WO1999007748A1 - Procedes de purification de polymeres - Google Patents

Procedes de purification de polymeres Download PDF

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Publication number
WO1999007748A1
WO1999007748A1 PCT/GB1998/002362 GB9802362W WO9907748A1 WO 1999007748 A1 WO1999007748 A1 WO 1999007748A1 GB 9802362 W GB9802362 W GB 9802362W WO 9907748 A1 WO9907748 A1 WO 9907748A1
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WO
WIPO (PCT)
Prior art keywords
acrylamide
meth
enzyme
acrylamidase
poly
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Ceased
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PCT/GB1998/002362
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English (en)
Inventor
Jonathan Hughes
Yvonne Christine Armitage
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Ciba Specialty Chemicals Water Treatments Ltd
Original Assignee
Allied Colloids Ltd
Ciba Specialty Chemicals Water Treatments Ltd
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Application filed by Allied Colloids Ltd, Ciba Specialty Chemicals Water Treatments Ltd filed Critical Allied Colloids Ltd
Priority to AU86398/98A priority Critical patent/AU8639898A/en
Publication of WO1999007748A1 publication Critical patent/WO1999007748A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F6/00—Post-polymerisation treatments
    • C08F6/006—Removal of residual monomers by chemical reaction, e.g. scavenging

Definitions

  • This invention relates to processes for reducing the residual acrylamide content of polyacrylamides which have been produced at low pH, especially cationic and non-ionic polyacrylamides.
  • acrylamide homopolymers and copolymers or terpolymers of acrylamide with one or more ionic (eg cationic) or other non-ionic monomers are commonly known as polyacrylamide ⁇ .
  • Copolymers or terpolymers of acrylamide with one or more cationic monomers are termed cationic polyacrylamides.
  • Homopolymer ⁇ of acrylamide and copolymer ⁇ or terpolymer ⁇ of acrylamide with one or more other non-ionic monomers are termed nonionic polyacrylamide ⁇ .
  • Such polymers often contain residual unreacted acrylamide monomer (free acrylamide).
  • Cationic polyacrylamides are often produced at an acid pH, often around pH 4.
  • Non-ionic polyacrylamides are also often produced at acid pH, eg around pH 3.5.
  • a major reason for this is that the effectiveness of the initiator systems used for polymerisation i ⁇ optimum at this pH.
  • a commonly used buffer acid is adipic acid which has the further advantage of ⁇ tabili ⁇ ing cationic monomers again ⁇ t hydroly ⁇ is in hard water, to which they may be added on use.
  • cationic and non-ionic polyacrylamides are often at an acidic pH of around 3 to 4 and cationic polyacrylamides may contain appreciable levels of adipic acid.
  • acrylamidase enzymes have an optimum activity at a pH around neutral and that activity is significantly reduced as the pH i ⁇ lowered.
  • acrylamida ⁇ e enzymes do not function well at acidic pH.
  • Polyacrylamides which are produced at neutral pH can therefore normally be treated with acrylamidase after production, without any need to adjust the pH of the polyacrylamide.
  • US 4,786,679 and US 4,742,114 describe conventional treatments of un ⁇ pecified "polymer latex" and "polyacrylamide latex” at pH of 7 and 8.35.
  • the treatment described gives a reduction in free acrylamide to 1.4 ppm, but this requires a treatment time of 45 minutes.
  • EP-A-272,025 describes similar systems. It also demonstrates in one example the comparison of treatment of a cationic latex at pH 4 and at pH 6 , after adjustment. The re ⁇ ult ⁇ ⁇ how that although at pH 6 re ⁇ idual acrylamide levels were reduced, in that example treatment with amidase at pH 4 wa ⁇ ineffective and free acrylamide level ⁇ were not reduced.
  • EP-A-393,916 confirms the general understanding that cationic polyacrylamides should be treated with amidase by fir ⁇ t raising the pH and then treating the polymer with the acrylamidase.
  • Another system de ⁇ cribed in US 4,687,807, also demonstrates treatment of cationic emulsion polymers after pH adjustment.
  • a cationic polyacrylamide i ⁇ treated after pH adju ⁇ tment to pH 5.5.
  • pH is adjusted to 3.8.
  • Activity appears to be significantly wor ⁇ e than at pH 5.5.
  • Example 10 describes a polymer which contains a small amount of cationic monomer, although it contains a much larger amount (40%) of anionic monomer and would not be cla ⁇ ed a ⁇ a cationic polyacrylamide.
  • Example ⁇ are given of treatment of a "polyacrylamide latex" without pH adjustment. The original pH is not specified and treatment times are very long (at lea ⁇ t 10 hour ⁇ ) .
  • the ⁇ e proce ⁇ es are time consuming and rather inconvenient, in particular becau ⁇ e of the nece ⁇ ity for pH adjustment.
  • a process for producing cationic or sub ⁇ tantially non-ionic polyacrylamide having reduced level ⁇ of acrylamide monomer compri ⁇ ing providing the polyacrylamide at a pH of from 2.5 to 5.0 and contaminated with acrylamide monomer at a level of at least about 200 ppm and contacting the polyacrylamide with an acrylamidase enzyme without substantial pH adjustment and allowing the acrylamida ⁇ e enzyme to reduce the level of re ⁇ idual acrylamide monomer to 100 ppm or below.
  • Cationic polyacrylamides are often produced at a pH around 4.0.
  • Non-ionic polyacrylamide ⁇ are often produced at a pH around 3.5.
  • the correct pH i ⁇ normally obtained by including in the polymerisation mixture an appropriate buffer. Suitable buffers include acetic acid, citric acid, glutaric acid, succinic acid and, in particular, adipic acid. Mixture ⁇ of any of the ⁇ e can be used.
  • the polymer is a polyacrylamide which i ⁇ cationic or substantially non-ionic. It can be a cationic polyacrylamide, ie a polymer of acrylamide with other monomers which include cationic monomer.
  • the amount of cationic monomer is often from 3 to 90% by weight of total monomer, for instance from 20 to 70% by weight, and preferably below 50%.
  • any of the conventional cationic monomers may be used such a ⁇ diallyl ammonium monomers for instance DADMAC (diallyl dimethyl ammonium chloride) or cationic esters, for instance diallyl a ino alkyl (meth) acrylates such as DMAEA (dimethyl aminoethyl acrylate) or DMAEMA (dimethylaminoethyl methacrylate) often as acid addition or quaternary ammonium ⁇ alts or cationic amides such as DMAPMA.
  • DADMAC diallyl dimethyl ammonium chloride
  • cationic esters for instance diallyl a ino alkyl (meth) acrylates such as DMAEA (dimethyl aminoethyl acrylate) or DMAEMA (dimethylaminoethyl methacrylate) often as acid addition or quaternary ammonium ⁇ alts or cationic amides such as DMAPMA.
  • Non-ionic monomer ⁇ other than acrylamide may be included, ⁇ uch a ⁇ methacrylamide.
  • the polymer may be made amphoteric by the inclu ⁇ ion of a minor amount of anionic monomer, which is always less than the amount by weight of cationic monomer, and is preferably not more than 10 or 5% by weight of total monomer.
  • suitable anionic monomers include any of the typical anionic monomer ⁇ ⁇ uch a ⁇ ethylenically unsaturated carboxylic or sulphonic monomer ⁇ , e ⁇ pecially acrylic acid (including water- ⁇ oluble ⁇ alt ⁇ thereof).
  • the polymer can be a " non-ionic polyacrylamide, ie a homopolymer of acrylamide or a copolymer with other monomers which are also non-ionic.
  • Other non-ionic monomers include methacrylamide.
  • the polymer is substantially non-ionic but may contain minor amounts, eg below 3 wt.% and in particular below 2 or 1 wt.%, ionic monomer. For instance, a small proportion of hydrolysed acrylamide (acrylate or acrylic acid) monomer may be included although the polymer is nevertheless substantially non-ionic.
  • the polyacrylamide can be made by any suitable process. It can be made by reverse phase su ⁇ pension polymerisation and subsequent dehydration so as to produce a disper ⁇ ion of substantially dry polyacrylamide in an oil pha ⁇ e. It may be made by emulsion polymerisation so a ⁇ to produce an emul ⁇ ion of aqueou ⁇ polyacrylamide in oil.
  • the acrylamida ⁇ e enzyme may be added to the dry dispersion or wet emul ⁇ ion. It may be made in the form of a solution polymer, but preferably it i ⁇ provided in the form of particle ⁇ . Particularly preferred method ⁇ of production are those which produce a gel polymer. These include bulk gel polymerisation and bead polymerisation.
  • any treatment to which it is subjected prior to acrylamide treatment does not result in a pH change of more than one pH unit and preferably does not result in a change of more than 0.5 pH unit.
  • Other treatments may be applied which are conventionally used for other purposes. These may have a minor effect on the pH of the polyacrylamide, but they do not have any substantial effect on the pH.
  • the polyacrylamide is preferably contacted with the acrylamidase enzyme for a period of one hour or le ⁇ , more preferably 30 minute ⁇ or less, particularly 15 minutes or ' les ⁇ , before being transferred to further treatment stages if nece ⁇ ary.
  • the reduction of residual acrylamide levels to below lOOpp takes one hour or les ⁇ , preferably 30 minutes or less, more preferably 15 minutes or less.
  • the initial acrylamide level is at least 200 ppm and can be at lea ⁇ t 500 ppm or at lea ⁇ t 1,000 ppm or even up to 2,000 ppm or above. It is reduced to below 100 ppm, preferably below 30 or 50 ppm, more preferably below 20 ppm. It can be below 10 ppm or even below 5 ppm, or at undetectable levels.
  • the acrylamide content is reduced to not more than 50% of its initial level, preferably not more than 20% or 10% of its initial level and may even be below 5% or 1% of its initial level.
  • the process of the invention may be a proces ⁇ a ⁇ described in our International Publication W097/29136.
  • aqueou ⁇ polyacrylamide gel particles are provided which are contaminated with acrylamide monomer at a level of at least 200ppm and acrylamidase enzyme is applied to the aqueous gel particle ⁇ whil ⁇ t they are at a temperature of from 50 to 95°C, and the particle ⁇ are substantially immediately passed through a drying stage and subjected in that stage to a temperature of at lea ⁇ t 45°C, preferably at lea ⁇ t 50 or 60 °C, ⁇ o as to produce substantially dry particles of polyacrylamide having a level of residual acrylamide monomer of not more than lOOppm.
  • the aqueous polyacrylamide gel particle ⁇ are provided at a pH of from 2.5 to 5.0 and are treated without ⁇ ub ⁇ tantial pH adjustment before contact with the acrylamidase enzyme.
  • an acrylamidase enzyme having a Km for acrylamide not more than 10 mM is used.
  • aqueous polyacrylamide gel particles are provided which are contaminated with acrylamide monomer at a level of at least 200ppm.
  • the acrylamidase enzyme i ⁇ applied to the aqueous gel particles whil ⁇ t they are at a temperature of 50 to 95 °C and the aqueous gel particles are then held in a holding stage at a temperature of from 20 to 70°C for not more than 30 minutes.
  • the particles are then pa ⁇ ed to a drying stage and subjected in that stage to a temperature of at lea ⁇ t 45°C, preferably at least 50 or 60°C, to produce substantially dry particles.
  • thi ⁇ proce ⁇ also the polyacrylamide i ⁇ provided at a pH of from 2.5 to 5.0 and i ⁇ not subjected to any ⁇ ub ⁇ tantial pH adju ⁇ tment before treatment with the acrylamidase.
  • the final content of acrylamide monomer in the ⁇ ubstantially dry particles is reduced to below measurable level ⁇ .
  • aqueous polyacrylamide gel particles are produced which are contaminated with acrylamide monomer at a level of at least 200ppm.
  • acrylamidase enzyme which has a Km for acrylamide of not more than 10 mM whilst the particles are at a temperature of 50 to 95°C.
  • the aqueous gel particles are then held in the cold zone of a fluid bed dryer at a temperature of from 20 to 70 °C for not more than 30 minutes and then passed to a drying stage in the hot zone of a fluid bed dryer and ⁇ ubjected in that stage to a temperature of at least 45°C, preferably at least 50 or 60°C, ⁇ o a ⁇ to produce ⁇ ubstantially dry particles of polyacrylamide.
  • thi ⁇ process also the polyacrylamide i ⁇ provided at a pH of from 2.5 to 5.0 and is not subjected to any substantial pH adjustment before treatment with the acrylamidase. In this proces ⁇ the level ⁇ of residual acrylamide are reduced to below lOOppm.
  • the polyacrylamide is contacted with the acrylamidase enzyme.
  • acrylamidase is applied in the form of a liquid su ⁇ pen ⁇ ion or solution.
  • it may be applied in the form of an aqueous suspension of acrylamidase or as a rever ⁇ e phase emulsion of acrylamidase.
  • the acrylamidase may be applied in the pure (molecular) form, having been ⁇ eparated from the microorganism by which it was produced.
  • bacterial cell ⁇ and/or cell debris eg as a pa ⁇ te, which contain an acrylamida ⁇ e enzyme which can reduce acrylamidase level ⁇ , for instance whole cell form.
  • Cells and/or cell debris may be used in immobilised form, if appropriate, or preferably in free cell form. Immobilisation may be in any suitable known manner e.g. in a polyacrylamide matrix. Permeabilised cell ⁇ can be used.
  • acrylamidase in pure or bacterial cell form may be sprayed in a carrier liquid onto the polyacrylamide particles.
  • the acrylamidase may be an enzyme which has optimum activity at pH 7 or some other non-acid pH, but has extremely high activity at its optimum, so that even activity at a non-optimum acid pH is acceptable.
  • amidase enzyme is one which has optimum activity at an acid pH, or retains substantial activity at acid pH, in particular as described in our co-pending application number ... (reference 60/3585/03) filed today and claiming priority from GB 9716764.7. Any of the acrylamidase enzymes and microorganisms discu ⁇ sed in that application may be used in the present proces ⁇ .
  • the acrylamida ⁇ e enzyme u ⁇ ed in the process is al ⁇ o tolerant to adipic acid and ha ⁇ activity at pH 4.0 in the pre ⁇ ence of 15 mM adipic acid which is at lea ⁇ t 30% of it ⁇ acrylamidase activity (measured by the adipic acid activity assay described below) mea ⁇ ured at pH 4.0 in the ab ⁇ ence of adipic acid.
  • Such enzyme ⁇ are particularly desirable for processes of the invention in which the polyacrylamide (especially if cationic) has been produced in the presence of adipic acid, for instance 0.5 to 10% adipic acid, in particular 0.5 or 1 to 5% adipic acid, based on total solids (ie monomer plu ⁇ adipic acid) .
  • adipic acid for instance 0.5 to 10% adipic acid, in particular 0.5 or 1 to 5% adipic acid, based on total solids (ie monomer plu ⁇ adipic acid) .
  • adipic acid for non-adipic acid tolerant enzyme ⁇ other buffer acid ⁇ can be used in these amounts.
  • Preferred enzymes are tolerant to succinic acid under the ⁇ ame condition ⁇ and thi ⁇ can al ⁇ o be u ⁇ ed in the amount ⁇ above.
  • the acrylamidase enzyme of the invention has a low Km for acrylamide, for instance below
  • Km is Km for acrylamide measured at pH 4.0.
  • microorganisms and the acrylamida ⁇ e enzyme ⁇ they produce are those described in our co-pending application number ... (reference 60/3585/03) filed today mentioned above.
  • Rhodococcus species deposited (as Rhodococcus species) at the National Collections of Industrial and Marine Bacteria (NCIMB) , 23 Saint Machar Drive, Aberdeen AB2 1RY , Scotland, UK on 14 July 1995 (by Dr Jonathan Hughes of Allied Colloids Ltd, P 0 Box 38, Low Moor, Bradford, West York ⁇ hire, BD12 OJZ, England, and on behalf of Allied Colloids Ltd) , under the provision ⁇ of the Budape ⁇ t Treaty and having deposit number NCIMB 40755. We believe this microorganism i ⁇ of the ⁇ pecie ⁇ Rhodococcus erythropolis.
  • Thi ⁇ enzyme i ⁇ particularly u ⁇ eful in the proce ⁇ of the invention when the polyacrylamide has not been made in the presence of significant amounts of adipic acid (eg if it is a non-ionic polyacrylamide) since it does not perform well in the presence of adipic acid.
  • adipic acid eg if it is a non-ionic polyacrylamide
  • suitable buffer ⁇ for polyacrylamide production include acetic acid, glutaric acid, citric acid and mixtures thereof .
  • This microorganism produces an acrylamidase which show ⁇ Km for acrylamide for 6 mM at pH 4.0.
  • Thi ⁇ microorganism produces an amidase which has activity at pH 4.0 which is about 65% of its activity and pH 7.0.
  • pH 4 acrylamidase activity test protocol given below it gives the following results: Rhodococcus NCIMB 40755 pH Specific Activity (U/g) Relative Activity (%) 4 2 , 506 ' 65
  • a further useful acrylamidase enzyme is produced by the Rhodococcus erythropolis strain deposited (as Rhodococcus erythropolis) at NCIMB under the provisions of the Budapest Treaty on 5 August 1997 (al ⁇ o by Dr Jonathan Hughe ⁇ of Allied Colloid ⁇ Ltd and on behalf of Allied Colloid ⁇ Ltd), and under the number NCIMB 40889.
  • Thi ⁇ microorgani ⁇ m produce ⁇ an acrylamida ⁇ e enzyme which retain ⁇ at pH 4 about 91% of it ⁇ acrylamida ⁇ e activity at pH 7.
  • This microorganism produces an acrylamidase enzyme which shows Km for acrylamide of 11.6 mM at pH 4.0.
  • the cell wall diamino acid is meso-DAP .
  • the fatty acid ⁇ pre ⁇ ent are straight chain saturated and unsaturated fatty acids together with branched chain acid having the methyl group on carbon 10; in particular 10 methyloctadecanoic acid (tuberculo ⁇ tearic acid) .
  • ND Not determined.
  • the acrylamidase activity is measured by the addition of an amida ⁇ e active cell suspension under the following standard conditions: in pH 7 (50 mM sodium phosphate buffer) or pH 4 (60 mM citric acid/77 mM disodium hydrogen phosphate buffer) or pH 5 (48 mM citric acid/103 mM disodium hydrogen phosphate buffer) , 50 mM (3554 ppm) acrylamide at 30°C.
  • One unit (U) of amidase activity hydrolyse ⁇ 1 micromole of acrylamide per minute under the above condition ⁇ .
  • the specific activity is the amount of units of activity present per dry gram of cell material.
  • the relative activity is the % activity relative to activity at pH 7. For Km the same conditions are u ⁇ ed except that the concentration of acrylamide i ⁇ varied.
  • adipic acid activity a ⁇ ay i ⁇ measured as follows: To an assay mixture at pH 4 as described for measurement of activity at pH 4 and pH 7 is added adipic acid to give the concentrations required. Cell su ⁇ pen ⁇ ion i ⁇ then added to the assay mixture. The amidase activity of each suspension is then measured. The relative activity is % activity relative to activity in the absence of adipic acid.
  • the invention can be applied to the production of cationic polyacrylamides.
  • the ⁇ e can be produced at pH 2 to
  • any of the feature ⁇ of the invention di ⁇ cu ⁇ ed above are applicable to treatment of non-ionic polyacrylamide ⁇ .
  • the amount of adipic acid buffer is preferably 0.5 to 5%, more preferably about 0.5 to 2%.
  • Treatment of the wet gel with enzyme was carried out by contracting it with a suspension of cells containing amidase, in 0.9% ⁇ aline solution or water.
  • the activity of the Amidase was taken to be 1250 unit ⁇ /g.
  • the volume of Amidase (ie no. of units) to be added was calculated on the weight of the dry polymer present.
  • the treated gel was sealed in a plastic bag and left at room temperature for 30 minutes before being dried.
  • Polymer A (homopolymer of acrylamide, IV 20 dl/g) Effect of Adipic Acid Levels on Treatment
  • Polyacrylamide gel ⁇ with varying levels of Adipic acid were prepared at pH 4. 200 ppm AZDN (azodiisobutyronitrile) and 50 ppm VA044 (2,2 '-azobi ⁇ f 2- (2-imidazolin-2-yl) propane] dihydrochloric acid) were used as thermal initiators with 12 ppm KBr0 3 and 6 ppm Na 2 S0 3 as redox initiator ⁇ .
  • AZDN azodiisobutyronitrile
  • VA044 2,2 '-azobi ⁇ f 2- (2-imidazolin-2-yl) propane] dihydrochloric acid
  • Polymer B (about 74 wt% acrylamide/about 22 wt%
  • 100 ppm AZDN and 50 ppm VA044 were used as thermal initiators with 12 ppm KBr0 3 and 6 ppm Na 2 S0 3 as redox initiators .
  • Initiator levels were as those in the previous Example.
  • Monomer solution ⁇ (a ⁇ detailed in the text) containing 100 ppm Tetralon B were initiated from 0°C after dega ⁇ ing with nitrogen.
  • Fresh ⁇ olution was prepared for each treatment.
  • the treated gel was sealed in a plastic bag and left at room temperature for the required period of time before being dried.
  • amida ⁇ e used was that produced by the microorgani ⁇ m NCIMB 40755. After treatment each dried ⁇ ample wa ⁇ analy ⁇ ed for free acrylamide levels.
  • Polyacrylamide gel polymers were produced at pH 4 , 5 and 6.
  • the gels did not contain either Adipic Acid or Urea.
  • the gels prepared at pH 4 contained 25 ppm VA044 as a thermal initiator with varying levels of KBr0 3 and Na 2 S0 3 a ⁇ redox initiator ⁇ .
  • Tho ⁇ e gels prepared at pH 5 and 6 used the t-BHP/Na 2 S0 3 initiation system. All gels prepared contained 200 ppm AZDN as thermal initiator. 100 g minced portions of wet gel were treated with 10 and 25 units/g dry polymer Amidase and left for 30 minutes at room temperature before drying.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Preparation Of Compounds By Using Micro-Organisms (AREA)
  • Immobilizing And Processing Of Enzymes And Microorganisms (AREA)

Abstract

L'invention a pour objet des procédés destinés à la production de poly(méth)acrylamide cationique ou non-ionique avec un niveau peu élevé de contamination par le monomère (méth)acrylamide. Selon ces procédés, on fournit du poly(méth)acrylamide à un pH compris entre 2,0 et 5,0, contaminé par le monomère (méth)acrylamide à un niveau égal ou supérieur à 200 mg/l, et on le met en contact avec un enzyme acrylamidase, pratiquement sans ajuster le pH. L'enzyme acrylamidase fait descendre le monomère (méth)acrylamide à un niveau inférieur à 100 mg/l.
PCT/GB1998/002362 1997-08-07 1998-08-06 Procedes de purification de polymeres Ceased WO1999007748A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU86398/98A AU8639898A (en) 1997-08-07 1998-08-06 Polymer purification processes

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9716767.0 1997-08-07
GBGB9716767.0A GB9716767D0 (en) 1997-08-07 1997-08-07 Polymer purification processes

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WO1999007748A1 true WO1999007748A1 (fr) 1999-02-18

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PCT/GB1998/002362 Ceased WO1999007748A1 (fr) 1997-08-07 1998-08-06 Procedes de purification de polymeres

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AU (1) AU8639898A (fr)
GB (1) GB9716767D0 (fr)
WO (1) WO1999007748A1 (fr)
ZA (1) ZA987138B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999067300A1 (fr) * 1998-06-25 1999-12-29 Cytec Technology Corporation Procedes d'extraction de composes monomeres d'amides indesirables a partir de preparations de polyamides
US6132985A (en) * 1996-12-18 2000-10-17 Cytec Technology Corporation Methods for the detoxification of nitrile and/or amide compounds

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0272025A2 (fr) * 1986-12-16 1988-06-22 Zeneca Limited Procédé de décomposition de l'acrylamide
WO1997006248A1 (fr) * 1995-08-09 1997-02-20 Allied Colloids Limited Procedes de production d'amidase
WO1997029136A1 (fr) * 1996-02-07 1997-08-14 Allied Colloids Limited Procedes pour la production de particules de polyacrylamide

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0272025A2 (fr) * 1986-12-16 1988-06-22 Zeneca Limited Procédé de décomposition de l'acrylamide
WO1997006248A1 (fr) * 1995-08-09 1997-02-20 Allied Colloids Limited Procedes de production d'amidase
WO1997029136A1 (fr) * 1996-02-07 1997-08-14 Allied Colloids Limited Procedes pour la production de particules de polyacrylamide

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6132985A (en) * 1996-12-18 2000-10-17 Cytec Technology Corporation Methods for the detoxification of nitrile and/or amide compounds
WO1999067300A1 (fr) * 1998-06-25 1999-12-29 Cytec Technology Corporation Procedes d'extraction de composes monomeres d'amides indesirables a partir de preparations de polyamides

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ZA987138B (en) 1999-08-10
GB9716767D0 (en) 1997-10-15
AU8639898A (en) 1999-03-01

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