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
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
  • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
  • C02F1/766—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens by means of halogens other than chlorine or of halogenated compounds containing halogen other than chlorine
• • 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
  • B01J41/00—Anion exchange; Use of material as anion exchangers; Treatment of material for improving the anion exchange properties
  • B01J41/04—Processes using organic exchangers
  • B01J41/07—Processes using organic exchangers in the weakly basic form
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/16—Nitrogen compounds, e.g. ammonia
  • C02F2101/18—Cyanides
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/20—Heavy metals or heavy metal compounds
  • C02F2101/203—Iron or iron compound

Definitions

• ABSTRACT In a process of removing ferricyanide ions and/or fcrrocyanide ions from a waste solution or water containing these ions formed in photographic processings by bringing the waste solution in Contact with a weaklybasie anion-exchange resin to absorb the ferricyanide ions and/or ferrocyanide ions on the anion-exchange resin, an alkaline concentrate of the tcrricyanide ions and/or ferrocyanide ions is formed by immersing the weakly-basic anion-exchange resin having absorbed thereon the ions and after adding to the concentrate a strong alkali, a hypochlorite, and bromide ions to increase the pH of the concentrate to above 12, the mixture is heated to temperatures over 50C at normal pressure, whereby the ferricyanide i
• the present invention relates to a process of treating waste water containing ferricyanide ions and/or ferrocyanide ions. More particularly, the. invention relates to a process of treating waste water containing ferricyanide ions and/or ferrocyanide ions from photographic processings. 1
• rocyanide ions such as a waste solution in galvanizing or printing and a waste solution used for the syntheses of dyes, pigments, etc., as an oxidizing agent.
• the processing steps for photographic materials include frequently a bleach step.
• the bleach step is a step in which a metal such as silver formed by development is converted into silver ions using an oxidizing agent and the bleach step is included usually in the processings of silver halide color photographic materials on photographic materials for the silver dye bleach method as well as in the reduction processings of photographic materials for making printing plates.
• the reduction operation as described above is the step of oxidizing the metallic silver formed by development into silver ions and dissolving the silver ions.
• the reduction operation is conducted, when the image density of a photographic material becomes higher than an appropriate value after developrnent caused by excessive light exposure, to reduce the image density to the appropriate range oris conducted to control the properties of the dot imagesof a photographic printing plate formed by developing .a photographic material for making .a printing plate. 5
• the waste water from the reduction step contains ferricyanide ions and/or ferrocyanide ions, which are there duction products of the ferricyanide ions, together with I the thiosulfate.
• the ferricyanide ions and/or the ferrocyanide ions are quite stable complex ions having almost no toxicity but it is known that when'those ions are subjected to photochemical oxidation, they are decomposed to form toxic free cyanides (see, e.-g:., Yu Yiu Lurc and V. A. Panova; Behavior of Cyano Compounds in Water Ponds, Gidrokhim; Materialy, 31133-143 (1964), and George Edgar and Morris Lipschuets; Toxicity of Ferroand Ferricyanide Solutions to Fish and Determination of the Cause of Mortality, Trans. Am. Fish $00., 78,192 (1948)).
• theallowable limit in Japan for the amount of cyanide is one ppm.
• the ferricyanide ions and/or ferrocyanide ions have the latent toxicity as described above and hence the aforesaid standard is as a matter of course applied to those ions as well. Therefore, it is necessaray to take some counteraction in the case of discharging waste water containing those ions.
• the concentration of the ferricyanide ions and/or ferrocyanide ions in the waste water from the reduction step using farmers reducer is fairly low because a large amount of water is used for washing in the reduction step but the concentration is nevertheless higher than the discharge standard as indicated above: Furthermore, sincelfree cyanide formed by the photochemical decomposition of ferricyanide ions and/or ferrocyanide ions is quite high in toxicity as mentioned above, the ferricyanide ions and/or ferrocyanide ions present even in a considerably low concentration must be removed.
• the process of removing ferricyanide ions and/or ferrocyanide ions by precipitation as the result of the reaction with an iron salt utilizes the phenomenon of the formation by these ions of Prussian Blue by the reaction with iron salt ions (see, Japanese Pat. application
• this process has the disadvantage that a long time is required to precipitate the particles of Prussian Blue since the particles are very fine and, in particular, when the waste solution to 'be treated is low in concentration and contains a large amount of water such as the waste water from the reduction step or waste water of the reducer, the process requires equipment with a large capacity.
• This process has further the disadvantage that since the precipitates formed contain ferricyanide and/or ferrocyanide, they may not be discharged as they are and hence must be treated further.
• Electrodialysis and reverse osmosis may be effective processes for treating waste water containing ferricyaamount of water such as the waste water from the reduction step,-'-a" verylargeequipment is requiredand hence the cost for the equipment is quite high.
• the combustion process is a process of evaporating water and decomposing the residue unde'r'heating to a high temperature by means of a heavy oil. burner, etc.
• the pyrolysis process is a process wherein a strong alkali is added to the solution containing the ferricyanide ions and/or ferrocyanide ions to adjust the pH of the solution over 12 and after heating the solution to temperatures over 50C at normal pressure, a hypochlorite is added thereto to decompose by oxidation the ferricyanide ions and/or the ferrocyanide ions contained in the solution (Japanese Pat. application No. 50,932/1971).
• the ferricyanide ions and/or ferrocyanide ions are decomposed into iron oxide, carbon dioxide, carbonate, nitrogen and ammonia.
• the advantage of this process is that, in contrast to the process of pre cipitating or concentrating ferricyanide ions and/or ferrocyanide ions, such as the process of precipitating utilizing the reaction with an iron salt, a reverse osmosis process, and an electrodialysis process, the ferricyanide ions and/or ferrocyanide ions are completely decomposed into innocuous components and hence this process is a complete final treatment eliminating the necessity of further treatment.
• the waste reducer solution contains a large amount of water, the process requires also a large amount' of heat and large scale equipment as in the case of the combustion process. Furthermore, since the waste reducer solution contains a thiosulfate, the hypochlorite added to decompose by oxidation the ferricyanide ions and/or ferrocyanide ions is readily reduced by the thiosulfate thereby losing its oxidative power.
• ferricyanide ions and/or ferrocyanide ions in a waste solution containing these ions in low concentration by the aforesaid pyrolysis process is a quite expensive.
• the ferricyanide ions and/or ferrocyanide ions treated by this ion-exchange process are still in the form of ferricyanide and/or ferrocyanide ions and thus the problem of pollution occurs in discharging such residues.
• the ionexchange process has the disadvantage that it is not a complete final treatment for the waste solution.
• An object of this invention is, therefore, to provide an economical and complete treatment process for removing efficiently ferricyanide ions and/or ferrocyanide ions from waste water or a solution containing the ferricyanide ions and/or ferrocyanide ions together with thiosulfate ions in an innocuous dischargeable form.
• This invention provides a process of treating waste water containing ferricyanide ions and/or ferrocyanide ions which comprises bringing the waste water containing these ions in contact with a weakly-basic anionexchange resin, removing the weakly-basic anionexchange resin having adsorbed thereon the ions from the waste water, immersing the weakly-basic anionexchange resin having the ions adsorbed thereon in an alkaline solution to provide an alkaline concentrated solution of the ions, adding to the concentrated solution a strong alkali, a hypochlorite, and bromide ions to adjust the pH of the solution to above 12, and heating the mixture to temperatures above C at normal pressure, whereby the ferricyanide ions and/or the ferrocyanide ions are decomposed.
• a process of treating waste water containing ferricyanide ions and/or ferrocyanide ions which comprise bringing the waste water contain ing the ions in contact with a weakly basic anionexchange resin in the presence of at least one of borate ions, a weak acid, and a weak acid salt, removing the weakly-basic anion-exchange resin having adsorbed thereon the ions from the waste water, immersing the weakly-basic anion-exchange resin having the ions adsorbed thereon in an alkaline solution to provide an alkaline concentrated solution of the ions, adding to this solution a strong alkali, a hypochlorite, and bromide ions to adjust the pH of the solution to above 12, and heating the mixture to temperatures above 50C, whereby the ferricyanide ions and/or the ferrocyanide ions are decomposed.
• the inventors have further investigated the pyrolysis of ferricyanide ions and/or the ferrocyanide ions and have discovered that the presence of bromide ions is necessary for completely decomposing the ferricyanide ions and/or ferrocyanide ions into innocuous materials. Namely, the inventors have conducted the pyrolysis of a solution containing ferricyanide ions and/or ferrocyanide ions for investigating the pyrolysis of waste reducer solution and have confirmed that l to 10% by weight of the ferricyanide ions and/or ferrocyanide ions always remain in the treated solution, in other words, the decomposition reaction in the pyrolysis is not complete.
• the inventors have also investigated the influence of various materials on the pyrolysis when they are present in the pyrolysis system and as the results thereof, have discovered that ferricyanide ions and/or ferrocyanide ions are completely decomposed by the pyrolysis only when bromide ions are prsent in the pyrolysis system,
• the inventors have developed a complete decomposition treatment of ferricyanide ions and/or ferrocyanide ions as an economical and final treatment for waste water containing ferricyanide ions and/or ferrocyanide ions together with thiosulfate ions, by combining the treatment of the waste water with a weakly-basic anion-exchange resin and the pyrolysis of a concentrated solution of ferricyanide ions and/or ferrocyanide ions in the presence of bromide ions.
• the process of this invention is an excellent complete treatment for such'waste water.
• the thiosulfate ions are not adsorbed by the ionexchange resin and only ferricyanide ions and/or the ferrocyanide ions are adsorbed on the ion-exchange resin. Therefore, the eluate obtained on regenerating the anion-exchange resin containing the adsorbed ions contains the ferricyanide and/or ferrocyanide ions only and does not contain any thiosulfate ions.
• the eluate from the anion-exchange treatment is obtained as a solution concentrated about 100 to 500 times, the amount of waste water to be subjected to the pyrolysis is H100 to 1/500 of the volume of the original waste solution or water before the anionexchange resin treatment.
• the equipment for the pyrolysis may be small and the amount of heat required for the pyrolysis may be small, which results in reducing greatly the cost of the treatment.
• the concentration of ferricyanide ions and/or the ferrocyanide ions is l0,00020,000 p.p.m. as free cyanide ions and the concentration of ferricyanide ions and/or ferrocyanide ions in the eluate recovered from the anionexchange resin treatment is in the aforesaid most suitable range for the pyrolysis.
• the regeneration of the weakly-basic anionexchange resin is conducted usually with an alkaline solution, the eluate from the anion-exchange resin treatment has a high pH, and hence it is unnecessary to add additional alkali, if the alkalinity issufficiently high, in the case of conducting the pyrolysis, which is also an advantage of this invention.
• ferricyanide ions and/or ferrocyanide ions present together with thiosulfate ions in waste water from photographic processings or other industrial processings are adsorbed on a weakly-basic anion-exchange resin and then the eluate from the regeneration treatment of the anion-exchange resin is subjected to the pyrolysis treatment in the presence of bromide ions to decompose completely the ferricyanide ions and/or the ferrocyanide ions in it.
• Japanese Pat. application No. 22,907/1972 discloses a process of treating waste water containing ferricyanide ions and/or ferrocyanide ions with a weakly-basic anion-exchange resin in the presence of borate ions and further Japanese Pat. application No. 52,267/1972 discloses a similar process in which a weak acid and/or a weak acid salt is used in place of the borate ions.
• ferricyanide ions and/or ferrocyanide ions in a waste solution containing these ions together with thiosulfate ions can be completely decomposed by combining the above-described principal process of this invention and the aforesaid process of the prior invention.
• ferricyanide ions and ferrocyanide ions are selectively adsorbed by the weakly-basic anion-exchange resin, the thiosulfate ions are not adsorbed by the anionexchange resin, and hence no difficulties based on the reductive action of the thiosulfate in the pyrolysis are encountered.
• At least one of borate ions, a weak acid, and a weak acid salt can be added to the waste water containing the aforesaid ions for further improving the ionexchange capacity of the weakly-basic anion-exchange resin and preventing the reduction in the ion-exchange capacity of the anion-exchange resin without obstructing the effects and the features of this invention.
• the capacity or facility of the weakly-basic anionexchange resin can be increased without obstructing the complete decomposition of the ferricyanide ions and/or the ferrocyanide ions in the waste water.
• At least one of borate ions, a weak acid, and a weak acid salt is added to waste water containing ferricyanide and/or ferrocyanide ions and thiosulfate ions, the waste water is treated with a weakly-basic anion-exchange resin, and the eluate obtained in the regeneration of the anion-exchange resin is subjected to a pyrolysis treatment in the presence of bromide ions.
• the weakly-basic anion-exchange resins which can be used in the process of this invention are those composed of matrices such as sytrene-divinylbenzene copolymer, a methacrylatedivinylbenzene copolymer, a phenol-formaldehyde copolymer, etc., having at least one of primary amines, secondary amines, and tertiary amines as the ion-exchange group.
• the matrix of the anion-exchange resin can be of any kind of resin, can be prepared in any manner, can have any polymerization degree and any fine structure such as, e.g., a gel structure, a porous structure, etc., and can be processed in any manner.
• Typical commercially available weakly-basic anionexchange resins are those sold under the trade names of Diaion WA-lO, Diaion WA-l I, Diaion WA-20, Diaion WA-ZI, and Diaion WA-3O (made by Mitsubishi Chemical Industries Co., Ltd.), Amberlite IRA-45, Amberlite IRA-93, Amberlite IR-4B, and Amberlite IRP-58 (made by JAPAN Organo Co., Ltd), and Dower-44 (made by Dow Chemical Co.).
• the weakly-basic anion-exchange resins used in this invention are, however, not limited to these materials as illustrated above.
• the structures of a few anion-exchange resins of the abovedescribed commercially available materials are shown below:
• Diaion WA-301 wherein m and n are an integers.
• the particularly regenerable weakly-basic anionexchange resins of those which can be used in the process of this invention are those having tertiary amine as the ion-exchange functional group and of them a par ticularly excellent weakly-basic anion-exchange resin is Diaion WA-lO.
• those weakly-basic anion-exchange resins have the highest ion-exchange facility to ferricyanide ions and/or ferrocyanide ions per volume of the resin and can be most easily regenerated.
• the weakly-basic anion exchangc resin there are a free-base type and a salt type but the commercially available ones are generally free base type resins. Both the free base type resin and the salt type resin can be used in this invention but the free base type resin is generally used from the standpoint of availability.
• the Weakly-basic anion-exchange resin ionexchanged by ferricyanide ions and/or ferrocyanide ions is generally regenerated using an alkaine solution.
• an alkaline solution there are illustrated an aqueous solution of an alkali metal hydroxide such as sodium hydroxide, and potassium hydroxide, an aqueous solution of an alkali metal carbonate such as sodium carbonate and potassium carbonate, and an aqueous solution of ammonia.
• the resin is regenerted with an aqueous hydrochloric acid solution or an aqueous sodium chloride solution.
• the concentration of the regeneration agent or eluent is about 1 to 20% by weight, in particular 2 to 10% by weight.
• Examples of compounds containing borate ion which can be used in this invention are boric acid, metaboric acid, and water-soluble borates such as sodium borate, potassium borate, ammonium borate, and sodium metaborate.
• Boric acid and/or the borates as illustrated above can be added to the waste water containing ferricyanide ions and/or ferrocyanide ions from photographic processings or other industrial processings and in particular, in the case of photographic processings, boric acid and/or the borate can be added to a photographic processing solution such as a bleach solution, a blix solution, and a reducer.
• the amount of boric acid and/or the borate used in this invention is usually in the range of 1/10 to 10 times the total of the moles of the ferricyanide ions and the ferrocyanide ions in the waste water from photographic processings or in a photographic processing solution such as a bleach solution, a blix solution, and a reducer. In particular, it is preferred that an amount ranging from 1/5 to 10 times the total of the moles of the ferricyanide ions and/or the ferrocyanide ions be used.
• Examples of compounds including the weak acid and/or the weak acid salt which can be used in this invention are organic acids such as acetic acid, citric acid, maleic acid, fumaric acid, oxalic acid, tartaric acid, formic acid, malonic acid, phthalic acid, succinic acid, and the like; the alkali metal salts of theseorganic acids; the ammonium salts of these organic acids; inorganic weak acids such :as phosphoric acid, boric acid, sulfurous acid, and the like; the alkali metal salts of these inorganic acids, and the ammonium saltsof these inorganic acids.
• the weak acid and/or the weak acid salt as'illustrated above can be added "to the waste watercontaining ferricyanide ions and/or ferrocyanide ions and also in theease of photographic'processings,
• the processing solution suchas a reducer.
• theammonium salt is used for the treatment of the waste water .Farmersreducer
• thesame effect is obtained by using ammonium thiosulfate as the thiosulfate.
• The. amount of the weakacid and/or the weak acid salt is in the range of 1/10 to.10
• waste water containing ferricyanide ions and/or ferrocyanide ions'in any concentration can be treated but the process of this invention can be particularly advantageously applied to waste water containingferricyanide ions and/or ferrocyanide ions in aconcentration lower than 3,000 p.p.m., in particular to waste waterhaving aconcentration lower-then 1,000 ppm.
• the processof this invention is also applicable to waste water containing thiosulfateions in an amount of lower than about 150 times the total numberof moles.
• the process is preferably applied to waste water containing thiosulfate ions in an amount of. lower than 100 times the total number of moles of the ferricyanide ions and/or.
• the ferrocyanide ions therein and in particular the I process is applied more particularly to waste water containing thiosulfate ions in an amount of lower than 50 times the total number of moles of the ferricyanide ions and/or the ferrocyanide ions.
• the weakly-basic anion-exchange resin can be practiced by any method.
• the contacting iswith the weakly-basic an-. ion-exchange resin filled in a cylindrical vesselor a column to provide a layer or zone of the ion-exchange resin and then the wastewater is passed through theion-exchange resin layer or zone from the top to the bottom but as the case may be, the waste water may be passed from the bottom tothe top.
• ferricyanide ions and- /or ferrocyanide ions can be continuously. removed from the waste water.
• the ion-exchange can be continuously. removed from the waste water.
• the treatment can be conducted by adding the weakly-basic anion-exchange resin to thewaste water stored-followed by stirring, allowing "the :ion exchange resin to settle, and recovering the resin by filtration.
• an advantage in using .the ion-. exchange resin is that the treatment can be continuously conducted and hence passing the waste water continuously througha weakly-basic anionexchange resin column is preferred to the-above described batch method.
• the regeneration of the weakly-basic anionexchange resin thus ion-exchanged with the ferricyanide ionsand/or the ferrocyanide ions is conducted using.
• analkaline aqueous .solution As the alkaline aqueous solution, there are illustrated aqueous solutions of art-alkali metal hydroxide such as sodium hydroxide and potassium hydroxide-,an aqueous solution of an alkali metal carbonate such, as sodium carbonate and potassium carbonate, and an aqueous solution of ammonia.
• the concentration of the solution used for the regeneration is about 1 to-20% by weight, preferably 2 to 10% by weight.
• the contact between the alkaline aqueous solution and the weakly-basic anion-exchange resin having ions absorbed thereon can be conducted by any manner.
• the technique described above in the contact between the waste water and the anionexchange resin can be utilized in the regeneration method also.
• the ferricyanide ions and/or the ferrocyanide ions are removed fromthe weakly-basic.
• anion-exchange resin that is to say, the solution or the eluate containing the ferricyanide ions and/or the ferrocyanide ions is removed or recovered from the ionexchange system.
• the eluate contains usually the ferri-' cyanide ions and/or ferrocyanide ions in a high concentration of ordinarily 10,000 to 100,000 ppm.
• the eluate can be quite conveniently subjected to pyrolysis since it has a high alkalinity and further it contains no salts such as a thiosulfate.
• Examples of compounds. containing. bromide ions which can be used the pyrolysis in thepresent invention are alkali metal bromides such as potassium bromide and sodium bromide; alkaline earth metal bromides such-as calcium bromide, barium bromide, and magnesium bromide; and meta] bromides such as aluminum bromide and iron bromide.
• Ammonium bromide can be also used in this invention for the same purpose. Basicallyflthe water-soluble bromies other than those heavy metal bromides catalytically promoting the decomposition of the hypochlorite, suchas copper bromide and nickel bromide, can be used in this invention.
• the concentration of the bromide-ions depends-upon the concentration of the ferricyanide ions and/or the ferrocyanide ions but his better to use an aqueous solution of thebromide having a content of higher than 0.1 glliter as'bromide ions.
• a particularly preferred content of thebromide ions is over 0.5 g/liter.
• alkali metal bromides and ammonium bromide are readily available, usually they are used for the pyrolysis treatment.
• alkali metal hydroxides such as'sodium hydroxide and potassium hydroxide
• alkali metal carbonates such as sodium carbonate and potassium carbonate. That is to say, the alkali used for the regeneration of the weakly-basic anion-exchange resin having thereon the ferricyanide ions and/or ferrocyanide ions can be used for the pyrolysis in situ.
• hypochlorites which can be used in the pyrolysis are sodium hypochlorite, potassium hypochlorite, and calcium'hypochlorite. Furthermore, chlorine can alsobe usedfor the purpose.
• the addition of the alkali is conducted so that the pH of the system is above 12 and in particular better results are obtained the closer the pH is to 'a-pl-l of-'l4.
• the eluate used for the regeneration of the weakly-basic anionexchange resin inthis invention usually has a pH higher than 12 and in such a case it is unnecessary to add an alkali to the pyrolysis system, which is quite convenient.
• the process of this invention can be applied to any waste solutions containing ferricyanide and/or ferrocyanide ions and thiosulfate ions and in particular is suitable for the treatment of waste water from photographic processings.
• a solution containing a ferricyanide is used as a bleach solution and a solution containing a thiosulfate is used as fix solution. Therefore, by developing silver halide color photographic materials, waste water containing ferricyanide and/r ferrocyanide ions and thiosulfate ions is formed or discharged.
• waste water can contain acid sodium phosphate, potassium alum, and a pH adjusting agent such as sodium hydroxide, glacial acetic acid, sodium acetate, sodium phosphate, etc.
• a bleach solution containing a ferricyanide is used in combination with a fix solution containing a thiosulfate, which results in forming waste water containing ferricyanide and/or fer rocyanide ions and thiosulfate ions. Furthermore, it sometimes happens that the ferricyanide and/or ferrocyanide ions and thiosulfate ions are carried over in the washing water from the fix solution in which the ferricyanide and/or ferrocyanide ions have been carried over.
• the waste water containing such ferricyanide and/or ferrocyanide ions and thiosulfate ions is passed through a weakly-basic anion-exchange resin, the ferricyanide ions and/or the ferrocyanide ions are recovered by regenerating the anion-exchange resin as a concentrated solution of these ions without the thiosulfate ions, and then the ferricyanide ions and the ferrocyanide ions contained in the concentrated solution can be completely decomposed into innocuous materials by subjecting the solution to pyrolysis in the presence of the bromide ions.
• the ferricyanide ions and/or the ferrocyanide ions are decomposed into ferric hydroxide, ferric ox ide, nitrogen, carbon dioxide, and alkali metal carbonates.
• the ferric hydroxide and ferric oxide thus formed can be easily removed from the solution using known techniques and the amount thereof is generally quite small.
• a solution containing ferricyanide ions and/or ferrocyanide ions and not containing any thiosulfate ions can be obtained from waste water containing ferricyanide and/or ferrocyanide ions and thiosulfate ions as the concentrated solution thereof, which is quite convenient for the subsequent pyrolysis treatment.
• the process of this invention provides quite excellent economical advantages such various aspects as chemicals, equipment, and energy which are used.
• the pyrolysis is 100 percent efficient due to the presence of the bromide ions
• the ferricyanide ions and/or the ferrocyanide ions can be completely converted into innoculous materials and thus the problem of discharging precipitates containing these noxious materials encountered in the case of employing various aggregation and precipitation processes can be completely eliminated.
• the waste water containing ferricyanide ions and ferrocyanide ions can be completely treated in an economical manner by the process of this invention.
• anion-exchange resin can be used repeatedly after regeneration, which is also a step of the process of this invention, the process is quite economical.
• the process of this invention is excellent in comparison with the conventional simple pyrolysis from the standpoint that the ferricyanide ions and/or the ferrocyanide ions can be completely decomposed and also the chemicals, energy, and equipment necessary for the process of this invention can be less, which makes this process quite economical.
• EXAMPLE 1 In a plastic column having an inside diameter of 4 cm was filled 500 ml of a weakly-basic anion-exchange resin, Diaion WA-lO (trade name, made by Mitsubishi Chemical Industries Co., Ltd.), a solution prepared by diluting farmers reducer having the composition shown below by about times with water and adding 0.3 g/liter of boric acid was passed through the ionexchange resin as an example of waste water, and then the composition of the water passed through the ionexchange resin column was analyzed.
• a weakly-basic anion-exchange resin Diaion WA-lO (trade name, made by Mitsubishi Chemical Industries Co., Ltd.)
• a solution prepared by diluting farmers reducer having the composition shown below by about times with water and adding 0.3 g/liter of boric acid was passed through the ionexchange resin as an example of waste water, and then the composition of the water passed through the ionexchange resin column was analyzed.
• Solution A 37.5 g of ferricyanide was dissolved in water to make a solution of 500 ml.
• Solution B 480 g of anhydrous sodium thiosulfate was dissolved in water to make a solution of 2 liters.
• Solution A was mixed with I Solution B in a volume ratio of l 4.
• the sample waste water thus prepared had the following compositionf Ferricyanide ions and ferrocyanide ions:
• the ionexchange resin was regenerated using 1 liter ofa 4% by weight aqueous solution of sodium hydroxide and the eluate recovered in the regeneration was subjected to a pyrolysis treatment.
• the eluate had the following composition: pH: 13.9.
• Ferricyanide ions and ferrocyanide ions p.p.m. as CN-
• the eluate having the above composition was placed in five beakers in an amount of 200 ml each and after adding thereto aqueous sodium hypochlorite solution (containing 123.0 g/liter of NaOCl) in the amount as shown in Table 2, the mixture was maintained at 85C to conduct the reaction for 2 hours. Furthermore, 8- g of sodium hydroxide was added to the mixture in the beakers ofTest No. 2 and Test No.
• EXAMPLE 2 An aqueous solution containing 10.6 g/liter of potassium ferricyanide (K [Fe(CN) and 13.5 g/liter of potassium ferrocyanide (K [Fe(CN) 3H O) was prepared and it was experimentally confirmed using this aqueous solution that the presence of the bromide ions was essential for completely decomposing the ferricyanide ions and the ferrocyanide ions in the pyrolysis treatment.
• EXAMPLE 3 plate while washing the surface with water continuously to conduct the reduction and collecting the washing water containing the farmers reducer.
• Solution A 37.5 g of potassium ferricyanide was dissolved in water to make 500 ml of total volume.
• Solution B 650 ml of ammonium thiosulfate (70% solution) was dissolved in water to make 2 liters of total volume.
• Solution A was mixed with Solution B in a volume ratio of l 4.
• the concentration of the ferricyanide ions and/or the ferrocyanide ions in the farmers reducer waste water varied over the range of to about 200 p.p.m. as total cyanide but the mean concentration of these solutions was about 100 p.p.m. as total cyanide.
• the waste water was passed through the above-described ion-exchange resin column until the concentration of the ferricyanide ions and the ferrocyanide ions in the treated water became greater than 1 p.p.m. as total cyanide content.
• the anion-exchange resin was regenerated by passing through the anion-exchange resin liters of an aqueous 6% potassium hydroxide solution at a rate of 500 ml/min. Then, after washing the anionexchange resin sufficiently with water, the above-described waste water was passed through the anion-exchange resin col umn and then the anion-exchange resin was regenerated again. This ion-exchange and regeneration cycle was repeated a total of four times. The amount of the waste water passed through the ion-exchange resin column until the content of the ferricyanide ions and ferrocyanide ions in the treated waste water became greater than 1 p.p.m. as total cyanide content was 4 tons on the average in each case. The amount, the pH, and the total cyanide content in the eluate recovered in the fourth regeneration treatment were as follows.
• an aqueous solution of sodium hypochlorite (containing 123 g/liter of NaOCl) was added to 500 ml of the eluate having the above composition so that the content of the sodium hypochlorite became 0.5 g and after further adding to the solution ammonium bromide at a level of 0.5 g as bromide ions, the mixture was heated to 8085C for 2 hours to conduct the reaction. Thereafter, water was added to the mixture to make 500 ml in total volume to compensate for the evaporated water and the analysis of the total cyanide content was conducted. The analysis in each case was conducted according to the method of JIS K0l02-29.l.2 and .115 K0l02-29.2. The total cyanide content was 0.03 p.p.m.
• EXAMPLE 4 In each of the two cylinders having an inside diameter of 4.5 cm was filled 30 ml of a weakly-basic anionexchange resin, Diaion WA-ll (trade name, made by Mitsubishi Chemical Industries Co., Ltd.). Then, a solution prepared by diluting by 100 times a bleach solution having the following composition with water was passed through one of the ion-exchange resin columns at a rate of 300 ml/min.
• a weakly-basic anionexchange resin Diaion WA-ll (trade name, made by Mitsubishi Chemical Industries Co., Ltd.
• Ferricyanide lOO g Potassium bromide 30 g Water to make 1 liter A solution prepared by diluting by times a bleach solution having the above composition with water and further adding thereto 1.0 g/liter of boric acid was passed through another ion-exchange resin column at a rate of 300 ml/min.
• the amount of the treated solution until the ferricyanide ions were detected was measured for each ion-exchange resin column. Then, the ion-exchange resin column in which the ferricyanide ions were detected in the treated solution was regenerated in the same way as described in Example 1 and then a solution prepared by diluting by 100 times the bleach solution with water or a solution prepared by diluting by 100 times the bleach solution with water and adding thereto 1.0 g/liter of boric acid was passed through the regenerated ion-exchange resin column. The results obtained are shown in the following table.
• EXAMPLE 5 In each of two cylindrical columns having an inside diameter of 4.5 cm was filled 300 ml of a weakly-basic anion-exchange resin, Diaion WA-l I (trade name, made by Mitsubishi Chemical Industries, Co., Ltd.). A solution prepared by diluting by 100 times a bleach solution having the following composition with water was passed through one of the ion-exchange resin columns at a rate of 300 ml/min.
• a weakly-basic anion-exchange resin Diaion WA-l I (trade name, made by Mitsubishi Chemical Industries, Co., Ltd.).
• the anion-exchange resin which showed the ferricyanide ions in the treated solution was regenerated in the same way as described in Example 1 and then a solution prepared by diluting by 100 times the bleach solution of the solution prepared by diluting by 100 times the bleach solution and adding 2.0 g/liter of sodium dihydrogenphosphate was passed through the regenerated ion-exchange resin column.
• the results obtained are shown in the following table.
• a process of treating waste water containing ferricyanide ions and ferrocyanide ions which comprises bringing said waste water containing these ions into contact with a weakly-basic anion-exchange resin for adsorption of ferricyanide and ferrocyanide ions on said resin, removing said weakly-basic anion-exchange resin having adsorbed thereon ferricyanide and ferrocyanide ions from said waste water, immersing said .18 weaklwb asic, anion-exchange resin having said ferricyanide and ferrocyanide,..ions adsorbed. thereoninto an alkaline solu tionitb' provide .an alkaline concentrated solution of ,said, ferricyanide.
• ferricyanide and ferrocyanide ions are decomposed, wherein said bromide ions serve to accelerate the heat decomposition of ferricyanide ions and ferrocyanide ions during said heating.
• said weak acid is selected from the group consisting of an organic acid and an inorganic acid.
• said organic acid is selected from the group consisting of acetic acid, citric acid, maleic acid, fumaric acid, oxalic acid, tartaric acid, formic acid, malonic acid, phthalic acid, or succinic acid
• said inorganic acid is selected from the group consisting of phosphoric acid, boric acid, or sulfurous acid.
• said weak acid salt is a member selected from the group consisting of an alkali metal salt or an ammonium salt of a member selected from the group consisting of a weak organic acid and a weak inorganic acid.
• said weak acid salt is a member selected from the group consisting of an alkali metal salt and an ammonium salt of a member selected from the group consisting of acetic acid, citric acid, maleic acid, fumaric acid, oxalic acid, tartaric acid, formic acid, malonic acid, phthalic acid, succinic acid, phosphoric acid, boric acid, and sulfurous acid.
• said alkaline solution comprises a solution of a member selected from ions are from a compound containing bromide ions, said compound being a member selected from the group consisting of an alkali metal bromide, an alkaline earth metal bromide, a water soluble metal bromide, or

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  • 1972-10-23 JP JP47106060A patent/JPS5143312B2/ja not_active Expired
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