Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F9/00—Multistage treatment of water, waste water or sewage
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/24—Treatment of water, waste water, or sewage by flotation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
  • C02F1/56—Macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/26—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof
  • C02F2103/28—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof from the paper or cellulose industry
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S210/00—Liquid purification or separation
  • Y10S210/902—Materials removed
  • Y10S210/917—Color
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S210/00—Liquid purification or separation
  • Y10S210/928—Paper mill waste, e.g. white water, black liquor treated

Definitions

• the invention relates to the clarification of deinking process waters which result from the recycling of paper stocks. More specifically, the present invention relates to the use of hydrophilic dispersion copolymers of diallyl-N,N- disubstituted ammonium halide and (meth)acrylamide as water clarifying agents for deinking influents.
• a preferred copolymer is formed from diallyldimethylammonium chloride (DADMAC) and acrylamide (AcAm).
• Recycled paper is increasingly used as a pulp source.
• One of the major pulping steps involves removal of the ink from any source of printed recycled paper.
• Large volumes of water are required for the ink removal process and its clean-up is accomplished using a solids/liquid separation unit operation.
• Dissolved air flotation (DAF) is commonly used.
• Dissolved air flotation is a solids-removal process where fine air bubbles become attached to the suspended particles, thus reducing the density of individual particles and causing them to float to the surface.
• the separated solids then form a floating layer that is a mixture of solids and air bubbles.
• the buoyant force exerted by the entrapped air also acts to compact the solids into a smaller volume before the floating layer is skimmed off.
• Air is usually introduced to the inflowing ink-laden water via a pressurized mixing chamber.
• the supersaturated solution releases the air in the form of very fine bubbles which become attached to the suspended particles.
• a clarification aid must be added along with the air. Flotation methods can achieve high levels of suspended solids removal, up to 98%.
• Recycle mills are most frequently located in the metropolitan areas where an emphasis on closing the water cycle of the mill is great. Consequently, effective clean-up of the deinking wash waters becomes important because reuse of the water generated e.g. from a DAF, can lead to reduced sheet quality such as brightness. Also, if these waters are used for other purposes, minimizing the amounts of BOD/-COD and suspended solids is desirable.
• Clarification chemicals are typically utilized in conjunction with mechanical clarifiers for the removal of solids from the process water stream.
• the clarification chemicals coagulate and/or flocculate the suspended solids into larger particles, which can then be removed from the process stream by gravitational settling or flotation.
• Clarification generally refers to the removal of nonsettleable material by coagulation, flocculation and sedimentation.
• Coagulation is the process of destabilization by charge neutralization. Once neutralized, particles no longer repel each other and can be brought together. Coagulation is necessary for removal of colloidal sized suspended matter.
• Flocculation is the process of bringing together the destabilized, "coagulated" particles to form a larger agglomeration or floe.
• Typical conventional cationic coagulants are poly(diallyldimethyl ammonium chloride), amphoteric diallyldimethyl ammonium chloride/acrylic acid containing copolymers, condensation polymers of ethylene dichloride/ammonia or dimethylamine/epichlorohydrin.
• Conventional acryiamide-based floccuiants have been utilized to assist in the solid/liquid separation.
• novel copolymers of poly(diallyldimethylammonium chloride/3-acrylamido-3- methylbutanoic acid) are disclosed in U.S. Patent No.
• the preferred polymer of the invention is a hydrophilic dispersion copolymer of diallyldimethyl ammonium chloride (DADMAC) and (meth)acrylamide - a single treatment agent.
• DMDMAC diallyldimethyl ammonium chloride
• the advantage of the invention disclosed herein is that it is a method which employs a dispersion polymer which is the sole treatment agent. Though other treatment agents may be added as adjuncts, they are not required for activity.
• Another advantage of this invention is that the use of these dispersion polymers affords removal of particulate materials without the unwanted addition of oils and surfactants contained in conventional latex polymers. Moreover, these polymers require no inverter system and can be introduced to the paper process stream using simple feeding equipment.
• the invention comprises a method for clarifying ink-ladened water obtained from the recycling of paper stocks by treating said water with a hydrophilic dispersion polymer.
• the hydrophilic dispersion polymer comprises: (a) cationic monomer diallyl-N,N-disubstituted ammonium halide and (b) a second monomer represented by (meth)acrylamide (in an aqueous solution of a polyvalent anionic salt), wherein the polymerization is carried out in the presence of a dispersant.
• Resultant from the addition of the polymers is a clarified process water stream and highly flocculated solids, the latter being readily handled by ordinary solid/liquid separation processes, such as a dissolved air flotation method.
• the invention comprises a method for clarifying ink-ladened water obtained from the recycling of paper stocks by treating said water with a hydrophilic dispersion polymer.
• the hydrophilic dispersion polymer of the invention is a copolymer of diallyl -N,N-disubstituted ammonium halide cationic monomer and (meth)acrylamide. It has been found that the polymer described above confers advantages for use in a papermaking process. Specifically, the hydrophilic dispersion polymers of the invention show improved or equal activity with respect to deinking process water clarification as compared to a typical mill treatment program. The use of these polymers affords removal of particulate materials without the unwanted addition of oils and surfactants contained in conventional latex polymers. Additionally, these flocculants require no inverter system and can be introduced to the paper process stream using simple feeding equipment.
• dispersion polymers Another advantage concerns the mode of addition of the dispersion polymers.
• conventional water-soluble polymers are now commercially available in a powder form. Prior to use, one must dissolve the polymeric powder in an aqueous medium for actual application. The polymer swells in aqueous medium, and the dispersed particles flocculate. It is typically very difficult to dissolve the conventional polymers in an aqueous medium.
• the dispersion polymers of this invention by their nature, avoid dissolution-related problems.
• dispersion copolymers formed from DADMAC and acrylamide have a more advantageous flexibility in that they may be used as the sole polymeric treatment, replacing the conventional dual polymer program which requires both a conventional coagulant and a flocculant.
• aqueous dispersion in accordance with the present invention if required in the form of an aqueous solution resulting from dilution with water, can be advantageously used in a number of technological fields as flocculating agents, thickeners, soil conditioners, adhesives, food additives, dispersants, detergents, additives for medicines or cosmetics, among others.
• Example 1 outlines the process for preparing the copolymer at various ratios of the monomer components in the range of from about 1 :99 to about 99:1 of acrylamide type monomer to diallyl-N,N-disubstituted ammonium halide.
• acrylamide type monomer to diallyl-N,N-disubstituted ammonium halide.
• the di-substitutents of the monomer may be C-, - C 20 alkyl groups, aryl groups, alkylaryl groups or arylalkyl groups.
• each of the di-substituents can be a different group.
• one intended halide is N-methyl-N-ethyl-N,N-diallyl ammonium chloride.
• a specific example of one applicable halide is DADMAC.
• the amount of diallyldimethyl ammonium chloride present in the copolymer is from about 5 mole percent to about 30 mole percent.
• Diallyl-N,N-disubstituted ammonium halides, especially diallyldimethyl ammonium chloride are well- known and commercially available from a variety of sources.
• the counterion may also be bromide, sulfate, phosphate, monohydrogen phosphate, and nitrate among others.
• One method for the preparation of DADMAC is detailed in U. S. Patent No. 4,151 ,202, the disclosure of which is hereinafter incorporated by reference into this specification.
• substituted (meth)acrylamide monomers may have either straight chained or branched alkyl groups.
• Applicable monomers include, but are not limited to ethyl hexyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide, dimethylaminohydroxypropyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-tert-butyl (meth)acrylamide, C C 10 N-alkyl acrylamide, C C 10 N-alkyl methacrylamide, N-aryl acrylamide, N-aryl methacrylamide, N-arylalkyl acrylamide, N-isopropyl (meth)acrylamide, N,N-dimethylacryiamide (meth)acrylamide, C-, - C 10 N,N-dialkyl acrylamide, C C 10 N, N-dialkyl methacrylamide, N,-N-diaryl
• the polyvalent anionic salt to be incorporated in the aqueous solution according to the present invention is suitably a sulfate, a phosphate or a mixture thereof.
• Preferable salts include ammonium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, ammonium hydrogen phosphate, sodium hydrogen phosphate and potassium hydrogen, phosphate.
• these salts may be each used as an aqueous solution thereof having a concentration of 15% or above.
• a dispersant polymer is present in the aqueous anionic salt solution in which the polymerization of the above monomers occurs.
• the dispersant polymer is a water-soluble high molecular weight cationic polymer.
• the dispersant polymer is preferably soluble in the above-mentioned aqueous salt solution.
• the dispersant polymer is preferably used in an amount of from 1 to 10% by weight based on the total weight of the monomers.
• the dispersant polymer is composed of 20 mole % or more of cationic monomer units of diallyl disubstituted ammonium halide or N,N-dialkyl- aminoethyl(meth)acrylates and their quaternary salts.
• the residual mole % is acrylamide or methacrylamide.
• the performance of the dispersant is not greatly affected by molecular weight.
• the molecular weight of the dispersant is preferably in the range of 10,000 to 10,000,000.
• Prefered dispersants are homopolymers of diallyldimethyl ammonium chloride, dimethylaminoethylacrylate methyl chloride quaternary salt and dimethylaminoethylmethacrylate methyl chloride quaternary salt.
• a multifunctional alcohol such as glycerin or polyethylene glycol is coexistent in the polymerization system. The deposition of the fine particles is smoothly carried out in the presence of these alcohols.
• polysaccharides such as starch, dextran, carbomethoxy cellulose and pullulan among others can also be used as stabilizers either solely, or in conjunction with other organic cationic flocculants.
• a usual water-soluble radical-forming agent can be employed, but preferably water-soluble azo compounds such as 2,2'- azobis(2-amidinopropane) hydrochloride and 2,2'-azobis(N,N'- dimethyleneisobutylamine) hydrochloride are used.
• water-soluble azo compounds such as 2,2'- azobis(2-amidinopropane) hydrochloride and 2,2'-azobis(N,N'- dimethyleneisobutylamine) hydrochloride are used.
• a seed polymer is added before the beginning of the polymerization of the above monomers for the purpose of obtaining a fine dispersion.
• the seed polymer is a water- soluble cationic polymer insoluble in the aqueous solution of the polyvalent anion salt.
• the seed polymer is preferably a polymer prepared from the above monomer mixture by the process described herein. Nevertheless, the monomer composition of the seed polymer need not always be equal to that of the water-soluble cationic polymer formed during polymerization. However, like the water-soluble polymer formed during polymerization, the seed polymer should contain at least 5 mole percent of cationic monomer units of diallyldimethylammonium halide.
• the seed polymer used in one polymerization reaction is the water- soluble polymer prepared in a previous reaction which used the same monomer mixture.
• An aspect of this invention is a method for clarifying paper process water containing ink and other impurities, comprising the steps of: a) treating said process water with an effective turbidity-reducing amount of a hydrophilic dispersion polymer resulting from polymerization of i.) a cationic monomer diallyl-N,N-disubstituted ammonium halide wherein the substituents of said disubstituted ammonium halide are selected from the group consisting of C 1 -C 20 alkyl groups, aryl groups, alkylaryl groups and arylalkyl groups ii. a second monomer of the formula
• R ⁇ nd R 2 are selected from the group consisting of hydrogen, CpC ⁇ alkyl groups, aryl groups and alkylaryl groups;
• R 3 is selected from the group consisting of hydrogen and methyl groups and
• R 4 and R 5 are selected from the group consisting of C C-, 0 straight chain or branched alkylene groups and hydrogen, in an aqueous solution of a polyvalent anionic salt wherein said polymerization is carried out in the presence of a dispersant; b) allowing the treated process water of step a) to separate into a solid ink and other impurity containing layer and a clarified liquid layer; and c) recovering said separated layers by dissolved air flotation.
• the cationic monomer may be diallyldimethyl ammonium chloride and said second monomer may be acrylamide.
• the hydrophilic dispersion polymer may have a cationic charge of from about 1 mol % to about 30 mol %.
• conventional coagulants conventional flocculants, alum, or a combination thereof may also be utilized as adjuncts with the dispersion polymers, though it must be emphasized that the dispersion polymer does not require any adjunct for optimization of activity.
• the range of intrinsic viscosities for the hydrophilic dispersion polymers of the invention is from about 0.5 to about 10 dl/g, preferably from about 1.5 to about 8.5 dl/g and most preferably from about 2.5 to about 7.5 dl/g.
• the preferred dose is from about 0.5 to about 500 ppm.
• the preferred polymer of the invention is a copolymer of diallyldimethyl ammonium chloride cationic monomer and (meth)acrylamide (AcAm) which has the unique ability to act as either a coagulant or flocculant in papermaking systems.
• the polymer has an intrinsic viscosity of from about 0.5 to about 10 deciliters per gram (dl/g), most preferably from about 2.5 to about 7.5 dl/g.
• the polymer is believed to cause the aggregation of neutralized colloidal particles which are suspended in the paper process water stream. Aggregation is the result of either entrapping agents (i.e., inorganic flocculants) or bonding agents (i.e., organic flocculants) bringing the neutralized particles together.
• entrapping agents i.e., inorganic flocculants
• bonding agents i.e., organic flocculants
• coagulants are preferably added to the system in solution form prior to the DAF unit while the flocculants are added to the DAF unit following dissolved air injection.
• the polymers of the instant invention may be added in an effective amount, generally between about 0.5-100 ppm. However, as is understood by those skilled in the art, the amount of the polymer necessary will be dependant upon the nature of the DAF influent at the particular mill to be treated.
• a 40.0% solutions of acrylamide (0.1769 moles)
• 161.29 grams of a 62.0% solution of DADMAC 0.6192 moles
• the mixture was heated to 48°C and 2.50 grams of a 4% solution of 2,2-azobis(2- amidinopropane) dihydrochloride and 2.50 grams of a 4% solution of 2,2- azobis(N,N -dimethylene isobutryramidine) dihydrochloride was added.
• the resulting solution was sparged with 1000 cc/min of nitrogen. After 15 minutes, polymerization began and the solution became viscous. Over the next 4 hours the temperature was maintained at 50°C and a solution containing 178.42 grams of 49.0% acrylamide (1.230 moles) and 0.2 grams of EDTA was pumped into the reactor using a syringe pump.
• the resulting polymer dispersion had a Brookfield viscosity of 4200 cps.
• the dispersion was then further reacted for 2.5 hours at a temperature of 55°C.
• the resulting polymer dispersion had a Brookfield viscosity of 3300 cps.
• To the above dispersion was added 10 grams of 99% adipic acid, 10 grams of ammonium sulfate, and 12.5 grams of a 60% aqueous solution of ammonium thiosulfte.
• composition M had a Brookfield viscosity of 1312.5 cps and contained 20% of a 50 weight percent copolymer of acrylamide and DADMAC with an intrinsic viscosity of 6.32 dl/gm in 1.0 molar NaNO 3 .
• Polymers and their respective descriptions used in this invention are summarized in Table I.
• Example 1 To determine the activity of the dispersion polymers synthesized according to the procedure of Example 1 , the following procedure was utilized. Samples of DAF influent were obtained from a Southern newsprint deinking mill. All samples were stored at 4°C and tested within five days.
• Typical jar testing methods were used to monitor polymer performance.
• conventional coagulants were prepared as 1 % (actives/products) solutions and flocculants as -0.1% (product) solutions in deionized water. Dosages reported are based on actives/product for coagulants and as product for flocculants.
• 0.1 % solutions were utilized. Samples of the deinking influent were stirred at 200 rpm (fast mix) for 3 min. wherein the coagulant was added at the beginning of the fast mix and the flocculant during the last 40 seconds of the fast mix. This was followed by a slow mix of 25 rpm for 2 minutes. The samples were allowed to settle for 5 minutes and an aliquot of the upper liquid layer was removed and diluted appropriately when required. Turbidity measurements were acquired with a HACH DR-2000 at 450 nm.
• composition M hydrophilic dispersion copolymer DADMAC/AcAm
• Tables ll-V a lower turbidity indicates that greater solids-liquids separation has been affected. Therefore, the greater the turbidity reduction, the more effective the treatment.
• Composition M can be used either as a coagulant (Table III) or a flocculant (Tables II, IV) in deinking water clarification. Turbidity reduction of the DAF influent with Composition M in a variety of programs was similar to or superior to the current Southern newsprint deinking mill.
• composition M alone (without alum) is superior to conventional treatments, and also that use of composition M in combination with alum results in a greater turbidity reduction, while reducing amount of alum required for efficiency.
• Table IV illustrates the advantages of a program containing the dispersion polymer and a flocculant in comparison to a conventional program.
• Table V compares the most effective programs in this DAF influent, illustrating the superior performance of the dispersion polymers formed from DADMAC and AcAm.

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• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)
• Physical Water Treatments (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Paper (AREA)

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Citations (4)

• 1998
  • 1998-12-03 EP EP98960685A patent/EP1137600A4/de not_active Withdrawn
  • 1998-12-03 CA CA002351855A patent/CA2351855A1/en not_active Abandoned
  • 1998-12-03 JP JP2000585166A patent/JP2002531248A/ja active Pending
  • 1998-12-03 KR KR1020017006892A patent/KR100579764B1/ko not_active IP Right Cessation
  • 1998-12-03 AU AU16227/99A patent/AU764315B2/en not_active Ceased
• 2001
  • 2001-06-01 NO NO20012713A patent/NO20012713L/no not_active Application Discontinuation

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