WO2002051754A1 - Procede pour separer un tensioactif d'un liquide - Google Patents

Procede pour separer un tensioactif d'un liquide Download PDF

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Publication number
WO2002051754A1
WO2002051754A1 PCT/NL2001/000929 NL0100929W WO02051754A1 WO 2002051754 A1 WO2002051754 A1 WO 2002051754A1 NL 0100929 W NL0100929 W NL 0100929W WO 02051754 A1 WO02051754 A1 WO 02051754A1
Authority
WO
WIPO (PCT)
Prior art keywords
liquid
surfactant
stream
centrifugal forces
crystalline particles
Prior art date
Application number
PCT/NL2001/000929
Other languages
English (en)
Inventor
Annemieke Wilhelmina Charlotte Van Den Berg
Sander Lems
Original Assignee
Technische Universiteit Delft
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 Technische Universiteit Delft filed Critical Technische Universiteit Delft
Publication of WO2002051754A1 publication Critical patent/WO2002051754A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • 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
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • 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
    • C02F2101/30—Organic compounds
    • C02F2101/301—Detergents, surfactants

Definitions

  • the present invention relates to a method of separating a surfactant from a liquid wherein the temperature of the liquid is reduced to below the Krafft temperature of the surfactant for the formation of crystalline particles of the surfactant.
  • the object of the invention to provide a method of the kind mentioned in the preamble, facilitating the effective separation the surfactant.
  • the invention is characterized in that the crystalline particles that developed due to lowering the temperature of the liquid are separated by means of centrifugal forces, yielding a surfactant-depleted liquid.
  • high concentrations of surfactants are used. For various reasons these often have to be removed again from the liquid containing them. In the past this has been attempted by means of evaporation, coagulation, adsorption, extraction with solvents and ultrafiltration. All these techniques have one or more drawbacks making their application practically and economically unattractive.
  • the method according to the invention effectively uses the development of crystallisa- tion at reduced temperatures, wherein micelles dissolve in favour of the formation of crystalline surfactants. In contrast to micelles, crystals can be separated under the influence of relatively low centrifugal forces. In prac- tice the surfactant will be an ionogenic surfactant.
  • the method according to the invention may be applied for
  • the liquid is maintained for at least 5 minutes, and more preferably for at least 10 minutes at that temperature. For many applications this suffices to largely cause the micelles to dissolve.
  • the method is further suitable for continuous execution and is preferably applied in this manner.
  • the liquid is fed into a crystallisation tank containing an excess of a liquid cooled to below the Krafft temperature, with which the liquid being continuously added is mixed.
  • the liquid is contacted with the crystalline material serving as seeding material.
  • This ap- proach helps to ensure that no problems arise resulting from the precipitation of solid surfactant during the cooling of the liquid.
  • the liquid is preferably supplied continuously.
  • the crystalline surfactant separated by centrifu- gal forces is preferably returned to liquid comprising surfactants that have been cooled down to below the Krafft temperature in a crystallisation tank to serve as seeding crystals for the formation of easily separable crystalline surfactant. This is a more convenient and operationally safer method of effectively separating surfactants.
  • Separation by centrifugal forces preferably comprises two steps, wherein in a first step, under the in- fluence of relatively minor centrifugal forces a first stream comprising large crystalline particles and a second stream comprising small crystalline particles is generated, the second stream comprising small crystalline par- tides being used as seeding material, and in a second step the first stream comprising large crystalline particles is separated under relatively great centrifugal forces into a third stream comprising crystalline particles and a substantially surfactant-free fourth stream.
  • a stream of small particles that may be used as seeding crystals for the crystallisation is generated by this approach, while on the other hand another chance is provided for removing small particles that have come into the second step after all. It is preferred for a ripening tank to be provided after the crystallisation tank, to which liquid from the crystallisation tank is fed.
  • concentration of surfactant present in micelles may diminish further and growth of crystals may occur, also at the expense of small crystals.
  • a crystalline surfactant-comprising liquid is preferably discharged from the ripening tank and subjected to centrifugal forces.
  • centrifugal forces it is in particular the large, easily separable crystals that are subjected to the centrifugal forces. Consequently the centrifugal forces do not have to be very great.
  • the surfactant-comprising liquid contains dirt particles, which are not supposed to enter the surfactant, the surfactant liquid may be subjected to centrifugal forces prior to cooling.
  • An important application of the method according to the invention is the one where the waste water stream from an industrial laundry is used as the surfactant- comprising liquid.
  • the method according to the invention not only makes it possible in an economically attractive manner to comply with the ever evolving environmental demands, but the invention also makes reuse of the surfactant possible.
  • the great efficiency of the method in addition, makes it possible to launder with higher soap concentrations, thereby increasing the speed of the laundry process. In this way the capacity of an existing laundry is increased. If frothing is no problem, the liquid may be cooled and mixed by means of blowing a cold gas through it.
  • the drawing shows an apparatus suitable for separating a surfactant such as sodium myristate (Krafft temperature 32°C, critical micelle concentration (CMC) 0.07g/l).
  • a liquid A comprising surfactant is fed to a crystallisation tank for 1.
  • the crystallisation tank 1 is stirred by means of a stirring device 2 and cooled by means of a cooling device, in the present case a heat exchanger 3.
  • the crystallisation tank 1 is maintained at a temperature below the Krafft temperature, for example five degrees below.
  • liquid comprising crystalline surfactant is fed to the ripening tank 5, which is also stirred with an agitator 6. At the expense of the surfactant concentration present in the form of micelles and also at the expense of small crystals crystalline growth occurs in the ripening tank 5.
  • liquid comprising crystalline surfactant is fed to a first hydrocy- clone 8 where two streams are formed. Under the influence of centrifugal forces in the hydrocyclone 8 large crystal- line particles enter a first stream that via a pipe 9 is conducted to a second hydrocyclone 10. From the first hydrocyclone 8 a second stream of small crystalline particles is fed via a pipe 11 to the crystallisation tank 1 to serve there as seeding crystals.
  • the stream conducted via pipe 9 to the second hydrocyclone 10 is separated under relatively great centrifugal forces compared with the centrifugal forces occurring in the first hydrocyclone 8 into the surfactant- comprising third stream B, which is discharged via p ' ipe 12.
  • the surfactant present in the third stream B may optionally be returned to an industrial washing process, or processed further, for example, evaporated.
  • From the hydrocyclone 10 comes a stream C that is to a large extent free from surfactant, which is discharged via pipe 13.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Physical Water Treatments (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

La présente invention concerne un procédé pour séparer un tensioactif d'un liquide, tel qu'un effluent d'eaux usées provenant d'une blanchisserie industrielle. Selon la présente invention, ce liquide est refroidi à une valeur inférieure à la température de Krafft du tensioactif et soumis à des forces centrifuges pour la séparation de particules cristallines formées. Cette séparation est de préférence effectuée à l'aide d'un hydrocyclone.
PCT/NL2001/000929 2000-12-22 2001-12-20 Procede pour separer un tensioactif d'un liquide WO2002051754A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1016971A NL1016971C2 (nl) 2000-12-22 2000-12-22 Werkwijze voor het afscheiden van een oppervlakteactieve stof uit een vloeistof.
NL1016971 2000-12-22

Publications (1)

Publication Number Publication Date
WO2002051754A1 true WO2002051754A1 (fr) 2002-07-04

Family

ID=19772640

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL2001/000929 WO2002051754A1 (fr) 2000-12-22 2001-12-20 Procede pour separer un tensioactif d'un liquide

Country Status (2)

Country Link
NL (1) NL1016971C2 (fr)
WO (1) WO2002051754A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259568A (en) * 1963-03-21 1966-07-05 Gen Mills Inc Treatment of aqueous waste solutions
US4235712A (en) * 1979-04-05 1980-11-25 Conoco, Inc. Removal of anionic surfactants from water
EP0250394A2 (fr) * 1986-06-18 1987-12-23 Franz Barth Procédé et dispositif pour la purification d'eau résiduaire provenant des imprimeries, en particulier des installations de sérigraphie
WO1994024245A1 (fr) * 1993-04-08 1994-10-27 The Procter & Gamble Company Purification de tensioacitfs constitues de sulfates d'alkyle (2, 3) secondaires

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259568A (en) * 1963-03-21 1966-07-05 Gen Mills Inc Treatment of aqueous waste solutions
US4235712A (en) * 1979-04-05 1980-11-25 Conoco, Inc. Removal of anionic surfactants from water
EP0250394A2 (fr) * 1986-06-18 1987-12-23 Franz Barth Procédé et dispositif pour la purification d'eau résiduaire provenant des imprimeries, en particulier des installations de sérigraphie
WO1994024245A1 (fr) * 1993-04-08 1994-10-27 The Procter & Gamble Company Purification de tensioacitfs constitues de sulfates d'alkyle (2, 3) secondaires

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SCHRODER F R ET AL: "Effect of waste water treatment technology on the elimination of anionic surfactants", WASTE MANAGEMENT, ELSEVIER, NEW YORK, NY, US, vol. 19, no. 2, April 1999 (1999-04-01), pages 125 - 131, XP004163911, ISSN: 0956-053X *

Also Published As

Publication number Publication date
NL1016971C2 (nl) 2002-06-25

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