Stabilized sodium chlorite solution and a method of remediating an aqueous system using the solution

Abstract

A stable aqueous composition of sodium chlorite and a hydrated borate donor having a pH of greater than 9.0 and the weight percent ratio of sodium chlorite (reported as NaClO.sub.2) to hydrated borate donor (reported as the sum of H.sub.2O+B.sub.2O.sub.3) is less than 1.5:1 respectfully. A method of remediating an aqueous system using the stable aqueous composition.

Claims

1. A method for the remediation of an aqueous system, the method comprising: converting a composition into an aqueous solution of chlorine dioxide using a chlorine dioxide generator, wherein the composition is formed from water, sodium chlorite and a hydrated borate donor, the composition having a pH of greater than 9.0, and the weight percent ratio of sodium chlorite (NaClO.sub.2) to hydrated borate donor (H.sub.2O+B.sub.2O.sub.3) is less than 1.5:1 respectfully; applying the aqueous solution of chlorine dioxide to the aqueous system; and sustaining a chlorine dioxide concentration to obtain a Ct value sufficient to achieve remediation, wherein the Ct value is calculated by multiplying the average concentration of chlorine dioxide by the time.

2. The method according to claim 1, further comprising sustaining the concentration of chlorine dioxide using a cyclic process.

3. The method according to claim 1, further comprising sustaining the chlorine dioxide concentration using UV activation of chlorite.

4. The method according to claim 1, wherein the composition in dry form is classified as non-divisional 5.1.

5. The composition according to claim 1, wherein the weight percent ratio of sodium chlorite to hydrated borate donor based on the composition is less than 1.25:1.

6. The composition according to claim 1, wherein the weight percent ratio of sodium chlorite to hydrated borate donor based on the composition is less than 1:1.

7. The composition according to claim 1, further comprising a UV absorbent.

8. The method according to claim 1, wherein remediation achieves less than 1 CFU per ml detection using heterotrophic plate count.

9. The method according to claim 1, wherein remediation achieves greater than or equal to 3-log reduction of parasite.

10. The method according to claim 9, wherein the parasite comprises Cryptosporidium.

11. The method according to claim 9, wherein the parasite comprises Giardia.

12. The method according to claim 9, wherein the parasite comprises Ameba.

13. The method according to claim 1, wherein remediation renders the aqueous system free of algae.

14. The composition according to claim 1, wherein the pH is greater than 10.0.

15. The composition according to claim 14, wherein the pH is greater than 11.0.

16. The method according to claim 1, wherein the aqueous system comprises recreational water.

17. A method for the remediation of an aqueous system, the method comprising: applying a composition to the aqueous system, wherein the composition is formed from water, sodium chlorite, and a hydrated borate donor, the composition having a pH of greater than 9.0, and the weight percent ratio of sodium chlorite (NaClO.sub.2) to hydrated borate donor (H.sub.2O+B.sub.2O.sub.3) is less than 1.5:1 respectfully; converting the chlorite into chlorine dioxide using a cyclic process and/or UV activation of chlorite; and sustaining a chlorine dioxide concentration to obtain a Ct value sufficient to achieve remediation, wherein the Ct value is calculated by multiplying the average concentration of chlorine dioxide by the time.

18. The method according to claim 17, wherein the composition in dry form is classified as non-divisional 5.1.

19. The composition according to claim 17, wherein the weight percent ratio of sodium chlorite to hydrated borate donor based on the composition is less than 1.25:1.

20. The composition according to claim 17, wherein the weight percent ratio of sodium chlorite to hydrated borate donor based on the composition is less than 1:1.

21. The composition according to claim 17, further comprising a UV absorbent.

22. The method according to claim 17, wherein remediation achieves less than 1 CFU per ml detection using heterotrophic plate count.

23. The method according to claim 17, wherein remediation achieves greater than or equal to 3-log reduction of parasite.

24. The method according to claim 23, wherein the parasite comprises Cryptosporidium.

25. The method according to claim 23, wherein the parasite comprises Giardia.

26. The method according to claim 23, wherein the parasite comprises Ameba.

27. The method according to claim 17, wherein remediation renders the aqueous system free of algae.

28. The composition according to claim 17, wherein the pH is greater than 10.0.

29. The composition according to claim 28, wherein the pH is greater than 11.0.

30. The method according to claim 17, wherein the aqueous system comprises recreational water.

31. The method according to claim 17, wherein the aqueous systems comprises an aquatic facility.

32. The method according to claim 17, wherein the aqueous system comprises a cooling system.

33. The method according to claim 32, wherein remediation reduces legionella bacteria to less than 1 CFU per ml.

34. A stabilized aqueous sodium chlorite composition formed from: water; sodium chlorite; and a hydrated borate donor, wherein the composition having a pH of greater than 9.0, and the weight percent ratio of sodium chlorite (NaClO.sub.2) to hydrated borate donor (H.sub.2O+B.sub.2O.sub.3) is less than 1.5:1 respectfully.

35. The stabilized sodium chlorite composition according to claim 34, further comprising a UV absorbent.

36. The stabilized sodium chlorite composition according to claim 35, wherein the composition has been dried to be in a solid, dry form.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the UV absorbance spectra of Disodium Distyrylbiphenyl Disulfonate (DDBD) at a concentration of 4 mg/l in distilled H.sub.2O.

(2) FIG. 2 illustrates how the UV spectra of chlorite anion overlays that of UV absorbent DDBD. The chlorite anion is provided virtually no UV protection.

(3) FIG. 3 illustrates the presence of chlorine dioxide with UV.sub.max at 360 nm wavelength. The overwhelming portion of the ClO.sub.2 UV spectra is covered by the dome of UV protection provided by the DDBD.

(4) FIG. 4 shows the increasing concentration of chlorine dioxide resulting from the cyclic process which remains protected by the dome of UV absorbent DDBD.

(5) FIG. 5 illustrates the UV spectra of Avobenzone that effectively protects both the chlorite anion UV.sub.max of 260 nm as well as the chlorine dioxide UV.sub.max at 360 nm.

(6) FIG. 6 illustrates the cyclic process.

(7) FIG. 7 shows the average burn rates compared to the standards for packaging groups (PG) I, II, and III to the burn rates of both samples 20028-1 and 20028-2. The results clearly illustrate that both samples were classified as Non-Divisional 5.1.

DETAILED DESCRIPTION OF THE INVENTION

(8) The stabilized sodium chlorite solution comprises a chlorite donor (sodium chlorite), a borate donor and optionally a UV absorbent. I have found that oxidizers like sodium chlorite can now be safely combined with organic compounds like UV absorbents when an effective amount of borate donor is incorporated into the composition without concern of deflagration or detonation resulting from decomposition of the chlorite, which was surprising and unexpected.

(9) The stabilized aqueous sodium chlorite composition can be formed by combining water, sodium chlorite and a hydrated borate donor to achieve a desired ratio of chlorite (as NaClO.sub.2) to hydrated borate donor (reported as the sum of H.sub.2O+B.sub.2O.sub.3). The sodium chlorite and hydrated borate donor can be in solid or aqueous liquid forms prior to forming the composition. The UV absorbent can be added before or after the chlorite donor blending with the aqueous solution of hydrated borate donor.

(10) It is desirable to apply UV absorbent in sufficient concentration to inhibit the UV decomposition of the chlorine dioxide in order to achieve the desired treatment effect. The level of UV inhibition depends on the concentration of chlorite donor being applied, the intensity of the UV radiation and the like.

(11) Typically the UV absorbent is applied to the aqueous system to achieve from 0.005 to 10 ppm, more preferred 0.01 to 6 ppm and most preferred 0.02 to 4 ppm.

(12) UV absorbents comprise organic chromophores that absorb various wavelengths of light in the UV spectrum. Common examples of UV absorbents are sunscreens and optical brighteners used in laundry treatments to improve whitening of fabrics. The range of UV absorbance can vary significantly from compound to compound. Furthermore, the solubility of the compound, stability to oxidizers (e.g. chlorine and chlorine dioxide) as well as UV degradation varies from compound to compound. The selection of the UV absorbents can be altered and blended to take advantage of the differences.

(13) The use of UV absorbents is also beneficial while incorporating the cyclic process for the in-situ generation of chlorine dioxide. The cyclic process utilizes bromide ions that are activated by an oxidant such as chlorine or potassium monopersulfate to produce free bromine. The free bromine oxidizes chlorite ions producing chlorine dioxide. Chlorine dioxide inactivates microbiological organisms (i.e. Cryptosporidium). During this process the free bromine and at least some portion of the chlorine dioxide are reduced back to bromide ions and chlorite ions respectively which are recycled back to free bromine and chlorine dioxide utilizing the cyclic process. By inhibiting the UV degradation of chlorine dioxide and chlorite, the cyclic process can be carried out during daytime hours without rapid degradation of the chlorine dioxide and accelerated UV degradation of the chlorite. The cyclic process is therefore able to provide a continued and relatively consistent concentration of chlorine dioxide throughout the day.

(14) Mixtures of UV absorbents can be blended together to provide the desired UV absorbance as well as desired features already disclosed. Suitable solvents can be selected for form solutions, slurries, emulsions and the like. The consistency and solubility is limited by the formulator. Depending on the UV absorbents solubility profile, non-limiting examples of solvents include: water, methanol, ethanol, isopropyl alcohol, acetone, DMSO, mineral oil and the like. Surfactants can be used to form emulsions. Examples of surfactants include ethoxylated alcohols, ethylene and propylene block copolymers and the like.

(15) Non-limiting examples of UV absorbents include: Disodium Distyrylbiphenyl Disulfonate (DDBD), 2,4-dihydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 5-benzoyl-4-hydroxy-2-methoxy monosodium salt, 5-methyl-2-(1-methyl-ethyl)-2-aminobenzoate, 2-Ethoxyethyl-para-methoxycinnamate, para-methoxyhydroxycinnamate, Amyl-4-methoxycinnamate, Amyl para-N,N-dimethylaminobenzoate, ethyl-4-bis(2-hydroxypropyl) aminobenzoate, 4,4′-Diamino-2,2′-stilbenedisulfonic acid, 4,4′-bis(benzoxazolyl)-cis-stilbene, 2,5-bis(benzoxazol-2-yl)thiophene, tetrasodium 4,4′-bis[[4-[bis(2-hydroxyethyl)amino]-6-(4sulphonatoanilino)-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonate] and the like. Preferred UV absorbents are low toxicity optical brighteners that undergo photo-degradation when exposed to UV. Non-limiting examples of suitable optical brighteners include: Disodium Distyrylbiphenyl Disulfonate (DDBD), tetrasodium 4,4′-bis[[4-[bis(2-hydroxyethyl)amino]-6-(4sulphonatoanilino)-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonate], 4,4′-diamino-2,2′-stilbenedisulfonic acid and 4,4′-Bis[4-[bis(2-hydroxyethyl)amino]-6-anilino-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonic acid.

(16) Compositions of the invention comprise an aqueous solution of chlorite donor, borate donor and UV absorbent. It has been discovered that oxidizers like sodium chlorite can be safely combined with organic compounds like UV absorbents when an effective amount of borate donor is incorporated into the composition without concern of deflagration or detonation resulting from decomposition of the chlorite, even when the composition is dried.

(17) The borate donor is added to achieve an effective weight percent (wt %) ratio to chlorite donor. The weight percent ratio of sodium chlorite (reported as NaClO.sub.2) to hydrated borate donor (reported as the sum of H.sub.2O+B.sub.2O.sub.3) is less than 1.5:1 respectfully. The sodium chlorite content of the composition can range from 1 to 25 wt % reported as NaClO.sub.2.

(18) Non-limiting examples of borate donors include: sodium tetraborate decahydrate, sodium tetraborate pentahydrate, disodium octaborate tetrahydrate, potassium pentaborate tetrahydrate, potassium tetraborate tetrahydrate, sodium metaborate dehydrate and sodium metaborate tetrahydrate. Preferred borate donors include sodium metaborate dehydrate and sodium metaborate tetrahydrate. The preferred borate donors are hydrates that buffer the pH above 9.0 and impart a stabilized source of water if/when the composition is dried to a crystallized form.

(19) Sodium chlorite consumes 7-electrons when completely reduced during oxidation-reduction reactions. Compared to other oxyhalo compounds such as calcium hypochlorite that consumes 2-electrons, sodium chlorite is 3.5 times more efficient an oxidizer.

(20) Without being bound to a specific theory, it is believed forming an aqueous solution of sodium chlorite and hydrated borate donor results in better distribution of the hydrated borate (H.sub.2O+B.sub.2O.sub.3) throughout the crystals of sodium chlorite when the composition is dried. When nucleation and crystal formation occur during dewatering, the enhanced crystal matrix comprises combined crystals of hydrated borate and sodium chlorite crystals resulting in: isolating NaClO.sub.2 from the fuel source, release of hydrated water thereby cooling any exothermic reaction and boric oxide functioning as a flame retardant. The optimum combination of hydrated water and boric oxide (also referred to as hydrated borate) are required to ensure dried compositions comprising organic compounds and/or when the composition contacts organic compounds then dries, the processes involved does not induce spontaneous combustion.

(21) If wide spread use of sodium chlorite is to be achieved for the on-site or in-situ generation of chlorine dioxide, the composition must be sufficiently buffered to reduce the potential for release of chlorine dioxide in the event of contact with a contaminant that neutralizes the caustic used to stabilize sodium chlorite.

(22) Addition of borate donor substantially increases the buffering capacity of the sodium chlorite. In the event the sodium chlorite contacts chemical residue from cleaners etc. the excess buffer will neutralize the acidity while maintaining the stability of the sodium chlorite.

(23) With the addition of appropriate levels of hydrated borate donor to sodium chlorite, the resulting composition can be rendered safe for widespread use. The combined effects of reduced Division 5.1 classification as well as substantially increased buffering capacity provide for a composition with inherent safety built in.

(24) Non-limiting examples of UV absorbents include: Disodium Distyrylbiphenyl Disulfonate (DDBD), 2,4-dihydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 5-benzoyl-4-hydroxy-2-methoxy monosodium salt, 5-methyl-2-(1-methyl-ethyl)-2-aminobenzoate, 2-Ethoxyethyl-para-methoxycinnamate, para-methoxyhydroxycinnamate, Amyl-4-methoxycinnamate, Amyl para-N,N-dimethylaminobenzoate, ethyl-4-bis(2-hydroxypropyl) aminobenzoate, 4,4′-Diamino-2,2′-stilbenedisulfonic acid, 4 4′-bis(benzoxazolyl)-cis-stilbene, 2 5-bis(benzoxazol-2-yl)thiophene, tetrasodium 4,4′-bis[[4-[bis(2-hydroxyethyl)amino]-6-(4sulphonatoanilino)-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonate] and the like. Preferred UV absorbents are low toxicity optical brighteners that undergo photo-degradation when exposed to UV. Non-limiting examples of suitable optical brighteners include: Disodium Distyrylbiphenyl Disulfonate (DDBD), tetrasodium 4,4′-bis[[4-[bis(2-hydroxyethyl)amino]-6-(4sulphonatoanilino)-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonate], 4,4′-diamino-2,2′-stilbenedisulfonic acid and 4,4′-Bis[4-[bis(2-hydroxyethyl)amino]-6-anilino-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonic acid.

(25) Non-limiting examples of hydrated borate donors include: sodium tetraborate decahydrate, sodium tetraborate pentahydrate, disodium octaborate tetrahydrate, potassium pentaborate tetrahydrate, potassium tetraborate tetrahydrate, sodium metaborate dehydrate and sodium metaborate tetrahydrate. Preferred borate donors include sodium metaborate dehydrate, sodium metaborate tetrahydrate and disodium octaborate tetrahydrate. The preferred borate donors buffer the pH above 10.5 and impart a stabilized source of water if/when the composition is dried to a crystallized form. Additional alkali can be added to disodium octaborate tetrahydrate to elevate the pH, or blends of hydrated borate donors to achieve the desired pH.

(26) In addition to the hydrated borate donor, additional alkali such as sodium hydroxide and potassium hydroxide can be added to further elevate the pH in the event the borate donor buffers the pH below that required to stabilize the chlorite donor (i.e. approximately pH 10.5+). For example disodium octaborate tetrahydrate has a near neutral pH but provide excellent performance as a flame retardant. Addition of sodium hydroxide or potassium hydroxide to the borate solution raises the pH to enhance the stability of the sodium chlorite composition.

(27) As used herein, the term “aquatic facility” is used with reference to all structural components and equipment comprising an aqueous system used by humans for exercise, sports and/or recreation. Examples of aquatic facilities include but are not limited to: residential swimming pools, water parks, theme parks, swimming pools, spas, therapy pools, hot tubs and the like.

(28) As used herein, the term “aqueous system” describes a body of water that can be treated using the disclosed composition. Examples of aqueous systems include recreational water, cooling system exemplified by cooling towers and ponds, and waste water.

(29) As used herein, the term “cooling system” is used to describe circulating systems and once thru systems that are used to remove heat from various industrial and energy processes. Cooling systems pump water thru heat exchanges to extract heat from the process. The heat is then dissipated by passing the heated water across a cooling tower where vaporization dissipates the heat by evaporation, or returning it to a heat sink such as a large body of water exemplified by a pond, river or lake.

(30) As used herein, “recreational water” is water used by mammals (i.e. humans) for various activities such as swimming, exercise, water sports, recreation, physical therapy and diving. Examples of aqueous systems comprising recreational water include: swimming pools, hot tubs, feature pools, spas, water-park rides, therapy pools, diving wells etc.

(31) As used herein, “aqueous solution” describes the liquid portion of the composition comprised of predominantly water wherein the sodium chlorite and borate donor dissolve or slurry.

(32) As used herein, “hydrated borate donor” describes compounds that comprise hydrated water and boric oxide (reported as the sum of H.sub.2O+B.sub.2O.sub.3). Non-limiting examples of hydrated borate donors include: sodium metaborate tetrahydrate, sodium metaborate dehydrate, potassium tetraborate tetrahydrate, sodium tetraborate decahydrate, disodium octaborate tetrahydrate, hydrated sodium calcium borate hydroxide, sodium tetraborate pentahydrate and the like. The weight percent (wt %) ratio of sodium chlorite (reported as NaClO.sub.2) to hydrated borate donor (reported as the sum of H.sub.2O and B.sub.2O.sub.3) is less than 1.5:1, more preferred less than 1.25:1 and most preferred less than 1:1 respectively.

(33) As used herein, “composition in dry form” describes a solid form of the composition comprising an aqueous solution of sodium chlorite (as NaClO.sub.2) and hydrated borate donor (reported as the sum of (H.sub.2O+B.sub.2O.sub.3).

(34) As used herein the term “Ct value” is defined as the product of the average concentration of an oxidant (mg/l) and time (minutes) of exposure to the oxidant. For example, if the average chlorine dioxide concentration of ClO.sub.2 is determined to be 2.2 mg/l over a 20 minute period of time, the Ct value is calculated by multiplying the average concentration of chlorine dioxide by the time.
Ct value=2.2 mg/l>20 min
Ct value=44 min.Math.mg/l

(35) The Ct value can be targeted based on laboratory and/or field studies to achieve the desired level of inactivation. Comparatively, low Ct values (i.e. Ct=1 mg.Math.min/l) may achieve a 6-log reduction in bacteria like E. coli, while higher Ct values (i.e. Ct=90 mg.Math.min/l) may be required to reduce a parasite like Cryptosporidium by 3-log.

(36) As used herein, the term “cyclic process” relates to the recycling of substantially inert anions comprising bromide and chlorite into their oxyhalogen surrogates, exemplified by hypobromous acid and chlorine dioxide respectfully followed by reduction back to their respective anions, and where the process is repeated (FIG. 6).

(37) As used herein, the term “chlorite anion donor” and “chlorite donor” is a compound that comprises an alkali metal salt comprising chlorite anions ClO.sub.2.sup.−, chlorine dioxide, or any convenient direct or indirect source of chlorite anions. For example, chlorine dioxide can indirectly produce chlorite due to reduction in an aqueous system. Sodium chlorite directly supplies chlorite anions.

(38) As used herein, the term “chlorite anion” (also referred to as “chlorite”) comprises chlorite having the general formula ClO.sub.2.sup.−. The chlorite is the anion released when sodium chlorite is dissolved in water and converts to chlorine dioxide.

(39) As used herein, the term “recycled” means at least some portion of the recovered bromide anions and chlorite anions are regenerated to their respective oxyhalogen compounds, followed by reduction back to their respective anions, and where the process is repeated.

(40) As used herein, the term “Cryptosporidium” is used to represent any form of parasitic microbiological organism from the family of Cryptosporidium. An example of Cryptosporidium is Cryptosporidium parvum (also referred to as C. parvum, C. parvum and Cryptosporidium parvum). Other examples of Cryptosporidium include but are not limited to: C. hominis, C. canis, C. felis, C. meleagridis, and C. muris. It is to be noted that inclusion or exclusion of italic characters or print when referring to Cryptosporidium or any of its many variants does not in any way detract from its intended descriptive meaning.

(41) As used herein, the term “microbiological organisms” is used with reference to all forms of microbiological life including: parasites, bacteria, viruses, algae, fungus, and organisms encased in biofilms.

(42) As used herein, “parasites” includes any species of organism including Cryptosporidium, Giardia and Ameba that can be transferred to humans by water and cause waterborne parasitic disease in humans.

(43) As used herein, the term “inactivation” is used with reference to the ability to deactivate, kill, or destroy microbiological organisms.

(44) As used herein, “remediation” is defined as the ability to reduce the level of waterborne pathogens and/or algae to levels below that deemed acceptable for a specific application. Acceptable levels are established by various agencies exemplified by State and local Departments of Health, U.S. Environmental Protection Agency, and/or the Centers for Disease Control and Prevention. Examples of remediation for specific applications and waterborne pathogens are exemplified.

(45) In the water of a cooling system, remediation reduces legionella bacteria to less than 1 CFU per ml.

(46) In recreational water, at least one of the following is achieved: less than 1 CFU per ml detection using heterotrophic plate count; greater than or equal to a 3-log reduction of parasites, and/or rendering the aqueous system free of algae.

(47) As used herein, “Heterotrophic plate count (HPC) is also known by a number of other names, including standard plate count, total plate count, total viable count or aerobic quality count. It does not differentiate between the types of bacteria present nor does it indicate the total number of bacteria present in the water—only those capable of forming visible colonies under specified conditions on certain non-selective microbiological media. Varying the incubation temperature will favor the growth of different groups of bacteria. As it gives more meaningful information about pathogenic (disease-causing) bacteria, 35° C. (or 37° C.) is the preferred incubation temperature. HPC does not necessarily indicate microbiological safety as the bacteria isolated may not have been fecally-derived but it does give a measure of the overall general quality of the pool water, and whether the filtration and disinfection systems are operating satisfactorily. Results reported by the laboratory are traditionally expressed as colony forming units per milliliter (CFU/mL) which equates to the number of bacteria in each milliliter of the original sample of water. A HPC count of less thanl CFU/mL indicates that the disinfection system is effective. If the count is between 10 and 100 CFU/mL, a routine investigation should be conducted as soon as possible to ensure that all the management operations are functioning properly.

(48) As used herein, “CFU” (Colony Forming Units) is a unit used in microbiology to estimate the number of viable bacteria or fungal cells in a sample.

(49) As used herein “UV absorbent” describes chromophores capable of absorbing UV in the wavelengths that include at least some portion of the chlorine dioxide UV spectrum. The UV absorbent absorbs ultraviolet radiation in the range of wavelengths that include greater than 25%, preferably greater than 50% and most preferably greater than 75% of the chlorine dioxide UV absorbance spectrum. Referring to FIGS. 3 and 4, the UV absorbance spectrum of DDBD clearly encompasses the majority of chlorine dioxide UV absorbance spectrum.

(50) As used herein “effective amount of UV absorbent” is the concentration of UV absorbent needed to sufficiently inhibit UV degradation (also referred to as photo-degradation) of chlorine dioxide in order to achieve remediation.

(51) As used herein, “non-combustible” describes the dried composition when tested in accordance with the UN Manual of Tests and Criteria [49 CFR § 173.127(b)] is classified as a non-Division 5.1.

(52) As used herein, “chlorine dioxide generator” defines any system or device that can activate an aqueous solution of sodium chlorite to produce an aqueous solution of chlorine dioxide. The system or device provides for the ex-situ generation of chlorine dioxide that is then applied to the aqueous system.

(53) Code of Federal Regulations, Title 49, and the United Nations Transport of Dangerous Goods-Manual of Tests and Criteria, Fifth revised edition (2009), describes the methods for testing and determining the classification of solid materials as oxidizers (Division 5.1 materials).

(54) In accordance with regulations of the US Department of Transportation, 49 CFR § 173.127(a), an “oxidizer” (Division 5.1) is defined as a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials. A solid material is classed as a Division 5.1 material if, when tested in accordance with the UN Manual of Tests and Criteria, blends of it with cellulose have mean burning times less than or equal to the burning time of a 3:7 potassium bromate-cellulose mixture [49 CFR § 173.127(a)(l)].

(55) Solid Division 5.1 materials are assigned packing groups using the following criteria [49 CFR § 173.127(b)]: (i) Packing Group I is the sub-classification of any material which, in the 4:1 or 1:1 sample to cellulose ratio (by mass) tested exhibits a mean burning time less than the mean burning time of a 3:2 mixture, by mass, of potassium bromate and cellulose. (ii) Packing Group II is the sub-classification of any material which, in the 4:1 or 1:1 sample to cellulose ratio (by mass) tested exhibits a mean burning time less than the mean burning time of a 2:3 mixture, by mass, of potassium bromate and cellulose, and the criteria for Packing Group I are not met. (iii) Packing Group III is the sub-classification of any material which, in the 4:1 or 1:1 sample to cellulose ratio (by mass) tested exhibits a mean burning time less than the mean burning time of a 3:7 mixture, by mass, of potassium bromate and cellulose, and the criteria for Packing Groups I and II are not met.

(56) A non-Division 5.1 material is a material which, in the 4:1 or 1:1 sample to cellulose ratio (by mass) tested, does not ignite and burn, or exhibits a mean burning time greater than that of a 3:7 mixture, by mass, of potassium bromate and cellulose.

EXAMPLES

(57) Sample #1

(58) Using a heating magnetic stirrer, 2000 ml beaker and stirring rod 600 g of Technical Solution 31.25 wt % sodium chlorite (comprises 25 wt % as NaClO.sub.2) obtained from OxyChem was blended with 150 g of sodium metaborate 4 mol obtained from Rio Tinto. The solution was heated to 40° C.-45° C. and mixed until the hydrated borate was dissolved. The heated solution was mixed to sustain a large vortex. A fan was used to direct air across the surface of the beaker to assist in evaporating the water. The solution was heated and mixed until a thick slurry formed and very little vortex remained. The slurry was poured onto a stainless steel tray lined with a thick plastic liner and in a desiccating chamber to dry for 3 days.

(59) The sheet of dried composition was broken into pieces, then ground to form a fine powder that passed thru a 500 μm sieve. The powder was stored in a Nalgene bottle to form Sample #1.

(60) Sample #2

(61) Using a heating magnetic stirrer, 2000 ml beaker and stirring rod 500 g of Technical Solution 31.25 wt % sodium chlorite (comprises 25 wt % as NaClO.sub.2) obtained from OxyChem was blended with 187.5 g of sodium metaborate 4 mol obtained from Rio Tinto. Additionally 237.5 g distilled water was added. The solution was heated to 40° C.-45° C. and mixed until the hydrated borate was dissolved. The heated solution was mixed to sustain a large vortex. A fan was used to direct air across the surface of the beaker to assist in evaporating the water. The solution was heated and mixed until a thick slurry formed and very little vortex remained. The slurry was poured onto a stainless steel tray lined with a thick plastic liner and in a desiccating chamber to dry for 5 days.

(62) The sheet of dried composition was broken then ground to form a fine powder that passed thru a 500 μm sieve. The powder was stored in a Nalgene bottle to form Sample #2.

(63) The samples were sent to Stresau Laboratory located in Spooner, Wis. for Division 5.1 Solid Oxidizer Analysis. Sample #1 was designated “20028-1” and Sample #2 was designated “20028-2”.

(64) Discussion for Samples #1 and #2:

(65) The wt % ratio of sodium chlorite (reported as NaClO.sub.2) to hydrated borate (reported as the sum of B.sub.2O.sub.3+H.sub.2O) for each dried sample was determined as follows.

(66) The hydrated borate obtained from Rio Tinto comprises 34.18 wt % as B.sub.2O.sub.3 and 35.39 wt % as H.sub.2O.

(67) Sample #1 comprised 150 g as NaClO.sub.2 and 150 g (hydrate borate)×0.6957 (% as B.sub.2O.sub.3+H.sub.2O)

(68) $\begin{array}{c}\mathrm{Wt}\%\mathrm{Ratio}=150g\left(\mathrm{as}{\mathrm{NaClO}}_2\right)÷104.36g\left(\mathrm{as}{B}_2{O}_3+H_{2}O\right)\\ =1.44\left(\mathrm{as}{\mathrm{NaClO}}_2\right)\mathrm{to}1.00\left(\mathrm{as}{B}_2{O}_3+H_{2}O\right)\end{array}$

(69) Sample #2 comprised 125 g as NaClO.sub.2 and 187.5 g (hydrate borate)×0.6957 (% as B.sub.2O.sub.3+H.sub.2O)

(70) $\begin{array}{cc}\begin{array}{c}\mathrm{Wt}\%\mathrm{Ratio}=125g(\mathrm{as}{\mathrm{NaClO}}_2=130.44g{B}_2{O}_3+H_{2}O\\ =0.96\left(\mathrm{as}{\mathrm{NaClO}}_2\right)\mathrm{to}1.00\left(\mathrm{as}{B}_2{O}_3+H_{2}O\right)\end{array}& \end{array}$

(71) Results for Samples #1 and #2:

(72) FIG. 7 shows the average burn rates compared to the standards for packaging groups (PG) I, II, and III to the burn rates of both samples 20028-1 and 20028-2. The results clearly illustrate that both samples were classified as Non-Divisional 5.1.

(73) UV Activated Remediation

(74) To 49 grams distilled water 1 gram of tetrasodium 4,4′-bis[[4-[bis(2-hydroxyethyl)amino]-6-(4sulphonatoanilino)-1,3,5-triazin-2-yl]amino]stilbene-2,2′-disulphonate] was added and mixed until dissolved. Then 10 grams of sodium metaborate tetrahydrate was added mixed until dissolved. To the clear yellow solution, 40 grams of 25 wt % sodium chlorite was added and allowed to mix for 10 minutes to form a composition.

(75) 2000 ml of tap water (pH˜7.9) was added to a glass beaker into which 10 μl of composition (equivalent to 0.37 ppm as ClO.sub.2.sup.−) was added and thoroughly mixed. The beaker was placed in direct sunlight. After 70 minutes and 240 minutes samples were taken and tested for chlorine dioxide using a low range lissamine green test kit from Palin Test. The test results were 0.34 ppm as ClO.sub.2 after 70 minutes and 0.25 ppm ClO.sub.2 after 240 minutes. Calculating the Ct Value: ClO.sub.2 concentration at Time=0 min (0 mg/l) ClO.sub.2 concentration at Time=70 min (0.34 mg/l) ClO.sub.2 concentration at Time=240 min (0.25 mg/l) Calculate average ClO.sub.2 concentration at Time=70 min (0 mg/l+0.34 mg/l)÷2=0.17 mg/l Calculate average ClO.sub.2 concentration between Time=70 min & 240 min (170 min lapsed time)

(76) $\left(0.34\mathrm{mg}\text{/}l+0.25\mathrm{mg}\text{/}l\right)÷2=0.295\mathrm{mg}\text{/}l$$\begin{array}{c}\mathrm{Calculated}\mathrm{Ct}\mathrm{Value}=\left(0.17\mathrm{mg}\text{/}l\times 70\min \right)+\\ \left(0.295\mathrm{mg}\text{/}l\times 170\min \right)\\ =11.9\left(\min \times \mathrm{mg}\text{/}l\right)+50.15\left(\min \times \mathrm{mg}\text{/}l\right)\\ =62.05\left(\min \times \mathrm{mg}\text{/}l\right)\end{array}$

(77) It is to be understood that the foregoing illustrative embodiments have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the invention. Words used herein are words of description and illustration, rather than words of limitation. In addition, the advantages and objectives described herein may not be realized by each and every embodiment practicing the present invention. Further, although the invention has been described herein with reference to particular structure, steps and/or embodiments, the invention is not intended to be limited to the particulars disclosed herein. Rather, the invention extends to all functionally equivalent structures, processes and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may affect numerous modifications thereto and changes may be made without departing from the scope and spirit of the invention.