JPH0254935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Application Field The present invention relates to a method for recycling photographic fixer. SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for reusing waste liquid of a fixer used in developing a silver halide photographic material. b Prior art Silver halide (AgX) remains in addition to the image in a silver halide monochrome photographic light-sensitive material that has been processed with a developer or a silver halide color photographic light-sensitive material that has been processed with a developer and a bleaching solution. . This silver halide is used in the next fixer treatment as AgX+nS ₂ O ^2- ₃ →Ag(S ₂ O ₃ ) ^1-2n _o +X ^- (1) (n is often 2 or 3. X ^- is a halide ion ) is dissolved and removed from the photosensitive material. Due to the reaction (1) above, silver components (silver complex ions) and halide ions accumulate in the drained fixer solution.
Since silver components and halide ions reduce the fixing speed in fixer processing, it is first necessary to remove these components in order to reuse the fixer waste. The electrolytic method is a well-known method for collecting and removing silver components from the waste liquid of the fixing solution, and is already practiced in many photo labs. In this method, for example, the waste fixer solution is poured into an electrolytic cell consisting of a graphite anode and a stainless steel cathode and electrolyzed, thereby electrodepositing metallic silver on the stainless steel cathode. Ion exchange membrane electrodialysis is generally known as a method for removing halide ions from an aqueous solution containing halide ions. However, when ion exchange membrane electrodialysis treatment is applied to the fixer waste liquid after silver recovery electrolysis, the electrical resistance of the ion exchange membrane increases in a short period of time (in the case of constant current operation, the voltage of the dialysis membrane increases).
The electrodialysis tank cannot be operated. In addition, ion-exchange membrane electrodialysis cannot remove colored substances from the fixer waste after silver recovery electrolysis, and if the fixer waste is reused after electrodialysis, it may damage the photosensitive material (film or paper). Stain occurs. c Structure, operation, and effects of the invention The present inventors have developed a case in which the electrical resistance of the ion exchange membrane is prevented from increasing in ion exchange membrane electrodialysis of the fixer waste liquid after the completion of electrolysis, and the waste liquid is reused. The present invention was developed as a result of intensive research into a method for regenerating waste fixer solution that does not stain photosensitive materials. That is, the present invention provides a method for regenerating a photographic fixer, which comprises performing two treatments, an anion exchange resin treatment and an ion exchange membrane electrodialysis treatment, on the waste liquid of the photographic fixer that has been subjected to a silver recovery electrolytic treatment. It is. The photographic fixer of the present invention is an aqueous solution containing sodium thiosulfate or ammonium thiosulfate as a silver halide solubilizing agent. In addition, sodium sulfite, sodium hydrogen sulfite, sodium pyrosulfite, etc. are added to the photographic fixer as an inhibitor of decomposition of the solubilizing agent, and acetic acid, sodium hydroxide, etc. are added as a pH regulator. In addition, potassium aluminium may be added as a hardening agent for a light-sensitive material emulsion, or boric acid or the like may be added as an agent for inhibiting the formation of aluminum hydroxide (precipitate) produced due to potassium aluminium. The method of the present invention will be explained below with reference to the drawings. The figure is a diagram showing a process flow of an embodiment of the method of the present invention. In the figure, 1 is a developing machine for developing silver halide monochrome photographic light-sensitive materials. The photographed monochrome photosensitive material is stored in the developer tank 2, fixer tank 3, washing tank 4, and drying chamber 5 of the developing machine 1.
A photographic image is formed through the process. The fixer waste liquid is sent to an electrolytic cell 7 through a pipeline 6. When a direct current is passed between the cathode 8 and the anode 9 of the electrolytic cell 7, silver is electrodeposited on the cathode 8, and the silver component in the fixer waste is removed. After electrolysis, the fixer is drained through pipeline 1.
0 to the demineralization chamber liquid tank 11. 12 is an adsorption tank. The adsorption tank 12 is filled with an anion exchange resin, and after the electrolysis is completed, the fixing solution waste is circulated from the tank 11 using a circulation pump 13 and circulation pipelines 14 and 15. By this contact treatment with the anion exchange resin, components that increase the electrical resistance of the ion exchange membrane and coloring components contained in the waste fixer after electrolysis are adsorbed and removed. 16 is an ion exchange membrane electrodialysis tank. The electrodialysis tank 16 has a cathode 17 and an anode 18 alternately partitioned by a cation exchange membrane 19 and an anion exchange membrane 20, and has a cathode chamber 21, an anode chamber 22, a plurality of demineralization chambers 23, and a plurality of concentration chambers. A chamber 24 is formed.
After the electrolysis is completed, the fixer is drained from the demineralization chamber liquid tank 11 through the circulation pump 25 and circulation pipelines 26 and 27.
It is circulated to the demineralization chamber 23 of the electrodialysis tank 16. On the other hand, an electrolyte solution (for example, 10 g/aqueous sodium sulfate solution) is circulated from the concentration chamber liquid tank 28 to the cathode chamber 21, anode chamber 22, and concentration chamber 24 of the electrodialysis tank 16 by a circulation pump 29 and circulation pipelines 30, 31. It will be done. When a direct current is passed between the cathode 17 and the anode 18 of the electrodialysis tank 16 in this state, the halide ions in the fixer waste after electrolysis are transferred from the demineralization chamber 23 to the anode chamber 22 and concentration chamber 24 through the anion exchange membrane 20. removed by dialysis. After the above-mentioned contact treatment with the ion-exchange resin and ion-exchange membrane electrodialysis treatment, the waste fixer is transferred from the demineralization chamber liquid tank 11 through the pipeline 32 to the chemical addition tank 33, where it becomes a new fixer. Fixer chemicals 34 are added as shown in FIG. The regenerated fixer prepared in this way is stored in the chemical addition tank 33.
The fixing liquid tank 3 of the developing device 1 is supplied from there through a pump 35 and a pipeline 36. Materials for the cathode 8 in the electrolytic cell 7 include iron, nickel, stainless steel, steel, etc., and materials for the anode 9 include graphite, platinum, platinum-plated titanium, etc. The main body and piping of the electrolytic cell 7 are made of an insulating material such as polyvinyl chloride, rubber, or rubber-lined iron. The current density of the cathode during electrolysis is suitably in the range of 0.05 to 1.0 A/dm ² , although it depends on the silver concentration of the fixer waste and the stirring conditions of the solution. As the material for the adsorption tank 12 and the circulation pipelines 14, 15, polyvinyl chloride is preferred. The adsorption tank is filled with an anion exchange resin. As the anion exchange resin, a strong base type anion exchange resin having a quaternary ammonium group as an exchange group, an anion exchange resin and a weak base type anion exchange resin having a primary to tertiary amine as an exchange group are used. Strong base anion exchange resin adsorbs and removes components (mainly surfactants eluted from photosensitive materials) that increase the electrical resistance of ion exchange membranes (especially anion exchange membranes) contained in the fixer waste after electrolysis. effective. The weakly basic anion exchange resin has the effect of adsorbing and removing coloring components (mainly oxides of developer components that have adhered to the photosensitive material and mixed into the fixer) contained in the fixer waste after electrolysis. The appropriate amount of these anion exchange resins to be used is in the range of 0.1 to 10 milliliters per liter of the fixing solution drained after electrolysis. Materials for the cathode 17 of the ion exchange membrane electrodialysis cell 16 include iron, nickel, stainless steel, etc., and materials for the anode 18 include graphite, platinum, platinum-plated titanium, etc. Cation exchange membrane 1
9 is preferably a strongly acidic cation exchange membrane, and the anion exchange membrane 20 is preferably a strongly basic anion exchange membrane. The main body of the ion-exchange membrane electrodialysis cell 16, the circulation tank, and the piping may be made of insulating materials such as polyvinyl chloride, rubber, or rubber-lined iron. The current density of the ion exchange membrane in ion exchange membrane electrodialysis of the fixer waste after electrolysis is preferably 0.1 to 2.0 A/dm ² . As described above, the present invention is characterized in that, after silver recovery electrolysis is completed, the photographic fixing solution waste is subjected to both an ion exchange membrane electrodialysis treatment and a contact treatment with an anion exchange resin. The reason for this is that coloring substances cannot be removed by ion exchange membrane electrodialysis treatment alone, resulting in staining of the photosensitive material. Furthermore, the electrical resistance of the ion exchange membrane increases in a short period of time, making electrodialysis impossible. Combining ion exchange membrane electrodialysis treatment with anion exchange resin treatment solves the above-mentioned problems and makes it possible to recycle photographic fixer waste. In the present invention, after silver recovery electrolysis is completed, the photographic fixer waste is first treated with an anion exchange resin,
Next, it is preferable to carry out an ion exchange membrane electrodialysis treatment, but both treatments may be carried out in parallel.
Further, the treatment with a strong base type anion exchange resin may be carried out before the electrodialysis treatment, and the treatment with a weak base type anion exchange resin may be carried out after the electrodialysis treatment. A portion of the thiosulfate, sulfite, or bisulfite in the photographic fixer is oxidized during the processing of the light-sensitive material and during silver recovery electrolysis, and sulfate ions are finally produced as by-products. Similar to halide ions, sulfate ions also have the property of reducing the fixing speed, but since they are removed by ion exchange membrane electrodialysis, the fixing speed of the regenerated fixer does not decrease. According to the method of the present invention, components that increase the electrical resistance of the ion exchange membrane in the fixer waste after silver recovery electrolysis are removed, so the ion exchange membrane electrodialysis tank can be used stably for a long period of time. . Furthermore, according to the method of the present invention, components that reduce the fixing speed (halide ions,
Since sulfate ions) and components that cause stains on photographic materials are removed, the waste fixer can be reused repeatedly. The amount of fixer chemicals added to the fixer effluent after the anion exchange resin treatment and ion exchange membrane electrodialysis treatment is much smaller than that in the case of fresh fixer, and the economic advantage of the present invention is great. Furthermore, according to the method of the present invention, the fixing solution is used in a closed system, which solves the problem of environmental pollution caused by drainage. d Examples The method of the present invention will be explained below with reference to Examples. Of course, the method of the present invention is not limited to this. The degree of coloration of the fixer in the examples refers to the absorbance of light with a wavelength of 420 nm, and the fixing ability refers to the time (in seconds) it takes for the film to become transparent after being immersed in the fixer. It has great retention ability. Example: A photographic film for plate making that has been exposed for printing is treated with a monochrome photographic developer and then treated with a new fixer having the composition shown in column (A) of Table 1. silver and silver iodide)
was dissolved and removed. The composition of the fixer waste after the fixing process was as shown in column (B) of Table 1. After the above fixing process, the waste liquid was collected using an electrolytic cell consisting of a rotating cylindrical stainless steel cathode and flat graphite anodes arranged at four locations around the anode, and the cathode current density was
Electrolyzed at 0.25A/ ^dm2 . The composition of the fixer solution drained after the electrolysis was as shown in column (C) of Table 1. After the above electrolysis is completed, the drained fixer solution (200 liters) is transferred to the demineralization chamber liquid tank 11 shown in Fig. 1, and 500 ml of a strong base type anion exchange resin (Amberlite IRA-400 manufactured by Rohm & Hass) and a weak base are transferred. Anion exchange resin treatment was carried out by circulating the mixture into an adsorption tank 12 filled with 200 ml of anion exchange resin (Amberlite IRA-93 manufactured by Rohm & Hass). At the same time, after the above electrolysis is completed, drain the fixer solution as shown in Fig. 116.
Ion exchange membrane electrodialysis, in which the stainless steel cathode 17 and platinum-plated titanium anode 18 are alternately partitioned by 30 strongly acidic cation exchange membranes 19 and 30 strongly basic anion exchange membranes 20, as shown in FIG. It was circulated to the membrane demineralization chamber 23. A 10 g sodium sulfate solution is circulated in the cathode chamber 21, anode chamber 22, and concentration chamber 24, and the current density of the ion exchange membrane is
Electrodialysis was performed by passing a direct current between the cathode and the anode at 1.0 A/dm ² . The cell voltage showed 30V. The composition of the fixer waste after 9 hours of anion exchange resin treatment and electrodialysis treatment was as shown in column (D) of Table 1. After completion of the anion exchange resin treatment and electrodialysis treatment, chemicals in the amounts shown in column (E) of Table 1 were added to the waste fixer solution to prepare the regenerated fixer liquid shown in column (F) of Table 1. . The degree of coloration and fixing ability of the regenerated fixer were exactly the same as the new solution. This regenerated fixer was used for fixing photographic film for plate making, and the photographic properties of the finished photographic film were exactly the same as those of the new fixer (column (A) in Table 1). Also, the above (new solution → fixing treatment → electrolysis → ion exchange resin and electrodialysis treatment → addition of chemicals) → (regeneration solution → fixation treatment → electrolysis → ion exchange resin and electrodialysis treatment → addition of chemicals) → (regeneration solution → When the regeneration system consisting of fixing treatment (→...) was repeated 30 times, the degree of coloration, fixing ability, and photographic properties of the finished film of the regenerated solution were exactly the same as those of the new solution. Furthermore, even after 2000 hours of electrodialysis, the cell voltage of the electrodialysis tank remains
It was the same as when I started dialysis at 30V. In the above-mentioned regeneration system, if the waste fixer solution is subjected to only electrodialysis treatment and no anion exchange resin treatment after electrolysis, the regenerated fixer will be fixed brown, and the film treated with the regenerated fixer will be A yellow stain was formed. Furthermore, after 100 hours of extended operation of the electrodialysis tank, the cell voltage reached 125V, making it impossible to continue electrodialysis. 【table】

[Brief explanation of the drawing]

The figure is a diagram showing a process flow of one embodiment of the present invention. 7 is an electrolytic cell, 12 is an anion exchange resin adsorption tank, and 16 is an ion exchange membrane electrodialysis tank.

Claims (1)

[Scope of Claims] 1. Regeneration of a photographic fixer, characterized in that two treatments, an anion exchange resin treatment and an ion exchange membrane electrodialysis treatment, are performed on the waste liquid of the photographic fixer after silver recovery electrolytic treatment has been completed. Method. 2. The method for regenerating a photographic fixer according to claim 1, wherein a strong base type anion exchange resin and a weak base type anion exchange resin are used as the anion exchange resin.