Stable Nitric Acid Blends And Uses Thereof

Abstract

A modified aqueous acid composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety and a sulfonic acid moiety; and a peroxide. Also disclosed are methods of using such composition.

Claims

1. A modified aqueous acid composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety and a sulfonic acid moiety; and a peroxide.

2. The modified aqueous acid composition according to claim 1, wherein the peroxide and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no more than 5:1 and no less than 1:3.

3. The composition according to claim 1, wherein said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds.

4. The composition according to claim 1, wherein said compound comprising an amine moiety and a sulfonic acid moiety is taurine derivative or taurine-related compound and is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates.

5. The composition according to claim 1, wherein said compound comprising an amine moiety and a sulfonic acid moiety is taurine.

6. The composition according to claim 1, wherein the peroxide is selected from the group consisting of: hydrogen peroxide; benzoyl peroxide; percarbonates; perborates; persulfates; and combinations thereof.

7. An aqueous composition for use in the removal of calcium oxalate scale, wherein said composition comprises: nitric acid in an amount ranging from 2 to 10 wt % of the total weight of the composition; sulfuric acid in an amount ranging from 0.5 to 10 wt % of the total weight of the composition; a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds in an amount ranging from 0.2 to 10 wt % of the total weight of the composition; and a peroxide in an amount ranging from 0.5 to 20 wt % of the total weight of the composition.

8. The composition according to claim 7 for use in the removal of calcium oxalate scale, wherein said composition comprises: nitric acid; sulfuric acid; a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine and derivatives thereof such as taurine-related compounds; and peroxide; wherein the total molar ratio of peroxide to nitric acid, sulfuric acid and sulfonic acid moiety ranges from 1:5 to 5:1.

9. The composition according to claim 7, wherein the total molar ratio of peroxide to nitric acid, sulfuric acid and sulfonic acid moiety ranges from 1:3 to 3:1.

10. The composition according to claim 7, wherein the total molar ratio of peroxide to nitric acid, sulfuric acid and sulfonic acid moiety ranges from 1:1 to 2:1.

11. The composition according to claim 7, wherein said compound comprising an amine moiety and a sulfonic acid moiety is taurine derivative or a taurine-related compound and is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates.

12. The composition according to claim 7, wherein said compound comprising an amine moiety and a sulfonic acid moiety is taurine.

13. The composition according to claim 7, wherein the peroxide is hydrogen peroxide.

14. A peroxide-containing composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine and derivatives thereof such as taurine-related compounds; a source of peroxide; water; and wherein said peroxide-containing composition has a pH of at least 1 and a peroxide content of at least 75% of the initial peroxide concentration after 45 days.

15. The peroxide-containing composition according to claim 14, wherein said composition has a pH of at least 1 and a peroxide content of at least 95% after 14 days.

16. The peroxide-containing composition according to claim 14, wherein said composition has a pH of at least 1 and a peroxide content of at least 90% after 20 days.

17. Method of removing calcium oxalate scale from a surface contaminated therewith, said method comprising: providing a surface contaminated with calcium oxalate scale; exposing said surface contaminated with calcium oxalate scale to a composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and a peroxide; wherein said exposing occurs for a period of time sufficient to remove a pre-determined amount of said calcium oxalate scale.

18. The method according to claim 17, wherein said compound comprising an amine moiety and a sulfonic acid moiety selected is taurine; a taurine derivative; or a taurine-related compound and is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates.

19. The method according to claim 17, wherein said sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 1:3.

20. The method according to claim 17, wherein the peroxide is hydrogen peroxide.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] It will be appreciated that numerous specific details have provided for a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered so that it may limit the scope of the embodiments described herein in any way, but rather as merely describing the implementation of the various embodiments described herein.

[0043] According to a preferred embodiment of the present invention, the composition is a multi-purpose aqueous acid hard surface cleaner, sanitizer, and/or disinfectant. Preferably, the compositions according to the present invention have value in the dissolution of calcium oxalate scale. According to a preferred embodiment, the composition may be applied by pouring a pre-determined amount onto a surface and subsequently, after a pre-determined period of time, removing such with a thorough rinse, or with a cloth or the like.

[0044] In the method for removing calcium oxalate scale, it is desirable to avoid the formation of a precipitate during/after treatment in the surrounding solution. In order to do so, one can typically prevent by using an aqueous solution containing anions of acid which do not form a precipitate. For example, acidic anions which can readily form a precipitate include but are not limited to sulfate ions and phosphate ions which form calcium sulfate and calcium phosphate.

[0045] According to a preferred embodiment of the present invention, the method for calcium oxalate scale removal is applied to:

scale adhered on an inner wall of an evaporator for concentrating a black liquor of a waste solution discharged from a digester in a sulfite pulp process, a chemiground pulp process or a semichemical pulp process;
scale adhered on inner walls of apparatuses contacting with a squeezed or extracted sugar syrup, a clarified sugar syrup or a concentrated sugar syrup in steps of producing a crude molasses from the squeezed or extracted syrup in sugar industry; and
scale adhered on an inner wall of an apparatus contacting molasses in a step of producing refined molasses from the crude molasses.

[0046] According to another preferred embodiment of the present invention, the method for calcium oxalate scale removal is applied to scale adhered on an inner wall of a beer fermentation vessel.

[0047] According to another preferred embodiment of the present invention, the method for calcium oxalate scale removal is applied to scale adhered on an inner wall of a fermentation vessel to prepare whisky or a distiller for a distillation of a fermented culture.

[0048] According to another preferred embodiment of the present invention, the method for calcium oxalate scale removal is applied to scale adhered on an inner wall of a fermentation vessel for a fermentation of a grape juice to prepare wine.

[0049] According to another preferred embodiment of the present invention, the method for calcium oxalate scale removal is applied to a surface selected from the group consisting of: scale adhered on an inner wall of a bleaching tower for bleaching a pulp, especially a kraft pulp in a multi-bleaching steps, such as five steps of a chlorination step, an alkali extraction step, a hypochlorite bleaching step, chlorine dioxide bleaching step and a peroxide bleaching step, especially in the hypochlorite bleaching step.

[0050] The efficiency for removing a scale of calcium oxalate is mainly depending upon a velocity for dissolving difficult-to-dissolve calcium oxalate but which may also contain other organic scales and/or residues such as fats, proteins and polysaccharides, regardless of a solubility of calcium oxalate itself.

[0051] Preferably, the composition used should not contain a material causing an environmental pollution and a precipitate in the solution by contacting with a scale of calcium oxalate and which does not corrode an inner wall of an apparatus used in food processing.

[0052] High temperatures are typically preferred when trying to remove scale from surface as the components of a composition are more reactive under such conditions. However, the temperature must also be balanced with the potential damage which can occur when exposing metal surfaces to cleaning compositions, especially if such contain acid or the like. Accordingly, it is preferably to maintain the temperature of the treatment (hence the temperature of the composition) between 20° C. to 90° C. and more preferably between 30° to 70° C., even more preferably, between 50° C. to 70° C.

[0053] In the present description, effective amounts are generally those amounts listed as the ranges or levels of ingredients in the descriptions which follow hereto. Unless otherwise stated, amounts listed in percentage (“%'s”) are in weight percent of the composition.

[0054] Water

[0055] According to a preferred embodiment of the present invention, the composition is mainly comprised of water with relatively low levels of active ingredients such as acid and peroxide.

[0056] According to a preferred embodiment deionized water is used. According to another preferred embodiment tap water is used. Preferably, the type of water can be selected from the group consisting of: reverse osmosis; deionized; distilled and tap water.

[0057] According to a preferred embodiment of the present invention, the composition advantageously further comprises at least one surface active agent. Preferably, the surface active agent is a surfactant. Preferably, the surfactant can be selected from the group consisting of: anionic; cationic; non-ionic; and amphoteric surfactants.

[0058] According to a preferred embodiment of the present invention, a small amount of additives can be incorporated for improving the cleaning performance or aesthetic qualities of the cleaner. Adjuncts for cleaning include additional surfactants, such as those described in Kirk-Othmer, Encyclopedia of Chemical Technology 3rd Ed., Volume 22, pp. 332-432 (Marcel-Dekker, 1983), which are incorporated herein by reference. Aesthetic adjuncts include fragrances, such as those available from Givaudan, IFF, Quest and others, and dyes and pigments which can be solubilized or suspended in the formulation, such as diaminoanthraquinones. The amount of these cleaning and aesthetic additives should remain low and should preferably not consist of more than 1% by weight of the total weight of the composition.

Example 1

[0059] According to a preferred embodiment of the present invention, a composition was prepared by admixing water, nitric acid, sulfuric acid, taurine and hydrogen peroxide to yield a concentration of each component as seen in Table 1. A conventional composition was similarly prepared

TABLE-US-00001 TABLE 1 Components in a conventional nitric acid composition vs a preferred embodiment of the present invention Example #1 - Preferred Component Conventional composition embodiment composition H.sub.2O 82 wt %  77 wt % HNO.sub.3  8 wt % 7.5 wt % H.sub.2SO.sub.4  2 wt % 1.8 wt % H.sub.2O.sub.2  8 wt % 7.5 wt % Taurine none 6.2 wt %

[0060] The pH of both compositions was measured and determined to be −0.04 and −0.06, for the conventional and preferred embodiment respectively.

[0061] Titration of a conventional nitric acid-H.sub.2SO.sub.4 and peroxide blend and a preferred composition of the present invention

[0062] A titration of a conventional nitric acid-H.sub.2SO.sub.4 and peroxide blend and a preferred composition of the present invention was carried out to assess the respective stability of each composition. The compositions are stored capped, but not sealed in a water bath at a constant temperature of 30° C.

[0063] To determine the concentration of H.sub.2O.sub.2 the solutions were titrated against a standardized KMnO.sub.4 solution. The titration procedure follows:

A solution with approximately 195 mL of dH.sub.2O and 5 mL of 96% H.sub.2SO.sub.4 was prepared
Approximately 0.1000 g of the composition was measured by an analytical balance and recorded
The diluted H.sub.2SO.sub.4 solution was used to quantitatively transfer the measured composition into a 250 mL Erlenmeyer flask
The solution was mixed constantly with a magnetic stir plate/stir bar during the titration
The solution was titrated using the standardized KMnO.sub.4 solution until the appearance of a persistent clear-pink for at least 1 minute.

[0064] The stability of the compositions was measured in terms of H.sub.2O.sub.2 percent yield and is summarized over a period of up to 45 days below in Table 2.

[0065] The moles of H.sub.2O.sub.2 found in the titrated sample and the moles of H.sub.2O.sub.2 used in the synthesis are used to calculate the percent yield.

TABLE-US-00002 TABLE 2 Titration results of a conventional nitric acid-H.sub.2SO.sub.4 and peroxide blend and a preferred composition of the present invention Conventional Composition Preferred embodiment Day (% yield) composition 0 103.2 105.0 7 84.6 98.6 14 74.9 95.3 20 69.3 92.1 28 61.3 89.0 45 45.7 79.0

[0066] In terms of stability, the composition according to a preferred embodiment of the present invention has shown significant superiority when compared to the conventional composition at each time interval where a measurement was taken.

[0067] Corrosion Testing

[0068] Corrosion testing was carried out using a conventional nitric acid-H.sub.2SO.sub.4 and peroxide blend and a preferred composition of the present invention. This was performed to assess the corrosiveness of both compositions.

[0069] Procedure:

[0070] The metal coupon was washed with acetone, air dried, and weighed, before being suspended in the test fluid. Each cell was placed in a preheated water bath for the specified test duration. After the exposure period, the coupon was removed, washed with water, followed by an acetone wash, air dried, and then weighed. The corrosion rate was determined from the weight loss, and the pitting index was evaluated visually at 40× magnification, and a photo of the coupon surface at 40× magnification was taken.

[0071] Results:

[0072] The corrosion test results are shown in Table 3. It was found that both the conventional composition (containing nitric acid-sulfuric acid-peroxide) and a preferred composition according to the present invention were not compatible with 1018CS or A7075 type metals. Test A indicates the composition which does not contain taurine while Test B indicates the composition which does contain taurine.

TABLE-US-00003 TABLE 3 Results of corrosion testing carried out on 316SS coupons at 55° C. for a period of 7 days at ambient pressure Temperature Duration Corrosion Rate Test Coupon ° C. ° F. (days) (mm/year) Pitting Index A V354 55 131 7 0.004 0 B V391 55 131 7 0.000 0

[0073] Scale Dissolution Testing—Fresh Compositions

[0074] Testing was carried out using a conventional nitric acid-H.sub.2SO.sub.4 and peroxide blend and a preferred composition of the present invention to assess the potency of each on the dissolution of calcium oxalate scale. Calcium oxalate scale is frequently comprised of several calcium salts such as calcium carbonate, calcium sulfite and/or other calcium salts. Since calcium oxalate is the most difficult to dissolve and frequently comprises the largest portion of the scale, the dissolution testing below was designed to solely focus on the ability of compositions to dissolve calcium oxalate.

[0075] To determine the solubility of CaO.sub.2H.sub.4.H.sub.2O approximately 2 g of CaO.sub.2H.sub.4.H.sub.2O was added to 50 mL of OXR, where the mass of CaO.sub.2H.sub.4.H.sub.2O was measured by difference. The CaO.sub.2H.sub.4.H.sub.2O—OXR mixture was stirred at 200 rpm for 4 hrs at ambient conditions. The mixture was then filtered under vacuum and dried at approximately 40° C. overnight. The filtered CaO.sub.2H.sub.4.H.sub.2O was cooled to room temperature and the filtered CaO.sub.2H.sub.4.H.sub.2O mass was measured by difference.

[0076] The solubility of CaO.sub.2H.sub.4.H.sub.2O in a conventional composition of nitric acid/sulfuric acid/peroxide was then calculated and determined to be 12.7 kg/m3 at ambient conditions.

[0077] The solubility of CaO.sub.2H.sub.4.H.sub.2O in a composition according to a preferred embodiment of the present invention was then calculated and determined to be 13.4 kg/m3 at ambient conditions.

[0078] The testing was carried out using a freshly prepared solution of the conventional composition as well as a freshly prepared solution of the composition according to a preferred embodiment of the present invention.

[0079] Further dissolution testing was carried out using aged compositions of both tested composition. The results are set out below.

[0080] Scale Dissolution Testing—Aged compositions

[0081] Additional dissolution testing was carried out using an aged solution of the conventional nitric acid-H.sub.2SO.sub.4 composition and peroxide blend and an aged solution of the preferred composition of the present invention to assess the effect of peroxide degradation on the potency of each on the dissolution of calcium oxalate scale.

[0082] Preferred compositions of the present invention provide a higher stability than the known composition, are free of phosphonic acid (and derivatives) and are capable of tempering the reaction between the composition and organic components found in the scale being treated/removed in order to prevent the formation of carbon black (or carbon black residue). Carbon black does not dissolve in water and if such were to be formed on the surface of a scale being treated it would prevent any chemical reaction from occurring and would thus force an operator to use mechanical means to remove the carbon black-coated scale. Carbon black is formed when organic matter is exposed to a strong acid which decomposes it down to carbon atoms. The compositions according to a preferred embodiment of the present prevent the degradation of organic matter down to carbon atoms as it slows down the reaction between the acids and said organic matter.

[0083] 5-Component Compositions

[0084] The inventors further tested combinations of monoethanolamine and methane sulfonic acid in acidic compositions comprising: nitric acid; sulfuric acid and peroxide.

[0085] The blends were stable with no color change and no peroxide degradation over a 24 hr period. According to a preferred embodiment of the present invention, one could substitute a compound comprising an amine moiety and a sulfonic acid moiety with a compound comprising an amine moiety and a compound comprising a sulfonic acid moiety. Preferably, the compound comprising an amine moiety is an alkanolamine, and more preferably the alkanolamine is selected from the group consisting of: monoethanolamine and diethanolamine. Preferably, said compound comprising a sulfonic acid moiety is an alkanesulfonic acid, more preferably, the alkanesulfonic acid is selected from the group consisting of: methane sulfonic acid; ethane sulfonic acid and combinations thereof.

[0086] In light of the above, according to another aspect of the present invention, there is provided a modified aqueous acid composition comprising:

nitric acid;
sulfuric acid;
a compound comprising an amine moiety;
a compound comprising sulfonic acid moiety; and
a peroxide.

[0087] Preferably, the peroxide and said compound comprising an amine moiety are present in a molar ratio of no more than 15:1, more preferably, no more than 10:1, even more preferably, no more than 9:1.

[0088] According to another aspect of the present invention, there is provided a modified aqueous acid composition comprising:

nitric acid;
sulfuric acid;
a compound comprising an amine moiety;
a compound comprising sulfonic acid moiety; and
a peroxide;
wherein sulfuric acid and said compound comprising sulfonic acid moiety are present in a molar ratio of no less than 1:3.

[0089] Preferably, said compound comprising an amine moiety is selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine.

[0090] Preferably, said compound comprising an sulfonic acid moiety is selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid.

[0091] According to a preferred embodiment of the present invention, said compound comprising an amine moiety is monoethanolamine.

[0092] According to a preferred embodiment of the present invention, said compound comprising an sulfonic acid moiety is methanesulfonic acid.

[0093] According to a preferred embodiment of the present invention, the source of peroxide is selected from the group consisting of: hydrogen peroxide; benzoyl peroxide; percarbonates; perborates; persulfates; and combinations thereof.

[0094] According to another aspect of the present invention, there is provided an aqueous composition for use in the removal of calcium oxalate scale, wherein said composition comprises:

nitric acid in an amount ranging from 2 to 10 wt % of the total weight of the composition;
sulfuric acid in an amount ranging from 0.5 to 10 wt % of the total weight of the composition; more preferably, in an amount ranging from 0.5 to 8.5 wt % of the total weight of the composition; even more preferably, in an amount ranging from 2 to 8.5 wt % of the total weight of the composition;
a compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine, in an amount ranging from 0.2 to 10 wt % of the total weight of the composition; more preferably, in an amount ranging from 0.2 to 5 wt % of the total weight of the composition;
a compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid, in an amount ranging from 0.2 to 20 wt % of the total weight of the composition; and
a peroxide in an amount ranging from 0.5 to 20 wt % of the total weight of the composition.

[0095] Preferably, the composition for use in the removal of calcium oxalate scale, wherein said composition comprises:

nitric acid;
sulfuric acid;
said compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine;
said compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid; and
wherein the total molar ratio of peroxide to nitric acid, sulfuric acid and to said compound comprising a sulfonic acid moiety ranges from 1:5 to 5:1.

[0096] Preferably, the total molar ratio of peroxide to nitric acid, sulfuric acid and sulfonic acid moiety ranges from 1:3 to 3:1.

[0097] More preferably, the total molar ratio of peroxide to nitric acid, sulfuric acid and sulfonic acid moiety ranges from 1:1 to 2:1.

[0098] According to a preferred embodiment of the present invention, said compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine.

[0099] According to a preferred embodiment of the present invention, said compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid.

[0100] According to a preferred embodiment of the present invention, the peroxide is hydrogen peroxide.

[0101] According to another aspect of the present invention, there is provided a peroxide-containing composition having a pH of at least 1 and a peroxide content of at least 75% of the initial peroxide concentration after 45 days, said composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine; a compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid; a source of peroxide; and water.

[0102] According to another aspect of the present invention, there is provided a peroxide-containing composition having a pH of at least 1 and a peroxide content of at least 95% after 14 days, said composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine; a compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid; a source of peroxide; and water.

[0103] According to another aspect of the present invention, there is provided a peroxide-containing composition having a pH of at least 1 and a peroxide content of at least 90% after 20 days, said composition comprising: nitric acid; sulfuric acid; a compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine; a compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid; a source of peroxide; and water.

[0104] According to another aspect of the present invention, there is provided a method of removing calcium oxalate scale from a surface contaminated therewith, said method comprising:

providing a surface contaminated with calcium oxalate scale;
exposing said surface contaminated with calcium oxalate scale to a composition comprising:
nitric acid;
sulfuric acid;
a compound comprising an amine moiety selected from the group consisting of: monoethanolamine; diethanolamine; and triethanolamine; a compound comprising a sulfonic acid moiety selected from the group consisting of: methanesulfonic acid; and ethanesulfonic acid; and
a peroxide;
for a period of time sufficient to remove a pre-determined amount of said scale.

[0105] It is to be understood that the invention is not limited to the embodiments disclosed which are illustratively offered and that modifications may be made without departing from the invention.