CA1338656C - Anti-scale and corrosion inhibitor - Google Patents
Anti-scale and corrosion inhibitorInfo
- Publication number
- CA1338656C CA1338656C CA 535978 CA535978A CA1338656C CA 1338656 C CA1338656 C CA 1338656C CA 535978 CA535978 CA 535978 CA 535978 A CA535978 A CA 535978A CA 1338656 C CA1338656 C CA 1338656C
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- inhibitor
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
A corrosion and scale inhibitor for an aqueous system comprising a blend of chromate, zinc, molybdate, azole, phosphonate and a polymeric anti-foulant. The soluble metallic inhibitors are utilized at very low concentrations while providing improved corrosion inhibition over known compositions.
Description
Field of the Invention This invention relates to a corrosion and scale inhibitor for an aqueous system and to a method of treating an aqueous syste~
with such an inhibitor.
Bac~ground of the Invention In general, aqueous systems can be considered elther scale forming or corrosive. Deposit formation on metal heat transfer surfaces will occur when scale forming waters contact such surfaces~ These deposits will reduce the heat transfer efficiency of the equipment and reduce water flow rates. If this deposi$ layer is non-uniform, porous and contains holidays (breaks in the film) then corrosion will result due to localized hot spots and differential concentration cells. Dissolved corroslves such as chlorides, sulfates, oxygen and carbon dioxide will also aggravate the situation by increasing the rate of deterioration or corros 7.Qn ~ In corrosive waters the latter predominates ove~ scale formation initially. However, once substantial metal loss in the form of metallic ions and oxides occurs and concentrates in the water, deposition of these corrosion products occurs on heat transfer surfaces. Therefore, there is a need for an additive treatment which reduces both scale formation and corrosive attac~ re~ardless of whether the aqueous system is scale forming or corrosive.
~ .
There-are many well known, reported corrosion inhibitors such as chromates, molybdates, nitrites, zinc salts, benzoates, citrates, diamines, sarcosinates, azoles, phosphonates, ortho and polyphosphates. It is also known and reported that many anti-scalants, when used at less than stoichiometric quantities and having either crystal modification properties, sequestration properties and/or increased lag phase induction times for crystallization, can be used in combination with classical corrosion inhibitors, not only ~o reduce scale formation rates, but also to act synergistically in the reduction of corrosion. These mixtures, therefore, afford corrosion inhibitory properties equivalent to or better than an individual corrosion inhibitor component at a much lower concentration.
Examples of known anti-scalants are: polyphosphates, l-hydroxylethylidene-l, l-diphosphonic acid, amino tri (methylene phosphonic acid), 2-phosphonobutane -1, 2, 4 - tricarboxylic acid, ethylenediamine tetra (methylene phosphonic acid), polyacrylates, polyacrylamides, hydrolysed polymaleic anhydride, polymethacrylate, polymethylmethacrylates, and phosphino polycarboxylates.
Summary of the Invention Essentially the invention consists of a corrosion and scale inhibitor for an aqueous system comprising molybdate, zinc, chromate, azole, phosphonate and polymer.
The invention also consists of a method of inhibiting corrosion and scale for an aqueous system comprising the step of introducing into said system molybdate, zinc, chromate, azole, phosphonate and polymer.
nFA~R~ ~ ON OFPRFFF.RRFn FMROn~MF.~
The iL~ tion utilizes a very low, heavy metal inhibilol lUi~ lul~ which p,uvidc,s hllylo~d collosioll rates over the low heavy metal irJhibitor parl~g-s, as well as allowing for direct discL~g~, to regulated and ....i.~ ly treated salli~l~ sewers. The direct liscLa~ , from the treated proeess will contain 1 ppm or less zinc and 1 ppm or less cLu...;.~..., thus colll~lyhlg with the waste liscLal~ ~ lelin~s of re~ tory bodies. An azole is Lcol~ol~lted in the fnnn~ for copper and eopper alloy ~ù~ec1 ;r 1~ The polymers inhibit scale and deposit rO....~1;.... on heat ll~r~,r ~ s. Other metal s,.. r~ ,s are also ",:;;,";~;"rrl in a elean state to enable the collusion inhibitors to filnrtinn under a less stressful e.l~ho,llucu~ and Ihelefole the polymers e .h~,-rc the scale and corrosion inhibiting ~,u~c,lies of the iuv~ tion.
;.
According to one aspect of the present inventlon, there is provided a corrosion and scale lnhlbltor for use ln an aqueous system, said inhibitor comprising: (a) a zinc salt;
(b) an azole; (c) a phosphonate; (d) an anionic polymeric dlspersant; said zlnc salt, azole, phosphonate and anionlc polymerlc dlspersant in amounts effective to inhibit corrosion; (e) less than 3 parts by weight per mlllion parts water of a chromate; and (f) less than 4 parts by weight per million parts water of a molybdate. A further aspect of the invention provides a method for using this inhibitor to inhibit corrosion and scale formation in an aqueous system.
Accordlng to another aspect of the present lnventlon, there is provided a corroslon and scale lnhlbltor for use in an aqueous system, sald lnhlbltor comprlsing: (a) 1 part by weight per million parts of water of a zinc salt;
(b) 2 parts by weight per mlllion parts of water of a chromate; (c) 3 parts by weight per million parts of water of a molybdate; (d) 1 part by welght per million parts of water of an azole; (e) 4-5 parts by weight per mlllion parts of water of a phosphonate; and (f) 2-5 parts by welght per mllllon parts of water of an anlonlc polymerlc dlspersant. A
further aspect of the lnventlon provldes a method for uslng thls lnhlbltor to inhlbit corrosion and scale formation ln an aqueous system.
CO~2RO~ON Tl~Hll~rlORY PFRFORMA~(~F
Labolaloly tests were carried out on two water colllpo~ on~ (I & II) under static aeration test ~luce~lules at 70F and 75F. A third water co...l o~ )n (III) was used for ~llallliC aerated cûl~.liliolls under a recirculatory eva~uol~tive cooling process sim~ tion at 95-F to 100F. Table I co.~ the cc....po~;l;on of the waters utili7e( 4a The corrosion rates were assessed using the weight loss method. The metal specimens (i.e. National Association of Corrosion Engineering coupons) were precleaned with isopropyl alcohol and a benzene mixture. The coupons were not pretreated with inhibitor, nor were they initially operated in an elevated inhibitor residual environment for a portion of the trial duration.
Various inhibitor blend packages were evaluated on the three water compositions. Table II lists the various inhibitor blends, the composition of the blend as well as the active residual present in the test waters. The results of the inhibitory performance of the various mixture in test waters I, II and III are listed in Tables III, IV and V respectively. Corrosion rate percentage efficiencies on mild steel were calculated as follows:
Untreated Blank mpy - Inhibitor mpy x 100 Untreated Blank mpy (mpy = mills per year or 1/1000 of an inch metal loss per year).
T A B L E
TEST WATER COMPOSITION
CONSTITUENT (ppm) I II III
Total Hardness as CaCO3 188 138 414 Calcium Hardness as CaCO3 124 104 312 Magnesium Hardness as CaCO3 64 34 102 'M' Alkalinity as CaCO3 202 86 258 Chloride as CL 100 100 96 Sulfate 0 33 100 Iron as Fe 0.65 0.01 0.04 Total Dissolved Solids 260 208 624 Adjusted pH of Trial Runs 8.3 8.3 8.4 Temperature (F) 70-75 70-75 95-100 Ryznar Index 6.65 7.58 5.01 The mild coupon composition was that of 1,020 military steel specification (C = 0.2%, Mn = 0.2 - 0.6%, P = 0.04%, S =
0.05 % Max., Fe = balance) The copper coupon composition was that of electrolytic grade (Federal specification - QQ - C - 576; Cu = 99.9%, Ag trace) T A B L E II
INHIBITOR COMPOSITION
INHIBITOR COMPONENT CONCENTRATION IN TEST WATERS
A l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn B 1-hydroxylethylidene-1, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 10 ppm as CrO4 C l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm sodium molybdate - 7.5 ppm as MoO4 tolyltriazole - 1 ppm D l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm T A B L E II
INHIBITOR COMPOSITION
INHIBITOR COMPONENT CONCENTRATION IN TEST WATERS
E l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 7.5 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm F l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 5 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm G l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 4 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm H l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm T A B L E II
I NH I B I TOR COMPOS I T I ON
INHIBITOR COMPONENT CONCENTRATION IN TEST WATERS
I 2-phosphonobutane-1, 2, 4-tricarboxylic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm J 2-phosphonobutane-1, 2, 4-tricarboxylic acid - 4 ppm zinc chloride . - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm K 2-phosphonobutane-1, 2, 4-tricarboxylic acid - 4 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 5 ppm T A B L E III
CORROSION RATES USING TEST WATER I
CORROSION RATE OF METAL - MLS. PER YEAR (mpy) INHIBITORMILD STEEL COUPONS EFFICIENCY
BLANK 6.48 0 B 0.54 91.7 C 0.50 92.2 E 0.31 95.2 F 0.16 97.5 G 0.21 96.7 H 0.20 96.9 T A B L E IV
CORROSION RATES USING TEST WATER II
CORROSION RATE OF METAL - MLS. PER YEAR (mpy) INHIBITORMILD STEEL COUPON EFFICIENCY
BLANK 8.31 0 A 4.55 45.2 B 1.67 79.9 C 4.71 43.3 D 0.86 89.6 H 0.74 91.1 I 1.81 78.2 J 2.38 71.6 K 1.09 86.9 T A B L E V
CORROSION RATES USING TEST WATER III
CORROSION RATE OF METAL - MLS. PER YEAR (mpy) MILD STEEL
INHIBITOR COPPER COUPON MILD STEEL COUPON % EFFICIENCY
BLANK - 9.68 0 A' - 3.59 62.9 B2 0.17 2.27 76.5 C3 0.25 3.81 60.6 H4 0.05 0.44 95.4 NOTE: 1 - Average of 5 test runs 2 - Average of 14 test runs 3 - Average of 13 test runs 4 - Average of 11 test runs SCALE INHIBITORY PERFORMANCE
The scale inhibitory performance of these blends was also evaluated.
Static tests were performed on calcium carbonate and calcium phosphate precipitation inhibition.
The testing procedures follow.....
CaC03 PRECIPITATION INHIBITION
TOCK SOLUTION 1: 3.25 g/L CaCl2 2 H2O adjusted to pH 8.5 TOCK SOLUTION 2: 2.48 g/L Na2CO3, adjusted to pH 8.5 ROCEDURE:
1. Place the following in a 4-oz. jar:
50 ml Stock Solution 1 50 ml Stock Solution 2 Add inhibitor as specified in Table II
2. Preheat samples in warm (+ 70C) water for 5 minutes 3. Heat in oven 5 hours at 70C; remove and cool to room temperature 4. Filter through 0.45 ,um filter 5. Add 4 ml concentrated HCl to 25 ml filtrate and allow to stand 15+ minutes 6. Dilute to 50 ml with DI H2O
with such an inhibitor.
Bac~ground of the Invention In general, aqueous systems can be considered elther scale forming or corrosive. Deposit formation on metal heat transfer surfaces will occur when scale forming waters contact such surfaces~ These deposits will reduce the heat transfer efficiency of the equipment and reduce water flow rates. If this deposi$ layer is non-uniform, porous and contains holidays (breaks in the film) then corrosion will result due to localized hot spots and differential concentration cells. Dissolved corroslves such as chlorides, sulfates, oxygen and carbon dioxide will also aggravate the situation by increasing the rate of deterioration or corros 7.Qn ~ In corrosive waters the latter predominates ove~ scale formation initially. However, once substantial metal loss in the form of metallic ions and oxides occurs and concentrates in the water, deposition of these corrosion products occurs on heat transfer surfaces. Therefore, there is a need for an additive treatment which reduces both scale formation and corrosive attac~ re~ardless of whether the aqueous system is scale forming or corrosive.
~ .
There-are many well known, reported corrosion inhibitors such as chromates, molybdates, nitrites, zinc salts, benzoates, citrates, diamines, sarcosinates, azoles, phosphonates, ortho and polyphosphates. It is also known and reported that many anti-scalants, when used at less than stoichiometric quantities and having either crystal modification properties, sequestration properties and/or increased lag phase induction times for crystallization, can be used in combination with classical corrosion inhibitors, not only ~o reduce scale formation rates, but also to act synergistically in the reduction of corrosion. These mixtures, therefore, afford corrosion inhibitory properties equivalent to or better than an individual corrosion inhibitor component at a much lower concentration.
Examples of known anti-scalants are: polyphosphates, l-hydroxylethylidene-l, l-diphosphonic acid, amino tri (methylene phosphonic acid), 2-phosphonobutane -1, 2, 4 - tricarboxylic acid, ethylenediamine tetra (methylene phosphonic acid), polyacrylates, polyacrylamides, hydrolysed polymaleic anhydride, polymethacrylate, polymethylmethacrylates, and phosphino polycarboxylates.
Summary of the Invention Essentially the invention consists of a corrosion and scale inhibitor for an aqueous system comprising molybdate, zinc, chromate, azole, phosphonate and polymer.
The invention also consists of a method of inhibiting corrosion and scale for an aqueous system comprising the step of introducing into said system molybdate, zinc, chromate, azole, phosphonate and polymer.
nFA~R~ ~ ON OFPRFFF.RRFn FMROn~MF.~
The iL~ tion utilizes a very low, heavy metal inhibilol lUi~ lul~ which p,uvidc,s hllylo~d collosioll rates over the low heavy metal irJhibitor parl~g-s, as well as allowing for direct discL~g~, to regulated and ....i.~ ly treated salli~l~ sewers. The direct liscLa~ , from the treated proeess will contain 1 ppm or less zinc and 1 ppm or less cLu...;.~..., thus colll~lyhlg with the waste liscLal~ ~ lelin~s of re~ tory bodies. An azole is Lcol~ol~lted in the fnnn~ for copper and eopper alloy ~ù~ec1 ;r 1~ The polymers inhibit scale and deposit rO....~1;.... on heat ll~r~,r ~ s. Other metal s,.. r~ ,s are also ",:;;,";~;"rrl in a elean state to enable the collusion inhibitors to filnrtinn under a less stressful e.l~ho,llucu~ and Ihelefole the polymers e .h~,-rc the scale and corrosion inhibiting ~,u~c,lies of the iuv~ tion.
;.
According to one aspect of the present inventlon, there is provided a corrosion and scale lnhlbltor for use ln an aqueous system, said inhibitor comprising: (a) a zinc salt;
(b) an azole; (c) a phosphonate; (d) an anionic polymeric dlspersant; said zlnc salt, azole, phosphonate and anionlc polymerlc dlspersant in amounts effective to inhibit corrosion; (e) less than 3 parts by weight per mlllion parts water of a chromate; and (f) less than 4 parts by weight per million parts water of a molybdate. A further aspect of the invention provides a method for using this inhibitor to inhibit corrosion and scale formation in an aqueous system.
Accordlng to another aspect of the present lnventlon, there is provided a corroslon and scale lnhlbltor for use in an aqueous system, sald lnhlbltor comprlsing: (a) 1 part by weight per million parts of water of a zinc salt;
(b) 2 parts by weight per mlllion parts of water of a chromate; (c) 3 parts by weight per million parts of water of a molybdate; (d) 1 part by welght per million parts of water of an azole; (e) 4-5 parts by weight per mlllion parts of water of a phosphonate; and (f) 2-5 parts by welght per mllllon parts of water of an anlonlc polymerlc dlspersant. A
further aspect of the lnventlon provldes a method for uslng thls lnhlbltor to inhlbit corrosion and scale formation ln an aqueous system.
CO~2RO~ON Tl~Hll~rlORY PFRFORMA~(~F
Labolaloly tests were carried out on two water colllpo~ on~ (I & II) under static aeration test ~luce~lules at 70F and 75F. A third water co...l o~ )n (III) was used for ~llallliC aerated cûl~.liliolls under a recirculatory eva~uol~tive cooling process sim~ tion at 95-F to 100F. Table I co.~ the cc....po~;l;on of the waters utili7e( 4a The corrosion rates were assessed using the weight loss method. The metal specimens (i.e. National Association of Corrosion Engineering coupons) were precleaned with isopropyl alcohol and a benzene mixture. The coupons were not pretreated with inhibitor, nor were they initially operated in an elevated inhibitor residual environment for a portion of the trial duration.
Various inhibitor blend packages were evaluated on the three water compositions. Table II lists the various inhibitor blends, the composition of the blend as well as the active residual present in the test waters. The results of the inhibitory performance of the various mixture in test waters I, II and III are listed in Tables III, IV and V respectively. Corrosion rate percentage efficiencies on mild steel were calculated as follows:
Untreated Blank mpy - Inhibitor mpy x 100 Untreated Blank mpy (mpy = mills per year or 1/1000 of an inch metal loss per year).
T A B L E
TEST WATER COMPOSITION
CONSTITUENT (ppm) I II III
Total Hardness as CaCO3 188 138 414 Calcium Hardness as CaCO3 124 104 312 Magnesium Hardness as CaCO3 64 34 102 'M' Alkalinity as CaCO3 202 86 258 Chloride as CL 100 100 96 Sulfate 0 33 100 Iron as Fe 0.65 0.01 0.04 Total Dissolved Solids 260 208 624 Adjusted pH of Trial Runs 8.3 8.3 8.4 Temperature (F) 70-75 70-75 95-100 Ryznar Index 6.65 7.58 5.01 The mild coupon composition was that of 1,020 military steel specification (C = 0.2%, Mn = 0.2 - 0.6%, P = 0.04%, S =
0.05 % Max., Fe = balance) The copper coupon composition was that of electrolytic grade (Federal specification - QQ - C - 576; Cu = 99.9%, Ag trace) T A B L E II
INHIBITOR COMPOSITION
INHIBITOR COMPONENT CONCENTRATION IN TEST WATERS
A l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn B 1-hydroxylethylidene-1, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 10 ppm as CrO4 C l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm sodium molybdate - 7.5 ppm as MoO4 tolyltriazole - 1 ppm D l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm T A B L E II
INHIBITOR COMPOSITION
INHIBITOR COMPONENT CONCENTRATION IN TEST WATERS
E l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 7.5 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm F l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 5 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm G l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 4 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm H l-hydroxylethylidene-l, l-diphosphonic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm T A B L E II
I NH I B I TOR COMPOS I T I ON
INHIBITOR COMPONENT CONCENTRATION IN TEST WATERS
I 2-phosphonobutane-1, 2, 4-tricarboxylic acid - 5 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm J 2-phosphonobutane-1, 2, 4-tricarboxylic acid - 4 ppm zinc chloride . - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 2 ppm K 2-phosphonobutane-1, 2, 4-tricarboxylic acid - 4 ppm zinc chloride - 1 ppm as Zn disodium chromate - 2 ppm as CrO4 sodium molybdate - 3 ppm as MoO4 tolyltriazole - 1 ppm maleic anhydride terpolymer - 5 ppm T A B L E III
CORROSION RATES USING TEST WATER I
CORROSION RATE OF METAL - MLS. PER YEAR (mpy) INHIBITORMILD STEEL COUPONS EFFICIENCY
BLANK 6.48 0 B 0.54 91.7 C 0.50 92.2 E 0.31 95.2 F 0.16 97.5 G 0.21 96.7 H 0.20 96.9 T A B L E IV
CORROSION RATES USING TEST WATER II
CORROSION RATE OF METAL - MLS. PER YEAR (mpy) INHIBITORMILD STEEL COUPON EFFICIENCY
BLANK 8.31 0 A 4.55 45.2 B 1.67 79.9 C 4.71 43.3 D 0.86 89.6 H 0.74 91.1 I 1.81 78.2 J 2.38 71.6 K 1.09 86.9 T A B L E V
CORROSION RATES USING TEST WATER III
CORROSION RATE OF METAL - MLS. PER YEAR (mpy) MILD STEEL
INHIBITOR COPPER COUPON MILD STEEL COUPON % EFFICIENCY
BLANK - 9.68 0 A' - 3.59 62.9 B2 0.17 2.27 76.5 C3 0.25 3.81 60.6 H4 0.05 0.44 95.4 NOTE: 1 - Average of 5 test runs 2 - Average of 14 test runs 3 - Average of 13 test runs 4 - Average of 11 test runs SCALE INHIBITORY PERFORMANCE
The scale inhibitory performance of these blends was also evaluated.
Static tests were performed on calcium carbonate and calcium phosphate precipitation inhibition.
The testing procedures follow.....
CaC03 PRECIPITATION INHIBITION
TOCK SOLUTION 1: 3.25 g/L CaCl2 2 H2O adjusted to pH 8.5 TOCK SOLUTION 2: 2.48 g/L Na2CO3, adjusted to pH 8.5 ROCEDURE:
1. Place the following in a 4-oz. jar:
50 ml Stock Solution 1 50 ml Stock Solution 2 Add inhibitor as specified in Table II
2. Preheat samples in warm (+ 70C) water for 5 minutes 3. Heat in oven 5 hours at 70C; remove and cool to room temperature 4. Filter through 0.45 ,um filter 5. Add 4 ml concentrated HCl to 25 ml filtrate and allow to stand 15+ minutes 6. Dilute to 50 ml with DI H2O
7. Add 3 ml 50% NaOH
8. Add Ca+2 indicator 9. Titrate with EDTA to purple-violet endpoint STANDARD CALCIUM PHOSPHATE PRECIPITATION INHIBITION
l. For each test sample, add the following to a 4-oz. jar:
(a) 50 ml of 12 ppm Na2HPO4 as PO4 3 (b) Add inhibitor as specified in Table II
(c) 50 ml of 500 ppm CaCl2 as CaCO3 (with 5 mg/L Fe+3 added) 2. Adjust each sample to the appropriate pH with dilute NaOH ( ~ 1%) 3. Place lid on sample jars and store in a 70C oven for 17 hours 4. Remove samples from oven one at a time and filter each sample through a 0.22 ~m millipore filter immediately after it is removed from the oven 5. Allow samples to cool to room temperature 6. Dilute samples by placing 30 ml of test sample into a 100 ml volumetric and QS with DI H2O
7. Spectrophotometrically analyze the dilute samples for PO4+3 concentration by the ascorbic acid method (APHA
Standard Methods, 13th. Ed. 532 (1971): Hach spectrophoto-meter at 700 NM; Phosver III phosphate reagent).
FINAL CONCENTRATIONS:
+2 250 ppm Ca , as CaCO3 6 ppm PO4~3 2.5 ppm Fe+3 The respective results are listed in Tables VI and VII.
SCALE INHIBITOR PERFORMANCE
Percent inhibition and percentage efficiency were calculated as follows:
Treated Sample Result x 100 % Inhibitin = Stock Solution ImpuritY
where the impurity is either calcium carbonate, or calcium phosphate Inhibitor % Inhibition - Blank % Inhibition x 100 Efficiency = Blank Percent Inhibition for calcium carbonate inhibition tests Efficiency = Inhibitor % Inhibition - Blank % Inhibition for calcium phosphate inhibition tests T A B L E VI
CALCIUM CARBONATE PRECIPITATION RESULTS
PERCENT
INHIBITOR INHIBITION % EFFICIENCY
Blank 57.2 0 l-hydroxylethylidene-l, 1- diphosphonic acid 5 ppm 76.8 34.2 2-phosphonobutane-1, 2, 4-tricarboxylic acid 4 ppm 77.5 35.5 Polymaleic anhydride 2 ppm 86.9 51.9 terpolymer 4 ppm 88.4 54.5 B 76.8 34.2 H 80.6 40.9 K 84.7 48.1 -T A B L E VII
CALCIUM PHOSPHATE PRECIPITATION RESULTS
PERCENT
INHIBITOR INHIBITION % EFFICIENCY
Blank 1.7 0 l-hydroxylethylidene-l, l-diphosphonic acid 5 ppm 54.2 52.5 2-phosphonobutane-1, 2, 4-tricarboxylic acid 4 ppm 75.0 73.3 Polymaleic anhydride 2 ppm 69.2 67.5 terpolymer 4 ppm 95.8 94.1 B 54.2 52.5 H 71.7 70.0 K 98.0 96.3 Although the foregoing examples demonstrate corroslon lnhlbltlng compositions whlch utlllze zlnc from zinc chlorlde, the zlnc may also be selected from the group conslstlng of zlnc nltrate, zlnc sulphate or zinc acetate.
Further, the chromate may be selected from the group conslstlng of sodium chromate or dlsodlum chromate.
The azole may be elected from the group conslstlng of 1,2,3-tolyltrlazole, 1,2,3-benzotrlazole or sodlum 2-mercaptobenzothlazole.
The phosphonate may be selected from the group conslstlng of l-hydroxylethylldene-l,l-dlphosphonlc acld, 2-phosphonlc acld, 2-phosphonobutane-1,2 t 4-trlcarboxyllc acld or hydroxyphosphonocarboxyllc acld.
Further, the polymer may be selected from the group conslstlng of polymalelc anhydrlde terpolymer, polymethacrylate, polyacrylate, polyacrylate copolymer, sulfonated polystyrene/malelc anhydrlde copolymer and acrylamlde/acrylate copolymer, said group of polymers having an average number molecular welght from about 1,000 to 10,000.
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. ~"
l. For each test sample, add the following to a 4-oz. jar:
(a) 50 ml of 12 ppm Na2HPO4 as PO4 3 (b) Add inhibitor as specified in Table II
(c) 50 ml of 500 ppm CaCl2 as CaCO3 (with 5 mg/L Fe+3 added) 2. Adjust each sample to the appropriate pH with dilute NaOH ( ~ 1%) 3. Place lid on sample jars and store in a 70C oven for 17 hours 4. Remove samples from oven one at a time and filter each sample through a 0.22 ~m millipore filter immediately after it is removed from the oven 5. Allow samples to cool to room temperature 6. Dilute samples by placing 30 ml of test sample into a 100 ml volumetric and QS with DI H2O
7. Spectrophotometrically analyze the dilute samples for PO4+3 concentration by the ascorbic acid method (APHA
Standard Methods, 13th. Ed. 532 (1971): Hach spectrophoto-meter at 700 NM; Phosver III phosphate reagent).
FINAL CONCENTRATIONS:
+2 250 ppm Ca , as CaCO3 6 ppm PO4~3 2.5 ppm Fe+3 The respective results are listed in Tables VI and VII.
SCALE INHIBITOR PERFORMANCE
Percent inhibition and percentage efficiency were calculated as follows:
Treated Sample Result x 100 % Inhibitin = Stock Solution ImpuritY
where the impurity is either calcium carbonate, or calcium phosphate Inhibitor % Inhibition - Blank % Inhibition x 100 Efficiency = Blank Percent Inhibition for calcium carbonate inhibition tests Efficiency = Inhibitor % Inhibition - Blank % Inhibition for calcium phosphate inhibition tests T A B L E VI
CALCIUM CARBONATE PRECIPITATION RESULTS
PERCENT
INHIBITOR INHIBITION % EFFICIENCY
Blank 57.2 0 l-hydroxylethylidene-l, 1- diphosphonic acid 5 ppm 76.8 34.2 2-phosphonobutane-1, 2, 4-tricarboxylic acid 4 ppm 77.5 35.5 Polymaleic anhydride 2 ppm 86.9 51.9 terpolymer 4 ppm 88.4 54.5 B 76.8 34.2 H 80.6 40.9 K 84.7 48.1 -T A B L E VII
CALCIUM PHOSPHATE PRECIPITATION RESULTS
PERCENT
INHIBITOR INHIBITION % EFFICIENCY
Blank 1.7 0 l-hydroxylethylidene-l, l-diphosphonic acid 5 ppm 54.2 52.5 2-phosphonobutane-1, 2, 4-tricarboxylic acid 4 ppm 75.0 73.3 Polymaleic anhydride 2 ppm 69.2 67.5 terpolymer 4 ppm 95.8 94.1 B 54.2 52.5 H 71.7 70.0 K 98.0 96.3 Although the foregoing examples demonstrate corroslon lnhlbltlng compositions whlch utlllze zlnc from zinc chlorlde, the zlnc may also be selected from the group conslstlng of zlnc nltrate, zlnc sulphate or zinc acetate.
Further, the chromate may be selected from the group conslstlng of sodium chromate or dlsodlum chromate.
The azole may be elected from the group conslstlng of 1,2,3-tolyltrlazole, 1,2,3-benzotrlazole or sodlum 2-mercaptobenzothlazole.
The phosphonate may be selected from the group conslstlng of l-hydroxylethylldene-l,l-dlphosphonlc acld, 2-phosphonlc acld, 2-phosphonobutane-1,2 t 4-trlcarboxyllc acld or hydroxyphosphonocarboxyllc acld.
Further, the polymer may be selected from the group conslstlng of polymalelc anhydrlde terpolymer, polymethacrylate, polyacrylate, polyacrylate copolymer, sulfonated polystyrene/malelc anhydrlde copolymer and acrylamlde/acrylate copolymer, said group of polymers having an average number molecular welght from about 1,000 to 10,000.
~;
. ~"
Claims (24)
1. A corrosion and scale inhibitor for use in an aqueous system, said inhibitor comprising:
(a) a zinc salt;
(b) an azole;
(c) a phosphonate;
(d) an anionic polymeric dispersant;
said zinc salt, azole, phosphonate and anionic polymeric dispersant in amounts effective to inhibit corrosion;
(e) less than 3 parts by weight per million parts water of a chromate; and (f) less than 4 parts by weight per million parts water of a molybdate.
(a) a zinc salt;
(b) an azole;
(c) a phosphonate;
(d) an anionic polymeric dispersant;
said zinc salt, azole, phosphonate and anionic polymeric dispersant in amounts effective to inhibit corrosion;
(e) less than 3 parts by weight per million parts water of a chromate; and (f) less than 4 parts by weight per million parts water of a molybdate.
2. The inhibitor of claim 1 wherein said anionic polymeric dispersant is selected from the group consisting of polymaleic anhydride terpolymer, polymethacrylate, polyacrylate, polyacrylate copolymer, sulfonated polystyrene/maleic anhydride copolymer and acrylamide/acrylate copolymer, said group of polymers having an average number molecular weight from about 1,000 to 10,000.
3. The inhibitor of claim 1 wherein said anionic polymeric dispersant is maleic anhydride terpolymer.
4. The inhibitor of claims 1, 2 or 3 wherein the concentration of said anionic polymeric dispersant is 2-20 parts by weight per million parts of water.
5. The inhibitor of claim 1 wherein the concentration of said chromate is about 2 parts by weight per million parts of water.
6. The inhibitor of claim 1 wherein the concentration of said molybdate is about 3 parts by weight per million parts of water.
7. The inhibitor of claim 1 wherein said phosphonate is either 1-hydroxylethylidene-1,1-diphosphonic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
8. The inhibitor of claims 1 or 7 wherein the concentration of said phosphonate is about 2-20 parts by weight per million parts of water.
9. A method for inhibiting corrosion and scale formation in an aqueous system comprising use in said aqueous system of the inhibitor of claim 1.
10. The method of claim 9 wherein said anionic polymeric dispersant is selected from the group consisting of polymaleic anhydride terpolymer, polymethacrylate, polyacrylate, polyacrylate copolymer, sulfonated polystyrene/maleic anhydride copolymer and acrylamide/acrylate copolymer, said group of polymers having an average number molecular weight from about 1,000 to 10,000.
11. The method of claim 9 wherein said anionic polymeric dispersant is maleic anhydride terpolymer.
12. The method of claims 9, 10 or 11 wherein the concentration of said anionic polymeric dispersant is 2-20 parts by weight per million parts of water.
13. The method of claim 9 wherein the concentration of said chromate is about 2 parts by weight per million parts of water.
14. The method of claim 9 wherein the concentration of said molybdate is about 3 parts by weight per million parts of water.
15. The method of claim 9 wherein said phosphonate is either 1-hydroxylethylidene-1,1-diphosphonic acid or 2-phosphonate-1,2,4-tricarboxylic acid.
16. The method of claims 9 or 15 wherein the concentration of said phosphonate is about 2-20 parts by weight per million parts of water.
17. A corrosion and scale inhibitor for use in an aqueous system, said inhibitor comprising:
(a) 1 part by weight per million parts of water of a zinc salt;
(b) 2 parts by weight per million parts of water of a chromate;
(c) 3 parts by weight per million parts of water of a molybdate;
(d) 1 part by weight per million parts of water of an azole;
(e) 4-5 parts by weight per million parts of water of a phosphonate; and (f) 2-5 parts by weight per million parts of water of an anionic polymeric dispersant.
(a) 1 part by weight per million parts of water of a zinc salt;
(b) 2 parts by weight per million parts of water of a chromate;
(c) 3 parts by weight per million parts of water of a molybdate;
(d) 1 part by weight per million parts of water of an azole;
(e) 4-5 parts by weight per million parts of water of a phosphonate; and (f) 2-5 parts by weight per million parts of water of an anionic polymeric dispersant.
18. The inhibitor of claim 17 wherein said anionic polymeric dispersant is selected from the group consisting of polymaleic anhydride terpolymer, polymethacrylate, polyacrylate, polyacrylate copolymer, sulfonated polystyrene/maleic anhydride copolymer and acrylamide/acrylate copolymer, said group of polymers having an average number molecular weight from about 1,000 to 10,000.
19. The inhibitor of claim 17 wherein said anionic polymeric dispersant is maleic anhydride terpolymer.
20. The inhibitor of claim 17 wherein said phosphonate is either 1-hydroxylethylidene-1,1-disphosphonic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
21. A method for inhibiting corrosion and scale formation in an aqueous system comprising use in said aqueous system of the inhibitor of claim 17.
22. The method of claim 21 wherein said anionic polymeric dispersant is selected from the group consisting of polymaleic anhydride terpolymer, polymethacrylate, polyacrylate, polyacrylate copolymer, sulfonated polystyrene/maleic anhydride copolymer and acrylamide/acrylate copolymer, said group of polymers having an average number molecular weight from about 1,000 to 10,000.
23. The method of claim 21 wherein said anionic polymeric dispersant is maleic anhydride terpolymer.
24. The method of claim 21 wherein said phosphonate is either 1-hydroxylethylidene-1,1-disphosphonic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 535978 CA1338656C (en) | 1987-04-29 | 1987-04-29 | Anti-scale and corrosion inhibitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 535978 CA1338656C (en) | 1987-04-29 | 1987-04-29 | Anti-scale and corrosion inhibitor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1338656C true CA1338656C (en) | 1996-10-22 |
Family
ID=4135544
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 535978 Expired - Fee Related CA1338656C (en) | 1987-04-29 | 1987-04-29 | Anti-scale and corrosion inhibitor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1338656C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2331999A (en) * | 1997-10-28 | 1999-06-09 | Ibm | Copper preservative treatment using azoles |
| CN115074091A (en) * | 2022-07-08 | 2022-09-20 | 陶普斯化学科技(北京)有限公司 | Long-acting anti-acidification high-efficiency secondary refrigerant and preparation method thereof |
-
1987
- 1987-04-29 CA CA 535978 patent/CA1338656C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2331999A (en) * | 1997-10-28 | 1999-06-09 | Ibm | Copper preservative treatment using azoles |
| GB2331999B (en) * | 1997-10-28 | 2003-01-22 | Ibm | Copper preservative treatment |
| CN115074091A (en) * | 2022-07-08 | 2022-09-20 | 陶普斯化学科技(北京)有限公司 | Long-acting anti-acidification high-efficiency secondary refrigerant and preparation method thereof |
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