Water treatment method and system

Abstract

The present invention relates to a water treatment method and system, the water being an aqueous system containing organic matter, the aqueous system containing chlorine-containing compounds, the method comprising: an electrochemical treatment step and a photochemical treatment step, wherein, in the electrochemical treatment step, the aqueous system flows from the cathode to the anode, the aqueous system passing through the cathode and the anode in the flow direction, and the aqueous system flowing out of the anode generates hypochlorite through an anode electrochemical reaction, in the photochemical treatment step, the aqueous system flowing out of the anode is irradiated with ultraviolet light to generate chlorine radicals in the aqueous system, and the radicals react chemically with the organic matter, and the aqueous system completing the photochemical treatment step is at least partially returned to flow to the cathode in the electrochemical treatment step, at least part of the aqueous system being treated through one or more cycles comprising the electrochemical treatment step and the photochemical treatment step.

Description

Technical Field

[0001] This invention belongs to the field of environmental science and relates to a method and system for purifying water systems containing organic matter and salt. More specifically, this invention relates to a method and system for purifying water systems containing organic matter and salt, especially industrial or domestic wastewater systems. Background Technology

[0002] With industrial development and water scarcity, the concentration and composition of high-salinity organic wastewater (referred to as high-salinity organic wastewater or high-salinity wastewater) generated by some industries are becoming increasingly higher, leading to greater environmental pressure. For example, chemical agents are used in various industries, including pesticides, pharmaceuticals, textiles, papermaking, printing and dyeing, and chemicals, generating large amounts of high-salinity organic wastewater during the production and use of these products.

[0003] High-salt organic wastewater typically contains large amounts of inorganic salts and organic matter. Some literature defines it as wastewater with an organic matter COD value greater than 200 mg / L and dissolved solids (TDS) greater than 3.5%, and the salt content is expressed as the amount of sodium chloride, with a salt mass fraction of not less than 1%.

[0004] High-salinity organic wastewater has long been characterized by high salinity, high COD, strong acidity and alkalinity, high toxicity, complex chemical composition, and poor biodegradability. Because it contains high concentrations of soluble inorganic salts, recalcitrant organic matter, and oils, direct biological treatment and physicochemical treatment methods are costly and often fail to achieve the desired purification results. Furthermore, direct discharge of this wastewater will severely impact soil and water bodies with its soluble inorganic salts and recalcitrant toxic organic matter, causing irreversible environmental damage.

[0005] Reference 1 reviews the treatment technologies for high-salinity organic wastewater, focusing on the research and application status of various processes. High-salinity organic wastewater contains high concentrations of soluble inorganic salts and organic matter, which inhibit the degradation process of microorganisms, affect their growth and metabolism, and cause toxicity. Therefore, physicochemical methods have certain advantages in treating this wastewater. Commonly used physicochemical methods include: electrochemical methods, incineration, evaporation, ion exchange, adsorption, membrane separation, and advanced oxidation methods. In addition, the principle of biological treatment of high-salinity organic wastewater is to utilize halophilic and halophilic bacteria that grow in high-salinity environments. These bacteria use organic pollutants in the wastewater as nutrients for growth and metabolism, converting them into smaller molecules, and even CO2 and H2O, under specific conditions. Although, as mentioned above, high-salinity wastewater inhibits and toxicizes microbial growth and metabolism, significantly reducing the effectiveness of biological methods in treating high-salinity organic wastewater, its low operating cost and lack of secondary pollution make it a key research focus for treating high-salinity organic wastewater.

[0006] Reference 2 discloses a method for treating high-salinity, recalcitrant organic wastewater, specifically involving the application of a triple-effect evaporation + membrane bioreactor + security filtration + reverse osmosis process. Compared with the method using a membrane bioreactor alone, this method is suitable for recalcitrant organic wastewater with higher salinity and can essentially achieve zero wastewater discharge.

[0007] Reference 3 discloses a method for treating high-salt, high-concentration dye wastewater. It employs a plastic sheet (CeO2 / C)-β-PbO2-PTFE electrode as the anode and a steel sheet as the cathode, adding NaCl to the dye wastewater for electrolytic treatment. The synergistic effect of the 20% plastic sheet (CeO2 / C)-β-PbO2-PTFE electrode and chloride ions in treating dye wastewater significantly improves the decolorization rate and COD removal rate.

[0008] In addition, it is known that in some other ultrapure water treatment processes containing urea, there are also schemes that use chlorination reagent in combination with ultraviolet light, such as references 4 and 5.

[0009] Despite numerous studies on wastewater treatment, especially the treatment of high-salt organic wastewater, there is still room for further exploration regarding the effectiveness and economic efficiency of such treatment.

[0010] References:

[0011] Reference 1: Cao Meiling et al., Research progress on treatment of high-salt organic wastewater [J]. Nonferrous Metals Science and Engineering, 2019, 10(3): 92-98.

[0012] Reference 2: CN102267781A

[0013] Reference 3: CN105776449A

[0014] Reference 4: CN114890605A

[0015] Reference 5: CN115925037A Summary of the Invention

[0016] The problem the invention aims to solve

[0017] The biotoxicity and rapid quenching of oxygen-containing free radicals caused by high-salinity environments pose serious challenges to traditional biological methods, ozone treatment, or Fenton treatment of organic pollutants, making the unit cost of organic matter treatment several times or even hundreds of times that of general wastewater. To meet the critical need of the water treatment industry for "synergistic efficiency improvement through pollution reduction and carbon reduction," it is urgent to develop low-carbon treatment technologies for organic pollutants in high-salinity wastewater.

[0018] In extensive industrial practice, it has been found that the scheme in cited reference 2 is still not convenient, and cited reference 3 requires the additional use of chloride salts. Therefore, additional supplementation, control or regulation methods are needed, and the oxidation effect of high-valent chlorine alone is also limited for the removal of many organic substances.

[0019] Furthermore, while references 4 and 5 verify that the combined use of chlorination and ultraviolet light can effectively treat ultrapure water containing urea, they are not suitable for treating high-salt organic wastewater. In addition, in the above references, chlorination and ultraviolet light treatments occur almost simultaneously and in the same location. Therefore, the resulting accumulation of heat effects cannot be considered beneficial to the continuity and stability of industrial production.

[0020] Based on various practices of existing technologies, this invention has discovered that photoelectrochemical technology for dechlorination-enhanced free radical oxidation is an effective means of treating organic matter in high-salt wastewater. It can effectively solve the problems of high energy consumption, low efficiency, and incomplete mineralization of organic matter in existing high-salt wastewater treatment processes.

[0021] Therefore, the present invention provides a method and system for the cyclical treatment of aqueous systems containing organic matter. By creatively coupling an electrochemical treatment unit that can connect the cathode and anode with a photochemical treatment unit using ultraviolet light, organic matter in high-salt wastewater can be effectively removed through one or more cycles of treatment, without the need for additional oxidizing agents.

[0022] Solution for solving the problem

[0023] It has been found that the above-mentioned technical problems can be solved by implementing the following technical solutions:

[0024] [1]. This invention first provides a method for treating an aqueous system containing organic matter, wherein the aqueous system contains chlorine-containing compounds, and the method includes:

[0025] Electrochemical treatment steps and photochemical treatment steps,

[0026] in,

[0027] In the electrochemical treatment step, the aqueous system flows from the cathode towards the anode, penetrating both the cathode and the anode in the flow direction. Furthermore, the aqueous system exiting the anode generates hypochlorite ions via an anodic electrochemical reaction.

[0028] In the photochemical treatment step, the aqueous system flowing out of the anode is irradiated with ultraviolet light to generate chlorine free radicals in the aqueous system. These free radicals then react chemically with the organic matter. After completing the photochemical treatment step, at least a portion of the aqueous system is returned to the cathode in the electrochemical treatment step.

[0029] At least a portion of the aqueous system undergoes one or more cycles of treatment, including electrochemical and photochemical treatment steps.

[0030] [2]. According to the method described in [1], wherein the aqueous system generates monatomic hydrogen via a cathodic electrochemical reaction;

[0031] The aqueous system flowing out of the anode is irradiated with ultraviolet light, thereby generating hydroxyl radicals in the aqueous system, and these radicals also undergo photochemical reactions with the organic matter.

[0032] [3]. The method according to [1] or [2], wherein the anode comprises an oxide of ruthenium; the cathode comprises metallic palladium; and in the electrochemical treatment step, a direct current is applied between the anode and the cathode.

[0033] [4]. The method according to any one of [1] to [3], wherein, in the photochemical treatment step, the ultraviolet light includes one or more types of light with a wavelength of less than 260 nm.

[0034] [5]. The method according to any one of [1] to [4], wherein at least a portion of the chlorine in the aqueous system in which the photochemical treatment step is performed is formed in the form of a non-aromatic organic compound in the form of a covalent bond.

[0035] [6]. The method according to any one of [1] to [5], wherein the aqueous system returned to the cathode in the electrochemical treatment step after the photochemical treatment step is completed is at least partially converted into chloride ions by the cathode.

[0036] [7]. Furthermore, the present invention also provides a treatment system for an aqueous system containing organic matter, wherein the aqueous system contains chlorine-containing compounds.

[0037] The system includes an electrochemical unit, a photochemical unit, a driving unit, and a connecting unit, wherein the connecting unit connects the electrochemical unit, the photochemical unit, and the driving unit.

[0038] The driving unit provides the hydrodynamic force for the aqueous system within the treatment system.

[0039] The electrochemical unit includes a power source, an inlet, an outlet, an anode, and a cathode. The anode and cathode are disposed between the inlet and the outlet and have a fluid-permeable structure. The aqueous system flows from the cathode toward the anode, and in the flow direction, the aqueous system penetrates both the cathode and the anode.

[0040] The photochemical unit includes an inlet, an outlet, and an ultraviolet light source, which irradiates the aqueous system flowing out from the anode of the electrochemical unit.

[0041] Furthermore, the outlet of the photochemical unit is connected to the inlet of the electrochemical unit, so that at least a portion of the aqueous system flowing out of the photochemical unit is returned to the electrochemical unit.

[0042] [8]. According to the system described in [7], the electrochemical unit is configured such that the aqueous system flowing out of the electrochemical unit outlet includes hypochlorite.

[0043] [9]. According to the system described in [8], at least a portion of the hypochlorite ions originate from the electrochemical reaction at the anode of the electrochemical unit; at least a portion of the hydroxide ions originate from the electrochemical reaction at the cathode of the electrochemical unit.

[0044]

[10] . The system according to any one of [7] to [9], wherein in the electrochemical unit, the anode comprises an oxide of ruthenium metal; the cathode comprises palladium metal; and the power source is a direct current power source.

[0045]

[11] . The system according to any one of [7] to

[10] , wherein the photochemical unit is configured to generate chlorine radicals in the aqueous system irradiated by the ultraviolet light source, and optionally also generate hydroxyl radicals.

[0046]

[12] . The system according to any one of [7] to

[11] , wherein the ultraviolet light source in the photochemical unit is configured to provide light including one or more ultraviolet bands with wavelengths below 260 nm.

[0047]

[13] . Furthermore, as some preferred embodiments, the present invention also provides a method for the cyclic treatment of an aqueous system containing organic matter, wherein the aqueous system contains chlorine-containing compounds, wherein the method includes performing one or more cyclic treatments on the aqueous system to be treated using the system described above, each cyclic treatment including sequential treatment of the electrochemical unit and treatment of the photochemical unit.

[0048]

[14] . According to the treatment method described in

[13] , wherein the aqueous system is wastewater containing water-soluble aromatic organic matter.

[0049]

[15] . According to the treatment method of

[13] or

[14] , wherein the aqueous system includes industrial wastewater or domestic wastewater.

[0050] The effects of the invention

[0051] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0052] 1) This invention proposes for the first time an effective means of photoelectrochemical coupling for treating organic matter in high-salt wastewater by enhancing free radical oxidation and decontamination through reduction dechlorination. It can effectively solve the problems of high energy consumption, low efficiency, and incomplete mineralization of organic matter in existing high-salt wastewater treatment processes. Furthermore, compared with traditional electrochemical and ultraviolet chlorination advanced oxidation technologies, the addition of the cathode dehalogenation process in this invention helps to reduce the accumulation of halogenated byproducts and further reduce the toxicity of the effluent.

[0053] 2) This invention creatively designs the anode and cathode in the electrochemical unit as permeable structures. This allows the aqueous system to pass sequentially through the cathode and anode, completing different chemical reactions and imparting specific chemical components (chlorate and optionally hydroxide) to the aqueous system exiting the electrochemical unit. Furthermore, the permeable electrodes and high-speed cyclic operation of this invention, along with the photoelectric spatial separation structure, significantly address the reactor's high energy efficiency and severe heat generation defects in three aspects. First, the permeable electrodes minimize the electrode spacing, facilitating increased mass transfer and reduced internal resistance. Second, the high-speed cyclic operation disrupts the pH microfield on the electrode surface, reducing the voltage between the electrodes and enhancing mass transfer. Finally, the photoelectric spatial separation structure prevents concentrated heat generation within the electrochemical reaction unit, significantly extending electrode life.

[0054] 3) Through a cyclical design, after returning from the photochemical unit to the cathode of the electrochemical unit, chloride ions are regenerated under the action of the cathode reaction, and then hypochlorite ions can be generated again through the anode, thus carrying out electrochemical-photochemical treatment in a cycle. Attached Figure Description

[0055] Figure 1 Schematic diagram of an electrochemical reactor with redox synergy

[0056] Figure 2 This is a scanning electron microscope (SEM) image of the foamed titanium substrate from Example 1.

[0057] Figure 3 This is a transmission electron microscope (TEM) image showing the distribution of palladium clusters on a titanium foam substrate in Example 1.

[0058] Figure 4 Benzoic acid removal rate in Example 2

[0059] Figure 5 The removal efficiency of each organic compound in Example 3

[0060] Explanation of reference numerals in the attached figures:

[0061] 1-254nm UV lamp tube

[0062] 2—Peristaltic pump (drive unit)

[0063] 3—Penetrating reactor shell

[0064] 4—Porous foam palladium-titanium cathode

[0065] 5—Porous foam palladium-titanium anode

[0066] 6—DC power supply

[0067] a—Electrochemical Unit

[0068] b—Photochemical unit Detailed Implementation

[0069] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0070] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0071] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0072] In this specification, the terms "substantially" or "truly" mean that the error is less than 1%, or less than 0.8%, or less than 0.6% compared to the relevant perfect or theoretical standard. Furthermore, when "all" or "entire" is used in this specification, it also means "all" or "entire" in the sense of "substantially" or "truly".

[0073] Unless otherwise specified, "%" in this instruction manual refers to the percentage content by mass.

[0074] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0075] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, or may occur in any of the circumstances described, and the description includes both the occurrence and non-occurrence of the event.

[0076] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0077] In this specification, the terms “comprising” and / or “including” are used to indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0078] In this instruction manual, "normal temperature" or "room temperature" refers to an indoor ambient temperature of "23±2℃".

[0079] In this specification, the term "flow direction" refers to the cyclic flow direction of the aqueous system from the electrochemical unit to the photochemical unit and (at least partially) back to the electrochemical unit. In the electrochemical unit, the flow direction is the direction of flow from the cathode toward the anode.

[0080] This invention primarily provides a method and system for the recyclable treatment of aqueous systems containing organic matter, wherein the aqueous system also contains chlorine-containing compounds. This invention is mainly based on the following insights.

[0081] Ultraviolet irradiation can generate free radicals, which can react with target organic matter to mineralize or inorganicate it. It has been found that further dechlorination can accelerate this transformation, resulting in more thorough treatment of the target organic matter. Based on this strategy, this invention creatively designs an electrochemical unit with fluid-permeable anode and cathode, allowing an aqueous system to flow from the cathode towards the anode. Dechlorination can then be achieved at the cathode, and chlorine is at least partially oxidized to hypochlorite at the anode, which then flows to the photochemical unit for coupling treatment.

[0082] <First Aspect>

[0083] In a first aspect of the present invention, a method for treating an aqueous system containing organic matter is provided, the method comprising sequentially performing electrochemical treatment and photochemical treatment steps, preferably, performing the above-mentioned cyclic treatment once or multiple times.

[0084] Aquifer

[0085] The aqueous system of the present invention is mainly an aqueous system containing organic matter and a certain amount of inorganic salts. In some specific embodiments, the aqueous system contains organic matter and at least 3.5% by mass of total dissolved solids (TDS).

[0086] In some other specific embodiments, the organic matter in the aqueous system is preferably an organic matter with an aromatic structure, such as one or more aryl groups, such as phenyl, heterocyclic aryl, etc. Furthermore, in some preferred embodiments of the invention, the organic matter can be an organic matter with a certain degree of solubility, for example, having a solubility of 1% by mass or more, preferably 2% by mass or more, in water at 80°C under normal pressure. In some preferred embodiments, the organic matter includes aryl fatty acids or their salts, typically, one or more of benzoic acid, benzoate, phenol, bisphenol A, or derivatives thereof.

[0087] Furthermore, the aqueous system of the present invention also contains chlorine-containing compounds, preferably inorganic salts containing chloride ions. In some preferred embodiments of the present invention, the amount of the chlorine-containing compounds in the aqueous system of the present invention is 1% by mass or more, preferably 1.5% by mass or more, and more preferably 3% by mass or more, calculated as sodium chloride (based on the chlorine-containing compounds).

[0088] Furthermore, there are no special requirements in principle regarding the COD value of the aqueous system of this invention, as it is related to its source. In some specific embodiments of this invention, the organic matter content in the aqueous system is such that the COD value is greater than 10,000 mg / L.

[0089] Furthermore, there are no particular restrictions on the source of the water-containing system of the present invention in principle. For example, it can be domestic or industrial wastewater. In some specific embodiments, it can be wastewater that has been used for domestic or production purposes, or it can be wastewater discharged during the production process of certain industrial sectors, such as saponin wastewater, oil extraction wastewater, and wastewater discharged from the printing and dyeing, papermaking, pharmaceutical, chemical, dairy processing, and pesticide industries.

[0090] Electrochemical treatment steps

[0091] The electrochemical treatment step of the present invention mainly involves electrochemically treating the aqueous system in the flow direction of the aqueous system.

[0092] Specifically, the aqueous system flows sequentially through the cathode region and the anode region. Furthermore, in order to improve the reaction efficiency of the cathode reaction and the anode reaction, the aqueous system penetrates both the cathode and the anode in the flow direction.

[0093] For an aqueous system flowing through the anode, under the electrochemical action of the anode, chlorine-containing compounds, especially chlorine in chlorine-containing inorganic salts, are at least partially or completely oxidized, eventually forming hypochlorite.

[0094] In the aqueous system flowing through the cathode, the chlorine is at least partially or completely reduced to negatively valence chlorine, especially chloride ions. This chlorine can be a product of the reaction between chlorine radicals and the target organic matter in the photochemical treatment steps described below, i.e., a dechlorination reaction has occurred. Furthermore, in the aqueous system passing through the cathode, monatomic hydrogen can be generated under the cathodic electrochemical reaction, and the generation of this monatomic hydrogen can also promote the aforementioned dechlorination reaction.

[0095] There are no particular restrictions in principle on the voltage and current present between the cathode and anode in the electrochemical treatment step. In some specific implementations, a direct current can be passed between the cathode and anode, and the current density of such a direct current can be 20–50 mA / cm². 2 For example, 30mA / cm 2 35mA / cm 2 40mA / cm 2 45mA / cm 2 Such voltages can range from 2 to 8V, for example, 3, 4, 5, 6, 7V, etc.

[0096] Therefore, the aqueous system after the electrochemical treatment step contains hypochlorite ions and optionally hydroxide ions after leaving the anode in the flow direction. In some specific embodiments of the present invention, the concentration of hypochlorite ions, calculated as sodium hypochlorite, in the aqueous system leaving the anode can be 50-500 mg / L, for example, 80 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 250 mg / L, 300 mg / L, 350 mg / L, 400 mg / L, 450 mg / L, etc.

[0097] Photochemical treatment steps

[0098] In this invention, the aqueous system that has undergone electrochemical treatment is further subjected to photochemical treatment in the flow direction of the aqueous system.

[0099] The photochemical treatment step can be completed under ultraviolet irradiation. During this process, chlorine elements originating from the electrochemical treatment step, as well as any hydroxyl radicals present, are transformed into chlorine free radicals under the influence of radiation. Hydroxyl free radicals are also generated simultaneously. These free radicals can then react with organic matter in the aqueous system, thereby achieving the mineralization or inorganication of these organic compounds.

[0100] Furthermore, there are no particular restrictions on the ultraviolet light used in the photochemical treatment step. Light in the ultraviolet band commonly used in the art can be used. In some specific embodiments, the ultraviolet light can be one or more types of light with wavelengths below 260 nm. More preferably, a combination of ultraviolet light with a wavelength below 200 nm and ultraviolet light with a wavelength greater than 200 nm but below 260 nm can be used. For the ultraviolet light of the present invention, examples include using one or a combination of two of ultraviolet light with a wavelength of 254 nm and ultraviolet light with a wavelength of 185 nm.

[0101] In the aqueous system that has undergone the above photochemical treatment, the organic matter therein is mineralized or inorganicated by reacting with free radicals in the presence of ultraviolet light. In this process, at least some of the organic matter is degraded into non-aromatic organic matter or even inorganic matter through reactions such as oxidation, addition or substitution.

[0102] In the aqueous system treated by photochemical methods in this invention, the content of the target organic matter is significantly reduced. In some specific embodiments, the content of the target organic matter is reduced by more than 70% by mass, preferably by more than 80% or 90% by mass, or even substantially eliminated.

[0103] Steps of cyclic processing

[0104] In this invention, the aqueous system that has been photochemically treated can be returned at least partially or entirely to the electrochemical treatment step, that is, partially or entirely returned to the cathode, and in the flow direction, undergo an electrochemical treatment step that includes cathode treatment and anode treatment.

[0105] Furthermore, for the aqueous system returned to the cathode region, at least some, or even all, of the covalently bonded chlorine elements are converted into chloride ions through the electrode reaction at the cathode.

[0106] Therefore, the above-described processing procedure of the present invention can perform cyclic processing on the aqueous system. For one cycle, it can include one electrochemical treatment step and one photochemical treatment step.

[0107] For the treatment process of the aqueous system of the present invention, it may include one or more of the above-mentioned cyclic treatments until the content of the target organic matter therein reaches the set or required standard.

[0108] Water system treatment methods

[0109] The present invention also provides a method for treating a water system, wherein the water system can be transformed into the water-containing system described above after undergoing any physical or chemical process.

[0110] In addition to the water system treatment method described in this invention, the water system treatment method may optionally include other water treatment steps, such as filtration, incineration, evaporation, ion exchange, adsorption, membrane separation, etc.

[0111] <Second aspect>

[0112] In a second aspect, the invention relates to a treatment system for the aforementioned aqueous system, which can significantly reduce or completely eliminate target organic matter in the aqueous system. In particular, the treatment system of the present invention can be used to perform the treatment method described in the first aspect.

[0113] Specifically, the system of the present invention includes an electrochemical unit, a photochemical unit, a driving unit, and a connecting unit, wherein the connecting unit connects the electrochemical unit, the photochemical unit, and the driving unit.

[0114] Electrochemical Unit

[0115] The electrochemical unit of the present invention is used to perform an electrochemical treatment step on an aqueous system, preferably the electrochemical treatment step described in the first aspect.

[0116] The electrochemical unit of the present invention necessarily includes a power source, an inlet, an outlet, an anode, and a cathode.

[0117] Preferably, the power supply is a DC power supply, and in some specific embodiments, such a power supply is configured to provide 20–50 mA / cm². 2 The current density.

[0118] The inlet and outlet can be configured as two ports within the external container of the electrochemical unit for the aqueous system to enter and exit. There are no particular restrictions on the specific configuration of these inlet and outlet; it depends on the shape of the container.

[0119] The cathode and anode of the present invention can be disposed inside the container, and preferably, the cathode and anode are configured such that the entire aqueous system flows through the cathode before flowing through the anode. Therefore, in the present invention, the cathode and anode are configured to have a through-structure, so that the aqueous system can pass through the cathode and anode in the flow direction.

[0120] There are no particular limitations on the cathode and anode having a through-hole structure in principle. For example, they can have a multi-layered stacked structure, a comb-like structure, a porous honeycomb structure, a mesh structure, a sponge structure, or a foam structure that extends along the flow direction. In some specific embodiments of the present invention, the through-hole structure is a sponge structure or a foam structure.

[0121] In addition, there are no particular restrictions on the overall external shape of the cathode and anode; for example, they can be flat, cylindrical, or cubic.

[0122] Regarding the cathode material, in principle, there are no special requirements as long as it can achieve the reduction of covalently bonded organochlorine compounds. In some preferred embodiments of the present invention, the cathode can have palladium as the electrode material. In some typical solutions, a palladium layer can be formed on the surface of a conductive substrate to obtain the cathode of the present invention. Preferably, the conductive substrate is cleaned and activated before the palladium layer is formed. Optionally, the palladium layer can be subjected to oxygen-free calcination after its formation. In some specific embodiments of the present invention, such a palladium layer can be formed by sputter deposition. Furthermore, there are no particular limitations on the conductive substrate; considering conductivity, durability, and chemical resistance, it is typically made of titanium.

[0123] In some preferred embodiments of the present invention, the cathode of the present invention can be prepared by the following steps:

[0124] Step 1: Using a porous foam titanium electrode as a substrate, the porous foam titanium electrode is first ultrasonically cleaned with deionized water and acetone to remove surface stains, then chemically polished in a mixed solution of V hydrofluoric acid: V nitric acid: V water = 1:3:6, and then dried in an oven for later use.

[0125] Step 2: Using magnetron sputtering, palladium metal is loaded onto the surface of porous titanium foam to sputter a palladium nanolayer of a certain thickness.

[0126] Step 3: Calcine at 250°C for 1 hour in an argon-hydrogen mixed gas atmosphere with a hydrogen content of 10%.

[0127] Step 4: Calcine at 450°C for 2 hours in a nitrogen atmosphere.

[0128] Regarding the anode material, in principle, there are no special requirements as long as it can oxidize chlorine atoms to a positive valence state. In some preferred embodiments of the present invention, the anode can have ruthenium oxide as the electrode material. In some typical embodiments, the anode of the present invention can be obtained by forming a ruthenium oxide layer on the surface of a conductive substrate layer. Preferably, the conductive substrate layer is cleaned, activated, etc., before forming the ruthenium oxide layer. In some specific embodiments of the present invention, such a ruthenium oxide layer can be formed by a solution-co-precipitation-deposition-calcination process using water-soluble ruthenium salts. Furthermore, there are no particular limitations on the conductive substrate layer; considering conductivity, durability, and chemical resistance, it is typically made of titanium.

[0129] In some preferred embodiments of the present invention, the anode of the present invention can be prepared by the following steps:

[0130] Step 1: Using a porous foam titanium electrode as a substrate, the porous foam titanium electrode is first ultrasonically cleaned with deionized water and acetone to remove surface stains, then chemically polished in a mixed solution of V hydrofluoric acid: V nitric acid: V water = 1:3:6, and then dried in an oven for later use.

[0131] Step 2: Prepare the coating solution: Use hydrated ruthenium trichloride, calculate the amount of RuCl3·xH2O to be used, add RuCl3·xH2O to the isopropanol solution, and then add various solutions in different proportions as needed to prepare the solution. Sonicate for 20 minutes to dissolve.

[0132] Step 3: Then, the polished porous titanium foam is immersed in the prepared precursor solution, dried, and calcined in a muffle furnace at 400°C for 5 minutes. This process is repeated 10 times.

[0133] Step 4: Finally, anneal in a muffle furnace at 450°C for 2 hours.

[0134] Furthermore, regarding the arrangement of the cathode and anode of the present invention, in some preferred embodiments of the present invention, the cathode and anode can be arranged in parallel opposite each other. In principle, there is no particular limitation on the distance between them. In some specific embodiments, from the perspective of resistance control, it can be 1 to 20 mm, for example, 3 mm, 5 mm, 7 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, etc.

[0135] In this invention, by setting the above-mentioned electrodes in the flow direction of the aqueous system, the aqueous system can be sequentially processed by cathodic electrochemical reaction and anodic electrochemical reaction in a flowing manner. Furthermore, since the aqueous system is flowing, unnecessary resistance caused by concentration polarization on the electrode surface can be reduced, thereby improving the processing efficiency of the electrochemical unit of this invention.

[0136] The aqueous system exiting the anode of the electrochemical unit contains hypochlorite ions in the flow direction. In some specific embodiments of the present invention, the concentration of hypochlorite ions, calculated as sodium hypochlorite, in the aqueous system exiting the anode can be 50–500 mg / L, for example, 80 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 250 mg / L, 300 mg / L, 350 mg / L, 400 mg / L, 450 mg / L, etc.

[0137] Photochemical unit

[0138] The photochemical unit of the present invention is mainly used to irradiate an aqueous system, especially an aqueous system that has flowed out of the above-mentioned electrochemical unit, with ultraviolet light. As a result, chlorine free radicals are generated in the aqueous system, and optionally hydroxyl free radicals are also generated.

[0139] In some specific embodiments, the photochemical unit of the present invention may include a housing, an inlet, an outlet, and an ultraviolet light source.

[0140] The containment section is designed to accommodate the flowing aqueous system and provide a site for ultraviolet light irradiation. It also serves as an inlet and outlet for introducing and discharging the aqueous system.

[0141] In principle, there are no particular limitations on the ultraviolet light source of this invention. Light sources in the ultraviolet band commonly used in the art can be used. In some specific embodiments, the ultraviolet light source can emit one or more light with wavelengths below 260 nm. More preferably, it can be a combination of an ultraviolet light source emitting wavelengths below 200 nm and an ultraviolet light source emitting wavelengths greater than 200 nm but below 260 nm. Typically, the ultraviolet light source of this invention includes combinations of two ultraviolet light sources emitting wavelengths of 254 nm and 185 nm.

[0142] Furthermore, in the aqueous system that has passed through the photochemical unit, the target organic matter undergoes a chemical reaction with free radicals, resulting in its transformation. Therefore, in the aqueous system after this unit, the content of the target organic matter is significantly reduced. In some specific embodiments, the content of the target organic matter is reduced by more than 70% by mass, preferably by more than 80% or 90% by mass, or even substantially eliminated entirely.

[0143] Regarding the above-mentioned transformation results of the target organic matter, at least a portion of the target organic matter is converted into non-aromatic organochlorides or even inorganic chlorides.

[0144] Furthermore, the aqueous system flowing out of the photochemical unit outlet can be at least partially returned to the electrochemical unit and recycled back into the electrochemical unit from the electrochemical unit inlet.

[0145] Thus, the electrochemical unit and photochemical unit of the present invention can be connected in series to form a cyclic treatment of the water-containing system.

[0146] Drive unit and connection unit

[0147] The driving unit of the present invention is mainly used to provide the flow force of the aqueous system in the flow direction.

[0148] There are no particular limitations on the specific arrangement of the drive unit of the present invention, and commonly used pump devices in the art, such as peristaltic pumps, can be used. Furthermore, in some preferred embodiments of the present invention, at least one pump / peristaltic pump can be provided between the outlet of the electrochemical unit and the inlet of the photochemical unit to provide the aforementioned flow force.

[0149] Furthermore, the connection unit of the present invention provides communication between the various units described above. Such a unit can be a connecting pipe or conduit. And, if necessary, a switch, valve, or flow divider can be provided.

[0150] Other units

[0151] Other auxiliary units can be used in the system described above in this invention, and there are no particular restrictions in principle. These auxiliary units may include one or more of the following: flow control unit, substance detection unit, system pressure and control unit, temperature control unit, etc.

[0152] Figure 1 Typical examples

[0153] The system described above in this invention, Figure 1 A specific, typical example is given. Box a shows the electrochemical unit, and box b shows the photochemical unit. Arrows indicate the flow direction, and 2 represents a peristaltic pump to provide the power for the flow in the aqueous system.

[0154] like Figure 1 As shown, when the aqueous system flows, it penetrates the cathode 4 and the anode 5, and a DC voltage is applied between the cathode and the anode through a DC power supply. The cathode 4 is a porous foamed palladium-titanium cathode, and the anode 5 is a porous foamed ruthenium-titanium anode. Furthermore, the cathode 4 and the anode 5 are disposed within the housing 3.

[0155] The aqueous system treated by the electrochemical unit further enters the photochemical unit and is treated under the irradiation of a 254nm ultraviolet lamp 1. Finally, all the aqueous system flowing out of the photochemical unit is guided back to the electrochemical unit (cathode).

[0156] Example

[0157] The embodiments of the present invention will be described in detail below with reference to the examples. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0158] Example 1

[0159] (Preparation of porous foamed titanium ruthenium anode and porous foamed palladium titanium cathode, and construction of a through-hole electrochemical reactor)

[0160] The porous titanium-ruthenium electrode (anode) is prepared by the following method:

[0161] Step 1: Using a porous foam titanium electrode as a substrate, the porous foam titanium electrode is first ultrasonically cleaned with deionized water and acetone to remove surface stains, then chemically polished in a mixed solution of V hydrofluoric acid: V nitric acid: V water = 1:3:6, and then dried in an oven for later use.

[0162] Step 2: Prepare the coating solution: Using hydrated ruthenium trichloride, calculate the required amount of RuCl3·xH2O and add it to the isopropanol solution. Subsequently, add various solutions in different proportions as needed to prepare the solution. The prepared ruthenium trichloride solution should be 0.1 mol / L. Dissolve the solution by sonication for 20 minutes.

[0163] Step 3: Then, the polished porous titanium foam is immersed in the prepared precursor solution. After being kept in the precursor solution for 1 minute, it is taken out and dried in an oven for 10 minutes. After drying, it is calcined in a muffle furnace at 400°C for 5 minutes, with the heating rate set to 5°C per minute. This process is repeated 10 times.

[0164] Step 4: Anneal in a muffle furnace at 450℃ for 2 hours to complete the preparation.

[0165] The porous foamed palladium-titanium electrode (cathode) is prepared by the following method:

[0166] Step 1: Using a porous foam titanium electrode as a substrate, the porous foam titanium electrode is first ultrasonically cleaned with deionized water and acetone to remove surface stains, then chemically polished in a mixed solution of V hydrofluoric acid: V nitric acid: V water = 1:3:6, and then dried in an oven for later use.

[0167] Step 2: Palladium metal is loaded onto the surface of porous titanium foam by magnetron sputtering, with a sputtering thickness of 30 nm.

[0168] Step 3: Calcine at 250°C for 1 hour in an argon-hydrogen mixed gas atmosphere with a hydrogen content of 10%, with a heating rate of 5°C per minute.

[0169] Step 4: Calcine at 450°C for 2 hours in a nitrogen atmosphere, with a heating rate of 5°C per minute.

[0170] A porous foamed titanium-ruthenium anode and a porous foamed palladium-titanium cathode are installed in the electrochemical reaction zone. The two electrodes are located between the fluid inlet and the fluid outlet and are connected to the power supply via conductive titanium sheets. A 254nm ultraviolet lamp is inserted into the ultraviolet irradiation zone for ultraviolet irradiation. After assembling the above-mentioned penetration-type photoelectrochemical reactor device, organic wastewater with benzoic acid as the target pollutant is injected into the ultraviolet lamp container. The entire reactor is driven by a peristaltic pump to move the solution from the ultraviolet lamp irradiation zone, through the cathode, through the anode, and finally back to the ultraviolet lamp irradiation zone, thus operating in a cycle.

[0171] Example 2

[0172] The reactor described in Example 1 was used for the efficient removal of benzoic acid from a high-salt system. The implementation steps are as follows:

[0173] Step 1: Set the initial experimental solution to 170 mL, containing benzoic acid at a concentration of 50 ppm and NaCl at a concentration of 0.5 mol.

[0174] Step 2: Set the DC power supply to a constant current of 140mA;

[0175] Step 3: Sampling points were set at 0 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, and 40 min. Ultraviolet irradiation was continuously carried out during the experiment, and 1 mL of solution was taken from the ultraviolet lamp container as the test solution.

[0176] Step 4: Filter the extracted test solution through a 0.22-micron aqueous filter membrane and place it into a liquid chromatography vial for testing;

[0177] Step 5: Analyze the benzoic acid degradation concentration of the prepared sample by high performance liquid chromatography, with the ultraviolet detector wavelength set to 228 nm;

[0178] Step 6: After each experiment, rinse the permeation electrochemical reactor and electrodes multiple times with deionized water.

[0179] Each experiment was repeated three times.

[0180] like Figure 4As shown, benzoic acid was removed within 20 minutes, demonstrating that the photoelectrochemical reactor for dechlorination-enhanced free radical oxidation and decontamination, through anodic chlorination combined with ultraviolet irradiation to stably output ·OH and Cl· free radicals, and synergistic cathodic dechlorination-enhanced free radical oxidation and decontamination, improves the mineralization efficiency of organic matter in high-salt wastewater.

[0181] Example 3

[0182] The reactor described in Example 1 was used for the efficient removal of different organic compounds from a high-salt system. The implementation steps are as follows:

[0183] Step 1: Set the initial experimental solution to 170 mL, with the organic compounds phenol, p-nitrophenol, and bisphenol A all at 100 ppm, and NaCl at 0.5 mol;

[0184] Step 2: Set the DC power supply to a constant current of 140mA;

[0185] Step 3: Sampling points were set at 0 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min. Ultraviolet irradiation was continuously carried out during the experiment, and 1 mL of solution was taken from the ultraviolet lamp container as the test solution.

[0186] Step 4: Filter the extracted test solution through a 0.22-micron aqueous filter membrane and place it into a liquid chromatography vial for testing;

[0187] Step 5: Analyze the benzoic acid degradation concentration of the prepared sample by high performance liquid chromatography, with the ultraviolet detector wavelength set to 228 nm;

[0188] Step 6: After each experiment, rinse the permeation electrochemical reactor and electrodes multiple times with deionized water.

[0189] Each experiment was repeated three times.

[0190] like Figure 5 As shown, all organic compounds can be removed within 40 minutes, further demonstrating that the photoelectrochemical reactor for dechlorination-enhanced free radical oxidation and decontamination improves the mineralization efficiency of organic compounds in high-salt wastewater by using anodic chlorination combined with stable output of ·OH and Cl· free radicals through ultraviolet irradiation, and synergistic cathodic dechlorination-enhanced free radical oxidation and decontamination.

[0191] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0192] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for treating an aqueous system containing organic matter, characterized in that, The aqueous system contains chlorine-containing compounds, and the method includes: Electrochemical treatment steps and photochemical treatment steps, The aqueous system contains chlorine-containing compounds, including inorganic salts with chloride ions, and the amount of chlorine-containing compounds in the aqueous system, converted to sodium chloride, is 1% by mass or more. In the electrochemical treatment step, the aqueous system flows from the cathode towards the anode, penetrating both the cathode and the anode in the flow direction. Furthermore, the aqueous system exiting the anode generates hypochlorite ions via an anodic electrochemical reaction. In the photochemical treatment step, the aqueous system flowing out of the anode is irradiated with ultraviolet light to generate chlorine free radicals in the aqueous system. These free radicals then react chemically with the organic matter. Furthermore, the aqueous system that has completed the photochemical treatment step is at least partially returned to the cathode in the electrochemical treatment step. At least a portion of the aqueous system undergoes one or more cycles of treatment, including electrochemical and photochemical treatment steps; After completing the photochemical treatment step, the aqueous system returned to the cathode in the electrochemical treatment step undergoes at least partial conversion of chlorine elements into chloride ions under the action of the cathode.

2. The method according to claim 1, characterized in that, The aqueous system generates monatomic hydrogen via a cathodic electrochemical reaction; The aqueous system flowing out of the anode is irradiated with ultraviolet light, thereby generating hydroxyl radicals in the aqueous system, and these radicals also undergo photochemical reactions with the organic matter.

3. The method according to claim 1 or 2, characterized in that, The anode comprises ruthenium oxide; the cathode comprises palladium; and in the electrochemical treatment step, a direct current is applied between the anode and the cathode.

4. The method according to claim 1 or 2, characterized in that, In the photochemical treatment step, the ultraviolet light includes one or more types of light with wavelengths below 260 nm.

5. The method according to claim 1 or 2, characterized in that, In the aqueous system that completes the photochemical treatment step, at least a portion of the chlorine element forms non-aromatic organic compounds in the form of covalent bonds.

6. A treatment system for an aqueous system containing organic matter, characterized in that, The aqueous system contains chlorine-containing compounds, and the amount of these compounds, converted to sodium chloride, is 1% by mass or more. The system includes an electrochemical unit, a photochemical unit, a driving unit, and a connecting unit, wherein the connecting unit connects the electrochemical unit, the photochemical unit, and the driving unit. The driving unit provides the hydrodynamic force for the aqueous system within the treatment system. The electrochemical unit includes a power source, an inlet, an outlet, an anode, and a cathode. The anode and cathode are disposed between the inlet and the outlet and have a fluid-permeable structure. The aqueous system flows from the cathode toward the anode in the flow direction, penetrating both the cathode and the anode. Furthermore, the electrochemical unit is configured such that the aqueous system exiting the electrochemical unit outlet includes hypochlorite ions. The photochemical unit includes an inlet, an outlet, and an ultraviolet light source, which irradiates the aqueous system flowing out from the anode of the electrochemical unit. Furthermore, the outlet of the photochemical unit is connected to the inlet of the electrochemical unit, so that at least a portion of the aqueous system flowing out of the photochemical unit is returned to the electrochemical unit, and the processing system is configured to cause at least a portion of the chlorine in the aqueous system returned to the cathode in the electrochemical unit to be converted into chloride ions under the action of the cathode.

7. The system according to claim 6, characterized in that, At least a portion of the hypochlorite ions originate from the electrochemical reaction at the anode of the electrochemical unit.

8. The system according to claim 6 or 7, characterized in that, In the electrochemical unit, the anode comprises an oxide of ruthenium; the cathode comprises palladium; and the power source is a direct current power source.

9. The system according to claim 6 or 7, characterized in that, The photochemical unit is configured to generate chlorine radicals in the aqueous system irradiated by the ultraviolet light source, and optionally also generate hydroxyl radicals.

10. The system according to claim 6 or 7, characterized in that, The ultraviolet light source in the photochemical unit is configured to provide light in one or more ultraviolet bands with wavelengths below 260 nm.

11. A method for recycling an aqueous system containing organic matter, characterized in that, The aqueous system contains chlorine-containing compounds, and the method includes performing one or more cyclic treatments on the aqueous system to be treated using the system according to any one of claims 6 to 10, each cyclic treatment including sequential treatment of the electrochemical unit and treatment of the photochemical unit.

12. The processing method according to claim 11, characterized in that, The aqueous system is wastewater containing water-soluble aromatic organic compounds.

13. The processing method according to claim 11 or 12, characterized in that, The water-containing system includes industrial wastewater or domestic wastewater.

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