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WO1996040397A1 - Separation d'une teinture anionique a partir d'une solution aqueuse - Google Patents

Separation d'une teinture anionique a partir d'une solution aqueuse Download PDF

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Publication number
WO1996040397A1
WO1996040397A1 PCT/US1996/009003 US9609003W WO9640397A1 WO 1996040397 A1 WO1996040397 A1 WO 1996040397A1 US 9609003 W US9609003 W US 9609003W WO 9640397 A1 WO9640397 A1 WO 9640397A1
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WIPO (PCT)
Prior art keywords
anionic dye
aqueous solution
liquid
particles
separation particles
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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.)
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PCT/US1996/009003
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English (en)
Inventor
Robin Rogers
E. Philip Horwitz
Andrew H. Bond
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.)
Arch Development Corp
Northern Illinois University
University of Illinois at Urbana Champaign
Original Assignee
Arch Development Corp
Northern Illinois University
University of Illinois at Urbana Champaign
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Publication date
Priority claimed from US08/477,330 external-priority patent/US5603834A/en
Priority claimed from US08/478,382 external-priority patent/US5888397A/en
Priority claimed from US08/655,251 external-priority patent/US5707525A/en
Application filed by Arch Development Corp, Northern Illinois University, University of Illinois at Urbana Champaign filed Critical Arch Development Corp
Priority to AU59863/96A priority Critical patent/AU5986396A/en
Publication of WO1996040397A1 publication Critical patent/WO1996040397A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
    • B01D15/08—Selective adsorption, e.g. chromatography

Definitions

  • the present invention relates to the separation, concentration and recovery of anionic dye molecules from an aqueous solution in a solid/liquid separation process such as a chromatographic process.
  • Dye waste streams can no longer be disposed of by dilution into natural waters or sewage systems because of the biological damage or fouling of the treatment processes that may occur.
  • low concentrations of dyes are removed by relatively inefficient techniques that include reverse osmosis and/or adsorption on activated charcoal. In this treatment scheme the dyes cannot be recycled, are treated as solid wastes and are landfilled.
  • PEG poly(ethylene glycol)
  • phase-forming components PEG or salt
  • any loss of PEG or salt is of concern.
  • anionic dyes such as Chicago Sky Blue 6B rColor Index (C.I.) 24410, Direct Blue 1] , Direct Blue 71 (C.I. 23655) , Primuline (C.I. 49000, Direct Yellow 59) and Cibacron ® Brilliant Red 3B-A (C.I. 18105, Reactive Red 4), cationic dyes such as Safranine 0 (C.I. 50240), Auramine 0 (CI. 41000, Basic Yellow 2),
  • Chrysoidin CI. 11270, Basic Orange 2 and Victoria Blue B (CI. 44045, Basic Blue 26), and electrically neutral (uncharged) dyes such as Indigo (CI. 73000, Indigo Blue, Vat Blue 1) and Rhodanine (2-thioxo-4- thiazolidinone) partitioned almost quantitatively to the PEG phase in both acid (pH about 1.5-1.7) and base (pH about 9.6-9.8) conditions.
  • Indigo CI. 73000, Indigo Blue, Vat Blue 1
  • Rhodanine (2-thioxo-4- thiazolidinone partitioned almost quantitatively to the PEG phase in both acid (pH about 1.5-1.7) and base (pH about 9.6-9.8) conditions.
  • Methylene Blue CI.
  • the present invention relates to a separation and recovery process that effectively separates and recovers anionic dye molecules from an aqueous solution containing lyotropic ions.
  • the initial dye- containing solution is dilute, e.g. about 10 "3 -10 "6 molar or less, a more concentrated solution of the recovered dye can be obtained.
  • a process for separating and recovering anionic dyes from an aqueous solution is contemplated. That process comprises the steps of:
  • aqueous solution containing (i) an anionic dye and (ii) a poly(ethylene glycol) liquid/liquid biphase- forming amount of a dissolved salt (lyotropic) to form a solid/liquid phase admixture.
  • the anionic dye contains one, and preferably at least two, 5- or 6-membered aromatic rings and at least one substituent group having a pK a value equal to, or preferably, one unit below the pH value of the aqueous solution.
  • the separation particles comprise particles having a plurality of covalently bonded -X- (CH 2 CH 2 0) n -CH 2 CH 2 R groups wherein X is 0, S, NH or N- (CH 2 CH 2 0) m -R 3 where m is a number having an average value of zero to about 225, n is a number having an average value of about 15 to about 225, R 3 is hydrogen, C ⁇ -C .
  • alkyl, 2-hydroxyethyl or CH 2 CH 2 R and R is selected from the group consisting of -OH, C ⁇ C ⁇ hydrocarbyl ether having a molecular weight up to about one-tenth that of the -(CH 2 CH 2 0) n - portion, carboxylate, sulfonate, phosphonate and -NR ⁇ 2 groups where each of R 1 and R 2 is independently hydrogen, C 2 -C 3 hydroxyalkyi or Ci-Cg alkyl, or -NR X R 2 together form a 5- or 6-membered cyclic amine having zero or one oxygen atom or zero or one additional nitrogen atom in the ring.
  • the separation particles have a percent CH 2 0/mm 2 of particle surface area of greater than about 8000 and less than about 1,000,000.
  • the anionic dye-bound separation particles are contacted with a second aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of dissolved lyotropic salt to free the anionic dye molecules from the separation particles and form an aqueous solution containing free anionic dye molecules that is preferably at a higher concentration than that of the first-named aqueous solution of step (a) .
  • the anionic dye-bound separation particles are separated from the aqueous solution (liquid phase) of step (b) in the presence of an aqueous solution of a poly(ethylene glycol) liquid/liquid biphase-forming amount of a lyotropic salt to form a second solid/liquid phase admixture containing anionic dye-bound separation particles .
  • the anionic dye can contain one or more substituent anionic groups, such as arsenate, phosphonate, carboxylate and sulfonate groups, when named as an anion.
  • substituent anionic groups such as arsenate, phosphonate, carboxylate and sulfonate groups, when named as an anion.
  • the presence of at least one sulfonate substituent is particularly preferred.
  • Fig. 1 is a graph illustrating the loading, rinsing and elution (stripping) ; i.e., the separation, concentration and recovery, of Reactive Blue 4 (CI. 61205) dye molecules initially present at a concentration of 2.304xl0 '3 M in aqueous 1.5 M (NH 4 ) 2 S0 4 solution using ABEC-5K separation particles.
  • Rinsing with an aqueous solution of 3 M (NH 4 ) 2 S0 4 is indicated by the arrow at approximately 1300 fcv, whereas stripping with distilled water is noted by the vertical line at about 1380 fcv.
  • Fig. 2 is a graph similar to Fig. 1 showing data for the separation, concentration and recovery of Reactive Blue 4 dye molecules initially present at a concentration of 1.017xl0 "4 M in aqueous 5 M NH 4 C1 using ABEC-5K separation particles. Rinsing using an aqueous 5 M NH 4 C1 solution was carried out between about 283 and 311 fcv with a water strip being used between about 311 fcv, and 330 fcv. The ordinate and abscissa are as in Fig. 1.
  • Fig. 3 is a graph similar to Fig. 1 showing data for the separation, concentration and recovery of Acid Red 92 (CI. 45410) present initially at 1.22xl0 "5 M in aqueous 1.5 M (NH 4 ) 2 S0 4 solution using ABEC-5K separation particles.
  • a rinse with aqueous 3 M (NH 4 ) 2 S0 4 is indicated by the arrow at about 11,000 fcv, with a water strip occurring at about 11,050 to about 11,150 fcv.
  • the ordinate and abscissa are as in Fig. 1.
  • Fig. 4 is a graph similar to Fig. 1 showing data for the separation, concentration and recovery of Indigo Carmine (Acid Blue 74; CI. 73015) initially present at 2.342xl0 "4 M in aqueous 1.5 M (NH 4 ) 2 S0 4 using ABEC-5K separation particles.
  • a rinsing step using aqueous 3 M (NH 4 ) 2 S0 4 is shown by the vertical lines between about 410 and 460 fcv, with a distilled water strip occurring between about 460 and 490 fcv.
  • the ordinate and abscissa are as in Fig. 1.
  • Fig. 5 is another graph similar to Fig. 1 showing data for the separation, concentration and recovery of Cibacron ® Brilliant Red 3B-A (Reactive Red 4; CI. 18105) initially present at 5.388xl0 "5 M in aqueous 1.5 M (NH 4 ) 2 S0 4 using ABEC-5K separation particles.
  • a rinsing step using aqueous 3 M (NH 4 ) 2 S0 4 is indicated by the arrow at about 1500 fcv, and is followed by a water stripping step at about 1560 to 1580 fcv.
  • the ordinate and abscissa are as in Fig. 1.
  • Fig. 6 shows the results of a separation and recovery process for the inorganic chaotropic anion TcO ⁇ 1" using ABEC-5K separation particles at 22°C Counts per minute per milliliter (cpm/mL) with the exponent shown are plotted on the ordinate for
  • Fig. 7 is a graph showing D w values for Tc0 4 1_ ions in 5.9 m K 2 C0 3 at 25°C versus percent CH 2 0/mm 2 of particle surface for various particles.
  • Those particles were: Merrifield' s peptide resin used herein (darkened circle) ; ABEC-0.35K particles (darkened square); ABEC-0.75K separation particles (darkened triangle); ABEC-2K separation particles (darkened inverted triangle) ; ABEC-5K separation particles (darkened diamond) and ABEC-5.75K separation particles (darkened hexagon) .
  • the present invention has several benefits and advantages.
  • One salient benefit of the invention is that a contemplated process can concentrate a dilute dye bath by a factor of ten-fold or more.
  • An advantage of a contemplated process is that it can be used to free an aqueous dye solution of impurities such as dye precursors and reaction products. Another benefit of the invention is that a concentrated aqueous dye solution formed by a contemplated process can be used to recycle the dye for further use so that less waste dye is created.
  • Another advantage of a contemplated process is that where the produced concentrated dye solution is a waste to be disposed of, that waste solution is more concentrated than is a usually encountered waste and is consequently more easily dealt with.
  • a still further benefit of the invention from a waste standpoint is that a produced concentrated dye solution can contain the dye in water containing virtually no salts so that salts usually present in the waste stream are not a further source of pollution.
  • a contemplated process comprises the steps of:
  • aqueous solution containing (i) an anionic dye and (ii) a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotropic) to form a solid/liquid phase admixture.
  • the anionic dye contains one, and preferably at least two, 5- or 6-membered aromatic rings and at least one substituent group having a pK a value that is equal to, or preferably at least one unit below, the pH value of the aqueous solution.
  • the separation particles comprise particles having a plurality of covalently bonded -X- (CH 2 CH 2 0) n -CH 2 CH 2 R groups wherein X is O, S, NH or N- (CH 2 CH 2 0) m -R 3 where m is a number having an average value of zero to about 225, n is a number having an average value of about 15 to about 225, R 3 is hydrogen, C 1 -C 2 alkyl, 2-hydroxyethyl or CH 2 CH 2 R, and R is selected from the group consisting of -OH, C -C- L o hydrocarbyl ether having a molecular weight up to about one-tenth that of the -(CH 2 CH 2 0) n - portion, carboxylate, sulfonate, phosphonate and -NR ⁇ -R 2 groups where each of R 1 and R 2 is independently hydrogen, C 2 -C 3 hydroxyalkyi or C 1 -C 6 alkyl, or -NR
  • the anionic dye-bound separation particles are contacted with a second aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of dissolved lyotropic salt to free the anionic dye molecules from the separation particles and form an aqueous solution containing free anionic dye molecules that is preferably at a higher concentration than that of the first-named aqueous solution of step (a) .
  • the free anionic dye-containing aqueous solution of the above step is then recovered.
  • separation particles are particles that are hydrophilic and include poly(ethylene glycol) groups of a particular length and therefore molecular weight as is discussed hereinafter.
  • the particles can be quite varied in make-up, are inert to (do not noticeably react with) and are insoluble in the separation/recovery aqueous salt biphase-forming environment that can be very acidic or basic.
  • Exemplary preferred particles are the particularly preferred reacted cross-linked poly(styrene-vinyl benzyl halide) resins often called Merrifield's peptide resin or halomethylated (e.g., chloromethylated or bromomethylated) divinylbenzene cross-linked polystyrene, as well as glass or silica gel (silica-based) materials, cross-linked poly(ethylene glycol) -containing urethane or urea resins, cross-linked dextran- and agarose-based materials, and also various cross-linked acrylate esters.
  • cross-linked poly(styrene-vinyl benzyl halide) resins often called Merrifield's peptide resin or halomethylated (e.g
  • the separation particles can contain some reactive functionality such as benzyl halide groups that can react in the aqueous biphase- forming environment. However, any such reaction is minimal and does not alter the properties of the separation particles. Such separation particles are then deemed to be "inert" to their environment for the purpose of a separation and recovery as described herein.
  • the cross-linked, styrene/halomethylstyrene-based Merrifield's peptide resins are particularly preferred. These materials are available from a number of commercial sources such as Sigma Chemical Co., St. Louis, MO in several sizes and having differing amounts of cross-linking and differing amounts of replaceable chloride ion. The preparation of exemplary resins is also detailed hereinafter. Preferred commercially available materials are 200-400 mesh particles that contain about 0.4-0.9 meq chlorine/gram or about 0.9-1.5 meq chlorine/gram at one percent cross-linking and a material containing about 1 meq chlorine/gram at two percent cross-linking.
  • WCFs weight conversion factors
  • Still another group of cross-linked styrene/halomethylstyrene-based resins are so-called xero-gel resin particles that have pore properties intermediate between the Merrifield type and macroreticular resins.
  • the initial resin particles are swellable in toluene, but are insoluble in water and methanol, as are the separation particles prepared therefrom.
  • resins are prepared from about 70-75 parts by weight styrene, about 15-20 parts by weight vinylbenzyl chloride and about 0.5-5 parts by weight divinyl benzene as cross-linker.
  • An exemplary batch of separation particles having 1 percent cross ⁇ linker had a mesh size of 40-60 and a WCF of about 0.12. These separation particles are also particularly preferred as their relatively large particle sizes permit faster flow rates than do the smaller-sized Merrifield resin-based separation particles.
  • These resin particles are typically prepared by suspension polymerization using a diluent solvent such as toluene that dissolves the monomers and swells the polymerized resin.
  • Macroreticular resin particles are typically prepared using a similar polymerization but using a diluent solvent that dissolves the monomers but does not swell the polymerized resin.
  • Another useful group of similar resin particles from which separation particles can be prepared are so-called gel resins. These materials contain the same ingredients as the xero-gel particles except that no diluent solvent is utilized during the suspension polymerization of the particle monomers.
  • Merrifield's peptide resin particles or the similar macroreticular, xero-gel or gel resin particles are readily transformed into separation particles by reaction in a solvent inert to the reaction conditions with an alkali metal salt of a desired long chain PEG compound, followed by rinsing to remove any unreacted materials and the alkali metal halide reaction product.
  • the PEG-containing separation particles are therefore referred to as "reacted".
  • a Merrifield's peptide resin can also first be reacted with a shorter PEG compound such as tetraethylene glycol followed by reaction with ethylene oxide to extend the chains.
  • a shorter PEG compound such as tetraethylene glycol
  • ethylene oxide to extend the chains.
  • One such synthetic process is described in Bayer et al. , Poly(Ethylene Glycol) Chemistry: Biotechnical and Biomedical Applications. Harris, ed., Plenum Press, New York (1992) p. 325.
  • a similar reaction can be carried out using an alkanol amine such as mono- or diethanolamine followed by a chain lengthening reaction with ethylene oxide.
  • An aminomethyl Merrifield's peptide resin (Sigma) can similarly be reacted with ethylene oxide to form desired, amine-containing separation particles. Similar reactions using sodium sulfide and then ethylene oxide or 2-mercaptoethanol and then ethylene oxide can be used to form sulfur-containing separation particles.
  • Another group of solid support particles are cross-linked acrylic esters, particularly those having about 60 to about 98 weight percent glycidyl methacrylate with the remaining amount of monomer being cross-linking agent, and methyl methacrylate.
  • Methyl methacrylate at about 68 to about 48 weight percent, a cross-linker and about 30 to about 50 weight percent of a PEG-750 to -5000 methacrylate ester whose PEG portion has a formula -0- (CH 2 CH 2 0) n -CH 2 CH 2 R as is discussed hereinafter can also be copolymerized.
  • cross-linking agents for acrylate- based particles include trimethylolpropane trimethacrylate [2-ethyl-2 (2-hydroxymethyl) -1,3- propanediol trimethacrylate] , pentaerythritol triacrylate and the like as are well known.
  • a cross ⁇ linking agent is typically used at about 1 to about 5 weight percent and more preferably at about 2 to about 4 weight percent of the monomer mixture.
  • Support particles containing polymerized glycidyl methacrylate repeating units are post-reacted with an appropriate PEG compound to open the epoxy ring to form an ester-linked hydroxy-ether separation particle.
  • Support particles containing PEG ester groups are simply copolymerized with the other ingredients.
  • Glass- (silica-)based separation particles are also useful herein. These materials typically contain an amine group that is reacted with ethylene oxide or with an epichlorohydrin/PEG compound reaction product to form the desired separation particles.
  • aminopropyl controlled pore glass products having different pore sizes are available from Sigma Chemical Co., St. Louis, MO. These materials are said to have 150-250 ⁇ moles at 200-400 mesh down to 40-100 ⁇ moles at 80-120 mesh of primary amine per gram of material, with lessened activity/gram being present with increasing average pore size from 75A to 700A.
  • a preferred silica gel solid matrix can be prepared from the aminopropyl silica gel available from Sigma Chemical Co. that has about 1-2 mmoles of primary amine per gram of material. This material thus has about 5- to 10-times the loading capacity of the controlled pore glass product. This material has a size of about 200-425 mesh and an average pore size of about 150A.
  • Silica gel HPLC supports are also available from Sigma Chemical Co. having average pore diameters of about 60-80A and surface areas of about 420 to about 500 mm 2 /g. These particles are available in average particle diameters of about 5, 10, 30 and 60 microns. These silica-based particles can be converted into separation particles as discussed below.
  • Silica-based solid supports such as those discussed above are prepared from a suitable silica support such as silica gel or controlled pore glass by the reaction of an organosilicon compound with the support to covalently link an aminoalkylene group to the silica. These reactions are well known in the art. Amino-functional silanes having two or three C 1 -C 3 alkoxy groups are particularly preferred organosilicon compounds for use in such linking reactions. Silanes having a mercapto functional group and those having an acetoxy group convertible to a hydroxyl group by aminolysis after covalent linking to the silicon-based matrix are also available and can be used.
  • Preferred amino-functional silanes are ⁇ -amino-C 2 -C 6 -alkylenetri-C 1 -C 3 -alkoxy silanes.
  • Exemplary compounds include 4-aminobutyltriethoxysilane and 3-aminopropyltrimethoxysilane.
  • Other exemplary organosilanes from which a silica-based support particle can be prepared include N- (2-aminoethyl) -3- aminopropylmethyldimethoxysilane, (aminoethyl- aminomethyDphenethyltrimethoxysilane and N-(6- aminohexyl) aminopropyltrimethoxysilane.
  • a glycidylsilane such as 3-glycidoxypropyl- trimethoxysilane, (3-glycidoxypropyl)diethoxysilane or the like can also be reacted with a silica-based solid support followed by reaction with a desired PEG compound such as PEG-2000 methyl ether to form desired separation particles.
  • Hydroxyl- and mercapto-functional alkoxysilanes such as bis (2-hydroxyethyl) -3-amino- propyltriethoxysilane and 3-mercaptopropylmethyl- dimethoxysilane can also be reacted with a silica-based solid support followed by chain extension with ethylene oxide to provide useful separation particles.
  • Cross-linked dextran- and agarose-based particles are well known in the separation arts and are commercially available from Sigma Chemical Co. under trademarks SEPHADEX, SEPHACRYL, SEPHAROSE and PDX.
  • SEPHADEX polymerized glucose molecules that can be polyethoxylated with ethylene oxide to provide desired separation particles.
  • a desired PEG compound can be first reacted with epichlorohydrin and the reaction product reacted with the glucose-based particles to form desired separation particles.
  • cyanogen bromide activation can be used to add preformed PEG compounds such as the before-discussed PEG methyl ethers. See, for example Mathis et al . , J ⁇ Chromatogr. , 538 :456-461 (1991) and the citations therein.
  • Polyurethane/urea chemistry can also be utilized to prepare a desired separation particle.
  • a long chain PEG such as PEG-2000 or PEG-5000 is reacted with a di-isocyanate alone, or admixed with a polyamine or polyol to form a prepolymer.
  • Exemplary di ⁇ isocyanates, polyamines and polyols include methylenebis (4-phenylisocyanate) , toluene di-isocyanate, diethylenetriamine, triethylenetetramine, triethanolamine, N,N,N' -tri (hydroxyethyl) ethylene- diamine, N,N,N' ,N' -tetra(hydroxyethyl)ethylenediamine, and the like. That prepolymer is then reacted with C 2 -C 6 aliphatic diols or diamines to form polyurethanes and polyurea-urethanes, respectively.
  • Exemplary diols and diamines include ethylene glycol and ethylene diamine, 1,4-butanediol and 1,4-butanediamine, as well as 1, 6-hexanediol and 1, 6-hexanediamine.
  • a C ⁇ -C K , hydrocarbyl PEG 750-5000 ether as discussed herein can also be added at this stage as an end capping reagent as is well known.
  • Exemplary materials are discussed in Fong et al. , Talanta, 3_9:825 (1992) and Jones et al. , Anal. Chim. Acta. , 182:61(1986) .
  • a PEG compound as is defined above by the formula X- (CH 2 CH 2 0) n -CH 2 CH 2 R and discussed in detail hereinafter, is present on the surface of the separation particles either intrinsically as a result of the copolymerization process that formed the particle or extrinsically from a grafting reaction carried out after the particle is formed.
  • the data in hand tend to indicate that although the various solid support particles have pores, the separations contemplated here appear to operate from the outside surfaces of the particles and away from the pores. As a consequence, particles having smaller particle diameters, e.g.
  • 200-400 mesh (75-38 microns) and smaller (5-10 microns) are favored over particles having larger diameters, e.g. 80-120 mesh (180-115 micron) , because of the greater surface area per gram provided by the smaller particles.
  • porous materials having smaller pore sizes are preferred.
  • the PEG compound present on the separation particles can itself be quite varied in composition, but contains at least one poly(oxyethylene) chain [ (-CH 2 CH 2 0-) having an average molecular weight of about 700 to about 10,000, with a molecular weight of about 2,000 to about 5,000 being more preferred.
  • the PEG compound group of the separation particle corresponds to the formula -X- (CH 2 CH 2 0) n -CH 2 CH 2 R where X, n and R are defined and discussed hereinbelow.
  • n is a number having an average value of about 15 to about 225, and more preferably about 40 to about 130. It is well known that the higher molecular weight PEG compounds are usually mixtures rather than pure compounds having a single molecular weight. As a result, n, the number of ethyleneoxy repeating units, is a number that is an average number.
  • the terminal R group is selected from the group consisting of -OH, C ⁇ C ⁇ hydrocarbyl ether (alkoxy group) having a molecular weight of up to about one- tenth of the -(CH 2 CH 2 0) n - portion, carboxylate, sulfonate, phosphonate and -NR ⁇ 2 groups, where each of R 1 and R 2 is independently hydrogen, C ⁇ Cg alkyl or C 2 -C 3 hydroxyalkyi or -NR ⁇ 2 together form a 5- or 6-membered cyclic amine having zero or one oxygen atom or zero or one additional nitrogen atom in the ring.
  • Exemplary C ⁇ Cn, hydrocarbyl ether groups are well known and include alkyl, alkenyl, alkynyl and aromatic ethers.
  • Illustrative C ⁇ C K , ethers thus include methyl, which is most preferred, ethyl, isopropyl, n-butyl, cyclopentyl, octyl, decyl, 2-cyclohexenyl, 3-propenyl, phenyl, 1-naphthyl, 2-naphthyl, benzyl, phenethyl and the like ethers.
  • ether groups can also be named methoxy, ethoxy, isopropoxy, n-butoxy, cyclopentyloxy, octyloxy, decyloxy, 2-cyclohexenyloxy, 3-propenyloxy, phenoxy, 1-naphthoxy, 2-naphthoxy, enzyloxy and phenethyloxy.
  • a C x -C 6 hydrocarbyl group is a particularly preferred R group.
  • the molecular weight of a Ci-C- . -, hydrocarbyl ether can be up to about one-tenth of the weight of the -(CH 2 CH 2 0) n - portion of the PEG group.
  • n 20
  • the -(CH 2 CH 2 0) n - portion has a molecular weight of 880 (20 x 44) so that the molecular weight of R can be up to about 90, or about the weight of a phenoxy group. It is more preferred that the molecular weight of the
  • C- L -C- LO hydrocarbyl group be about 0.2 to about 2 percent of the molecular weight of the -(CH 2 CH 2 0) n - portion.
  • R 1 and R 2 portion of an -NR ⁇ 2 R group can individually and independently be hydrogen, C 1 -C 6 alkyl or C 2 -C 3 hydroxyalkyi so that R can be a primary amine
  • R 1 and R 2 groups that are C- L -Cg alkyl are as discussed before, e.g. methyl, ethyl, iso ⁇ propyl, sec-butyl, cyclopentyl and hexyl, whereas a C 2 -C 3 hydroxyalkyi group is a 2-hydroxyethyl, 2-hydroxypropyl or 3-hydroxypropyl group.
  • the nitrogen atom and the R 1 and R 2 portions of an -NR ⁇ 2 group can, together with the depicted nitrogen atom, form a cyclic amine group whose ring contains 5- or 6-members. That 5- or 6-membered ring amine group can contain only carbon atoms in addition to the depicted nitrogen, carbons plus one oxygen or carbons plus one nitrogen atom in addition to that depicted in -NR ⁇ 2 .
  • Exemplary cyclic amine groups include piperidinyl, pyrrolidinyl, imidazolyl, piperazinyl and morpholinyl groups.
  • X can be 0, S, NH or N- (CH 2 CH 2 0) I- -R 3 .
  • Use of an X group that is O, S or NH should be straightforward for the worker of ordinary skill.
  • X is most preferably 0, so that the separation particles most preferably have a plurality of covalently bonded surface -O- (CH 2 CH 2 0) n -CH 2 CH 2 R groups.
  • X is N- (CH 2 CH 2 0) m -R 3
  • two PEG groups can be present that are the same or different.
  • the - (CH 2 CH 2 0) n -CH 2 CH 2 R portion of the -X- (CH 2 CH 2 0) n -CH 2 CH 2 R group is always present, and as such, a PEG compound containing about 15 to about 225 - (CH 2 CH 2 0) - repeating groups is always linked to the surface of a separation particle.
  • X is N- (CH 2 CH 2 0) m -R 3
  • m is zero and R 3 is hydrogen
  • X reduces to -NH.
  • m can also be about 15 to about 225, and more preferably about 40 to about 130, as can n, as R 3 can be CH 2 CH 2 R so that the nitrogen atom of an N- (CH 2 CH 2 0) m -R 3 group can be substituted by two identical PEG groups.
  • R is -OH, that terminal hydroxyl can be the result of the use of poly(ethylene glycol) itself or of an ethoxylation reaction with ethylene oxide.
  • Ci-Ci- hydrocarbyl ether R group can be preformed as where a PEG-methyl ether is used as is exemplified herein, or that ether group can be formed by an end- capping reaction of particles having a hydroxyl R group with a strong non-nucleophilic base such as sodium hydride and a hydrocarbyl compound having a suitable leaving group such as a halide (e.g. chloro or bromo) or a sulfate ester such as a trifate, mesylate or tosylate grou .
  • a halide e.g. chloro or bromo
  • a sulfate ester such as a trifate, mesylate or tosylate grou .
  • Similar end-capping reactions can also be used to add the carboxylate, sulfonate, phosphonate and -NR ⁇ 2 R groups .
  • Exemplary compounds useful here include 2-chloroacetic acid, 4- (2-chloroethyl)piperidine and 1- (2-chloroethyl)pyrrolidine.
  • N- (2-chloroethyl) - succinimide or phthalimide can be similarly added to a terminal R hydroxy group followed by reaction with hydrazine to remove the phthalimide group and subsequent reaction with a Ci-Cg alkyl group having a before- described leaving group.
  • the free primary amine provided after reaction with hydrazine can be blocked with a removable blocking group such as t-butoxycarboryl (BOC) group prior to alkylation followed by removal of the BOC group to provide a desired secondary amine.
  • BOC t-butoxycarboryl
  • n for separation particles containing PEG compounds of very different chain lengths nonetheless are about 15 to 225.
  • separation particles referred to herein as ABEC-5.75K were prepared by first reacting Merrifield's peptide resin particles with PEG-5000 methyl ether to form ABEC-5K separation particles. Those separation particles were then reacted with PEG-750 methyl ether to form ABEC-5.75K separation particles.
  • the amount of a PEG compound present on the surface of a separation particle is provided by the percent CH 2 0/mm 2 of particle surface area value. That value is typically greater than about 8,000 and less than about 1,000,000, and is preferably greater than about 9,000 and less than about 20,000, particularly for the particularly preferred separation particles prepared from 200-400 mesh Merrifield's peptide resin particles. Larger values are provided where still smaller particles such as the 5 micron average diameter silica gel particles are used.
  • the percent CH 2 0/mm 2 of particle surface area (CH 2 0/mm 2 ) value is readily calculated using 13 C NMR integrals and the average particle surface area in mm 2 .
  • 13 C Resonances for carbon atoms adjacent to an etherial oxygen differ from those for carbon atoms adjacent to other carbons or other elements.
  • Merrifield' s peptide resin-based separation particles as illustrative, one can determine the solid 13 C NMR spectrum and determine a ratio of the number of CH 2 0 carbons to those provided by the initial resin. Multiplication of that ratio by 100 percent and division by the average particle surface area provides the CH 2 0/mm 2 value.
  • the exemplary CH 2 0/mm 2 values utilized hereinafter are based upon the surface area of 400 mesh particles. Similar solid phase 13 C NMR determinations can be carried out using separation particles prepared using the other before-discussed particles.
  • the separation particles are hydrophilic; i.e., wettable. Wettability of useful separation particles can be quantitatively approximated by calculation of a dry weight conversion factor (WCF) value for the particles. This value is approximate because for those separation particles that are only slightly wettable, the calculations involve small differences between large numbers, and even slight separation particle losses during manipulations can have a major impact upon the calculated WCF value. Nonetheless, WCF values can be useful in further defining useful separation particles.
  • WCF dry weight conversion factor
  • the WCF value for the separation particles is calculated by dividing the weight of dried separation particles by the weight of those particles after suspension in a specified aqueous medium under specified conditions followed by recovery and air-drying of those particles. These procedures are detailed hereinafter.
  • Useful separation particles typically exhibit WCF values of about 0.9 to about 0.01, with the particularly preferred separation particles exhibiting WCF values of about 0.1 to about 0.6.
  • the particularly preferred ABEC-2K and ABEC-5K separation particles discussed hereinafter exhibited WCF values of about 0.32 and 0.37, respectively, indicating about 68 and 63 percents hydration, respectively, after air-drying.
  • the useful, but less preferred ABEC-0.75K separation particles exhibited a WCF value of 1, indicating little, if any, post-drying hydration.
  • a component of the aqueous solution used in a contemplated process is a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt or lyotrope that is discussed hereinafter. It is well known that particular dissolved salts at particular concentrations and temperatures cause aqueous solutions of relatively high molecular weight poly(ethylene glycols) to form a liquid/liquid biphase; i.e., two distinct immiscible layers within the composition, in which one layer is relatively rich in PEG and the other is relatively rich in salt. This phenomenon is often referred to as salting out the PEG.
  • the liquid/liquid biphase formation is caused by the presence of water-soluble salts whose anion is principally responsible for forming the biphasic system.
  • the ammonium and alkali metal ions are usually the cations of choice with a given lyotropic anion because of their relatively high solubilities in aqueous solution, particularly as compared to multivalent cations.
  • Mo0 4 2" salts or other salts that can form do not precipitate. Precipitation with other cations can be minimized by pH value adjustment as is well known for individual salts.
  • aqueous liquid/liquid biphase formation is generally favored by increasing salt concentration to the point of saturation, and increasing temperature between about 20° and about 60°C
  • aqueous liquid/liquid biphase formation is favored by increasing PEG molecular weight, although aqueous liquid/liquid biphase formation is not observed with a PEG having a molecular weight of about 750 or lower.
  • aqueous liquid/liquid biphase can be observed usually by an interface that forms between the two immiscible layers and/or by turbidity of the composition on mixing.
  • the formulation of an analogous layering is presumed to occur in the aqueous environment surrounding the separation particles, but physical evidence for the existence of such formation has not yet been observed.
  • An indirect assay for the amount of an appropriate salt present in the aqueous solution is therefore used herein. That indirect assay is based on the observations (i) that salt concentrations that form aqueous poly(ethylene glycol) liquid/liquid biphases in solution are useful in a present process, and (ii) PEG- 750 that does not form such a biphase when free in solution in the presence of a biphase-forming amount of salt can be used when present covalently linked to the surface of separation particles as the sole PEG compound present in the presence of that amount of salt .
  • an aqueous poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt that is present in an aqueous solution used to contact the separation particles is an amount of a salt that causes a solution of PEG-2000 to form a biphase at a PEG-2000 concentration of about 4 to about 50 weight percent and at a temperature of 25°C
  • a lyotropic salt or lyotrope structures liquid water.
  • Biphase-formation is thus believed to be a function of the water-structure-making or lyotropic property of the salt used. See, P. Becher, Dictionary of Colloid and Surface Science, Marcel Dekker, Inc., New York, 1990 pages 95-96; Voet, Chem. Rev.. 20:169-179 (1937) .
  • Those materials that exhibit water-structure-breaking or chaotropic properties are retained on the separation particles.
  • Collins et al . Quart . Rev.
  • IO ⁇ The iodate anion, IO ⁇ " , appears to be an exception to this generality and behaves as a chaotropic anion even though it has a negative value, although IO ⁇ " may behave more lyotropically in the presence of a more chaotropic salt inasmuch as ⁇ S istr values are relative.
  • chloride anion is generally a poor lyotropic anion.
  • Sodium and ammonium chlorides do not cause biphase formation with PEG-2000 at 25°C
  • the chloride anion has a ⁇ S istr value of +12 and a Bi value of -0.005 according to Table 5.13 of Y. Marcus, Ion Solvation. John Wiley & Sons, Ltd., New York (1985) , 124-127. That Table reports that the sodium cation has a ⁇ S isCr value of -16 and a Bi value of +0.085, whereas the ammonium ion has values of +5 and -0.008, respectively, according to that text.
  • ammonium chloride when used from about 3 molar to saturation, about 30 grams/100 mL at zero degrees C (about 5.6 molar at zero degrees C) is a useful lyotrope in a contemplated process.
  • Sodium chloride when similarly used at about 3 molar to saturation, about 36 grams/100 mL at zero degrees C (about 6.2 molar at zero degrees C) is also useful herein.
  • the lyotropic character of sodium chloride is illustrated in the cloud point data for high molecular weight polyethylene oxide (PEO) reported in Ananthapadmanabhan et al . , Langmuir. 2:25-31 (1987) ; cloud point and phase separation being stated to be the same phenomenon by those authors.
  • PEO polyethylene oxide
  • a further way to characterize an aqueous poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt is that the concentration is about 0.05 molar to saturation, and the calculated Gibbs free energy of hydration ( ⁇ hyd G) of the anion is less than about -300 kJ/mole.
  • Exemplary calculated ⁇ hyd G values can be found in Marcus, J. Chem. Soc. , Faraday Trans.. JS7: 2995 (1991) .
  • biphase-forming soluble salt aqueous poly(ethylene glycol) liquid/liquid biphase-forming soluble salt (lyotrope)
  • other anions and cations can also be present, and mixtures of different biphase-forming salts can be used to provide a biphase-forming amount.
  • non- biphase-forming anions such as nitrate can be present in the aqueous solution
  • mixtures of biphase-forming anions such as hydroxide and carbonate can be used as the biphase-forming soluble salt.
  • Particularly preferred water-soluble lyotropic salts have an ammonium or alkali metal cation and an anion that is carbonate, sulfate, phosphate (each anion or mixtures of hydrogen phosphate anions) or chloride. Ammonium sulfate and ammonium chloride are most preferred.
  • the pH value of the above-discussed aqueous solution is between 0 and 14.
  • non- biphase-forming nitrate anions, as well as biphase- forming sulfate and phosphate anions can be present as their respective acids.
  • the concentration of hydroxide ion if used alone is too low to form a desired biphase, so other anions such as carbonate, phosphate or sulfate are also utilized to provide an appropriate salt concentration.
  • the pH value of the aqueous solution containing the anionic dye and poly(ethylene glycol) liquid/liquid biphase-forming amount of lyotropic salt and from which the dye is concentrated and ultimately recovered is equal to, and preferably one pH unit greater than, the highest pK a value of the anionic dye to be concentrated and recovered.
  • the aqueous solution used has a pH value 3.5, and preferably of 4.5 or greater.
  • an ammonium ion-forming functionality and an anion-forming functionality are both present in the dye molecule to be concentrated, as is the case for Ethyl Orange, a pH value equal to the pK a value of the amine/ammonium ion group is utilized as the amine/ammonium ion pK a value is typically higher than that of the anion-forming group.
  • pH and pK a assures that at least one-half of the anion-forming functional groups are ionized.
  • the preferred one unit difference between pH value and dye pK a value assures that at least 90 percent of the acid groups are ionized and that the molecule is anionic in the contacting solution. More preferably, the difference between the pK a of the most acidic anion-forming substituent group and the pH value of the aqueous solution is two units or more.
  • a dye whose concentration and recovery is contemplated by a process of this invention is an anionic dye; i.e., a dye having one or more acid substituent functionalities or the salts of such functional groups.
  • an anionic dye i.e., a dye having one or more acid substituent functionalities or the salts of such functional groups.
  • the dye ionizes with the dye structure being present in the negatively-charged, anionic, portion of the solvated molecule, as compared to the plus-charged portion.
  • An anionic dye can have one or more of several anion-forming substituent functional groups. Most usually, and preferably, at least one sulfonic acid or sulfonate functional group is present. Carboxyl and carboxylate, arsenic acid and arsenate, and phosphonic acid and phosphonate anion functionalities can also be present.
  • a contemplated anionic dye exhibits a water- solubility of about 1 to about 200 milligrams per milliliter of water (mg/mL) as noted in F. J. Green, The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Aldrich Chemical Co., Inc., Milwaukee, WI (1991) . Uncharged, neutral, dyes such as Indigo typically exhibit lower water-solubilities. Cationic dyes often exhibit water-solubilities similar to those of anionic dyes, although solubilities of the dyes examined to date have been less than about 100 mg/mL.
  • Neutral and cationic dyes typically are bound poorly by the contemplated separation particles, and/or strip poorly upon contact of the dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt.
  • This difference in behavior between anionic dyes and neutral or cationic dyes in a contemplated process is to be contrasted with the similar partitioning properties exhibited by the same three dye types observed in liquid/liquid biphase partition studies reported by Rogers et al. in "Value Adding Through Solvent Extraction" , Proceedings of ISEC ' 96, Shellcross et al. eds., The University of Melbourne, Parkville, Victoria, Australia, Vol.2:1537- 1542 (1996) .
  • the dyes discussed herein can have many names, including proper chemical names as well as tradenames and generic names, much like drugs.
  • the names used herein are typically the generic name used by the Color Index, The Society of Dyers and Colourists, Bradford, England, Third Edition, Fourth Revision (1992) .
  • the Color Index (CI.) number and tradename are also often used.
  • a contemplated dye contains one, and preferably at least two, aromatic rings that contain 5- or 6-members in each ring.
  • An exemplary ring can be an isolated aromatic ring such as a phenyl or a pyrazolone ring, or can be part of a fused ring system as is present in an indigoid ring system, anthraquinone ring system, naphthalene ring system or the like.
  • the aromatic rings can be completely carbonaceous, or can contain nitrogen, oxygen or sulfur atoms.
  • exemplary heteroatom-containing anionic dyes include the nitrogen-containing substituted triazines such as Reactive Blue 4 (CI. 61205) or indigoid rings as in Indigo Carmine (CI. 73015, Acid Blue 74) .
  • An exemplary sulfur-containing ring system can be found in Primuline (CI. 49000, Direct Yellow 59)
  • an oxygen-containing ring system can be exemplified by Fluorescein (CI. 45350, Acid Yellow 73) .
  • a dye utilized in a contemplated process is an anionic or acid dye. Thus, the dye is at least 50 percent ionized at the pH value utilized in the process.
  • the preferred anionic functional group is the sulfonate (-SO " ) group, and at least one such group is present in preferred practice, with the presence of two or more such groups being more preferred.
  • Other functional groups, as anions that can also be present along with or in place of a preferred sulfonate group include carboxylate (-CO/ " ) , phosphonate (-P0 3 H 1" ) , arsenate (-As0 3 H 1_ ) and the hydroxide group of a phenoxide (-0 1" ) .
  • a preferred anionic dye absorbs light in the visible spectrum and therefore exhibits a color.
  • a contemplated dye need not, however, exhibit a color and can instead fluoresce, phosphoresce or simply absorb ultraviolet light with a ⁇ . ⁇ at about 290 nm to the visible; i.e., about 400 nm.
  • Salicylic acid is exemplary of the latter dye materials. Table 2, below, lists several useful dyes and their anionic functional groups.
  • the before- described separation particles are contacted with the before-described anionic dye-containing aqueous solution.
  • This contacting is an admixing manipulation and can occur in any vessel, and constitutes what can also be termed a loading phase of the process.
  • a laboratory vessel such as a beaker or flask.
  • the contacting is carried out in a chromatography column of an appropriate size for the contemplated separation.
  • Chromatography columns are well known in the art and are generally cylindrical, have an inlet means for adding an eluting solvent at or near one end, an outlet means for egress of solvent at or near the other end, and a means for maintaining the separation particles between the inlet means and outlet means.
  • Such columns are made of a material that is inert to the materials that are therewithin; i.e., glass, plastic such as polypropylene, or stainless steel, and can be designed to operate in any position; i.e., vertically, horizontally, or in a coil. Exemplary separations using small chromatography columns are illustrated hereinafter.
  • separation particles and anionic dye-containing aqueous salt solution can take place with the separation particles being dry or wet with water or another aqueous solution prior to contact. It is preferred, however, that the separation particles be hydrated in an aqueous solution of a poly(ethylene glycol) liquid/liquid biphase-forming salt prior to that contacting (admixing) . More preferably, that salt solution contains the same salt at about the concentration to be used for carrying out the process.
  • the separation particles can be premixed with an appropriate aqueous salt solution, typically with some agitation, for a time period sufficient for dry separation particles to hydrate (swell) .
  • the separation particles are then recovered as by decantation of the liquid or by filtration, and are then admixed with the aqueous solution containing the dye.
  • a few free column volumes (fcv) of an appropriate aqueous salt-containing solution are preferably passed through the column prior to the contacting step. Regardless of the technique used, appropriate hydration typically requires only a few minutes.
  • the contacting forms a solid/liquid phase admixture.
  • the contact is maintained for a time period sufficient for the anionic dye (chaotrope) to bind to the solid phase separation particles and form a liquid phase aqueous solution that has a reduced concentration of anionic dye molecules.
  • the aqueous solution is substantially free of anionic dye; i.e., no dye can be seen in the eluate. It is noted, however, that once the capacity of the separation particles has been exceeded and the separation particles are loaded, some anionic dye molecules "break through” and color the eluate, as can colored impurities, at which time loading of the column is terminated.
  • the solid phase anionic dye-bound separation particles are preferably separated from the liquid phase formed during the maintenance step. This separation is carried out while maintaining the anionic dye-bound separation particles in the presence of an aqueous solution of a poly(ethylene glycol) liquid/liquid biphase-forming amount of a salt.
  • the degree of this separation can be enhanced by washing the column with an aqueous solution of the same or a different poly(ethylene glycol) biphase-forming lyotropic salt used during the separation step or washing with a solution of another such salt.
  • This wash or rinse step is carried out so that impurities that may remain in the interstitial volume of the column are removed prior to stripping of the chaotropic dye anion so that a higher purity product can be obtained.
  • the column can be washed with more of that salt or one can use an aqueous solution containing 3 M (NH 4 ) 2 S0 4 or (NH 4 ) 2 C0 3 .
  • Such a wash step (separation) is preferred, but not required.
  • the aqueous liquid phase formed after the maintenance step can be decanted off or separated by filtration or the like. That physical separation is preferably followed by one or more washes with aqueous salt solution as discussed above.
  • a second solid/liquid phase admixture is formed. That second solid/liquid phase admixture contains anionic dye-bound separation particles (solid phase) that are in the presence of an aqueous solution of a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt.
  • the anionic dye molecules are freed from their bound state by contacting (admixing) the anionic dye- bound separation particles with a second aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to free the anionic dye molecules from the separation particles and form an aqueous solution containing free anionic dye molecules along with their corresponding cations.
  • a third solid/liquid phase admixture is formed where solid phase constitutes the hydrated separation particles.
  • Distilled or deionized water is a convenient second aqueous solution for this purpose.
  • This stripping solution can also contain up to 100 volume percent of a water-miscible organic solven .
  • Exemplary water-miscible organic solvents include methanol, ethanol, isopropyl alcohol, dimethyl sulfoxide, acetone, ethylene glycol, propylene glycol, acetonitrile and the like.
  • the second aqueous solution also can contain biphase-forming salts such as potassium carbonate and potassium phosphate, but the concentration of those salts is less than an aqueous poly(ethylene glycol) liquid/liquid biphase-forming amount.
  • This second aqueous solution is sometimes referred to herein as a stripping solution because of its use to strip the anionic dye from the separation particles.
  • the pH value of a stripping solution can be from about zero to about 14, but is more preferably about 6 to about 8.
  • the aqueous solution containing free anionic dye molecules is then recovered.
  • the recovered aqueous solution containing anionic dye molecules contains the dye at a concentration greater than that of the original aqueous solution that was contacted with the separation particles, when the initial dye-containing solution has a dilute concentration of dye as is discussed below.
  • the concentration difference between the original anionic dye-containing solution can depend upon a number of factors. Among those factors, the original anionic dye concentration is one of the more important, as is the absence of lyotropic salts in the strip solution.
  • concentrations of about 10- to about 1000- fold can be achieved between the original and recovered aqueous anionic dye solutions using initial dye concentrations in the 10 "3 to 10" 6 molar range, or less.
  • concentration enhancements permit unused dyes to be recovered for reuse, or permit used dyes to be disposed of more efficiently, as in the case of reactive dyes whose reactive functionality has hydrolyzed.
  • a before-described process is typically carried out at ambient room temperature. However, such a process can also be carried out at any temperature above the freezing point and below the boiling point of the aqueous solutions utilized.
  • a contemplated process is typically carried out at ambient atmospheric pressure, but can also be carried out at an elevated pressure.
  • polystyrene-based chromatographic materials were prepared with the monomethyl ether derivatives of PEG-350, PEG-750, PEG-5000, and PEG-5000+PEG-750, with most of the work being done with monomethyl ethers of PEG-350, -750, -2000 and -5000. These materials were synthesized to investigate the influence of PEG molecular weight on metal ion partitioning and aqueous biphasic behavior. These resins were prepared in a manner identical to that for Me-PEG-2000, and all afforded dirty white bead-like solids.
  • Separation particles prepared using Me-PEGs having molecular weights of 350, 750, 2000, 5000 and both 5000 and 750 are named separation particles, ABEC-0.35K, ABEC-0.75K, ABEC-2K, ABEC-5K, and ABEC-5.75K respectively.
  • a number of metal cations including Na 1+ , Cs 1+ , Ca 2+ , Sr 2+ , Mn 2+ , Co + , Cd 2+ and Tl 1+ were assayed for retention by ABEC-2K separation particles from both water and 5.05 molal (m) (NH 4 ) 2 S0 4 . None of the above metal cations was retained by the material, and this is in keeping with their behavior in liquid/liquid aqueous biphasic separations where none of those metal ions partitions to the PEG-rich phase. Because the pertechnetate anions partition to the PEG-rich phase in liquid/liquid aqueous biphasic systems without the aid of an extractant, [Rogers et al .
  • Weight distribution ratios for TcO " have been determined from (NH 4 ) 2 S0 4 , K 2 C0 3 , K 3 P0 4 , and NaOH solutions as exemplary. These salts are known as liquid/liquid biphase forming anions and cover a broad range of chemical characteristics. Weight distribution ratios for TcO/ " anions onto unmodified chloromethylated polystyrene-1-percent- divinylbenzene from both water and 5.05 m (NH 4 ) 2 S0 4 were near unity. Pertechnetate retention by ABEC-2K separation particles from water was extremely low affording a D w of only 8.7.
  • the amount of solute on the separation particles is determined by a difference method and therefore D w values less than one are difficult to obtain due to error inherent in the assay method. D w values less than 20 generally indicate little if any retention. A D w value of about 200 is maximally observed in a liquid/liquid extraction of TcO/ " ions in NaOH using 20-70 weight percent aqueous PEG-2000.
  • Separation particles denominated ABEC-0.75K showed an appreciable increase in TcO/ " anion distribution with a maximum D w of 460 at 4.08 m (NH 4 ) 2 S0 4 .
  • Pertechnetate retention started low, maximized, and then tailed from P0 4 3" , CO/ " , and S0 4 2" solutions.
  • Sodium hydroxide afforded the lowest weight distribution ratios that sharply decreased from a maximum D w of 96 at 2.78 m NaOH.
  • Separation particles ABEC-0.75K like ABEC-0.35K, had a dry weight conversion factor of 1.0. Although not as hydrophobic as ABEC-0.35K particles, this material dispersed evenly in water and is useful, but difficult to handle because it has a gummy consistency.
  • Separation particles ABEC-2K were the first material to show a behavior similar to aqueous biphasic partitioning. The potential of this material was suggested by its dry weight conversion factor, which indicated a 68.4 percent water content. Maximal D w values were 4500, 6200, 1900, and 880 from 5.05 m (NH 4 ) 2 S0 4 , 5.92 m K 2 C0 3 , 3.14 m K 3 P0 4 , and 4.41 m NaOH, respectively, were obtained using these particles. D w 's from sodium hydroxide peaked at an intermediate salt concentration (4.41 m) and then began to decrease. The remaining salts all showed a reasonable increase in weight distribution ratios, with K 2 C0 3 affording the highest D w values .
  • Weight distribution ratio profiles using ABEC-5K separation particles have the same general features as those observed for ABEC-2K particles, except that there is an increase in D w for TcO/ " anions from NaOH rather than the intermediate maxima observed for ABEC-2K particles.
  • the maximum weight distribution ratios are 7000, 19000, 5200 and 2500 from 5.05 m (NH 4 ) 2 S0 4 , 5.92 m K 2 C0 3 , 3.14 m K 3 P0 4 , and 8.33 m NaOH, respectively. These values are about two to three times those obtained with ABEC-2K particles, with the maximum D w values from the K 2 C0 3 solution as observed for ABEC-2K particles.
  • the dry weight conversion factor of 0.374 for ABEC-5K particles was higher than that for ABEC-2K particles, indicating a lower water content.
  • dilute anionic dyes and to a lesser extent neutral and cationic dyes, can be separated from other dye bath constituents, concentrated relative to the initial dilute dye-containing solution, and recovered in concentrated form. These studies also indicate that mixtures of anionic dyes can be separated from each other using a contemplated process so that one dye can be purified from another. All of the anionic dyes thus far studied in detail, about fifteen, have been successfully separated and recovered.
  • Dyes containing at least one sulfonate functional group typically provide the highest D w values and are readily stripped from the separation particles using water. Dyes that contain carboxylate and/or phenoxide functionalities and no sulfonate functionality such as FD&C Red #3 (CI.
  • a plot of D w values versus D values for several dyes provides an approximate D W :D ratio of about 60, indicating that a contemplated process using ABEC-5K is about 60 times more effective in concentrating the dye than is the PEG- containing aqueous liquid/liquid biphase used here for comparison.
  • the correlative uncertainties notwithstanding, a contemplated process provides a means whereby the dye can be readily recovered, whereas aqueous liquid/liquid biphase separations do not do so. The capacity of the separation particles was found to vary for each dye studied.
  • Anionic dyes were typically bound at about 0.3 to about 5 mmoles per gram day weight of ABEC-5K separation particles, with tetrasodium nickel phthalocyaninetetrasulfonate being bound only at about 9xl0 "3 mmoles per gram dry weight of separation particles.
  • the separation particles typically exhibited much lower capacities for cationic dyes.
  • the capacity of those same ABEC-5K separation particles for the cationic dye Ingrain Blue 1 (CI. 74240), a copper phthalocyanine derivative was about l-5xl0 "5 mmoles per gram dry weight and for
  • Auramine O (CI.41000), another cationic dye, was about 2xl0 "3 moles per gram dry weight.
  • Tetraethylene glycol, Me-PEG-350, Me-PEG-750, PEG-2000, Me-PEG-2000, Me-PEG-5000 and chloromethylated polystyrene-1-percent-divinylbenzene beads (Merrifield's peptide resin; 200-400 mesh) were obtained from Aldrich Chemical Co., Inc., Milwaukee, WI. All were used without further purification. Reagent-grade (NH 4 ) 2 S0 4 , K 2 C0 3 , K 3 P0 4 , and NaOH were used as received. The reagents and procedures for preparing the Hanford simulated waste solutions have been reported. [Rogers et al., Solvent Extr. Ion Exch.. 13:689-713 (1995)] All water was deionized using commercial deionization systems. Dye molecules were purchased from Aldrich, and were used as received.
  • Me-PEG-750 (2.25 g, 3.0 mmol), or Me-PEG-5000 (15.0 g, 3.0 mmol) was then added to the addition funnel under a positive Ar flow.
  • the same procedure was utilized in the preparation of ABEC-2K separation particles, except that a 3:1 molar excess of Me-PEG-2000 alkoxide to resin active sites was prepared with NaH (1.07 g, 45 mmol) and Me-PEG-2000 (18.0 g, 9.0 mmol) .
  • the Me-PEG-750, Me-PEG- 2000, and Me-PEG-5000 are solids that were melted into the THF in the addition funnel with the aid of a hot air gun.
  • Insoluble Copolymer Beads for Preparation of ABEC Particles Preparation A Insoluble, cross-linked copolymer beads (100 g) were prepared by suspension polymerization of 67.47 weight percent vinylbenzyl chloride, 23.03 weight percent styrene, 5.0 weight percent divinylbenzene, and 0.5 weight percent benzoyl peroxide; ethylstyrenes were also present from the technical grade divinylbenzene. To introduce porosity, an equal amount of 1:1 (w/w) mixture of toluene and dodecane was added. The entire polymerization mixture was placed in a cylindrical reactor equipped with overhead stirrer, reflux condenser and thermometer, and was heated at 60°C for one hour,
  • Insoluble, cross-linked copolymer beads (70.7 g) were obtained by suspension polymerization of 90.5 weight percent vinylbenzyl chloride, 2.0 weight percent divinylbenzene, and 0.5 weight percent benzoyl peroxide (with the ethylstyrenes present in the technical grade divinylbenzene) .
  • a nucleophilic reaction with a carbanion nucleophile indicated the presence of about
  • Preparation C Insoluble, cross-linked copolymer beads (100 g) were obtained by suspension polymerization of 2.0 weight percent of 2-ethyl- (2-hydroxymethyl) -1, 3- propanediol trimethacrylate, 97 weight percent of glycidyl methacrylate and 1.0 weight percent of benzoyl peroxide. About 1.3 mmol per gram dry weight of ring- openable epoxide groups were found upon nucleophilic reaction with a carbanion.
  • copolymer beads are prepared by suspension polymerization as follows:
  • a 1-L three-neck round-bottom flask was equipped with a mechanical stirrer and a condenser.
  • Polyvinyl alcohol (PVA; 1.5 g) was slowly added to 150 mL of deionized (DI) water with stirring. After the PVA was completely dissolved, CaCl 2 »2H 2 0 (30 g) was added. When the solution turned clear, tribasic calcium phosphate (1.5 g) was added to the mixture with further stirring. Because calcium phosphate tribasic is insoluble, the final mixture was a cloudy suspension that was stirred gently until used. The combination of PVA and calcium salts stabilizes the ultimately produced resin particles during their formation.
  • the stirring blade was adjusted to a position about half above the surface of the above-prepared aqueous phase.
  • the motor was started and set to stir at a speed of 275 rpm.
  • the organic phase was then slowly poured into the reactor.
  • the admixture was heated to 55°C in about 15 minutes.
  • the temperature was then slowly increased to 80°C at a rate 5°C/30 minutes and held at 80°C for 15 hours.
  • the reaction mixture was thereafter cooled to room temperature.
  • the condenser was replaced with a simple distillation head. Methanol (300 mL) was added and the mixture was heated to a gentle boiling condition. Three hundred mL of distillate were collected. The diluent toluene was azeotroped with water and methanol in this process. The use of methanol or ethanol minimizes foaming when the diluent solvent is being removed. After azeotropic removal of the toluene, the beads were collected, rinsed on a screen with DI water and then dried on a tray at atmospheric pressure.
  • a 5-L three-neck round-bottom flask was equipped with a mechanical stirrer, a condenser and a nitrogen gas inlet. The reaction was run under a nitrogen flow to dilute the hydrogen produced until the methanol washing step.
  • the xero-gel copolymer (50.04 g) as prepared above and then 2.5 L of tetrahydrofuran (THF) were mixed in the flask, and the mixture was stirred at room temperature for one hour. The resin was fully swollen in this hour.
  • Monomethyl-PEG-5000 (525 g) was added to the flask and the mixture was then heated to 45-50°C to dissolve the PEG.
  • the admixture was cooled to about 30°C, and 21.62 grams of NaH (60 percent pure, dispersed in mineral oil) were added very slowly. That mixture was heated at reflux for 17 hours, and then permitted to cool. After the mixture cooled to room temperature, 250 mL of methanol were added through an addition funnel over a period of 30-45 minutes to react the unreacted NaH.
  • the formed ABEC resin was then washed with 1 liter of methanol, 50 percent aqueous methanol, and water. Finally, the resin was transferred to a column and conditioned with 5 liters of DI water.
  • A-, the activity of the solution prior to contact with the resin
  • a f the activity of the solution after contact with resin
  • V volume (mL) of solution contacted with resin
  • m R mass (g) of resin
  • wcf the dry weight conversion factor relating the mass of the hydrated resin to its dry weight.
  • the D w studies were carried out in the following manner.
  • the radiotracer was added to 1.2 mL of the solution of interest, gently mixed, and a 100 ⁇ L aliquot was removed for radiometric counting to determine the initial activity of the solution (A,.) .
  • One mL of the remaining solution (V) was added to a known mass of hydrated resin (m R ) and centrifuged for one minute.
  • the solution was then stirred gently (so that the resin was just suspended in the solution) for 30 minutes, followed by one minute of centrifugation, and another 30 minutes of stirring. After one additional minute of centrifugation, the solution was pipeted away from the resin and filtered through a 45 ⁇ m pipet-tip filter so that any suspended resin would be removed.
  • a 100 ⁇ L aliquot was then removed for counting the final activity of the solution (A f ) .
  • a disposable plastic column equipped with a Luer-lock stopcock and porous plastic bed support was slurry packed with ABEC-5K separation particles in water and backwashed.
  • a porous plastic frit was placed on top of the bed to prevent its disruption during the addition of eluent.
  • the bed volume was 1.63 mL and the free column volume (fcv) was determined by 99 Mo0 4 2 ⁇ breakthrough.
  • the fcv of 0.392 mL was comparable to that obtained using a sodium breakthrough/flame test. All eluate volumes were calculated gravimetrically using the respective solution densities.
  • the ABEC-5K separation particle-containing column was equilibrated with 5.00 mL (12.8 fcv) of 5.0 M NaOH. Thereafter, 11.2 mL (28.6 fcv) of Na 2 99 Mo0 4 in 5.0 M NaOH was eluted on the column using gravity flow ( ⁇ 0.3 mL/minute) . Prior to rinsing, the reservoir was washed three times with 3 mL of K 2 C0 3 to remove residual Na 2 99 Mo0 4 . The column was rinsed of Na 2 99 Mo0 4 by elution with 4.3 mL (11.0 fcv) of 3.0 M K 2 C0 3 .
  • the total ⁇ activity of 99 Mo0 4 2" ions eluted on the column was 5.19 X 10 6 cpm.
  • the sum of the activity of 99m Tc0/ " anions stripped from the column was 1.97 x
  • Weight conversion factors that are a measure of the wettability of separation particles and figure in D w calculations are determined as follows. A sample of separation particles is hydrated in an excess of water for 30 minutes at room temperature, and then filtered on a Buchner funnel and dried in place with a stream of water-saturated air for 5 minutes at a pressure of about 660-670 torr. A portion of that air-dried material is removed, weighed and then dried in an oven at 110°C until a constant mass was obtained. The dry mass of the separation particles divided by the mass of air-dried separation particles provided the dry weight conversion factor. Each gravimetric analysis was performed in duplicate, and was repeated each time a new batch of hydrated separation particles was prepared.
  • Weight Distribution and Percent CH ⁇ O/mm 2 Surface Area D w values were determined for TcO/ " ions in 5.92 m K 2 C0 3 solution using ABEC-0.35K, ABEC-0.75K, ABEC-2K, ABEC-5K and ABEC-5.75K separation particles prepared from 200-400 mesh Merrifield's peptide resin (polystyrene-1 percent-divinylbenzene) precursor particles. The unreacted particles were also assayed.
  • Standard curves were made for each dye by preparing four solutions of known concentrations in deionized water, and determining absorbances at ⁇ -, ⁇ on a Milton Roy spectronic 21 D UV-Visible spectrophotometer.
  • ⁇ - ⁇ x Values were obtained from The Sigma-Aldrich Handbook of Stains. Dyes and Indicators. F. J. Green, Aldrich Chemical Company, Inc., Milwaukee, WI (1991), or by scanning the absorbance in the 280-800 nm region.
  • a plot of absorbance vs. concentration yields a straight line that was fit by linear regression (Sigma Plot) . This equation was then used to determine the concentration of the unknown dye solutions from their absorbance.
  • the feed solutions were prepared by adding an excess amount of dye to 1.5 M (NH 4 ) 2 S0 4 , stirring for 10 minutes, and then filtering (Whatman ® #2 filter paper) to yield a saturated dye solution. The concentration of this solution was then determined by measuring its absorbance (at ⁇ - ⁇ and using the standard curve to calculate the concentration. Small columns (Isolab Practi-columnTM 10 mm OD, 100 mm length) were prepared separately for each study. Approximately 0.5 g of ABEC-5K resin prepared as described before using Merrifield' s peptide resin were slurry-packed with water in each column.
  • the weight of resin used was converted to a dry weight by multiplying the weight of resin used by its dry weight conversion factor.
  • the dry weight conversion factor was calculated for each lot by gravimetric analysis.
  • the packed column was then sonicated for 20 minutes to ensure good packing of the resin and to prevent channeling.
  • a small porous disk was placed on top of the resin bed to hold it in place.
  • each column was equilibrated by eluting 20-25 free column volumes (fcv's) of 1.5 M (NH 4 ) 2 S0 4 .
  • the fcv was determined by 22 Na breakthrough as follows: The equilibrating solution was eluted until the solution was level with the top of the resin bed. A 22 NaCl-spiked 1.5 M (NH 4 ) 2 S0 4 solution of approximately 1 mL was then added to the column. The spiked solution was then eluted through the column, collecting 2-drop samples. The samples were then counted on a Packard Cobra IITM gamma counter. The sum of the sample volumes up to the first appearance of 22 Na activity minus the void volume yields the free column volume. The dead volume is the volume occupied from the bottom of the resin bed to the bottom of the column's stopcock. 22 Na was used in this study because it is not retained by the resin.
  • the column was then mounted on a Bio-Rad model 2110 fraction collector and the feed solution was eluted (gravity flow) at a rate of approximately 1 mL/minute, collecting approximately 3 mL samples. The flow rates typically slowed to 0.5-0.25 mL/minute as the column approached capacity.
  • the feed solution was loaded into the packed column until a strong dye color was visible in the eluate at which time a rinse solution [3 M or 1.5 M (NH 4 ) 2 SO was added to the column.
  • the column was rinsed with this solution until no dye color was visible in the eluate. (Sample volumes collected during the rinse varied from 3 mL to about 500 mL depending on the behavior of the dye.
  • the column was then stripped by eluting with deionized water, an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a lyotropic salt. During the strip, smaller sample volumes were collected (3-4 drops) . In some cases, the dye left a visible stain on the resin. For these stained columns, an additional strip with methanol was utilized to help remove the dye from the column. The identities of the staining materials have not determined, but those materials are believed to be different from the dye eluted with water.
  • the concentration of dye in all of the samples was determined by measuring absorbance at ⁇ - ⁇ x , and using the standard curve. Because the sample volumes collected were not equal, the chromatographs were plotted as the concentration of dye in the collected sample (moles/L) per mL of eluate collected vs. the total number of free column volumes eluted.
  • Capacity of the column was reached when the concentration of dye in the eluate was equal to the concentration of dye in the feed. At this point the feed solution was replaced with a 3 M (NH 4 ) 2 S0 4 rinse solution. For Basic Yellow 2 and Acid Yellow 1, the molarity was switched to 1.5 M (NH 4 ) 2 S0 4 until the dye concentration in the rinse eluate was near zero, then switched back to 3 M. The rinse eluate was monitored in the same way as the feed. When the concentration of dye in the eluate was zero, the column was stripped with deionized water. For dyes that stained the resin, a small portion (2-3 mL) of methanol was used in the strip. The concentration of dye in the strip was determined from its absorbance at ⁇ max , and the capacity was calculated as mmoles of dye per gram of dry resin.
  • the dyes obtained from a local grocery store, were packaged under the brand name McCormick Colors & Egg Dyes by McCormick & Co., Inc., Hunt Valley MD.
  • the blue, red, and yellow dyes utilized in the study contained FD&C Yellow 5 (CI. 19140), FD&C Red 40 ( I. 16035), FD&C Blue 1 ( I. 42090), and FD&C Red 3 ( I. 45430) .
  • the maximum absorptions for each dye were determined by scanning the UV/visible light range of 800-300 nm. The yellow maximum appeared at 426 nm, red at 490 nm, and blue at 630 nm.
  • the blue dye appeared to be a mixture of at least two different dyes; one with a ⁇ - ⁇ x at 630 nm (CI. 42090), another with a ⁇ m3iX at 532 nm (CI. 45430) .
  • the red and yellow maxima overlapped. However, those dyes were sufficiently separated during the column run.
  • the blue dye also had minor peaks that overlapped with the red and yellow dyes.
  • the feed solution was prepared by adding 1 drop of each food dye to 50 mL of 1.5 M (NH 4 ) 2 S0 4 .
  • the feed solution (2 mL) was added to the top of the ABEC column and eluted. A very small band of a dark green color was visible at the top of the column.
  • the column was rinsed with 24 mL of 1.5 M (NH 4 ) 2 S0 4 . During the rinse, a yellow color moved down the column about 0.1 cm.
  • the column was then stripped by elution with water, and the eluate was scanned using a UV spectrometer. During the strip, all of the color in the original light band at the top of the column was removed except for a small pink band that remained at the top of the column. The pink band (CI. 45430) was eluted with methanol. During the strip step, the yellow color eluted first, followed by the blue, and finally the red colors. In this unoptimized study, there was good separation between the yellow and blue colors. The red and blue colors were less well resolved. These separations nonetheless illustrate how a contemplated process can be used to purify anionic dyes.
  • a known amount of dye was dissolved in aqueous 1.5 M (NH 4 ) 2 S0 4 solution, and diluted to a dye concentration of about 10 "6 M with 1.5 M (NH 4 ) 2 S0 4 .
  • the absorbance of the resulting dye solution was measured with a Milton Roy Spectronic 21 D UV-Visible spectrometer using 1.5 M (NH 4 ) 2 S0 4 as reference.
  • the dye solution (3 mL) was contacted with about 0.04 g of resin and stirred for 30 minutes, centrifuged, vortexed, and centrifuged again followed by another 30 minutes of stirring, then centrifuged.
  • the solution was separated from the resin and was used for the absorption measurement.
  • the wavelength used for each dye was the ⁇ max from the The Sigman-Aldrich Handbook of Stains. Dves and Indicators.
  • the D w was calculated by the following equation:
  • a 0 is the absorbance of the dye solution before contact with resin
  • a f is the absorbance of the dye solution after contact with resin
  • V is the volume of the dye solution used to contact resin
  • m R is the mass of the resin used to contact dye solution
  • wcf is the weight conversion factor for the resin.
  • a dye solution [3 mL of about 10 "6 M in 1.5 M
  • UV-Visible spectrometer with 2.5 M (NH 4 ) 2 S0 4 as the reference.
  • the wavelength used for each dye is the ⁇ - ⁇ x from the The Sigma-Aldrich Handbook of Stains. Dyes and Indicators.
  • the distribution ratios for dyes were calculated as following:
  • [dye] p and [dye] s represent the concentration of dye in PEG-rich phase and salt-rich phase, respectively.
  • I 0 is the absorbance of the dye stock solution
  • I s is the absorbance of the salt-rich phase
  • V s and V p are the volumes of the salt-rich phase and the PEG-rich phase, respectively.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

La présente invention se rapporte à un procédé de séparation phase solide/phase liquide utilisé pour séparer et récupérer une teinture anionique à partir d'une solution aqueuse. La phase solide comprend des particules de séparation comportant des groupes poly(éthylène-glycol) liés à la surface, alors que la solution aqueuse à partir de laquelle les molécules de teinture anionique sont séparées contient une quantité, formant une biphase poly(éthylène-glycol) liquide/liquide, d'un sel lyotrope dissous. Une fois la solution aqueuse en contact avec les particules de séparation, la teinture anionique est liée aux particules. Les molécules liées de la teinture anionique se libèrent des particules de séparation lorsqu'elles entrent en contact avec une solution aqueuse qui ne contient pas une quantité, formant une biphase poly(éthylène-glycol) liquide/liquide, d'un sel lyotrope dissous, pour former une solution aqueuse de teinture anionique, dont la concentration en teinture anionique est de préférence plus élevée que celle de la solution initiale contenant de la teinture anionique.
PCT/US1996/009003 1995-06-07 1996-06-06 Separation d'une teinture anionique a partir d'une solution aqueuse Ceased WO1996040397A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU59863/96A AU5986396A (en) 1995-06-07 1996-06-06 Separating anionic dye from aqueous solution

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US08/478,382 1995-06-07
US08/477,330 1995-06-07
US08/477,330 US5603834A (en) 1995-06-07 1995-06-07 Process for recovering pertechnetate ions from an aqueous solution also containing other ions
US08/478,382 US5888397A (en) 1995-06-07 1995-06-07 Process for recovering chaotropic anions from an aqueous solution also containing other ions
US08/655,251 US5707525A (en) 1995-06-07 1996-06-05 Process for separating and recovering an anionic dye from an aqueous solution
US08/655,251 1996-06-05

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WO1996040397A1 true WO1996040397A1 (fr) 1996-12-19

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5157020A (en) * 1990-05-24 1992-10-20 Research Corporation Tech., Inc. Synthetic senescent cell antigen
US5411149A (en) * 1992-08-11 1995-05-02 Arch Development Corporation Aqueous biphasic extraction process with pH and particle control

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5157020A (en) * 1990-05-24 1992-10-20 Research Corporation Tech., Inc. Synthetic senescent cell antigen
US5411149A (en) * 1992-08-11 1995-05-02 Arch Development Corporation Aqueous biphasic extraction process with pH and particle control

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