US2944895A - Regeneration of photographic silver bleach solutions - Google Patents
Regeneration of photographic silver bleach solutions Download PDFInfo
- Publication number
- US2944895A US2944895A US501188A US50118855A US2944895A US 2944895 A US2944895 A US 2944895A US 501188 A US501188 A US 501188A US 50118855 A US50118855 A US 50118855A US 2944895 A US2944895 A US 2944895A
- Authority
- US
- United States
- Prior art keywords
- solution
- bleach
- bleaching
- bromide
- spent
- 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.)
- Expired - Lifetime
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- 239000007844 bleaching agent Substances 0.000 title claims description 28
- 229910052709 silver Inorganic materials 0.000 title claims description 14
- 239000004332 silver Substances 0.000 title claims description 14
- 238000011069 regeneration method Methods 0.000 title description 10
- 230000008929 regeneration Effects 0.000 title description 9
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title description 8
- 238000004061 bleaching Methods 0.000 claims description 25
- YAGKRVSRTSUGEY-UHFFFAOYSA-N ferricyanide Chemical compound [Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] YAGKRVSRTSUGEY-UHFFFAOYSA-N 0.000 claims description 17
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 claims description 17
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 11
- -1 SILVER HALIDE Chemical class 0.000 claims description 10
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 claims description 7
- 239000000839 emulsion Substances 0.000 claims description 7
- 229910001513 alkali metal bromide Inorganic materials 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 3
- 150000001340 alkali metals Chemical class 0.000 claims 1
- UETZVSHORCDDTH-UHFFFAOYSA-N iron(2+);hexacyanide Chemical compound [Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] UETZVSHORCDDTH-UHFFFAOYSA-N 0.000 claims 1
- 239000000243 solution Substances 0.000 description 49
- 238000000034 method Methods 0.000 description 7
- 230000001172 regenerating effect Effects 0.000 description 5
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 4
- 230000003716 rejuvenation Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910021538 borax Inorganic materials 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 229910001622 calcium bromide Inorganic materials 0.000 description 1
- WGEFECGEFUFIQW-UHFFFAOYSA-L calcium dibromide Chemical compound [Ca+2].[Br-].[Br-] WGEFECGEFUFIQW-UHFFFAOYSA-L 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000000276 potassium ferrocyanide Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- ADZWSOLPGZMUMY-UHFFFAOYSA-M silver bromide Chemical compound [Ag]Br ADZWSOLPGZMUMY-UHFFFAOYSA-M 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000004328 sodium tetraborate Substances 0.000 description 1
- 235000010339 sodium tetraborate Nutrition 0.000 description 1
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- XOGGUFAVLNCTRS-UHFFFAOYSA-N tetrapotassium;iron(2+);hexacyanide Chemical compound [K+].[K+].[K+].[K+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] XOGGUFAVLNCTRS-UHFFFAOYSA-N 0.000 description 1
- DCXPBOFGQPCWJY-UHFFFAOYSA-N trisodium;iron(3+);hexacyanide Chemical compound [Na+].[Na+].[Na+].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] DCXPBOFGQPCWJY-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
- G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
- G03C5/395—Regeneration of photographic processing agents other than developers; Replenishers therefor
- G03C5/3952—Chemical, mechanical or thermal methods, e.g. oxidation, precipitation, centrifugation
Definitions
- a commonly employed silver bleaching solution consists essentially of an aqueous solution of an alkali ferricyanide and an alkali bromide with possibly other chemicals added.
- the use of these solutions for bleaching developed photographic emulsions depletes both the ferricyanide and the halide ion therein. The efiiciency of the bleaching solution diminishes upon continued use and, therefore, regeneration thereof would be desirable after each use.
- spent ferricyanide type silver bleach solutions may be regenerated in a time on the order of 30 minutes at usual temperatures by the use of the water soluble persulfates over a wide pH range such as pH 3-10.
- the presence of persulfates, even in excess, does not impair the bleaching action of ferricyanide type bleaching solutions and is not harmful to the photographic material processed therewith.
- spent ferricyanide type bleach solutions may be rapidly rejuvenated in this manner, with only a build up of sulfate ion therein which, when desired, can be readily removed by the addition of calcium chloride without any undue loss in concentration of the active constituent therein, except possibly as the voluminous precipitate formed may entrap a certain amount of bleaching reagents.
- Our invention involves the use as the regenerating agent of a water soluble persulfate such as of ammonium,
- ammonium persulfate although the pH of the bleach solution is decreased the decomposition product thereof is more soluble and, therefore, ammonium persulfate is quite useful in the repeated rejuvenation of the bleach bath.
- the persulfate added to the spent bleach solution quantitatively oxidizes any ferrocyanide therein to ferricyanide and with the addition of further alkali metal bromide and additional ferrocyanide, if desired, the bath may be brought to a composition which is substantially as effective for bleaching purposes as the original bleaching solution.
- the spent bleaching solution which resulted had the following composition per liter; Na Fe(CN) .l0H O, 9.2 grams; Na Fe(CN) 12.9 grams; NaBr, 4.75 grams.
- Our invention is also useful in preparing fresh bleach initially starting with ferrocyanide and persulf ate together with the addition of'alkali metal bromide thereto.
- the processing of developed silver halide photographic emulsion layers which comprises treating said layers with a bleach solution containing analkali metal ferricyanide and an alkali metal bromide, adding'to the spent bleaching solution which results a water-soluble persulfate in an amount approximately chemically equivalent to the ferrocyanide present in the spent liquor plus sodium bromide in suflicient amount to restore the bromide content of the bleach solution and bleaching further 7 developed silver halide photographic emulsion layers with the regenerated bleach solution thus obtained.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
Description
REGENERATION 9F PHOTOGRAPHIC SHJVER BLEACH SOLUTIONS Lloyd E. West, Rochester, and Bernard A. Hutchins,
Livonia, N.Y., assignors to Eastman Kodak Company,
Rochester, N.Y., a corporation of New Jersey .NoDrawing. Filed Apr. 13, 1955, Ser. No. 501,188 '3 Claims. (Cl. 96--60) This invention relates to the regeneration of spent photographio silver bleach solutions with water-soluble persulfates.
In the processing of color film and in many black and white photographic processes the silver which forms upon developing is converted into a hypo-soluble silver salt which is subsequently removed by fixing. A commonly employed silver bleaching solution consists essentially of an aqueous solution of an alkali ferricyanide and an alkali bromide with possibly other chemicals added. The use of these solutions for bleaching developed photographic emulsions depletes both the ferricyanide and the halide ion therein. The efiiciency of the bleaching solution diminishes upon continued use and, therefore, regeneration thereof would be desirable after each use.
The prior art has suggested regeneration of bleach solutions with alkali metal bromates but the expense involved in that method makes it somewhat questionable whether or not regeneration offers anything over bleach solutions newly prepared. Electrolytic rejuvenation methods have also been disclosed but there are objections thereto such as the high capital investment necessary, high maintenance costs and the formation of sludge in bleach solutions treated in this manner.
One object of our invention is to provide a method for regenerating exhausted spent silver bleach solutions, characterized by the ease of operation and the practical nature thereof. Another object of our invention is to provide a method for regenerating spent bleach solutions in which the products incorporated in the solution as a result of the regeneration do not exhibit any elfects deleterious to its value in processing photographic products. A further object of our invention is to provide a method for regenerating bleach solutions which imparts the desired efiect thereto rapidly and under mild conditions. Other objects of our invention will appear herein.
We have found that spent ferricyanide type silver bleach solutions may be regenerated in a time on the order of 30 minutes at usual temperatures by the use of the water soluble persulfates over a wide pH range such as pH 3-10. We have found that the presence of persulfates, even in excess, does not impair the bleaching action of ferricyanide type bleaching solutions and is not harmful to the photographic material processed therewith. We have found that spent ferricyanide type bleach solutions may be rapidly rejuvenated in this manner, with only a build up of sulfate ion therein which, when desired, can be readily removed by the addition of calcium chloride without any undue loss in concentration of the active constituent therein, except possibly as the voluminous precipitate formed may entrap a certain amount of bleaching reagents.
Our invention involves the use as the regenerating agent of a water soluble persulfate such as of ammonium,
sodium or potassium in an amount at least chemically equivalent to the ferrocyanide formed upon use of the bleaching solution. The addition of an excess of the persulfate to the solution not only does not interfere cyanide present particularly where pH control is im-' portant.
Because the conversion of silver to silver bromide in the bleaching operation reduces the bromide content of the bleaching solution, it is usually desirable to also add sodium bromide, to the spent bleaching solution in sulficient amount to bring the bromide content thereof up to that desired. Sometimes it may be desirable to supply additional ferrocyanide to the spent bleaching bath to restore the ferricyanide content'to approximately that originally present. In a typical regeneration procedure the content of potassium ferrocyanide is diminished by conversion to ferricyanide after the addition of potassium persulfate to the spent bleaching solution as illustrated in the following table:
rejuvenated by our procedure in which a water soluble persulfate is added up to the point where the sulfate salt which results therefrom reaches its saturation equilibrium in the solution. This is not apt to be reached under actual conditions. However, if this point is reached the sulfate ion content may be removed by the addition of calcium chloride or calcium bromide thereby precipitating calcium sulfate without seriously altering the concentrations of the active constituent except as the precipitate carries down with it some of the ferrocyanide or ferricyanide which is present in the solution. We have found that potassium persulfate is probably more convenient to use as the regenerating agent primarily because of its low cost and availability. In the case of ammonium persulfate although the pH of the bleach solution is decreased the decomposition product thereof is more soluble and, therefore, ammonium persulfate is quite useful in the repeated rejuvenation of the bleach bath. The persulfate added to the spent bleach solution quantitatively oxidizes any ferrocyanide therein to ferricyanide and with the addition of further alkali metal bromide and additional ferrocyanide, if desired, the bath may be brought to a composition which is substantially as effective for bleaching purposes as the original bleaching solution.
The following example illustrates the regeneration of a spent bleaching solution in accordance with our invention:
A photographic bleach solution having the following formula: Na Fe(CN) .10H- O, 1 gram; Na Fe('CN) 23 grams; NaBr, 7.5 grams; water to make 1 liter, which bath had a pH of 8.3 was employed to bleach a quantity of color developed print material. The spent bleaching solution which resulted had the following composition per liter; Na Fe(CN) .l0H O, 9.2 grams; Na Fe(CN) 12.9 grams; NaBr, 4.75 grams. By calculation it became apparent that a of the following quantities Patented July 12, I960 g f .t 2,944,895
would be needed to restore the spent bleaching solutio to its original strength per liter of solution:
Na Fe (CN) IOH O 8. 9-grams; K S 4.84 grams;-NaBr, 2.75 grams. The
until solution was complete. The mass was allowed tostand for 1 or 2 hours and where desirable, the solution was filtered. The regenerated bleach was then analyzed for ferrocyanide and ferricyanide content and if the pH value was critical that was determined also. When the ferricyanide content was below that required, amounts of ferrocyanide andpersulfate were additionally added to bring the concentration to the desired point; Experience indicates that it is desirable to use'a slight excess of the persulfate and the ferrocyanide to obtain the desired ferricyanide concentration because of the increase in volume upon addition of the chemicals. When the pH of the bleach is critical this value may be adjusted by the addition of an appropriate chemical such as sodium hydroxide, borax or boric acid.- After the spent bleach solution had been regenerated to bring the contents of ferricyanide and sodium bromide to approximately those of the original solution, further developed print material was processed therewith. It was found that the bleaching efiectiveness of the regenerated solution was substantially equivalent to that of the original bleach solution.
Our invention is also useful in preparing fresh bleach initially starting with ferrocyanide and persulf ate together with the addition of'alkali metal bromide thereto.
It is to be understood that we do: not wish" to be limited to the specific embodiment described herein except as defined. by the appended claims We claim:
1. The processing of developed silver halide photographic emulsion layers which comprises treating said layers with a bleach solution containing analkali metal ferricyanide and an alkali metal bromide, adding'to the spent bleaching solution which results a water-soluble persulfate in an amount approximately chemically equivalent to the ferrocyanide present in the spent liquor plus sodium bromide in suflicient amount to restore the bromide content of the bleach solution and bleaching further 7 developed silver halide photographic emulsion layers with the regenerated bleach solution thus obtained.
2. The processing of developed silver halide photographic emulsion layers which comprises treating said layers with a bleach solution containing an alkali metal ferricyanide and an alkali metal bromide, whereby a spent bleaching solution is obtained in which ferricyanide is reduced to ferroc'yanide, followed by adding to the spent bleaching solution a water-soluble persul'fate in amount approximately chemically equivalent to the ferrocyanide therein and an alkali metal bromide in sufficient amount to substantially restore the original bromide content of the bleached solution.
3'. The processing of developed: .silver halide photographic emulsion layers which comprises treating said layers with a bleach solution containing sodium ferricyanide and sodium bromide, whereby the ferricyanide of the solution is reduced to ferrocyanide, followed by adding to the spent bleaching solution potassium persulfate in an amount approximately chemically. equivalent to the ferrocyanide present in the spent solution and sodium bromide in a sufliicient amount to substantially restore the original bromide content of the bleached solution.
Theoretical Chemistry, vol. 10, page 467.
General Chemistry, Pauling, 1947, pages 184-185.
Disclaimer 2,944,895.LZog 0Z E. W est, Rochester and Bernard A. Hutchins, Livonia, N.Y. REGENERATION OF PHOTOGRAPHIC SILVER BLEACH SOLUTIONS. Patent dated July 12, 1960. Disclaimer filed Aug. 26, 1974, by the assignee, Eastman Kodak Company.
Hereby disclaims the entire remaining portion of the term of said patent.
[Oyficial Gazette April 29, 1975.]
Claims (1)
1. THE PROCESSING OF DEVELOPED SILVER HALIDE PHOTOGRAPHIC EMULSION LAYERS WHICH COMPRISES TREATING SAID LAYERS WITH A BLEACH SOLUTION CONTAINING AN ALKALI METAL FERRICYANIDE AND AN ALKALI METAL BROMIDE, ADDING TO THE SPENT BLEACHING SOLUTION WHICH RESULTS A WATER-SOLUBLE PERSULFATE IN AN AMOUNT APPROXIMATELY CHEMICALLY EQUIVALENT TO THE FERROCYANIDE PRESENT IN THE SPENT LIQUOR PLUS SODIUM BROMIDE IN SUFFICIENT AMOUNT TO RESTORE THE BROMIDE CONTENT OF THE BLEACH SOLUTION AND BLEACHING FURTHER DEVELOPED SILVER HALIDE PHOTOGRAPHIC EMULSION LAYERS WITH THE REGENERATED BLEACH SOLUTION THUS OBTAINED.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US501188A US2944895A (en) | 1955-04-13 | 1955-04-13 | Regeneration of photographic silver bleach solutions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US501188A US2944895A (en) | 1955-04-13 | 1955-04-13 | Regeneration of photographic silver bleach solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2944895A true US2944895A (en) | 1960-07-12 |
Family
ID=23992462
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US501188A Expired - Lifetime US2944895A (en) | 1955-04-13 | 1955-04-13 | Regeneration of photographic silver bleach solutions |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2944895A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50101027A (en) * | 1974-01-08 | 1975-08-11 | ||
| US3909403A (en) * | 1972-10-23 | 1975-09-30 | Fuji Photo Film Co Ltd | Process of treating waste water |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2135872A (en) * | 1934-05-24 | 1938-11-08 | Frederick Post Company | Development of exposed blueprint sheets |
| US2189264A (en) * | 1936-12-04 | 1940-02-06 | Keuffel & Esser Co | Ferroprussiate photoreproduction |
| US2515930A (en) * | 1946-05-04 | 1950-07-18 | Pavelle Color Inc | Regeneration of photographic silver bleach solution |
| US2611699A (en) * | 1949-12-30 | 1952-09-23 | Gen Aniline & Film Corp | Regeneration of exhausted silver bleaching solutions |
-
1955
- 1955-04-13 US US501188A patent/US2944895A/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2135872A (en) * | 1934-05-24 | 1938-11-08 | Frederick Post Company | Development of exposed blueprint sheets |
| US2189264A (en) * | 1936-12-04 | 1940-02-06 | Keuffel & Esser Co | Ferroprussiate photoreproduction |
| US2515930A (en) * | 1946-05-04 | 1950-07-18 | Pavelle Color Inc | Regeneration of photographic silver bleach solution |
| US2611699A (en) * | 1949-12-30 | 1952-09-23 | Gen Aniline & Film Corp | Regeneration of exhausted silver bleaching solutions |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3909403A (en) * | 1972-10-23 | 1975-09-30 | Fuji Photo Film Co Ltd | Process of treating waste water |
| JPS50101027A (en) * | 1974-01-08 | 1975-08-11 |
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