Preparation method and system of ultrapure water for cleaning perovskite solar cell substrate

Abstract

The application discloses a kind of perovskite solar cell substrate cleaning ultra-pure water preparation method and system, belong to ultra-pure water preparation technical field.The perovskite solar cell substrate cleaning ultra-pure water preparation method adopts nine-stage preparation process of pretreatment, double-stage reverse osmosis desalination, TOC depth oxidation, precision filtration, layered metal ion special removal, halogen ion accurate processing, deep desalination polishing, double-mode degassing, pollution prevention transport, organic matter is synergistically degraded by ozone micro-bubble combined with double-wavelength ultraviolet, and the effluent TOC is controlled below 1ppb;Three-layer functional composite resin is used to remove various metal ions in layers, and ion selectivity is greatly improved;Rely on silver loaded resin dynamic regulation and control to remove halogen ions, and use nitrogen purging and vacuum degassing double mode to ensure low dissolved oxygen environment;At the same time, PLC control system and sterile anti-pollution conveying pipeline are matched, and the high-precision cleaning requirement of perovskite battery substrate can be met.

Description

Technical Field

[0001] This invention belongs to the field of ultrapure water preparation technology, specifically relating to a method and system for preparing ultrapure water for cleaning perovskite solar cell substrates. Background Technology

[0002] Perovskite solar cells, as an emerging photovoltaic technology, have attracted much attention due to their excellent photoelectric conversion efficiency and low raw material costs. In the production process of perovskite solar cells, the FTO (fluorine-doped tin oxide) conductive glass substrate needs to be ultrasonically cleaned with ultrapure water to remove surface contaminants. The purity of the ultrapure water directly affects the cleanliness of the substrate, which in turn affects the uniformity of the perovskite film and the final performance of the cell. Perovskite materials are extremely sensitive to metal ions, halide ions, organic matter, and particulate matter; even trace impurities can lead to a decrease in cell efficiency or a shortened lifespan. Therefore, the ultrapure water used for cleaning perovskite solar cell substrates must meet extremely stringent water quality standards: resistivity not less than 18.2 megohm-cm (25 degrees Celsius), TOC (total organic carbon) content not greater than 5 ppb, metal ion concentration not greater than 1 ppt, halide ion concentration not greater than 10 ppt, dissolved oxygen content not greater than 3 ppb, and particulate matter (particle size greater than or equal to 0.1 micrometers) not greater than 1 particle per milliliter.

[0003] Existing ultrapure water preparation methods typically employ a traditional process route of "pretreatment → first-stage reverse osmosis → second-stage reverse osmosis → electro-deionization → polishing resin". However, this process has the following shortcomings: First, the TOC removal depth is insufficient. Existing technologies mostly use activated carbon adsorption to remove TOC. However, the efficiency of activated carbon drops sharply after adsorption saturation, and it cannot decompose recalcitrant organic matter, resulting in large fluctuations in the TOC of the effluent.

[0004] Second, the selective removal capability of metal ions is poor. Existing technologies typically use a single nucleus-level mixed-bed resin for desalination, which lacks targeted selection for specific metal ions sensitive to perovskite solar cells, and the resin is easily saturated by non-target ions, resulting in a shortened service life.

[0005] Third, a dedicated halogen-free ion removal and monitoring unit. Current technologies rely entirely on raw water quality and random retention by the reverse osmosis membrane to determine halogen ion concentration.

[0006] Fourth, there is no degassing unit. Current technology lacks any degassing unit, resulting in an effluent dissolved oxygen content of 5 to 8 ppm, which fails to meet the perovskite process's requirement of no more than 3 ppb of dissolved oxygen.

[0007] Fifth, the pipeline is severely polluted. Existing technology uses ordinary PVDF pipelines, which have a high inner surface roughness, making them prone to biofilm growth. Furthermore, there are no circulating sterilization measures, resulting in water quality at the point of use being far lower than that at the outlet.

[0008] Therefore, there is a need for a method for preparing ultrapure water for cleaning perovskite solar cell substrates that can deeply remove TOC, specifically remove certain metal ions and halide ions, and has degassing protection and anti-contamination transport functions. Summary of the Invention

[0009] The purpose of this invention is to provide a method and system for preparing ultrapure water for cleaning perovskite solar cell substrates, so as to solve the problems of insufficient TOC removal depth, poor metal ion selectivity, lack of halogen ion removal, lack of degassing protection, and contamination of transport pipelines in the prior art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: First, the present invention provides a method for preparing ultrapure water for cleaning perovskite solar cell substrates, comprising the following steps: Step S1: The raw water is pretreated by passing it sequentially through a quartz sand filter and an activated carbon filter to remove suspended solids, colloidal particles, and large molecular organic matter. The quartz sand filter uses quartz sand of different particle sizes to remove suspended solids and colloidal particles larger than 10 micrometers. The activated carbon filter uses the adsorption properties of activated carbon to remove residual chlorine, organic matter, and odor substances from the water, thereby reducing the turbidity of the pretreated water to below 0.5 NTU and the residual chlorine to less than 0.1 mg / L. Step S2: The pretreated water is desalinated sequentially through a primary reverse osmosis unit and a secondary reverse osmosis unit. The primary reverse osmosis unit uses a low-pressure, fouling-resistant polyamide composite reverse osmosis membrane with an operating pressure of 1.0 to 1.2 MPa and a desalination rate of more than 98%. The secondary reverse osmosis unit further desalinates the water, reducing the conductivity of the secondary reverse osmosis permeate to below 5 microsiemens per centimeter. Step S3: Pass the secondary reverse osmosis permeate into the TOC deep oxidation module to first oxidize and degrade the organic matter in the water, and then use an ultrafiltration membrane to remove the oxidation products, so that the TOC concentration of the effluent is reduced to below 1 ppb. Step S4: The effluent from step S3 is passed into a precision filter, and discharged after the precision filter traps particulate matter; moreover, the precision filter has an accuracy of 5 micrometers, preferably using a pleated polypropylene filter element, to trap particulate matter that may be generated in the preceding unit, and to protect the subsequent metal ion removal and electro-deionization units. Step S5: The effluent from Step S4 is fed into a metal ion removal module. Transition metal ions, alkali metal ions, and heavy metal ions are removed sequentially through a three-layer composite resin layered filling structure. Each resin layer is filled with chelating resin with optimized functional groups for the target metal ions. The saturation status of each resin layer is monitored by an independent resin saturation sensor. When any resin layer becomes saturated, the system automatically switches to a backup tank and sends a saturation warning. Existing technologies can only replace the entire resin and do not have layered monitoring functions. This invention achieves single-layer resin saturation warning and seamless switching of the entire tank. Step S6: The effluent from Step S5 is passed into the halide ion control module, where chloride and bromide ions are removed by silver-loaded resin, and the treatment intensity is dynamically adjusted according to the halide ion concentration in the effluent. This step uses a special removal column for silver-loaded resin, which precisely removes chloride and bromide ions by precipitation reaction with the silver-loaded resin, with a removal capacity of not less than 1.0 mmol / g. Step S7: The effluent from step S6 is passed into an electro-deionization device for deep desalination. Under the action of a DC electric field, deep desalination is achieved through the synergistic effect of the ion exchange membrane and ion exchange resin, and the resistivity of the effluent is stabilized at above 18.2 megohm-cm (25 degrees Celsius). Then, it is polished by ion exchange with polishing resin, and the total metal ion concentration of the effluent is no more than 1 ppt. Step S8: The effluent from step S7 is passed into the degassing protection module for degassing treatment. The degassing protection module operates in a dual mode, with nitrogen purging as the main method and vacuum degassing as the auxiliary method. Step S9: The effluent from Step S8 is transported to the point of use via a pollution-proof delivery pipeline. This pipeline is equipped with a UV-ozone circulation sterilization system that periodically adds ozone intermittently. Each point of use is equipped with a terminal filter. The pollution-proof delivery pipeline is made of high-purity PVDF (polyvinylidene fluoride) or PFA (perfluoroalkoxy resin), and employs an automated track welding process to ensure no dead corners and no precipitation. The inner surface roughness Ra is no greater than 0.4 micrometers. The flow rate within the pollution-proof delivery pipeline is maintained at no less than 1.5 meters per second to prevent particulate matter deposition. The UV-ozone circulation sterilization system adds ozone intermittently 1 to 2 times per shift (at a concentration of 0.5 mg / L, for 30 minutes) to prevent biofilm formation. Each point of use is equipped with a 0.1-micrometer terminal filter to ensure that the final effluent contains no more than one particle per milliliter (particle size greater than or equal to 0.1 micrometers).

[0011] Furthermore, in step S3, hydroxyl radicals are generated through the synergistic effect of ozone microbubbles and dual-wavelength ultraviolet light with wavelengths of 185 nm and 254 nm to deeply oxidize and degrade organic matter in the water. The dosage of ozone microbubbles is 1 to 3 mg / L, and the average diameter of the microbubbles is no more than 50 μm. The molecular weight cutoff of the ultrafiltration membrane is 5000 to 10000 Daltons. The residence time of water in the TOC deep oxidation module is 10 to 20 minutes. The TOC concentration in the effluent is monitored in real time by an online TOC sensor, and the ozone dosage and ultraviolet lamp power are dynamically adjusted according to the TOC concentration in the effluent.

[0012] Based on this, this step employs a three-stage combined process of ozone microbubbles, dual-wavelength ultraviolet light, and ultrafiltration: (1) Ozone microbubble enhanced mass transfer: Ozone with a dosage of 1 to 3 mg / L is introduced into the water in the form of microbubbles with an average diameter of no more than 50 micrometers. The microbubbles have a large specific surface area and a slow rising speed, which significantly improves the ozone utilization rate. Ozone decomposes in water to produce hydroxyl radicals. (2) 185 nm ultraviolet light generates hydroxyl radicals: 185 nm ultraviolet light can directly photolyze water molecules to generate hydroxyl radicals. The oxidation potential of hydroxyl radicals is as high as 2.8 V, which can non-selectively oxidize and decompose most organic matter. (3) Simultaneous sterilization with 254 nm ultraviolet light: 254 nm ultraviolet light has a sterilization effect, simultaneously inactivating microorganisms in the water and preventing microbial contamination of subsequent treatment units; (4) Ultrafiltration to retain oxidation products: By using an ultrafiltration membrane with a molecular weight of 5,000 to 10,000 Daltons to retain oxidation products and biological debris, the cleanliness of the effluent is ensured.

[0013] Furthermore, the TOC removal rate is no less than 95% under the synergistic effect of the above four mechanisms, and the TOC concentration in the effluent can be stably controlled below 1 ppb.

[0014] Further, in step S5, the three-layer composite resin layered filling structure, from top to bottom, consists of: a chelating resin layer with optimized functional groups for transition metal ions, a crown ether ketone resin layer with optimized functional groups for alkali metal ions, and an aminophosphate resin layer with optimized functional groups for heavy metal ions; the chelating resin layer is filled with chelating resin containing chelating functional groups, the crown ether ketone resin layer is filled with crown ether ketone resin containing crown ether ketone functional groups, and the aminophosphate resin layer is filled with aminophosphate resin containing aminophosphate functional groups. Therefore, due to the adoption of a three-layer composite resin layered filling structure, the functional groups are optimized for the transition metals, alkali metals, and heavy metals sensitive to perovskite solar cells, respectively, resulting in a selectivity coefficient 10 to 100 times higher than that of traditional single nucleoside-level mixed-bed resins.

[0015] Further, in step S6, the control logic for dynamically adjusting the treatment intensity is as follows: when the effluent halide ion concentration is no greater than 2 ppt, switch to single-column operation mode, with only the main column operating; when the effluent halide ion concentration is greater than 2 ppt but no greater than 5 ppt, maintain the current operation mode; when the effluent halide ion concentration is greater than 5 ppt, switch to dual-column series operation mode, with the main column and the standby column operating in series; when the remaining lifespan of the main column resin is no greater than 24 hours, automatically switch to standby column operation alone and send a replacement warning. Thus, this invention, by setting a highly sensitive online halide ion sensor and an automatic single / dual-column switching valve, can dynamically adjust the treatment intensity according to the effluent halide ion concentration, balancing the treatment effect and resin lifespan.

[0016] Furthermore, when the nitrogen pressure is not less than 0.2 MPa, a nitrogen purging mode is adopted, and the nitrogen flow rate is dynamically adjusted according to the dissolved oxygen concentration. When the nitrogen pressure is less than 0.2 MPa, it automatically switches to vacuum degassing mode to reduce the dissolved oxygen content of the effluent to below 3 ppb. In nitrogen purging mode, high-purity nitrogen is introduced into the water in the form of microbubbles through a nitrogen microporous disperser. When the dissolved oxygen concentration is greater than 3 ppb, the nitrogen flow rate is increased by 1 liter per minute; when the dissolved oxygen concentration is less than 1 ppb, the nitrogen flow rate is decreased by 1 liter per minute. In vacuum degassing mode, a vacuum pump is activated to maintain a vacuum level not exceeding 50 mbar, and an abnormal nitrogen supply warning is sent. The core advantage of the dual-mode design lies in redundancy: under normal operating conditions, the high efficiency of nitrogen purging is utilized; under abnormal operating conditions, it automatically switches to vacuum degassing mode to ensure that the system does not shut down due to a single gas source failure. The dissolved oxygen content of the effluent is stably controlled below 3 ppb.

[0017] Furthermore, it also includes intelligent control steps: real-time acquisition of resistivity, TOC concentration, total metal ion concentration, total halide ion concentration, and dissolved oxygen concentration parameters through a PLC controller, and an anomaly detection of the acquired data using an isolated forest algorithm: when the anomaly score exceeds 0.8, an emergency switch is triggered and all backup modules are activated; when the anomaly score exceeds 0.6, an early warning notification is sent; at the same time, a lifespan prediction model based on historical data is used to predict the remaining lifespan of each consumable, and a replacement warning is sent when the remaining lifespan of any consumable is no more than 24 hours.

[0018] Second, this invention provides an ultrapure water preparation system for cleaning perovskite solar cell substrates, including a pretreatment unit, a reverse osmosis desalination unit, an electro-deionization device, and a polishing resin. It also includes a TOC deep oxidation module, a precision filter, a metal ion removal module, a halide ion control module, a degassing protection module, a contamination-proof delivery pipeline, and a PLC controller. The pretreatment unit includes a quartz sand filter and an activated carbon filter, with the outlet of the quartz sand filter connected to the inlet of the activated carbon filter. The reverse osmosis desalination unit includes a primary reverse osmosis device and a secondary reverse osmosis device, with the outlet of the primary reverse osmosis device connected to the inlet of the secondary reverse osmosis device. The TOC deep oxidation module includes an ozone microbubble generator, a dual-wavelength ultraviolet device, and an ultrafiltration membrane, with the outlet of the secondary reverse osmosis device connected to the inlet of the TOC deep oxidation module. The outlet of the block is connected to the inlet of the metal ion removal module via the precision filter; the metal ion removal module includes a three-layer composite resin layered filling structure, with an independent resin saturation sensor inside each resin layer; the metal ion removal module also includes a main tank and a backup tank, with an automatic switching valve group between the main tank and the backup tank; the halide ion control module includes a silver-loaded resin column and an online halide ion sensor, and the outlet of the halide ion control module is connected to the inlet of the electro-deionization device; the outlet of the electro-deionization device is connected to the polishing resin; the degassing protection module includes a nitrogen purging device and a vacuum degassing device, and the inlet of the degassing protection module is connected to the outlet of the polishing resin; a terminal filter is installed at the end of the anti-contamination delivery pipeline; the PLC controller is electrically connected to all sensors and actuators respectively.

[0019] Furthermore, the halide ion control module includes a main column and a backup column, with a single / dual column switching valve provided between the main column and the backup column, and the halide ion online sensor is located at the outlet end of the silver-loaded resin column.

[0020] Furthermore, the degassing protection module includes a nitrogen microporous disperser, an online dissolved oxygen sensor, a vacuum pump, and a vacuum degassing membrane assembly. The nitrogen microporous disperser is located at the water inlet of the degassing protection module, the vacuum degassing membrane assembly is connected to the vacuum pump, and the online dissolved oxygen sensor is located at the water outlet of the degassing protection module.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significant TOC deep removal effect: Through a three-stage combination process of ozone microbubbles, dual-wavelength ultraviolet light and ultrafiltration, the TOC removal rate is not less than 95%, and the TOC concentration in the effluent is stable below 1 ppb, which is far superior to the 5 ppb level of existing technologies.

[0022] 2. High precision in targeted removal of metal ions: Through a three-layer composite resin layered filling structure, the selectivity coefficient is 10 to 100 times higher than that of traditional single nuclear-level mixed bed resin, and the concentration of specific metal ions in the effluent is controlled at the ppt level.

[0023] 3. Halogen ion specific removal and dynamic adjustment: Chloride and bromide ions are precisely removed by silver-loaded resin, and the treatment effect and resin life are balanced by the single-column automatic switching logic.

[0024] 4. Degassing protection and pollution prevention during transport: The water is designed with a dual-mode system of nitrogen purging and vacuum degassing, ensuring that the dissolved oxygen in the effluent is no more than 3 ppb; the water quality at the point of use is guaranteed by using high-purity PVDF or PFA pipelines and an ultraviolet ozone circulation sterilization system.

[0025] 5. High precision intelligent control: Through isolated forest anomaly detection and consumable life prediction, proactive early warning and seamless switching are achieved, significantly improving the system's operational stability. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the overall process flow of the ultrapure water preparation method of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] Example 1 Reference Figure 1 This embodiment provides a method for preparing ultrapure water for cleaning perovskite solar cell substrates, and the specific steps are as follows: Step S1: Pass municipal tap water (raw water) through a quartz sand filter (containing quartz sand with a particle size of 0.5 to 1.2 mm, multi-layered) and an activated carbon filter (containing coconut shell activated carbon with an iodine value greater than 1000 mg / g). The quartz sand filter can remove suspended solids and colloidal particles with a particle size greater than 10 micrometers; the activated carbon filter can remove residual chlorine, organic matter and odor substances from the water, thereby reducing the turbidity of the pretreated water to below 0.5 NTU and the residual chlorine to less than 0.1 mg / L.

[0030] Step S2: The pretreated permeate is passed sequentially through a first-stage reverse osmosis unit (operating pressure 1.1 MPa, desalination rate 98.5%) and a second-stage reverse osmosis unit (operating pressure 1.0 MPa, desalination rate 99%). The conductivity of the second-stage reverse osmosis permeate is reduced to below 4 microsiemens per centimeter.

[0031] Step S3: Pass the secondary reverse osmosis permeate into the TOC deep oxidation module. This step is one of the core innovations of this embodiment, employing a three-stage combined process of ozone microbubbles, dual-wavelength ultraviolet light, and ultrafiltration. (1) Ozone microbubble enhanced mass transfer: Ozone with a dosage of 1 to 3 mg / L is introduced into the water in the form of microbubbles with an average diameter of no more than 50 micrometers. The microbubbles have a large specific surface area and a slow rising speed, which significantly improves the ozone utilization rate. Ozone decomposes in water to produce hydroxyl radicals. (2) 185 nm ultraviolet light generates hydroxyl radicals: 185 nm ultraviolet light can directly photolyze water molecules to generate hydroxyl radicals. The oxidation potential of hydroxyl radicals is as high as 2.8 V, which can non-selectively oxidize and decompose most organic matter. (3) Simultaneous sterilization with 254 nm ultraviolet light: 254 nm ultraviolet light has a sterilization effect, simultaneously inactivating microorganisms in the water and preventing microbial contamination of subsequent treatment units; (4) Ultrafiltration to retain oxidation products: By using an ultrafiltration membrane with a molecular weight of 5,000 to 10,000 Daltons to retain oxidation products and biological debris, the cleanliness of the effluent is ensured.

[0032] The four mechanisms described above work synergistically to achieve a TOC removal rate of no less than 95%, with the effluent TOC concentration stably controlled below 1 ppb. Simultaneously, the effluent TOC concentration is monitored in real-time by an online TOC sensor, and the ozone dosage and UV lamp power are dynamically adjusted based on the effluent TOC concentration to achieve adaptive regulation. The water residence time within the TOC deep oxidation module is 10 to 20 minutes.

[0033] Step S4: Pass the effluent from step S3 through a precision filter (pleated polypropylene filter cartridge) with an accuracy of 5 microns to trap any particulate matter that may be shed from the preceding unit, thus protecting the subsequent metal ion removal and electro-deionization units.

[0034] Step S5: Pass the effluent from Step S4 into the metal ion removal module. This step is another core innovation of this embodiment, employing a three-layer composite resin layered filling structure. The functional groups are optimized for transition metals, alkali metals, and heavy metals sensitive to perovskite solar cells, resulting in a selectivity coefficient 10 to 100 times higher than that of traditional single-nuclear-level mixed-bed resins. The specific structure is as follows: First layer (transition metal layer): filled with chelating resin containing chelating functional groups, which has targeted adsorption capacity for transition metal ions such as iron, lead, and chromium. The second layer (alkali metal layer) is filled with crown ether ketone resin containing crown ether ketone functional groups, which has targeted adsorption capacity for alkali metal ions such as sodium, potassium, and ammonium. The third layer (heavy metal layer): filled with aminophosphophosphate resin containing aminophosphophosphate functional groups, which has targeted adsorption capacity for heavy metal ions such as lead, cadmium, and mercury.

[0035] Furthermore, each resin layer is equipped with an independent resin saturation sensor to monitor the saturation status of each layer in real time. This allows for seamless switching between the main and backup tanks via an automatic switching valve assembly when any layer becomes saturated, while simultaneously sending a saturation warning. Based on this, compared to existing technologies that only allow for overall resin replacement without layer-by-layer monitoring, this embodiment achieves single-layer resin saturation warning and seamless switching between entire tanks.

[0036] Step S6: The effluent from Step S5 is passed into the halide ion control module. Specifically, this step uses a dedicated silver-loaded resin removal column, where chloride and bromide ions are precisely removed through a precipitation reaction between the silver-loaded resin and the chloride ion, with a removal capacity of not less than 1.0 mmol / g. Preferably, this embodiment is equipped with a high-sensitivity online halide ion sensor and an automatic single / dual column switching valve, which can dynamically adjust the treatment intensity according to the halide ion concentration in the effluent, balancing the treatment effect with resin lifespan.

[0037] Specifically, in this embodiment, the halide ion control logic is as follows: when the effluent halide ion concentration is no greater than 2 ppt, switch to single-column operation mode, with only the main column operating; when the effluent halide ion concentration is greater than 2 ppt but no greater than 5 ppt, maintain the current operation mode; when the effluent halide ion concentration is greater than 5 ppt, switch to dual-column series operation mode, with the main column and the standby column operating in series. Simultaneously, when the remaining resin life of the main column is no greater than 24 hours, automatically switch to standby column operation and send a replacement warning.

[0038] Step S7: Pass the effluent from Step S6 into an electro-deionization device (modular EDI module, homogeneous ion exchange membrane, palladium-coated iridium electrode, operating current 50 A). The resistivity of the effluent stabilizes above 18.2 megohm-cm (25 degrees Celsius). Then, it undergoes ion exchange polishing with nuclear-grade mixed-bed polishing resin, resulting in a total metal ion concentration in the effluent of no more than 1 ppt.

[0039] Step S8: The effluent from step S7 is passed into the degassing protection module for degassing treatment. This step is an innovative solution designed in this embodiment to address the stringent dissolved oxygen requirements of perovskite battery technology, employing a dual-mode design with nitrogen purging as the primary method and vacuum degassing as a secondary method. When the nitrogen pressure is not less than 0.2 MPa, the nitrogen purging mode is adopted: high-purity nitrogen is introduced into the water in the form of microbubbles through a nitrogen microporous disperser, and the gas-liquid partial pressure difference drives the dissolved oxygen in the water to transfer to the gas phase. The nitrogen flow rate is dynamically adjusted according to the dissolved oxygen concentration: when the dissolved oxygen concentration is greater than 3 ppb, the nitrogen flow rate is increased by 1 L / min; when the dissolved oxygen concentration is less than 1 ppb, the nitrogen flow rate is decreased by 1 L / min. The degassing efficiency of the nitrogen purging mode is not less than 95%.

[0040] When the nitrogen pressure falls below 0.2 MPa (nitrogen supply abnormality), the system automatically switches to vacuum degassing mode: the vacuum pump is activated to maintain a vacuum level of no more than 50 mbar, allowing dissolved gases in the water to precipitate under low pressure by reducing the system pressure. Simultaneously, a nitrogen supply abnormality warning is sent to ensure continuous and stable system operation. The vacuum degassing mode utilizes a vacuum degassing membrane module with a degassing efficiency of no less than 90%.

[0041] Step S9: The effluent from Step S8 is filtered through an ultrafiltration terminal filter with a molecular weight cutoff of 10,000 Daltons, and then transported to the point of use via a contamination-resistant pipeline. In this step, the contamination-resistant pipeline is made of high-purity PVDF material, with automatic track welding and an inner surface roughness Ra of 0.35 micrometers. The flow velocity within the pipeline is maintained at 1.8 meters per second. The UV-ozone circulating sterilization system performs intermittent ozone dosing twice per shift (dosing concentration 0.5 mg / L, lasting 30 minutes). A 0.1-micrometer terminal filter is installed at each point of use. The particulate matter (particle size greater than or equal to 0.1 micrometers) in the effluent from the point of use is less than 1 particle per milliliter.

[0042] Intelligent Control Steps: All the above steps are implemented through closed-loop control using a PLC controller. Specifically, this step mainly involves real-time acquisition of resistivity, TOC concentration, total metal ion concentration, total halide ion concentration, and dissolved oxygen concentration parameters by the PLC controller. An isolated forest algorithm is used to detect anomalies in the acquired data: when the anomaly score exceeds 0.8, an emergency switch is triggered, activating all backup modules; when the anomaly score exceeds 0.6, an early warning notification is sent. Simultaneously, a lifespan prediction model based on historical data is used to predict the remaining lifespan of each consumable. When the remaining lifespan of any consumable is no more than 24 hours, a replacement warning is sent.

[0043] Example 2 This embodiment provides an ultrapure water preparation system for cleaning perovskite solar cell substrates, which includes a pretreatment unit, a reverse osmosis desalination unit, a TOC deep oxidation module, a precision filter, a metal ion removal module, a halide ion control module, an electro-deionization device, a polishing resin, a degassing protection module, a contamination-proof delivery pipeline, and a PLC controller.

[0044] The pretreatment unit includes a quartz sand filter and an activated carbon filter, with the outlet of the quartz sand filter connected to the inlet of the activated carbon filter. The reverse osmosis desalination unit includes a primary reverse osmosis device and a secondary reverse osmosis device, with the outlet of the primary reverse osmosis device connected to the inlet of the secondary reverse osmosis device. The TOC deep oxidation module includes an ozone microbubble generator, a dual-wavelength ultraviolet device with wavelengths of 185 nm and 254 nm, an ultrafiltration membrane, a TOC online sensor, and a dynamic adjustment device. The outlet of the secondary reverse osmosis device is connected to the inlet of the TOC deep oxidation module. The outlet of the TOC deep oxidation module is connected to the inlet of the metal ion removal module via the precision filter. The TOC online sensor is located at the outlet of the ultrafiltration membrane. The dynamic adjustment device is electrically connected to the ozone microbubble generator and the dual-wavelength ultraviolet device, and dynamically adjusts the ozone dosage and ultraviolet lamp power based on the detection value of the TOC online sensor.

[0045] The metal ion removal module comprises a three-layer composite resin layered filling structure. From top to bottom, the three layers are a chelating resin layer, a crown ether resin layer, and an aminophosphate resin layer. The chelating resin layer is filled with chelating resin optimized for transition metal ions, the crown ether resin layer is filled with crown ether resin optimized for alkali metal ions, and the aminophosphate resin layer is filled with aminophosphate resin optimized for heavy metal ions. Furthermore, each resin layer is equipped with an independent resin saturation sensor. The metal ion removal module also includes a main tank and a backup tank, with an automatic switching valve assembly connecting the main tank and the backup tank.

[0046] The halide ion control module includes a silver-loaded resin column and an online halide ion sensor. The silver-loaded resin column includes a main column and a backup column, with a single / dual column switching valve between them. The online halide ion sensor is located at the outlet of the silver-loaded resin column. The outlet of the halide ion control module is connected to the inlet of the electro-deionization device; the outlet of the electro-deionization device is connected to the polishing resin. The degassing protection module includes a nitrogen microporous disperser, an online dissolved oxygen sensor, a vacuum pump, and a vacuum degassing membrane assembly. The nitrogen microporous disperser is located at the inlet of the degassing protection module, the vacuum degassing membrane assembly is connected to the vacuum pump, and the online dissolved oxygen sensor is located at the outlet of the degassing protection module. The anti-contamination delivery pipeline is made of high-purity PVDF or PFA material with an inner surface roughness Ra of no more than 0.4 micrometers. A 0.1-micrometer terminal filter is installed at the end of the anti-contamination delivery pipeline. The PLC controller is electrically connected to the sensors and actuators of each module.

[0047] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing ultrapure water for cleaning perovskite solar cell substrates, characterized in that, Includes the following steps: Step S1: The raw water is pretreated by passing it through a quartz sand filter and an activated carbon filter in sequence to remove suspended solids, colloidal particles and large molecular organic matter from the raw water; Step S2: The pretreated water is desalinated by passing it sequentially through a primary reverse osmosis unit and a secondary reverse osmosis unit. Step S3: Pass the secondary reverse osmosis permeate into the TOC deep oxidation module to first oxidize and degrade the organic matter in the water, and then use an ultrafiltration membrane to remove the oxidation products, so that the TOC concentration of the effluent is reduced to below 1 ppb. Step S4: Pass the effluent from step S3 into a precision filter, and discharge it after the particulate matter is removed by the precision filter; Step S5: The effluent from step S4 is fed into the metal ion removal module. The transition metal ions, alkali metal ions and heavy metal ions are removed sequentially through the three-layer composite resin layered filling structure. Each layer of resin is filled with chelating resin with functional groups optimized for the target metal ions. The saturation state of each layer of resin is monitored by an independent resin saturation sensor. When any layer of resin is saturated, the system automatically switches to the backup tank. Step S6: Pass the effluent from step S5 into the halide ion control module, remove chloride and bromide ions through silver-loaded resin, and dynamically adjust the treatment intensity according to the halide ion concentration in the effluent. Step S7: The effluent from step S6 is passed into an electro-deionization device for deep desalination, and then polished by ion exchange with polishing resin. Step S8: The effluent from step S7 is passed into the degassing protection module for degassing treatment. The degassing protection module operates in a dual mode, with nitrogen purging as the main method and vacuum degassing as the auxiliary method. Step S9: The effluent from step S8 is transported to the point of use through a pollution-proof conveying pipeline. The pollution-proof conveying pipeline is equipped with an ultraviolet and ozone circulation sterilization system that periodically adds ozone intermittently. Each point of use is equipped with a terminal filter.

2. The method for preparing ultrapure water for cleaning perovskite solar cell substrates according to claim 1, characterized in that, In step S3, hydroxyl radicals are generated through the synergistic effect of ozone microbubbles and dual-wavelength ultraviolet light with wavelengths of 185 nm and 254 nm to deeply oxidize and degrade organic matter in water. The dosage of ozone microbubbles is 1 to 3 mg / L, and the average diameter of the microbubbles is no more than 50 μm. The molecular weight cutoff of the ultrafiltration membrane is 5000 to 10000 Daltons. The residence time of water in the TOC deep oxidation module is 10 to 20 minutes. The TOC concentration of the effluent is monitored in real time by an online TOC sensor, and the ozone dosage and ultraviolet lamp power are dynamically adjusted according to the TOC concentration of the effluent.

3. The method for preparing ultrapure water for cleaning perovskite solar cell substrates according to claim 1, characterized in that, In step S5, the three-layer composite resin layered filling structure, from top to bottom, consists of: a chelating resin layer with functional groups optimized for transition metal ions, a crown ether ketone resin layer with functional groups optimized for alkali metal ions, and an aminophosphate resin layer with functional groups optimized for heavy metal ions; the chelating resin layer is filled with chelating resin containing chelating functional groups, the crown ether ketone resin layer is filled with crown ether ketone resin containing crown ether ketone functional groups, and the aminophosphate resin layer is filled with aminophosphate resin containing aminophosphate functional groups.

4. The method for preparing ultrapure water for cleaning perovskite solar cell substrates according to claim 1, characterized in that, In step S6, the control logic for dynamically adjusting the treatment intensity is as follows: when the effluent halide ion concentration is no greater than 2 ppt, switch to single-column operation mode, with only the main column working; when the effluent halide ion concentration is greater than 2 ppt but no greater than 5 ppt, maintain the current operation mode; when the effluent halide ion concentration is greater than 5 ppt, switch to dual-column series operation mode, with the main column and the standby column operating in series; when the remaining lifespan of the main column resin is no greater than 24 hours, automatically switch to standby column operation alone and send a replacement warning.

5. The method for preparing ultrapure water for cleaning perovskite solar cell substrates according to claim 1, characterized in that, In step S8, when the nitrogen pressure is not less than 0.2 MPa, the nitrogen purging mode is adopted and the nitrogen flow rate is dynamically adjusted according to the dissolved oxygen concentration. When the nitrogen pressure is less than 0.2 MPa, the system automatically switches to the vacuum degassing mode to reduce the dissolved oxygen content of the effluent to below 3 ppb. When the nitrogen purging mode is adopted, high-purity nitrogen is introduced into the water in the form of microbubbles through a nitrogen microporous disperser. When the dissolved oxygen concentration is greater than 3 ppb, the nitrogen flow rate is increased by 1 liter per minute. When the dissolved oxygen concentration is less than 1 ppb, the nitrogen flow rate is decreased by 1 liter per minute. When the vacuum degassing mode is adopted, the vacuum pump is started to maintain the vacuum degree not greater than 50 mbar and a nitrogen supply abnormality warning is sent.

6. The method for preparing ultrapure water for cleaning perovskite solar cell substrates according to claim 1, characterized in that, It also includes intelligent control steps: real-time acquisition of resistivity, TOC concentration, total metal ion concentration, total halide ion concentration and dissolved oxygen concentration parameters through PLC controller, and anomaly detection of the acquired data using the isolated forest algorithm: when the anomaly score exceeds 0.8, an emergency switch is triggered and all backup modules are activated, and when the anomaly score exceeds 0.6, an early warning notification is sent; at the same time, a lifespan prediction model based on historical data is used to predict the remaining lifespan of each consumable, and a replacement warning is sent when the remaining lifespan of any consumable is no more than 24 hours.

7. A system for preparing ultrapure water for cleaning perovskite solar cell substrates, comprising a pretreatment unit, a reverse osmosis desalination unit, an electro-deionization device, and a polishing resin, characterized in that, It also includes a TOC deep oxidation module, a precision filter, a metal ion removal module, a halide ion control module, a degassing protection module, a contamination-proof delivery pipeline, and a PLC controller; the pretreatment unit includes a quartz sand filter and an activated carbon filter, with the outlet of the quartz sand filter connected to the inlet of the activated carbon filter; the reverse osmosis desalination unit includes a primary reverse osmosis unit and a secondary reverse osmosis unit, with the outlet of the primary reverse osmosis unit connected to the inlet of the secondary reverse osmosis unit; the TOC deep oxidation module includes an ozone microbubble generator, a dual-wavelength ultraviolet device, and an ultrafiltration membrane, with the outlet of the secondary reverse osmosis unit connected to the inlet of the TOC deep oxidation module; the outlet of the TOC deep oxidation module is connected to the inlet of the metal ion removal module via the precision filter. The water end; the metal ion removal module includes a three-layer composite resin layered filling structure, with an independent resin saturation sensor inside each resin layer. The metal ion removal module also includes a main tank and a backup tank, with an automatic switching valve group between the main tank and the backup tank; the halide ion control module includes a silver-loaded resin column and an online halide ion sensor, with the outlet of the halide ion control module connected to the inlet of the electro-deionization device; the outlet of the electro-deionization device is connected to the polishing resin; the degassing protection module includes a nitrogen purging device and a vacuum degassing device, with the inlet of the degassing protection module connected to the outlet of the polishing resin; a terminal filter is installed at the end of the anti-pollution delivery pipeline; the PLC controller is electrically connected to all sensors and actuators respectively.

8. The ultrapure water preparation system for cleaning perovskite solar cell substrates according to claim 7, characterized in that, The halide ion control module includes a main column and a backup column, and a single / dual column switching valve is provided between the main column and the backup column. The halide ion online sensor is located at the outlet end of the silver-loaded resin column.

9. The ultrapure water preparation system for cleaning perovskite solar cell substrates according to claim 7, characterized in that, The degassing protection module includes a nitrogen microporous disperser, an online dissolved oxygen sensor, a vacuum pump, and a vacuum degassing membrane assembly. The nitrogen microporous disperser is located at the water inlet of the degassing protection module, the vacuum degassing membrane assembly is connected to the vacuum pump, and the online dissolved oxygen sensor is located at the water outlet of the degassing protection module.

Images