ACTIVATED FERRATE COMPOSITIONS

Abstract

Aqueous activated ferrate solutions, methods of their preparation, and methods of disinfecting organisms and oxidizing pollutants in water are provided.

Claims

1. An activated ferrate solution comprising: (a) water; (b) one or more cations selected from the group consisting of cations of alkali metals, cations of alkali earth metals, ammonium ions, and combinations thereof; (c) one or more activating agents selected from the group consisting of bicarbonate, thiosulfate, and a combination thereof; and (d) ferrate.

2. The activated ferrate solution of claim 1, wherein the concentration of ferrate is from about 0.001 wt % to about 5.0 wt %.

3. (canceled)

4. The activated ferrate solution of claim 1, wherein the activating agent is sodium bicarbonate.

5. The activated ferrate solution of claim 1, wherein the activating agent is sodium thiosulfate.

6-9. (canceled)

10. The activated ferrate solution of claim 1 further comprising a disinfectant selected from the group consisting of sodium hypochlorite, chloramine, quaternary alkylamines, and combinations thereof.

11. The activated ferrate solution of claim 10, wherein the disinfectant is sodium hypochlorite present in a concentration from about 0.001 wt % to about 5.0 wt %.

12. The activated ferrate solution of claim 1, further comprising one or more surfactants.

13. The activated ferrate solution of claim 1, wherein the activated ferrate solution has a pH from about 8.0 to about 10.

14. The activated ferrate solution of claim 1, wherein the solution is stable for a period of at least a week.

15. A method of disinfecting water or a liquid comprising contacting water or a liquid with the activated ferrate solution of claim 1.

16-20. (canceled)

21. The method of claim 15, wherein the water or a liquid contains recalcitrant organic compounds.

22. A method of disinfecting a surface comprising contacting one or more surfaces with the activated ferrate solution of claim 1.

23. The method of claim 22, wherein disinfecting the surface comprises killing one or more microorganism selected from the group consisting of Escherichia coli, Staphylococcus aureus, Shigella flexneri, Salmonella typhimurium, Clostridium difficile bacteria and spores, Rhinovirus, Norovirus, Zika virus, Ebola virus, Aspergillus, amoeba, helminthic eggs, and Histoplasma.

24. The method of claim 22, wherein disinfecting the surface comprises killing one or more antibiotic-resistant microorganisms.

25. (canceled)

26. The method of claim 22, wherein the surface is a health care surface selected from the group consisting of a surface of a hospital bed, a hospital floor, non-sterilizable medical equipment, a wall, and a tray table.

27. The method of claim 22, wherein the surface comprises a material selected from the group consisting of glass, ceramic, metal, wall paper, painted walls, and plastic.

28. A method of preparing an activated ferrate solution, comprising: (a) heating an iron-containing material selected from the group consisting of iron oxides, iron salts, and combinations thereof in the presence of potassium nitrate, thereby obtaining an iron-containing solid intermediate; and (b) adding the iron-containing solid intermediate to an aqueous solution comprising one or more activating agents selected from the group consisting of bicarbonate, thiosulfate, and a combination thereof to provide an activated ferrate solution.

29-32. (canceled)

33. The method of claim 28, wherein the activating agent is sodium bicarbonate.

34. The method of claim 28, wherein the activating agent is sodium thiosulfate.

35.-37. (canceled)

38. An activated ferrate solution prepared by the method of claim 28.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIGS. 1A and 1B demonstrate oxidation of trimethoprim (TMP) by Fe.sup.VIS.sub.2O.sub.3.sup.2 in water (1A), and by Mn.sup.VIIS.sub.2O.sub.3.sup.2 and chlorine-S.sub.2O.sub.3.sup.2(1B).

[0027] FIG. 2 shows the control experiments of trimethoprim (TMP) removal by just addition of S.sub.2O.sub.3.sup.2 and quenching reagent (NH.sub.2OH).

[0028] FIG. 3 compares oxidation of organic contaminants listed in Table 1 by Fe.sup.VI with and without S.sub.2O.sub.3.sup.2: aspartame (APT), atenolol (ATL), atrazine (ATZ), bezafibrate (BZF), caffeine (CAF), carbamazepine (CMZ), dexamethasone (DMS), diatrizoic acid (DTA), diclofenac (DCF), enrofloxacin (ENR), flumequine (FLU), ibuprofen (IBP), N,N-diethyl-3-toluamide (DEET), propranolol (PPN), sulfadimethoxine (SMX), and trimethoprim (TMP). Experimental conditions: [Contaminant].sub.0=1.0 M, [Fe.sup.VI].sub.0=100.0 M, [S.sub.2O.sub.3.sup.2].sub.0=12.5 M, pH=8.000.05, reaction time=30 s.

[0029] FIG. 4 shows removal of six representative contaminants in water by Fe.sup.VIS.sub.2O.sub.3.sup.2: carbamazepine (CMZ), diclofenac (DCF), enrofloxacin (ENR), propranolol (PPN), sulfadimethoxine (SMX), and trimethoprim (TMP). Experimental conditions: [Each contaminant].sub.0=1.0 M, [Fe.sup.VI].sub.0:[Total contaminants]=25:1, [S.sub.2O.sub.3.sup.2].sub.0:[Fe.sup.VI].sub.0=0.125, [Fe.sup.VI].sub.0=150.0 M, [S.sub.2O.sub.3.sup.2].sub.0=18.75 M, pH=8.000.05, reaction time=30 s.

[0030] FIGS. 5A-5F show effect of molar ratios of Fe.sup.VI to contaminants on the removal of six representative pharmaceuticals by Fe.sup.VIS.sub.2O.sub.3.sup.2: carbamazepine (CMZ, FIG. 5A), diclofenac (DCF, FIG. 5B), enrofloxacin (ENR, FIG. 5C), propranolol (PPN, FIG. 5D), sulfadimethoxine (SMX, FIG. 5E), and trimethoprim (TMP, FIGURE SF). Experimental conditions: [Fe.sup.VI].sub.0=100.0 M, [S.sub.2O.sub.3.sup.2].sub.0=12.5 M, pH=8.000.05, reaction time=30 s.

[0031] FIG. 6 demonstrates elimination of six pharmaceutical contaminants by Fe.sup.VIS.sub.2O.sub.3.sup.2 in real water samples obtained from Brazos River, Tex. (FIG. 6A) and Lake Bryan, Tex. (FIG. 6B). The contaminants are: carbamazepine (CMZ), diclofenac (DCF), enrofloxacin (ENR), propranolol (PPN), sulfadimethoxine (SMX), and trimethoprim (TMP). Experimental conditions: [Each contaminant].sub.0 in mixture of samples=1.0 M, [Fe.sup.VI].sub.0:[Total contaminants]=25:1, [S.sub.2O.sub.3.sup.2].sub.0:[Fe.sup.VI].sub.0=0.125, [Fe.sup.VI].sub.0=150.0 M, [S.sub.2O.sub.3.sup.2].sub.0=18.75 M, pH=8.000.05, reaction time=30 s).

[0032] FIG. 7 Removal of six representative contaminants by Fe.sup.VIS.sub.2O.sub.3.sup.2 under air or nitrogen conditions: aspartame (APT), atenolol (ATL), caffeine (CAF), diclofenac (DCF), enrofloxacin (ENR), and trimethoprim (TMP). Experimental conditions: [Contaminant].sub.0=1.0 M, [Fe.sup.VI].sub.0=100.0 M, [S.sub.2O.sub.3.sup.2].sub.0=12.5 M, pH=8.000.05, reaction time=30 s.

[0033] FIG. 8 shows EPR spectra of the reaction solutions obtained by different treatments, as shown. Experimental conditions: [TMP].sub.0=5.0 M, [Fe.sup.VI].sub.0=100.0 M, [S.sub.2O.sub.3.sup.2]:[Fe.sup.VI]=0, 1:16, 1:8 and 1:1, [DMPO]=100.0 mM, pH=8.0. The g values for each signal (left to right) were 2.0225, 2.0196, 2.01315, 2.01055, 2.00847, 2.00368, 2.00162, 1.99929, 1.99275, and 1.99003.

[0034] FIG. 9 compares trimethoprim (TMP) removal after different Fe.sup.VI treatments without and with the additions of S.sub.2O.sub.3.sup.2 and/or DMSO. Experimental conditions: [TMP].sub.0=5.0 M, [Fe.sup.VI].sub.0=100.0 M; [S.sub.2O.sub.3.sup.2].sub.0=12.5 M; [DMSO].sub.0=1.0 mM; pH=8.000.05, reaction time=30 s.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The present disclosure is directed to activated ferrate solutions and methods of their preparation and use. The inventors have discovered that a ferrate solution that is prepared by adding an iron-containing ferrate intermediate to water comprising one or more anions (e.g., anions commonly present in tap water), one or more cations (e.g., cations commonly present in tap water), and one or more carboxylic acids results in an activated ferrate solution that is an effective surface disinfectant. Accordingly, in one aspect, the present application provides an activated ferrate solution comprising:

[0036] (a) water;

[0037] (b) one or more cations selected from cations of alkali metals, cations of alkali earth metals, ammonium ions, and combinations thereof;

[0038] (c) one or more activating agents; and

[0039] (d) ferrate.

[0040] As used herein, ferrate, also referred to interchangeably as Fe.sup.VIO.sub.4.sup.2, Fe(VI)O.sub.4.sup.2, and ferrate(VI), refers to tetraoxy iron in +6 oxidation state with the chemical formula [FeO.sub.4].sup.2 or a material comprising an oxycompound of iron in an oxidation state of six.

[0041] In certain embodiments, the activated ferrate solutions have a concentration of ferrate from about 0.001 wt % to about 1.0 wt %. As used herein, the term about refers to +/5% of the recited value. In certain embodiments, the activated ferrate solutions have a concentration of Fe.sup.VIO.sub.4.sup.2 or ferrate of about 5.0 wt %.

[0042] In certain embodiments, the water is undistilled, non-deionized, tap, distilled, deionized, or DDI water. Potable or non-potable water can be used to prepare the activated ferrate solutions disclosed herein. Regular tap water, e.g., water that has not been distilled or deionized, can be used in preparation of the activated ferrate solutions provided herein, reducing the costs of preparation of the activated ferrate solutions. Alternatively, distilled or deionized water with the addition of one or more actions and one or more anions can be used.

[0043] In some instances, the one or more activating agents comprise an anion. The anions suitable for the inclusion in the activated ferrate solutions provided herein comprise carbonate, sulfate ions, and combinations thereof. The cations comprise cations of alkali metals, cations of alkali earth metals, ammonium ions, and combinations thereof.

[0044] In some embodiments, the concentration of the one or more cations is from about 0.0001 M to about 0.025 M. In certain embodiments, the concentration of the one or more anions is between from 0.0001 M to about 1.0 M.

[0045] In some embodiments, the one or more activating agents is an organic acids such as a carboxylic acid. Suitable carboxylic acids are selected from acetic acid, formic acid, citric acid, ascorbic acid, and combinations thereof.

[0046] In some embodiments, the activating agent is a carbonate, bicarbonate, thiosulfate, or sulfite. In some embodiments, the activating agent for ferrate is a carbonate. Suitable carbonates are selected from but not limited to sodium bicarbonate, potassium bicarbonate, and calcium bicarbonate. In other embodiments, the activating agent is thiosulfate.

[0047] In some embodiments, the concentration of the one or more activating agents, e.g., carbonates, is from about 0.0001 Millimolar to about 2 Millimolar. In certain embodiments, the concentration of the one or more anions is from about 0.0001 Millimolar to about 2 Millimolar.

[0048] Surprisingly, the activated ferrate solutions provided herein have a pH from about 8.0 to about 10.5 and are stable within this pH range, making them suitable for common disinfecting purposes. In some embodiments, the solutions can further comprise a disinfectant selected from sodium hypochlorite, chloramine, quaternary alkylamines, and combinations thereof. For example the disinfectant can be sodium hypochlorite present in the activated ferrate solution at a concentration of between about 0.001 wt % and about 1.0 wt %. Additionally, the activated ferrate solutions provided herein can further comprise one or more surfactants.

[0049] The activated ferrate solutions provided herein are stable for a period of at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 10 hours, at least 15 hours, at least 24 hours, at least 1 day, at least 2 days, or at least a week.

[0050] In certain embodiments, the activated ferrate solutions provided herein are activated, meaning that they are effective at disinfecting a surface.

[0051] Accordingly, in a second aspect, the present application provides methods of disinfecting a surface, comprising contacting a surface with an activated ferrate solution disclosed herein.

[0052] A used herein, disinfecting the surface comprises killing, destroying, inactivating, or otherwise disabling a microorganism such as a bacteria or a virus. As used herein, disinfecting includes killing, inactivating, or otherwise rendering microorganisms incapable of reproducing and/or infecting a host organism, such as a human.

[0053] In certain embodiments, disinfecting includes killing one to 100 million organisms. In certain embodiments, the present methods are capable of disinfecting surfaces contaminated with about 1*10.sup.1 microorganisms/cm.sup.2 to about 1*10.sup.8 microorganisms/cm.sup.2. Microorganisms that can be killed or otherwise rendered incapable of reproducing and/or infecting a host organism include bacteria, viruses, fungi, archaea, protozoa, and algae. Representative microorganisms suitable for being disinfected by the methods disclosed herein include Escherichia coli, Staphylococcus aureus, Shigella flexneri, Salmonella typhimurium, Clostridium difficile bacteria and spores, Rhinovirus, Norovirus, Zika virus, Ebola virus, Aspergillus, amoeba, helminthic eggs, and Histoplasma.

[0054] In certain embodiments, disinfecting the surface comprises killing, destroying, or otherwise rendering microorganisms incapable of reproducing and/or infecting a host organism, wherein the microorganism is an antibiotic-resistant microorganism. In certain embodiments, the antibiotic-resistant microorganism is methicillin-resistant Staphylococcus aureus (MRSA).

[0055] In certain embodiments, disinfecting the surface reduces the iron in Fe.sup.VIO.sub.4.sup.2 from Fe(VI) to Fe(III) or Fe(II). In certain embodiments, the by-products of disinfecting reactions between activated ferrate and microorganisms are non-toxic or otherwise harmless by-products, such as Fe(III).

[0056] As noted above, the methods provided herein are useful in disinfecting surfaces. Surfaces that can be disinfected include any surface having microorganisms that needs disinfection. Such surfaces include, without limitation, surfaces in homes, schools, hotels, vehicles, offices, businesses, parks, bathrooms, and the like. In certain embodiments, the surfaces are healthcare surfaces present in, for example, hospitals, nursing homes, hospices, outpatient facilities, dentists' offices, pharmacies, and the like. In certain embodiments, the health care surface is selected from a surface of a hospital bed, a hospital floor, non-sterilizable medical equipment, and a tray table.

[0057] In certain embodiments, the surface to be disinfected is porous. In certain embodiments, the surface to be disinfected is woven. In certain embodiments, the surface comprises a material selected from glass, ceramic, metal, wall paper, painted walls, and plastic.

[0058] In a third aspect, the present application provides methods of preparing an activated ferrate solution, such as disinfectant solution for disinfecting a surface comprising:

[0059] (a) heating an iron-containing material selected from iron oxides, iron salts, and combinations thereof in the presence of potassium nitrate, thereby obtaining an iron-containing solid intermediate; and

[0060] (b) adding the iron-containing solid intermediate to an aqueous solution comprising one or more activating agents

[0061] to provide a activated ferrate solution.

[0062] In certain embodiments, the activated ferrate solution is prepared by dissolving the iron-containing solid in water comprising one or more cations selected from cations of alkali metals, cations of alkali earth metals, ammonium ions, and combinations thereof; one or more anions selected from thiosulfate, carbonate, and sulfate ions; and/or one or more organic acids, intermediate immediately prior to its use as a disinfectant. In other embodiments, the solution can be stored for a period of at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 10 hours, at least 15 hours, at least 24 hours, at least 1 day, at least 2 days, or at least a week, prior to use.

[0063] In some embodiments, the activated ferrate solution comprises ferrate or Fe.sup.VIO.sub.4.sup.2 in a concentration from 0.001 wt % to about 5.0 wt %. In certain embodiments, the Fe(VI)O.sub.4.sup.2 has a concentration of about 0.25%. In some embodiments, the concentration of the one or more cations in the activated ferrate solution is from about 0.0001 M and to 1.0 M. In certain embodiments, the concentration of the one or more anions is from about 0.0001 M to about 1.0 M.

[0064] In some embodiments, the one or more organic acids is a carboxylic acid. Carboxylic acids suitable for the preparation of the activated ferrate solutions disclosed herein include acetic acid, formic acid, citric acid, ascorbic acid, and combinations thereof.

[0065] In certain embodiments, the disinfectant solution further comprises an additional disinfecting agent, for example, sodium hypochlorite. Sodium hypochlorite is useful in helping to further disinfect surfaces in synergy with ferrate. In certain embodiments, the disinfecting agent, e.g., sodium hypochlorite, has a concentration from about 0.001 wt % to about 1.0 wt %.

[0066] In certain embodiments, the disinfectant solution has a pH from about 5.0 to about 13.0. Preferably, the solutions used in the disinfecting methods disclosed herein have a pH of from about 8.0 to about 10.5.

[0067] In certain embodiments, the activated ferrate solution comprises one or more surfactants. Such surfactants are useful in cleaning surfaces that are also disinfected by the disinfectant solution.

[0068] In certain embodiments, the activated ferrate solution is an aqueous solution. The activated ferrate solution can be prepared from distilled water, un-distilled water, tap water, potable water, non-potable water, and the like. In some embodiments, the activated ferrate solution is prepared by adding the iron-containing solid intermediate described above to tap water or river water, or lake water or seawater comprising one or more activating agents. In some embodiments, the activating agent is added to the water to be decontaminated followed by the addition of the solid intermediate described above.

[0069] In a fourth aspect, provided herein are methods of removing contaminants in water, comprising contacting contaminated water with the activated ferrate solution disclosed herein.

[0070] A used herein, contaminated water comprises wastewater, polluted water, and any water containing organic contaminants such as artificial sweeteners, pesticides, pharmaceuticals, and X-ray contrast medium. As used herein, removal of contaminants comprises the chemical removal of organic contaminants by oxidation.

[0071] In a fifth aspect, the present disclosure provides methods of removing recalcitrant contaminants in water, comprising contacting contaminated water with the activated ferrate solution disclosed herein.

[0072] As used herein, recalcitrant contaminants are contaminants which have shown low oxidative reactivity with Fe.sup.VI and show incomplete removal from water despite increasing treatment time for removal, or increasing concentrations of non-activated ferrate solutions.

[0073] In certain embodiments, the ferrate solution comprises one or more fragrance compounds for providing a fragrance, e.g., to disinfected surfaces.

Examples

Preparation of Liquid Activated Ferrate Solution.

[0074] Activated ferrate was prepared by two approaches: (i) Solid ferrate intermediate was added directly added into tap water in which one or more activating agents, e.g., ions, were present creating the required conditions to activate ferrate, and (ii) Solid potassium ferrate(VI) was added into the mixture containing ferrate and target pollutant that generated in situ activated ferrate solution.

Activated Ferrate Comprising Thiosulfate

[0075] The objectives of the experiment were: (i) demonstrate the enhanced reactivity of Fe(VI) by combining it with S.sub.2O.sub.3.sup.2 for decontaminating organic pollutants in water. Sixteen organic contaminants/micropollutants were selected, which belonged to different categories (artificial sweetener, pesticides, pharmaceuticals, and X-ray contrast medium, as shown in Table 1), which have shown low reactivity with FeVI alone, (ii) exhibit tuned reactivity of FeVI to remediate rapidly the organic contamination in real water matrices (river and lake water); and (iii) elucidate reactive species that may be involved in accelerating the oxidation of pollutants in the FeVI-S.sub.2O.sub.3.sup.2 system.

[0076] To test liquid ferrate solutions using second approach, batch experiments were conducted in a series of 100 mL glass jars under constant stirring rate (400 rpm) with a magnetic stirrer. Oxidation of each micropollutant or their mixtures by Fe.sup.VI with or without S.sub.2O.sub.3.sup.2 was initiated by mixing equal solution volumes of 10 mL, and the final reaction solutions were kept at 8.000.04. The concentration of Fe.sup.VI was maintained at 100.0 M, and the ratios of [S.sub.2O.sub.3.sup.2]:[Fe.sup.VI] in the system were varied from 0 to 5.0 for aqueous removal of a target pollutant (e.g., trimethoprim, TMP (5.0 M). The optimized ratio of [S.sub.2O.sub.3.sup.2]:[Fe.sup.VI] at 1:8 (i.e., 0.125) was applied for oxidizing different pollutants in ultrapure water or real water samples (river water and lake water). After 30 s of oxidation, 20 L hydroxylamine (NH.sub.2OH solution, 1 M) was added to quench the reactions. Samples were transferred into HPLC vials and were subsequently analyzed using high performance liquid chromatography method.

[0077] Test Pollutant Preparation.

[0078] Sixteen test contaminants of high purity (>98%), Na.sub.2S.sub.2O.sub.3 and the buffer chemicals (Na.sub.2HPO.sub.4 and Na.sub.2B.sub.4O.sub.7.10H.sub.2O) were used in testing. The abbreviations, chemical structures and categories of these organic contaminants are shown in Table 1.

TABLE-US-00001 TABLE 1 Chemical structures of sixteen test organic contaminants in this study. Chemicals Abbr. Category Molecular structure Aspartame APT Artificial sweetener [00001] Atenolol ATL Beta-blocker [00002] Atrazine ATZ Herbicide [00003] Bezafibrate BZF Antilipemic agent [00004] Caffeine CAF Psychoactive drug [00005] Carbamazepine CMZ Anticonvulsant [00006] Dexamethasone DMS Corticosteroid medication [00007] Diatrizoic acid DTA X-ray contrast medium [00008] Diclofenac DCF Nonsteroidal anti- inflammatory drug [00009] Enrofloxacin ENR Fluoroquinolone antibiotic [00010] Flumequine FLU Fluoroquinolone antibiotic [00011] Ibuprofen IBP Nonsteroidal anti- inflammatory drug [00012] N,N-diethyl- 3-toluamide DEET Insect repellent [00013] Propranolol PPN Beta-blocker [00014] Sulfadimethoxine SMX Sulfonamide antibiotic [00015] Trimethoprim TMP Antibacterial drug [00016]

[0079] The stock solutions of these contaminants (10.0 M) were prepared in 10.0 mM Na.sub.2HPO.sub.4, and diluted using the same buffer solution before the removal experiments. Potassium ferrate (K.sub.2FeO.sub.4, purity >90%) was prepared using a wet chemical synthesis method. Solutions of Fe.sup.VI were prepared by adding K.sub.2FeO.sub.4 powders to 5.0 mM Na.sub.2HPO.sub.4/1.0 mM Na.sub.2B.sub.4O.sub.7.10H.sub.2O buffer solution. The concentrations of Fe.sup.VI were quantitatively measured using an UV-visible spectrometer at a wavelength of 510 nm with a molar absorption coefficient of .sub.510 nm=1150 M.sup.1 cm.sup.1: The pH value of the contaminant solutions was adjusted to 7.50 via the addition of diluted H.sub.3PO.sub.4 before mixing with Fe.sup.VI solution to achieve the desired reaction pH at 8.000.04. Methanol and phosphoric acid (85%) of high performance liquid chromatography (HPLC) grade were used in testing. 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used as the spin trap reagent for identifying the possible reactive inorganic radicals (e.g., .OH and/or SO.sub.4..sup.) in the oxidation system. All the other chemicals (e.g., hydroxylamine and permanganate) were provided from commercial sources and used without further purification. Two kinds of natural water samples were individually obtained from Brazos River (N 304233, E 96285, College Station, Tex.) and Lake Bryan (N 303330, E 962525, Bryan, Tex.). No test contaminants were detected in these waters, and the basic physico-chemical parameters are pH, 8.36, UV.sub.254, 0.071 and UV.sub.400, 0.006 for river water; and pH, 9.43, UV.sub.254, 0.202, and UV.sub.400, 0.017 for lake water. These real water samples were filtered through 0.45 m hydrophilic PVDF membrane to remove the insoluble particles before spiking the contaminant mixtures (1.0 M for each compound). 20.0 mM borate buffer was used to stabilize the solution pH of the real waters at 8.000.04. All the other solutions were prepared using the ultrapure water (resistivity >18 M cm.sup.1).

[0080] Testing.

[0081] Experiments were conducted in a series of 100 mL glass jars under constant stirring rate (400 rpm) with a magnetic stirrer. Oxidation of each contaminant or their mixtures by Fe.sup.VI with or without S.sub.2O.sub.3.sup.2 was initiated by mixing equal solution volumes of 10 mL, and the final reaction solutions were kept at 8.000.04. The concentration of Fe.sup.VI was maintained at 100.0 M, and the ratios of [S.sub.2O.sub.3.sup.2]:[Fe.sup.VI] in the system were varied from 0 to 5.0 for aqueous removal of TMP (5.0 M). The optimized ratio of [S.sub.2O.sub.3.sup.2]:[Fe.sup.VI] at 1:8 (i.e., 0.125) was used to oxidize all organic contaminants in ultrapure water or real water samples (river water and lake water). After 30 seconds of oxidation, 20.0 L NH.sub.2OH solution (1 M) was added to quench the reactions. Samples were transferred into high performance liquid chromatography (HPLC) vials, and were subsequently analyzed using the HPLC method. Similar experiments using TMP as a target contaminant were also performed by replacing Fe.sup.VI with Mn.sup.VII or chlorine under the same conditions. All experiments were carried out at room temperature, and were at least in triplicates.

[0082] To study the influence of dissolved O.sub.2 on the reaction system of Fe.sup.VI and S.sub.2O.sub.3.sup.2, TMP was first selected as the representative contaminant. The reaction solutions were purged by N.sub.2 gas and then transferred to the anaerobic glove box. The elimination experiments of TMP (5.0 M) at different ratios (0-5.0) of [S.sub.2O.sub.3.sup.2]:[Fe.sup.VI] were conducted at pH 8.0, and the reaction was quenched at 30 seconds using 20.0 L NH.sub.2OH solution (1 M). Further experiments were also performed for removal of six individual pollutants (APT, ATL, CAF, DCF, ENR, and TMP) at low concentration (1.0 M) with or without N.sub.2 purging of solutions.

[0083] The concentrations of organic contaminants during chemical oxidation by FeVI and/or S.sub.2O.sub.3.sup.2 were measured on an Ultimate 3000 Ultra high performance liquid chromatography (UHPLC) (ThermoFisher Scientific) coupled with the diode array detector. Chromatographic analysis was conducted on a RESTEK Ultra C.sub.18 analytical column (4.6 mm250 mm, particle size 5 m) at 30 C. The mobile phase was 0.05% phosphoric acid in water (A) and methanol (B). The injection volume was 10.0 L, and the other elution conditions (i.e., mobile phase compositions, flow rate and detection wavelength) are listed in Table 2.

TABLE-US-00002 TABLE 2 HPLC conditions of sixteen individual organic contaminants in this study. Mobile phase Flow rate UV.sub.max Retention Micropollutants Methanol/water (mL/min) (nm) time (min) APT 50:50 0.8 215 4.693 ATL 20:80 0.8 224 5.830 ATZ 70:30 1.0 222 6.273 BZF 70:30 1.0 228 8.050 CAF 50:50 0.8 273 4.447 CMZ 70:30 0.8 284 5.887 DMS 70:30 1.0 242 5.887 DTA 35:65 0.8 238 4.393 DCF 90:10 1.0 275 4.167 ENR 35:65 0.8 271 7.273 FLU 70:30 1.0 324 4.730 IBP 80:20 1.0 223 8.220 DEET 65:35 1.0 210 8.010 PPN 55:45 1.0 214 6.557 SMX 50:50 0.8 268 6.837 TMP 35:65 1.0 271 4.197

[0084] For the chromatographic separation of six contaminant mixtures (CMZ, DCF, ENR, PPN, SMX, and TMP), a solvent gradient method was used with flow rate of 0.8 mL/min. This method started with 35% B (0-7.5 min), followed by 35% B to 55% B (7.5-10.5 min), 55% B to 70% B (10.5-15.5 min), 70% B to 90% B (15.5-18.5 min), 90% B (18.5-25.0 min), 90% B to 35% B (25.0-25.5 min) and post-equilibration at 35% B (25.5-33.0 min).

[0085] Two inorganic reactive radicals (i.e., .OH and/or SO.sub.4..sup.), possibly produced in the oxidation system, were measured by the room-temperature electron paramagnetic resonance (EPR), which was performed at room temperature on a Bruker ELEXSYS-II E500 spectrometer (Rheinstetten, Germany) at the X-band frequency of 9.4 GHz. The reaction solutions were pre-added with DMPO (100.0 mM), and then transferred to 2 mm EPR tube for the measurements. The related operating parameters were selected: center field, 3340.0 G; sweep width, 160.0 G; sweep time, 30 seconds; attenuation, 25.0 dB; scan times, 10.

[0086] Results.

[0087] 1. The removal of TMP (5.0 M) by Fe(VI) (100.0 M) was investigated in oxygenated solutions as a function of molar ratio of S.sub.2O.sub.3.sup.2 to Fe.sup.VI ranging from 0 to 5.0 at pH 8.0. The reactions were quenched after 30 seconds. Without S.sub.2O.sub.3.sup.2, oxidation of TMP by Fe.sup.VI was about 16%, which increased rapidly to 100% at a molar ratio of 0.125 ([S.sub.2O.sub.3.sup.2]:[Fe.sup.VI]) (FIG. 1a). When only S.sub.2O.sub.3.sup.2 (12.5 M) was added into TMP-containing solution, no oxidation of TMP was seen (FIG. 2). With the increasing molar ratio from 0.125 to 1.0, a sharp decline in oxidation of TMP was observed. Further increase in the molar ratio, only about 4% elimination of TMP was found at a molar ratio of 5.0. In the experiments without oxygen in the reaction solution (for example, N.sub.2 purging), a similar oxidation of TMP by Fe.sup.VIS.sub.2O.sub.3.sup.2 system was observed (FIG. 1a). This suggests that oxygen has minimum, if any, role in carrying out oxidation of TMP by Fe.sup.VIS.sub.2O.sub.3.sup.2 mixed solution in 30 seconds.

[0088] 2. Oxidation of TMP was performed in air saturated mixed solution by replacing Fe.sup.VI with Mn.sup.VII and chlorine, two oxidants commonly used in treating water. Concentrations of oxidant and S.sub.2O.sub.3.sup.2 were kept the same as in experiments using Fe.sup.VI and quenching of the reactions was also in 30 seconds. Both Mn.sup.VII and chlorine had no enhancement due to addition of S.sub.2O.sub.3.sup.2, and only inhibition of oxidation of TMP was observed (FIG. 1b). No oxidation of TMP could be seen at a molar ratio of 5.0. This indicates that the use of S.sub.2O.sub.3.sup.2 in accelerating the oxidation of organic contaminants is limited to Fe.sup.VI but not to the other studied oxidants.

[0089] 3. Acceleration of oxidation of 16 organic contaminants by Fe.sup.VIS.sub.2O.sub.3.sup.2 system was further tested. As shown in FIG. 3, the presence of S.sub.2O.sub.3.sup.2 with Fe.sup.VI could increase the oxidation of all the contaminants in 30 seconds. Almost complete removal of typical pharmaceuticals (CMZ, DCF, PPN, SMX, TMP, and ENR) were found. Results of FIG. 3 suggest that a wide range of organic contaminants are removed rapidly by the Fe.sup.VIS.sub.2O.sub.3.sup.2. Rapid elimination of these pharmaceuticals in a mixture solution by the Fe.sup.VIS.sub.2O.sub.3.sup.2 system was also obtained (FIG. 4). This further suggests the applicability of S.sub.2O.sub.3.sup.2 in enhancing the oxidation of organic contaminants by Fe.sup.VI. For practical application, the lower ratios of Fe.sup.VI to these six contaminants were selected to further study the removal performance of this system. Compared with the partial oxidations of these compounds (25.11% for CMZ, 20.85% for DCF, 41.02% for ENR, 32.46% for PPN, 47.27% for SMX and 22.04% for TMP) at a low ratio of 25:1 for [Fe.sup.VI]:[contaminants] without S.sub.2O.sub.3.sup.2, almost complete removal was noted for six test pharmaceuticals after 30 seconds in the presence of S.sub.2O.sub.3.sup.2 (FIG. 5).

[0090] Considering the co-existence of various organic contaminants in the aquatic environment, the newly developed Fe.sup.VIS.sub.2O.sub.3.sup.2 process was tested to eliminate six pharmaceuticals (CMZ, DCF, ENR, PPN, SMX and TMP) in different water matrices. A optimum molar ratio of 0.125 ([S.sub.2O.sub.3.sup.2]:[Fe.sup.VI]) at pH 8.0 was used to remove pharmaceuticals in both river water and lake water, and the reactions were quenched in 30 seconds. The removal results are depicted in FIG. 5. Significantly, S.sub.2O.sub.3.sup.2 could enhance the removal percentages of target pharmaceuticals present in river water and lake water by Fe.sup.VI. In river water, four of the six pharmaceuticals could be removed completely (FIG. 6a). Removal of CMZ and ENR was about 80%. In lake water, removal of pharmaceuticals was less than that in river water (FIG. 6b). Eliminations of DCF, PPN, SMX, and TMP were about 80%, while removal of CMZ and ENR was about 50%. It is likely that water constituents in natural waters such as anions, cations, and dissolved organic matters are influencing the removal of the target contaminants by the oxidizing species present in mixture of Fe.sup.VI and S.sub.2O.sub.3.sup.2 solution. These results demonstrated that Fe.sup.VIS.sub.2O.sub.3.sup.2 oxidation can be adopted as an efficient and rapid remediation of natural waters.

[0091] A series of reactions that may take place when S.sub.2O.sub.3.sup.2 is added to a solution of Fe.sup.VI and contaminant. Reactions (1)-(6) result in high-valent iron species (Fe.sup.V), sulfur-centered radicals (S.sub.2O.sub.3..sup., S.sub.4O.sub.6..sup.3, .SO.sub.3.sup., .SO.sub.4.sup.) and .OH, which can possibly oxidize contaminants (Reaction 7).

HFe.sup.VIO.sub.4.sup.+S.sub.2O.sub.3.sup.2.fwdarw.HFe.sup.VO.sub.4.sup.2+S.sub.2O.sub.3..sup.Reaction 1:

HFe.sup.VIO.sub.4.sup.+2S.sub.2O.sub.3.sup.2.fwdarw.HFe.sup.VO.sub.4.sup.2+S.sub.4O.sub.6..sup.3Reaction 2:

HFe.sup.VIO.sub.4.sup.+S.sub.4O.sub.6..sup.3.fwdarw.HFe.sup.VO.sub.4.sup.2+S.sub.4O.sub.6.sup.2Reaction 3:

4HFe.sup.VIO.sub.4.sup.+3S.sub.2O.sub.3.sup.2+2OH.sup.+3H.sub.2O.fwdarw.4Fe(OH).sub.3+6SO.sub.3.sup.2Reaction 4:

HFe.sup.VIO.sub.4.sup.+SO.sub.3.sup.2.fwdarw.HFe.sup.VO.sub.4.sup.2+.SO.sub.3.sup.Reaction 5:

.SO.sub.3.sup.+O.sub.2.fwdarw..fwdarw..fwdarw..SO.sub.4.sup..fwdarw..fwdarw..fwdarw..OHReaction 6:

HFe.sup.VO.sub.4.sup.2/S.sub.2O.sub.3..sup./S.sub.4O.sub.6..sup.3/.SO.sub.3.sup./.SO.sub.4.sup./.OH+Contaminants.fwdarw.Oxidized productsReaction 7:

HFe.sup.VO.sub.4.sup.2+S.sub.2O.sub.3.sup.2+2H.sub.2O.fwdarw.Fe(OH).sub.3+S.sub.2O.sub.4.sup.2+2OH.sup.Reaction 8:

[0092] Among the radicals, .SO.sub.4.sup. and .OH radicals could be generated through oxygen (see reaction 6), which are the stronger oxidants than the other radicals such as (E.sup.0(SO.sub.4..sup./SO.sub.4.sup.2)=2.43 V and E.sup.0(.OH/OH.sup.)=2.80 V versus E.sup.0(S.sub.2O.sub.3..sup./S.sub.2O.sub.3.sup.2=1.35 V; E.sup.0(S.sub.4O.sub.6..sup.3/S.sub.4O.sub.6.sup.2)=1.06 V; E.sup.0(SO.sub.3..sup./SO.sub.3.sup.2)=0.73 V). Participation of .SO.sub.4.sup. and .OH radicals was initially explored by performing experiments under nitrogen environment (i.e., no oxygen from air). The results did not show any significant difference in enhancing the oxidation of TMP by Fe.sup.VIS.sub.2O.sub.3.sup.2 (FIG. 1a). Similar results were also observed in oxidizing other organic contaminants (i.e., no obvious difference with and without oxygen in oxidation of APT, ATL, CAF, DCF, and ENR, FIG. 7). This finding suggests that there is no role of .SO.sub.4.sup. and .OH in oxidation of TMP by Fe.sup.VIS.sub.2O.sub.3.sup.2. This finding was further confirmed by the room-temperature electron paramagnetic resonance (EPR) measurement with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin trap reagent. Compared with the EPR spectrum of Fe.sup.VI and DMPO system, no new signal was observed after introducing S.sub.2O.sub.3.sup.2 into the reaction system (FIG. 8). This indicates that .OH and/or SO.sub.4..sup. were not produced using Fe.sup.VI/S.sub.2O.sub.3.sup.2, and therefore not contributing to the enhanced oxidation of organic contaminants. Other radicals, S.sub.2O.sub.3..sup., S.sub.4O.sub.6..sup.3, and SO.sub.3..sup., seem to be mild oxidants and may not be responsible for enhancing effect of S.sub.2O.sub.3.sup.2 in the oxidation of contaminants by Fe.sup.VI.

[0093] Fe.sup.V has shown high reactivity with second-order rate constants of the reactions of Fe.sup.V with contaminants, which are three-four orders of magnitude higher than those of Fe.sup.VI. The role of Fe.sup.V on the Fe.sup.VIS.sub.2O.sub.3.sup.2-contaminant was explored by using dimethyl sulfoxide (DMSO) as the probing reagent for the high-valent iron species. DMSO is selectively oxidized by Fe.sup.V=0 and Fe.sup.IV=0 species through oxygen atom transfer to produce corresponding sulfone. Such reactions are different from the reaction pathways involved in radicals-based oxidation processes. To test the possibility of intermediate Fe.sup.V and Fe.sup.IV species in Fe.sup.VIS.sub.2O.sub.3.sup.2-TMP system, oxidation of TMP was followed by adding 1 mM DMSO in this system. Interestingly, oxidation of TMP was almost inhibited in the presence of DMSO (i.e., no difference with and without S.sub.2O.sub.3.sup.2 in decrease of TMP concentration by Fe.sup.VI) (FIG. 9). This suggests that Fe.sup.V and Fe.sup.IV species, generated in the Fe.sup.VIS.sub.2O.sub.3.sup.2-TMP solution were captured by DMSO and were not available to oxidize TMP. It should be pointed out that Fe.sup.VI has very slow reactivity with DMSO (k is about 1 M.sup.1 s.sup.1 at pH 8.0) and no significant removal of Fe.sup.VI by DMSO was expected in 30 seconds of the study (t.sub.1/2 is about 690 seconds). Because the reactivity of Fe.sup.IV is about two-orders less than Fe.sup.V, the acceleration of the oxidation of organic contaminants by Fe.sup.VIS.sub.2O.sub.3.sup.2 in the study was mainly caused by the Fe.sup.V species. At high concentrations of S.sub.2O.sub.3.sup.2, Fe.sup.V preferentially reacted with S.sub.2O.sub.3.sup.2 (Reaction 8). This reaction caused the inhibition of enhancement with increasing molar ratio to S.sub.2O.sub.3.sup.2 to Fe.sup.VI (see FIG. 1a). The inventors demonstrated hereby the establishment of Fe.sup.VIS.sub.2O.sub.3.sup.2 as a highly effective tool for rapidly removing a wide range of organic contaminants in water. This can be seen in real water matrices and provides a high potential for the application of Fe.sup.VIS.sub.2O.sub.3.sup.2 for rapid water depollution in contaminated water and wastewater treatment.

Preparation of Liquid Activated Ferrate Solution for Disinfection of Test Organism.

[0094] Activated ferrate was prepared by two approaches: (i) Solid intermediate was added directly added into tap water in which activating agents, e.g., ions that were present created the required conditions to activate ferrate, and (ii) Solid potassium ferrate(VI) was added into distilled water and sodium bicarbonate was added to activate ferrate. Addition of sodium bicarbonate to activate ferrate has not been previously described. To test liquid ferrate solutions for disinfection potential the inventors prepared stock solution of methicillin-resistant Staphylococcus aureus, Clostridium difficile spores and Escherichia coli in a concentration of 10.sup.6 using in one approach the tap water and in a second approach using distilled sterile water. Then ferrate was added to the solution in both cases. For the second approach sodium bicarbonate was added to activate the ferrate. In a third approach lake water (Belton, Tex.) was tested for disinfection using ferrate intermediate and sodium bicarbonate.

[0095] Test Organism Preparation.

[0096] Test organism's methicillin-resistant Staphylococcus aureus, Clostridium difficile spores and Escherichia coli were prepared in one approach in tap water to achieve a concentration of at least 10.sup.6 using a calibrated McFarland meter with color range of red and confirming actual colony counts using serial dilution and plating. In another approach the same test organisms were prepared using distilled sterile water with same concentration. In a third approach natural occurring lake water with unknown contaminant was used for testing. The results are as summarized below.

Results:

[0097] Summary

[0098] First approach: After making the test organism in tap water to achieve a minimum concentration of 10.sup.6, solid ferrate intermediate was added to the solution for varying contact times of 1-5 minutes. Low concentration of acetic acid was used to stop the reaction at the end of the contact time. The colonies were plated on blood agar and special media for Clostridium difficile and incubated for 24-48 hours. A 10.sup.6-log reduction for bacteria, and 10.sup.3-log reduction for spores was achieved in 1 minute.

[0099] Second approach: After making the test organism in distilled sterile water to achieve a minimum concentration of 10.sup.6 as described above, solid ferrate intermediate and thoroughly mixed. Then sodium bicarbonate was added to the solution (to activate ferrate) with varying contact times of 1-5 minutes. Low concentration of acetic acid was used to stop the reaction at the end of the contact time. The colonies were plated on blood agar and special media for Clostridium difficile and incubated for 24-48 hours. A 10.sup.6-log reduction for bacteria, and 10.sup.3-log reduction for spores was achieved in 1 minute.

[0100] Third approach: Natural occurring lake water with naturally occurring bacterial contamination from Lake Belton was tested for disinfection using ferrate. Ferrate was added to lake water along with sodium bicarbonate was added to activate ferrate. After a one-minute contact time the reaction was stopped using acetic acid. The solution was plated onto blood agar plates and incubated for 24-48 hours. Complete elimination was seen on treated water as compared to untreated controlled with an expected log reduction of at least 10.sup.3.

[0101] All of the above experiments prove that the new activation method for ferrate is effective on bacteria and spores in natural occurring water as well as potable water whether it is treated or untreated.

[0102] While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.