WO2013041448A1 - Élimination de composés organiques de faible poids moléculaire présents dans des solutions d'halogénures inorganiques - Google Patents

Élimination de composés organiques de faible poids moléculaire présents dans des solutions d'halogénures inorganiques Download PDF

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Publication number
WO2013041448A1
WO2013041448A1 PCT/EP2012/068016 EP2012068016W WO2013041448A1 WO 2013041448 A1 WO2013041448 A1 WO 2013041448A1 EP 2012068016 W EP2012068016 W EP 2012068016W WO 2013041448 A1 WO2013041448 A1 WO 2013041448A1
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WIPO (PCT)
Prior art keywords
accordance
acid
molecular weight
ppm
content
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PCT/EP2012/068016
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English (en)
Inventor
Luca SAONER
Joao MARQUES
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Solvay Sa
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Publication of WO2013041448A1 publication Critical patent/WO2013041448A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027—Nanofiltration
    • 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
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration

Definitions

  • the instant invention relates to the use of certain membranes to reduce the content of low molecular weight organic compounds from inorganic halide solutions having a high halide content.
  • Inorganic halide solutions are useful for the manufacture of hydroxide solutions and elementary halogen by electrochemical processes, in particular by electrolysis.
  • the most widely used commercial process of this type is the so called chlor-alkali electrolysis in which chlorine and caustic soda are prepared via the electrolysis of sodium chloride solutions (often also referred to as brine).
  • brine sodium chloride solutions
  • the most economic process makes use of ion- exchange membranes which transport cations from the anodic side to the cathodic side and thus chlorine is obtained in the anodic chamber and sodium hydroxide in the cationic chamber.
  • brine has to be recycled and quite frequently such brine contains organic compounds as contaminants. Such contamination negatively affects the energy consumption of the electrolysis process as well as the lifetime of the membrane and thus it is desirable to remove these components prior to recycling the brine to the electrolysis process.
  • Nanofiltration is a membrane based pressure driven separation process.
  • the driving force of the separation process is the pressure difference between the feed and the filtrate.
  • nanofiltration membranes have so-called molecular weight cut-off (MWCO) values of approximately 200 to 1000 Dalton. Compounds having a molecular weight exceeding the molecular weight cut-off are retained on the feed side of the membrane whereas lower molecular weight compounds permeate through the membrane.
  • MWCO molecular weight cut-off
  • the halide concentration of salt solutions used in electrolysis must be significantly higher (by orders of magnitude) than the salt concentrations tested in Choi et al. because otherwise the process could not be operated in an economically feasible manner. Taking into account the results of Choi, one would have assumed that the rejection of low molecular weight compounds in solutions with a high halide content would decrease significantly, [0010]
  • the salt rejection of the available nanofiltration membranes typically is in the range of from 10 to 100 %, bivalent salts being rejected basically quantitatively and monovalent salts being usually rejected in an amount of from 10 to 80 %. This degree of rejection would be inacceptable in halide solutions used in electrolysis as the lower halide content of the purified solution would directly negatively impact the costs of the process.
  • the broadest field of application for nanofiltration membranes is actually the preparation of potable water from salt water, i.e. the rejection of salts.
  • This object is achieved in accordance with the instant invention by the use of nanofiltration membranes to reduce the content of low molecular weight organic compounds, having a molecular weight of at most 200 Daltons , in solutions containing at least 500 ppm of an inorganic halide, wherein the solutions exhibit a pH value higher than or equal to 2.
  • the content of the inorganic halide and the pH of the solutions are to be understood as the content and the pH of the solutions before submission to nanofiltration.
  • This object is therefore achieved in accordance with the instant invention by the use of nanofiltration membranes to reduce the content of at least one low molecular weight organic compound, having a molecular weight of at most 200 Daltons , in solutions containing at least 500 ppm of an inorganic halide, wherein the solutions exhibit a pH value higher than or equal to 2.
  • the low molecular weight organic compounds have a molecular weight preferably of at most 150 Dalton, more preferably of at most 100 Dalton, yet more preferably of at most 80 Dalton and still more preferably of at most 70 Dalton. Low molecular weight organic compounds having a molecular weight of at most 50 Dalton are also convenient.
  • Nanofiltration is commonly allocated between the separation limits of reversed osmosis and ultrafiltration. The pressure applied is generally within the range of from 0.2 to 5 MPa, in particular in the range of from 0.3 to 4 MPa, and more specifically in the range of from 0.3 to 1.1 MPa.
  • nanofiltration membranes comprise a support structure and a selective layer which may be a composite of several layers in itself.
  • the selectivity of a nanofiltration membrane is governed by essentially two parameters - the molecular weight and the electric charge of the compounds.
  • the permeability is higher for monovalent ions in diluted solution, bivalent ions being normally rejected to a very high degree.
  • Nanofiltration membranes are known to the skilled person and
  • any nanofiltration membrane may be used in accordance with the instant invention, there is no specific limitation as to composition or structure of the membrane.
  • Dow Chemical through its subsidiary Filmtec and Koch Membrane systems are two suppliers offering a broader range of nanofiltration membranes.
  • Other suppliers are Toray, Fluid systems or Nitto Denko Corporation and reference is made to the respective product leaflets of these suppliers.
  • membranes as described in EP 355 188 may be preferably used and reference is made to this patent for further details.
  • membranes are EP 1 080 777 and EP 2 269 717, the latter describing cross linked membranes on the basis of cellulose.
  • NF 270 membranes have a structure comprising a semi- aromatic piperazin based polyamide layer on top of a polysulfone microporous support reinforced with a polyester non-woven backing layer.
  • the barrier layer of the nanofiltration membranes of Filmtec ® nanofiltration membranes is shown below. Basically it is an aromatic/aliphatic polyamide with amine and carboxylate end groups: [0023]
  • preferably less than 500 and most preferably in the range of from 150 to 350 are can preferably be used in accordance with the instant invention.
  • the nanofiltration membranes are used in accordance with the instant invention to reduce the content of low molecular weight organic compounds, in particular compounds having a molecular weight of 200 Daltons , particularly preferred of less than 100 Daltons, in solutions containing at least 500 ppm of inorganic halide and exhibiting a pH value higher than or equal to 2.
  • organic acids, alcohols, aldehydes and other organic impurities commonly present in inorganic halide solutions, in particular halide solutions used in electrolysis processes may be mentioned organic acids, alcohols, aldehydes and other organic impurities commonly present in inorganic halide solutions, in particular halide solutions used in electrolysis processes.
  • the acid is more preferably an aliphatic acid.
  • the monocarboxylic acid is preferably a fatty acid, more preferably selected from the group consisting of hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, and any mixture thereof.
  • the monocarboxylic acid is also preferably selected from the group consisting of formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, and any mixture thereof, and is more preferably acetic acid.
  • the polycarboxylic acid is preferably selected from the group consisting of a dicarboxylic acid, a tricarboxylic acid, and any mixture thereof.
  • the polycarboxylic acid is more preferably a dicarboxylic acid, yet more preferably selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and any mixture thereof, still more preferably from the group consisting of oxalic acid, adipic acid, and any mixture thereof and yet more preferably oxalic acid.
  • the aliphatic acid can also be a halo carboxylic acid, preferably selected from the group consisting of monochloroacetic acid, dichloroacetic acid, trichloroacetic acid and any mixture thereof.
  • the aliphatic acid can also be an hydroxyl carboxylic acid preferably
  • glycolic acid selected from the group consisting of glycolic acid, lactic acid,
  • the alcohol is preferably selected from the group consisting of methanol, ethanol, propanol, butanol, glycerol, and any mixture thereof.
  • the aldehyde is preferably selected from the group consisting of
  • the organic compound is preferably an acid as described above.
  • low molecular weight organic acids such as formic acid, acetic acid, propionic acid, succinic acid or citric acid may be mentioned here, in particular acetic acid is frequently present in sodium chloride solutions used in chlor-alkali electrolysis, more specifically sodium chloride solutions recovered from the synthesis of chlorinated organics [which may be recycled in chlor-alkali electrolysis.
  • the organic compound is preferably an acid as described above, and more preferably acetic acid
  • the use in accordance with the instant inventions is particularly preferably applied to sodium chloride solutions used for the production of caustic soda and chlorine via electrolysis.
  • the solutions preferably exhibit a pH value higher than or equal to 3, more preferably higher than or equal to 4, yet more preferably higher than or equal to 5, still more preferably higher than or equal to 7, and most preferably higher than or equal to 9.
  • the organic acid is a mono carboxylic acid
  • the solutions exhibit a pH value higher than or equal to the pKa value of the mono carboxylic acid.
  • the organic acid is a poly carboxylic acid
  • the solutions exhibit a pH value higher than or equal to the lowest pKa value of the poly carboxylic acid, and more advantageous that the solutions exhibit a pH value higher than or equal to the highest pKa value of the poly carboxylic acid.
  • the concentration of the low molecular weight compounds in the inorganic halide solutions can vary over a wide range. Typically the content by weight is at least 10, at least 20, at least 50 or at least 100 ppm and typically at most 10 000, at most 5000, at most 500 and at most 200 ppm. These concentrations are understood to be the concentrations in the solutions before submission to nanofiltration.
  • the inorganic halide are usually selected from alkali metal halides or
  • alkaline earth metal halides in particular selected from e.g. LiHal, NaHal, KHal, CsHal, Mg(Hal)2 and Ca(Hal)2 with Hal being selected from Fluorine, Chlorine, Bromine or Iodine. Chlorides are the preferred halides.
  • brine solutions i.e. aqueous sodium chloride solutions having a sodium chloride concentration of at least 500 ppm.
  • the halide content of the inorganic halide solution can vary over a wide range and may be at least 1000 ppm, at least 2000 ppm, at least 5000 ppm or at least 10 000 ppm.
  • the upper concentration is in principle only limited by the solubility of the respective halide in water and can be preferably at most 300 000 ppm, at most 200 000 ppm, at most 100 000 ppm, at most 50 000 ppm or at most 25 000 ppm.
  • a halide content of at least 200 000 ppm is also convenient.
  • the pressure applied in the use in accordance with the instant invention is typically at least 150 000 kPa, at least 300 000 kPa or at least 1 MPa.
  • the upper limit is determined by the mechanical stability of the membrane and may be typically at most 5 MPa, at most 4 MPa, at most 2.5 MPa or at most 1.5 MPa.
  • the temperature again is basically only limited by the mechanical stability of the membrane; usually temperatures in the range of from 15 to 80 °C, in particular in the range of from 20 to 60 °C may be used, room temperature being particularly preferred as it eliminates the need for providing thermal energy to the system.
  • the content of the low molecular weight organic compounds can be reduced by at least 40, preferably at least 50 and particularly preferably at least 60 %.
  • the content of inorganic halide in the permeate is at least 70, preferably at least 80 and particularly at least 90 % of the content of the starting solution fed to the purification.
  • nanofiltration membranes are commonly and most often used to desalinate salt water it was completely unexpected and surprising that same could also be used to purify inorganic halide solutions having a high halide content without a detrimental influence on the halide content.
  • Another aspect of the invention relates to a process for reducing the
  • the low molecular weight compounds have a molecular weight of at most 100 Dalton and the content of said low molecular weight compounds having a molecular weight of at most 100 Dalton is reduced.
  • a halide solution with a halide content of at least 1000 ppm is used.
  • the content of aldehydes, acids or alcohols, in particular acids and especially particular acetic acid is reduced.
  • a still other preferred embodiment of the process in accordance with the instant invention uses sodium chloride solutions.
  • the permeate contained acetic acid in an amount of from 26 to 49 ppm whereas the sodium chloride content remained at 15 000 ppm.
  • Example 2 [0059] Example 1 was repeated but with a solution containing 25 000 ppm of sodium chloride. For working pressures exceeding 1 ,1 MPa, the acetic acid concentration in the permeate was stable at 31 ppm, i.e. nearly 70 % of the acetic acid was removed. No decrease in halide concentration was detected in the permeate.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

La présente invention concerne l'utilisation de membranes de nanofiltration pour réduire la teneur en composés organiques de faible poids moléculaire ayant un poids moléculaire de 200 daltons maximum dans des solutions contenant au moins 500 mg/l d'un halogénure inorganique, les solutions présentant une valeur de pH supérieure ou égale à 2.
PCT/EP2012/068016 2011-09-19 2012-09-13 Élimination de composés organiques de faible poids moléculaire présents dans des solutions d'halogénures inorganiques WO2013041448A1 (fr)

Applications Claiming Priority (2)

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EP11181852 2011-09-19
EP11181852.2 2011-09-19

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WO2013041448A1 true WO2013041448A1 (fr) 2013-03-28

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0355188A1 (fr) 1986-04-28 1990-02-28 Filmtec Corporation Procédé de fabrication et d'utilisation de membranes en polyamide pour l'adoucissement de l'eau
US5028336A (en) * 1989-03-03 1991-07-02 Texaco Inc. Separation of water-soluble organic electrolytes
US5445741A (en) 1992-12-30 1995-08-29 Solvay Deutschland Gmbh Process for treating waste water
EP1080777A1 (fr) 1999-08-31 2001-03-07 Nitto Denko Corporation Membrane d'ultrafiltration et méthode pour sa préparation et composition d'agent utilisée pour la dernière
EP1118185A2 (fr) 1998-10-07 2001-07-25 Siemens Aktiengesellschaft Systeme de communication destine a un mode de fonctionnement
US20050029194A1 (en) * 2003-08-07 2005-02-10 Hall David Bruce Method for removal of guanidine compound from aqueous media
EP1889653A1 (fr) * 2006-08-11 2008-02-20 Millipore Corporation Membranes à nanofiltration cellulosique réticulée
US20080169202A1 (en) * 2005-02-18 2008-07-17 Akzo Nobel N.V. Process To Prepare Chlorine-Containing Compounds

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0355188A1 (fr) 1986-04-28 1990-02-28 Filmtec Corporation Procédé de fabrication et d'utilisation de membranes en polyamide pour l'adoucissement de l'eau
US5028336A (en) * 1989-03-03 1991-07-02 Texaco Inc. Separation of water-soluble organic electrolytes
US5445741A (en) 1992-12-30 1995-08-29 Solvay Deutschland Gmbh Process for treating waste water
EP1118185A2 (fr) 1998-10-07 2001-07-25 Siemens Aktiengesellschaft Systeme de communication destine a un mode de fonctionnement
EP1080777A1 (fr) 1999-08-31 2001-03-07 Nitto Denko Corporation Membrane d'ultrafiltration et méthode pour sa préparation et composition d'agent utilisée pour la dernière
US20050029194A1 (en) * 2003-08-07 2005-02-10 Hall David Bruce Method for removal of guanidine compound from aqueous media
US20080169202A1 (en) * 2005-02-18 2008-07-17 Akzo Nobel N.V. Process To Prepare Chlorine-Containing Compounds
EP1889653A1 (fr) * 2006-08-11 2008-02-20 Millipore Corporation Membranes à nanofiltration cellulosique réticulée
EP2269717A1 (fr) 2006-08-11 2011-01-05 Millipore Corporation Membranes à nanofiltration cellulosique réticulée

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
CHOI ET AL., SEPARATION AND PURIFICATION TECHNOLOGY, vol. 59, 2008, pages 17 - 25
CHOI ET AL: "A study on the removal of organic acids from wastewaters using nanofiltration membranes", SEPARATION AND PURIFICATION TECHNOLOGY, ELSEVIER SCIENCE, AMSTERDAM, NL, vol. 59, no. 1, 24 December 2007 (2007-12-24), pages 17 - 25, XP022401255, ISSN: 1383-5866, DOI: 10.1016/J.SEPPUR.2007.05.021 *

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