EP1809574A2 - Procede pour produire du dithionite de sodium - Google Patents

Procede pour produire du dithionite de sodium

Info

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Withdrawn
Application number
EP05805323A
Other languages
German (de)
English (en)
Inventor
Armin Diefenbacher
Hartwig Voss
Reinhard Schneider
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Publication of EP1809574A2 publication Critical patent/EP1809574A2/fr
Withdrawn legal-status Critical Current

Links

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

L'invention concerne un procédé pour produire du dithionite de sodium, ce procédé comprenant les opérations suivantes: (a) réaliser une charge de départ de synthèse à base de formiate de sodium, de dioxyde de soufre et d'un composé de sodium alcalin dans une solution méthanolique aqueuse pour obtenir une eau-mère de dithionite de sodium, (b) séparer le dithionite de sodium de l'eau-mère de dithionite de sodium, une eau-mère résiduelle se formant, (c) séparer le méthanol de l'eau-mère résiduelle, (d) séparer par nanofiltration l'eau-mère résiduelle en un premier flux partiel riche en thiosulfate et en un deuxième flux partiel pauvre en thiosulfate mais contenant du formiate, (e) concentrer le formiate de sodium dans le deuxième flux partiel et (f) remettre le deuxième flux partiel concentré en circulation dans l'opération (a).
EP05805323A 2004-11-03 2005-11-03 Procede pour produire du dithionite de sodium Withdrawn EP1809574A2 (fr)

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 (fr) 2004-11-03 2005-11-03 Procede pour produire du dithionite de sodium

Publications (1)

Publication Number Publication Date
EP1809574A2 true EP1809574A2 (fr) 2007-07-25

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP05805323A Withdrawn EP1809574A2 (fr) 2004-11-03 2005-11-03 Procede pour produire du dithionite de sodium

Country Status (5)

Country Link
US (1) US7968076B2 (fr)
EP (1) EP1809574A2 (fr)
CN (1) CN101056820A (fr)
DE (1) DE102004053090A1 (fr)
WO (1) WO2006048293A2 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
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)

* Cited by examiner, † Cited by third party
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 (fr) * 1989-05-23 1990-11-23 Charles E. Winslow, Jr. Methode de reutilisation d'un produit secondaire aqueux provenant de la preparation de dithionite de sodium
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

Non-Patent Citations (1)

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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 (fr) 2006-05-11
WO2006048293A3 (fr) 2007-02-15

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