB2283484B (en) 1993-11-03 1994-10-28 Bromide removal
MX9708504A MX9708504A (en) 1995-05-04 1995-05-04 Bromide removal.
CA002220112A CA2220112C (en) 1993-11-03 1995-05-04 Bromide removal
PCT/US1995/005603 WO1996034999A1 (en) 1993-11-03 1995-05-04 Bromide removal
US08/973,078 US6428677B1 (en) 1995-05-04 1995-05-04 Bromide removal
AU24351/95A AU702950B2 (en) 1995-05-04 1995-05-04 Bromide removal

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB939322625A GB9322625D0 (en) 1993-11-03 1993-11-03 Bromide removal
CA002220112A CA2220112C (en) 1993-11-03 1995-05-04 Bromide removal
PCT/US1995/005603 WO1996034999A1 (en) 1993-11-03 1995-05-04 Bromide removal

Publications (1)

Publication Number Publication Date
WO1996034999A1 true WO1996034999A1 (en) 1996-11-07

Family

ID=27170521

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/005603 Ceased WO1996034999A1 (en) 1993-11-03 1995-05-04 Bromide removal

Country Status (3)

Country Link
CA (1) CA2220112C (en)
GB (1) GB2283484B (en)
WO (1) WO1996034999A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113753861A (en) * 2021-09-29 2021-12-07 山东海王化工股份有限公司 Method for producing sodium bromate by combining alkaline process bromine extraction and diaphragm-free electrolysis

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2348195A (en) * 1999-03-24 2000-09-27 Ion Enterprises Ltd Fluid treatment
DE50102673D1 (en) * 2001-05-16 2004-07-29 Va Tech Wabag Deutschland Gmbh Method and device for removing bromide from water
DE102008041164B4 (en) 2008-08-11 2011-01-13 Werthmann, Christine, Dr. Process for the treatment of water

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB867790A (en) * 1958-04-03 1961-05-10 Donald Edward Ferris Method and apparatus for producing hypochlorite of soda in an electrolytic cell
US3909377A (en) * 1971-12-14 1975-09-30 Rhone Poulenc Sa Purification of a chloride solution
FR2388597A1 (en) * 1977-04-27 1978-11-24 Sorapec Electrolytic cell with no separator between the electrodes - partic. useful for eliminating pollutants from effluents

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB867790A (en) * 1958-04-03 1961-05-10 Donald Edward Ferris Method and apparatus for producing hypochlorite of soda in an electrolytic cell
US3909377A (en) * 1971-12-14 1975-09-30 Rhone Poulenc Sa Purification of a chloride solution
FR2388597A1 (en) * 1977-04-27 1978-11-24 Sorapec Electrolytic cell with no separator between the electrodes - partic. useful for eliminating pollutants from effluents

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113753861A (en) * 2021-09-29 2021-12-07 山东海王化工股份有限公司 Method for producing sodium bromate by combining alkaline process bromine extraction and diaphragm-free electrolysis
CN113753861B (en) * 2021-09-29 2022-10-18 山东海王化工股份有限公司 Method for producing sodium bromate by combining alkaline process bromine extraction and diaphragm-free electrolysis

Also Published As

Publication number Publication date
CA2220112A1 (en) 1996-11-07
CA2220112C (en) 2007-02-27
GB2283484A (en) 1995-05-10
GB9421964D0 (en) 1994-12-21
GB2283484B (en) 1997-07-30

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