JPS6010300B2 - How to remove bromide ions from photographic developer - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for removing bromine ions from photographic developers.

The purpose of the present invention is to remove bromide ions accumulated in silver halide photographic developer waste and reuse the waste.
The object of the present invention is to provide a method for efficiently removing bromide ions. Silver halide black-and-white photographic materials undergo a process of constant development, washing, and drying after photographing or print exposure to form a black-and-white image.

Silver halide color photographic materials have slightly different processing methods after exposure, such as photographing or printing, depending on the type, but in principle, a color image is formed through the following processes: color development, bleaching, fixing, washing, and drying. . A developing solution for silver halide photographic materials is generally an aqueous solution containing four components: a developing agent, a preservative, an accelerator, and an inhibitor.

A developing agent is a chemical that has the property of reducing only the port image portion of silver bromide in the emulsion layer of a light-sensitive material and not reducing the rest.
As the developing agent for the developer for black-and-white photographic materials, hydroquine, methyl para-aminophenol sulfate, 1-phenyl-3-pyrazolidone, and the like are used. In addition, as the color developing agent of the color developing solution for color photographic light-sensitive materials, jetyl paraphenylene diamine sulfate, hydroxyethyl ethyl paraphenylene diamine sulfate, 2
-Amino-5-jethylaminotoluene hydrochloride "4-
N.N-dialkyl-p-phenylene such as amino-N-ethyl-N-(3-methanesulfonamidoethyl)-m-toluidine monohydrate and 4-amino-N-hydroxyethyl-N-ethyl-m-toluidine sulfate. Compounds of the diamine family are used. The preservative is a chemical added to prevent the oxidation of the developing agent, such as sodium sulfite, acidic sodium sulfite, isomeric sodium sulfite, or hydroxylamine sulfate. The accelerator is a chemical that strengthens the reducing action of the developing agent, and is an alkali such as sodium hydroxide, an alkaline salt such as sodium carbonate, tribasic sodium phosphate, or borax. The inhibitor is a chemical that strongly suppresses the development of underexposed areas of the silver halide photosensitive material and removes fog, and potassium bromide, sodium bromide, potassium iodide, etc. are used. When the developing agent in the photographic developer reacts with exposed silver bromide in the emulsion layer of the light-sensitive material, a silver image is precipitated in the emulsion layer, and oxidation products and bromide ions are created in the developer. do.

In the case of color development of color photographic materials, the color developing agent oxide combines with the dye coupler in the emulsion layer to form a dye image, but since the color developing agent is susceptible to air oxidation, black and white photographic developers and color Regardless of the color developer used for photography, oxidation products of the developing agent and bromine accumulate in the developer waste, so it is necessary to remove these accumulated substances in order to recycle the developer waste. As a method for removing bromide ions from photographic developer waste, there is a cathode chamber in which the cathode and anode are alternately partitioned by cation exchange membranes and anion exchange membranes, and multiple demineralization chambers (the cathode side is partitioned by a cation exchange membrane). An ion exchange membrane electrodialysis system consisting of a chamber separated by an anion exchange membrane on the anode side, multiple concentration chambers (chamber partitioned on the cathode side by an anion exchange membrane and an anode side by an intestinal ion exchange membrane), and an anode chamber. There is a known method (ion exchange membrane electrodialysis method) in which developer waste is poured into the desalination chamber of the tank, sodium sulfate solution is poured into the concentration chamber, and a direct current is passed between the negative and anode electrodes to perform electrodialysis (ion exchange membrane electrodialysis method). .Miz female awa, A. Sa-saian
d, N. Mii; B mountain retinof the S ratio
ety of Sc3entific Photogr
aphy of Japan, No. 18, 38-44,
In 1968, experimental data were reported regarding the removal of bromide ions from developer waste using an ion exchange membrane with a current density of 0.5 A'd to 2.0 A'd. According to this report, it is possible to remove bromide ions accumulated in developer waste, but the oxidation products of the developer are not removed, so complete regeneration is not possible. The inventor first poured photographic developer waste into the cathode chamber of an electrolytic cell consisting of a cathode chamber and an anode chamber with an anion exchange membrane partitioned between the cathode and anode, and placed an electrolyte such as sodium sulfate in the anode chamber. When the solution is poured and electrolysis is performed, the developing agent product is reduced at the cathode and returns to the developer state, and the bromide ions are removed by moving from the cathode chamber to the anode chamber through the anion exchange membrane, thus regenerating the developer waste solution. He discovered that this was possible and applied for a patent.

They also discovered that it was possible to regenerate developer waste by combining the cathodic reduction method of the developer's oxidation product with the aforementioned ion-exchange membrane electrodialysis method, and filed a patent application. However, when the present inventor conducted continuous operation for removing bromide ions from photographic developer waste using ion-exchange membrane electrodialysis, the electrical resistance of the ion-exchange membrane increased with the number of days of operation.
The bromide removal rate of the ion exchange membrane decreased with the number of operating days.

Additionally, pinholes and cracks appeared in the anion exchange membrane, making continuous operation impossible. As a result of intensive research into a method that solves the above-mentioned problems in removing bromide ions from photographic developer waste using ion-exchange membrane electrodialysis and enables efficient continuous operation, the inventor discovered the following new facts (5 items). ) and arrived at the present invention. ■ The electrical density of the anion exchange membrane is o. Below 0 secretion/d, the bromide removal rate of the anion exchange membrane is too low to be practical.

■ When the electrical density of the anion exchange membrane becomes 0.02 A/d or higher, the bromide ion removal rate increases, but at 0.1 A/d.
Above d, the bromide ion removal rate decreases.

■ Change the current density of the anion exchange membrane to 0.02 to 0.1 orbit/
When continuous operation is performed while maintaining the d in the range, no increase in the electrical resistance of the ion exchange membrane is observed, and no decrease over time in the bromide ion removal rate of the anion exchange membrane is observed.

(2) If the electrical density of the anion exchange membrane is maintained at 0.1 axis/d force or higher and the operation is continued, the electrical resistance of the ion exchange membrane increases over time, and the bromide removal rate of the anion exchange membrane decreases over time.

(2) When the electrical density of the anion exchange membrane exceeds 0.2 I/d force, pinholes or cracks are likely to occur in the exchange membrane.

That is, the present invention reduces the current density of an anion exchange membrane to o. 02~o. This is a method for removing bromine ions from a photographic developer, which is characterized by maintaining the bromine ions at 1 y/d.

The ion exchange membrane electrodialysis method of the present invention includes a cathode chamber in which the cathode and anode are alternately partitioned by cation exchange membranes and anion exchange membranes, a plurality of demineralization chambers (the cathode side is a cation exchange membrane,
An ion exchange membrane electrodialysis tank consisting of a chamber (chamber partitioned by an anion exchange membrane on the anode side), multiple concentration chambers (chamber partitioned by an anion exchange membrane on the cathode side and a cation exchange membrane on the anode side), and an anode chamber. A method of removing bromide ions from the developer waste by pouring an electrolyte solution such as a sodium sulfate solution into the cathode, concentration, and anode chambers and passing a direct current between the negative and anode electrodes. It is.

In addition, the waste developer is poured into the cathode chamber of an electrolytic cell consisting of a cathode chamber and an anode chamber, in which the anode and cathode are separated by an anion exchange membrane, and an electrolyte solution such as a sodium sulfate solution is poured into the anode chamber. The ion exchange membrane electrodialysis method also includes a method of removing bromide ions from the waste developer solution by passing a direct current between the steps. The above electrodialysis tank. Iron, nickel, lead, zinc, stainless steel, etc. are used as the material for the cathode of the electrolytic cell.
Furthermore, examples of the material for the anode include platinum, platinum-plated titanium, and graphite.

The anion exchange membrane is preferably a strongly basic type, and the cation exchange membrane is preferably a strongly acidic type. The electrolyte solutions poured into the cathode chamber, concentration chamber, and anode chamber of the electrodialysis tank and the anode chamber of the electrolytic cell include alkaline solutions such as sodium hydroxide solution or potassium hydroxide solution, salt solutions such as sodium sulfate solution, and sulfuric acid. Acid solutions such as

A concentration of these electrolyte solutions of 0.1 to 2 normal is sufficient. As mentioned above, when performing continuous operation to remove bromide ions from developer waste using an ion exchange membrane electrodialyzer or an ion exchange membrane electrolyzer, the current density of the anion exchange membrane is 0.
．． Below 0, the removal rate of bromide ions is too low to be practical.

As the current density of the anion exchange membrane increases, the bromide ion removal rate also increases, but when the current density exceeds 0.1 d/d, the bromide ion removal rate decreases, and the current density If it exceeds 0.1 d, the electrical resistance of the ion exchange membrane increases over time and the bromide removal rate decreases over time. Furthermore, if the current density exceeds 0.25 A'd, pinholes or cracks are likely to occur in the anion exchange membrane. According to the method of the present invention, when bromide ions in photographic developer waste are removed by ion-exchange membrane electrodialysis, the ion-exchange membrane electrodialysis does not increase over time nor does the bromide ion removal rate decrease over time, making it highly efficient. Continuous operation is possible.

In addition, by keeping the membrane current density below 0.1 insects/d〆, wasted electricity for removing bromide ions can be saved, and pinholes and cracks are less likely to occur in the exchange membrane, making operation easier and extending the life of the membrane. also increases. In this way, when bromide ions in photographic and developer waste are continuously removed by ion exchange membrane electrodialysis, why is the exchange membrane current density much smaller than the conventionally known anion exchange membrane current density effective? Although the details of this effect are not clear, it is thought to be due to the special cause of photographic developing solutions in which developing agents and preservatives are dissolved.

When recycling photographic developer waste using the method of the present invention, the developer waste is stored in the cathode chamber of an electrolytic cell consisting of a cathode chamber and an anode chamber with an anion exchange membrane separating the cathode and anode. The ion exchange membrane electrodialysis method according to the present invention is used in combination with a cathodic reduction method of the oxidized product of the developing agent, in which an electrolyte solution such as sodium sulfate is poured into the anode chamber to carry out electrolysis.

Or, the cathode of an ion exchange membrane dialysis tank consisting of a cathode chamber, multiple concentration chambers, multiple desalination chambers, and an anode chamber in which the cathode and anode are alternately partitioned by an anion exchange membrane and an intestinal ion exchange membrane. A photographic developer waste solution is poured into the chamber and the desalination chamber, and the solution is circulated between the cathode chamber and the desalination chamber, and an electrolyte solution such as sodium sulfate is poured into the concentration chamber and the anode chamber. A direct current may be passed between the negative and anode electrodes so that the current density is 0.02 to 0.15 A/d, so that the cathodic reduction of the oxidation product of the developing agent in the developer waste solution and the removal of bromide ions from the waste solution may be carried out. Alternatively, the ion-exchange membrane electrodialysis method according to the present invention may be combined with, for example, a method for selectively removing the oxidized product of the developing agent using a chemical adsorbent or the like. The method of the present invention will be explained below with reference to Examples.

Of course, the content of the present invention is not limited to this. In the examples, the removal rate of bromine ions (T'd〆・H
) is the value calculated using the following formula. Removal rate of bromide ions (in/d/H) = amount of developer waste (x {pre-dialysis bromine ions (in/d) - post-dialysis bromine ions (in/in)} anion exchange membrane area (in d) x Time) Example 1 A color developer having the composition shown in Table 1, column A was supplied to the color developer chamber of a color film developing machine to develop a color film.

The color developer waste solution (column B in Table 1) discharged from the color developer chamber is transferred to a strong acid cation exchange membrane with 2 prongs and a strong base anion exchange membrane with 2 prongs between the stainless steel cathode and the platinum-plated titanium anode. Alternately partitioned with exchange membranes. 1 cathode chamber, 2
0 desalination chambers (chambers separated by a cation exchange membrane on the cathode side and an anion exchange membrane on the anode side), 1 concentration chamber (separated by an anion exchange membrane on the cathode side and a cation exchange membrane on the anode side) The sodium sulfate solution is supplied to the cathode chamber and demineralization chamber of the ion exchange membrane electrodialysis tank, which consists of one anode chamber) and one anode chamber, and the sodium sulfate aqueous solution is supplied to the concentration chamber and the anode chamber for 30 minutes to connect the anode and negative electrodes. It was operated continuously for a long period of time using direct current.

During continuous operation, make sure that the bromide ion concentration of the dialysis developer flowing out from the demineralization chamber of the ion exchange membrane electrodialysis tank is the same as the bromide ion concentration (0.01 t/t) listed in column A of Table 1. Although the amount of color developer waste solution supplied was adjusted, the effects of the current density of the anion exchange membrane on the time-dependent changes in cell voltage and the time-dependent changes in bromide ion removal rate are shown in Tables 2 and 3, respectively. It can be seen from Tables 2 and 3 that the anion exchange membrane current density within the claimed range gives the most favorable results for continuous operation.

Table 1: Composition Table 2: Tank voltage (V) Table 3: Bromine ion removal rate (T) The Kafu vapor was developed by supplying it to a chamber.

The color developer waste liquid discharged from the color developer chamber (Table 4, column B) is supplied to the desalination chamber of the ion exchange membrane electrodialysis tank described in ~ Example 1, and the cathode chamber, concentration chamber, and anode chamber are A continuous operation was carried out for a long time by supplying an aqueous sodium sulfate solution of 30% and passing a direct current between the negative and positive electrodes. During continuous operation, the bromide ion concentration of the dialysis developer solution flowing out from the cathode chamber and demineralization chamber of the ion exchange membrane electrodialysis tank becomes the same as the bromide ion concentration (0.10 t/s) listed in column A of Table 4. Tables 5 and 6 show the effects of the current density of the anion exchange membrane on the voltage change over time and the bromide ion removal rate over time, respectively.

It can be seen from Tables 5 and 6 that the anion exchange membrane current density within the claimed range gives the most favorable results for continuous operation.

Table 4 Composition Table 5 Voltage (V) Table 6 Bromine removal rate (Taso d H)
Example 3 A developer having the composition shown in column A of Table 7 was supplied to the developer chamber of a black and white photographic film developing machine to develop a black and white photographic film.

The developer waste solution discharged from the developer chamber (column B in Table 7) is supplied to the cathode chamber and demineralization chamber (binary chamber) of the ion exchange membrane electrodialysis tank described in Example 1, and Waste developer solution was circulated between the salt chambers. Thirty tons of the sodium sulfate aqueous solution was supplied to the concentration chamber and the anode chamber, and continuous operation was carried out for a long period of time by passing a direct current between the negative and anode electrodes. During continuous operation, the bromide ion concentration of the dialysis developer solution flowing out from the cathode chamber and demineralization chamber of the ion exchange membrane electrodialysis tank becomes the same as the bromide ion concentration (0.1 t/s) listed in column A of Table 7. Tables 8 and 9 show the influence of the anion exchange membrane current density on the change in cell voltage and the rate of bromide ion removal over time, respectively.

It can be seen from Tables 8 and 9 that the anion exchange membrane current density within the claimed range gives the most favorable results for continuous operation.

In addition, when the current density of the anion exchange membrane is 0.04 A/d and 0.1 'd〆, chemicals are added to the developing solution after dialysis to make it the same as the composition in column A of Table 7, and a black and white film is prepared. When used for development, the photographic properties were normal.

Table 7 Composition Table 8 Cell voltage (V)

Claims (1)

[Claims] 1. When removing bromide ions in a photographic developer by ion exchange membrane electrodialysis, the electrolyte density of the anion exchange membrane must be maintained at 0.02 to 0.15 A/dm^2. A method for removing bromide ions from a photographic developer, characterized by: 2. A photographic developing chamber filled with a demineralization chamber in which the cathode and anode are alternately partitioned by cation exchange membranes and anion exchange membranes, with the cation exchange membrane on the cathode side and the anion exchange membrane on the anode side. The bromide ion removal method according to claim 1, characterized in that the solution is subjected to electrodialysis.