Photocatalytic composite material and method for repairing water and / or sediments by using photocatalytic composite material

Abstract

The present teachings describe photocatalytic composites useful in the remediation of bodies of water, such as lakes, ponds, wetlands and paddy fields, as well as in the remediation of underwater deposits.

Description

[0001] Related Applications This application claims the benefit of and priority to U.S. Patent Application No. 63 / 490,596, filed March 16, 2023, and U.S. Patent Application No. 63 / 607,212, filed December 7, 2023, the entire contents of each of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present teachings relate to water and / or sediment remediation using a photocatalytic composite material that floats or suspends in a water body in need of remediation. BACKGROUND

[0003] As industrial production and recreational facilities expand globally, the scope of water quality issues continues to expand. Sewage, agricultural and industrial wastewater, and recreational activities, aquaculture and human waste disposal, all contribute to globally pandemic damaging water bodies (eutrophication), large and small, cost-ineffective, low-carbon profile strategies for their remediation to natural sustainable states.

[0004] Many new and recycled technologies have been deployed globally to prevent and offset symptoms of positive nutrition (algae blooms, most urgently, blue-green algae (“BGA”) and red algae), predictably with little success. While attempts to reduce pollutants can have an impact, broader environmental trends and history suggest that abstinence is not the answer. Water is 80% of our planet and has played a central role in human endeavor and ingenuity. Developing strategies for reducing pollutants by absorbing or breaking down harmful materials and heavy metals in water bodies, including the use of mechanical and biological catalysts, precipitating suspended solids by adding a polyelectrolyte coagulant or proliferating foreign microorganisms with enzyme additives, only addresses half the problem—water clarification and temporary algal retardation, while actually contributing to a death spiral on the wrong side of the zero-sum water versus sedimentation equation.

[0005] The widespread industrial use of water resources combined with predictably expanding agricultural runoff from deployed chemical fertilizers to offset declining soil productivity, overwhelms the planet’s natural carbon cycle, which relies on healthy lakes to break down carbon waste and present it to the sun for photosynthesis. This breakdown means that solutions are needed to clarify water and remove accumulated sediment. Stated directly, small waterways with high turbidity cannot self-remediate—simply moving the constant delivery of suspended solids to the bottom, reducing water capacity, leads to reduced water capacity to be overcome more quickly by increasing levels of environmental deprivation.

[0006] At that time, nature dispatched its top predator, BGA, to attack and feast on the suspended nutrients of the Lake of the Sustained Feast - soon, only BGA could process the available nutrients that had shifted from widely consumable carbon to nitrogen and phosphorus locked in sediment. Alternative methods, like filters and air injection used in aquaculture, provided some limited ability to counteract eutrophication in the context of small profit operations, but extrapolating the use of electricity and mechanical force to repair water bodies, beyond a few feet deep, or a few acres in area, is economically or logistically infeasible.

[0007] The industry desires a system to repair water back to its natural state and dissolve and transform sediment without mechanical or powered electrical stimulation. SUMMARY

[0008] The present teachings provide revolutionary technology for a product (i.e., a photocatalytic composite) that accelerates algal mediation and can augment the natural ability of water bodies to reduce chemical oxygen demand, total organic content, and / or excess nutrients (e.g., phosphorus and nitrogen). The present teachings can provide photocatalytic algal mediation that provides a new paradigm to significantly reduce and control marine sediment without the use of non-natural microbial additives or continuous mechanical (e.g., dredging) or electrical manipulation. The product of the present teachings can provide fast, scalable solutions that can be optimized for use in lakes, rivers, estuaries, wetlands, rice paddies, aquaculture farms, and open seawater.

[0009] The present teachings can improve water quality in these waters through targeted delivery and activation of photocatalyst nanocomposites in conjunction with biopolymer polyelectrolytes. This underlying technology is effective for different environmental challenges and can also be used in combination with other methods for large-scale water remediation and enhanced yield and quality in aquaculture.

[0010] In one aspect, the present teachings generally provide a photocatalytic composite that includes titanium dioxide and silver nanoparticles and a polyelectrolyte that is typically not as dense as water so that it can float and remain suspended in water. The photocatalytic composite can also include another polymer, such as polyvinylpyrrolidone. The photocatalytic composite can include selenium and / or copper. The photocatalytic composite also includes a solvent so that the photocatalytic material is coated or encapsulated with, for example, the polyelectrolyte and other polymers as a dispersion or colloidal mixture. Due to the high molecular electrolyte, the photocatalytic composite is less dense than water so that it floats on and / or remains suspended at or near the water surface to maintain maximum visible light and sunlight exposure.

[0011] More specifically, the photocatalytic composites of the present teachings generally include TiO2-coated Ag ("(TiO2) n / Ag") nanoparticles in a polyelectrolyte (e.g., chitosan or a chitosan substrate (CS)), wherein the (TiO2) n / Ag particles are associated with the polyelectrolyte (e.g., chitosan or CS), all in a solvent. (Here, while only for notational purposes, n can be an integer greater than zero, e.g., from about 10 to about 250.)(TiO2) n / Ag particles can further be associated with another polymer. The solvent typically includes an acid.

[0012] In some embodiments, the photocatalytic composites of the present teachings generally include TiO2-coated Ag ("(TiO2) n / Ag") nanoparticles and selenium (Se), wherein the (TiO2) n / Ag particles and Se are associated with a polyelectrolyte (e.g., chitosan), all in a solvent. The (TiO2) n / Ag particles and Se can further be associated with another polymer. The solvent typically includes an acid.

[0013] In some embodiments, the photocatalytic composites of the present teachings generally include TiO2-coated Ag ("(TiO2) n / Ag") nanoparticles and copper (Cu), wherein the (TiO2) n / Ag particles and Cu are associated with a polyelectrolyte (e.g., chitosan), all in a solvent. The (TiO2) n / Ag particles and Cu can further be associated with another polymer. The solvent typically includes an acid.

[0014] In some embodiments, the photocatalytic composites of the present teachings generally include TiO2-coated Ag ("(TiO2) n / Ag") nanoparticles, Se and Cu, wherein the (TiO2) n / Ag particles, Se and Cu are associated with a polyelectrolyte (e.g., chitosan), all in a solvent. The (TiO2) n / Ag particles, Se and Cu can further be associated with another polymer. The solvent typically includes an acid.

[0015] In various embodiments, the photocatalytic composites can include TiO2-coated AgCl ("(TiO2) n / AgCl") particles as the (TiO2) ncounter electrodes for Ag particles that enhance the photocatalytic and electron transfer activity of the material. For example, the photocatalytic composite can comprise (Ti02) n / Ag particles and (Ti02) n / AgCl particles and a polyelectrolyte, and optionally, another polymer in a solvent. These embodiments can also include Se and an acid.

[0016] In some embodiments, the photocatalytic composite can comprise Ti02and Se-coated Ag ("Ti02 / Ag / Se") particles, Ti02and / or Se-coated AgCl ("Ti02 / AgCl / Se") particles. In various embodiments, Cu can be substituted for or in addition to Se in these particles.

[0017] In another aspect, the present teachings provide a method of making a photocatalytic composite, wherein the method generally comprises mixing Ti02, Ag, and another polymer in a first solvent to form a first mixture; and exposing the first mixture to a reducing agent until less than about 20% of the Ag is Ag+to form a reduced mixture; mixing a cationic polyelectrolyte (optionally an acid) and other polymer in a second solvent to form a second mixture; and adding the second mixture to the reduced mixture, thereby forming the photocatalytic composite.

[0018] In some embodiments, the mixing further comprises mixing Se and / or Cu in the first solvent. In various embodiments, the reducing agent comprises ultraviolet radiation, microwaves, or a combination thereof.

[0019] In another aspect, the present teachings provide a method of water and / or sediment remediation, comprising contacting a photocatalytic composite as described herein with a body of water in need of remediation, and exposing the photocatalytic composite to visible light and / or sunlight for a suitable time and under conditions suitable for the photocatalytic composite to convert a contaminant compound in the body of water into one or more different compounds. In certain embodiments, the one or more different compounds is an oxidized contaminant compound. In various embodiments, the body of water is an open body of water. In some embodiments, the body of water is a wetland or a rice field.

[0020] In certain embodiments, particularly in wetlands and rice fields, the present teachings provide a method of reducing methane emissions during water remediation, comprising contacting a body of water with a photocatalytic composite as described herein; and exposing the photocatalytic composite to visible light and / or sunlight for a suitable time and under conditions suitable for the photocatalytic composite to convert methane in the body of water into one or more different compounds. BRIEF DESCRIPTION OF DRAWINGS

[0021] It should be understood that the drawings described below are for illustration purposes only. Like reference numbers in different drawings generally refer to the same or similar elements. The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the present teachings. The drawings are not intended to limit the scope of the present teachings in any way.

[0022] Figure 1A and Figure 1B are schematic illustrations of photocatalytic composites, wherein Figure 1A comprise (Ti02) n / Ag nanocomposites and (Ti02) n / AgCl nanocomposites; and Figure 1B comprise (Ti02) n / Ag composites and (Ti02) n / AgCl composites, wherein Se is present. DETAILED DESCRIPTION

[0023] The present teachings describe photocatalytic composites that can repair water through the action of its various components. The photocatalytic composites are formulated to disperse on and in water, which photocatalytic composites can effectively and efficiently activate the production of ionized species and free radicals under natural light (e.g., visible light and / or sunlight) that break down harmful materials and polluting compounds in water, which can reduce chemical oxygen demand ("COD") and allow access to additional available oxygen for aerobic bacteria.

[0024] Using more available oxygen, aerobic bacteria can compete more effectively with BGA to consume available phosphorus, naturally repairing BGA blooming and diversifying the algae, enhancing oxygen availability and further diversifying the food chain away from the primary consumer (i.e., BGA). Reduced BGA naturally reduces nitrogen oxides (NOx) into the water body, thereby not only repairing phosphorus but also nitrogen.

[0025] The photocatalytic components of the materials of the present teachings include Ti02associated with silver (Ag) nanoparticles, such that many Ti02particles are themselves associated with Ag particles ((Ti02) n / Ag). The photocatalytic components can also comprise silver chloride particles ((Ti02) n / AgCl), which act as a counter electrode to the (Ti02) n / Ag particles.

[0026] In certain embodiments, the photocatalytic components also include Se, which can help the electron transfer process as an electron acceptor for the electron donor, which is Ag. In some embodiments, the photocatalytic composites also include Cu.

[0027] The photocatalytic composites of the present teachings can also include a polymer of natural origin that is engineered to have positively charged moieties (i.e., polycations) to bind to and aggregate algal blooms and organic molecules to the clear water column for enhanced penetration of light deeper into the water. That is, the cationically charged polyelectrolyte interacts with the negatively charged algae and associated organic matter causing agglomeration and compaction of this structure, clearing a larger light penetration path and reaching the photocatalytic components in the photocatalytic composites into the water. Over time, such agglomeration and compaction can settle completely out of the water, to places at the bottom of the water, where further remediation activity can occur using the materials of the present teachings.

[0028] Further, the density of the polyelectrolyte (e.g., chitosan) can be less than water, such that it will float and keep the photocatalytic composites suspended in the water near its surface and dispersed therein for long periods of time, e.g., up to three days, a week, or more. This feature of the polyelectrolyte allows the photocatalytic components of the photocatalytic composites to be exposed to visible light and, in particular, sunlight, to generate the ionic species and free radicals necessary to break down undesirable substances and pollutant compounds in the water and to create an oxygen-rich, pH neutral environment. That is, the polyelectrolyte can allow the photocatalytic composites to float on or near the surface of the water to maximize exposure to visible light and / or sunlight, thereby initiating the remediation photocatalytic activity.

[0029] Definitions To facilitate the understanding of this application, a number of terms and phrases are defined below.

[0030] Unless defined otherwise, all technical and scientific terms and phrases used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Abbreviations used herein have their conventional meaning within the chemical and biological arts. Chemical structures and formulas set forth herein are constructed according to standard rules of chemical valency known in the chemical arts.

[0031] The terms "a" and "an," as used herein, mean "one or more" and include the plural unless the context is inappropriate.

[0032] In this application, words to the effect that one "element" or "component" are encompassed by the phrase "comprising," or variants such as "comprise," "include," "including," and the like, are intended to mean one or more element or component, unless the context is inappropriate.

[0033] Further, it should be understood that elements and / or features of a composition or method described herein can be combined in a variety of ways without departing from the spirit and scope of the present teachings, whether explicit or implicit herein. For example, where a particular compound is mentioned, that compound can be used in different embodiments of a composition of the present teachings and / or in methods of the present teachings, unless otherwise understood from the context. In other words, in this application, the use of "embodiment" or "exemplary embodiment" or other similar expressions, means an embodiment or an exemplary embodiment, for the purpose of enabling a clear and concise application. But, the application is not intended to be limited to that embodiment or exemplary embodiment. Therefore, the scope of the present teachings are to be understood as including any variation from these embodiments or exemplary embodiments that come within the scope of the present teachings and that obvious variants to a person skilled in the art and as covering any and all equivalents. Furthermore, to the extent that there are "consisting" embodiments of the present teachings, they do not exclude additional material or moieties. To the extent that there is talk of "consisting of" or "consisting only of" in this document, this should be interpreted as the phrase "consisting of" unless the context clearly indicates otherwise.

[0034] It should be understood that the expression "at least one of" alone, following a listing of a number of objects, is intended to mean each listed object individually as well as the various combinations of two or more of the listed objects, unless otherwise understood from the context and use. The expression "and / or" in relation to a list of items should be understood to have the same meaning as the expression "consisting of" in relation to the list of items, unless otherwise understood from the context and use.

[0035] The use of the term "include," "includes," "including," "has," "have," "having," "contains," "containing," or "contain," including grammatical equivalents thereof, is generally understood to be open-ended and non-limiting, for example, by permitting additional unspecified elements or steps to be present, unless otherwise stated or understood from the context.

[0036] When the term "about" is used in reference to a quantitative value, the present teachings also include the particular quantitative value itself, unless otherwise specifically stated. As used herein, the term "about" means a variance of ±10% from the nominal value, unless otherwise stated, or inferred from the context.

[0037] At various places in the present specification, values are disclosed in ranges. It is specifically intended that the description include each and every subcombination of the members of the ranges specified. For example, the integers from 0 to 40 are specifically intended to be disclosed individually, as are the integers from 1 to 20. Specifically, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40 are specifically intended to be disclosed individually, as are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20.

[0038] The use of any and all examples, or exemplary language (e.g., "such as" or "including") provided herein, is intended merely to better illuminate the application and does not pose a limitation on the scope of the application unless claimed. No language is such that it will be construed as indicating any non-claimed element as essential to the practice of the application.

[0039] Throughout this specification, where compositions and kits are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are compositions and kits of the present application that do not consist of, or consist essentially of, the specific components, and there are processes and methods of the present application that do not consist of, or consist essentially of, the specific steps.

[0040] As a general matter, unless otherwise indicated, percentages of compositions specified are by weight.

[0041] Photocatalysts are an emerging technology for removing recalcitrant contaminant compounds from water in need of remediation. Technically, the cascade of reactions involved in photocatalysis is initiated by the absorption of a photon, which excites an electron from the valence band to the conduction band of a semiconductor material, thereby creating an electron-hole pair. The electron-hole pair can migrate to the surface of the material, where it reacts with the surrounding water and dissolved oxygen to form reactive oxygen species ("ROS"). It is these ROS that participate in the oxidation of recalcitrant contaminant compounds in solution, resulting in the breakdown of the target contaminant into benign byproducts.

[0042] Photocatalysts with a narrower band gap are advantageous for capturing more visible light photons. Thus, reducing the band gap of a photocatalytic material facilitates more photocatalytic activity for visible light.

[0043] The present teachings can support the rapid remediation of eutrophic water bodies by increasing the availability of dissolved and undissolved oxygen, introducing a viscous polyelectrolyte that precipitates colloidal and attached algae, reducing turbidity and increasing the depth and rate of photosynthesis, releasing active benign chains (reducing COD, which triggers ROS), accelerating the breakdown of heavy hydrocarbons and oils (which in turn makes oxygen available to aerobic bacteria), stimulating dormant microorganisms and / or driving the efficiency of natural biological purification processes (all with minimal intervention and no external artificial energy source). The activity also promotes benign reactions that have a secondary effect of removing and dissolving dense settled organic sludge and releasing it as a digestible food source for the rapidly improved aquatic environment. The photocatalytic composite additionally remediates and reduces the ammonia and hydrogen sulfide components of polluted water, which pose a great hazard to aquaculture.

[0044] Photocatalytic composite The effects described herein can be achieved by introducing a photocatalytic composite comprising Ti02-coated silver ((Ti02) n / Ag) nanocomposite into the water. The (Ti02) n / Ag) nanocomposite is coated with a polyelectrolyte (e.g., chitosan) such that the photocatalytic composite floats or remains suspended near the surface of the water. This photocatalytic composite can hydrolyze the water into nanoscale, creating a conveyor belt of nanometer oxygen bubbles that can remain in the water for days, even in saturated water, gradually dissolving and carrying particles that are newly available as food stock for the natural zoo, fish, and microorganisms that have been suppressed to date.

[0045] In various embodiments, the photocatalytic composite for water remediation comprises Ti02along with Ag and selenium. Specifically, the photocatalytic composite according to the present teachings can include a Ti02 / Ag nanocomposite with a doped structure of Se that provides visible light reactive Ti02nanoparticles. It has a wide photocatalytic range from UV to visible light (e.g., sunlight) and can promote the breakdown of underwater pollutants and pollutant compounds and the oxidation of heavy metals.

[0046] In various implementations, the photocatalytic composite comprises two types of nanocomposites (or "nanoelectrodes"), e.g., Ag and AgCl, to form a Ti02-coated silver nanocomposite ("((Ti02) n / Ag") and a Ti02-coated silver chloride ("((Ti02) n / AgCl) nanocomposites. The photocatalytic composite is coated with a polyelectrolyte (e.g., chitosan) and another polymer. The other polymer can be PVP and / or polyethylene glycol (PEG). Without being bound by any specific theory, it is believed that the other polymer prevents the aggregation or agglomeration of the TiO2-containing nanocomposites, such that their surface area is maximized for visible light and / or sunlight radiation, i.e., maintaining the increased surface area of ​​the TiO2-containing nanocomposites to maximize photocatalytic activity.

[0047] Due to the inclusion of selenium as a dopant, the photocatalytic composite material exhibits a broad photocatalytic activation range from UV to visible light, while also possessing high electron transport potential and electron acceptor properties that promote the decomposition of underwater pollutants and the oxidation of heavy metals. Furthermore, (TiO2) n / Ag nanocomposites and (TiO2) n The combination of / AgCl nanocomposites provides excellent electrical properties for interfacial charge transfer and surface reactions, enabling the materials produced through photocatalytic redox to effectively remove organic nitrogen, phosphorus, and other poorly decomposed pollutants and contaminant compounds. Furthermore, the presence of silver provides the photocatalytic composite material with antimicrobial properties.

[0048] More specifically, in some embodiments, the photocatalytic composite material of this teaching for water remediation typically comprises TiO2, Ag, AgCl, Se, and a polyelectrolyte binder (e.g., a mixture of chitosan and polyvinylpyrrolidone (PVP)). For a schematic diagram of the general chemical structure of the photocatalytic composite material of this teaching, see [link to schematic diagram]. Figure 1A and 1B . Figure 1A (TiO2) associated with polymer 10 and chitosan 20 is shown. n / Ag and (TiO2) n / AgCl nanocomposite colloids.

[0049] Figure 1B Similar to Figure 1A However, it includes Se as a dopant associated with TiO2-containing nanocomposites to promote efficient electron transfer mechanisms. Using these components, TiO2-Ag nanocomposites can be formed together with TiO2-Ag-Se, TiO2-AgCl, and TiO2-AgCl-Se nanocomposites to create doped structures in the preparation of visible-light-reactive TiO2 photocatalyst compositions.

[0050] Depending on the application, the photocatalytic composite can further comprise a noble metal or noble metal such as Au and Pt or a transition metal component such as Ni and Co in addition to Ag and AgCl. It is believed that, as with the Ti02-Ag nanocomposite comprising Se, the additional metal component(s) can be in the form of a nanocomposite having a doped structure.

[0051] The Ti02is generally substantially anatase phase Ti02(e.g., the phase is at least about 80%, at least about 85%, at least about 90%, or at least about 95%, or at least about 99%). The Ti02particles can have an average diameter of about 0.5 nm to about 20 nm.

[0052] In some embodiments, the photocatalytic composite has a Ti02concentration of about 25 mg / L to about 1000 mg / L, about 35 mg / L to about 500 mg / L, or about 50 mg / L to about 200 mg / L. In various embodiments, the photocatalytic composite has a Ti02concentration of from about 100 mg / L to about 500 mg / L, or from about 65 mg / L to about 250 mg / L, or from about 75 mg / L to about 150 mg / L. In some embodiments, the photocatalytic composite has a Ti02concentration of from about 100 mg / L to about 200 mg / L. In particular embodiments, the photocatalytic composite has a Ti02concentration of from about 50 mg / L to about 200 mg / L or to about 250 mg / L or to about 325 mg / L.

[0053] In certain embodiments, the concentration of Ag in the photocatalytic composite is about 5 mg / L to about 35 mg / L, or about 10 mg / L to about 25 mg / L, or about 10 mg / L to about 20 mg / L. In particular embodiments, the concentration of Ag in the photocatalytic composite is about 5 mg / L to about 15 mg / L or to about 25 mg / L.

[0054] In various embodiments, the concentration of AgCl in the photocatalytic composite is about 5 mg / L to about 35 mg / L, or about 10 mg / L to about 25 mg / L, or about 10 mg / L to about 20 mg / L.

[0055] In some embodiments, the concentration of Se in the photocatalytic composite is about 0.1 mg / L to about 3 mg / L, or about 0.2 mg / L to about 1.5 mg / L, or about 0.3 mg / L to about 1 mg / L.

[0056] With respect to the photocatalytic component of the photocatalytic composite, in some embodiments, about 70% to about 90% by weight of the photocatalytic component can be Ti02, with about 10% to about 30% being Ag / Se or Ag / AgCl / Se. In certain embodiments, about 80% of the photocatalytic component can be Ti02, with the remaining 20% being Ag / Se or Ag / AgCl / Se.

[0057] The Ag in the photocatalytic composite generally includes less than about 10% Ag+. In various embodiments, the Ag in the photocatalytic composite includes less than about 20% or less than about 15% Ag+. In some embodiments, the Ag in the photocatalytic composite includes less than about 5% Ag+. The Ag particles can have an average diameter of between about 15 nm and about 75 nm.

[0058] In various embodiments, the photocatalytic composite includes a polyelectrolyte that is a cationic polyelectrolyte. The cationic polyelectrolyte can be a cationic biopolymer, such as chitosan. In some embodiments, (Ti02) n The / Ag particles are coated or encapsulated by the polyelectrolyte and the other polymer, when present.

[0059] For example, the coating can be chitosan and another polymer such as PVP and / or PEG. Chitosan is a polyelectrolyte used as a polymeric flocculant for flocculating suspended solids in water. It is insoluble in water and is prepared by diluting an organic or inorganic acid in a solvent during manufacture. The chitosan or any other cationic polyelectrolyte of the present teachings aggregates by electrostatic neutralization in combination with algal and colloidal matter in water, which are negatively charged materials. The composition reduces turbidity by agglomerating and precipitating the algal and other colloidal matter. In addition, chitosan can keep the agglomerated contaminants close to the photocatalytic species, which can rapidly decompose them into environmentally friendly substances, reducing the toxicity of the water or sludge. In addition, coating the photocatalyst nanocomposite with a floating polymeric electrolyte such as chitosan helps to keep the nanocomposite floating while also attaching to harmful algae to prevent their growth.

[0060] In various embodiments, the photocatalytic composite has a concentration of the polyelectrolyte of from about 0.3 g / L to about 25 g / L, or about 1 g / L to about 20 g / L or to about 15 g / L, or about 5 g / L to about 10 g / L.

[0061] In particular embodiments, the concentration of the other polymer in the photocatalytic composite is about 0.001 g / L to about 25 g / L. In various embodiments, the concentration of the other polymer is about 0.005 g / L to about 20 g / L. In certain embodiments, the concentration of the other polymer is about 0.01 g / L to about 10 g / L. In particular embodiments, the concentration of the other polymer is about 0.01 g / L to about 5 g / L.

[0062] In various embodiments, the photocatalytic composite includes about 0.0005% to about 5% by weight of the polyelectrolyte, based on the total weight of the photocatalytic composite. In some embodiments, the photocatalytic composite can include about 0.01% to about 3% by weight of the polyelectrolyte, based on the total weight of the photocatalytic composite. In certain embodiments, the photocatalytic composite includes about 0.5% to about 2% by weight of the polyelectrolyte, based on the total weight of the photocatalytic composite. In some embodiments, the photocatalytic composite includes about 0.0005% to about 1% by weight of the polyelectrolyte, based on the total weight of the photocatalytic composite. In certain embodiments, the polyelectrolyte is chitosan ((C6H 11 NO4) m ) (here, m represents the symbol system of the polymer structure). More specifically, chitosan is a biopolymer extracted from chitin, the main structural component of crustacean shells, and can be used as a polyelectrolyte and coagulant for aggregating underwater algal blooms and floating bodies. Chitosan material is a polycationic polymer substituted with amino groups in chitin by a chemical deacetylation reaction.

[0063] Acids such as aqueous acetic acid can be used as a solvent for the polyelectrolyte chitosan and can also be used as a dispersant in the water body to provide a localized pH suitable for the formation and effective growth of naturally occurring microorganisms.

[0064] In various embodiments, the solvent includes water, ethylene glycol, methylene glycol, diethylene glycol, an acid, and combinations thereof. In some embodiments, the acid is acetic acid.

[0065] In certain embodiments, the photocatalytic composite includes about 0.001% to about 3% by weight of the acid, based on the total weight of the photocatalytic composite. In some embodiments, the photocatalytic composite includes about 0.01% to about 2% by weight of the acid, based on the total weight of the photocatalytic composite. In particular embodiments, the photocatalytic composite includes about 0.001% to about 1% by weight of the acid, based on the total weight of the photocatalytic composite. In some embodiments, the acid includes or is acetic acid.

[0066] In particular embodiments, the photocatalytic composite has a weight ratio of the polyelectrolyte to the acid in a range of about 10: 1 to about 5:4 or in a range of about 1: 1 to about 4: 1.

[0067] The pH of the photocatalytic composite is generally in a range of about 3 to about 6. In some embodiments, the pH of the photocatalytic composite is in a range of about 4 to about 5.

[0068] The total amount of solvent (e.g., including the "first solvent" and the "second solvent") in the photocatalytic composite for water remediation can be between about 50% to about 99.9% by weight, based on the total weight of the photocatalytic composite. In various embodiments, the photocatalytic composite includes about 70% to about 99.9% by weight of the solvent, based on the total weight of the photocatalytic composite. In some embodiments, the photocatalytic composite includes about 80% to about 99.9% by weight of the solvent, based on the total weight of the photocatalytic composite.

[0069] In some embodiments, the weight ratio of the polyelectrolyte to the nanocomposite (i.e., the metal and the metal oxide) is from about 90 to 130: 1, or about 100 to 120: 1, or about 110: 1. In certain embodiments, the weight ratio of the polyelectrolyte to the other polymer (e.g., chitosan to PVP) is about 7-9: 1, or about 8: 1.

[0070] In particular embodiments, the photocatalytic composite of the present teachings can include between about 0.05 mg / L to about 5 mg / L of copper (Cu), e.g., about 2 mg / L or about 3 mg / L of Cu. While Cu is generally avoided for water remediation, its presence can improve the antifungal and disinfectant properties of the photocatalytic composite if desired.

[0071] In various embodiments, if Ti02 / Cu particles are present, and the concentration of Cu in the photocatalytic composite can be between about 0.5 mg / L to about 5 mg / L. In some embodiments, the amount of Cu in the photocatalytic composite can be about 0.5 mg / L to about 7 mg / L, or about 0.5 mg / L to about 3 mg / L.

[0072] In various embodiments, the photocatalytic composites of the present teachings can include silver, titanium dioxide, chitosan, and a polymer, and optionally selenium, copper, silver chloride, and an acid. For example, in some embodiments, the photocatalytic composite can include about 5 mg / L to about 35 mg / L Ag; about 25 mg / L to about 1000 mg / L Ti02; about 0.3 g / L to about 20 g / L chitosan; and about 0.0001 g / L to about 25 g / L polymer (e.g., PVP and / or PEG); and optionally about 0.1 mg / L to about 3 mg / L Se; about 0.05 mg / L to about 5 mg / L Cu; about 5 mg / L to about 35 mg / L AgCl; and about 0.001% to about 3% by weight of an acid (e.g., acetic acid) based on the total weight of the photocatalytic composite.

[0073] In certain embodiments, the photocatalytic composite can include about 5 mg / L to about 15 mg / L or about 20 mg / L or about 25 mg / L Ag; about 50 mg / L to about 200 gm / L or to about 250 mg / L Ti02; about 5 g / L to about 15 g / L chitosan; and about 0.01 g / L to about 5 g / L polymer (e.g., PVP and / or PEG); and optionally about 0.3 mg to about 1 mg / L Se; about 0.5 mg / L to about 3 mg / L Cu; about 10 mg / L to about 20 mg / L AgCl; and about 0.001% to about 1% by weight of an acid (e.g., acetic acid) based on the total weight of the photocatalytic composite. Of course, the amounts of these components can vary in the photocatalytic composite as described herein.

[0074] In some embodiments, the photocatalytic composite can include Ag (e.g., from about 6 mg / L to about 40 mg / L); Ti02(e.g., from about 100 mg / L to about 360 mg / L); chitosan (e.g., about 0.1 g / L to about 25 g / L); and PVP (e.g., about 300 mg / L to about 2500 mg / L). The photocatalytic composite can include acetic acid (e.g., from about 0.01% to about 0.2%).

[0075] In certain embodiments, the photocatalytic composite can include Ag (e.g., from about 6 mg / L to about 40 mg / L, such as about 10 mg / L to about 30 mg / L), Ti02(e.g., from about 100 mg / L to about 360 mg / L, such as about 100 mg / L to about 200 mg / L, or about 200 mg / L to about 300 mg / L), Se (e.g., from about 0.01 mg / L to about 5 mg / L, such as about 1 mg / L or about 32 mg / mL), and chitosan (e.g., from about 0.1 g / L to about 25 g / L, such as about 1 g / L to about 10 g / L or about 1 g / L to about 15 g / L). In particular embodiments, the photocatalytic composite can include PVP (e.g., from about 0.01 g / L to about 2.5 g / L, such as about 0.1 g / L to about 10 g / L or about 0.1 g / L to about 5 g / L).

[0076] In some embodiments, the photocatalytic composite can include Ag (e.g., from about 10 mg / L to about 30 mg / L), Ti02(e.g., from about 150 mg / L to about 250 mg / L), Se (e.g., from about 0.01 mg / L to about 2 mg / L), chitosan (e.g., from about 5 g / L to about 15 g / L), and PVP (e.g., from about 1 g / L to about 2.5 g / L).

[0077] In various embodiments, the photocatalytic composite can include Ag (e.g., from about 6 mg / L to about 40 mg / L), Ti02(e.g., from about 100 mg / L to about 360 mg / L), Se (e.g., from about 0.01 mg / L to about 5 mg / L), Cu (e.g., from about 0.1 mg / L to about 5 mg / L, such as about 2 mg / L or about 3 mg / L), and chitosan (e.g., from about 0.1 g / L to about 25 g / L). In particular embodiments, the photocatalytic composite can include PVP (e.g., about 300 mg / L to about 2500 mg / L).

[0078] In some embodiments, the photocatalytic composite can include Ag (e.g., from about 10 mg / L to about 30 mg / L), Ti02(e.g., from about 150 mg / L to about 250 mg / L), Se (e.g., from about 0.01 mg / L to about 2 mg / L), Cu (e.g., from about 0.1 mg / L to about 3 mg / L), chitosan (e.g., from about 5 g / L to about 15 g / L), and PVP (e.g., about 1000 mg / L to about 2500 mg / L).

[0079] In particular embodiments, the photocatalytic composite can include Ag (e.g., about 10 mg / L or about 30 mg / L), Ti02(e.g., about 165 mg / L or about 200 mg / L), Se (e.g., about 1 mg / L or about 2 mg / L), Cu (e.g., about 2 mg / L or about 3 mg / L), chitosan (e.g., about 9 g / L or about 13 g / L), and PVP (e.g., about 1000 mg / L or about 1500 mg / L).

[0080] In some embodiments, the photocatalytic composite can include PEG (e.g., from about 300 mg / L to about 2500 mg / L or to about 1500 mg / L or to about 750 mg / L). In certain embodiments, the photocatalytic composite can include PEG (e.g., from about 250 mg / L to about 500 mg / L, such as 250 mg / L or 350 mg / L or 500 mg / L).

[0081] In some embodiments, the photocatalytic composite can include Ti02(e.g., from about 100 mg / L to about 200 mg / L), Ag (from about 5 mg / L to about 15 mg / L), Se (e.g., from about 0.1 mg / L to about 1.5 mg / L), Cu (e.g., from about 0.1 mg / L to about 2.5 mg / L), PVP (from about 300 mg / L to about 750 mg / L or to about 500 mg / L or to about 400 mg / L), PEG (from about 100 mg / L to about 750 mg / L or to about 500 mg / L or to about 400 mg / L or to about 300 mg / L or to about 200 mg / L), and chitosan (e.g., from about 1 g / L to about 25 g / L or to about 20 g / L or to about 15 g / L or to about 10 g / L or to about 5 g / L). In particular embodiments, the photocatalytic composite can also include a small amount of hydrochloric acid, e.g., for initial dissolution of the Ti02particles.

[0082] In various embodiments, the present teachings provide a photocatalytic composite material comprising silver, titanium dioxide, chitosan, and one (another) polymer, and optionally selenium, copper, silver chloride, and an acid. In various embodiments, the present teachings provide a photocatalytic composite material comprising silver, titanium dioxide, selenium, chitosan, and one (another) polymer, and optionally copper, silver chloride, and an acid. In some embodiments, the present teachings provide a photocatalytic composite material comprising silver, titanium dioxide, selenium, copper, chitosan, and one (another) polymer, and optionally silver chloride and an acid. In certain embodiments, the present teachings provide a photocatalytic composite material comprising silver, titanium dioxide, selenium, copper, chitosan, an acid, and a polymer, and optionally silver chloride. In particular embodiments, the present teachings provide a photocatalytic composite material comprising silver, titanium dioxide, selenium, copper, chitosan, an acid, one (another) polymer, and silver chloride. In these embodiments, the above amounts of the various components described herein and elsewhere in this application apply equally herein.

[0083] Method of making a photocatalytic composite In another aspect, the present teachings provide methods of making a photocatalytic composite material. These methods can generally comprise mixing Ti02, Ag (such as AgN03) and another polymer in a first solvent to form a first mixture; exposing the first mixture to a reducing agent until less than about 20% of the Ag is Ag+to form a reduced mixture; mixing a cationic polyelectrolyte (optionally an acid) and other polymer in a second solvent to form a second mixture; and adding the second mixture to the reduced mixture, thereby forming a photocatalytic composite material.

[0084] Compositions for the photocatalytic composite materials of the present teachings can comprise an initial solution comprising Ti02, Ag, another polymer, and a first solvent; and a second solution comprising a polyelectrolyte such as chitosan, other polymer, an optional acid such as acetic acid, and a second solvent. Other components as described herein can be present in the appropriate solvents prior to forming the photocatalytic composite materials of the present teachings.

[0085] exposing the first mixture to ultraviolet (UV) radiation, such as UVC radiation (e.g., about 200 nm), until the amount of Ag present is less than about 15% Ag + , or less than about 10% Ag + , or less than about 5% Ag + The amount of Ag+present can be determined by using UV spectroscopy, for example at a wavelength of about 415 nm to about 430 nm.

[0086] For example, in making a photocatalytic composite, a photocatalyst nanocomposite is mixed in a first solvent comprising another polymer; and the polyelectrolyte, acid, and the other polymer dissolved in a second solvent are mixed together after the first mixture is exposed to a reducing agent to make the photocatalytic composite. The first solvent and the second solvent can comprise one or more of water, polyvinylpyrrolidone (PVP), monoethylene glycol (MEG), diethylene glycol (DEG), acetic acid, and combinations thereof. The first solvent and the second solvent can be the same or different, and can be mixed with distilled water for hydrolysis and / or acid gas reactions.

[0087] The total amount of the first solvent and the second solvent (also referred to herein as "solvents") in the photocatalytic composite for water remediation can be between about 50% to about 99.9% by weight, based on the total weight of the photocatalytic composite. In various embodiments, the photocatalytic composite comprises about 70% to about 99.9% by weight of the first solvent and the second solvent, based on the total weight of the photocatalytic composite. In some embodiments, the photocatalytic composite comprises about 80% to about 99.9% by weight of the first solvent and the second solvent, based on the total weight of the photocatalytic composite.

[0088] In various embodiments, the reducing agent comprises ultraviolet radiation (e.g., UVC radiation, such as 200 nm), microwaves, or a combination thereof. In certain embodiments, the mixture is exposed to a reducing agent until less than about 15% or less than about 10% by weight of the Ag is Ag + .

[0089] In some embodiments, the mixture further comprises mixing Se (e.g., Na2Se04) and / or Cu (e.g., Cu(N03)2-3H20) and / or AgCl in the first solvent.

[0090] Method of using a photocatalytic composite In another aspect, the present teachings provide a method of water remediation, comprising contacting a photocatalytic composite as described herein with a body of water in need of remediation; and exposing the photocatalytic composite to visible light and / or sunlight for a suitable time and under conditions suitable for the photocatalytic composite such that a contaminant compound in the body of water is converted to one or more different compounds. In various embodiments, the body of water is an open body of water. In some embodiments, the body of water is a wetland or a rice field. In certain embodiments, the body of water is an aquaculture farm.

[0091] The photocatalytic composite in liquid form is dispersed on the body of water in an amount depending on the starting conditions of the water, the remediation target, and various other factors. Typically, a high dose of photocatalytic composite, about 5 ppb Ti02(in the amount in the body of water being treated), depending on the particular formulation, is dispersed on the body of water to be treated, which can be poured or sprayed on the area. To homogenize the photocatalytic composite in the water, for example, by using a blower or a rotating boat motor to disperse and mix the photocatalytic composite to speed up the remediation process, a turbulent flow can be created in the water.

[0092] Generally, the target amount of Ti02 / Ag in the water to be remediated is less than about 6 ppb. The target amount of Ti02in the water to be remediated can be less than about 5 ppb and the target amount of Ag can be less than about 0.5 ppb. For water that does not require high level remediation, a lower dose of about 2.5 ppb of Ti02is recommended. Further, depending again on the level of remediation required, lower doses of about 75%, about 50%, about 35%, about 25%, about 20%, about 15%, or about 10% of these amounts can be used.

[0093] If Se is present in the photocatalytic composite, it is typically present in the photocatalytic composite in an amount of about 1.1 ppm or less, for example, about 1.1 ppm, about 1 ppm, about 0.9 ppm, about 0.8 ppm, about 0.7 ppm, about 0.6 ppm, about 0.5 ppm, about 0.4 ppm, about 0.3 ppm, about 0.2 ppm, or about 0.1 ppm. As to the amount present in the water to be treated, Se is present in an amount of about 1.1 ppb or less, for example, about 1.1 ppb, about 1 ppm, about 0.9 ppb, about 0.8 ppb, about 0.7 ppb, about 0.6 ppb, about 0.5 ppb, about 0.4 ppb, about 0.3 ppb, about 0.2 ppb, or about 0.1 ppb.

[0094] The present teachings can describe the amount of "effective material" in a formulation, which is the total concentration of active metal species present in the formulation. For example, in Example 4 below, the effective material totals 162.5 mg / L Ti02+ 10.31 mg / L Ag + 1.84 mg / L Cu + 0.94 mg / L Se, for a total of 175.5 mg / L. The amount of effective material in the formulation is typically about 100 mg / L to about 450 mg / L, or about 100 mg / L to about 350 mg / L, or about 100 mg / L to about 275 mg / L, or about 100 mg / L to about 225 mg / L. The effective amount of the formulation is considered to be 1 ppm, i.e., 1 ppm is the amount of product having a concentration of 175.5 mg / L effective material (175.5 mg / 1000 L). In this example, 1 ppm of product in a lake would be considered to be about.1755 ppb of effective material in the lake (assuming 1 ppm of product is used per 1000 L of lake water). For 2 ppm, the effective material in the lake would be about 0.356 ppb. Typically, the amount of product applied to the body of water is between about 0.5 ppm to about 2 ppm of product, such that the effective material in the lake would be between about 0.05 ppb to about 0.5 ppb, or 0.9 ppb to about 0.4 ppb, or 0.12 ppb to about 0.35 ppb.

[0095] The amounts of the components that contribute to the effective material can be within their ranges as described herein. For example, Ti02is the primary substance or component that contributes to the effective material, e.g., greater than 75%, 80%, 85%, 90%, or 95% of the total effective material. Silver, copper, and selenium can also be included in the effective material in amounts that greatly reduce their amounts. For example, silver can be present in an amount of about 5% to about 10% of the amount of Ti02; copper can be present in an amount of about 0.5% to about 2.5% of the amount of Ti02; and selenium in an amount of about 0.01% to about 1% of the amount of Ti02.

[0096] The photocatalytic composite will diffuse into the water and float on or near the surface of the water. Upon irradiation by sunlight or other visible light, the photocatalytic composite will begin to generate free hydroxyl ions and radicals, which in turn attack the pollutants and polluting compounds in the water to oxidize the undesirable substances, resulting in their breakdown and / or removal. Without wishing to be bound by any particular theory, it is believed that the action of the photocatalytic composite also produces oxygen and hydroxyl ions as microbubbles in the water that contact gases and microorganisms to degas and kill the microorganisms. In addition, the silver present in the photocatalytic composite also acts as an antibacterial agent that helps the cleaning process. In addition, the oxygen produced in the body of water allows for the proliferation of aerobic bacteria.

[0097] Treatment with the photocatalytic composite can be daily, every other day, every third day, every fourth day, every fifth day, every sixth day, once a week, or at less frequent times. Because the duration of floatation of the photocatalytic composite tends to be between about 3 days to about 7 days, twice a week or weekly treatments are a common practice.

[0098] The results of water remediation can be measured by a variety of parameters. For example, the amount of BGA in the water, chlorophyll a in the water (phytoplankton biomass), water transparency, total suspended solids ("TSS") in the water, BOD in the water, pH of the water, total nitrogen in the water, total phosphorus in the water, total nitrogen in the sediment, total phosphorus in the sediment, total organic matter in the sediment, and total organic carbon in the sediment can be measured before and after treatment (including intermediate treatments to monitor progress). These parameters are measured using industry standard analytical techniques, which can include portable equipment for field measurements. For example, a reduction of at least 60% or at least 70% of BGA in the water body can be achieved within about six weeks, with one treatment per week.

[0099] Further, especially for wetlands and rice paddies, the present teachings provide a method of reducing methane emissions during water remediation, comprising contacting the water body with a photocatalytic composite as described herein, and exposing the photocatalytic composite to visible light and / or sunlight for a suitable time, and under conditions suitable for the photocatalytic composite to be able to convert methane into one or more of hydrogen, water, and carbon dioxide.

[0100] Examples Example 1. Production of photocatalytic composite A photocatalytic composite was prepared by mixing 1.5 L PVP dissolved in water (1.8 g / L in water), 100 mL AgN03 dissolved in water (62.8 g / L in water), and 200 mL Ti02 (200 g / L acid water-based anatase Ti02) in 98.2 L distilled water to form a first mixture at room temperature. The first mixture was exposed to UVC radiation of about 200 nm for about 3 hours to provide a reduced mixture.

[0101] Separately, 2500 g chitosan was mixed with 1 L acetic acid and 0.2 L PVP (1.8 g / L) in 98.8 L distilled water to form a second mixture. The second mixture was added to the reduced mixture under stirring at ambient temperature to form the photocatalytic composite.

[0102] During this process, the chitosan and PVP are believed to bind to or encapsulate the Ti02 / Ag nanocomposite to form the final photocatalytic composite in solution.

[0103] Example 2. Water remediation test #1 Water remediation tests were conducted by the NY Center for Clean Water Technology at Stony Brook University to evaluate the remediation of BGA, nitrogen, and phosphorus in water and sedimentation from Lake Agawam, which at the time of testing was designated as the second deepest lake in New York State. The duration of the tests was four weeks.

[0104] Twelve 20 L clear containers were used, four containers were subjected to a low dose of the photocatalytic composite; four containers were subjected to a high dose of the photocatalytic composite, and four containers were designated as controls. To each container, 1000 g of mixed sludge from the lake bottom was added, followed by 10 L of lake water, a fish ball aerator, and three of each of the two types of minnows (6 fish per container).

[0105] The photocatalytic composite of Example 1 was used in this experiment. The photocatalytic composite was dispersed in each container such that the concentration of Ti02 in each container was 5 ppb Ti02 for the high dose and 2.5 ppb Ti02 for the low dose (and the controls received no photocatalytic composite). The same amount was added to each container every week. The containers were exposed to natural light at ambient temperature of outdoor air.

[0106] The hypothesis to be tested was whether the photocatalytic composite was an effective tool for reducing the amount of BGA and regulating natural carbon and nitrogen cycles. The hypothesis was tested by observing the measurements of BGA content in the water, nitrogen content in the water, phosphorus content in the water and sedimentation, total phytoplankton (chlorophyll a) biomass, total suspended solids, biological oxygen demand, and pH.

[0107] These results were successful across all measurements, including a statistically significant reduction in fish mortality.

[0108] More specifically, the reduction in BGA over the course of the 28-day (4-week) test period showed about a 60% reduction in BGA for the low dose treatment and about a 72% reduction in BGA for the high dose treatment compared to the controls.

[0109] Compared to the controls, total phytoplankton biomass (chlorophyll a) was reduced by about 27% with the low dose treatment and more than 37% with the high dose treatment. This result helps to illustrate how the photocatalytic composite can remediate excess nutrients in water by supporting natural remediation cycles, thereby accelerating the consumption of microalgae.

[0110] Compared to the controls, total nitrogen in the water was reduced by about 17% with the low dose treatment and about 28% with the high dose treatment.

[0111] Total phosphorus in the water was reduced by about 28% at the low dose treatment and about 34% at the high dose treatment compared to the control. Phosphorus in the sediment was reduced by about 32% in the low dose treatment and about 44% in the high dose treatment compared to the control. These results demonstrate that the phosphorus remediation to reduce algal blooms and remove organic sediment without dredging. In other words, the photocatalytic composite is not a sequestering agent that encapsulates the phosphorus in sediment, but rather releases excess phosphorus that is trapped in sediment, which accelerates the remediation and reduces total phosphorus.

[0112] Further, the photocatalytic composite can return the water body to a sustainable equilibrium, as evidenced by the change in the pH of the water. After 4 weeks, the pH of the control was about 6.5, while the water that experienced the low dose treatment had a pH of about 6.8, and the water that experienced the high dose treatment was neutral with a pH of about 7.

[0113] Total suspended solids were reduced by about 22% for the low dose treatment and about 33% for the high dose treatment compared to the control. Treatment with the photocatalytic composite rapidly improved the visibility of the water sample, restored the depth or reach of photosynthesis, and reduced harmful algae and sediment.

[0114] The biological oxygen demand (BOD) was reduced by about 8% with the low dose treatment and about 42% with the high dose treatment compared to the control. The reduction in BOD when processing nitrogen and phosphorus is a strong indicator of sustainable lake surface remediation.

[0115] Example 3 - Water remediation test #2 The NY Center for Clean Water Technology at Stony Brook University conducted a medium universe water remediation test to evaluate the remediation of BGA, nitrogen, and phosphorus in water and sediment from Lake Agawam (designated as the second most polluted lake in New York State at the time of the test). The duration of the test was seven weeks.

[0116] Eight 300 L containers were used, four of which were subjected to the high dose of the photocatalytic composite; and four of which were designated as controls. To each container, 7 kg of mixed sludge from the lake bottom was added, followed by 300 L of lake water, and each of two types of baby mint candy (40 fish in each container) (with 10 minnows in the cage for access).

[0117] The photocatalytic composite of Example 1 was used in this experiment. Each container (except the controls) was treated weekly to provide 5 ppb of Ti02product in the test lake water. The containers were exposed to natural light at the ambient temperature of the lake water as the containers were in contact with the lake water at their top.

[0118] The results of the experiment are shown in Table 2, where the rate improvement in multiple parameters for the lake water remediation using the photocatalytic composite of the present teachings was quite significant.

[0119] Table 2 Example 4 - Water remediation, sediment removal and sediment reduction One liter (L) of the photocatalytic composite was prepared at ambient temperature by mixing polyvinylpyrrolidone (PVP) (380 mg) and polyethylene glycol (PEG) (380 mg) with about 987.5 mL of water to provide a mixture A.

[0120] Mixture B was prepared by mixing 2500 mg of Ti02solution (10% dispersion in 25 mL of HC1 (37%) and water), AgN03(25 mg dissolved in 4.975 mL of distilled water), copper nitrate trihydrate (Cu(N03)2-3H20) (10.80 mg dissolved in 4.990 mL of distilled water), and sodium selenate (Na2Se04) (3.16 mg dissolved in 4.997 mL of distilled water) for 24 hours. Mixture A was mixed with mixture B to provide 1 L of mixture C. Mixture C was mixed and exposed to UV radiation until the conversion of Ag+to Ag was about 90% (i.e., less than about 10% Ag + remaining in mixture C).

[0121] Separately, 25 g of chitosan was mixed with 10 mL of acetic acid and 2 mL of PVP (1.8 g PVP / L water) in 988 mL of distilled water to form mixture D.

[0122] 650 mL of mixture C was added to 350 mL of mixture D to form 1 L of the final product, i.e., the photocatalytic composite.

[0123] The amount of effective material considered for the concentration of this formulation was about 175.5 mg / L (i.e., 162.5 mg / L Ti02+ 10.31 mg / L Ag + 1.84 mg / L Cu + 0.94 mg / L Se), which is considered to be 1 ppm or about 0.1755 ppb in lake water. For 2 ppm, the effective material in lake water was about 0.356 ppb.

[0124] A total of 15 ppm of the final material was added to the natural lake over 13 weeks, with 2 ppm added each week for the first three weeks, 1 ppm added each week for the next seven weeks, and then 0.7 ppm added each week for the next three weeks. The lake was approximately four acres in size and ranged in depth from 1 to 13 feet deep. Assuming an average depth of about 7 feet, the total volume of the lake was estimated to be about 28 acre feet or 34,500 cubic meters. Thus, for the first three weeks, 60 L of the final product was added to the lake each week; for the next seven weeks, 30 L of the final product was added to the lake each week; and for the next three weeks, 20 L of the final product was added to the lake each week. (Here, the effective material present in the lake water at about 2 ppm is about 0.31 bbp of the effective material). However, in lake water where the volume of water is not certain, it is difficult to accurately determine the concentration of effective material present.

[0125] The following results occurred together in sediment nutrient removal and water remediation. The data in Table 3 below shows the weekly development of algal diversity during the natural lake treatment.

[0126] Table 3 Over 12 weeks, total algae and BGA decreased, while algal diversity increased.

[0127] The average diversity of different algae is shown in Table 4.

[0128] Table 4 Further, sediment decomposition and sediment depth reduction showed a 50% reduction in total nitrogen, which helped the environment to be more active in the food chain. Measurements were taken at three specific points in the lake, with three samples taken at each point for measurement. Total phosphorous measurements were based on the EPA presulfidation method. Table 5 shows the results of these measurements.

[0129] Table 5 Introduction as a reference This application relates to various published patents, published patent applications, journal articles, and other publications, all of which are incorporated herein by reference. If there is any conflict between any incorporated reference and this specification, the specification takes precedence. Moreover, any particular embodiment of the present disclosure that is disclaimed as prior art can be expressly excluded from any one or more claims. Because such embodiments are considered to be known to those of ordinary skill in the art, they can be excluded even if not expressly disclaimed herein. Any specific embodiment of the present disclosure can be excluded from any claim for any reason, whether or not related to the existence of prior art.

[0130] Equivalency The disclosure can take other specific forms without departing from its spirit or essential characteristics. The foregoing embodiments are therefore to be considered in all respects as illustrative only, and not restrictive of the disclosure described herein. The scope of the disclosure is thus indicated by the appended claims, rather than by the description above, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. A photocatalytic composite material comprising TiO2-coated Ag(TiO2) n TiO2 / Ag particles, wherein the TiO2 / Ag particles associate with the polymer electrolyte in a solvent.

2. The photocatalytic composite material according to claim 1, wherein the (TiO2) n / Ag particles are further combined with another polymer.

3. The photocatalytic composite material according to claim 1 or 2, further comprising selenium (Se).

4. The photocatalytic composite material according to any one of claims 1-3, further comprising TiO2-coated AgCl (TiO2 / AgCl) particles.

5. The photocatalytic composite material according to claim 3 or 4, further comprising TiO2 and Se coated Ag (TiO2 / Ag / Se) particles and TiO2 and Se coated AgCl (TiO2 / AgCl / Se) particles.

6. The photocatalytic composite material according to any one of claims 1-5, wherein the TiO2 substantially comprises anatase TiO2.

7. The photocatalytic composite material according to any one of claims 1-6, wherein the silver (Ag) contains less than about 10% Ag+.

8. The photocatalytic composite material according to any one of claims 1-7, wherein the density of the polyelectrolyte is less than that of water, thereby the photocatalytic composite material floats or remains suspended in water.

9. The photocatalytic composite material according to any one of claims 1-8, wherein the polyelectrolyte is a cationic biopolymer.

10. The photocatalytic composite material according to claim 9, wherein, The cationic biopolymer is chitosan.

11. The photocatalytic composite material according to any one of claims 2-10, wherein another polymer is polyvinylpyrrolidone.

12. The photocatalytic composite material according to any one of claims 1-11, wherein (TiO2) n / Ag particles are coated and / or encapsulated by the polymer electrolyte.

13. The photocatalytic composite material according to any one of claims 2-11, wherein (TiO2) n / Ag particles are coated and / or encapsulated by the polymer electrolyte and other polymers.

14. The photocatalytic composite material according to any one of claims 4-11, wherein the (TiO2) n / Ag particles and the aforementioned (TiO2) n / AgCl particles are coated and / or encapsulated with polyelectrolytes.

15. The photocatalytic composite material according to any one of claims 4-11, wherein (TiO2) n / Ag particles and (TiO2) n / Ag particles are coated and / or encapsulated by the polymer electrolyte and other polymers.

16. The photocatalytic composite material according to any one of claims 1-15, wherein the Ag particles have an average diameter between about 15 nm and about 75 nm.

17. The photocatalytic composite material according to any one of claims 1-16, wherein the TiO2 particles have an average diameter of about 0.5 nm to about 20 nm.

18. The photocatalytic composite material according to claim 17, wherein, Solvents include water, ethylene glycol, methylene glycol, diethylene glycol, and acids.

19. The photocatalytic composite material according to claim 18, wherein, The acid mentioned is acetic acid.

20. The photocatalytic composite material according to any one of claims 1-19, comprising about 0.0005% to about 5% by weight of the polyelectrolyte based on the total weight of the photocatalytic composite material.

21. The photocatalytic composite material according to any one of claims 1-19, comprising about 0.05% to about 2% by weight of the polyelectrolyte based on the total weight of the photocatalytic composite material.

22. The photocatalytic composite material according to any one of claims 1-21, comprising about 50% to about 99.9% by weight of the solvent based on the total weight of the photocatalytic composite material.

23. The photocatalytic composite material according to any one of claims 18-22, comprising about 0.001% to about 3% of acid based on the total weight of the photocatalytic composite material.

24. The photocatalytic composite material according to any one of claims 18-23, wherein the weight ratio of the polyelectrolyte to the acid is in the range of about 10:1 to about 5:

4.

25. The photocatalytic composite material according to any one of claims 1-24, wherein the concentration of the polyelectrolyte is from about 8 g / L to about 20 g / L.

26. The photocatalytic composite material according to any one of claims 1-25, wherein the concentration of TiO2 is about 50 mg / L to about 1000 mg / L.

27. The photocatalytic composite material according to any one of claims 1-26, wherein the concentration of Ag is about 5 mg / L to about 35 mg / L.

28. The photocatalytic composite material according to any one of claims 2-27, wherein the concentration of the other polymer is from about 0.01 g / L to about 5 g / L.

29. The photocatalytic composite material according to any one of claims 3-28, wherein the concentration of Se is from about 0.05 mg / L to about 3 mg / L.

30. The photocatalytic composite material according to any one of claims 3-28, wherein the concentration of Se is from about 0.1 mg / L to about 2 mg / L.

31. The photocatalytic composite material according to any one of claims 1-30, further comprising copper (Cu).

32. The photocatalytic composite material according to claim 31, wherein, The concentration of Cu is from about 0.5 mg / L to about 7 mg / L.

33. The photocatalytic composite material according to claim 31, wherein, The concentration of Cu is from about 0.5 mg / L to about 3 mg / L.

34. A photocatalytic composite material, comprising: silver; Titanium dioxide; Chitosan; as well as Polyvinylpyrrolidone.

35. The photocatalytic composite material according to claim 34, further comprising acetic acid and water.

36. The photocatalytic composite material according to claim 34 or 35, further comprising: One or more of silver chloride, copper, and selenium.

37. A photocatalytic composite material, comprising: silver; Titanium dioxide; selenium; as well as Chitosan.

38. The photocatalytic composite material according to claim 37, further comprising: One or more of copper and polyvinylpyrrolidone.

39. A photocatalytic composite material, comprising: silver; Titanium dioxide; selenium; copper; as well as Chitosan.

40. The photocatalytic composite material according to claim 39, further comprising polyvinylpyrrolidone.

41. A method for manufacturing a photocatalytic composite material, comprising: TiO2, Ag and another polymer are mixed in a first solvent to form a first mixture; The first mixture was exposed to a reducing agent until less than about 20% of the Ag was Ag+ to form a reduced mixture; Cationic polyelectrolytes, acids, and other polymers are mixed in a second solvent to form a second mixture; and The second mixture is added to the reduced mixture to form a photocatalytic composite material.

42. The method according to claim 41, wherein, The mixing further includes mixing Se and / or Cu in the first solvent.

43. The method according to claim 41 or 42, wherein the reducing agent comprises ultraviolet radiation, microwaves, or a combination thereof.

44. The method according to any one of claims 41-43, wherein, Ag+ is defined as less than 10% by weight of Ag.

45. A water remediation method, comprising: The photocatalytic composite material according to any one of claims 1-30 is brought into contact with the water body that needs to be remediated; as well as Expose the photocatalytic composite material to visible light and / or sunlight for a suitable time and under conditions suitable for the photocatalytic composite material to cause pollutant compounds in the water body to be converted into one or more different compounds.

46. ​​The method according to claim 45, wherein, The one or more different compounds are oxidized contaminant compounds.

47. The method according to claim 45, wherein, The water body is an open body of water, wetland, or paddy field.

48. The method according to any one of claims 45-47, wherein oxygen is generated in the water to allow the proliferation of aerobic bacteria.

49. A method for reducing methane emissions during water remediation, comprising: Contact the water with the photocatalytic composite material according to any one of claims 1-40; as well as Expose the photocatalytic composite material to visible light and / or sunlight for a suitable time and under conditions suitable for the photocatalytic composite material to induce the conversion of methane in water into one or more different compounds.

50. The method according to any one of claims 45-49, wherein the method comprises contacting a fresh, unused photocatalytic composite material with water multiple times over a period of time.

51. The method according to any one of claims 45-49 and 50, wherein, The method results in one or more of the following: The reduction of blue-green algae in water bodies; The reduction of total phytoplankton biomass (chlorophyll a) in water bodies; Increased biodiversity in phytoplankton communities; Increased water transparency; The reduction of total suspended solids in water bodies; The decrease in chemical oxygen demand in water bodies; The reduction of total nitrogen in water bodies; The reduction of total phosphorus in water bodies; The total nitrogen that settles in the water body decreases; The reduction of non-organic nitrogen deposited in the water; The reduction of total phosphorus deposited in the water; The reduction in the sedimentation of total organic matter in water bodies; The reduction in total organic carbon deposited in underwater bodies; An increase in the pH of the water body; and The amount of sedimentation in the water body has decreased.

52. The method of claim 51, wherein the pH of the resulting water body is about 7.

53. The method according to any one of claims 45-48 and 50, wherein the water body has algal blooms and / or negatively charged pollutant compounds and photocatalytic composite aggregates of pollutants, thereby reducing the turbidity of the water body.

54. The method according to any one of claims 50-53, wherein, The process involves repeatedly exposing fresh, unused photocatalytic composite material to water once a week for 4 weeks; or once a week for 6 weeks; or twice a week for 4 weeks over a period of time. Alternatively, contact may be made twice a week for 6 weeks; or once or twice a week for more than 6 weeks.

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