EP1809574A2 - Verfahren zur herstellung von natriumdithionit - Google Patents
Verfahren zur herstellung von natriumdithionitInfo
- Publication number
- EP1809574A2 EP1809574A2 EP05805323A EP05805323A EP1809574A2 EP 1809574 A2 EP1809574 A2 EP 1809574A2 EP 05805323 A EP05805323 A EP 05805323A EP 05805323 A EP05805323 A EP 05805323A EP 1809574 A2 EP1809574 A2 EP 1809574A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- sodium
- mother liquor
- formate
- substream
- sodium dithionite
- 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.)
- Withdrawn
Links
- JVBXVOWTABLYPX-UHFFFAOYSA-L sodium dithionite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])=O JVBXVOWTABLYPX-UHFFFAOYSA-L 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title abstract description 6
- 239000012452 mother liquor Substances 0.000 claims abstract description 34
- 239000004280 Sodium formate Substances 0.000 claims abstract description 23
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 claims abstract description 23
- 235000019254 sodium formate Nutrition 0.000 claims abstract description 23
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 19
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001728 nano-filtration Methods 0.000 claims abstract description 18
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 16
- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 claims abstract description 15
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000000926 separation method Methods 0.000 claims abstract description 15
- 150000003388 sodium compounds Chemical class 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 47
- 239000012528 membrane Substances 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 7
- 230000036961 partial effect Effects 0.000 claims description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- 238000001223 reverse osmosis Methods 0.000 claims description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 4
- 238000004064 recycling Methods 0.000 claims description 4
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 3
- 230000005587 bubbling Effects 0.000 claims description 3
- 235000019253 formic acid Nutrition 0.000 claims description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical compound OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 claims 2
- 150000001875 compounds Chemical class 0.000 claims 1
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 abstract description 11
- 235000010269 sulphur dioxide Nutrition 0.000 abstract description 7
- 239000002904 solvent Substances 0.000 abstract 1
- 239000004291 sulphur dioxide Substances 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 16
- 239000002351 wastewater Substances 0.000 description 15
- 239000012466 permeate Substances 0.000 description 9
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 7
- 230000014759 maintenance of location Effects 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 6
- 239000012465 retentate Substances 0.000 description 6
- 230000002829 reductive effect Effects 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 4
- 235000019345 sodium thiosulphate Nutrition 0.000 description 4
- 150000001450 anions Chemical class 0.000 description 3
- 238000000909 electrodialysis Methods 0.000 description 3
- 238000005755 formation reaction Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 238000010979 pH adjustment Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- -1 thiosulfate ions Chemical class 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 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 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229940079826 hydrogen sulfite Drugs 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 description 2
- 230000003204 osmotic effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 238000000108 ultra-filtration Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000001476 alcoholic effect Effects 0.000 description 1
- 239000003011 anion exchange membrane Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000007700 distillative separation Methods 0.000 description 1
- WBZKQQHYRPRKNJ-UHFFFAOYSA-L disulfite Chemical compound [O-]S(=O)S([O-])(=O)=O WBZKQQHYRPRKNJ-UHFFFAOYSA-L 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000012456 homogeneous solution Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005373 pervaporation Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000010626 work up procedure Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/64—Thiosulfates; Dithionites; Polythionates
- C01B17/66—Dithionites or hydrosulfites (S2O42-)
Definitions
- the present invention relates to an improved process for the preparation of sodium dithionite by the formate process, in which recycled from the wastewater sodium formate is recycled to the synthesis approach.
- DE 2 651 418 C2 relates to a process for working up the mother liquors with acids obtained in the preparation of sodium umdithionite by the sodium formate process by reacting sodium formate, sulfur dioxide and an alkaline sodium compound in an aqueous alcoholic solution after separation of the sodium dithionite.
- alcohol and methyl formate are removed by distillation from the mother liquors, the remaining mother liquor is mixed with such amounts of formic acid that the pH is 3.0 to 4.5, the mother liquor heated to temperatures of 75 to 110 0 C, the precipitated sulfur separated and isolated from the mother liquor sodium formate.
- DE 4 437 253 A1 relates to a process for preparing anhydrous sodium umdithionite by reacting sodium formate, sulfur dioxide and an alkaline sodium compound in aqueous methanolic solution in a first stage, separating the precipitated product from the mother liquor, lowering the content of sodium thiosulfate in the mother liquor and recycling the resulting solution to the first stage.
- the mother liquor is withdrawn 10 to 60 percent by weight of the water present in it and the remaining solution is cooled to a temperature between (-40) and 10 0 C and the resulting precipitate separated.
- JP 2001-270844 describes a process for obtaining sodium formate from the wastewater of a sodium dithionite synthesis by means of a two-stage electrodialysis.
- a first electrodialysis step (cation exchange membrane and for monovalent species selective anion exchange membrane)
- a solution enriched in formate and hydrogen sulfite is first obtained.
- sulphite is subsequently oxidized to sulphate.
- the pH is adjusted to be close to or greater than 7 and again the divalent sulfate is separated from the monovalent formate.
- Such a multi-stage process is very als ⁇ agile.
- the oxidative intermediate step is very time-consuming in the case of oxidation with atmospheric oxygen and makes additional use or auxiliary materials necessary.
- the object of the present invention was to provide a process for the preparation of sodium dithionite, which comprises an economic and technically feasible recirculation of sodium formate from the wastewater, it being possible to recycle the recovered sodium formate into the synthesis.
- step (b) is a filtrative separation of Natriumdithio- nit from the sodium dithionite mother liquor and in step (c) to a distillative separation of methanol from the residual mother liquor.
- Sodium compounds which are preferably used for sodium dithionite synthesis are e.g. Sodium carbonate, sodium bicarbonate or sodium hydroxide.
- the sodium thiosulfate present in the wastewater must be substantially depleted, since it represents an interfering component for the substeps (a) and (b) of the process according to the invention. This is done according to the invention by means of a nanofiltration process.
- Nanofiltration like reverse osmosis and ultrafiltration, is a pressure-driven membrane process for the separation of dissolved components from aqueous solutions. Nanofiltration has to be classified in terms of its separation behavior between reverse osmosis and ultrafiltration, whereby there are no sharp boundaries in the transition areas.
- a special feature of nanofiltration membranes is their high ion selectivity: salts with monovalent anions can pass through the membrane to a great extent, while salts with polyvalent ions are retained to a much greater extent.
- the wastewater stream in step (d) of the process is divided into two sub-streams on a suitable nanofiltration membrane.
- the thiosulfate ions preferably remain in the retentate (first portion rich in thiosulfate), since they are preferably retained by the nanofiltration membrane in relation to monovalent anions (for example the formations).
- the formations can pass the nanofiltration membrane to a large extent, so that the permeate (filtrate) thus obtained forms a second thiosulfate-poor, formate-containing partial stream.
- the membrane separation unit used in nanofiltration in the process according to the invention all membranes are suitable which are stable in the respective system under the necessary separation conditions and which have a selectivity between monovalent and polyvalent anions.
- the separating layers of the usable membranes can be made of organic polymers, ceramics, carbon or combinations thereof.
- the separating layers are usually constructed on a single or multilayer porous substructure which consists of the same or at least one different material than the separating layer.
- the membranes are usually used in pressure-resistant housings which permit the separation between retentate (thiosulfate-rich partial stream) and permeate (thiosulfate-poor partial stream) at the pressure conditions required for the separation.
- the membranes can be made into flat, tubular, multichannel element, capillary or wound geometry, for which corresponding pressure housings which permit a separation between retentate and permeate are available. Furthermore, several of these elements can be combined in a housing to form a module.
- step (e) Before a recycling of thiosulfatarmen, formate-containing second substream takes place, this is concentrated in step (e) to a lower water content, since the synthesis takes place in a methanolic, low-water solution.
- the traceable amount is determined by the residual concentration of thiosulphate which is justifiable in the recycle stream (concentrated permeate stream).
- the traceable amount of formate may optionally also be limited by the solubility limit of the salts present in the recycle stream, in particular formate and salts of sulfurous acid, if preferably a homogeneous solution is to be metered into the synthesis batch as recycled material.
- the pH of the residual mother liquor before carrying out step (d) to a pH value in deviation from the pH of the residual mother liquor obtained in step (b) or (c) discontinued.
- a whole series of other ionic species are present which make separation by nanofiltration more difficult.
- these are other divalent ions such as sulfite.
- these are other divalent ions such as sulfite.
- the retention of the total sulfite contained in the waste water of the formate process, comprising disulfite, sulfite and hydrogen sulfite can be reduced by this pH adjustment, so that this can also be partially recycled into the synthesis together with the sodium formate.
- the pH of the residual mother liquor prior to step (d) is adjusted by bubbling sulfur dioxide or by adding formic acid to the remainder of the mother liquor.
- it is also any other suitable method known in the art for pH adjustment applicable.
- the nanofiltration is carried out in step (d) with an overflow velocity between 0.05 m / s and 8 m / s, more preferably between 0.1 m / s and 4 m / s.
- an overflow velocity between 0.05 m / s and 8 m / s, more preferably between 0.1 m / s and 4 m / s.
- the nanofiltration in step (d) is carried out with a transmembrane pressure difference between 5 bar and 70 bar, preferably between 10 bar and 50 bar, more preferably between 20 bar and 30 bar.
- the transmembrane pressure difference is present between permeate and retention space. This pressure difference overcomes the osmotic pressure which builds up in nanofiltration and achieves the highest possible permeate flow with the smallest possible membrane area.
- the temperature of step (d) is supplied residual mother liquor between 20 ° C and 90 ° C, particularly preferably between 3O 0 C and 50 0 C.
- these temperatures can be cost-effective polymeric Use membranes if they are stable.
- these temperatures can be adjusted cost-effectively (river water, steam which has been reduced in tension), the boiling point of the residual mother liquor is not exceeded and sufficiently high permeate flows are achieved.
- the concentration of sodium formate in the second partial stream in step (e) is preferably carried out by a thermal process or by membrane processes, such as reverse osmosis or pervaporation.
- a known thermal process for the concentration For example, the evaporation consists of evaporating the water.
- Reverse osmosis is a known pressure-driven membrane process in which a pressure which is greater than the osmotic pressure of the liquid is applied to the water-containing liquid which is in contact with a semipermeable membrane. This forces the water through the membrane. Particles dissolved in the water (for example formations) can not pass through the membrane.
- the formate-containing solution can thus be concentrated.
- the concentration in step (e) preferably takes place up to a water content of ⁇ 30%, particularly ⁇ 15%, which is contained in the aufkonzent ⁇ ration second partial stream, based on the original amount of water.
- the recycling in step (f) is carried out in such an amount that in the synthesis batch a concentration of thiosulphate of 5000 ppm, preferably 2500 ppm, particularly preferably 100 ppm, is not exceeded. At higher thiosulphate concentrations in the recycle stream, the synthesis and the subsequent filtration of the product are disturbed.
- a polymeric nanofiltration membrane (Desal 5 DK, GE Osmonics Inc.) is contacted with a production effluent having a typical composition for a wastewater from the synthesis of sodium dithionite as present after step (c) of the process of the present invention.
- the solution contains 30 g / l of total sulfite, 12 g / l of sodium thiosulfate and 60 g / l of sodium formate and has a pH of 5.6.
- the transmembrane pressure during the nanofiltration is 10 bar, the temperature 40 ° C.
- the membrane is overflowed by the solution at an overflow velocity of 0.5 m / s.
- MK [retentate mass at the beginning] / [retentate mass at time t]) of 1.5.
- R 1 - [concentration of permeate] / [concentration of retentate]:
- Example 1 The solution of Example 1 is adjusted by bubbling sulfur dioxide to a pH of 4.0. Subsequently, the solution with the same membrane as in Example 1 at 40 0 C, an overflow velocity of 0.5 m / s and a transmembrane pressure of 20 bar in contact. The solution is concentrated with a mass concentration factor of 2.2. The following results are obtained:
- the membrane has a lower retention, so that its concentration in the permeate over Example 1 can be increased.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102004053090A DE102004053090A1 (de) | 2004-11-03 | 2004-11-03 | Verfahren zur Herstellung von Natriumdithionit |
PCT/EP2005/011786 WO2006048293A2 (de) | 2004-11-03 | 2005-11-03 | Verfahren zur herstellung von natriumdithionit |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1809574A2 true EP1809574A2 (de) | 2007-07-25 |
Family
ID=36143400
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05805323A Withdrawn EP1809574A2 (de) | 2004-11-03 | 2005-11-03 | Verfahren zur herstellung von natriumdithionit |
Country Status (5)
Country | Link |
---|---|
US (1) | US7968076B2 (de) |
EP (1) | EP1809574A2 (de) |
CN (1) | CN101056820A (de) |
DE (1) | DE102004053090A1 (de) |
WO (1) | WO2006048293A2 (de) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102005049568A1 (de) | 2005-10-17 | 2007-04-19 | Basf Ag | Verfahren zur kontinuierlichen Hydrierung oder hydrierenden Aminierung |
US8027479B2 (en) | 2006-06-02 | 2011-09-27 | Coding Technologies Ab | Binaural multi-channel decoder in the context of non-energy conserving upmix rules |
CN102050471B (zh) * | 2010-11-05 | 2012-05-23 | 烟台大学 | 甲酸钠法保险粉废液中甲酸钠和亚硫酸钠的回收方法 |
Family Cites Families (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2442418B2 (de) * | 1974-09-05 | 1980-04-17 | Basf Ag, 6700 Ludwigshafen | Verfahren zur Herstellung von Natriumdithionit |
JPS51136596A (en) | 1975-05-21 | 1976-11-26 | Mitsui Toatsu Chem Inc | Method for processing mot her liquid in the production of sodium dithionite |
GB1504087A (en) | 1975-05-21 | 1978-03-15 | Mitsui Toatsu Chemicals | Process for treating the mother liquor in the production of anhydrous sodium dithionite |
JPS51136597A (en) | 1975-05-21 | 1976-11-26 | Mitsui Toatsu Chem Inc | Method for processing mother solution of sodium dithionite anhydride production |
JPS52138090A (en) | 1976-04-26 | 1977-11-17 | Mitsui Toatsu Chem Inc | Treatment of mother liquor from production of anhydrous sodium dithionite |
DE2646825A1 (de) * | 1976-10-16 | 1978-04-20 | Basf Ag | Verfahren zur kontinuierlichen herstellung von natriumdithionitloesungen durch kathodische reduktion |
JPS5350090A (en) * | 1976-10-20 | 1978-05-08 | Mitsui Toatsu Chem Inc | Production of anhydrous sodium dithionite |
DE2651418C2 (de) | 1976-11-11 | 1986-01-09 | Basf Ag, 6700 Ludwigshafen | Verfahren zur Aufarbeitung der bei der Herstellung von Natriumdithionit nach dem Natriumformiatverfahren anfallenden Mutterlaugen |
DE2716032C2 (de) | 1977-04-09 | 1985-11-14 | Basf Ag, 6700 Ludwigshafen | Verfahren zur Herstellung von Natriumdithionit |
CA2016353A1 (en) * | 1989-05-23 | 1990-11-23 | Charles E. Winslow, Jr. | Method for re-use of aqueous co-product from manufacture of sodium dithionite |
DE4437253A1 (de) | 1993-10-28 | 1995-05-04 | Basf Ag | Verfahren zur Herstellung von wasserfreiem Natriumdithionit |
US5792441A (en) * | 1996-10-11 | 1998-08-11 | Pulp And Paper Research Institute Of Canada | Fixed-resin bed technologies for the treatment of the chlorine dioxide generator effluent and feeds stream |
FR2773891B1 (fr) | 1998-01-21 | 2000-02-18 | Eastman Kodak Co | Procede pour le traitement de bains de stabilisation saisonnes utilises dans les traitements photographiques |
DE69920067D1 (de) | 1998-01-22 | 2004-10-21 | Eastman Kodak Co | Verfahren und Vorrichtung zur Rückführung von Waschwasser in photographischen Verarbeitungen |
DE19954299A1 (de) * | 1999-11-11 | 2001-05-17 | Eilenburger Elektrolyse & Umwelttechnik Gmbh | Verfahren zur gleichzeitigen elektrochemischen Herstellung von Natriumdithionit und Natriumperoxodisulfat |
JP2001270844A (ja) | 2000-03-23 | 2001-10-02 | Mitsubishi Gas Chem Co Inc | ハイドロサルファイト製造廃液からのギ酸ナトリウムの回収方法 |
-
2004
- 2004-11-03 DE DE102004053090A patent/DE102004053090A1/de not_active Withdrawn
-
2005
- 2005-11-03 CN CNA2005800381074A patent/CN101056820A/zh active Pending
- 2005-11-03 EP EP05805323A patent/EP1809574A2/de not_active Withdrawn
- 2005-11-03 WO PCT/EP2005/011786 patent/WO2006048293A2/de active Application Filing
- 2005-11-03 US US11/666,973 patent/US7968076B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
See references of WO2006048293A3 * |
Also Published As
Publication number | Publication date |
---|---|
US20080187484A1 (en) | 2008-08-07 |
CN101056820A (zh) | 2007-10-17 |
US7968076B2 (en) | 2011-06-28 |
DE102004053090A1 (de) | 2006-05-04 |
WO2006048293A2 (de) | 2006-05-11 |
WO2006048293A3 (de) | 2007-02-15 |
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