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
  • C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
  • C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
  • C02F5/105—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances combined with inorganic substances
• • 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
• • 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
  • C02F2303/08—Corrosion inhibition

Definitions

• the instant invention is directed to a process of inhibiting corrosion of iron surfaces in contact with cooling waters. More specifically, the subject invention relates to compositions which inhibit corrosion of iron in presence of cooling waters by aiding in formation of a protective iron oxide film over the iron substrate.
• a chemical composition In order to somehow aid formation of a protective iron oxide film, a chemical composition must not form strong complexes or chelates with soluble iron species which would increase the demand for iron in the cooling water and thereby increase corrosion rates. Yet, such a composition must be able to react with or absorb on iron or the iron oxides at the iron surface to control the crystallinelike growth and habit of the oxides. Also, a chemical treating agent when added to the cooling water system as a corrosion inhibiting substance must be able to reach the metal surface under attack or at least make a very close approach to the surface, certainly within the ionic double layer, while still in active form.
• a useful chemical anticorrosive material should be able to help produce an ideal oxide film in a quick and efficient manner by a facile, close approach to an iron surface to which it can at tach itself or be in close proximity,
• the additive would then be able to absorb or react with iron species just formed through the additives active sites, thereby enhancing filming on the iron or steel surface to be protected.
• Another object is to provide cooling water compositions which will promote formation of a protective iron oxide film upon the surfaces of corrodible iron metals and thereby control the diffusion of oxygen to the free iron metal surface which is susceptible to its corrosive effects.
• a special object of the invention is to provide a combination of compounds in a single composition which will protect corrodible iron surfaces in the presence of cooling water over long periods of time even at relatively low dosages, which compositions are not quickly depleted of activity by rapid reaction of their active sites with water dispersible iron speones.
• a corrosion-inhibiting composition comprising a chelating system which includes both a water-dispersible tannin and an HCN modified lignosulfonate or naphthalene sulfonate and a masking agent for the chelating system which comprises a multivalent metal
• a corrosion-inhibiting composition comprising a chelating system which includes both a water-dispersible tannin and an HCN modified lignosulfonate or naphthalene sulfonate and a masking agent for the chelating system which comprises a multivalent metal
• the specific compounds making up the sum total corrosioninhibiting composition may be added to a cooling water separately, or they may be combined into a single product in either liquid or granular form, or in the form of a shaped article of manufacture, e.g., a water-treating ball.
• the subject composition may be readily formed into compact balls which may then be conveniently added to the cooling water.
• the chelating system which is added to the cooling water in order to complex or tie up water-dispersible iron species existing in the cooling water includes a water-dispersible tannin and an HCN modified lignosulfonate or naphthalene sulfonate.
• water-Dispersible Tannin Substituents are those which have been modified by a variety of synthetic method by reaction of natural tannins with various chemical reagents. Mixtures of these modified tannins may also be used in preparing the subject compositions.
• the tannins have been divided into two principal groups the catechol tannins and the pyrogallol tannins. After dry distillation the catechol tannins yield catechol as a principal product of decomposition, and the pyrogallol tannins after dry distillation yield pyrogallol. Solutions containing catechol give a greenish-black precipitate with ferric salts, whereas solutions containing pyrogallol tannins give a bluish-black precipitate with ferric salts. In general, only pyrocatechol derivatives are found in catechol tannins, whereas gallic acid is always present in pyrogallol tannins.
• the preferred tannins for use in the subject process are the catechol tannins although pyrogallol tannins can also be used in the process.
• Natural tannins can be obtained from a number of materials.
• One of the principal sources is the quebracho trees, the wood of which contains about 20 to 23 percent easily extractable tannin of the catechol type.
• Other sources include chestnut wood, redwood bark. divi-divi pods, mangrove bark cutch (one of the preferred sources along with quebracho trees), wattle bark, gallnuts, hemlock bark, sumac, and oak bark.
• the tannins are bisulfited by reaction with sulfite, bisulfite or formaldehyde and bisulfite, or are modified by reaction with sodium or ammonium cyanides, with sodium chloroacetate, with sulfuric acid (either sulfonation or oxidation), with nitric acid (which would involve either oxidation or nitration), etc., to produce functional group changes in the natural tannin.
• its performance is markedly improved as an aid to its action in the subject treatment.
• a preferred group of modified tannins which can be used in the subject invention is described in US. Pat. No. 2,831,022.
• water solutions of sulfurous acid salts of alkali metals or ammonia are caused to react with the insoluble portion of Western hemlock bark at increased temperatures and in the presence of an excess of sulfurous acid.
• the water-soluble alkali sulfonic acid salts which are produced are separated as water solutions from the reaction mixture.
• the water solutions can include aqueous sodium sulfite and aqueous sodium bisulfite.
• the produced compounds are sulfonic acid derivatives or sodium sulfonate derivatives of the tannins occuring in the bark.
• Such compounds have a high content of phenolic hydroxyl and are relatively nonmethoxylated.
• the disclosure of U.S. Pat. No. 2,831,022 is included in this specification by reference.
• tannins from sources other than hemlock bark which are modified as described in U.S. Pat. No. 2,831,022 also can be used with great success.
• EXAMPLE I This example shows one method which can be used to modify tannins.
• 100 grams of mangrove tannin was dissolved in 150 ml. of distilled water.
• a second solution was formed by dissolving 16.6 grams of sodium chloroacetate in 50 ml. of distilled water.
• the second solution was added slowly to the first solution as the tannin was being heated.
• the mixture of the two solutions was agitated for l hour at a temperature slightly below boiling.
• 10 ml. ofa sodium hydroxide solution was added to maintain the pH of the mixture above 8.
• the final solution could be used as one of the component inhibitors of the invention or further processed to active solid form.
• EXAMPLE II This example illustrates a second method which can be used to produce the modified tannins of the subject invention.
• 50 grams of chestnut tannin was mixed with 0.1 gram of V 0.5 ml. of ethyl silicate 40" and 1 ml. of distilled water.
• the chestnut tannin had previously been passed through an ion exchange resin to remove cations.
• the tannins can be reacted with nitric acid in a manner similar to sulfuric acid. In both cases the reaction is a nitration or sulfonation and/or oxidation reaction.
• the modification can be carried out through the use of sodium, potassium or ammonium cyanide or sodium, potassium or ammonium thiocyanate in which case the modification procedure would be carried out in a manner similar to those shown above in example I in connection with sodium chloroacetate.
• sodium chloroacetate one can use any sodium or potassium haloacetate, halopropionate or halobutyrate.
• the tannins can also be modified by the method shown in US. Pat. No. 2,831,022.
• the sulfite or bisulfite modifications shown in the patent are preferred for preparation of tannins for use in connection with this invention.
• the reaction is carried out initially at a moderate pH (5-7) whereby the bisulfite addition takes place with the oxy ring structure being split to form additional OH groups.
• the solubilizing of the product with caustic preferably is then carried out under sufficiently mild condition (pH of 8-9) so as not to cause the product to hydrolyze or to revert to its original condition.
• Potassium or ammonium sulfite or bisulfite can be substituted for sodium sulfite or bisulfite in the process.
• any natural tannin may be substituted for the hemlock tannin of US. Pat. No. 2,831,022.
• the preferred tannins are the mangrove and/or quebracho tannins.
• HCN Modified Lignosulfonate Substituent Lignin a waste product in the processing of wood during the manufacture of paper and other cellulosic products is converted into lignosulfonate in the so-called sulfite process designed to remove lignin as water-soluble derivatives.
• sulfite process designed to remove lignin as water-soluble derivatives.
• Modern chemical theorists believe that the reaction goes due to the replacement of phenolic hydroxyl groups by bisulfite as described, for example, in Organic Chemistry, Cram and Hammond, 2nd Edition, 1964, page 697.
• lignin Since the basic substance, lignin, is a wood fraction which is a noncarbohydrate polymer, the soluble product obtained by digestion with alkali bisulfite known as lignosulfonate is a mixture of polymers containing various groups.
• a further modification of the solubilized lignin which comprises reacting HCN with the lignosulfonate to produce an HCN modified lignosulfonate.
• HCN modified lignosulfonate is defined as a modification by use of HCN or its alkali metal or ammonium salt of a lignosulfonate and its normally contained wood sugars.
• the HCN'modified lignosulfonate products are extremely stable and practically irreversible, having an extremely negligible HCN release factor.
• an antifoam is described in British application No. 22,771/47, Aug. 15, 1947, and comprises an intimate mixture of an inorganic aerogel and a methyl siloxane polymer having perceptible rubbery characteristics and containing an average of from 1.75 to two carbon atoms per atom of silicon.
• a composition is commercially available under the name Dow- Corning Antifoam A, and is effective in an amount less than about 0.1 percent by weight, ordinarily at about 0.03 percent.
• a nonelectrolyte freezing point depressant for example, isopropanol, ethylene glycol, glycerol and the like. At least about 0.3 oz. of the depressant composition, having reference only to the ingredients comprising the invention, is
• compositions are ordinarily added in an amount of about 0.3-3 oz. per gallon, or about 0225-225 percent by weight of the liquid based on a liquid specific gravity of l.
• at least 0.75 oz. per gallon is added, and at least 1.0 oz. per gallon is further preferred for optimum metal protection.
• water-dispersible lignosulfonate precursors there may be utilized additionally water-soluble naphthalene sulfonates which contain one or more sulfonated naphthalene nuclei, for example, polymethylene-bisnaphthalene sulfonate in its sodium or potassium salt form, alkyl naphthalene sulfonates or the sodium or potassium salts thereof in which the alkyl group contains about one -12 carbons as described in US. Pat. No. 3,l 73,864, Freedman (Nalco).
• the HCN modified naphthalene sulfonates may be used in the same manner and proportions as the lignosulfonates when treated with HCN, NaCN, KCN or NH CN.
• wood sugars which when present provide the major increase in functionality by conversion of the sugars to sugar acids as for example by oxidation of the terminal carbon of the aldose to glycaric acid.
• preferable starting materials for HCN modification are lignosulfonates wherein the usual appreciable quantities of reducing sugars have been previously removed or reduced as by oxidation. This is especially true in utilizing the compositions of the present invention in treating admiralty metal surfaces where such sugars induce pitting but does not appear critical where the cooling water system surfaces are ferrous or carbon steel.
• the third component comprising the compositions of the invention is what is termed as a masking agent.
• This is a material which when added with the above-described chelating system, associates with the chelating or complexing agents. This reaction or absorption upon the active sites of the chelating agents tends to retard the complexing or chelating reaction of these chemicals with soluble iron species. This allows the masked organics to pass through the ionic double layer in a relatively undisturbed state. At the metal surface the organics are then demasked by release of the metal cation, allowing more effective reaction or adsorption at the surface than otherwise obtainable.
• masking agents which help to retard the complexing action of the chelating agents with soluble iron bodies are polyvalent metal ions.
• These ions are preferably selected from among zinc, nickel, cadmium, manganese, aluminum and cobalt. These metal ions, as mentioned above, react with the organic active sites whereby the entire corrosion inhibiting composition is allowed to make a close approach to the surface before being inactivated by iron species.
• Preferred sources of the above ions are water-soluble salts of these metals such as halides, acetates, nitrates, and sulfates. Most preferred are the zinc and cobalt salts in any water-soluble form.
• the portion of the three constituents making up the corrosion compositions of the invention may be varied over a wide range according to the type of water under treatment and the type of iron metal being protected.
• Preferred though are corrosion compositions which contain l0-70 parts by weight of water-dispersible tannin, 5-50 parts by weight of HCN modified lignosulfonate and l0-60 parts by weight of inorganic water-soluble metal salt.
• the most preferred compositions comprise 20-60 parts by weight of tannin, 20-50 parts by weight of HCN modified lignosulfonate and 20-60 parts by weight of inorganic salt.
• Actual plant procedure from experience gained since the filing date of Robertson US. Pat. No. 3,256,203 has shown that where solid or balled compositions are utilized, preferably about one-third additional HCN modified lignosulfonate is used as compared with the liquid formulations.
• the compounds disclosed here are useful in protecting any type of corrodible iron such as mild or carbon steel and alloys of iron.
• use amounts of the corrosion-inhibiting composition may be varied according to the severity of the corrosion problem. Generally, from about 10 parts of composition per million parts of cooling water to about 500 p.p.m. should be employed. More preferably 25-300 p.p.m. are used, with the most preferred use range being from about 30 to about p.p.m.
• One specific type of useful application involves a short term high-level initial treatment followed by continual lowlevel treatment.
• a cooling water may be treated with about 300 p.p.m. of the composition of the invention for several days followed by a 30-75 p.p.m. level treatment.
• the pH of the water itself is preferably adjusted prior to treatment. For optimum results the pH should range from about 6.0 to about 8.0.
• the corrosion compositions of the invention are useful not only in inhibiting corrosion but have a pronounced tendency to retard deposition of suspended matter upon the ,corrodible iron surface.
• Turbid waters are often used as the cooling source and generally contain suspended clay and other forms of suspended silt, calcium and iron salts, microbiological growths, alumina floc, corrosion products themselves, and other suspended solids. These contaminants are present in the natural water or are subsequently introduced by standing in presence of air or through water pretreatment processes.
• the compositions of the invention help to keep these solids from building up voluminous flocculant deposits upon the surfaces of the iron heat exchange tubes or other surfaces susceptible to such deposition. These deposits can severely reduce heat transfer coefficients in the feedwater flow to heat exchangers, unless controlled. Deposition may be prevented to a substantial degree by addition of the compositions of the invention to cooling water, preferably in the above-stated use ranges.
• sulfhydryl-containing compounds may be employed. These may be classified broadly as nitrogen-containing heterocyclic compounds, characterized by a ring nitrogen bonded to a ring carbon. To the ring carbon is attached a nonring sulfhydryl group.
• Compounds of this type are Z-mercaptothiazole, Z-mercaptobenzimidazole, Z-mercaptobenzoxazole, Zmercaptobenzothiazole and alkali metal salts of the foregoing.
• the mercaptobenzothiazole is utilized in the amount ranging from about 2.35 to about 7.8 percent by weight.
• the direct thrust of the present invention is directed to nonphosphate, nonchromate corrosion inhibitors
• the present corrosion inhibitors may be combined with other well-known inhibitors such as the sodium salt of a copolymer of ethylene and maleic anhydride, phosphates and chromates.
• both ortho and polyphosphates may be used, as well as hexavalent chromium such as sodium chromate and sodium dichromate.
• a Liquid Formulation According to the Present invention ingredient ZnSO,H,O 12.35 Rayflo C i695 Marathon B-l0-7 8.47 Soft H O 62.23
• COMPARATIVE EXAMPLE II COMPARISON OF DRY FORMULATIONS PREPARED ACCORDING TO TEACHINGS OF US. PAT. NO. 3,256,203 ROBERTSON ('203) TO SOLID COMPOUNDS PREPARED ACCORDING TO TEACHINGS OF THE PRESENT It was found that a superiority margin exists for the new products as versus the liquid and dry formulations prepared according to Robertson US. Pat. No. 3,256,203 especially in the areas of storage stability in the liquid version of comparative example 1.
• a corrosion-inhibiting composition useful in preventing corrosion of iron surfaces in contact with cooling water consisting essentially of a chelating system to complex waterdispersible iron species existing in said cooling water which chelating system comprises l070 parts by weight of a waterdispersible tannin and 5-50 parts by weight of a substance selected from cyanohydrinated lignosulfonates and cyanohydrinated naphthalene sulfonates; and 10-60 parts by weight of a masking agent to retard said complexing action of said chelating system, which comprises a water-soluble inorganic metal salt containing a multivalent metal ion selected from the group consisting of zinc, aluminum, cadmium, cobalt, nickel and manganese.
• composition of claim 1 wherein said water-dispersible tannin is a natural tannin having been modified by reaction with a material selected from the group consisting of an alkali metal sulfite, an alkali metal bisulfite, ammonium sulfite, ammonium bisulfite, an alkali metal haloacetate, an alkali metal halopropionate, an alkali metal halobutyrate, ammonium cyanide, an alkali metal cyanide, ammonium thiocyanate, alkali metal thiocyanate, nitric acid, and sulfuric acid.
• a material selected from the group consisting of an alkali metal sulfite, an alkali metal bisulfite, ammonium sulfite, ammonium bisulfite, an alkali metal haloacetate, an alkali metal halopropionate, an alkali metal halobutyrate, ammonium cyanide, an alkali metal cyanide,
• composition of claim 2 wherein said inorganic salt is zinc sulfate and said cyanohydrinated compound is cyanohydrinated lignosulfonate.
• composition of claim 1 which additionally contains about 2.35 to about 7.8 percent by weight of a compound selected from the group consisting of 2-mercaptobenzothiazole and its alkali metal salts.
• a process for inhibiting corrosion of a ferrous metal surface in contact with a corrosive cooling water medium which comprises maintaining contact of said surface with said water which additionally contains a corrosion-inhibiting composition consisting essentially of a chelating system to complex water-dispersible iron species existing in ,said cooling water which chelating system consists essentially of 10-70 parts by weight of a water-dispersible tannin, and 5-50 parts by weight of a compound selected from the group consisting of cyanohydrinated lignosulfonates and cyanohydrinated naphthalene sulfonates, and 10-60 parts by weight of a masking agent to retard said complexing action of said chelating system which consists essentially of a water-soluble inorganic metal salt containing a multivalent metal ion selected from the group consisting of zinc, cobalt, aluminum, cadmium, manganese and nickel.
• said water-dispersible tannin is a natural tannin having been modified by reaction with a material selected from the group consisting of an alkali metal sulfite, an alkali metal bisulfite, ammonium sulfite, ammonium bisulfite, alkali metal haloacetate', an alkali metal halopropionate, an alkali metal halobutyrate, ammonium cyanide, an alkali metal cyanide, ammonium thiocyanate, an alkali metal thiocyanate, nitric acid and sulfuric acid.
• a material selected from the group consisting of an alkali metal sulfite, an alkali metal bisulfite, ammonium sulfite, ammonium bisulfite, alkali metal haloacetate', an alkali metal halopropionate, an alkali metal halobutyrate, ammonium cyanide, an alkali metal cyanide, ammonium thio
• composition additionally contains about 2.35 to about 7.8 percent by weight of a compound selected from the group consisting of Z-mercaptobenzothiazole and its alkali metal salts.
• cooling water has a pH ranging from about 6.0 to 8.0 and said inhibitor composition is present in said cooling water in the amount of 10-500 parts per million.

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Citations (2)

• 1968
  • 1968-07-31 US US748916A patent/US3639263A/en not_active Expired - Lifetime
• 1969
  • 1969-06-26 GB GB32478/69A patent/GB1244123A/en not_active Expired
  • 1969-07-18 DE DE1937617A patent/DE1937617C3/de not_active Expired
  • 1969-07-28 NL NL6911545A patent/NL6911545A/xx unknown
  • 1969-07-29 ES ES369999A patent/ES369999A1/es not_active Expired
  • 1969-07-29 LU LU59182D patent/LU59182A1/xx unknown
  • 1969-07-30 FR FR6926085A patent/FR2014058A1/fr not_active Withdrawn
  • 1969-07-30 BE BE736764D patent/BE736764A/xx unknown

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