Method for preparing active water by liquid discharge plasma cathode with separate preparation of liquid anode and liquid cathode

Abstract

The present application relates to a kind of liquid-phase discharge plasma cathode liquid and anode liquid preparation active water method applied to the technical field of plasma activated water preparation.The method is injected into the water to be treated in the anode chamber and cathode chamber separated by ion exchange membrane and forms independent circulation loop, and working gas is imported;Non-contact anode and immersion cathode are set above the liquid level of anode chamber, pulse voltage is respectively applied by using double-path independent pulse power, and anode and cathode pulse voltage parameters are independently set as different values, to generate gas-phase discharge plasma in anode chamber and liquid-phase discharge plasma in cathode chamber;During discharge process, anode and cathode solutions are independently circulated and not mixed, and high oxidation anode active water and high reduction cathode active water are obtained respectively after reaction is completed.The present application realizes the differential regulation of anode and cathode discharge mode by asymmetric electrode configuration and double-path independent power supply, and can synchronously prepare two kinds of functional active water.

Description

Technical Field

[0001] This invention relates to the field of plasma-activated water preparation technology, specifically to a method and apparatus for the simultaneous fractional preparation of cathodic reducing active water and anodic oxidizing active water in the same reactor using liquid-phase discharge plasma technology, ion exchange membrane separation, asymmetric electrode configuration, and dual independent pulse power supply. Background Technology

[0002] Plasma-activated water, rich in reactive oxygen and nitrogen species, has broad application prospects in sterilization, food preservation, medical and health care, and agricultural planting. Based on the types of reactive species and the redox properties of the solution, plasma-activated water can be divided into acidic oxidizing activated water, dominated by oxidizing reactive species, and alkaline reducing activated water, dominated by reducing reactive species. These two types of activated water are complementary in their application requirements; therefore, the simultaneous preparation and separate collection of these two different types of activated water in the same device has significant practical implications.

[0003] Chinese patent application CN114409023A discloses a device and method for preparing neutral plasma-activated water based on an ion exchange membrane. The method divides the reaction chamber into an anode chamber and a cathode chamber via an ion exchange membrane. An acidic solution is generated in the anode chamber and an alkaline solution in the cathode chamber through plasma-coupled electrolysis. The two solutions are pumped out separately and mixed in a specific ratio to form a weakly alkaline solution, which is then acidified by plasma to finally obtain neutral plasma-activated water.

[0004] While this scheme utilizes ion exchange membranes to separate the anode and cathode chambers and generate solutions with different properties separately, its technical approach has a fundamental flaw: the generated acidic and alkaline solutions are ultimately mixed to prepare neutral water, failing to achieve independent collection and separate utilization of the two types of active water, thus negating the fundamental value of fractional preparation. The reason for this lies in its symmetrical immersion electrode configuration and single-power-driven operation, which prevents independent and differentiated optimization and control of the plasma discharge processes at the anode and cathode—limited efficiency in generating oxidizing species at the anodic electrode and low concentration of reducing species at the cathode, resulting in neither product meeting the quality requirements for independent use. Within this technical framework, only mixing the two solutions can produce neutral water, failing to achieve true fractional preparation.

[0005] Therefore, the existing technology lacks a method and apparatus that can simultaneously, independently and efficiently prepare highly oxidizing anolyte active water and highly reducing catholyte active water separately, and cannot simultaneously meet the dual requirements for two different types of active water. Summary of the Invention

[0006] The technical problem to be solved by the present invention in view of the above-mentioned prior art is that although the prior art uses ion exchange membranes to separate the anode and cathode chambers and generate acidic and alkaline solutions respectively, it cannot differentiate the discharge modes of the anode and cathode due to the use of symmetrical submerged electrode configuration and single power supply drive. As a result, neither product can meet the quality requirements for independent use. In the end, they can only be mixed to prepare neutral water, and it is impossible to achieve the separate preparation and independent use of oxidizing active water and reducing active water.

[0007] To address the above problems, this invention provides a method for preparing activated water by separating the catholyte and anolyte in a liquid-phase discharge plasma, comprising the following steps:

[0008] S1: Provide a dual-chamber reactor, the interior of which is divided into an independent anode chamber and a cathode chamber by an ion exchange membrane;

[0009] S2: Inject the water to be treated into the anode chamber and the cathode chamber respectively, and make the water to be treated in the anode chamber and the cathode chamber form independent circulation loops that are not connected to each other;

[0010] S3: Introduce working gas into the anode chamber and cathode chamber respectively;

[0011] S4: A non-contact anode and an immersed cathode are set above the liquid surface in the anode chamber. Pulse voltages are applied to the anode chamber and cathode chamber respectively through dual independent pulse power supplies. The pulse voltage parameters of the anode chamber and the cathode chamber are independently set to different values ​​to optimize the yield of oxidizing active species in the gas phase discharge plasma above the liquid surface in the anode chamber and the yield of reducing active species in the liquid phase discharge plasma inside the liquid in the cathode chamber.

[0012] S5: During the discharge process, the solutions in the anode chamber and the cathode chamber circulate continuously through their respective independent circulation loops, and the solutions in the anode chamber and the cathode chamber remain unmixed throughout the discharge process.

[0013] S6: After the reaction is complete, highly oxidizing anolyte active water is obtained from the anode chamber, and highly reducing catholyte active water is obtained from the cathode chamber.

[0014] The above technical solution is the core foundation of this invention. Through an asymmetric electrode configuration of "non-contact anode gas-phase discharge + immersion cathode liquid-phase discharge," combined with dual independent pulse power supplies, the discharge parameters of the anode and cathode are independently set to different values, achieving complete decoupling of the anode and cathode discharge modes. Non-contact anode gas-phase discharge facilitates the efficient generation of short-lived, highly oxidizing active species such as ·OH and O3 at the gas-liquid interface, allowing them to directly dissolve in the solution, while fundamentally avoiding contact corrosion between the anode and the solution. Immersion cathode liquid-phase discharge facilitates the direct generation and stable accumulation of long-lived reducing active species such as H2O2 and hydrated electrons in the bulk solution phase. The ion exchange membrane allows specific ions to pass through to maintain circuit charge balance while effectively preventing macroscopic mixing of active species and the solution. The independent circulation loop accelerates mass transfer of active species from the electrode region to the bulk solution phase, increasing the final product concentration, while ensuring that the two products do not interfere with each other throughout the preparation process, ultimately achieving the simultaneous fractional preparation of highly oxidizing anode active water and highly reducing cathode active water.

[0015] As a further improvement of the present invention, the non-contact anode is a tungsten needle electrode with a tip curvature radius of 50–100 μm and a distance of 2–5 mm between the tip and the liquid surface; the immersion cathode is a stainless steel plate electrode, completely immersed in the solution within the cathode chamber; the output voltage of the dual-channel independent pulse power supply is independently adjustable within a range of 0–30 kV, the pulse frequency is independently adjustable within a range of 1–100 kHz, and the duty cycle is independently adjustable within a range of 1%–50%. The above parameter ranges are preferred ranges verified by experiments. Within these ranges, the anode gas gap can stably break down to generate gas-phase discharge plasma, and the cathode liquid-phase discharge can efficiently generate reducing active species.

[0016] As a further improvement of the present invention, an online monitoring and control step is also included: the oxidation-reduction potential (ORP) of the solutions in the anode and cathode chambers is monitored in real time. When the ORP value of the anode chamber solution reaches +700mV to +1100mV and the ORP value of the cathode chamber solution reaches -300mV to -600mV, the discharge is stopped and the highly oxidizing anode active water and highly reducing cathode active water are collected respectively. ORP is a macroscopic indicator that comprehensively reflects the quality of active water. By simultaneously judging the dual thresholds of the anode and cathode, it replaces the fixed discharge time and can ensure the consistency and reproducibility of the quality of each batch of products.

[0017] As a further improvement of this invention, when the ORP value of the solution in the anode chamber exceeds +1100mV, water to be treated is added to the anode chamber for dilution; when the ORP value of the solution in the cathode chamber is below -600mV, water to be treated is added to the cathode chamber for dilution. This over-dilution feedback mechanism further improves the ORP control logic, prevents excessive reaction from leading to overly extreme products, and achieves precise quantitative control of the quality of activated water.

[0018] As a further improvement of the present invention, by adjusting the duty cycle of the dual independent pulse power supply and / or the circulation parameters of the independent circulation loop, the composition of active species in highly oxidizing anolyte active water and / or highly reducing catholyte active water can be directionally controlled to obtain highly reducing catholyte active water with a hydrogen peroxide concentration ≥50 mg / L and / or a steady-state concentration of hydroxyl radicals ≥1.0 × 10⁻⁶. -12 High-oxidizing anolyte activated water with a concentration of mol / L. Increasing the anolyte power supply duty cycle increases the injected energy, thereby increasing the generation of ·OH; accelerating the circulation flow rate shortens the residence time of active species in the discharge region, adjusting the ratio of short-lived to long-lived active species in the product. These quantitative indicators make the quality of activated water measurable and reproducible, meeting the differentiated requirements of activated water quality for different application scenarios.

[0019] As a further improvement of the present invention, in step S2, an active particle stabilizer with a mass concentration of 0.1% to 1% is added to the water to be treated in the anode chamber, and / or a quenching inhibitor sacrificial agent with a mass concentration of 0.01% to 0.5% is added to the water to be treated in the cathode chamber. The active particle stabilizer is selected from at least one of ethanol, glycerol, or citric acid, and is used to stabilize oxidizing active species and inhibit the decomposition of hydrogen peroxide through a hydrogen bond network. The quenching inhibitor sacrificial agent is selected from at least one of ascorbic acid, sodium sulfite, or sodium thiosulfate, and is used to preferentially react with oxidizing species that diffuse from the anode region into the cathode region. The anode stabilizer forms reversible hydrogen bond associations with oxidizing active species such as ·OH through a hydrogen bond network, playing a stabilizing role rather than a traditional scavenging role. The cathode sacrificial agent preferentially removes oxidizing species that diffuse in trace amounts from the anode region into the cathode region through the ion exchange membrane, protecting the reducing active species of the cathode from oxidative interference. The two additives are added to different electrode chambers in the same method to serve complementary technical purposes, forming a functional synergy, which significantly improves the storage stability of the activated water and the purity of the product.

[0020] As a further improvement of the present invention, the method is a continuous production method, including the following steps: when the anolyte active water and the catholyte active water reach preset indicators, the continuous inlet and outlet water system is turned on, and the inlet water flow rate is controlled at 10-1000 mL / min, so that the water to be treated continuously enters the anode chamber and the cathode chamber, while the anolyte active water and the catholyte active water continuously flow out from the outlets of the anode chamber and the cathode chamber, respectively; during the continuous production process, the oxidation-reduction potential (ORP) of the solution in the anode chamber and the cathode chamber is monitored in real time, and the discharge parameters of the dual independent pulse power supply and / or the inlet water flow rate are controlled based on the monitoring results to maintain the quality stability of the produced anolyte active water and catholyte active water. This scheme elevates the present invention from intermittent laboratory operation to an industrially scalable continuous production level, and the dynamic feedback control of ORP ensures the stability of product quality under long-term operation.

[0021] The present invention also provides a liquid-phase discharge plasma fractionation device for preparing activated water to implement any of the above methods, comprising:

[0022] The main body of the dual-chamber reactor is internally divided into an independent anode chamber and a cathode chamber by an ion exchange membrane;

[0023] The independent circulation system includes a first circulation loop and a second circulation loop that are respectively connected to the anode chamber and the cathode chamber, for independently circulating the solutions in the anode chamber and the cathode chamber. In batch processing mode, it is a closed loop circulation, and in continuous production mode, it is a continuous inlet and outlet flow path.

[0024] The non-contact anode is positioned above the anode chamber, with its tip 2–5 mm above the liquid surface inside the anode chamber.

[0025] An immersion cathode is located at the bottom of the cathode chamber and is completely immersed in the solution inside the cathode chamber.

[0026] The dual-channel independent pulse power supply has two output terminals that are electrically connected to the non-contact anode and the immersion cathode, respectively, for independently controlling the discharge parameters of the anode chamber and the cathode chamber.

[0027] The working gas distribution system is connected to the gas inlets of the anode chamber and the cathode chamber respectively;

[0028] A continuous water inlet and outlet system is connected to the inlet and outlet of the anode chamber and cathode chamber, respectively;

[0029] The online monitoring and control system includes a pH sensor and an ORP sensor respectively installed in the anode chamber and cathode chamber, and a controller electrically connected to the pH sensor, the ORP sensor, a dual independent pulse power supply, a working gas distribution system, and a continuous inlet and outlet water system.

[0030] This device forms a complete correspondence with the above-mentioned method, providing a compact, highly automated hardware platform suitable for industrial application for the fractional preparation of activated water.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. By using an asymmetric electrode configuration and dual independent pulse power supplies, strong oxidizing anolyte active water with ORP > +800mV and strong reducing catholyte active water with ORP < -500mV can be obtained simultaneously in the same device, which solves the defect in the prior art that the anode and cathode liquids need to be mixed to prepare neutral water and cannot be used independently.

[0033] 2. Non-contact anode gas phase discharge efficiently utilizes the gas-liquid interface to generate short-lived strong oxidizing species that directly dissolve into the solution, while immersion cathode liquid phase discharge allows long-lived reducing species to accumulate stably in the bulk solution. Compared to the symmetrical immersion configuration, the concentrations of both oxidizing and reducing species are significantly improved.

[0034] 3. The dual-path independent pulse power supply achieves decoupling of the anode and cathode processes. The anode is matched with the high voltage required for air gap breakdown, and the cathode is matched with the optimized frequency and duty cycle required for the generation of reducing species. The anode and cathode operate under their respective optimal conditions, and the overall energy efficiency is higher than that of a single power supply solution.

[0035] 4. By using the ORP dual-threshold synchronous compliance judgment and over-dilution feedback mechanism, the high consistency of product quality between batches is ensured, and the standardized preparation of activated water is realized.

[0036] 5. The non-contact anode design completely avoids direct contact between the anode and the solution and plasma, eliminating electrode corrosion problems at the source and significantly extending equipment maintenance cycles and service life.

[0037] 6. By adjusting the duty cycle and / or circulation parameters, the concentrations of specific active species such as H2O2 and ·OH in the product can be directionally controlled to specific quantitative indicators (H2O2 ≥ 50 mg / L, ·OH steady-state concentration ≥ 1.0 × 10⁻⁶). -12 (mol / L) to meet the differentiated needs of different application scenarios.

[0038] 7. Differentiated addition of stabilizers and sacrificial agents in different compartments: The anode stabilizer stabilizes oxidizing active species by forming reversible hydrogen bond associations through a hydrogen bond network, unlike traditional free radical scavengers which extend lifespan without sacrificing activity; the cathode sacrificial agent specifically removes trace amounts of oxidizing species that ion exchange membranes cannot completely block, solving the industry-wide problem of decreased purity of cathode activated water due to transmembrane diffusion. These two additives synergistically extend the lifespan of active species, improve the purity of cathode activated water, and significantly enhance the storage stability of activated water.

[0039] 8. The continuous water inlet and outlet system, combined with ORP dynamic feedback control, can achieve stable and continuous operation for a long time, meeting the needs of industrial-scale applications. Attached Figure Description

[0040] Figure 1 This is a flowchart of the method of the present invention;

[0041] Figure 2 A bar chart comparing the ORP values ​​of the anodic and cathodic active water of Example 1 and Comparative Example 1;

[0042] Figure 3 The curves showing the change of ORP values ​​of anodic and cathodic activated water over time in a continuous operation experiment;

[0043] Figure 4 The curves show the storage stability of the active species in Examples 1 and 3. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Testing methods and standards

[0046] In the following examples and comparative examples, the activated water was characterized using the following detection methods:

[0047] pH value: Measured using a pH meter after three-point calibration.

[0048] Oxidation-reduction potential (ORP): Measured using an ORP composite electrode calibrated with an ORP standard solution.

[0049] Hydrogen peroxide concentration: The titanium sulfate spectrophotometric method was used. Take 1 mL of active water sample, add 1 mL of titanium sulfate colorimetric solution (containing 0.1 mol / L Ti(SO4)2 and 1 mol / L H2SO4), shake well, and measure the absorbance at 410 nm. Prepare a standard curve using a known concentration of H2O2 standard solution, and calculate the H2O2 concentration in the sample based on the standard curve.

[0050] Steady-state concentration of hydroxyl radicals: Terephthalic acid (TA) fluorescent probe method was used. 2.0 mL of active water sample was accurately measured into a quartz cuvette, and 0.2 mL of 20 mmol / L sodium terephthalate stock solution (prepared with 0.1 mmol / L NaOH solution, final TA concentration in the sample was 2 mmol / L) was added. The mixture was immediately vortexed for 5 seconds and incubated at room temperature (25±1℃) in the dark for 20 minutes. Subsequently, fluorescence intensity F was measured using a fluorescence spectrometer at an excitation wavelength of 315 nm and an emission wavelength of 425 nm. Each sample was measured in triplicate. Different concentrations of 2-hydroxyterephthalic acid standard solutions were treated using the same method to construct a standard curve of fluorescence intensity F versus concentration C (linear range: 0–5 × 10⁻⁶). -12 mol / L, R 2>0.99). The steady-state concentration of hydroxyl radicals in the sample was calculated by substituting the measured fluorescence intensity F into the standard curve equation, and the unit is mol / L. This method utilizes the specific reaction of terephthalic acid with hydroxyl radicals to generate 2-hydroxyterephthalic acid with fluorescent properties. It is widely used and recognized in the field of plasma-activated water research, and has high sensitivity and selectivity.

[0051] Escherichia coli kill rate: The test was conducted according to GB 15979-2024 "Hygienic Requirements for Disposable Sanitary Products". A suspension of Escherichia coli (ATCC 25922) in the logarithmic growth phase was mixed with activated water at a volume ratio of 1:9. After reacting for 30 seconds, a neutralizing agent was immediately added to terminate the reaction. The mixture was then diluted, spread onto nutrient agar plates, and incubated at 37°C for 24 hours before counting. Sterile physiological saline was used as a blank control instead of activated water, and the kill rate was calculated.

[0052] DPPH radical scavenging rate: Take 2 mL of activated water sample, add 2 mL of 0.2 mmol / L DPPH ethanol solution, shake well, and react at room temperature in the dark for 30 min. Measure the absorbance at 517 nm. Use deionized water instead of activated water as a blank control to calculate the DPPH radical scavenging rate.

[0053] Example 1: Basic Scheme of the Invention

[0054] This embodiment demonstrates the basic technical solution of the present invention.

[0055] Device setup:

[0056] The dual-chamber reactor is made of plexiglass with an internal volume of 600 mL. It is divided into two independent chambers, an anode chamber and a cathode chamber, each with a volume of 300 mL, by a cation exchange membrane (DuPont Nafion-117 perfluorosulfonic acid membrane). The anode uses a 1 mm diameter tungsten needle electrode, electrochemically etched to achieve a tip curvature radius of approximately 80 μm (measured to fall within the preferred range of 50–100 μm). The tip of the tungsten needle is precisely adjusted to 3 mm from the liquid surface in the anode chamber using a precision lifting platform. The cathode uses a 316L stainless steel plate electrode (50 mm × 30 mm × 1 mm), completely immersed in the solution in the cathode chamber. Each chamber has an independent circulation loop, driven by a peristaltic pump. The two outputs of the dual independent pulse power supply are connected to the non-contact anode and the immersed cathode, respectively. The working gas distribution system consists of an air compressor, a nitrogen cylinder, a mass flow controller (MFC), and piping, which introduces gas into the space above the liquid surface in both the anode and cathode chambers. The process flow is attached. Figure 1 As shown.

[0057] Operating steps:

[0058] 300 mL of tap water (initial conductivity 150 μS / cm, no additional electrolyte added) was injected into each chamber. Air was introduced into the anode chamber (flow rate 1.0 L / min), and nitrogen was introduced into the cathode chamber (flow rate 0.5 L / min). Dual independent pulse power supplies were used to output: anode – peak voltage 15 kV, frequency 10 kHz, duty cycle 20%; cathode – peak voltage 8 kV, frequency 5 kHz, duty cycle 30%. Independent circulation was initiated, with the circulation flow rate in both chambers set to 200 mL / min. Discharge was performed continuously for 10 min, ensuring the solutions in both chambers remained separate during the discharge. After discharge, the activated water was collected from both the anode and cathode chambers.

[0059] Test results:

[0060] Anodic activated water: pH 3.2, ORP +850mV, steady-state concentration of hydroxyl radicals (·OH) 1.5×10⁻⁶ -12 mol / L, E. coli kill rate of 99.99% in 30s. Cathode activated water: pH 10.5, ORP -580mV, H2O2 concentration 65mg / L, DPPH free radical scavenging rate 85%.

[0061] In other embodiments of the present invention, the water to be treated can also be deionized water, surface water, or an electrolyte solution containing at least one of Na₂SO₄, NaCl, and KNO₃, and the above-mentioned effects can be achieved with a conductivity in the range of 50–500 μS / cm. The working gas can also be selected from any one or more mixed gases of oxygen and argon; the types of working gases introduced into the anode chamber and the cathode chamber can be the same or different, and the above-mentioned effects can be achieved by independently controlling the gas flow rate in the range of 0.1–2.0 L / min.

[0062] In other verification experiments of this invention, stable anodic gas-phase discharge could be achieved when the radius of curvature of the tungsten needle tip was within the range of 50–100 μm and the distance between the tip and the liquid surface was within the range of 2–5 mm. When the radius of curvature of the tungsten needle tip was 50 μm and the distance between the tip and the liquid surface was 2 mm, the anodic discharge was stable, and the ORP of the anodic active water reached +880 mV; when the radius of curvature of the tip was 100 μm and the distance between the tip and the liquid surface was 5 mm, the anodic discharge was stable, and the ORP of the anodic active water reached +820 mV. When the peak voltage of the anode was within the range of 10–20 kV, the frequency was within the range of 5–15 kHz, and the duty cycle was within the range of 10%–30%, and the peak voltage of the cathode was within the range of 5–12 kV, the frequency was within the range of 3–10 kHz, and the duty cycle was within the range of 20%–40%, the effective preparation of anode and cathode active water could be achieved. The anode pulse voltage parameters and the cathode pulse voltage parameters were independently set to different values ​​to optimize the yield of oxidizing active species and the yield of reducing active species, respectively.

[0063] In the verification experiment of this invention, when the anode duty cycle was increased from 20% to 30%, the steady-state concentration of hydroxyl radicals in the anode active water increased from 1.5 × 10⁻⁶ to 1.5 × 10⁻⁶. -12 The concentration was increased to 2.2 × 10 mol / L. -12 The concentration of hydrogen peroxide in the cathode activated water increased from 65 mg / L to 85 mg / L when the cathode circulation flow rate was reduced from 200 mL / min to 100 mL / min. This indicates that the composition of active species can be effectively directionally controlled by adjusting the duty cycle and / or circulation parameters.

[0064] Results analysis:

[0065] This embodiment utilizes an asymmetric configuration of non-contact anodic gas-phase discharge and immersion cathode liquid-phase discharge, coupled with dual independent pulse power supplies to independently set different values ​​for the anode and cathode parameters, successfully obtaining highly oxidizing anodic active water and highly reducing cathode active water simultaneously in the same device. The anode employs a higher peak voltage to break down the gas gap and generate gas-phase discharge, efficiently producing oxidizing species such as ·OH at the gas-liquid interface; the cathode employs a lower peak voltage and an optimized frequency duty cycle to promote liquid-phase discharge and generate reducing species such as H2O2. Independent circulation loops ensure that the two products do not interfere with each other, and the ion exchange membrane effectively prevents macroscopic mixing of the solutions in the two chambers.

[0066] Comparative Example 1

[0067] This comparative example uses a symmetrical immersion electrode + single power supply scheme, and the other conditions are kept the same as in Example 1 for intuitive comparison.

[0068] Device Modification: Remove the non-contact tungsten needle anode and replace it with the same 316L stainless steel plate electrode as the cathode, completely immersed in the solution in the anode chamber. Remove the dual independent pulse power supply and replace it with a single pulse power supply (parameters taken as the midpoint between the two: peak voltage 10kV, frequency 10kHz, duty cycle 20%), simultaneously supplying power to both the anode and cathode.

[0069] Operating steps: Same as in Example 1.

[0070] Test results:

[0071] Anodic activated water: pH 3.8, ORP +720mV, steady-state concentration of hydroxyl radicals 0.8×10⁻⁶ -12 mol / L, E. coli kill rate of 99.9% in 30s. Cathode activated water: pH 9.2, ORP -350mV, H2O2 concentration 25mg / L, DPPH free radical scavenging rate 55%.

[0072] Comparative analysis of results:

[0073] Compare the data from Example 1 with those from Comparative Example 1, see [link to relevant documentation]. Figure 2 The ORP value of the anolyte active water in Example 1 was 130 mV higher than that in Comparative Example 1, and the absolute value of the ORP value of the cathode active water was 230 mV higher than that in Comparative Example 1. The H2O2 concentration of the cathode water in Example 1 was 2.6 times that in Comparative Example 1, and the hydroxyl radical concentration of the anolyte water was 1.9 times that in Comparative Example 1. The sterilization rate of the anolyte water in Example 1 (99.99%) was significantly better than that in Comparative Example 1 (99.9%), and the antioxidant capacity of the cathode water (85%) was significantly better than that in Comparative Example 1 (55%).

[0074] This comparative example fully demonstrates that, under the same energy consumption conditions, the asymmetric electrode configuration + dual independent pulse power supply scheme of this invention significantly outperforms the symmetric immersion + single power supply scheme in terms of both anode and cathode active water quality. This is because, in the symmetric configuration, the anode and cathode discharge modes are identical, and a single power supply cannot provide optimal discharge parameters for each separately—anode gas gap breakdown requires a higher voltage, and cathode liquid phase discharge requires optimized frequency and duty cycle; a single power supply uses intermediate values, resulting in neither operating under optimal conditions. In contrast, this invention achieves complete decoupling and separate optimization of the anode and cathode discharge modes through the asymmetric configuration and dual independent power supply, thus achieving unexpected technical results.

[0075] Comparative Example 2: Anode Discharge Only Scheme

[0076] This comparative example is used to verify the necessity of independent cathode discharge.

[0077] Device modification: The non-contact tungsten needle anode and its power supply parameters are retained (same as in Example 1), and the cathode is replaced with a grounded stainless steel plate (without applying an independent discharge voltage). All other conditions are the same as in Example 1.

[0078] Test results:

[0079] Cathode activated water: pH 8.5, ORP -150mV, H2O2 concentration 8mg / L, DPPH free radical scavenging rate 30%.

[0080] Comparative analysis of results:

[0081] Compared to Example 1, the quality of the cathode active water in Comparative Example 2 was significantly reduced: the ORP (absolute value) decreased by 430 mV, the H2O2 concentration was only about 1 / 8 of that in Example 1, and the antioxidant capacity was only about 1 / 3 of that in Example 1. This comparative example demonstrates that the trace amounts of reducing species in the solution during anodic discharge are far from sufficient to obtain high-quality reducing active water; independent liquid-phase discharge at the cathode is a necessary condition for the generation of highly reducing cathode active water.

[0082] Example 2: ORP Feedback Control Scheme

[0083] This embodiment demonstrates the ORP online monitoring and feedback control scheme of the present invention.

[0084] Based on the device in Example 1, an online ORP sensor is added to both the anode chamber and the cathode chamber. The sensor probes are immersed in their respective circulation loops, and the signals are transmitted to the controller in real time.

[0085] The anode ORP threshold was set to +800mV, and the cathode ORP threshold was set to -500mV. The ORP values ​​of both chambers were monitored in real time during discharge. When the anode ORP value reached +800mV and the cathode ORP value reached -500mV (in this experiment, the ORP values ​​of both chambers reached the target simultaneously after 8 minutes of discharge), the discharge was automatically stopped and the product was collected. If the anode ORP value exceeded +1100mV during discharge, the controller automatically added 50mL of raw water to the anode chamber for dilution; if the cathode ORP value was below -600mV, it automatically added 50mL of raw water to the cathode chamber for dilution. Other operating conditions were the same as in Example 1.

[0086] In other embodiments of the present invention, the anode ORP threshold can be selected in the range of +700mV to +1100mV, and the cathode ORP threshold can be selected in the range of -300mV to -600mV. The specific threshold setting can be adjusted according to the specific requirements of the target application scenario for the quality of activated water.

[0087] result:

[0088] In 10 consecutive batches of repeated experiments, the standard deviation of the ORP value of the anolyte active water was ±15mV, and the standard deviation of the ORP value of the cathode active water was ±20mV. Compared with the fixed discharge time used in Example 1, this example effectively eliminated batch-to-batch differences caused by factors such as ambient temperature and water quality fluctuations by using simultaneous ORP dual threshold judgment, and the product quality consistency was significantly improved. The over-dilution mechanism was triggered once in 10 batches (the anolyte ORP of the 5th batch reached +1120mV, triggering over-dilution. The system automatically added 50mL of raw water to the anode chamber. After dilution, the ORP dropped back to +1050mV, which was within the preset threshold range. Then, the discharge continued until the ORP reached the target value of +800mV again, after which the discharge stopped and the product was collected), effectively preventing over-reaction of the product.

[0089] Example 3: Additive Enhancement Scheme

[0090] This embodiment illustrates the additive enhancement scheme of the present invention.

[0091] Based on Example 1, 0.5% (mass concentration) ethanol was added to the anolyte as an active particle stabilizer, and 0.05% (mass concentration) as ascorbic acid was added to the catholyte as a quenching inhibition sacrificial agent. All other operating conditions were the same as in Example 1.

[0092] Three additional control experiments were set up: Group A - only ethanol was added to the anolyte, and no sacrificial agent was added to the catholyte; Group B - no stabilizer was added to the anolyte, and only ascorbic acid was added to the catholyte; Group C - no additives were added to either the anode or cathode (same as in Example 1).

[0093] To test the storage stability of active species, each group of activated water was stored in a constant temperature environment of 25℃, and samples were taken at 0h, 24h, 72h, and 168h to test the steady-state concentration of hydroxyl radicals in the anolyte and the concentration of H2O2 in the cathode.

[0094] result:

[0095] In this embodiment (with simultaneous addition of both agents): the concentration retention rate of anolyte water·OH after 168 hours was 58% of the initial value (compared to only 15% in Group C of Example 1), and the half-life was extended from approximately 2 hours to approximately 6 hours; the concentration retention rate of cathode water H2O2 after 168 hours was 75% (compared to only 40% in Group C of Example 1). Group A (anolyte stabilizer only): the half-life extension effect of anolyte water·OH was similar to that in this embodiment, but the retention rate of cathode water H2O2 was comparable to that of Group C. The results of Group A indicate that trace amounts of oxidizing species diffuse into the cathode chamber through the ion exchange membrane in the anode chamber, consuming the reducing species in the cathode. Group B (cathode sacrificial agent only): the retention rate of cathode water H2O2 increased to approximately 60%, but the stability of anolyte water·OH was comparable to that of Group C. The results of Group B further confirm the existence of transmembrane diffusion, and the addition of the cathode sacrificial agent effectively inhibited this consumption.

[0096] For the results analysis, please refer to [link / details]. Figure 4 This embodiment demonstrates that the anolyte stabilizer forms reversible hydrogen bonds with ·OH through a hydrogen bond network, effectively inhibiting the free diffusion and self-quenching of ·OH and extending the lifetime of oxidizing active species; the cathode sacrificial agent preferentially removes oxidizing species that diffuse in trace amounts from the anolyte region into the cathode region through the ion exchange membrane, protecting reducing active species such as H2O2 from oxidative interference. The two additives are added separately and differentiatedly, each serving an independent technical purpose, while their simultaneous addition synergistically ensures the quality and stability of both products.

[0097] Example 4: Continuous Production Solution

[0098] This embodiment demonstrates the continuous production scheme of the present invention.

[0099] Based on the device in Example 1, a continuous water inlet and outlet system is added, including two independent inlet peristaltic pumps and two independent outlet overflow ports, which are respectively connected to the anode chamber and the cathode chamber.

[0100] After discharge begins, the ORP values ​​of the solutions in both chambers are monitored in real time. When the ORP of both chambers reaches the preset target (anodic ORP > +800mV and cathode ORP < -500mV, approximately 8 minutes after discharge), the continuous influent / outfluent mode is activated: the influent flow rate is set to 100mL / min, with 300mL for each chamber (anode and cathode), corresponding to a theoretical hydraulic residence time of 3 minutes. After continuous flow is activated, discharge parameters are adjusted through dynamic ORP feedback control to compensate for the impact of shortened residence time on the accumulation of active species, thereby ensuring product quality similar to that of batch treatment. Anode active water and cathode active water flow continuously from their respective outlets and are collected.

[0101] During operation, the online monitoring and control system receives real-time monitoring data from the ORP and pH sensors. Based on the preset ORP target range (anode ORP +800mV~+1100mV, cathode ORP -600mV~-300mV), the controller automatically adjusts the discharge parameters of the dual independent pulse power supply and / or the influent flow rate: when the anode ORP deviates from the upper limit of the target range, the anode power supply duty cycle is appropriately reduced or the influent flow rate is increased; when the cathode ORP deviates from the lower limit of the target range, the cathode power supply duty cycle is appropriately increased or the influent flow rate is decreased.

[0102] The system ran continuously for 24 hours, with samples taken and tested every 2 hours. Results are shown below. Figure 3 :

[0103] The ORP value of the anolyte active water was maintained between +820mV and +870mV, and the pH value was maintained between 2.8 and 3.5; the ORP value of the catholyte active water was maintained between -550mV and -590mV, and the pH value was maintained between 10.0 and 11.2. Through closed-loop feedback control, the ORP values ​​of both the anode and cathode active water remained within the preset quality range for 24 hours of continuous operation. After 24 hours of continuous operation, the tip of the tungsten needle at the anode was inspected and no corrosion was found; the conductivity of the ion exchange membrane was measured and showed no significant change compared to before operation. The results indicate that the asymmetric electrode configuration and dynamic feedback control scheme of this invention can meet the stability requirements of long-term continuous production, the non-contact anode design avoids electrode corrosion at its source, and the ion exchange membrane exhibits good chemical stability in the plasma environment.

[0104] In other embodiments of the present invention, continuous and stable production can be achieved with an influent flow rate in the range of 10 to 1000 mL / min. The hydraulic retention time can be flexibly controlled by adjusting the influent flow rate to meet the needs of different treatment scales.

[0105] Results Summary Discussion

[0106] The results of Comparative Example 1 demonstrate that simply using an ion-exchange membrane to separate the anode and cathode chambers, without altering the core structure of the symmetrical submerged electrode and single power supply, cannot achieve high-quality fractional preparation. This invention fundamentally solves this problem through systematic innovations such as asymmetric electrode configuration, dual independent pulse power supplies, and independent circulation loops. Specifically:

[0107] First, by employing an asymmetric electrode configuration of non-contact anode gas-phase discharge and immersion cathode liquid-phase discharge, complete decoupling of the anode and cathode discharge modes is achieved within the same device. Comparative data from Example 1 and Comparative Example 1 directly demonstrate that this asymmetric configuration significantly outperforms the symmetric immersion configuration in both anode water oxidation and cathode water reduction. Within the aforementioned preferred parameter range of this invention, the fractional preparation of high-quality activated water can be stably achieved.

[0108] Secondly, the dual-path independent pulse power supply sets the discharge parameters of the anode and cathode to different values, so that the anode matches the high voltage required for air gap breakdown, and the cathode matches the optimized frequency and duty cycle required for the generation of reducing species. Both operate under their respective optimal conditions, which is a technical effect that a single power supply solution cannot achieve.

[0109] Third, the simultaneous ORP threshold judgment and over-dilution feedback mechanism (Example 2) realizes online precise control of activated water quality, and the inter-batch ORP fluctuation is controlled within ±20mV, which solves the problem of large inter-batch differences in the traditional fixed-time discharge scheme.

[0110] Fourth, the compartmentalized addition of stabilizers and sacrificial agents (Example 3) provides an alternative means to further improve the stability and purity of activated water, extending the ·OH half-life by about 3 times and increasing the H2O2 storage retention rate by about 35 percentage points.

[0111] Fifth, the continuous production scheme (Example 4) verifies that the present invention has the potential for industrial application with long-term stable continuous operation, and the ORP fluctuation is less than ±30mV during 24-hour continuous operation.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing activated water by separating cathodic and anodic solutions in liquid-phase discharge plasma, characterized in that, Includes the following steps: S1: A dual-chamber reactor is provided, wherein the interior of the dual-chamber reactor is divided into an independent anode chamber and a cathode chamber by an ion exchange membrane; S2: Inject the water to be treated into the anode chamber and the cathode chamber respectively, and make the water to be treated in the anode chamber and the cathode chamber form independent circulation loops that are not interconnected; S3: Introduce working gas into the anode chamber and the cathode chamber respectively; S4: A non-contact anode and an immersed cathode are arranged above the liquid surface in the anode chamber. Pulse voltages are applied to the anode chamber and the cathode chamber respectively through dual independent pulse power supplies. The pulse voltage parameters of the anode chamber and the cathode chamber are independently set to different values ​​to optimize the yield of oxidizing active species in the gas phase discharge plasma above the liquid surface in the anode chamber and the yield of reducing active species in the liquid phase discharge plasma inside the liquid in the cathode chamber, respectively. S5: During the discharge process, the solution in the anode chamber and the solution in the cathode chamber circulate continuously through their respective independent circulation loops, and the solution in the anode chamber and the solution in the cathode chamber remain unmixed throughout the discharge process; S6: After the reaction is completed, highly oxidizing anolyte active water is obtained from the anode chamber, and highly reducing catholyte active water is obtained from the cathode chamber.

2. The method for preparing activated water by separating liquid-phase discharge plasma cathode liquid and anolyte according to claim 1, characterized in that, The non-contact anode is a tungsten needle electrode with a tip curvature radius of 50–100 μm and a distance of 2–5 mm between the tip and the liquid surface; the immersion cathode is a stainless steel plate electrode, which is completely immersed in the solution in the cathode chamber; the output voltage of the dual-channel independent pulse power supply is independently adjustable from 0 to 30 kV, the pulse frequency is independently adjustable from 1 to 100 kHz, and the duty cycle is independently adjustable from 1% to 50%.

3. The method for preparing activated water by separating liquid-phase discharge plasma cathode liquid and anolyte according to claim 1, characterized in that, It also includes online monitoring and control steps: real-time monitoring of the oxidation-reduction potential (ORP) of the solutions in the anode chamber and the cathode chamber respectively; when the ORP value of the solution in the anode chamber reaches +700mV to +1100mV and the ORP value of the solution in the cathode chamber reaches -300mV to -600mV, the discharge is stopped and the highly oxidizing anode active water and the highly reducing cathode active water are collected respectively.

4. The method for preparing activated water by separating the cathodic liquid and anodic liquid in liquid-phase discharge plasma according to claim 3, characterized in that, When the ORP value of the solution in the anode chamber exceeds +1100mV, water to be treated is added to the anode chamber for dilution; when the ORP value of the solution in the cathode chamber is below -600mV, water to be treated is added to the cathode chamber for dilution.

5. The method for preparing activated water by separating liquid-phase discharge plasma cathode liquid and anolyte according to claim 1, characterized in that, By adjusting the duty cycle of the dual independent pulse power supply and / or the circulation parameters of the independent circulation loop, the composition of active species in the highly oxidizing anolyte and / or highly reducing catholyte is directionally controlled to obtain highly reducing catholyte with a hydrogen peroxide concentration ≥50 mg / L and / or a steady-state concentration of hydroxyl radicals ≥1.0 × 10⁻⁶. -12 The highly oxidizing anolyte active water at a concentration of mol / L.

6. The method according to claim 1, characterized in that, In step S2, an active particle stabilizer with a mass concentration of 0.1% to 1% is added to the water to be treated in the anode chamber, and / or a quenching inhibitor sacrificial agent with a mass concentration of 0.01% to 0.5% is added to the water to be treated in the cathode chamber. The active particle stabilizer is selected from at least one of ethanol, glycerol or citric acid, and is used to stabilize oxidative active species and inhibit the decomposition of hydrogen peroxide through a hydrogen bond network. The quenching inhibition sacrificial agent is selected from at least one of ascorbic acid, sodium sulfite, or sodium thiosulfate, and is used to preferentially react with oxidizing species that diffuse from the anodic region into the cathode region.

7. The method according to claim 1, characterized in that, The method is a continuous production method, including the following steps: Once the anolyte active water and the cathode active water reach the preset targets, the continuous water inlet and outlet system is turned on, and the inlet flow rate is controlled at 10-1000 mL / min, so that the water to be treated continuously enters the anode chamber and the cathode chamber, while the anolyte active water and the cathode active water continuously flow out from the outlets of the anode chamber and the cathode chamber, respectively. During continuous production, the oxidation-reduction potential (ORP) of the solutions in the anode and cathode chambers is monitored in real time, and the discharge parameters of the dual independent pulse power supply and / or the inlet water flow rate are controlled based on the monitoring results to maintain the stable quality of the produced anode active water and cathode active water.

8. A liquid-phase discharge plasma fractionation apparatus for preparing activated water according to any one of claims 1-7, characterized in that, include: The main body of the dual-chamber reactor is internally divided into an independent anode chamber and a cathode chamber by an ion exchange membrane; An independent circulation system includes a first circulation loop and a second circulation loop respectively connected to the anode chamber and the cathode chamber, for allowing the solutions in the anode chamber and the cathode chamber to circulate independently; A non-contact anode is disposed above the anode chamber, with its tip positioned 2–5 mm above the liquid surface inside the anode chamber. An immersion cathode is disposed at the bottom of the cathode chamber and is completely immersed in the solution inside the cathode chamber; A dual-channel independent pulse power supply, whose two output terminals are electrically connected to the non-contact anode and the immersion cathode respectively, is used to independently control the discharge parameters of the anode chamber and the cathode chamber. The working gas distribution system is connected to the gas inlets of the anode chamber and the cathode chamber, respectively; A continuous water inlet and outlet system is connected to the inlet and outlet of the anode chamber and the cathode chamber, respectively. The online monitoring and control system includes a pH sensor and an ORP sensor respectively installed in the anode chamber and the cathode chamber, and a controller electrically connected to the pH sensor, the ORP sensor, the dual independent pulse power supply, the working gas distribution system, and the continuous water inlet and outlet system.

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