JPWO2012114953A1 - Reverse osmosis membrane scale inhibitor and scale prevention method - Google Patents
Reverse osmosis membrane scale inhibitor and scale prevention method Download PDFInfo
- Publication number
- JPWO2012114953A1 JPWO2012114953A1 JP2012515835A JP2012515835A JPWO2012114953A1 JP WO2012114953 A1 JPWO2012114953 A1 JP WO2012114953A1 JP 2012515835 A JP2012515835 A JP 2012515835A JP 2012515835 A JP2012515835 A JP 2012515835A JP WO2012114953 A1 JPWO2012114953 A1 JP WO2012114953A1
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- Japan
- Prior art keywords
- scale
- maleic acid
- water
- scale inhibitor
- soluble polymer
- Prior art date
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- 239000002455 scale inhibitor Substances 0.000 title claims abstract description 88
- 239000012528 membrane Substances 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000001223 reverse osmosis Methods 0.000 title claims abstract description 21
- 230000002265 prevention Effects 0.000 title claims abstract description 20
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 claims abstract description 74
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 claims abstract description 56
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims abstract description 55
- 239000011976 maleic acid Substances 0.000 claims abstract description 55
- 229920003169 water-soluble polymer Polymers 0.000 claims abstract description 43
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 42
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 21
- 229920001577 copolymer Polymers 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical group CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 claims abstract description 7
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229920001444 polymaleic acid Polymers 0.000 claims abstract description 6
- JIGUQPWFLRLWPJ-UHFFFAOYSA-N Ethyl acrylate Chemical compound CCOC(=O)C=C JIGUQPWFLRLWPJ-UHFFFAOYSA-N 0.000 claims abstract description 5
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229920001897 terpolymer Polymers 0.000 claims abstract description 5
- 238000001556 precipitation Methods 0.000 claims description 25
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 15
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 15
- 239000011574 phosphorus Substances 0.000 abstract description 15
- 239000002244 precipitate Substances 0.000 abstract description 12
- 239000000047 product Substances 0.000 abstract description 10
- 230000003204 osmotic effect Effects 0.000 abstract description 8
- 239000002351 wastewater Substances 0.000 abstract description 8
- -1 for example Polymers 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 19
- 239000000178 monomer Substances 0.000 description 17
- 239000000498 cooling water Substances 0.000 description 13
- 238000001879 gelation Methods 0.000 description 11
- 238000006116 polymerization reaction Methods 0.000 description 11
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 10
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 10
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- 238000012360 testing method Methods 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
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- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 8
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 8
- 239000002253 acid Substances 0.000 description 7
- 239000007864 aqueous solution Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
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- 230000002401 inhibitory effect Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
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- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
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- BAERPNBPLZWCES-UHFFFAOYSA-N (2-hydroxy-1-phosphonoethyl)phosphonic acid Chemical compound OCC(P(O)(O)=O)P(O)(O)=O BAERPNBPLZWCES-UHFFFAOYSA-N 0.000 description 2
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 2
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 2
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- 150000003926 acrylamides Chemical class 0.000 description 2
- 125000005907 alkyl ester group Chemical group 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 239000000872 buffer Substances 0.000 description 2
- 239000001506 calcium phosphate Substances 0.000 description 2
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- 239000012986 chain transfer agent Substances 0.000 description 2
- 238000007720 emulsion polymerization reaction Methods 0.000 description 2
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- 230000005764 inhibitory process Effects 0.000 description 2
- 239000003999 initiator Substances 0.000 description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 2
- 239000000347 magnesium hydroxide Substances 0.000 description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 2
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
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- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 2
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- 230000002829 reductive effect Effects 0.000 description 2
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- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 description 2
- 235000019982 sodium hexametaphosphate Nutrition 0.000 description 2
- JQWHASGSAFIOCM-UHFFFAOYSA-M sodium periodate Chemical compound [Na+].[O-]I(=O)(=O)=O JQWHASGSAFIOCM-UHFFFAOYSA-M 0.000 description 2
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 2
- 235000019832 sodium triphosphate Nutrition 0.000 description 2
- UBXAKNTVXQMEAG-UHFFFAOYSA-L strontium sulfate Chemical compound [Sr+2].[O-]S([O-])(=O)=O UBXAKNTVXQMEAG-UHFFFAOYSA-L 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- CIHOLLKRGTVIJN-UHFFFAOYSA-N tert‐butyl hydroperoxide Chemical compound CC(C)(C)OO CIHOLLKRGTVIJN-UHFFFAOYSA-N 0.000 description 2
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- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 2
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- MGRVRXRGTBOSHW-UHFFFAOYSA-N (aminomethyl)phosphonic acid Chemical compound NCP(O)(O)=O MGRVRXRGTBOSHW-UHFFFAOYSA-N 0.000 description 1
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 1
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
- LYBIZMNPXTXVMV-UHFFFAOYSA-N propan-2-yl prop-2-enoate Chemical compound CC(C)OC(=O)C=C LYBIZMNPXTXVMV-UHFFFAOYSA-N 0.000 description 1
- KCXFHTAICRTXLI-UHFFFAOYSA-N propane-1-sulfonic acid Chemical compound CCCS(O)(=O)=O KCXFHTAICRTXLI-UHFFFAOYSA-N 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 150000003460 sulfonic acids Chemical class 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- UGZADUVQMDAIAO-UHFFFAOYSA-L zinc hydroxide Chemical compound [OH-].[OH-].[Zn+2] UGZADUVQMDAIAO-UHFFFAOYSA-L 0.000 description 1
- 229940007718 zinc hydroxide Drugs 0.000 description 1
- 229910021511 zinc hydroxide Inorganic materials 0.000 description 1
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 1
- 229910000165 zinc phosphate Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/025—Reverse osmosis; Hyperfiltration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/04—Feed pretreatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/08—Prevention of membrane fouling or of concentration polarisation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/12—Addition of chemical agents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2321/00—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
- B01D2321/16—Use of chemical agents
- B01D2321/168—Use of other chemical agents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention
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- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
排水中のリン濃度を増加させることなく、浸透膜処理において生成する炭酸カルシウムスケールの付着を防止することができ、かつゲル化物などの微小な析出物が生成しない浸透膜用スケール防止剤及びスケール防止方法を提供する。逆浸透膜処理水系に、質量平均分子量が1.2×103〜1.8×103で、マレイン酸単位を50mol%以上含有するリン非含有マレイン酸水溶性重合物を主成分とするスケール防止剤を添加する。その際、水溶性重合物としては、例えば、ポリマレイン酸、マレイン酸とイソブチレンとのコポリマー、又はマレイン酸、エチルアクリレート及び酢酸ビニルのターポリマーなどを使用する。Without increasing the concentration of phosphorus in the wastewater, it is possible to prevent the adhesion of calcium carbonate scale generated in osmotic membrane treatment, and to prevent the formation of fine precipitates such as gelled products, and scale inhibitors for osmotic membranes and scale prevention Provide a method. A scale inhibitor containing a phosphorus-free maleic acid water-soluble polymer having a weight average molecular weight of 1.2 × 103 to 1.8 × 103 and containing 50 mol% or more of maleic acid units as a main component in a reverse osmosis membrane treated water system Add. In this case, as the water-soluble polymer, for example, polymaleic acid, a copolymer of maleic acid and isobutylene, or a terpolymer of maleic acid, ethyl acrylate and vinyl acetate is used.
Description
本発明は、逆浸透膜用スケール防止剤及びスケール防止方法に関する。より詳しくは、膜処理において発生する炭酸カルシウムスケールの付着を防止するスケール防止剤及びスケール防止方法に関する。 The present invention relates to a scale inhibitor for reverse osmosis membranes and a scale prevention method. More specifically, the present invention relates to a scale inhibitor and a scale prevention method for preventing the adhesion of calcium carbonate scale generated in film treatment.
冷却水系、ボイラ水系、膜処理又は地熱発電所の還元井においては、水と接触する伝熱面、配管或いは膜面に、スケール障害が発生する。特に、省資源・省エネルギーの観点から高濃縮運転をしたとき、また、膜の場合は回収率を高くしたときは、水に溶解している塩類が濃縮されて、難溶性の塩となってスケール化する。 In cooling water systems, boiler water systems, membrane treatment, or reduction wells of geothermal power plants, scale obstacles occur on heat transfer surfaces, piping, or membrane surfaces that come into contact with water. In particular, when highly concentrated operation is performed from the viewpoint of saving resources and energy, and when the recovery rate is increased in the case of membranes, the salt dissolved in water is concentrated to form a sparingly soluble salt. Turn into.
そして、例えば、熱交換部に生成したスケールは伝熱阻害を、配管に付着したスケールは流量低下を、膜に付着したスケールはフラックス低下を、それぞれ引き起こす。また、生成したスケールが剥離すると、系内を循環し、ポンプ、配管及び熱交換部の閉塞を引き起こし、更に、これらの閉塞に伴い、配管及び熱交換部でのスケール化が促進される。同様の現象は、地熱発電所の還元井でも起こり得る。 For example, the scale generated in the heat exchange section causes heat transfer inhibition, the scale attached to the pipe causes a decrease in flow rate, and the scale attached to the film causes a decrease in flux. Further, if the generated scale is peeled off, it circulates in the system and causes the pump, the piping and the heat exchanging section to be blocked. Further, along with the blockage, the scaling in the pipe and the heat exchanging section is promoted. A similar phenomenon can occur in the reduction well of a geothermal power plant.
これらの水系において生成するスケール種としては、炭酸カルシウム、硫酸カルシウム、亜硫酸カルシウム、リン酸カルシウム、ケイ酸カルシウム、ケイ酸マグネシウム、水酸化マグネシウム、リン酸亜鉛、水酸化亜鉛及び塩基性炭酸亜鉛などがある。 Examples of scale species generated in these aqueous systems include calcium carbonate, calcium sulfate, calcium sulfite, calcium phosphate, calcium silicate, magnesium silicate, magnesium hydroxide, zinc phosphate, zinc hydroxide, and basic zinc carbonate.
また、一般に、カルシウム系スケールに対しては、ヘキサメタリン酸ソーダやトリポリリン酸ソーダなどの無機ポリリン酸類、ヒドロキシエチリデンジホスホン酸やホスホノブタントリカルボン酸などのホスホン酸類、マレイン酸、アクリル酸及びイタコン酸などのカルボキシル基含有素材に、必要に応じてビニルスルホン酸、アリルスルホン酸及び3−アリロキシ−2−ヒドロキシプロパンスルホン酸などのスルホン酸基を有するビニルモノマーや、アクリルアミドなどのノニオン性ビニルモノマーを、対象水質に応じて組み合わせたコポリマーが、スケール防止剤として使用されている。 In general, for calcium-based scales, inorganic polyphosphoric acids such as sodium hexametaphosphate and sodium tripolyphosphate, phosphonic acids such as hydroxyethylidene diphosphonic acid and phosphonobutanetricarboxylic acid, maleic acid, acrylic acid and itaconic acid If necessary, vinyl monomers having sulfonic acid groups such as vinyl sulfonic acid, allyl sulfonic acid and 3-allyloxy-2-hydroxypropane sulfonic acid, and nonionic vinyl monomers such as acrylamide are included Copolymers combined according to water quality are used as scale inhibitors.
一方、逆浸透膜(Reverse Osmosis Membrane:RO膜)処理において生成するスケール種としては、炭酸カルシウム、硫酸カルシウム、硫酸バリウム、硫酸ストロンチウム、リン酸カルシウム及び水酸化マグネシウムなどがある。また、そのスケール防止剤としては、一般に、分子量が比較的小さく、スケール防止効果が高いことから、ヘキサメタリン酸ソーダやトリポリリン酸ソーダなどの無機ポリリン酸類、アミノメチルホスホン酸、ヒドロキシエチリデンジホスホン酸やホスホノブタントリカルボン酸などのホスホン酸類といったリンを含む素材が使用されている。 On the other hand, examples of the scale species generated in the reverse osmosis membrane (RO membrane) treatment include calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, calcium phosphate, and magnesium hydroxide. In addition, the scale inhibitor generally has a relatively low molecular weight and a high scale prevention effect. Therefore, inorganic polyphosphates such as sodium hexametaphosphate and sodium tripolyphosphate, aminomethylphosphonic acid, hydroxyethylidene diphosphonic acid and phosphonobu Materials containing phosphorus such as phosphonic acids such as tantricarboxylic acid are used.
しかしながら、近年、排水中のリン濃度が規制されたことに伴い、リンを含まないスケール防止剤が望まれている。そこで、従来、リンを含有しない炭酸カルシウムスケール防止剤が検討されている(例えば、特許文献1〜7参照。)。例えば、特許文献1に記載の方法では、スケール防止剤として、マレイン酸とアリルスルホン酸の共重合体を使用している。
However, in recent years, with the regulation of phosphorus concentration in wastewater, scale inhibitors that do not contain phosphorus are desired. Thus, conventionally, calcium carbonate scale inhibitors that do not contain phosphorus have been studied (for example, see
また、特許文献2に記載の方法では、スケール防止剤に、不飽和カルボン酸と不飽和スルホン酸から製造される共重合体と、不飽和カルボン酸とポリアルキレンオキシド側鎖を有する不飽和化合物から製造される共重合体を、組み合わせて使用している。更に、特許文献3に記載の方法では、スケール防止剤として、エチレン性不飽和二塩基カルボン酸と、第四級ジアルキルジアリルアンモニウム単量体との重合体を使用している。 In addition, in the method described in Patent Document 2, the scale inhibitor includes a copolymer produced from an unsaturated carboxylic acid and an unsaturated sulfonic acid, and an unsaturated compound having an unsaturated carboxylic acid and a polyalkylene oxide side chain. Copolymers to be produced are used in combination. Furthermore, in the method described in Patent Document 3, a polymer of an ethylenically unsaturated dibasic carboxylic acid and a quaternary dialkyl diallylammonium monomer is used as a scale inhibitor.
一方、特許文献4に記載の処理方法では、マレイン酸とエチレンアクリレートとスチレンの三元共重合体で、質量平均分子量が600〜10000のものを、スケール防止剤として使用している。また、特許文献5に記載の水系処理用組成物では、質量平均分子量が400〜800のポリマレイン酸と、分子量が800〜9500のアクリル系コポリマーとを、組み合わせて使用している。 On the other hand, in the treatment method described in Patent Document 4, a terpolymer of maleic acid, ethylene acrylate, and styrene having a mass average molecular weight of 600 to 10,000 is used as a scale inhibitor. In the aqueous treatment composition described in Patent Document 5, a polymaleic acid having a mass average molecular weight of 400 to 800 and an acrylic copolymer having a molecular weight of 800 to 9500 are used in combination.
更に、特許文献6には、特定のカルボキシル基含有水溶性共重合体を使用したスケール防止剤が提案されている。更にまた、特許文献7には、マレイン酸、無水マレイン酸、フマル酸及びイタコン酸から選択される少なくとも1種のモノマーと、その他の水溶性モノマーを水溶液重合して得た数平均分子量が400〜1000の共重合体を含有するスケール防止剤が提案されている。 Furthermore, Patent Document 6 proposes a scale inhibitor using a specific carboxyl group-containing water-soluble copolymer. Furthermore, Patent Document 7 discloses that the number average molecular weight obtained by aqueous polymerization of at least one monomer selected from maleic acid, maleic anhydride, fumaric acid and itaconic acid and other water-soluble monomers is 400 to 400. Scale inhibitors containing 1000 copolymers have been proposed.
しかしながら、前述した従来の技術には、以下に示す問題点がある。即ち、特許文献1〜7に記載されているような従来のスケール防止剤は、冷却水や蒸発濃縮など様々な系において、比較的スケール防止効果の高い素材として報告されているが、RO膜処理用として適しているとは言い難い。
However, the conventional techniques described above have the following problems. That is, conventional scale inhibitors as described in
例えば、冷却水、蒸発濃縮及びボイラなどにおいて生成するスケールは、熱交換機などの表面に一定の厚さとなって付着することにより、伝熱阻害を起こしたり、機器の安定化に影響したりする。その一方で、冷却水系などにおいては、表面に付着したスケールが防食被膜として作用するため、多少のスケール生成は許容される。このため、冷却水系などのスケール防止剤には、生成したスケール成長を抑制する能力が求められ、ある一定の析出抑制効果や耐ゲル化能を有する素材であれば、適用することが可能である。更に、冷却水系などでは、スケール防止剤として適用可能な物性(分子量や組成など)範囲も広い。 For example, scales generated in cooling water, evaporative concentration, boilers, etc. adhere to a surface of a heat exchanger or the like with a certain thickness, thereby causing heat transfer inhibition or affecting the stabilization of equipment. On the other hand, in a cooling water system or the like, the scale attached to the surface acts as an anticorrosion coating, and therefore some scale generation is allowed. For this reason, a scale inhibitor such as a cooling water system is required to have the ability to suppress the generated scale growth, and can be applied as long as it has a certain precipitation suppressing effect and gelation resistance. . Further, in a cooling water system or the like, the range of physical properties (molecular weight, composition, etc.) applicable as a scale inhibitor is wide.
これに対して、RO膜処理は、通水流路が小さく、スケール及び共存するイオンとスケール防止剤のゲル化物などの微小な析出物が生成すると、膜面が閉塞し、膜処理性能に影響する。このため、RO膜処理用のスケール防止剤には、微小な析出物を生成させないことが求められ、冷却水や蒸発濃縮などにおいて適用可能な素材であっても、更に、限られた物性条件を有する必要がある。 On the other hand, RO membrane treatment has a small water flow path, and when fine precipitates such as scales and coexisting ions and scale inhibitor gels are formed, the membrane surface is clogged, affecting membrane treatment performance. . For this reason, the scale inhibitor for RO membrane treatment is required not to generate fine precipitates, and even if it is a material that can be applied in cooling water, evaporative concentration, etc., further limited physical property conditions are required. It is necessary to have.
更に、RO膜処理は、冷却水系などに比べて、スケールを防止すべき箇所の温度が低く、水の滞留時間も短く、一般にスケール防止剤の添加濃度も低い。具体的には、スケールを防止すべき箇所の温度は、RO膜処理が10〜40℃程度であるのに対し、冷却水系などでは50〜90℃である。また、水の滞留時間は、RO膜処理が15分程度であるのに対し、冷却水系などでは20〜100時間程度である。更に、スケール防止剤の添加濃度は、RO膜処理が1〜10mg/L程度であるのに対して、冷却水系などでは5〜50mg/L程度である。 Furthermore, the RO membrane treatment has a lower temperature at a location where scale should be prevented, a shorter water residence time, and generally a lower concentration of the scale inhibitor compared to a cooling water system or the like. Specifically, the temperature at the place where scale should be prevented is about 10 to 40 ° C. for RO membrane treatment, whereas it is 50 to 90 ° C. for a cooling water system or the like. Moreover, the residence time of water is about 20 to 100 hours in the cooling water system or the like while the RO membrane treatment is about 15 minutes. Furthermore, the addition concentration of the scale inhibitor is about 1 to 10 mg / L for RO membrane treatment, whereas it is about 5 to 50 mg / L for a cooling water system or the like.
このように、RO膜処理用スケール防止剤は、冷却水系などの他の系に用いられるスケール防止剤と、処理条件や求められる特性が異なるため、冷却水系などのスケール防止剤を、RO膜処理に用いても、同様の効果は得られない。 Thus, since the scale inhibitor for RO membrane treatment is different from the scale inhibitor used in other systems such as cooling water system, the processing conditions and required characteristics are different, the scale inhibitor such as cooling water system is treated with RO membrane treatment. Even if it is used, the same effect cannot be obtained.
そこで、本発明は、排水中のリン濃度を増加させることなく、浸透膜処理において生成する炭酸カルシウムスケールの析出を抑制することができ、かつゲル化物などの微小な析出物が生成しない浸透膜用スケール防止剤及びスケール防止方法を提供することを主目的とする。 Therefore, the present invention is for an osmotic membrane that can suppress the precipitation of calcium carbonate scale generated in the osmotic membrane treatment without increasing the phosphorus concentration in the waste water, and does not produce a fine precipitate such as a gelled product. The main object is to provide a scale inhibitor and a scale prevention method.
本発明に係る逆浸透膜用スケール防止剤は、逆浸透膜処理において炭酸カルシウムスケールの析出を抑制するスケール防止剤であり、主成分が、質量平均分子量が1.2×103〜1.8×103で、マレイン酸単位が50mol%以上のリン非含有マレイン酸水溶性重合物のものである。
本発明においては、リン非含有マレイン酸水溶性重合物を主成分としているため、排水中のリン濃度を増加させることがない。また、主成分の水溶性重合物は、質量平均分子量が1.2×103〜1.8×103であり、かつ、マレイン酸単位を50mol%以上含有しているため、ゲル化物などの微小な析出物を生成しにくい。
なお、本発明における「質量平均分子量」は、ポリアクリル酸ナトリウムを標準物質として用い、ゲル浸透クロマトグラフィにより測定した値である。
このスケール防止剤では、前記水溶性重合物のマレイン酸単位を60mol%以上としてもよい。
また、水溶性重合物として、例えば、ポリマレイン酸、マレイン酸とイソブチレンとのコポリマー、並びにマレイン酸、エチルアクリレート及び酢酸ビニルのターポリマーなどを使用することができる。The scale inhibitor for reverse osmosis membrane according to the present invention is a scale inhibitor that suppresses the precipitation of calcium carbonate scale in reverse osmosis membrane treatment, and the main component has a mass average molecular weight of 1.2 × 10 3 to 1.8. It is × 10 3 and is a phosphorus-free maleic acid water-soluble polymer having a maleic acid unit of 50 mol% or more.
In the present invention, since the phosphorus-free maleic acid water-soluble polymer is a main component, the phosphorus concentration in the waste water is not increased. The main component water-soluble polymer has a mass average molecular weight of 1.2 × 10 3 to 1.8 × 10 3 and contains 50 mol% or more of maleic acid units. It is difficult to produce fine precipitates.
The “mass average molecular weight” in the present invention is a value measured by gel permeation chromatography using sodium polyacrylate as a standard substance.
In this scale inhibitor, the maleic acid unit of the water-soluble polymer may be 60 mol% or more.
Further, as the water-soluble polymer, for example, polymaleic acid, a copolymer of maleic acid and isobutylene, and a terpolymer of maleic acid, ethyl acrylate and vinyl acetate can be used.
本発明に係る逆浸透膜のスケール防止方法は、質量平均分子量が1.2×103〜1.8×103で、マレイン酸単位が50mol%以上のリン非含有マレイン酸水溶性重合物を主成分とするスケール防止剤を、逆浸透膜処理水系に添加する。
本発明においては、分子量が特定の範囲内にあり、マレイン酸単位が50mol%以上のリン非含有のマレイン酸水溶性重合物を主成分とするスケール防止剤を使用しているため、排水中のリン濃度が増加せず、ゲル化物などの微小な析出物も生成しない。
このスケール防止方法では、前記スケール防止剤の主成分である水溶性重合物を、マレイン酸単位が60mol%以上のものにしてもよい。According to the reverse osmosis membrane scale prevention method of the present invention, a phosphorus-free maleic acid water-soluble polymer having a weight average molecular weight of 1.2 × 10 3 to 1.8 × 10 3 and having a maleic acid unit of 50 mol% or more is used. A scale inhibitor as a main component is added to the reverse osmosis membrane treated water system.
In the present invention, a scale inhibitor mainly composed of a phosphorus-free maleic acid water-soluble polymer having a molecular weight within a specific range and having a maleic acid unit of 50 mol% or more is used. The phosphorus concentration does not increase, and fine precipitates such as gelled products are not generated.
In this scale prevention method, the water-soluble polymer that is the main component of the scale inhibitor may have a maleic acid unit of 60 mol% or more.
本発明によれば、スケール防止剤の主成分を、分子量及びマレイン酸含有量が特定の範囲内にあるリン非含有マレイン酸水溶性重合物としているため、排水中のリン濃度を増加させることなく、浸透膜処理において生成する炭酸カルシウムスケールの析出を抑制することができ、更にゲル化物などの微小な析出物も生成しない。 According to the present invention, since the main component of the scale inhibitor is a phosphorus-free maleic acid water-soluble polymer having a molecular weight and a maleic acid content within a specific range, without increasing the phosphorus concentration in the wastewater. Further, precipitation of calcium carbonate scale generated in the osmotic membrane treatment can be suppressed, and further, fine precipitates such as gelled products are not generated.
以下、本発明を実施するための形態について、詳細に説明する。なお、本発明は、以下に説明する実施形態に限定されるものではない。 Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.
(第1の実施形態)
先ず、本発明の第1の実施形態に係るスケール防止剤について説明する。本実施形態のスケール防止剤は、逆浸透膜処理で発生する炭酸カルシウムスケールの析出を抑制し、RO膜などにスケールが付着することを防止するものであり、その主成分は、リン非含有のマレイン酸水溶性重合物である。ここで、「マレイン酸水溶性重合物」とは、マレイン酸の単独重合体又はマレイン酸とリンを含有しない他の単量体の共重合体で、水溶性のものである。(First embodiment)
First, the scale inhibitor according to the first embodiment of the present invention will be described. The scale inhibitor of the present embodiment suppresses the precipitation of calcium carbonate scale that occurs in the reverse osmosis membrane treatment, and prevents the scale from adhering to the RO membrane and the like. It is a maleic acid water-soluble polymer. Here, the “maleic acid water-soluble polymer” is a homopolymer of maleic acid or a copolymer of maleic acid and other monomers not containing phosphorus, which is water-soluble.
本実施形態のスケール防止剤においては、分子量が1.2×103〜1.8×103のマレイン酸水溶性重合物を使用する。なお、ここで規定する分子量は、ポリアクリル酸ナトリウムを標準物質として用い、ゲル浸透クロマトグラフィにより測定した質量平均分子量であり、以下の説明においても同様である。In the scale inhibitor of the present embodiment, a maleic acid water-soluble polymer having a molecular weight of 1.2 × 10 3 to 1.8 × 10 3 is used. The molecular weight defined here is a mass average molecular weight measured by gel permeation chromatography using sodium polyacrylate as a standard substance, and the same applies to the following description.
一般に、水溶性重合物は、分子量が大きいほどゲル化しやすくなるため、分子量を小さくすることにより、耐ゲル化能を向上させることができる。一方、分子量が小さいマレイン酸水溶性重合物を得るためには、重合開始剤や連鎖移動剤とモノマーを反応させることにより、重合を停止する必要がある。このため、マレイン酸水溶性重合物は、分子量を小さくしすぎると、カルボキシル基の数が減り、分散効果を示すアニオン基の数が少なくなるため、却ってゲル化しやすくなる。 In general, since the water-soluble polymer is easily gelled as the molecular weight increases, the gelation resistance can be improved by reducing the molecular weight. On the other hand, in order to obtain a maleic acid water-soluble polymer having a small molecular weight, it is necessary to stop the polymerization by reacting a polymerization initiator or a chain transfer agent with a monomer. For this reason, if the molecular weight of the maleic acid water-soluble polymer is too small, the number of carboxyl groups decreases, and the number of anionic groups exhibiting a dispersion effect decreases, so that gelation tends to occur.
具体的には、分子量が1.2×103未満のマレイン酸水溶性重合物は、重合物中のマレイン酸単位が少なくなるため、カチオン濃度が低い環境下であってもゲル化しやすくなる。また、マレイン酸水溶性重合物の分子量を1.2×103未満にすると、重合物中に重合開始剤や連鎖移動剤が残留するが、これもアニオン基であるカルボキシル基の数が減少する要因となる。Specifically, a maleic acid water-soluble polymer having a molecular weight of less than 1.2 × 10 3 tends to gel even in an environment where the cation concentration is low because maleic acid units in the polymer are reduced. Moreover, when the molecular weight of the maleic acid water-soluble polymer is less than 1.2 × 10 3 , a polymerization initiator and a chain transfer agent remain in the polymer, but this also reduces the number of carboxyl groups which are anionic groups. It becomes a factor.
このような理由から、数平均分子量が400〜1000の共重合体を使用する特許文献7に記載のスケール防止剤には、カチオン濃度が低い環境下であってもゲル化物などの微小な析出物が生成しやすいという問題がある。 For these reasons, the scale inhibitor described in Patent Document 7 using a copolymer having a number average molecular weight of 400 to 1000 is a fine precipitate such as a gelled substance even in an environment where the cation concentration is low. Is easy to generate.
一方、マレイン酸水溶性重合物の分子量を大きくしすぎると、1つのカチオン、特に多価カチオンに対して、重合体分子中の複数のカルボキシル基が作用し、分子鎖が曲がった状態となるため、ゲル化しやすくなる。具体的には、分子量が1.8×103を超えるマレイン酸水溶性重合物は、カチオン濃度が低い環境下でもゲル化しやすく、このような水溶性重合物を使用すると、微小な析出物が生じやすくなる。On the other hand, if the molecular weight of the maleic acid water-soluble polymer is too large, a plurality of carboxyl groups in the polymer molecule act on one cation, especially a polyvalent cation, and the molecular chain is bent. , Easily gelled. Specifically, a maleic acid water-soluble polymer having a molecular weight exceeding 1.8 × 10 3 tends to gel even in an environment where the cation concentration is low, and when such a water-soluble polymer is used, minute precipitates are formed. It tends to occur.
また、このマレイン酸水溶性重合物中のマレイン酸単位の量は、50〜100mol%である。マレイン酸単位が50mol%未満のマレイン酸水溶性重合物は、アニオン基であるカルボキシル基の数が少ないため、ゲル化しやすい。なお、マレイン酸水溶性重合物中のマレイン酸単位の量は、炭酸カルシウムの析出抑制効果向上の観点から、60mol%以上であることが好ましく、より好ましくは75mol%以上である。 The amount of maleic acid units in the maleic acid water-soluble polymer is 50 to 100 mol%. A maleic acid water-soluble polymer having a maleic acid unit of less than 50 mol% is easily gelled because of a small number of carboxyl groups which are anionic groups. The amount of maleic acid units in the maleic acid water-soluble polymer is preferably 60 mol% or more, more preferably 75 mol% or more, from the viewpoint of improving the calcium carbonate precipitation suppression effect.
本実施形態のスケール防止剤に配合されるマレイン酸水溶性重合物は、ポリマレイン酸のようなマレイン酸の単独重合体の他、マレイン酸と他の単量体の共重合体でもよい。その際、マレイン酸と共重合される単量体は、リンを含有しないノニオン性モノマーであればよく、例えば、モノエチレン性不飽和炭化水素、モノエチレン性不飽和酸のアルキルエステル、モノエチレン性不飽和酸のビニルエステル及び置換アクリルアミドなどが挙げられる。 The maleic acid water-soluble polymer blended in the scale inhibitor of the present embodiment may be a maleic acid homopolymer such as polymaleic acid or a copolymer of maleic acid and another monomer. In this case, the monomer copolymerized with maleic acid may be a nonionic monomer containing no phosphorus, such as monoethylenically unsaturated hydrocarbons, alkyl esters of monoethylenically unsaturated acids, monoethylenic monomers. Examples include vinyl esters of unsaturated acids and substituted acrylamides.
また、モノエチレン性不飽和炭化水素は、炭素数が3〜8の直鎖状(分岐を有するものも含む)又は環状のものを使用することができ、その具体例としては、イソブチレンやスチレンなどがある。モノエチレン性不飽和酸のアルキルエステルは、炭素数が1〜8のものを使用することができ、その具体例としては、メチル(メタ)アクリレート、エチル(メタ)アクリレート、イソプロピルアクリレート、N−ブチルアクリレート、2−エチルヘキシルアクリレートなどがある。 The monoethylenically unsaturated hydrocarbon may be a straight chain (including branched ones) having 3 to 8 carbon atoms or a cyclic one. Specific examples thereof include isobutylene and styrene. There is. As the alkyl ester of monoethylenically unsaturated acid, those having 1 to 8 carbon atoms can be used. Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl acrylate, N-butyl. Examples include acrylate and 2-ethylhexyl acrylate.
モノエチレン性不飽和酸のビニルエステルは、炭素数1〜8のものを使用することができ、その具体例としては、酢酸ビニルやプロピオン酸ビニルなどがある。置換アクリルアミドは、炭素数が1〜4のものを使用することができ、その具体例としては、アクリルアミド、プロピルアクリルアミド、N−イソプロピルアクリルアミド、ジメチルアクリルアミド及びジエチルアクリルアミドなどがある。 As the vinyl ester of monoethylenically unsaturated acid, one having 1 to 8 carbon atoms can be used, and specific examples thereof include vinyl acetate and vinyl propionate. As the substituted acrylamide, those having 1 to 4 carbon atoms can be used, and specific examples thereof include acrylamide, propylacrylamide, N-isopropylacrylamide, dimethylacrylamide, and diethylacrylamide.
なお、アクリル酸は、マレイン酸に比べて重合しやすいが、低分子量に制御することが難しい。一方、耐ゲル化能を向上させる方法としては、スルホン酸とコポリマー化する方法があるが、スルホン酸とコポリマー化すると、カルボキシル基の数が減少するため、逆に析出抑制能が低下する。従って、アクリル酸は、マレイン酸に比べて、析出抑制能及び耐ゲル化能の両方の性能が高い物性を見出すことが困難である。 In addition, although acrylic acid is easy to superpose | polymerize compared with maleic acid, it is difficult to control to low molecular weight. On the other hand, as a method for improving the gelation resistance, there is a method of copolymerizing with sulfonic acid. However, when copolymerized with sulfonic acid, the number of carboxyl groups decreases, and conversely, the ability to suppress precipitation decreases. Therefore, it is difficult for acrylic acid to find physical properties with high performance of both precipitation suppression ability and gelation resistance compared to maleic acid.
これに対して、マレイン酸は、アクリル酸に比べて、モノマー中のカルボキシル基の数が多く、コポリマー化しても高い析出抑制能を示す。また、マレイン酸は、アクリル酸に比べて、重合反応が遅いため、分子量を小さく制御することも可能である。 On the other hand, maleic acid has a larger number of carboxyl groups in the monomer than acrylic acid, and exhibits high ability to suppress precipitation even when copolymerized. Further, since maleic acid has a slower polymerization reaction than acrylic acid, the molecular weight can be controlled to be small.
また、前述したマレイン酸水溶性重合物の製造方法は、特に限定されるものではなく、溶液重合、懸濁重合、乳化重合及び塊状重合などを適用することができるが、マレイン酸単位を有する重合物は、トルエン又はキシレンを用いる重合方法が好適である。この重合方法の場合、開始剤には公知の過酸化物開始剤を適宜選択して使用することができる。具体的には、ジベンゾイルペルオキシド、第三ブチルペルペンゾエート、ジクミルペルオキシド、第三ブチルヒドロペルオキシド及び第三ブチルペルオキシドなどを使用することができる。 Further, the method for producing the maleic acid water-soluble polymer described above is not particularly limited, and solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, and the like can be applied, but polymerization having a maleic acid unit. The product is preferably a polymerization method using toluene or xylene. In the case of this polymerization method, a known peroxide initiator can be appropriately selected and used as the initiator. Specifically, dibenzoyl peroxide, tert-butyl perpenzoate, dicumyl peroxide, tert-butyl hydroperoxide, tert-butyl peroxide, and the like can be used.
この場合の重合形式は、回分式及び連続式いずれでもよく、例えば、100〜200℃の温度に加熱し、2〜6時間重合した後、放冷することにより、マレイン酸水溶性重合物を得ることができる。 The polymerization mode in this case may be either a batch type or a continuous type. For example, a maleic acid water-soluble polymer is obtained by heating to a temperature of 100 to 200 ° C., polymerizing for 2 to 6 hours, and then allowing to cool. be able to.
一方、水性重合の場合は、例えば、単量体水溶液又は水分散液を調整し、必要に応じてpHの調整を行い、不活性ガスにより雰囲気を置換した後、50〜100℃に加熱し、水溶性重合開始剤を添加すればよい。その際使用する水溶性重合開始剤としては、例えば、2,2’−アゾビス(2−アミジノプロパン)二塩酸塩、アゾビス−N,N’−ジメチレンイソブチルアミジン二塩酸塩及び4,4’−アゾビス(4−シアノ吉草酸)−2−ナトリウムなどのアゾ化合物、過硫酸アンモニウム、過硫酸ナトリウム、過硫酸カリウムなどの過硫酸塩、過酸化水素及び過ヨウ素酸ナトリウムなどの過酸化物を使用することができる。 On the other hand, in the case of aqueous polymerization, for example, an aqueous monomer solution or aqueous dispersion is prepared, pH is adjusted as necessary, the atmosphere is replaced with an inert gas, and then heated to 50 to 100 ° C., A water-soluble polymerization initiator may be added. Examples of the water-soluble polymerization initiator used here include 2,2′-azobis (2-amidinopropane) dihydrochloride, azobis-N, N′-dimethyleneisobutylamidine dihydrochloride, and 4,4′-. Use azo compounds such as azobis (4-cyanovaleric acid) -2-sodium, persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate, peroxides such as hydrogen peroxide and sodium periodate. Can do.
また、その場合の重合条件は、特に限定されるものではないが、例えば、2〜6時間重合した後、放冷することにより、重合体水溶液又は水分散液を得ることができる。なお、マレイン酸水溶性重合物の重合は、水性媒体中に限らず、一般的な有機溶媒中での溶液重合、懸濁重合及び乳化重合などによっても行うことができる。 In addition, the polymerization conditions in that case are not particularly limited. For example, after polymerization for 2 to 6 hours, the polymer aqueous solution or the aqueous dispersion can be obtained by cooling. The polymerization of the maleic acid water-soluble polymer is not limited to an aqueous medium, and can be performed by solution polymerization, suspension polymerization, emulsion polymerization, or the like in a general organic solvent.
本実施形態のスケール防止剤には、前述したマレイン酸水溶性重合物に加えて、本発明の目的を阻害しない範囲で、スライムコントロール剤、酵素、殺菌剤、着色剤、香料、水溶性有機溶媒及び消泡剤などが配合されていてもよい。その場合、スライムコントロール剤としては、例えば、アルキルジメチルベンジルアンモニウムクロライドなどの四級アンモニウム塩、クロルメチルトリチアゾリン、クロルメチルイソチアゾリン、メチルイソチアゾリン、エチルアミノイソプロピルアミノメチルチアトリアジン、次亜塩素酸、次亜臭素酸、及び次亜塩素酸とスルファミン酸の混合物などを使用することができる。 In addition to the above-described maleic acid water-soluble polymer, the scale inhibitor of the present embodiment includes a slime control agent, an enzyme, a disinfectant, a colorant, a fragrance, and a water-soluble organic solvent as long as the object of the present invention is not impaired. And an antifoamer etc. may be mix | blended. In this case, examples of the slime control agent include quaternary ammonium salts such as alkyldimethylbenzylammonium chloride, chloromethyltrithiazoline, chloromethylisothiazoline, methylisothiazoline, ethylaminoisopropylaminomethylthiatriazine, hypochlorous acid, hypochlorous acid, and hypochlorous acid. Bromic acid, a mixture of hypochlorous acid and sulfamic acid, and the like can be used.
以上詳述したように、本実施形態のスケール防止剤は、リン非含有のマレイン酸水溶性重合物を主成分としているため、排水中のリン濃度を増加させることなく、炭酸カルシウムスケールの析出を抑制することができる。また、この水溶性重合物は、分子量が1.2×103〜1.8×103であるため、ゲル化物などの微小な析出物を生成しにくい。更に、本実施形態のスケール防止剤は、少量の添加で、安定してスケールの析出を抑制することができる。このため、本実施形態のスケール防止剤は、逆浸透膜処理に好適である。なお、本実施形態のスケール防止剤を適用する場合の水質条件及び水系の運転条件には、特に制限はない。As described above in detail, the scale inhibitor of the present embodiment is mainly composed of a maleic acid water-soluble polymer that does not contain phosphorus, so that the calcium carbonate scale is deposited without increasing the phosphorus concentration in the waste water. Can be suppressed. Moreover, since this water-soluble polymer has a molecular weight of 1.2 × 10 3 to 1.8 × 10 3, it is difficult to produce fine precipitates such as gelled products. Furthermore, the scale inhibitor of this embodiment can stably suppress the precipitation of scale with a small amount of addition. For this reason, the scale inhibitor of this embodiment is suitable for reverse osmosis membrane treatment. In addition, there is no restriction | limiting in particular in the water quality condition in the case of applying the scale inhibitor of this embodiment, and the operating condition of water system.
(第2の実施形態)
次に、本発明の第2の実施形態に係るスケール防止方法について説明する。本実施形態のスケール防止方法は、前述した第1の実施形態のスケール防止剤を使用して、逆浸透膜処理において炭酸カルシウムスケールの析出を抑制する方法である。即ち、本実施形態のスケール防止方法は、分子量が1.2×103〜1.8×103で、マレイン酸単位が50mol%以上のリン非含有マレイン酸水溶性重合物を主成分とするスケール防止剤を、逆浸透膜処理水系に添加する。(Second Embodiment)
Next, a scale prevention method according to the second embodiment of the present invention will be described. The scale prevention method of the present embodiment is a method for suppressing the precipitation of calcium carbonate scale in the reverse osmosis membrane treatment using the scale inhibitor of the first embodiment described above. That is, the scale prevention method of this embodiment is mainly composed of a phosphorus-free maleic acid water-soluble polymer having a molecular weight of 1.2 × 10 3 to 1.8 × 10 3 and maleic acid units of 50 mol% or more. A scale inhibitor is added to the reverse osmosis membrane treated water system.
本実施形態のスケール防止方法においては、スケール防止剤の添加方法は、特に限定されるものではなく、スケールの付着を防止したい場所やその直前などで添加すればよい。また、その添加量も、特に限定されるものではなく、水系の水質に応じて適宜選択することができるが、マレイン酸水溶性重合物の濃度が0.01〜100mg/Lとなるように添加することが好ましく、特に、膜面の閉塞防止の観点から、0.1〜10mg/Lとなるように添加することがより好ましい。 In the scale prevention method of the present embodiment, the addition method of the scale inhibitor is not particularly limited, and may be added at a place where it is desired to prevent the scale from being attached or immediately before that. Further, the amount of addition is not particularly limited and can be appropriately selected according to the water quality of the aqueous system, but added so that the concentration of the maleic acid water-soluble polymer is 0.01 to 100 mg / L. In particular, from the viewpoint of prevention of blockage of the membrane surface, it is more preferable to add so as to be 0.1 to 10 mg / L.
また、本実施形態のスケール防止方法は、前述した第1の実施形態のスケール防止剤と、他のスケール防止剤とを併用することもできる。併用するスケール防止剤としては、例えば、ポリアクリル酸、マレイン酸とアクリル酸の共重合体、マレイン酸とスルホン酸の共重合体、アクリル酸とスルホン酸の共重合体、アクリル酸とノニオン基含有モノマーのコポリマー、アクリル酸とスルホン酸とノニオン基含有モノマーのターポリマーなどが挙げられる。 Moreover, the scale prevention method of this embodiment can also use together the scale inhibitor of 1st Embodiment mentioned above, and another scale inhibitor. Examples of the scale inhibitor used in combination include polyacrylic acid, a copolymer of maleic acid and acrylic acid, a copolymer of maleic acid and sulfonic acid, a copolymer of acrylic acid and sulfonic acid, and an acrylic acid and nonionic group Examples thereof include copolymers of monomers, terpolymers of acrylic acid, sulfonic acid, and nonionic group-containing monomers.
前述した共重合体などを構成するスルホン酸としては、例えば、ビニルスルホン酸、アリルスルホン酸、スチレンスルホン酸、イソプレンスルホン酸、3−アリロキシ−2−ヒドロキシプロパンスルホン酸、2−アクリルアミド−2―メチルプロパンスルホン酸、2−メタクリルアミド−2−メチルプロパンスルホン酸、メタクリル酸−4−スルホブチル、アリルオキシベンゼンスルホン酸及びメタリルオキシベンゼンスルホン酸又はこれらの金属塩などが挙げられる。 Examples of the sulfonic acid constituting the copolymer described above include, for example, vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, isoprene sulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, 2-acrylamido-2-methyl. Examples thereof include propanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, -4-sulfobutyl methacrylate, allyloxybenzenesulfonic acid, methallyloxybenzenesulfonic acid, and metal salts thereof.
また、ノニオン基含有モノマーとしては、例えば、炭素数1〜5のアルキルアミド、ヒドロキシエチルメタクリレート、付加モル数が1〜30の(ポリ)エチレン/プロピレンオキサイドのモノ(メタ)アクリレート及び付加モル数が1〜30のモノビニルエーテルエチレン/プロピレンオキサイドなどが挙げられる。 Examples of the nonionic group-containing monomer include alkylamides having 1 to 5 carbon atoms, hydroxyethyl methacrylate, (poly) ethylene / propylene oxide mono (meth) acrylates having 1 to 30 addition moles, and addition moles. Examples thereof include 1-30 monovinyl ether ethylene / propylene oxide.
このように、本実施形態のスケール防止方法では、分子量が特定の範囲内にあるリン非含有のマレイン酸水溶性重合物を主成分とするスケール防止剤を使用しているため、排水中のリン濃度を増加させることなく、浸透膜処理において生成する炭酸カルシウムスケールの析出を抑制することができ、更にゲル化物などの微小な析出物も生成しない。また、本実施形態のスケール防止方法は、水系にスケール防止剤を少量添加するだけで、安定してスケールの析出を抑制することが可能となる。 Thus, in the scale prevention method of this embodiment, since the scale inhibitor mainly composed of a phosphorus-free maleic acid-soluble water-soluble polymer having a molecular weight within a specific range is used, phosphorus in wastewater is used. Without increasing the concentration, precipitation of calcium carbonate scale generated in the osmotic membrane treatment can be suppressed, and fine precipitates such as gelled products are not generated. Moreover, the scale prevention method of this embodiment can suppress the precipitation of scale stably only by adding a small amount of a scale inhibitor to the aqueous system.
なお、本実施形態のスケール防止方法は、適用する水系の水質条件及び運転条件は、特に限定されない。また、本実施形態のスケール防止方法における上記以外の構成及び効果は、前述した第1の実施形態と同様である。 In addition, the water quality conditions and operation conditions of the water system to which the scale prevention method of this embodiment is applied are not particularly limited. In addition, the configuration and effects other than those described above in the scale prevention method of the present embodiment are the same as those of the first embodiment described above.
以下、本発明の実施例及び比較例を挙げて、本発明の効果について具体的に説明する。本実施例においては、以下に示す方法で、本発明の範囲内の実施例1〜7のスケール防止剤及び本発明の範囲から外れる比較例1〜9のスケール防止剤について、その性能を評価した。 Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention. In this example, the performance of the scale inhibitors of Examples 1 to 7 within the scope of the present invention and the scale inhibitors of Comparative Examples 1 to 9 deviating from the scope of the present invention was evaluated by the method described below. .
<平膜試験>
先ず、膜の初期性能を測定するため、500mg/LのNaCl水溶液を、ポリアミド逆浸透膜(日東電工社製 ES20)に、操作圧を0.75MPa、回収率を50%として通水し、フラックス(Flux)を所定時間測定した。<Flat membrane test>
First, in order to measure the initial performance of the membrane, a 500 mg / L NaCl aqueous solution was passed through a polyamide reverse osmosis membrane (ES20 manufactured by Nitto Denko Corporation) at an operating pressure of 0.75 MPa and a recovery rate of 50%. (Flux) was measured for a predetermined time.
次に、塩化カルシウム:250mgCaCO3/L、実施例1〜7及び比較例1〜9のスケール防止剤(重合物):1mg/L、炭酸水素ナトリウム:250mgCaCO3/Lを含有する水溶液を調整し、更に、少量の水酸化ナトリウム水溶液又は硫酸水溶液でpHを8.5に調製して試験溶液とした。そして、各試験溶液を、ポリアミド逆浸透膜(日東電工社製 ES20)に、操作圧を0.75MPa、回収率を50%として通水し、フラックス(Flux)を所定時間測定した。Next, an aqueous solution containing calcium chloride: 250 mg CaCO 3 / L, Examples 1 to 7 and Comparative Examples 1 to 9 scale inhibitors (polymers): 1 mg / L, sodium bicarbonate: 250 mg CaCO 3 / L was prepared. Furthermore, the pH was adjusted to 8.5 with a small amount of aqueous sodium hydroxide or sulfuric acid solution to prepare a test solution. Each test solution was passed through a polyamide reverse osmosis membrane (ES20 manufactured by Nitto Denko Corporation) at an operating pressure of 0.75 MPa and a recovery rate of 50%, and flux was measured for a predetermined time.
その結果を、図1及び図2に示す。なお、図1及び図2は、500mg/LのNaCl水溶液におけるフラックスを1とし、試験溶液で測定したフラックスとの比(フラックス比)の経時変化を示す図である。また、図1及び図2に示すブランク(Blank)は、薬品未添加のときのフラックス比である。 The results are shown in FIGS. FIGS. 1 and 2 are graphs showing changes with time in the ratio (flux ratio) to the flux measured with the test solution, where the flux in a 500 mg / L NaCl aqueous solution is 1. FIG. Moreover, the blank (Blank) shown in FIG.1 and FIG.2 is a flux ratio when a chemical | medical agent is not added.
<机上試験>
(1)析出抑制試験
500mlのコニカルビーカーに、超純水:500mlを入れ、塩化カルシウム:500mgCaCO3/L、スケール防止剤:2mg/L、炭酸水素ナトリウム:500mgCaCO3/Lを含有する水溶液を調整し、更に、水酸化ナトリウム水溶液又は硫酸水溶液でpHを8.5に調製して試験溶液とした。そして、ビーカーを密栓し、30℃の恒温槽中で、各試験溶液を3時間撹拌した。その後、孔径0.1μmの濾紙を用いて、EDTA法により、濾液のカルシウム硬度を定量した。<Desktop test>
(1) Precipitation suppression test Into a 500 ml conical beaker, 500 ml of ultrapure water is added, and an aqueous solution containing calcium chloride: 500 mg CaCO 3 / L, scale inhibitor: 2 mg / L, sodium bicarbonate: 500 mg CaCO 3 / L is prepared. Further, the pH was adjusted to 8.5 with an aqueous sodium hydroxide solution or an aqueous sulfuric acid solution to obtain a test solution. Then, the beaker was sealed and each test solution was stirred for 3 hours in a thermostatic bath at 30 ° C. Thereafter, the calcium hardness of the filtrate was quantified by an EDTA method using a filter paper having a pore diameter of 0.1 μm.
(2)ゲル化性能試験
500mlのコニカルビーカーに、超純水:500mlを入れ、これにホウ酸塩緩衝液(Buffer)、スケール防止剤及び塩化カルシウムを加えた後、水酸化ナトリウム水溶液又は硫酸水溶液でpHを8.5に調製して試験溶液とした。そして、ビーカーを密栓し、90℃の恒温槽中で、1時間静置した。その後、50mmのセルを使用して、波長380nmの吸光度を測定した。そして、カルシウム硬度を変化させて、急激に吸光度が大きくなるカルシウム硬度を、ゲル化点とした。(2) Gelation performance test Into a 500 ml conical beaker, 500 ml of ultrapure water: 500 ml is added, and after adding borate buffer (Buffer), scale inhibitor and calcium chloride, sodium hydroxide aqueous solution or sulfuric acid aqueous solution The pH was adjusted to 8.5 to prepare a test solution. Then, the beaker was sealed and left in a constant temperature bath at 90 ° C. for 1 hour. Thereafter, the absorbance at a wavelength of 380 nm was measured using a 50 mm cell. And the calcium hardness which changes a calcium hardness and a light absorbency increases rapidly was made into the gel point.
これらの机上試験の結果を、下記表1及び表2にまとめて示す。なお、下記表1及び表2には、実施例1〜7及び比較例1〜9のスケール防止剤の詳細も併せて示す。また、下記表1及び表2に示す各モノマーは、MA:マレイン酸、IB:イソブチレン、VA:酢酸ビニル、EA:エチルアクリレート、AA:アクリル酸、SA:スルホン酸である。 The results of these desktop tests are summarized in Table 1 and Table 2 below. In addition, in the following Table 1 and Table 2, the detail of the scale inhibitor of Examples 1-7 and Comparative Examples 1-9 is also shown collectively. The monomers shown in Tables 1 and 2 below are MA: maleic acid, IB: isobutylene, VA: vinyl acetate, EA: ethyl acrylate, AA: acrylic acid, and SA: sulfonic acid.
図1に示すように、薬品未添加のBlankでは、フレックスの低下が見られたが、実施例1〜7のスケール防止剤を添加したものでは、いずれもフレックスの低下は見られなかった。これにより、実施例1〜7のスケール防止剤を添加した系では、スケールの析出が抑制され、安定した膜処理が可能であることがわかった。また、上記表1に示すように、実施例1〜7のスケール防止剤は、机上試験においても、炭酸カルシウム析出抑制効果が高く、耐ゲル化能にも優れていた。 As shown in FIG. 1, in the blank to which no chemical was added, a decrease in flex was observed, but in the case where the scale inhibitors of Examples 1 to 7 were added, no decrease in flex was observed. Thereby, in the system which added the scale inhibitor of Examples 1-7, precipitation of a scale was suppressed and it turned out that the stable film | membrane process is possible. Moreover, as shown in the said Table 1, the scale inhibitor of Examples 1-7 was high in the carbonate carbonate precipitation inhibitory effect also in the desk test, and was excellent also in the gelation ability.
これに対して、図2に示すように、比較例1〜9のスケール防止剤を使用した系では、フラックスの低下が見られた。その低下速度を比較すると、実施例1〜7<比較例6<比較例7<比較例5,8,9<比較例1,3,Blank<比較例2,4の順であった。また、上記表2に示すように、机上試験において、比較例6のスケール防止剤は、実施例1〜7のスケール防止剤には劣るが、比較例1〜5,7〜9のスケール防止剤に比べて、炭酸カルシウム析出抑制効果及び耐ゲル化能が高かった。 On the other hand, as shown in FIG. 2, in the system using the scale inhibitors of Comparative Examples 1 to 9, a decrease in flux was observed. The rate of decrease was in the order of Examples 1 to 7 <Comparative Example 6 <Comparative Example 7 <Comparative Examples 5, 8, 9 <Comparative Examples 1, 3 and Blank <Comparative Examples 2 and 4. Moreover, as shown in the said Table 2, in the desk test, although the scale inhibitor of the comparative example 6 is inferior to the scale inhibitor of Examples 1-7, the scale inhibitor of Comparative Examples 1-5, 7-9 In comparison with, the calcium carbonate precipitation inhibitory effect and gelation resistance were high.
比較例1〜4,7のスケール防止剤は、析出抑制試験において濾液のカルシウム濃度を維持できていたが、耐ゲル化能が低いため、ゲル化物が生成して、フラックスが低下したものと考えられる。また、比較例5,8,9のスケール防止剤は、耐ゲル化性能は優れていたが、析出抑制試験において、濾液のカルシウム濃度を維持できなかったことから、炭酸カルシウムが析出してフラックスが低下したものと考えられる。 Although the scale inhibitors of Comparative Examples 1 to 4 and 7 were able to maintain the calcium concentration of the filtrate in the precipitation suppression test, it was considered that the gelation product was generated and the flux was reduced because the gelation resistance was low. It is done. In addition, the scale inhibitors of Comparative Examples 5, 8, and 9 were excellent in gelation resistance performance, but in the precipitation suppression test, the calcium concentration of the filtrate could not be maintained, so that calcium carbonate precipitated and the flux increased. It is thought that it decreased.
ここで、マレイン酸とイソブチレンのコポリマーを使用した実施例2のスケール防止剤と、比較例5のスケール防止剤とを比較すると、比較例5のスケール防止剤はマレイン酸単位が50mol%未満であり、実施例2のスケール防止剤に比べて、炭酸カルシウム析出抑制能を有するカルボキシル基の数が少ない。このため、比較例5のスケール防止剤は、実施例2のスケール防止剤とゲル化点が同等であっても、炭酸カルシウムの析出を十分に抑制できず、膜を安定に運転できなくなったものと考えられる。 Here, when the scale inhibitor of Example 2 using a copolymer of maleic acid and isobutylene was compared with the scale inhibitor of Comparative Example 5, the scale inhibitor of Comparative Example 5 had less than 50 mol% of maleic acid units. Compared to the scale inhibitor of Example 2, the number of carboxyl groups having calcium carbonate precipitation inhibiting ability is small. For this reason, even if the scale inhibitor of Comparative Example 5 has the same gel point as the scale inhibitor of Example 2, precipitation of calcium carbonate could not be sufficiently suppressed and the membrane could not be operated stably. it is conceivable that.
即ち、ポリマレイン酸を使用した実施例1のスケール防止剤、マレイン酸とイソブチレンのコポリマーを使用した実施例2、4、5及び7のスケール防止剤、マレイン酸と、エチルアクリレートと、酢酸ビニルのターポリマーを使用した実施例3,6のスケール防止剤は、炭酸カルシウムの析出を抑制できていた。また、これらの重合物(ポリマー)は、分子量が1.2×103〜1.8×103で、ゲル化点が高いため、比較例1〜4のスケール防止剤に比べてゲル化物を生成しにくく、膜を安定に運転できることが確認された。更に、実施例1〜7のスケール防止剤は、リン非含有マレイン酸水溶性重合物のマレイン酸単位が50mol%以上であるため、炭酸カルシウム析出抑制能に優れていた。That is, the scale inhibitor of Example 1 using polymaleic acid, the scale inhibitor of Examples 2, 4, 5 and 7 using a copolymer of maleic acid and isobutylene, maleic acid, ethyl acrylate and vinyl acetate. The scale inhibitor of Examples 3 and 6 using a polymer was able to suppress the precipitation of calcium carbonate. In addition, these polymers (polymers) have a molecular weight of 1.2 × 10 3 to 1.8 × 10 3 and a high gel point, so that the gelled product is smaller than the scale inhibitors of Comparative Examples 1 to 4. It was confirmed that it was difficult to produce and the membrane could be operated stably. Furthermore, since the scale inhibitors of Examples 1 to 7 contained 50 mol% or more of the maleic acid unit of the phosphorus-free maleic acid water-soluble polymer, they were excellent in calcium carbonate precipitation inhibiting ability.
以上の結果から、本発明によれば、排水中のリン濃度を増加させることなく、高濃度で添加しなくても、浸透膜処理において生成する炭酸カルシウムスケールの析出を抑制することができ、かつゲル化物などの微小な析出物が生成しない浸透膜用スケール防止剤を実現できることが確認された。 From the above results, according to the present invention, without increasing the phosphorus concentration in the wastewater, it is possible to suppress the precipitation of calcium carbonate scale generated in the osmotic membrane treatment without adding at a high concentration, and It was confirmed that a scale inhibitor for osmotic membranes in which fine precipitates such as gelled products are not generated can be realized.
Claims (7)
主成分が、質量平均分子量が1.2×103〜1.8×103で、マレイン酸単位が50mol%以上のリン非含有マレイン酸水溶性重合物である逆浸透膜用スケール防止剤。A scale inhibitor that suppresses the precipitation of calcium carbonate scale in reverse osmosis membrane treatment,
A scale inhibitor for reverse osmosis membranes, wherein the main component is a phosphorus-free maleic acid water-soluble polymer having a mass average molecular weight of 1.2 × 10 3 to 1.8 × 10 3 and maleic acid units of 50 mol% or more.
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