JPS61209095A - Water treatment method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the use of partial esters of polymaleic acid for treating aqueous systems.

BACKGROUND OF THE INVENTION Natural waters and the majority of aqueous systems generally contain dissolved salts of metals such as calcium, magnesium, barium and strontium. When water or an aqueous system is heated, dissolved salts turn into insoluble salts and can be deposited as scale on heat transfer surfaces that come into contact with the water or aqueous system. Insoluble salts may also precipitate when water or aqueous systems are amended without being heated.

Salt precipitation and scale deposition are problems and increase the cost of maintaining aqueous systems in good working condition. Problems caused by scale deposits include obstruction to liquid flow, resistance to conduction, coating of metal parts, reduced equipment life, localized corrosion attack, reduced effectiveness of corrosion inhibitors, and sudden equipment shutdown. can be mentioned.

These problems include water or oil sumps, water piping, steam power equipment, water desalination equipment, reverse osmosis with aqueous solutions, heat exchange equipment, and the transfer of products and by-products into aqueous media (e.g. electricity production). This can occur in equipment related to the transfer of fly ash (generated by the combustion of coal). The temperature range in the operation of these devices is wide, for example, ambient temperatures are used for cooling water and elevated temperatures are used for steam powered equipment.

One method used to overcome the disadvantages of scale formation involves disassembling the equipment to allow for removal of accumulated deposits. This measure is expensive and does not prevent scale redeposition. Another method involves the use of strong alkaline solutions specifically for the removal of sulfate scale. It is claimed that under suitable conditions of temperature and time, alkaline treatment results in an initial destruction of the scale, which can then be removed by mechanical means. Such methods require considerable time and removal of scale for subsequent processing is often difficult.

Another means involves the use of mineral acids to prevent or remove calcium carbonate scale. However, this method increases corrosion of the equipment.

Therefore, there is a need in this field for compositions that can be added in very small amounts to water or aqueous systems to reduce the rate at which insoluble salts precipitate over a wide temperature range, and to further disperse these precipitating insoluble salts. There is. Furthermore, it is preferred that whatever scale forms, it can be removed from the surface by simple mechanical means.

A number of additives have been proposed for addition to water or aqueous systems for these purposes, in particular certain phosphoric acids and polycarboxylic acids; On the contrary, certain polycarboxylic acids, such as polyacrylic acid, have the disadvantage of producing a hard, sticky, eggshell-like scale.

However, if water treatment methods involving heat are used,
As temperatures increase and boron 1317 acid additives are easily hydrolyzed at elevated temperatures, resulting in insoluble precipitates of calcium orthophosphate and other calcium phosphates, their usefulness is considerably limited. Ru.

Furthermore, most commercial equipment, such as industrial boilers, cooling water systems, gas mixing equipment, slurry equipment, such as clay slurry equipment, require that the various solid substances found in the water used within the equipment be suspended or dispersed. It is important to maintain

If such solids are no longer suspended in the liquid, equipment fouling can occur, for example in so-called "transient cooling systems." If there is a sufficient supply of water in the immediate vicinity of the industrial equipment, cooling is often accomplished by running water through the heat transfer device f and then returning the water to its source. however,
Due to the large amount of water used in this system, from an economic standpoint, it is usually not desirable to filter the water. Therefore,
Deposit formation easily occurs within the equipment and it is usually necessary to periodically stop its operation for cleaning purposes. Furthermore, equipment corrosion can result in the deposition of iron oxides and/or iron salts, which can lead to equipment blockage and mechanical failure if not carefully controlled.

Another problem is the build-up of silt and mud that clings to the bottom of water storage tanks and the ballast tanks of ships and ships, thereby reducing the economics of maintaining and operating the ship.

Yet another problem concerns the undesirable deposits from aqueous systems on the metal surface that occur during coating with the oxide layer produced by the cathode on the aluminum. During such coating, hot or boiling water is used, so that not only the pores of the oxide layer are blocked, but also a thin velvety coating (coating silt) is formed over the entire surface. There is a need for improved coated silt inhibitors.

Polymaleic anhydride is a known compound and can be made by any of a number of known methods. British Patent Specification No. 1024725 states:
For example, the polymerization of maleic anhydride (dissolved in an inert organic solvent) in the presence of free radical catalysts has been described. A similar method is described in British Patent Specification No. 1)
No. 95146.

The polymerized maleic anhydride so produced is very easily hydrolyzed, e.g. by heating with water, contains free carboxylic acid groups, and the polymerized maleic anhydride contains some residual anhydride groups on the carbon core. give sexual products.

GB 1369429 describes low molecular weight hydrolyzed polymaleic anhydrides (or water-soluble salts thereof) as scale inhibitors in aqueous systems. British Patent Ming+S*No. 1414918
Hydrolyzed comonomers of maleic anhydride and comonomers such as vinyl acetate and ethyl acrylate are described in this issue as scale inhibitors in aqueous systems.

[Means for solving problems]

We have now discovered that certain partial esters of maleic acid polymers are also valuable scale inhibitors for use in aqueous systems, and are also effective as particulate dispersants and coating antisiltants. Ta.

Therefore, the present invention provides homo- and/or maleic acid in an aqueous system.
or a water-bathable partial ester of the copolymer [herein,
Up to 50 carboxylic acid groups present in the maleic acid polymer have the formula -aotrtt (where horse has 1 to 12 carbon atoms and is substituted by one or more hydroxyl groups). and/or may be interrupted by up to 6 oxygen atoms: or R1: where each 1 is the same or different and represents a hydrogen atom or a methyl group, and n has a value of 5 or Q, and R
1 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms), and the non-esterified carboxylic acid group in the partial ester has the formula -〇〇, M
(In the formula, M represents a hydrogen atom, an alkali metal, an alkaline earth metal, or may be a substituted ammonium group)
to prevent the formation of scale on metal surfaces and/or facilitate the dispersion of particulate matter in the aqueous system and/or the deposition of adherent dirt by the addition of a substantially effective amount of The present invention relates to an aqueous treatment method that is brought into contact with a gold IA surface in order to prevent this.

Preferred structures for birds are straight-chain or branched alkyl groups having 1 to 12 carbon atoms, substituted by one or more hydroxyl groups.

The maleic acid polymer from which the partial ester is formed can be a homo- or copolymer of maleic acid or maleic anhydride.

Homopolymers of maleic acid or maleic anhydride are used for the formation of partial esters; such homopolymers preferably have a molecular fl range of 300 to 5ooo.

A preferred copolymer of maleic acid or maleic anhydride is an optionally hydrolyzed copolymer of maleic anhydride and a monoethylenically unfaded monomer or mixture of monomers, molecular weight 300-50 Ot? It is a copolymer with Examples of preferred copolymers and their preparation are described in British Patent No. 1414918.

These have a molar ratio of maleic anhydride to other monomers of 2.5:1 to 100:1. Especially 2.5:
1 to 5:1 and a molecular weight of 1000 or less. Examples of preferred comonomers include ethylene, styrene, ethyl acetate and vinyl acetate.

Examples of bases include methyl group, ethyl group, n-propyl group, inpropyl group, n-butyl group, n-hexyl group,
n-octyl group, n-tecylti and n-)'tecyl group: 2-hydroΦdiethyl group, 2-hydroxypropyl group, L2-dihydroxypropyl group, 3-hydroxybutyl group and 10-hydroxydecyl group: polypropylene Glycol residue or polyethylene glycol residue (each has a molecular weight of 300 or less), such as triethylene glycol; 2
-Hydroxy-2-phenyl-ethyl group: 2-methoxyethyl group: 2-ethoxyethyl group: 2-butoxyethyl group: or R1 is a residue represented by the following formula:
(wherein R,1) and R1 have the same meanings as defined above.

Examples of birds include methyl group, ethyl group, inpropyl group,
The t-butyl group, the ttL5-tetramethylbutyl group, the nonyl group (based on the nonene mixture), and the dodecyl group (based on the dodecene mixture) are included.

The non-esterified carboxylic acid group in the partial ester of the present invention has the formula -00tMC where M is a hydrogen atom, an alkali metal,
represents an alkaline earth metal or an optionally substituted ammonium group).

The partial ester may be, for example, a) a maleic anhydride polymer or copolymer,
b) Maleic anhydride is reacted with an alcohol represented by 1 (in the formula, "melon" has the same meaning as above) and optionally hydrolyzed to give a partial ester. or copolymerized with a di-ester (wherein the ester moiety is derived from the alcohol R,-OH, optionally in the presence of a mono-ethylenically unsaturated monomer or mixture of monomers as defined above) and as desired. or C) by reacting the polymaleic acid mono- or copolymers with alkylene oxides such as ethylene oxide, propylene oxide or styrene oxide.

Partial esters are effective in preventing scale deposition and salt precipitation from aqueous solutions. Scales formed from salts are derived from calcium, magnesium, barium or strontium field ions and, for example, sulfate, carbonate, hydroxide, phosphate or silicate anions.

Partial esters include calcium sulfate, magnesium hydroxide,
Effective in preventing calcium phosphate and calcium carbonate scale deposition and calcium phosphate sludge dispersion.

In practice, the amount of partial ester used to treat a metal surface, eg added to an aqueous system in contact with a gold jtAR surface, will vary depending on the retention effect required. For purely scale prevention purposes, the amount of partial ester used is usually 1 to 200 ppm based on the aqueous system;
Preferably it is 1 to 50 ppm.

The amount of partial ester used as a dispersant in the process of the present invention for treating relatively very dilute aqueous dispersions may contain up to 70% solids based on the total weight of the aqueous system. Usually 1 to 2 millionths of the total weight of
00. Preferably it is 2 to 20 parts.

When used as an anti-clogging agent for aqueous sealing solutions, the amount of partial ester of the present invention is typically used in the sealing process to treat the oxide layer created by the negative electrode on the aluminum surface. c for the aqueous solution
It is within the range of Looos to α51/l.

Aqueous systems that can be treated according to the present invention, particularly those related to scale prevention treatment, include cooling water systems, air conditioning systems, steam generation systems, seawater evaporators, hydrostatic furnaces, gas mixing systems, closed circuit thermal systems, and water system standards. Examples include refrigeration systems and lower sump systems.

The inhibitors used in this invention can be used alone or in combination with other compounds known to be useful in the treatment of aqueous systems. In the treatment of systems such as cooling water systems, air conditioning systems, steam generation systems, seawater evaporation systems, hydrostatic furnaces, and closed circuit thermal or refrigeration systems, corrosion inhibitors may be used, for example, water-soluble zinc salt diphosphates; Acid salts: Phosphonic acids and their salts, such as acetodiphosphonic acid, nitrilotrismethylenephosphonic acid and methylaminodimethylenephosphonocarboxylic acid and their salts, such as those described in German Patent Application No. 1, 2007-112002, hydroxyphosphonoacetic acid, 2-phosphonobutane. Chromates such as sodium chromate; nitrates such as sodium nitrate; nitrites such as nitrite; molybdates such as molybdenum; Sodium acid: tungstate, e.g. sodium tungstate; silicate, e.g. silicate) IJum: benzotriazole,
bis-benzotriazole or tone-activated benzotriazole or toltriazole derivatives or Mannich base derivatives thereof; aliphatic amines; and polycarboxylic acids such as polymaleic acid and polyacrylic acid, and their respective alkali metal salts, maleic anhydrides. Use of copolymers such as copolymers of maleic anhydride and sulfonated styrene, copolymers of acrylic acid such as copolymers of acrylic acid and hydroxyalkylated acrylic acids, and substituted derivatives of polymaleic acid and polyacrylic acids and copolymers thereof, etc. I can do it. Additionally, the inhibitors used in the present invention may be combined with other dispersing and/or limiting agents, such as polymerized acrylic acids (or salts thereof), phosphino-polycarboxylic acids (UK Patent No. 145,825).
5), hydrolyzed polyacrylonitrile, polymerized hypomethacrylic acid and its salts, polyacrylamide and its copolymers with acrylic and methacrylic acids, ligninsulfonic acid and its salts, tannins , naphthalene sulfonic acid/formamide condensation products, starches and their derivatives, cellulose, acrylic acid/lower alkyl hydroxyacrylate copolymers such as those described in U.S. Pat. No. 4,029,577, styrene/maleic anhydride copolymers and hisulfones. Styrene homopolymers such as those described in U.S. Pat. No. 4,574,755 as well as combinations thereof can be used. Specific limiting agents include, for example, 2-phosphonobutane-12,4-tricarboxylic acid, acetodiphosphonic acid,
Hydrolyzed polymaleic anhydrides and their salts, alkylphosphonic acids, hydroxyphosphonoacetic acid 1-aminoalkyl-1)-diphosphonic acids and their salts, and alkali metal polyphosphonates can also be used.

The inhibitor of the present invention is also used in European Patent No. 01) 8970
Compounds disclosed in the formula 1 or the following formula: and B represents a hydrogen atom or a remainder: in the above formula,
m and n are integers in which the sum of m and n is 3 to 100.

The n:m ratio of 99:1 to 1:99 makes the resulting telomer water-soluble, and m and/or n in the balance B can be the same or different from m and/or n in the balance B. ;R represents a hydrogen atom, a methyl group or an ethyl group; R1
represents the remainder -0X (in the formula, X represents a hydrogen atom, an alkali or alkaline earth metal, ammonium, or an amine residue): R1 is a hydrogen atom, a methyl group, or the remainder -○○! R1 (wherein R1 represents a hydrogen atom or a linear or branched alkyl residue having 1 to 8 carbon atoms optionally substituted by a hydroxyl group);
is a hydrogen atom, a linear or branched alkyl residue -00,R
, (wherein - is a hydrogen atom, the remainder represented by the following formula: -(OHs -OH(B,) 0
)z H (wherein R1 represents a hydrogen atom, a methyl group or a phenyl group, and 2 represents an integer from 1 to 2o), or R1 optionally represents a hydroxyl group or a group -80, M represents a straight-chain or branched alkyl residue having 1 to 8 carbon atoms substituted by a hydrogen atom or an alkali or alkaline earth metal atom; Remainder -00t & C In the formula, R1 has the same meaning as above t! ! ), optionally carboxylic acid group 1 (Il or 2
straight-chain or branched alkyl residues having 1 to 8 carbon atoms, phenyl residues, acetyl residues, hydroxymethyl groups, acetomethyl residues, -
80,M, -OH,-80,M or -PO,M, group (
(wherein M represents a hydrogen atom or an alkali metal or alkaline earth metal atom), the remainder -0ON to R1 (wherein and R4 are the same or different, and each has a hydrogen atom and 1 to 8 carbon atoms) A linear or branched alkyl residue having a hydroxymethyl group, a residue -0H-(OH)00!
M, −0(OH,), OH,PO,M, and d −
0-(0Hs)t OHt SOs M (in the formula, M represents the same meaning as above), or -N (Rqo) 0
OOH4 group (in the formula, RQ.

represents a hydrogen atom or a straight or branched alkyl group having 1 to 4 carbon atoms, provided that R1 represents a hydrogen atom,
And R4 is 00. When representing an H group, it can be used together with cotelomeric compounds in which R is not identical to avian.

Precipitating agents such as alkali metal orthophosphates, carbonates, oxygen scavengers such as alkali metal sulphites and hydrazine; sequestering agents such as nitrilo); IJ acetic acid and its salts; antifoaming agents such as silicones such as polydimethylsiloxane, distearyl sebacic acid. amides, distearyl adipamide and related products derived from ethylene oxide and/or propylene oxide condensates, as well as fatty alcohols such as caprylic alcohol and its ethylene oxide condensates: and fungicides such as amines, quaternary ammonium compounds, chlorophenols. , sulfur-containing compounds such as sulfones, methylene bisthiocyanates and carbamates, inthiazolones, brominated propionamides, triazines, phosphonium compounds, chlorine and chlorine releasing agents and organometallic compounds such as tributyltin oxide.

Partial esters also contain common deposits such as iron oxides and/or
or iron salts, calcium and magnesium deposits such as their carbonates, sulphates, shaleates and phosphates, and dispersants and/or for silts, aluminas, silicates and clays found in such waters. Or act as an antifouling agent.

In particular, the method of the invention can be applied to disperse deposits in aqueous systems containing 5 to 1500 ppm by weight of calcium ions as well as suspended solids.

The above aspects of the invention find particular application in the clay industry where it is important to obtain a slurry that does not appreciably separate during transportation from clay storage to the user. Under the high concentration of suspended solids in these slurries, the partial esters of the present invention disperse the clay 7° within the apparatus.

It was found that it is suitable for M as a dispersant and crushing aid.

The method of the invention can also be applied to prevent the formation of undesired aluminum hydroxide layers (sequestering silts) during the sealing of the oxide layer produced by the cathode on aluminum or its alloys. It can therefore be added as a sequestering anti-silting agent in the aqueous solution used to seal the sub-oxide layer created by the negative electrode on the aluminum (alloy) surface. Such solutions usually have a pH of 4 to 8 and are used at 90-100°C.

〔Example〕

The invention will be explained in further detail in the following examples.

Example A: 49 g of maleic anhydride in 75 g of xylene was reacted with 16 g of di-tert-butyl peroxide as a catalyst.
A suspension of polymaleic anhydride in xylene is prepared by polymerizing for 5 hours at 30°C. The resulting polymer solution was heated at 80°C and then propane-1,2-
Diol 19Il ((L25 mol) and 1
Treat for 30 minutes and then with water ysy for 30 minutes. After cooling, the water is separated off and traces of xylene are then removed by distillation, yielding a solution *14A61 with a solids content of 618.

Example B 25 g of polymaleic anhydride and 4.8 g of propane-12-diol in 25 Nl of xylene ((10675 mol)
Heat the stirred suspension at 80° C. for 1 hour. The suspension obtained is treated with 25 ml of water at 80° C. for 30 minutes.

After cooling, the water is separated off and the xylene is then stripped of trace gold by distillation, yielding a solution 645Ii with a solids content of 47.6 s.

Calcium chloride (OaOlt・2H3034) in distilled water
76 salt and disodium hydrogen phosphate (Napl (PO
No. 2 A solution of HlOα9567, ≦-d'J) is called.

1) Amount/volume solutions of each of the products of Preparation Examples A and B, respectively, are prepared in distilled water.

Calcium chloride solution 2 om in distilled water 180014 in a capacity 21 flask, previously washed with hot chromic acid.
and then 2 drops of concentrated hydrochloric acid. 40d of sodium dihydrogen phosphate solution is then added. Bring up the volume of the mixture to 21 with distilled water. 100 aliquots of mixed solution
Place d into a small glass bottle (1) 2m) and tighten the screw cap. To this solution, add a final volume of test solution l1
Add a sufficient amount of 'JM of test compound to give the required concentration of test compound in l(1o ox/).

At this time, a test compound concentration of 10 ppm in the cLlts solution tosudll final solution is given.

A no-additive blank is prepared in a similar manner as above, but without the addition of test compound.

Adjust the pH of the mixed solution to 8.0, then seal the bottle,
The sample is placed in an aqueous solution at 60° C. and left for 24 hours. The sample is removed and then hot filtered through an α22 micron filter. The filtrate was cooled to 20°C and its pH
The value is recorded and its phosphate content is then determined by the following spectroscopic method.

Prepare the following solution: ammonium molybdate solution 175-25.9 ammonium molybdate in distilled water
dissolve. 280 yd of concentrated sulfuric acid (specific gravity t84) are carefully added to 400 m/distilled water while cooling and stirring. After cooling, add the molybdate solution and then dilute the whole to 10001) with distilled water.

B. Tin dichloride solution 2.59% of tin dichloride (SnOJl.2H,O) is dissolved in glycerol 1010014 (126).

Then 6! of disodium hydrogen phosphate solution! A calibration curve graph showing the phosphate concentration of the IL diluted solution is prepared.

Then perform the spectroscopic determination of phosphate concentration as shown below: Aliquot the diluted stock solution (for the calibration curve graph) &
o--or 2.5- aliquots of the filtrate (obtained by the experimental procedure described above) are placed in a standard volume air 501 containing 40xl of distilled water. Ammonium molybdate solution 2.01)1
Add j and mix everything well. Finally, tin dichloride solution 5
Add drops to bring the total volume to 501)7 and then shake the mixture well.

A control sample is made in the same manner as above, but with the exception of phosphate.

Leave for at least 4 minutes to develop blue color and measure optical density (OD) at 690 am in a 4-wound cell. Subtract the control sample value from each test optical density reading.

To create a calibration curve, ppm PO4”-(x-axis) vs. 0;
Create a continuation of D (y-axis), and to determine the phosphate content of the filtrate, directly read the ppm P 04 corresponding to the measured 0, D, from the calibration curve graph, and Multiply the result by two.

% Prevention of Calcium Phosphate Precipitation (1) is expressed by the following relationship: where X represents the PO, content in ppm in the filtrate, and (expressed). The results obtained are summarized in Table I below.

Claims (7)

[Claims] (1) Water-soluble partial esters of maleic acid homo- and/or copolymers in aqueous systems [wherein up to 50% by weight of the carboxylic acid groups present in the maleic acid polymer are of the formula -
CO_2R_1 {wherein R_1 is 1 to 1 carbon atom
2, may be substituted by one or more hydroxyl groups, and/or may be interrupted by up to 6 oxygen atoms; or R_1 has the structure: ▲ Numerical formula, chemical formula, table etc.▼ (In the formula, each R is the same or different and represents a hydrogen atom or a methyl group, n has a value of 0 to 0.5, and R_2 represents a hydrogen atom or 1 to 12 carbon atoms. (represents an alkyl group)
and the unesterified carboxylic acid group in the partial ester has the formula -CO_2-M, where M represents a hydrogen atom, an alkali metal, an alkaline earth metal, or an optionally substituted ammonium group. and/or to prevent the formation of scale on metal surfaces and/or to facilitate the dispersion of particulate matter in an aqueous system and/or by adding a substantially effective amount of A water-based treatment method that is brought into contact with metal surfaces to prevent the buildup of adhering dirt. (2) Up to 25% by weight of the carboxylic acid groups have the formula -CO_2-
2. The process according to claim 1, wherein R_1 has the same meaning as defined in claim 1. (3) R_1 is a methyl group, an ethyl group, an n-propyl group,
Isopropyl group, n-butyl group, n-hexyl group, n-
Octyl group, n-decyl group or n-dodecyl group; 2-hydroxyethyl group, 2-hydroxypropyl group or 3-
Hydroxybutyl group; triethylene glycol; 2-hydroxy-2-phenyl-ethyl group; 2-butoxyethyl group; or residues represented by the following formula: ▲There are numerical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1n and 2. A method according to claim 1, wherein R_2 has the same meaning as defined in claim 1. (4) The method according to claim 1, wherein the partial ester is derived from hydrolyzed polymaleic anhydride. 5. The method of claim 1, wherein the partial ester is derived from a hydrolyzed copolymer of maleic anhydride and one or more ethylenically unsaturated monomers. (6) The method according to claim 1, wherein the partial ester acts as a scale inhibitor and 1 to 200 ppm of the partial ester is added. (7) The method according to claim 1, wherein 1 to 30 ppm of partial ester is added.