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
  • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
  • C02F1/505—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment by oligodynamic treatment
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J45/00—Ion-exchange in which a complex or a chelate is formed; Use of material as complex or chelate forming ion-exchangers; Treatment of material for improving the complex or chelate forming ion-exchange properties
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2303/00—Specific treatment goals
  • C02F2303/18—Removal of treatment agents after treatment
  • C02F2303/185—The treatment agent being halogen or a halogenated compound

Definitions

• the field of this invention is the treatment water with silver to disinfect the water and/or remove halide therefrom.
• the invention is particularly concerned with the treatment of drinking water to remove iodide.
• U.S. Patent 2,692,855 discloses using a cation exchange resin in a silver ion form for disinfection of water.
• a cation exchange resin in the hydrogen form may be treated with a solution of a silver salt to exchange silver ions for hydrogen ions, thereby producing a resin for disinfecting water.
• the presence of silver ions in drinking water can be a health hazard, and drinking water contains metal ions that will exchange with the silver ions on the resin.
• the water can first be demineralized by passing it through an cation exchange resin in the hydrogen form to remove metal cations.
• Cation exchangers such as zeolite and synthetic cation exchange resins
• solutions of silver salts to exchange the silver ion for the hydrogen or alkali metal cations of the exchangers.
• Such silver ion-containing resins have been used to remove halides from water, such as the removal of chloride ions from sea water. See United States Patent 3,32,039, United Kingdom Patent 576,969 and Australian Patent 122,647.
• Silver ion-containing cation exchange resins have also been proposed for use in removing iodine and methyl iodide from waste streams, and removing halides from liquid carboxylic acid (U.S. Patent 5,139,981).
• the present invention utilizes a novel resin composition which comprises a chelating resin containing iminodiacetate acid groups at the metal chelating sites, which provide paired acetic acids for chelating action.
• the resin composition is further characterized by containing diacetate chelated silver ions in a ratio of not over 1 silver ion per two iminodiacetate groups.
• the resin is thereby loaded with silver ions to not over 50% of resin capacity.
• the silver ions are thereby retained within the resin beads while effectively killing microorganisms, and/or removing iodide from the water.
• the resulting resin beads tenaciously retain the silver ions and resists their elution by the cations normally found in water, such as hydrogen, sodium, calcium, and magnesium ions.
• the method of this invention also utilizes the retaining capacity of the silver chelating resin composition to minimize the release of silver iodide, silver chloride, or other silver halide into the drinking water.
• the exact mechanism of retention is not fully understood, it has been found that the soluble silver iodide or other silver halide formed within the resin granules or beads are retained therein, resulting in the production of drinking water with minimal content of iodide, silver ion, or silver iodide.
• the method of this invention can be used as a desirable secondary treatment for drinking water which has been contacted with porous granules of a polyiodide anion exchange resin to disinfect the water. Such treatment may release iodide ions into the drinking water.
• the drinking water has initially been disinfected by being contacted with an anion exchange resin containing pentaiodide (I 5 " ) ions.
• an anion exchange resin containing pentaiodide (I 5 " ) ions I 5 " ) ions.
• DETAILED DESCRIPTION For preparing the silver ion containing chelating resin composition, a resin containing iminodiacetate groups is used. Bio-Rad Laboratories, Richmond, CA sells such chelating resins which are polystyrene divinyl benzene copolymers containing iminodiacetate functional groups. These resins are identified as "Chelex 20" (macroporous form) and "Chelex 100" (gel form) . E
• Chelex 100 is available in analytical and biotechnology grades which both are suitable for use in this invention.
• Chelex 20 is a technical grade resin which can also be used.
• the described chelating resin is contacted with an aqueous solution of a silver salt, such as the nitrate, perchlorate, or acetate salts.
• a silver salt such as the nitrate, perchlorate, or acetate salts.
• the hydrogen ions are replaced with the silver ions.
• the silver ions are removed from the solution and immobilized by the paired chelating groups. This conversion to a silver form should be carried out in relation to the stated cation capacity of the resin, viz. in millieqivalents per milliliter.
• the resin composition is prepared so that it does not contain silver ion which easily exchange and/or elute.
• the quantity of silver ions applied to the chelating resin should not exceed one silver ion per two iminodiacetate groups, which corresponds to a 50% or less capacity loading. Stated otherwise, the prepared resin composition should contain not over 0.5 mol of silver per mol of iminodiacetate. Resin compositions can also be used which contain less the stated maximums of silver, such as 0.3 to 0.5 mol of silver per mol of iminodiacetate.
• Chelex 100 a gel-type chelating resin (50-100 mesh or 100-200 mesh, sodium form; Bio-Rad Laboratories, Richmond, CA) is suspended in an excess of distilled water. The settled wet capacity of this resin is 0.40 meg/ml. This resin contains iminodiacetate chelating groups. Total volume is approximately 750 ml of settled bed volume.
• the pH of the aqueous suspension is measured with a standard glass electrode and adjusted with 1.0 N NaOH to at least pH 8.0 if required. Most commercial lots of the resin will generate a suspension with pH >8.0 but an occasional lot may require standardization.
• the supernatant solution is tested with 0.10 M KI solution and produces no silver iodide precipitate.
• the free silver ion concentration of the supernatant solution is undetectable with a silver select ion electrode (Ag + ⁇ lxl0 "6 M) . If more than 0.5 equivalent Ag + :equivalent Chelex resin is used in preparation an extensive washing procedure is required to eliminate the free silver ion in aqueous washes.
• a macroporous chelating resin (20-50 mesh, sodium form; Bio-Rad Laboratories, Richmond, CA) is suspended in an excess of distilled water.
• This resin contains iminodiacetic acid-type chelating groups. Total volume is approximately 500 ml of settled bed volume. (This resin requires only 500 ml to provide 300 meq of binding capacity.)
• the pH of the aqueous suspension is measured with a standard glass electrode and adjusted with 1.0 N NaOH to at least pH 8.0 if required. Most commercially available lots of the resin will generate a suspension with pH >8.0 but the occasional lot requires standardization. This is important to open up both of the acetate groups on the iminodiacetate to accept the silver cation, Ag + .
• a solution of silver nitrate (AgN0 3 ) 150 milli- equivalents (25.48 grams) in 200 ml distilled water is added to the suspended Chelex 20.
• the mixture is stirred with an overhead glass stirring rod to prevent bead fracture. After one hour the stirrer is turned off and the gel allowed to settle.
• the bed volume typically shrinks to 450 ml due to neutralization of the electrorepulsive effects of the adjacent diacetate groups.
• the supernatant solution is tested with 0.10 M KI solu- tion and produces no silver iodide precipitate.
• the free silver ion concentration of the supernatant solution is undetectable with a silver-selective ion electrode (Ag + ⁇ lxl0 "6 M) . If more than 0.5 equivalent Ag + :equivalent Chelex resin is used in preparation an extensive washing procedure is required to eliminate the free silver ion in aqueous washes.
• the iodide anion concentration in the eluates was less than the lowest concentration that could be detected with the iodide-selective electrode (220 millivolts: .00127 ppm).
• the water to be treated is first passed through a quaternary ammonium exchange resin, which as first used has more than sixty-five percent of the ion exchange sites therein associated with pentaiodide ion
• a resin of this kind can be prepared as described in the example of U.S. Patent 4,999,190.
• the resulting resin will have about ninety- seven percent of its total sites iodinated and about seventy percent of the sites will be I 5 " sites.
• the water to be disinfected is first passed through a bed containing granules of this resin. Bacteria and other microorganisms will be killed and the treated water will contain iodide ions (I " ) . To assure complete disinfection and to remove the iodide ions, the initially treated water is passed through one of the silver ion-containing resins prepared as described above.
• the combined treatment will produce bacterially sterile water substantially free of iodide and silver ions.
• activated charcoal may be mixed with the silver chelating resin or used as a tertiary treatment.
• Silver Chelex 20 and 100 resins were prepared as described above containing 0.5 mol of silver ion per mol of iminodiacetate.
• a sulfonic acid resin was loaded with silver ions to 50% capacity and three zeolite exchangers were loaded at less than their maximum capacities. The preparation procedure is described below.
• 50W-X8 a strong cation exchange resin (20-100 mesh, hydrogen form; Bio-Rad Laboratories, Richmond, CA) is suspended in an excess of distilled water. Total volume is approximately 500 ml of settled bed volume.
• a solution of silver nitrate (AgN0 3 ) 150 milliequivalents (25.48 grams) in 200 ml distilled water is added to the suspended AG 50W-X8 resin. (This corresponded to 0.5 mol silver per mol sulfonate.) The mixture is stirred with an overhead glass stirring rod to prevent bead fracture. After one hour the stirrer is turned off and the gel allowed to settle.
• Zeolite cation exchange material (Fisher Chemical Company) was utilized in three commercially available forms which are marketed as molecular sieves; Type 5!, in 1/16 inch pellets; Grade 512, in 4-8 mesh beads; and Grade 513, in 4-8 mesh beads. These zeolites were composed of alumina silicate with either sodium or calcium cations.
• the three zeolites were "converted" to the silver cation form by suspending 100 cm 3 of each material in 100 ml of 0.10 M silver nitrate (AgN0 3 ) solution for 24 hr. at room temperature.
• the total volume of each of the silver nitrate-zeolite preparations was in excess of 150 ml. After overnight reaction some darkening of the solution occurred. After 24 hr. the excess AgN0 3 was decanted and the zeolite washed three times with borosilicate-glass distilled water.

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Pest Control & Pesticides (AREA)
• Plant Pathology (AREA)
• Environmental & Geological Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Agronomy & Crop Science (AREA)
• Inorganic Chemistry (AREA)
• Hydrology & Water Resources (AREA)
• Water Supply & Treatment (AREA)
• Health & Medical Sciences (AREA)
• Dentistry (AREA)
• General Health & Medical Sciences (AREA)
• Wood Science & Technology (AREA)
• Zoology (AREA)
• Environmental Sciences (AREA)
• Treatment Of Water By Ion Exchange (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22784637

Family Applications (1)

Country Status (6)

Families Citing this family (40)

Citations (4)

Family Cites Families (15)

• 1994
  • 1994-03-18 US US08/210,876 patent/US5366636A/en not_active Expired - Fee Related
  • 1994-09-09 US US08/303,368 patent/US5464559A/en not_active Expired - Fee Related
  • 1994-11-01 AU AU10465/95A patent/AU1046595A/en not_active Abandoned
  • 1994-11-01 WO PCT/US1994/012525 patent/WO1995025573A1/en not_active Ceased
  • 1994-11-05 TW TW083110237A patent/TW287147B/zh active
  • 1994-11-11 ZA ZA948966A patent/ZA948966B/xx unknown
  • 1994-11-18 MX MXPA94008982A patent/MXPA94008982A/es not_active Application Discontinuation

Patent Citations (4)

Also Published As

Similar Documents

Legal Events