CATALYST, SYSTEM AND METHOD FOR MINERALIZATION OF ORGANIC POLLUTANTS
20250303398 ยท 2025-10-02
Inventors
Cpc classification
B01J37/0203
PERFORMING OPERATIONS; TRANSPORTING
B01J37/084
PERFORMING OPERATIONS; TRANSPORTING
C02F2103/32
CHEMISTRY; METALLURGY
B01J2531/0205
PERFORMING OPERATIONS; TRANSPORTING
B01J31/006
PERFORMING OPERATIONS; TRANSPORTING
B01J37/088
PERFORMING OPERATIONS; TRANSPORTING
B01J2231/70
PERFORMING OPERATIONS; TRANSPORTING
B01D69/145
PERFORMING OPERATIONS; TRANSPORTING
International classification
B01J37/02
PERFORMING OPERATIONS; TRANSPORTING
Abstract
Disclosed herein is a catalytic comprising a hexacyano metal compound; wherein the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, zinc, and combinations thereof; wherein the hexacyano metal compound comprises coordinatively unsaturated metal (II)NC centers for; and wherein the hexacyano metal compound is anchored onto an inorganic substrate. Also disclosed are a system including the catalytic material and a process for treating wastewater using the catalytic material.
Claims
1. A catalytic material comprising a hexacyano metal compound; wherein the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, zinc, and combinations thereof; wherein the hexacyano metal compound comprises coordinatively unsaturated metal (II)NC centers; and wherein the hexacyano metal compound is anchored onto an inorganic substrate.
2. The catalytic material of claim 1, wherein the hexacyano metal compound includes specific facets.
3. The catalytic material of claim 2, wherein the specific facets comprise dominant (400) and (220) facets.
4. The catalytic material of claim 2, wherein the hexacyano metal compound comprises cobalt hexacyanocobaltate with dominant (400) and (220) facets.
5. The catalytic material of claim 1, wherein the inorganic substrate comprises inorganic granules or porous inorganic scaffolds.
6. The catalytic material of claim 5, wherein the porous inorganic scaffold is a ceramic microfiltration membrane or a ceramic ultrafiltration membrane.
7. The catalytic material of claim 5, wherein the catalytic material is disposed within the interstitial spaces of the porous inorganic scaffold.
8. The catalytic material of claim 5, wherein the porous inorganic scaffold is a water filtration membrane.
9. The catalytic material of claim 7, wherein the interstitial spaces range in size from 1 to 500 nanometers.
10-13. (canceled)
14. A method of making a catalytic material, the method comprising the steps of: providing a solution comprising a metal salt and an organic substrate precursor; and heating the solution under pressure to form a catalytic material; wherein the metal salt comprises a metal selected from the group consisting of cobalt, iron, chromium, copper, manganese, nickel, vanadium, zinc and combinations thereof.
15-17. (canceled)
18. The method of claim 14, wherein the metal salt is cobalt nitrate and the organic precursor is glucose.
19. The method of claim 14, further comprising the steps of: contacting the solution comprising a metal salt and an organic substrate precursor with an inorganic substrate; and heating the combination of the inorganic substrate and the solution at an effective temperature and for a sufficient time to form and anchor the catalytic material onto the inorganic substrate.
20-25. (canceled)
26. An oxidation process system comprising a containerized vessel, wherein said containerized vessel comprises the catalytic material of claim 1 anchored to a porous inorganic scaffold.
27-45. (canceled)
46. An oxidation process for treating an aqueous source comprising the step of contacting an aqueous source with a peroxide precursor in the presence of a catalytic material; wherein the catalytic material comprises hexacyano metal compound anchored onto an inorganic substrate; wherein the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, zinc and combinations thereof; and wherein the hexacyano metal compound comprises coordinatively unsaturated metal (II)NC centers.
47-55. (canceled)
56. The oxidation process of claim 46, wherein the step of contacting the peroxide precursor with the aqueous solution in the presence of the catalytic material further comprises the step of breaking the peroxide bonds in the peroxide precursor; wherein the peroxide precursor is selected from the group consisting of peroxymonosulfate, peroxydisulfate, peracetic acid, percarbonic acid, percarbonate, hydrogen peroxide and combinations thereof.
57. The oxidation process of claim 56, wherein the step of breaking the peroxide bonds in the peroxide precursor produces reactive radicals selected from the group consisting of hydroxyl radicals, sulfate radicals, acetate radicals, carbonate radicals and combinations thereof.
58. The oxidation process of claim 56, wherein a residual peroxide concentration is less than 10 ppm.
59. The oxidation process of claim 46, wherein the aqueous source comprises organic pollutants.
60. The oxidation process of claim 46, wherein the aqueous source is selected from the group consisting of municipal wastewater, industrial wastewater, ground water, and surface water.
61. The oxidation process of claim 59, wherein the catalytic material degrades the organic pollutants in the aqueous sources.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The following detailed description of preferred embodiments of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings.
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DETAILED DESCRIPTION
[0066] The invention can be understood more readily by referencing to the following detailed description, examples, drawings, and claims, and their previous and following description. However, it is to be understood that this invention is not limited to the specific compositions, articles, devices, systems, and/or methods disclosed unless otherwise specified, and as such, of course, can vary. While aspects of the invention can be described and claimed in a particular statutory class, such as the composition of matter statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the invention can be described and claimed in any statutory class.
[0067] It is to be understood that the figures and descriptions of the invention have been simplified to illustrate elements that are relevant for a clear understanding of the invention, while eliminating, for the purpose of clarity, many other elements found in AOP, AOP-enabled filtration, and related system components. Those of ordinary skill in the art may recognize that other elements and/or steps are desirable and/or required in implementing the invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art.
[0068] While the invention is capable of being embodied in various forms, the description below of several embodiments is made with the understanding that the disclosure is to be considered as an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated. Headings are provided for convenience only and are not to be construed to limit the invention in any manner. Embodiments illustrated under any heading or in any portion of the disclosure may be combined with embodiments illustrated under the same or any other heading or other portion of the disclosure.
[0069] Any combination of the elements described herein in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
[0070] Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or description that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of embodiments described in the specification. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.
[0071] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.
[0072] As used herein, each of the following terms has the meaning associated with it in this section. Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
[0073] The articles a and an are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, an element means one element or more than one element.
[0074] As used herein, the terms optional or optionally mean that the subsequently described event, condition, component, or circumstance may or may not occur, and that the description includes instances where said event, condition, component, or circumstance occurs and instances where it does not.
[0075] Throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range. Further, for lists of ranges, including lists of lower preferable values and upper preferable values, unless otherwise stated, the range is intended to include the endpoints thereof, and any combination of values therein, including any minimum and any maximum values recited.
Catalytic Materials
[0076] In one aspect, the present invention relates in part to a catalytic material comprising a hexacyanometal compound; wherein the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, zinc, and combinations thereof, wherein the hexacyano metal compound comprises coordinatively unsaturated metal (II)NC centers; and wherein the hexacyano metal compound is anchored onto an inorganic substrate. In one embodiment, a metal compound is anchored to an inorganic substrate when the compound is covalently bound to the inorganic substrate. I
[0077] In some embodiments, the hexacyanometal compound effectively activates peroxides. As used herein, effective peroxide activation means breaking peroxide bonds in a peroxide molecules or peroxide precursor molecules such as peroxy-monosulfate, peroxydisulfate, peracetic acid, percarbonic acid, and hydrogen peroxide to produce reactive radicals such as hydroxyl radical, sulfate radical, acetate radical, carbonate radical and combinations therefore to induce pollutant degradation in water. As used herein, Effective peroxide activation also means that no residual peroxide exists at the end of the reaction, or that the residual peroxide concentration at the end of the reaction is less than the detection limit, or that the residual peroxide concentration at the end of the reaction is less than 10 ppm, or less than 5 ppm, or less than 3 ppm, or less than 1 ppm. In one embodiment, the effective peroxide activation produces reactive radicals selected from the group consisting of hydroxyl radicals, sulfate radicals, acetate radicals, carbonate radicals and combinations thereof. In one embodiment, a residual peroxide concentration after effective peroxide activation is less than 10 ppm. In one embodiment, the effective peroxide activation degrades organic pollutants in aqueous sources.
[0078] In some embodiments, the hexacyano metal compound includes specific facets. In one embodiment, the specific facets comprise dominant (400) and (220) facets. In one embodiment, the hexacyano metal compound comprises cobalt hexacyanocobaltate with dominant (400) and (220) facets. In one embodiment, the facet composition of the hexacyanometal compound facilitates the activation of a peroxide precursor.
[0079] In one embodiment, the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, vanadium, chromium, and zinc. Combinations of these metals are also contemplated. The hexacyano metal compound comprises a transition metal having a mixture of oxidation states. For example, the hexacyano metal compound may comprise one of a mixture of Fe.sup.II/Fe.sup.III, Co.sup.II/Co.sup.III, V.sup.III/V.sup.IV/V.sup.V, Cu.sup.I/Cu.sup.II, Cr.sup.II/Cr.sup.II/Cr.sup.IV, or Ni.sup.0/Ni.sup.I/Ni.sup.II oxidation states. In one embodiment, one or more transition metal having a specific oxidation state may be atomically-isolated. In one embodiment, one or more transiotn metals having a specific oxidation state, such as any of the oxidation states described above, may be coordinatively or oxidatively unsaturated, rendering them more reactive in catalytic processes.
[0080] In one embodiment, the hexacyano metal compound comprises cobalt (Co). In one embodiment, the hexacyanometal compound comprises a mixture of Co.sup.II and Co.sup.II. metal centers. In one embodiment, the Co.sup.II metal centers are unsaturated and/or atomically-isolated. In one embodiment, the hexacyano metal complex comprises a material having the formula Co.sup.IINCCo.sup.III. In one embodiment, the hexacyanometal compound comprises atomically-isolated Co.sup.IINC metal centers.
[0081] In one embodiment, the catalyst is disposed within interstitial space of a porous medium or a porous inorganic scaffold. Exemplary porous media or scaffolds include packed media such as polymeric scaffolds, glass/ceramic media (e.g., particles), sand, and filtration membranes such as microfiltration and ultrafiltration membranes and fiber filters In one embodiment, the porous medium has interstitial spaces which may be micrometer- to nanometer-sized. Nanometer-sized in this context, described spaces which have no single linear dimension greater than 100 nanometers (nm), or no greater than 500 nm, or no greater than 1000 nm. In one embodiment, the interstitial spaces have a minimum linear dimension between 1 nm and 1000 m. In one embodiment, the interstitial spaces range in size from 1 nm to 500 nm. In one embodiment, the interstitial spaces have a minimum linear dimension between 25 and 30 nm. In one embodiment, the inorganic substrate comprises inorganic granules or porous inorganic scaffolds. In some embodiments the size of the interstitial spaces may be used to exclude colloids, particles, microorganisms, and organic matter that are present in wastewater, thereby reducing the quantity of material that contacts the catalytic material. In one embodiment, the porous inorganic medium or scaffold comprises a water filtration membrane.
[0082] In one embodiment, the porous inorganic scaffold comprises a ceramic microfiltration membrane or a ceramic ultrafiltration membrane. In one embodiment, the ceramic micro- or ultrafiltration membrane comprises ZrO.sub.2 and TiO.sub.2. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter between 1 nm and 1000 nm. In one embodiment, ceramic micro- or ultrafiltration membrane has a pore diameter between 5 and 500 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter between 10 and 250 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter between 15 and 100 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter of at least 10 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter of at least 20 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter of no more than 1000 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter of no more than 900, 800, 700, 600, 500, 400, 300, 200, or 100 nm. In one embodiment, the ceramic micro- or ultrafiltration membrane has a pore diameter of no more than 100, 90, 80, 70, 60, 50, 40, 30, or 20 nm.
[0083] In one embodiment, the catalytic material comprises a core-shell particle material. In one embodiment, the core-shell particle material comprises a shell material displosed over the core material. In one embodiment, the core material is covalently bound to the shell material. In one embodiment, the core-shell particle material forms a spherical or semi-spherical particle. In one embodiment, the hexacyano metal compound forms the shell or the core of the core-shell particle material. In one embodiment, the hexacyano metal compound forms the shell of the core-shell particle. In one embodiment, the core-shell particle comprises a carbon core and a hexacyano metal compound shell. In one embodiment, the core is covalently bound to the shell. In one embodiment, the
[0084] In one embodiment the core-shell particle comprises a spherical or semi-spherical core with a shell material disposed over the entirety near-entirety of the core. For example, in some embodiments, the core material may be covalently bound to the porous inorganic medium or porous inorganic scaffoldin such an embodiment, the shell may be incontiguous due to the presence of the inorganic porous media. In some embodiments, the hexacyano metal compound has a layered morphology.
Methods of Making
[0085] In another aspect, the present invention relates to a method of making a catalytic material, the method comprising the steps of. providing a solution comprising a metal salt and an organic substrate precursor; and heating the solution under pressure to form a catalytic material; wherein the metal salt comprises a metal selected from the group consisting of cobalt, iron, chromium, copper, manganese, nickel, vanadium, zinc and combinations thereof.
[0086] In one embodiment, the method further comprises the step of contacting the solution comprising a metal salt and an organic substrate precursor with an inorganic substrate. In one embodiment, the inorganic substrate comprises a porous inorganic scaffold.
[0087] In one embodiment, the porous inorganic scaffold is any inorganic scaffold disclosed herein. In one embodiment, the step of heating the solution under pressure in the presence of the inorganic substrate results in the inorganic substrate becoming impregnated with the catalytic material. In one embodiment, the step of heating the solution under pressure in the presence of the inorganic substrate results in the catalytic material anchoring onto the inorganic substrate.
[0088] In one embodiment, the method further comprises the step of agitating the solution comprising the porous inorganic scaffold. In one embodiment, the step of agitating the solution comprising the porous inorganic scaffold effects penetration of the precursor solution into the pores of the porous inorganic scaffold.
[0089] In one embodiment, the metal salt comprises one or more of the following metals and oxidation states: Fe.sup.II, Fe.sup.III, Co.sup.II, Co.sup.III, V.sup.II, V, V.sup.V, Cu.sup.I, Cu.sup.III, Cr.sup.II, Cr.sup.III Cr.sup.I, Ni.sup.0, Ni.sup.I, Ni.sup.II, Zn.sup.0, Zn.sup.I, or Zn.sup.II. In one embodiment, the metal salt further comprises an anionic counterion. As would be understood by one of skill in the art, the ratio of counterion to transition metal is determined by the charge of each component so as to form a neutral compound. Exemplary anionic counterions include, but are not limited to, halide anions (e.g., F.sup., Cl.sup., Br.sup., and I.sup.), NO.sub.3.sup., ClO.sub.4.sup., OH.sup., H.sub.2PO.sub.4, HSO.sub.4.sup., SO.sub.4.sup.2, sulfonate anions (e.g., methanesulfonate, trifluoromethanesulfonate, p-toluenesulfonate, benzenesulfonate, 10-camphor sulfonate, naphthalene-2-sulfonate, naphthalene-1-sulfonic acid-5-sulfonate, ethan-1-sulfonic acid-2-sulfonate, and the like), and carboxylate anions (e.g., acetate, ethanoate, propanoate, benzoate, glycerate, lactate, tartrate, glycolate, and the like). In one embodiment, the counterion is nitrate (NO.sub.3.sup.). In one embodiment, the metal salt comprises cobalt nitrate, Co(NO.sub.3).sub.2.
[0090] In one embodiment, the solution is an aqueous solution. In one embodiment, the concentration of the metal salt in the solution is between 0.01 M and 100 M. In one embodiment, the concentration is between 0.01 M and 1.0 M. In one embodiment, the concentration is between 0.1 M and 1 M. In one embodiment, the concentration is between 0.2 M and 0.5 M. In one embodiment, the concentration of the metal salt is about 0.25 M.
[0091] Exemplary organic substrate precursors include, but are not limited to, organic materials with abundant oxygen functionality, including but not limited to a soluble carbohydrate, an alcohol, a carboxylic acid, and combinations thereof. In one embodiment, the soluble carbohydrate is selected from the group consisting of glucose, sucrose, fructose, galactose, lactose, maltose and combinations thereof. In one embodiment, the soluble carbohydrate is glucose.
[0092] In one embodiment, the metal salt is cobalt nitrate and the organic precursor is glucose.
[0093] In one embodiment, the organic substrate precursor comprises a sugar. In one embodiment, the organic substrate precursor comprises glucose.
[0094] In one embodiment, the concentration of the organic precursor in the solution is between 0.01 M and 100 M. In one embodiment, the concentration is between 0.01 M and 1.0 M. In one embodiment, the concentration is between 0.1 M and 1 M. In one embodiment, the concentration is between 0.2 M and 0.75 M. In one embodiment, the concentration of the organic precursor is about 0.55 M.
[0095] In some embodiments, the solution is heated to a temperature greater than 100 C., greater than 120 C., greater than 140 C., greater than 160 C., greater than 180 C., greater than 200 C., greater than 220 C., greater than 240 C., or greater than 260 C. In some embodiments, the solution may be heated to a temperature of about 260 C. In one embodiment, the solution is heated under a pressure of about 14, 15, or 16 psi. In some embodiments, the step of heating the aqueous solution under pressure comprises the step of subjecting the aqueous solution to an autoclave. In some embodiments, the temperature of the system may be increased gradually, such as at a rate of 1 C./min, 2 C./min, 3 C./min, 4 C./min, 5 C./min, 6 C./min, 7 C./min, 8 C./min, 9 C./min, or 10 C./min. For example, the temperature of the system may be increased at rate of between 1 and 10 C./min or about 5 C./min. In some embodiments, once a desired temperature is reached, said desired temperature may be maintained for a period of time. For example, the maximum temperature may be held for a period of 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, or 20 h. In some embodiments, the maximum temperature of about 260 C. may be maintained for a period of about 15 h.
Oxidation Process Systems
[0096] In one aspect, the present invention relates to an oxidation process system comprising a containerized vessel, said containerized vessel comprising a catalytic material anchored to a porous inorganic scaffold; wherein the catalytic material comprises a hexacyano metal compound; wherein the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, and zinc; and wherein the hexacyano metal compound comprises coordinatively unsaturated metal (II)NC centers.
[0097] In one embodiment, the containerized vessel is selected from the group consisting of a packed bed reactor, a pressurized membrane reactor, a batch reactor, a semi-batch reactor, a pulsed bed reactor, a fixed-bed reactor, and a plug flow reactor. In one embodiment, the containerized vessel includes a means for agitation selected from the group consisting of an agitator, a baffle, an impellor and combinations thereof. In one embodiment, the system is a portable self-contained unit or incorporated into a non-portable structure.
[0098] In one embodiment, the oxidation process system can be employed to mineralize organic contaminants in an aqueous solution such as wastewater or other contaminated aqueous effluent. In one embodiment, the system further comprises an aqueous source comprising organic pollutants. In one embodiment, the aqueous source is selected from the group consisting of municipal wastewater, industrial wastewater, ground water, and surface water. In one embodiment, the system degrades the organic pollutants. In one embodiment, the aqueous source further comprises a peroxide precursor. In one embodiment, the peroxide precursor is selected from the group consisting of hydrogen peroxide, peroxymonosulfate, peroxydisulfate, peracetic acid, and percarbonate.
[0099] In some embodiments, the vessel further comprises a peroxide precursor. In one embodiment, the catalytic material effects effective activation of the peroxide precursor. In one embodiment, the peroxide precursor is selected from the group consisting of hydrogen peroxide, peroxymonosulfate, peroxydisulfate, peracetic acid, and percarbonate.
[0100] The catalytic material may be used in an advanced oxidation process (AOP). In some embodiments, an AOP system comprises the catalytic material, either in the form of suspension, immobilized in various materials including medial filters and membrane, placed between an inlet and an outlet. A flow of wastewater through the system may be controlled by a valve and the rate of flow may be monitored and varied using the valve or similar mechanism. The system may further include a monitoring device located downstream of the outlet. The catalytic material may be located in a replaceable module or may be part of a multiple modular system to facilitate maintenance of the catalytic material while maintaining constant flow and remediation of the wastewater. Additionally, multiple modules may be used in series.
[0101] The AOP requires contact of the wastewater with peroxide precursors such as hydrogen peroxide, peroxymonosulfate, peroxydisulfate, peracetic acid, percarbonate, and combinations thereof in the presence of the catalyst. The flow rate of the wastewater and amount of catalyst and peroxide precursor may be determined by the desired amount of oxidation and the composition of the wastewater.
Oxidation Process Methods
[0102] The present invention further relates in part to An oxidation process for treating an aqueous source comprising the step of: contacting an aqueous source with a peroxide precursor in the presence of a catalytic material; wherein the catalytic material comprises hexacyano metal compound anchored onto an inorganic substrate; wherein the hexacyano metal compound comprises a metal selected from the group consisting of cobalt, iron, copper, manganese, nickel, zinc and combinations thereof, and wherein the hexacyano metal compound comprises coordinatively unsaturated metal (II)NC centers.
[0103] In one embodiment, the step of contacting the peroxide precursor with the aqueous solution in the presence of the catalytic material further comprises the step of breaking the peroxide bonds in the peroxide precursor; wherein the peroxide precursor is selected from the group consisting of peroxymonosulfate, peroxydisulfate, peracetic acid, percarbonic acid, percarbonate, hydrogen peroxide and combinations thereof. In one embodiment, the step of breaking the peroxide bonds in the peroxide precursor produces reactive radicals selected from the group consisting of hydroxyl radicals, sulfate radicals, acetate radicals, carbonate radicals and combinations thereof. In one embodiment, a residual peroxide concentration is less than 10 ppm.
[0104] In one embodiment, the aqueous source comprises organic pollutants. In one embodiment, the aqueous source is selected from the group consisting of municipal wastewater, industrial wastewater, ground water, and surface water. In one embodiment, the effective peroxide activation degrades the organic pollutants in the aqueous sources.
[0105] The invention is further demonstrated and exemplified in the following examples which should not be interpreted as limiting.
Experimental Examples
[0106] Advanced oxidation processes (AOPs) have been extensively sought after as alternatives to physical wastewater treatment processes due to their capability to destroy pollutants rather than merely relocating them to other media. However, avoiding oxidation byproduct formation by completely oxidizing them into the benign end product, CO.sub.2, has been an impossible goal to achieve in practice. Presented herein is an innovative catalytic membrane that efficiently activates peroxymonosulfate and mineralizes organic pollutants as polluted water passes through the pores of the membrane. A hydrothermal procedure is employed synthesize cobalt hexacyanocobaltate (CoHCC) catalysts with unsaturated, atomically-isolated Co.sup.IINC catalytic sites. Catalysts are immobilized on the pore walls of a commercial ceramic ultrafiltration membrane. The high performance of CoHCC in creating both sulfate and hydroxyl radicals as well as nanoscale confined reaction environment. The optimized catalytic membrane achieves>80% mineralization via single-pass treatment with less than a minute of reaction time for a wide variety of organic pollutants in simulated domestic and industrial wastewaters. Further highlighted are engineering options for practical application, cost effectiveness, and mechanisms behind exceptional performance based on computational simulation.
[0107] Presented herein is an innovative AOP strategy that employs a catalytic membrane to achieve not only highly efficient removal of organic pollutants but also their ultimate mineralization. The catalytic membrane consists of newly-synthesized cobalt hexacyanocobaltate (CoHCC) catalysts, a crystal resembling the Prussian blue structure consisting of Co.sup.IINCCo.sup.III (Simonov, A., et al., Nature 578, 256260 (2020)), that are immobilized on the pore surface of a ceramic ultrafiltration (UF) membrane. The catalysts produce a massive amount of mixed radicals, SO.sub.4.sup. and OH, by activating PMS (Hodges, B. C., et al., Nat. Nanotechnol. 13, 642650 (2018)). Consequently, the membrane pores create an extremely oxidative environment under nanoscale spatial confinement (Zhang, S., et al., Environ. Sci. Technol. 54, 1086810875 (2020); Chen, Y., et al., Angew. Chem. Int. Edit. 58, 8134-8138 (2019)) that allows efficient utilization of surface-generated radicals. Organic pollutants are mineralized to benign CO.sub.2, instead of forming potentially harmful oxidation byproducts, as the polluted water passes through the membrane without additional energy input. The catalytic membrane is tested with synthetic wastewaters, engineering options are examined, and cost implications are discussed in order to evaluate application potential.
[0108] A heterogeneous Fenton or Fenton-like reaction is a method to produce radicals via surface reactions that activate precursor molecules such as hydrogen peroxide and persulfate that contain peroxide bonds. Peroxymonosulfate (PMS) is a uniquely appealing precursor; it can be activated to produce both OH and sulfate (SO.sub.4.sup.) radicals which can be complementary to each other in attacking a wide range of organics and leading to mineralization. PMS is also a relatively inexpensive, easytotransport and easy to store chemical. For PMS activation, cobalt has shown the highest activity for catalyst preparation compared to other transition metals, as Co.sup.II-sites allow for an easier withdrawal of electrons from PMS together with a hemolytic cleavage of the peroxy bond to generate SO.sub.4-radicals (Ahn, et al., Applied Catalysis B: Environmental, 2019, 241, 561569). A portion of the SO.sub.4.Math..sup. radicals then generate OH in the aqueous phase. The coordination environment of cobalt affects the electronic structure which, in turn, affects the persulfate adsorption, electron transfer mechanism, and even the reaction pathway, kinetics, and products. Previous work showed that binding cobalt to carbon or nitrogen (Li, et al. Acs Nano 2016, 10, (12), 11532-11540) can facilitate CotoPMS electron transfer and therefore enhance catalyst performance. It was lately revealed that anchoring cobalt centers to pyridinic nitrogen on a carbon substrate further reduces the PMS adsorption energy and optimizes local electron property toward a more efficient Fenton-like process. (Li, et al. Acs Nano 2016, 10, (12), 11532-11540; Li, et al., J Am Chem Soc 2018, 140, (39), 12469-12475; Chu, et al., Environmental Science & Technology 2021, 55, (2), 1242-1250) Unfortunately, the production of isolated CoNC units in previous work relied on random defects of carbon substrates that not only have limited number of cobalt centers (<1 atom %) (Liu, et al., Chem Sci 2016, 7, (9), 5758-5764) but hindered electron transfer property on basal structures.
[0109] Cobalt hexacyanocobaltate (termed as CoHCC) is analogous to the Prussian blue structure with cubic framework built from Co.sup.IINCCo.sup.III sequences.(Simonov, et al., Nature 2020, 578, (7794), 256-+) The densely coordinated Co.sup.IINC units in the crystal structure made it of particular interest to be engineered to produce coordinatively unsaturated cobalt(II) sites for PMS activation. Additionally, close binding of a nanostructured catalyst to a substrate reduces the required surface energy so as to create coordinatively unsaturated metal centers either on catalyst-substrate interfaces (Fu, et al., Science 2010, 328, (5982), 1141-1144; et al., Science 2009, 325, (5948), 1670-1673) or twisted catalyst surfaces (Xi, et al., Nat Commun 2019, 10).
Catalyst Synthesis and Characterization
[0110] A hydrothermal synthesis procedure (
[0111] X-ray diffraction (XRD) analysis suggests the presence of a face-centered cubic crystal of CoHCC (Co.sub.3[Co(CN).sub.6].sub.2) with dominant (220) and (400) facets (
[0112] X-ray photoelectron spectroscopy (XPS,
[0113] Pollutant Degradation Performance. CoHCC in a batch suspension enabled extremely efficient PMS-based advanced oxidation. Bisphenol A (BPA) was examined as a target pollutant, considering its teratogenic and endocrine disrupting properties, massive environmental discharge (>1 million pounds per year) (U.S. Environmental Protection Agency. Bisphenol A Action Plan (2010), and ineffective removal by conventional wastewater processes (e.g., mean BPA concentration in the influent and effluent at 416 and 86 g L.sup.1, respectively) (Kasprzyk-Hordern, B., et al., Water Res. 43, 363-380 (2009)). The kinetics for parent BPA removal were too fast to be measured (i.e., nearly instantaneous BPA disappearance upon catalyst addition) when 0.050.5 g L.sup.1 of CoHCC particles were added along with 0.4 mM PMS, which are within typical catalyst/PMS loading range for PMS-based AOP in the literature (Table 1). The kinetics shown in
TABLE-US-00001 TABLE 1 Pollutant degradation via cobalt-based PMS activation in this study and in reported works. Pollutant/ Rate TOF PMS Rate constant with pH constant (10.sup.5 mol Ref. No. Catalyst Description (mM) SO.sub.4.sup. (M.sup.1 s.sup.1) () (min.sup.1) g.sup.1 min.sup.1) in FIG. 2d Co-HCC Co-HCC with preferred (400) 0.4 BPA (=20 M) 7.0 0.527 916 This work (0.00025 g L.sup.1) facet k.sub.SO.sub.
[0114] Both *OH and SO.sub.4.sup. were generated in this system. The addition of tert-butanol alcohol (TBA) as a OH scavenger (k.sub.TBA/OH6.010.sup.8 M.sup.1 s.sup.1) slowed down the reaction kinetics, with k.sub.obs dropping by about a half to 0.27 min.sup.1 (
[0115] The observed BPA degradation kinetics with CoHCC were much faster than benchmark PMS activation catalysts such as cobalt(II, III) oxide (CO.sub.3O.sub.4) (Anipsitakis, G. P., et al., J. Phys. Chem. B 109, 13052-13055 (2005); Chen, X. Y., et al., Appl. Catal. B-Environ. 80, 116-121 (2008); Chen, X. Y., et al., Appl. Catal. B-Environ. 80, 116-121 (2008)) and cobalt ferrite (CoFe.sub.2O.sub.4) (Ren, Y. M., et al., Appl. Catal. B-Environ. 165, 572-578 (2015); Yang, Q., et al., Appl. Catal. B-Environ. 88, 462-469 (2009); Li, J., et al., Chem. Eng. J. 348, 1012-1024 (2018)). As shown in
[0116] It is noteworthy that CoHCC outperformed Co.sup.2+ even when normalized by the amount of Co (e.g., Co.sup.2+ in
[0117] Mechanistic Insights. The coordination environment of cobalt is likely responsible for the superior performance of CoHCC compared to other Co-based materials (
[0118] To elucidate the mechanism, Density functional theory (DFT) calculations were performed for the PMS activation on the dominant terminations of CoHCC according to the XRD results (
[0119] CoHCC was compared with three other benchmark catalysts (CO.sub.3O.sub.4, CoFe.sub.2O.sub.4, and CoN.sub.4) (relevant structures in
[0120] Catalytic Membrane for Mineralization. To further improve pollutant removal performance, CoHCC was immobilized inside the nanochannels of an inorganic membrane scaffold. This nanoconfinement strategy has been particularly instrumental in enhancing surface-catalyzed advanced oxidation by maximizing the availability of both catalytic surfaces and short-lived radicals generated on the surface..sup.17 In addition, immobilizing catalysts inside membrane pores is critical to prevent catalyst release to the environment, which would be a concern when particulate catalysts are used in suspension. A ceramic UF membrane is employed here as the scaffold (Sterlitech corporation; composition=ZrO.sub.2 and TiO.sub.2; pore diameter 20 nm; molecular weight cutoff=400 kDa, estimated by the polyethylene glycol retention method) (Howe, K. J. & Clark, M. M. Environ. Sci. Technol. 36, 3571-3576 (2002)). After in-situ growth, catalysts were deposited alongside the network of membrane channels (
[0121] The removal of BPA was measured as the water containing BPA and PMS was passed through the membrane. Note that each data point shown in
[0122] The CoHCC loaded membrane could not only oxidize BPA (i.e., parent compound oxidation leading to various oxidation byproducts), but also mineralize BPA to CO.sub.2. The catalytic membrane achieved 80% TOC removal (initial TOC 108 mg-C L.sup.1 from 0.6 mM BPA) by lowering the flux down to 20 LMH, equivalent to a reaction time of 104 s (
[0123] Application potential and engineering consideration. We obtained even higher TOC removal by placing two membranes in series, while keeping the same water flux at 20 LMH. In this configuration, TOC removal reached up to 9496% for water containing concentrated BPA, attaining near complete mineralization. TOC removal of NOM-containing water also reached up to 8589% (
[0124] The CoHCC membrane can be applied to a wide range of water types including simulated wastewater from select industries (chemical, hospital, paper, and food), secondary effluent of municipal wastewater treatment plant, as well as reverse osmosis concentrate (ROC) from municipal wastewater reclamation. These waters were prepared to contain most typical inorganic constituents (Tables 2, 3, and 4) as well as dominant organic contaminants that constitute the target TOC (90-110 mg-C L.sup.1), which represent pollutants that are difficult to remove by traditional biological, physical, and chemical processes. Using two catalytic membranes in series at a flux of 10 LMH, we achieved over 80% TOC removal for industrial wastewaters and over 70% TOC removal for municipal and ROC wastewaters (
TABLE-US-00002 TABLE 2 Top wastewater pollutants of food, paper, chemical, and hospital industries (reported in lbs)..sup.a Food Paper Chemical Health Services Chloride Sulfate Chloride Ammonia (1001 mil) (240 mil) (75,900 mil) (7 mil) Ammonia Chloride Sulfate Phosphorus (203 mil) (17 mil) (429 mil) (48,000) Potassium Ammonia Fluoride Iron (138 mil) (7 mil) (10 mil) (40,000) Sulfate Phosphorus Ammonia Chloride (75 mil) (3 mil) (6 mil) (20,000) Sodium Aluminum Phosphorus Nitrate (32 mil) (406,000) (5 mil) (1100) Bicarbonate Nitrate Aluminum Bromide (28 mil) (148,000) (4 mil) (129) Phosphorus Iron Sodium Zinc (12 mil) (127,000) (3 mil) (110) Nitrate Sulfite Nitrate Copper (5 mil) (73,000) (2 mil) (36) Magnesium Zinc Iron Aluminum (4 mil) (65,000) (1 mil) (20) Iron Magnesium Bicarbonate Manganese (269,000) (32,000) (401,000) (8) .sup.aMost abundant pollutants in 2020 for select manufacturing industries. All data was compiled from the EPA Water Pollutant Loading Tool database (last accessed Nov. 18, 2021). Industries were classified by their Standard Industrial Classification code (20-Food, 26-Paper, 28-Chemical, 80-Health services). Note that mil = million. Only pollutants that are clearly described were considered for selection (see Excel file in the Supporting Information for the full extended list). Thus, descriptors that do not specify a particular species (i.e., COD, BOD, TDS) are not included. Note the relative dominance of chloride and sulfate in these industrial effluents.
TABLE-US-00003 TABLE 3 Top wastewater pollutants of municipal and ROC wastewater (reported in lbs)..sup.a Municipal ROC Ammonia (4051 mil) Bicarbonate Chloride (1343 mil) Chloride Sulfate (808 mil) Sulfate Phosphorus (304 mil) Nitrate Bicarbonate (240 mil) Bromide Sodium (218 mil) Sodium Silica (107 mil) Calcium Nitrate (77 mil) Magnesium Magnesium (32 mil) Ammonia Potassium (16 mil) Phosphate Potassium Iron .sup.aMost abundant pollutants in 2020 for municipal and reverse osmosis concentrate (ROC) wastewater. Data for municipal wastewater was compiled from the EPA Water Pollutant Loading Tool database (last accessed Nov. 18, 2021). Note that mil = million.
TABLE-US-00004 TABLE 4 Details of the as-synthesized wastewater samples for testing..sup.a Municipal Food Paper (mg (mg (mg Constituent L.sup.1) Constituent L.sup.1) Constituent L.sup.1) NaCl 165 NaCl 82 NaCl 66 Na.sub.2SO.sub.4 80 Na.sub.2SO.sub.4 121 Na.sub.2SO.sub.4 630 NaHCO.sub.3 289 NaHCO.sub.3 413 Na.sub.2HPO.sub.4 0.5 Na.sub.2HPO.sub.4 1.4 Na.sub.2HPO.sub.4 1.1 NH.sub.4Cl 2.0 NH.sub.4Cl 0.65 NH.sub.4Cl 1.5 Na.sub.2SO.sub.3 7.0 NaNO.sub.3 6.2 NaNO.sub.3 1.2 ZnCl.sub.2 0.5 MgSO.sub.4 30.8 KCl 317 FeCl.sub.2 1.4 KCl 14.4 MgCl.sub.2 51 AlNO.sub.3 5.6 Silica (SiO.sub.2) 1.0 FeCl.sub.2 1.1 Chemical Health Services ROC (mg (mg (mg Constituent L.sup.1) Constituent L.sup.1) Constituent L.sup.1) NaCl 150 NaCl 400 NaCl 1053 Na.sub.2SO.sub.4 135 Na.sub.2HPO.sub.4 2.0 Na.sub.2SO.sub.4 500 NaHCO.sub.3 410 NH.sub.4Cl 1.7 NaHCO.sub.3 1300 Na.sub.2HPO.sub.4 1.4 NaNO.sub.3 17 Na.sub.2HPO.sub.4 18 NH.sub.4Cl 1.4 NaBr 0.5 NH.sub.4HCO.sub.3 262 NaF 3.6 FeCl.sub.2 1.0 NaBr 2.7 AlNO.sub.3 5.6 MnCl.sub.2 0.5 NaNO.sub.3 18 FeCl.sub.2 2.2 CuCl.sub.2 0.5 KCl 151 ZnCl.sub.2 0.5 MgCl.sub.2 131 AlCl.sub.3 0.5 CaCl.sub.2 358 FeCl.sub.2 1.2 .sup.aThe solutions were chosen to represent model wastewaters to evaluate the effects of common industrial effluent species on membrane performance. For each constituent, the median concentrations from the DMR analyses and the ROC literature review were employed as reference values to predict which are more likely to be present at higher levels. Phosphate was used as a proxy species for phosphorus in the synthesized ROC wastewater. NaH.sub.2PO.sub.4 and NaHCO.sub.3 were chosen to represent phosphate and bicarbonate as they are expected to be prevalent at the reported pH levels of these effluents in the synthesized Chemical and Health Services wastewaters.
[0125] The high efficiency with ROC is particularly noteworthy, since ROC contains high concentrations of Cl.sup. (640 mg L.sup.1) and HCO.sub.3.sup. (950 mg L.sup.1) that can quench radicals (k.sub.cl/SO.sub.
[0126] The CoHCC membrane maintained its performance over 3 weeks without deactivation (
[0127] The energy consumption was estimated using electrical energy per order (EEO), a common parameter used to gauge energy efficiency of AOPs, defined by the International Union of Pure and Applied Chemistry (IUPAC). The EEO for AOP driven by the catalytic membrane disclosed herein was compared with EEOs reported for various AOPs employing different activation strategies (see below for calculation details). As shown in
TABLE-US-00005 TABLE 5 Mineralization efficiency by the membrane disclosed herein and other AOP systems with photo- and/or electro-energies Starting TOC EEO TOC TOC removal (kWh/ Radical (mgC removal Time (mgC m.sup.3/ source Catalyst Reaction system description pH Organic L.sup.1) (%) (min) L.sup.1min.sup.1) order) Ref. PMS Co-HCC Membrane-confined AOP 7 BPA 100 84 1.7 49.4 1.9 10.sup.3 This work UV- Batch photo-reactor (5 8 W 5.1 BPA 39.6 72.5 360 0.08 951 .sup.73 PMS mercury UV-C light; = 254 nm) UV- Batch photo-reactor (5 4 W 7 Sodium 0.66 100 180 0.0037 300 .sup.74 PMS mercury UV-C light; alginate = 254 nm) UV- Co.sup.2+ Batch photo-reactor (300 W NA Acid 26.9 73 300 0.0655 5276 .sup.75 PMS mercury UV light; orange 7 365 nm) UV- T@MPAC Batch photo-reactor (6 W 7 Benzo- 36.3 58.5 120 0.177 157 .sup.76 PMS UV-C light) triazole UV- -Fe.sub.2O.sub.3@AC Batch photo-reactor (6 W 4 Cyfluthrin 36.5 52.4 80 0.239 49.6 .sup.77 PMS UV-C light; = 254 nm) VUV- Fe.sup.2+ Batch photo-reactor (8 W 7 Norflox- 8.64 88.85 24 0.32 13.4 .sup.78 PMS vacuum UV light; acin .sub.1 = 185 nm; .sub.2 = 254 nm) UV- MNPs@C Batch photo-reactor (6 W 6.5 Acetamin- 12.7 63.5 40 0.202 18.3 .sup.79 PMS UV-C light; = 254 nm) ophen UV- ZnO@SiO.sub.2@Fe.sub.3O.sub.4 Batch photo-reactor (8 W 9 Diazinon 9.5 56 60 0.0887 74.8 .sup.80 PMS UV-C light; = 254 nm) UV/PMS CoFe.sub.2O.sub.4@CNT Batch photo-reactor (8 W 5.5- BPA 31.5 72.6 60 0.381 47.4 .sup.81 UV-C light; = 254 nm) 6 UV- ZnO-GAC Batch photo-reactor (6 W 6.2 Reactive 31.46 43.6 60 0.229 104.9 .sup.82 PMS UV-C light; = 256 nm) Black 5 UV- AuTiO.sub.2 Batch photo-reactor (3 250 5.8 Ceftiofur 11.4 96 600 0.0182 53650 .sup.83 Vis- W lamp; = 360-2000 nm) sodium PMS UV/US/ MNPs@C Batch photo-reactor (UV 6 BPA 23.65 56.4 60 0.222 2857 .sup.84 PMS lamp 6 W; ultrasonic power 200 W) UV/US/ Fe/CMK-3 Batch photo-reactor (UV 7.8 BPA 31 80.6 78.5 0.318 99 .sup.85 PMS lamp 125 W; ultrasonic power 80 W) UV/EC/ Fe.sub.3O.sub.4 Photoelectro-Fenton reactor 5 Washing 202 97.1 180 1.09 624 .sup.86 PMS (4 W UV-C light; machine = 254 nm; effluent DC power: 2000 mA, 30 V) UV/US/ Batch photo-reactor (UV 10.2 WW-IS 340 80 60 4.53 6073 .sup.87 PMS/PDS intensity 4.1 W cm.sup.2; ultrasonic power 1280 W) UV- Batch photo-reactor (6 W 7 Sucralose 18 93 60 0.279 20.8 .sup.88 PDS UV-C light; = 254 nm) UV- Fe(OH).sup.2+ Batch photo-reactor (5 W 3 Sul- 4.8 91 120 0.0364 191 .sup.89 PDS LED lamp; = 365 nm) fameth- oxazole UV/H.sub.2O.sub.2 Batch photo-reactor (10 W 7 Roxarsone 3.7 43.2 60 0.0266 203.5 .sup.90 UV-C light; = 254 nm) UV/H.sub.2O.sub.2 Batch photo-reactor (40 W 3 Phenol 37 87 120 0.268 47.5 .sup.91 UV-C light; = 253.7 nm) UV/H.sub.2O.sub.2 Batch photo-reactor (8 W 3 Orange II 38.4 60 120 0.192 80.4 .sup.92 UV light) UV/H.sub.2O.sub.2 Fe.sup.2+ Batch photo-reactor (12 1.4 3 Elderberry 459 99 90 5.049 25.2 .sup.93 W UV-A LED lamp) waste- water UV/H.sub.2O.sub.2 Fe.sup.3+ Batch photo-reactor (250 W 2 Sulfonated 3250 99 250 12.87 20833 .sup.94 Hg(Xe) light source) cross- linked poly- styrene UV/H.sub.2O.sub.2 Fe.sup.0 Batch photo-reactor (6 W 7.3 Secondary 8.3 92.1 360 0.0212 65.3 .sup.95 UV-C light; = 254 nm) waste- water effluent UV/H.sub.2O.sub.2 Amorphous iron Batch photo-reactor (4 13 4 Phenol 76.5 96 180 0.408 744 .sup.96 oxide W fluorescent lamp; = 350-400 nm) UV/H.sub.2O.sub.2 Fe-clay Batch photo-reactor (8 W 3 Orange II 38.4 100 120 0.32 16 .sup.97 UV-C light; = 254 nm) UV/H.sub.2O.sub.2 Fe-Lap-RD Batch photo-reactor (8 W 3 Reactive 39.46 76 120 0.25 14.3 .sup.98 UV-C light; = 254 nm) Red HE-3B UV/H.sub.2O.sub.2 Fe-pillared clay Batch photo-reactor (15 W 5.2 P- 21.6 52.3 180 0.0628 1400 .sup.99 UV-C light; = 254 nm) amino- benzene- sulfa- nilnamide UV/H.sub.2O.sub.2 CeFe/Al.sub.2O.sub.3 Batch photo-reactor (72 W 6 Yeast 347.6 96.9 120 2.81 47.7 .sup.100 UV-C light; 36 W UV-A plant light) waste- water UV/H.sub.2O.sub.2/ Waterfall photocatalysis 4 Aniline 33 49 90 0.18 164.1 .sup.101 PDS (2 8 W UV-C light; = 254 nm) EC/PMS Ti/SnO.sub.2Sb Batch two-chamber reaction NA PFNA 11.64 85.2 90 0.11 51.4 .sup.102 cells (voltage 8.3 V; current 0.25 A) EC/PDS SnO.sub.2Al.sub.2O.sub.3/CNT Batch two-chamber reaction 3 Ceftaz- 20 45 150 0.06 11.6 .sup.103 cells (voltage 1.5 V vs. idime SCE; current 0.06 A) EC/H.sub.2O.sub.2 Fe.sup.2+/Fe.sup.3+ Batch one-chamber reaction 6.8 Landfill 649 73 80 5.92 9.4 .sup.104 cell (voltage 12 V; current leachate 0.2 A) EC/H.sub.2O.sub.2 Pyrite Batch one-chamber reaction 3 Tyrosol 28.8 89 360 0.0712 136.7 .sup.105 cell (voltage 18.2 V; current 0.3 A) EC/H.sub.2O.sub.2 FeOx/NHPC Batch one-chamber reaction 6 Phenol 38.3 83 420 0.0757 11.6 .sup.106 cell (voltage 0.6 V; current 0.064 A) Direct Ti/IrO.sub.2 anode Batch one-chamber reaction 5.6 Crystal 147 31 80 0.57 5.79 .sup.107 EC (Cl.sup./ cell (voltage 3.5 V; current violet H.sub.2O) 0.03 A) Direct Boron-doped Batch one-chamber reaction 7.57 Effluent 9.6 79.03 210 0.036 184 .sup.108 EC diamond anode cell (voltage 8 V; current from (H.sub.2O) 1.56 A) Badajoz WWTP Direct Boron-doped Rotating disk electrode 4 PFOS 38.4 95 25 1.46 0.512 .sup.109 EC diamond film reactor (voltage 3.2 V vs. (H.sub.2O) SHE; current 0.5 A) Direct Boron-doped Batch undivided 7.6- Poly- and 99 91.1 600 0.15 254.85 .sup.110 EC diamond anode flow-by cell (voltage 15.3 8.4 perfluoro- (H.sub.2O) V; current 3.5 A) alkyl substances (PFASs) Direct Ti/SnO.sub.2Sb Batch one-chamber reaction 7.1 Coking 35 74.56 120 0.217 25.95 .sup.111 EC anode cell (voltage 1.62 V; current waste- (H.sub.2O) 0.625 A) water Direct Porous Ti.sub.4O.sub.7 Batch one-chamber reaction N.A. PFOA 48 95 120 0.38 10.38 .sup.112 EC Ceramic cell (voltage 2.7 V vs. SHE; (H.sub.2O) current 0.25 A) Direct Ti/ Batch one-chamber reaction 3 M-cresol 155.4 61 480 0.197 7.33 .sup.113 EC (anode) + SnO.sub.2Sb.sub.2O.sub.5IrO.sub.2 cell (voltage 1.0 V of EC/H.sub.2O.sub.2 anode; cathode potential; current (cathode) carbon-nanotube 0.09 A) cathode EC- Carbon-PTFE Batch one-chamber column 3 Oxalic 48 95.3 60 0.76 5.87 .sup.114 peroxone cathode reactor (voltage 7.8 V; acid current 0.4 A) .sup.73 Sharma, J., et al., Chem. Eng. J. 276, 193-204 (2015) .sup.74 Alayande, A. B., et al., Desalination 522: 115437 (2022) .sup.75 Chen, X. Y., et al., Chemosphere 67, 802-808 (2007) .sup.76 Jorfi, S., et al., Appl. Catal. B-Environ. 219, 216-230 (2017) .sup.77 Khaghani, R., et al., Micropor. Mesopor. Mat. 284, 111-121 (2019) .sup.78 Wang, C., et al., J. Hazard. Mater. 422: 126884 (2022) .sup.79 Noorisepehr, M., et al., Chemosphere 232, 140-151 (2019) .sup.80 Rezaei, S. S., et al., J. Environ. Manage. 250: 109472 (2019) .sup.81 Kakavandi, B., et al., Chemosphere 287: 132024 (2022) .sup.82 Liu, F. Z., et al., Sep. Purif. Technol. 279: 119754 (2021) .sup.83 Pugazhenthiran, N., et al., Chem. Eng. J. 241, 401-409 (2014) .sup.84 Takdastan, A., et al., Chem. Eng. J. 331, 729-743 (2018) .sup.85 Rahimzadeh, H., et al., Water Environ. Res. 92, 189-201 (2020) .sup.86 Ghanbari, F. & Martinez-Huitle, C. A. J. Electroanal. Chem. 847: 113182 (2019) .sup.87 Grcic, I., et al., Water Res. 46, 5683-5695 (2012) .sup.88 Xu, Y., et al., Chem. Eng. J. 285, 392-401 (2016) .sup.89 Yan, S., et al., Sep. Purif. Technol. 274: 118991 (2021) .sup.90 Chen, L., et al., J. Hazard. Mater. 410: 124558 (2021) .sup.91 Olmez-Hanci, T. & Arslan-Alaton, I. Chem. Eng. J. 224, 10-16 (2013) .sup.92 Feng, J. Y., et al., Water Res. 39, 89-96 (2005) .sup.93 Amor, C., et al., Environ. Technol. Inno. 21: 101183 (2021) .sup.94 Feng, H. M., et al., Environ. Sci. Technol. 45, 744-750 (2011) .sup.95 Pan, Y. W., et al., Water Res. 153, 144-159 (2019) .sup.96 Huang, C. P. & Huang, Y. H. Appl. Catal. A-Gen. 357, 135-141 (2009) .sup.97 Feng, J. Y., et al., Water Res. 40, 641-646 (2006) .sup.98 Feng, J. Y., et al., Water Res. 37, 3776-3784 (2003) .sup.99 Khankhasaeva, S. T. & Badmaeva, S. V. Water Res. 185: 116212 (2020) .sup.100 Wei, C. H., et al., J. Cent. South Univ. 13, 481-485 (2006) .sup.101 Duran, A., et al., Chemosphere 186, 177-184 (2017) .sup.102 Wang, K. X., et al., Sci. Total Environ. 758: 143666 (2021) .sup.103 Duan, P. Z., et al., J. Environ. Chem. Eng. 8: 103812 (2020) .sup.104 Ghanbari, F., et al., Chemosphere 279: 130610 (2021) .sup.105 Ammar, S., et al., Water Res. 74, 77-87 (2015) .sup.106 Cao, P. K., et al., J. Hazard. Mater. 382: 121102 (2020) .sup.107 Copete-Pertuz, et al., Sci. Total Environ. 772: 145449 (2021) .sup.108 Dominguez, J. R., et al., J. Environ. Manage. 298: 113538 (2021) .sup.109 Carter, K. E. & Farrell, J. Environ. Sci. Technol. 42, 6111-6115 (2008) .sup.110 Ruiz, B. G., et al., Chem. Eng. J. 322, 196-204 (2017) .sup.111 He, L., et al., Chemosphere 288: 132362 (2022) .sup.112 Lin, H., et al., Chem. Eng. J. 354, 1058-1067 (2018) .sup.113 Chu, Y. Y., et al., J. Hazard. Mater. 252, 306-312 (2013) .sup.114 Wang, H. J., et al., Water Res. 80, 20-29 (2015)
DISCUSSION
[0128] The unprecedently high mineralization performance of the CoHCC membrane can be attributed to its unique catalyst structure that efficiently produces both SO.sub.4.sup. and OH via PMS activation (
[0129] Another critical reason for the high mineralization performance of the CoHCC membrane is the spatial confinement of surface-catalyzed reactions. All the radical-mediated reactions leading to organic oxidation and mineralization occur inside membrane nanochannels (pore diameter <20 nm) during the flow-through treatment. This nanoscale spatial confinement allows for maximized contact between short-lived radicals (SO.sub.4.sup. lifetime=30-40 s and OH<10 s).sup.17,70 and the target organic pollutant molecules that pass through the pores. In addition, catalysts immobilized inside the pores provide more accessible surface area compared to catalysts suspended in water. Suspended catalysts undergo severe agglomeration at a concentration higher than 5 g L.sup.1 (
Methods
[0130] Catalyst synthesis. The CoHCC catalyst was synthesized using a newly established hydrothermal method. First, 0.55 M glucose and 0.25 M cobalt nitrate hexahydrate were dissolved in deionized water. A ceramic membrane was immersed in this mixture solution, which was then sonicated for 1 hour before being placed on a shaker plate for 24 hours to ensure the penetration of the precursor solution into the pores. The membrane and solution were heated to 260 C. in an autoclave with a temperature ramp rate of 5 C. min.sup.1, kept for 15 h, and naturally cooled to room temperature. The as-synthesized membrane was washed by ethanol and deionized water several times and dried in a vacuum oven before use. The catalyst particles were synthesized following the same procedure but without addition of ceramic membrane.
[0131] Synthesis of CoHCC.sub.pre, CoFe.sub.2O.sub.4, and CO.sub.3O.sub.4. Cobalt hexacyanocobaltate with typical (200) facet (i.e., CoHCC.sub.pre) was synthesized using a standard precipitation method with K.sub.3Co(CN).sub.6precursor and cobalt salt (Deng, L. Q., et al., Adv. Mater. 30: 1802510 (2018); Kaye, S. S. & Long, J. R. J. Am. Chem. Soc. 127, 6506-6507 (2005)). Specifically, K.sub.3Co(CN).sub.6 (40 mM) was added dropwise into CoCl.sub.2 solution (60 mM) under mixing, with dosing rate of 0.5 mL min.sup.1. The resulting precipitate was centrifuged and washed at least three times with deionized water, and then dried overnight in a vacuum oven. For the synthesis of CoFe.sub.2O.sub.4, a 50 mL solution containing FeCl.sub.3 (0.2 M) and CoCl.sub.2 (0.1 M) was prepared and then dropwise added to 500 mL NaOH solution to form precipitates. The dark brown precipitates were washed by deionized water several times, dried in air at 80 C. for 6 h, annealed under Ar gas at 500 C. for 4 h. For the synthesis of CO.sub.3O.sub.4, 0.17 M cobalt nitrate hexahydrate was dissolved in 10 mL of ethanol solution and heated at 180 C. (temperature ramp rate of 5 C. min.sup.1) for 4 h 180 C. The precipitates were washed with ethanol and deionized water three times, and then dried in air at 80 C. for 6 h.
[0132] Catalyst characterization. The morphology of catalyst was examined by SEM (Hitachi SU-70) and TEM (JEM-2000EX, Japan). XRD patterns were acquired using a Rigaku SmartLab X-ray diffractometer with Cu K monochromatic radiation operated at 40 kV and 44 mA. Elemental spectra and mapping were captured by EDS coupled with a cold field emission scanning electron microscope (Hitachi SU8230). XPS was conducted on a PHI VersaProbe II Scanning XPS Microprobe with monochromatic Al K radiation (1486.6 eV). X-ray absorption spectroscopy (XAS) spectra were collected using a Beamline 8-ID (ISS) of the National Synchrotron Light Source II (Brookhaven National Laboratory, USA), using a Si (111) double crystal monochromator and a passivated implanted planar silicon detector. XAS data were collected at room temperature, energy calibrated with Co foil, and were processed using Demeter XAS analysis software.
[0133] Batch and membrane reaction tests. Stock solution for batch reaction (50 mL) contained PMS and model organic compound at pH 7.0. The catalyst powders were first dispersed under sonication and then transferred to the stock solution to initiate the reaction. Samples periodically taken from the reactor were immediately mixed with abundant methanol to quench radicals, centrifuged to remove the solid phase, and analyzed using HPLC. The membrane reactivity was tested using a dead-end filtration setup. In a typical experiment, the catalytic membrane was first fixed inside the reaction module and sealed tightly by O-ring rubber bands to avoid water leakage. The stock solution containing PMS and organic pollutants was fed into the membrane module at prescribed flow rates. For the long-term performance test, the stock solution was replenished every 24 h. The permeate sample was collected and immediately analyzed using HPLC and TOC.
[0134] Radical and organic detection. EPR was performed with a Bruker A200 spectrometer (Germany) using 5,5-dimethylpyrroline-oxide (DMPO, 98%) as a spin-trapping agent. The concentration of BPA was detected at 230 nm by HPLC (Agilent Technologies 1260 Infinity), using a 5 m Eclipse XDB-C18 column (4.6 mm150 mm) as the stationary phase. The mobile phase was acetonitrile (50%) and 0.1% phosphoric acid solution (50%) with a flowrate of 1 mL min.sup.1. The TOC concentrations were determined using a Shimadzu TOCVCSH analyzer.
[0135] Computational methodology. All the DFT calculations were performed using the Vienna Ab initio Simulation Package (VASP) with the projector augmented wave (PAW) method. The exchange-functional was treated using the generalized gradient approximation (GGA) with Perdew-Burke-Emzerhof (PBE) functional. The energy cutoff for the plane wave basis expansion was set to 400 eV. Partial occupancies of the Kohn-Sham orbitals were allowed using the Gaussian smearing method and a width of 0.2 eV. The bulk structure of CoHCC (10 Co atoms, 12 C atoms, and 12 N atoms), CO.sub.3O.sub.4 (24 Co atoms, and 32 0 atoms), and CoFe.sub.2O.sub.4 (8 Co atoms, 12 Fe atoms, and 32 0 atoms) were optimized with the Monkhorst-Pack k-point of 333. The Monkhorst-Pack k-point of 22 1 was applied for the optimizations on CoHCC (100), CoHCC (110) and CoN.sub.4 surfaces, and 22 1 for CO.sub.3O.sub.4 (311) and CoFe.sub.2O.sub.4 (311) surfaces. The self-consistent calculations apply a convergence energy threshold of 10.sup.5 eV, and the force convergency was set to 0.05 eV/A. The Gibbs free energy (G, eV) corrections were considered at the temperature of 298 K, following G=E+GZPE+GuTS, where E, GZPE, Gu, and S refer to the DFT calculated energy change, the correction from zero-point energy, the correction from inner energy and the correction from entropy, respectively.
[0136] Determination of the turnover frequency (TOF). The TOF (mole g.sup.1 min.sup.1) can be calculated by dividing the reaction rate of pollutants with radicals by the catalyst concentration,
where C.sub.org. is the molar concentration of organic pollutants, M; .sub.99% is time spent for a 99% conversion of organic pollutants by radicals, min (this can be determined by ln(0.01)/k.sub.obs,catal, where k.sub.obs,catal. is the apparent pseudo-first order rate constant); and C.sub.catal. is the concentration of catalyst used for reaction, g L.sup.1.
[0137] Note that SO.sub.4.Math..sup. is the direct product of PMS activation and is highly reactive with all the model organics tested (second-order rate constant, k.sub.SO.sub.
where k.sub.BPA,SO.sub.
[0138] Estimation of radical productivity in membrane and radical consumptionThe theoretical production rate of radicals (R.sub.tp, M s.sup.1) can be estimated based on the catalyst's TOF and concentration within the membrane, as expressed in equation 3,
where C.sub.m,catal is the concentration of catalyst within the membrane, g L.sup.1.
[0139] The total consumption rate of radicals can be expressed as the sum of the SO.sub.4.sup. consumption rate (R.sub.c,SO4M s.sup.1) and the OH consumption rate (R.sub.c,OH, M s.sup.1), as can be expressed in equations 4 and 5
where C.sub.SO.sub.
[0140] Noting that the product of OH and Cl.sup. interactions, i.e., ClHO, would quickly decompose back to OH and Cl.sup. again (k.sub.ClHO.sup.=6.110.sup.9 M.sup.1 s.sup.1).sub.3, the first term in equation 5 can be eliminated and then the total consumption rate of radicals (R.sub.c,total) can be expressed in equation 6,
[0141] Determination of EEO. EEO refers to the number of kilowatt-hours (kWh) of electrical energy required to reduce the TOC by one order of magnitude (90%) in 1 m.sup.3 of contaminated water (unit: kWh/m.sup.3/order). Its value can be calculated by
where E.sub.op is the output power, kW; .sub.0.1 is the time required for 90% reduction of TOC, h; and V.sub.ris the liquid volume for reaction, m.sup.3.
[0142] The EEO for the membrane was determined by equation 8,
where P is the transmembrane pressure, about 6.89 kPa for 20 LMH; and V is a unit water volume, 1 m.sup.3.
[0143] Cost analysis. The cost for TOC removal (C.sub.TOC, $ per mg-C) was calculated through dividing the cost for the treatment of each cubic meter wastewater (C.sub.V, $ m.sup.3) by the removed TOC (mg-C L.sup.1), expressed as
[0144] The parameter C.sub.V can be calculated as a sum of the cost of chemical reagents (C.sub.C, $ m.sup.3) and the cost of photoand/or electrical energies (C.sub.E, $ m.sup.3). The Cc can be obtained by multiplying the concentration of chemical precursors used for the generation of radicals (Cp, kg m.sup.3) with their market price (P.sub.M, $ kg.sup.1), and the C.sub.E can be obtained by multiplying the EEO (kWh/m.sup.3/order) with the price of energy (P.sub.E, $ per kWh; this was assessed with 0.116 $ per kWh according to the USA generation services charge).
[0145] Then, the C.sub.y can be calculated based on equation 10,
[0146] Determination of SO.sub.4.sup. and OH concentrations. The steady-state concentration of SO.sub.4.Math..sup. can be calculated by equation 11, with the assumption that TBA has completely quenched OH and methanol has completely quenched SO.sub.4.sup..
where k.sub.obs,TBA is the rate constant of BPA degradation in the presence of TBA, s.sup.1; k.sub.obs,methanol is the rate constant of BPA degradation in the presence of methanol, s.sup.1; and k.sub.BPA/SO.sub.4 is the second-order rate constant for BPA in reaction with SO.sub.4, 4.4910.sup.9 M.sup.1 s.sup.1
[0147] The steady-state concentration of OH can be calculated by equation 12:
where k.sub.obs,catal. is the rate constant of BPA degradation with catalyst, s.sup.1; and k.sub.BPA/OH is the second-order rate constant for BPA in reaction with OH, 6.910.sup.9 M.sup.1 s.sup.1.6.
[0148] Hydrothermal Treatment. Hydrothermal treatment (180-240 C.) of glucose as a typical saccharide produces carbonaceous microspheres (Romero-Anaya, A. J., et al., Carbon 68, 296-307 (2014)), along with abundant oxygen groups in the shells of the particles (Sevilla, M. & Fuertes, A. B., et al., Carbon 47, 2281-2289 (2009). This is quite similar to the spherical carbon particles that we collected after hydrothermal treatment at 240 C. (
[0149] Structure Analyses. EXAFS is a powerful tool that can allow the determination of CN and coordinating atom identity. CoHCC to appears to have a repeating Co.sup.IINCCo.sup.III structure, which introduces complications to conducting a fit to find CN. Mainly, this proposed structure contains multiple Co atoms linearly in a path (
[0150] BPA Removal Rate. The removal rate of BPA continuously decreased with reduced retention time caused by the increased water flux. According to the BPA concentration in the permeate relative to that in the inlet solution (C.sub.out, BPA/C.sub.in, BPA) versus the retention time (inset figure), one can see that the relevant data exhibited good linear correlation (R.sup.2>0.98), and thus one can obtain the apparent reaction constant by this membrane reactor (k.sub.obs,membrane, s.sup.1) Then the steady-state concentrations of SO.sub.4.sup. (C.sub.SO.sub.
[0151] Considering that the second-order rate constants for BPA in reaction with SO.sub.4.sup. (4.4910.sup.9 M.sup.1 s.sup.15) and OH (6.910.sup.9 M.sup.1 s.sup.16) are quite close to each other, the terms for second-order constants can be approximated with a value of 5.710.sup.9 M.sup.1 s.sup.1. Note that the relative abundance of SO.sub.4.Math..sup. and OH was about 0.83/0.62, and so one can respectively get C.sub.SO.sub.
[0152] Selection of organic pollutants for TOC analysis. Given the complexity of organic constituents in real wastewater, model compounds were selected based on their prevalence in literature and existing databases. Aniline and Rhodamine B (RhB) were chosen as representative chemicals in the paper and chemical industries, respectively, as documented by the U.S. EPA Toxics Release Inventory (TRI) Pollution Prevention Industry Profile database. Terephthalic acid (TPA) is a major pollutant reported in the food industry. For hospital wastewater, acetaminophen (APAP) was selected as a pharmaceutical present in these effluents that poses major public health risks. For municipal wastewater, natural organic matter (NOM) and 4-chlorophenol (4-CP) were chosen for their widespread abundance. Organic matter in particular can become highly concentrated in RO-based processes, in which oxalic and other carboxylic acids have been noted to be relatively more stable and difficult to mineralize in the post-treatment steps. Hence, oxalic acid (OA) was chosen as a model organic pollutant in the scope of ROC solutions.
[0153] The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. While this invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention. The appended claims are intended to be construed to include all such embodiments and equivalent variations.