Ultrapure water purification system and purification method for removing trace hydrogen peroxide

Abstract

The invention relates to the technical field of pure water purification, in particular to an ultrapure water purification system and purification method for removing trace hydrogen peroxide. The ultrapure water purification system comprises an ultrapure water polishing system. The ultrapure water polishing system comprises a hydrogen peroxide removal device. The hydrogen peroxide removal device comprises a tank body, and a gas deflector, a catalyst resin layer and an inert resin layer which are arranged in the tank body, and adopts an up-flow mode to guide gas and flow out. The ultrapure water purification system comprises an ultrapure water preparation system. The ultrapure water preparation system comprises reverse osmosis equipment, a deionization security filter and deionization equipment. The pH value of the inlet water of the reverse osmosis equipment is controlled to be 9.5-10.5, and the pH value of the water produced by the reverse osmosis equipment is controlled to be 8.5-9.5. And the deionization security filter comprises an activated carbon filter element. And the deionization equipment comprises anion exchange resin. The concentration of dissolved oxygen entering the ultrapure water polishing system from the ultrapure water preparation system is controlled to be smaller than or equal to 10 ppb; the concentration of total organic carbon is less than or equal to 3ppb; the concentration of the hydrogen peroxide is less than or equal to 10ppb.

Description

Technical Field

[0001] This application relates to the technical field of pure water purification, and particularly relates to an ultrapure water purification system and purification method for removing trace hydrogen peroxide. Background Art

[0002] With the development of the electronics industry and the semiconductor industry, ultrapure water plays an increasingly important role in the manufacturing process. The quality of ultrapure water directly affects the manufacturing yield of semiconductor devices. Especially after the semiconductor enters the advanced manufacturing process, as the process line width shrinks, some trace components that were previously considered to have no impact on the manufacturing yield, such as active oxides, have also become key factors affecting the manufacturing yield.

[0003] Among the active oxides, hydrogen peroxide (H2O2) is one of the most representative substances. During the preparation process of ultrapure water, as a secondary pollutant, hydrogen peroxide has a particularly significant impact on the deterioration and damage of the materials in the downstream preparation units of ultrapure water. Especially in the later stages of the semiconductor process, scanning probe microscopy has revealed the pore corrosion phenomenon caused by this secondary oxide on the wafer surface. In view of this, the 2021 edition of the International Roadmap for Devices and Systems (IRDS) stipulates that the concentration limit standard of H2O2 in the cleaning water used for the 300mm wafer process manufacturing is not more than 3ppb.

[0004] How to effectively remove hydrogen peroxide from ultrapure water is a rather difficult technical problem. This is mainly attributed to two difficulties: firstly, hydrogen peroxide has a relatively long half-life and is not easily decomposed by itself; secondly, while removing trace-level (ppb-level) hydrogen peroxide from ultrapure water, it is necessary to avoid introducing other trace pollutants that are difficult to remove or have too high a re-removal cost. Only a technical solution that meets the above conditions can be considered appropriate and practical. Summary of the Invention

[0005] This application discloses an ultrapure water purification system and purification method for removing trace hydrogen peroxide to effectively remove trace hydrogen peroxide from ultrapure water.

[0006] To achieve the above object, this application provides the following technical solutions:

[0007] In a first aspect, the present application provides an ultrapure water purification system for removing trace hydrogen peroxide. The ultrapure water purification system includes an ultrapure water polishing system. The ultrapure water polishing system includes a secondary total organic carbon reduction ultraviolet device, a hydrogen peroxide removal device, and a polishing mixed bed. The hydrogen peroxide removal device is disposed between the secondary total organic carbon reduction ultraviolet device and the polishing mixed bed. The hydrogen peroxide removal device includes a tank body and a gas diverter, a catalyst resin layer, and an inert resin layer disposed inside the tank body. Among them, the tank body includes a water inlet and a water outlet. The water inlet is disposed at the bottom of the tank body, and the water outlet is disposed at the top of the tank body. The outlet of the gas diverter is communicated with the water outlet. The gas diverter is used to filter solid particles in the ultrapure water and allow gas to pass through. The inert resin layer is filled in the upper space inside the tank body, and the gas diverter is buried in the inert resin layer. The catalyst resin layer is used to catalyze the decomposition of hydrogen peroxide. The catalyst resin layer is located below the inert resin layer, and the density of the catalyst resin in the catalyst resin layer is greater than the density of the inert resin in the inert resin layer.

[0008] In the ultrapure water purification system of the present application, a hydrogen peroxide removal device is disposed between the secondary total organic carbon reduction ultraviolet device and the polishing mixed bed. After passing through the secondary total organic carbon reduction ultraviolet device, a certain amount of hydrogen peroxide will be generated in the ultrapure water. Among them, the hydrogen peroxide removal device adopts an upflow operation mode. The water inlet is disposed at the bottom of the tank body, and the water outlet is disposed at the top of the tank body, so that the pure water flows from bottom to top. Since the catalyst resin layer is located below the inert resin layer, and the density of the catalyst resin is greater than the density of the inert resin. When the pure water flows upward, the catalyst resin layer is lifted by the water flow and the inert resin layer is squeezed into the upper space inside the tank body. At the same time, the catalyst resin layer is in a freely floating state under the pressure of the inert resin layer, so that the catalyst resin is in a uniformly distributed fluidized state, effectively avoiding the phenomenon of uneven flow and short circuit in the catalyst resin layer, and further reducing the risk of violent reaction in the local area of the catalyst resin layer from the source, and reducing the concentrated release and escape of oxygen in the local area.

[0009] The hydrogen peroxide in the pure water is catalytically decomposed by the catalyst resin, and the generated oxygen gathers upward and is discharged through the diverter. Because the direction of oxygen gathering and escaping is the same as the water flow direction, the oxygen is carried out of the tank body by the water flow in the same direction and in the same process. Compared with the pure water flowing from top to bottom, the hydrogen peroxide removal device in the present application avoids the disadvantage that oxygen is partially retained in the tank body by the reverse impact of the water flow; moreover, after the inert resin is lifted by the water flow, it fills the upper space inside the tank body, thus squeezing the gathering and accumulation space of oxygen, so as to promote the oxygen to be discharged from the tank body through the gas diverter. In addition, after being blocked by the inert resin, the catalyst resin cannot contact the oxygen gathered near the gas diverter, effectively reducing the inhibitory effect of oxygen on the catalyst in the catalyst resin layer. Therefore, the ultrapure water purification system in the present application can effectively remove hydrogen peroxide without introducing new pollutants.

[0010] Further, the gas deflector is disposed at the top of the tank body and fits against the inner top wall of the tank body. The gas deflector includes a plurality of filter holes, and filter holes are provided at the top of the side wall of the gas deflector.

[0011] Further, the ultrapure water purification system includes an ultrapure water preparation system, and the ultrapure water preparation system is located upstream of the ultrapure water polishing system; the ultrapure water preparation system includes a deionization device, and the deionization device includes anion exchange resin.

[0012] Further, the ultrapure water preparation system further includes a primary total organic carbon reduction ultraviolet device and a deionization security filter. The deionization security filter is disposed between the primary total organic carbon reduction ultraviolet device and the deionization device, and the deionization security filter includes an activated carbon filter element.

[0013] Further, the ultrapure water preparation system further includes an ultraviolet lamp sterilization device, a reverse osmosis security filter, and a reverse osmosis device. The reverse osmosis security filter is located between the ultraviolet lamp sterilization device and the reverse osmosis device, and the ultraviolet lamp sterilization device is located upstream of the primary total organic carbon reduction ultraviolet device.

[0014] In a second aspect, the present application provides a purification method, and the purification method includes the following steps: introducing the pure water treated by the secondary total organic carbon reduction ultraviolet device into the hydrogen peroxide removal device. Among them, in the hydrogen peroxide device, the pure water sequentially passes through the catalyst resin layer and the inert resin layer from bottom to top and then flows out of the hydrogen peroxide removal device, and the oxygen generated by the decomposition of hydrogen peroxide is diverted outside the hydrogen peroxide removal device, and the catalyst resin in the catalyst resin layer and the inert resin in the inert resin layer are blocked from escaping.

[0015] Further, the purification method includes adding a pH regulator before the pure water enters the reverse osmosis device to make the pH of the water entering the reverse osmosis device 9.5 - 10.5, and the pH of the water produced by the reverse osmosis device is 8.5 - 9.5.

[0016] Further, the purification method includes introducing the pure water prepared by the ultrapure water preparation system into the ultrapure water polishing system. Among them, the concentration of dissolved oxygen entering the ultrapure water polishing system is controlled to be less than or equal to 10 ppb.

[0017] Further, the purification method includes introducing the pure water prepared by the ultrapure water preparation system into the ultrapure water polishing system. Among them, the concentration of total organic carbon entering the ultrapure water polishing system is controlled to be less than or equal to 3 ppb.

[0018] Further, the purification method includes introducing the pure water prepared by the ultrapure water preparation system into the ultrapure water polishing system. Among them, the concentration of hydrogen peroxide entering the ultrapure water polishing system is controlled to be less than or equal to 10 ppb. Description of the Drawings

[0019] Figure 1 Structural schematic diagram of an ultrapure water purification system according to an embodiment of the present application;

[0020] Figure 2 Structural schematic diagram of a hydrogen peroxide removal device according to an embodiment of the present application;

[0021] Figure 3 Structural schematic diagram of an ultrapure water purification system according to another embodiment of the present application.

[0022] Reference numerals in the drawings: 100 - ultrapure water polishing system; 110 - water tank; 120 - feed water pump; 130 - heat exchanger; 140 - secondary total organic carbon reduction ultraviolet device; 150 - hydrogen peroxide removal device; 151 - tank body; 152 - gas deflector; 153 - catalyst resin layer; 154 - inert resin layer; 155 - bottom water distributor; 156 - inlet pipe; 157 - inlet valve; 158 - outlet pipe; 159 - outlet valve; 160 - polishing mixed bed; 170 - secondary degassing membrane; 180 - terminal booster pump; 190a - terminal microfiltration device; 190b - terminal ultrafiltration device; 200 - ultrapure water preparation system; 210 - primary degassing membrane; 220 - preparation system microfiltration device; 230 - deionization equipment; 240 - deionization security filter; 250 - primary total organic carbon reduction ultraviolet device; 260 - deionization equipment feed water pump; 270 - RO water tank; 280 - RO equipment; 290 - high-pressure pump; 201 - RO security filter; 202 - ultraviolet lamp sterilization device; 203 - RO feed water pump; 300 - ultrapure water pretreatment system;

[0023] 01 - water inlet; 02 - water outlet; 03 - filter hole. Detailed implementation manners

[0024] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0025] The application scenarios described in the embodiments of the present application are to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those of ordinary skill in the art can know that with the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems. Among them, in the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more than two.

[0026] With the development of the electronics and semiconductor industries, the role of ultrapure water in the manufacturing process has become increasingly important. The quality of ultrapure water directly affects the manufacturing yield of semiconductor devices. Especially after the semiconductor industry enters the advanced process, as the process line width shrinks, some trace components that were previously considered not to affect the manufacturing yield, such as reactive oxides, have also become key factors affecting the manufacturing yield.

[0027] Among reactive oxides, hydrogen peroxide (H2O2) is one of the most representative substances. During the preparation process of ultrapure water, as a secondary pollutant, hydrogen peroxide has a particularly significant impact on the deterioration and damage of the materials in the downstream preparation units of ultrapure water. Especially in the later stages of the semiconductor process, scanning probe microscopy has revealed the pore corrosion phenomenon caused by this secondary oxide on the wafer surface. In view of this, the 2021 edition of the International Roadmap for Devices and Systems (IRDS) stipulates that the concentration limit standard of H2O2 in the cleaning water used for the 300mm wafer process manufacturing is not exceeding 3 ppb.

[0028] How to effectively remove hydrogen peroxide from ultrapure water is a rather tricky technical problem. This is mainly attributed to two difficulties: First, hydrogen peroxide has a relatively long half-life and is not easily decomposed by itself; second, while removing trace-level (ppb-level) hydrogen peroxide from ultrapure water, it is necessary to avoid introducing new trace pollutants that are difficult to remove or have too high a cost for re-removal. Only a technical solution that meets the above conditions can be considered suitable and practical.

[0029] Currently, there are many technical solutions for removing trace hydrogen peroxide from ultrapure water. However, among them, the main technical solutions with good practical test results are the technical solutions that use catalytic resin with noble metal (platinum, palladium, zirconium, etc.) catalysts to catalytically decompose hydrogen peroxide.

[0030] The noble metal catalyst catalytic resin (hereinafter referred to as catalytic resin) has become the current mainstream technical means in the industry mainly for the following two reasons: First, the alkaline conditions formed by the anion resin can effectively promote the decomposition of hydrogen peroxide. Second, while the noble metal catalyst effectively catalyzes the decomposition of hydrogen peroxide, it will not introduce new pollutants itself.

[0031] However, with the continuous popularization and application of catalytic resin in practice, some of its drawbacks have gradually emerged, mainly in the following aspects:

[0032] 1. Noble metal catalysts are prone to organic contamination, which can easily lead to premature deterioration of the catalytic ability of noble metal catalysts. The original organic matter and its secondary organic matter produced by the decomposition of ultraviolet (UV) light, such as organic acids, can cause contamination of noble metal catalysts and deterioration of their catalytic ability.

[0033] 2. Noble metal catalysts are prone to surface oxidation of the main body, which can easily lead to premature deterioration of the catalytic ability of noble metal catalysts. Ozone, hydroxyl radicals, hydrogen peroxide, and oxygen can all cause surface oxidation of noble metal catalysts and deterioration of their catalytic ability.

[0034] 3. Advanced semiconductor processes are relatively sensitive to H2O2, and the index requirements are relatively strict. The limit standard for the cleaning water used in the manufacturing process of 300mm wafers is that the concentration of H2O2 is less than or equal to 3 ppb. In many ultrapure water systems, the catalytic resin has exceeded the H2O2 index after only two or three months of use.

[0035] 3. Once the deterioration of noble metal catalysts is advanced, or the H2O2 index in ultrapure water exceeds the standard in advance, the replacement frequency of noble metal catalysts becomes higher. Since noble metal catalysts are expensive, the cost of manufacturing ultrapure water also increases accordingly.

[0036] 4. The catalytic resin with deteriorated catalytic performance usually needs to be operated offline to restore its performance. The operation process is time-consuming, laborious, and costly.

[0037] In view of this, an ultrapure water purification system is provided in an embodiment of the present application. Figure 1 It is a schematic structural diagram of an ultrapure water purification system according to an embodiment of the present application. Figure 2 It is a schematic structural diagram of a hydrogen peroxide removal device according to an embodiment of the present application. Please refer to Figure 1 and Figure 2, the ultrapure water purification system includes an ultrapure water polishing system 100. The ultrapure water polishing system 100 includes a secondary total organic carbon reduction ultraviolet device 140, a hydrogen peroxide removal device 150, and a polishing mixed bed 160. The hydrogen peroxide removal device 150 is disposed between the secondary total organic carbon reduction ultraviolet device 140 and the polishing mixed bed 160. The hydrogen peroxide removal device 150 includes a tank body 151 and a gas deflector 152, a catalyst resin layer 153, and an inert resin layer 154 disposed inside the tank body 151. Among them, the tank body 151 includes a water inlet 01 and a water outlet 02. The water inlet 01 is disposed at the bottom of the tank body 151, and the water outlet 02 is disposed at the top of the tank body 151. The outlet of the gas deflector 152 is communicated with the water outlet 02. The gas deflector 152 is used to filter solid particles in the ultrapure water and allow gas to pass through. The inert resin layer 154 is filled in the upper space inside the tank body 151, and the gas deflector 152 is buried in the inert resin layer 154. The catalyst resin layer 153 is used to catalyze the decomposition of hydrogen peroxide. The catalyst resin layer 153 is located below the inert resin layer 154, and the density of the catalyst resin in the catalyst resin layer 153 is greater than the density of the inert resin in the inert resin layer 154.

[0038] In some embodiments of the present application, the catalyst resin layer 153 includes an anion resin and a noble metal catalyst carried on the anion resin. Among them, the noble metal catalyst includes palladium (Pd), platinum (Pt), rhodium (Rh), gold (Au), etc.

[0039] It can be understood that the catalyst anion resin carrying the noble metal catalyst is used to accelerate the decomposition of H2O2, and its chemical reaction formula is as follows:

[0040] 2H2O2 = 2H2O + O2----------(Chemical reaction formula 1)

[0041] In addition, the device in the present application can also remove other trace oxidizing substances in the ultrapure water, such as ozone (O3) and hydroxyl radicals (·OH). The specific description is as follows:

[0042] ·OH is extremely unstable and will quickly transform into H2O2. The specific chemical reaction formula is as follows:

[0043] 2·OH = H2O2----------(Chemical reaction formula 2)

[0044] O3 decomposes rapidly in water. This decomposition process is an autocatalytic process, including the following steps:

[0045] B1. Adsorption and dissociation: O3 adsorbs and dissociates into ozone ions (O3 - );

[0046] B2. Ion reaction: The reaction between ozone ions (O3 - ) and water molecules (H2O) produces ·OH and oxygen molecules (O2);

[0047] B3. Autocatalytic reaction: The reaction between ·OH and O3 produces O2 and ·OH. This autocatalytic reaction is a key step in the whole process, which enables the continuous generation and consumption of ·OH in ozone water;

[0048] B4. Considering comprehensively the autocatalytic reaction of O3 in water and the conversion reaction of ·OH (see Reaction Formula 2), the decomposition reaction of ozone in high-purity water is mainly as follows.

[0049] O3 + H2O = H2O2 + O2----------(Chemical Reaction Formula 3)

[0050] In summary, the hydrogen peroxide removal device 150 in this application can not only remove H2O2, but also effectively remove O3 and ·OH. However, the hydrogen peroxide removal device 150 in this application focuses on removing hydrogen peroxide because O3 and ·OH in ultrapure water will also be converted into H2O2. Therefore, it is relatively reasonable to focus on removing H2O2 when removing trace oxidizing substances in ultrapure water.

[0051] It should be noted that in some semiconductor manufacturing processes, when there is no extremely stringent requirement for the concentration of hydrogen peroxide, the catalyst resin layer 153 may include anion resin without noble metal catalyst.

[0052] In some embodiments of this application, the gas deflector 152 is arranged at the top of the tank body 151 and is attached to the inner top wall of the tank body 151. The gas deflector 152 includes a plurality of filter holes 03. The filter holes 03 allow gas to pass through. The top of the side wall of the gas deflector 152 is provided with the filter holes 03, so that the O2 rising to the inner top area of the tank body 151 can be discharged through the filter holes 03 in time, reducing or avoiding the probability of O2 accumulation in this area.

[0053] In some embodiments of this application, the aperture of the filter holes 03 is smaller than the particle sizes of the inert resin and the catalyst resin, so that the inert resin and the catalyst resin cannot pass through the filter holes 03, thereby avoiding the waste caused by the discharge of the inert resin or the catalyst resin out of the tank body 151 along with the water flow.

[0054] It can be understood that the shape of the filter holes 03 is not limited in this application. The shape of the filter holes 03 can be circular, triangular or strip-shaped, etc. Exemplarily, the filter holes 03 can be slits.

[0055] In some embodiments of this application, the gas deflector 152 includes at least one of a sieve tube and a water cap plate. Among them, as Figure 2 shown, the gas deflector 152 can be a sieve tube.

[0056] In a large water volume system, the gas diverter 152 can be a water cap perforated plate, which can distribute water more evenly, with better effect and fewer dead corners.

[0057] In some embodiments of the present application, the device for removing hydrogen peroxide from ultrapure water further includes a lower water distributor 155, and the inlet of the lower water distributor 155 is communicated with the water inlet 01. The function of the lower water distributor 155 is to make the inlet water flow into the tank body 151 more evenly, and prevent the local catalytic reaction of the catalyst resin layer 153 from being too intense, causing the concentrated release and escape of oxygen.

[0058] Wherein, the lower water distributor 155 can be a lower sieve tube or the like.

[0059] In some embodiments of the present application, the hydrogen peroxide removal device 150 further includes a water inlet pipe 156 and a water inlet valve 157. The water inlet pipe 156 is communicated with the water inlet 01, and the water inlet valve 157 is arranged on the water inlet pipe 156 or between the water inlet pipe 156 and the water inlet 01. The water inlet valve 157 can be fully opened or closed to allow or prevent water flow into the tank body 151, so as to control the operation and stop of the entire system.

[0060] In some embodiments of the present application, the hydrogen peroxide removal device 150 further includes a water outlet pipe 158 and a water outlet valve 159. The water outlet pipe 158 is communicated with the water outlet 02, and the water outlet valve 159 is arranged on the water outlet pipe 158 or between the water outlet pipe 158 and the water outlet 02. The water outlet valve 159 can be fully opened or closed to allow or prevent water flow out of the tank body 151.

[0061] Because it includes the hydrogen peroxide removal device 150 in the present application, this ultrapure water purification system has the following

[0062] Beneficial effects:

[0063] 1) Adopting an upflow process, making the water flow direction consistent with the O2 escape and aggregation direction, can enable O2 to be quickly and timely discharged from the gas diverter 152 to the outside of the tank body 151 along with the water flow, thereby avoiding the adverse effects caused by the accumulation of O2 in the top area inside the tank body 151, and can avoid and slow down reaction inhibition and catalytic performance deterioration;

[0064] 2) Adopting an upflow process can make the catalyst resin in a freely floating state, similar to a fluidized state, and the catalyst and H2O2 can contact each other more fully, thereby better improving the catalytic effect and reaction speed;

[0065] 3) It can improve and reduce the operation head loss, reduce energy consumption, and can reduce the size of the resin tank body 151, reduce the amount of catalyst resin used, thereby reducing the overall volume for removing hydrogen peroxide from ultrapure water.

[0066] Among them, the secondary total organic carbon ultraviolet device 140 is used to degrade and reduce bacterial growth and eliminate organic matter. The polishing mixed bed 160 is used to remove trace ion residues, improve the resistivity, and remove silicon and boron.

[0067] Continue to refer to Figure 1 , the ultrapure water polishing system 100 in the embodiment of the present application further includes a secondary degassing membrane 170. The secondary degassing membrane 170 can deoxygenate and remove permeating gas. The secondary degassing membrane 170 is located downstream of the polishing mixed bed 160.

[0068] It can be understood that after the ultrapure water (Ultra-Pure Water, UPW) passes through the hydrogen peroxide removal device 150 and the polishing mixed bed 160, the state of the oxygen generated by the decomposition of hydrogen peroxide may be in a dissolved state, a fine bubble state, or a mixed state of the two. Among them, no matter which state the oxygen generated by the decomposition of hydrogen peroxide is in, after being superimposed with the original dissolved oxygen (Dissolved Oxygen, DO) in the water, it can be effectively reduced by the subsequent secondary degassing membrane 170, so as to meet the DO index requirements at the point of use (POU) of the ultrapure water.

[0069] In some embodiments of the present application, the ultrapure water polishing system 100 further includes a water tank 110, a feed water pump 120, and a heat exchanger 130. Among them, the feed water pump 120 is arranged between the water tank 110 and the heat exchanger 130, and the heat exchanger 130 is located upstream of the secondary total organic carbon ultraviolet device 140.

[0070] Optionally, the heat exchanger 130 is used to adjust the temperature of the ultrapure water to within a set threshold range before supply.

[0071] In some embodiments of the present application, the ultrapure water polishing system 100 further includes a terminal booster pump 180, a terminal microfiltration device 190a, and a terminal ultrafiltration device 190b located downstream of the secondary degassing membrane 170. Among them, the terminal booster pump 180 is used for further boosting. The terminal microfiltration device 190a and the terminal ultrafiltration device 190b can filter out particles in the water and have good characteristics for removing organic matter. The terminal ultrafiltration device 190b can also filter out the total organic carbon (Total Organic Carbon, TOC) in the ultrapure water.

[0072] In some embodiments of the present application, the ultrapure water purification system includes an ultrapure water preparation system 200, and the ultrapure water preparation system 200 is located upstream of the ultrapure water polishing system 100. The ultrapure water preparation system 200 is used to prepare ultrapure water.

[0073] Figure 3 For the structural schematic diagram of the ultrapure water purification system in another embodiment of the present application, refer to Figure 3, the ultrapure water preparation system 200 may include a deionization device 230. Among them, the deionization device 230 includes anion resin, and a slightly alkaline environment is formed on the surface of the anion resin to promote the decomposition of H2O2.

[0074] In some embodiments of the present application, the deionization device 230 may adopt a two-chamber bed, a mixed bed, electrodeionization (EDI), or other devices containing anion exchange resin. Preferably, the water flow first passes through the two-chamber bed process of the anion resin because the alkaline environment it provides for decomposing H2O2 is the best among the above several process devices.

[0075] In some embodiments of the present application, the ultrapure water preparation system 200 may include a deionization device water supply pump 260 and a primary total organic carbon reduction ultraviolet device 250. Among them, the primary total organic carbon reduction ultraviolet device 250 is located between the deionization device 230 and the deionization device water supply pump 260. The primary total organic carbon reduction ultraviolet device 250 is used to degrade and reduce bacterial growth and reduce organic matter.

[0076] In some embodiments of the present application, the ultrapure water preparation system 200 further includes a deionization security filter 240. The deionization security filter 240 is arranged between the primary total organic carbon reduction ultraviolet device 250 and the deionization device 230. The deionization security filter 240 includes an activated carbon filter element.

[0077] Among them, the deionization security filter 240 may select an activated carbon / polypropylene (PP) composite filter element.

[0078] In some embodiments of the present application, the ultrapure water preparation system 200 further includes a preparation system microfiltration device 220 and a primary degassing membrane 210 located downstream of the deionization device 230. Among them, the preparation system microfiltration device 220 is used to remove impurities such as suspended particles, bacteria, and some colloids in the water. The primary degassing membrane 210 can deoxygenate and remove permeating gas.

[0079] In some embodiments of the present application, the ultrapure water preparation system 200 further includes a reverse osmosis (RO) water tank 270 located upstream of the deionization device water supply pump 260.

[0080] In some embodiments of the present application, the ultrapure water preparation system 200 further includes an ultraviolet lamp sterilization device 202, an RO security filter 201, and an RO device 280. The RO security filter 201 is located between the ultraviolet lamp sterilization device 202 and the RO device 280, and the ultraviolet lamp sterilization device 202 is located upstream of the primary total organic carbon reduction ultraviolet device 250.

[0081] Among them, the ultraviolet lamp sterilization device 202 uses ultraviolet radiation to destroy the DNA structure of microorganisms in water, thereby killing or inactivating bacteria, viruses and other pathogens in water. The RO pre-filter 201 is a pretreatment step before the reverse osmosis system. Its main function is to remove suspended solids, particulate matter, turbidity and most microorganisms in water to protect the reverse osmosis membrane from pollution and damage. The RO device 280 is the core part of the ultrapure water preparation system 200. It applies pressure to water through a semi-permeable membrane, allowing water molecules to pass through the membrane while most dissolved salts, organic matter, microorganisms and other impurities are intercepted.

[0082] In some embodiments of the present application, the ultrapure water preparation system 200 further includes a high-pressure pump 290 disposed between the RO device 280 and the RO pre-filter 201.

[0083] In some embodiments of the present application, the ultrapure water preparation system 200 further includes an RO feed pump 203 located upstream of the ultraviolet lamp sterilization device 202.

[0084] In some embodiments of the present application, the ultrapure water purification system includes an ultrapure water pretreatment system 300, and the ultrapure water pretreatment system 300 is located upstream of the ultrapure water preparation system 200. The ultrapure water pretreatment system 300 pre-treats the incoming water to prepare for the next step of preparing ultrapure water, and the pre-treated water enters the ultrapure water preparation system 200.

[0085] It should be noted that according to different water quality requirements, the above ultrapure water purification system can also have various different deformations. For example, the configuration level of some devices can be increased, or the positions of some devices can be changed, or some devices can also be combined with other process equipment in series, parallel, series-parallel, carousel and other ways.

[0086] Among them, the carousel refers to a cyclic usage mode of a device or apparatus, similar to the movement mode of a carousel, that is, after the device or apparatus completes one cycle of operation, it will return to the starting point to start the next cycle, forming a continuous and cyclic work process.

[0087] Based on the same technical concept, an embodiment of the present application also provides a purification method, and the purification method includes the following steps:

[0088] Introduce the pure water treated by the two-stage total organic carbon reduction ultraviolet device into the hydrogen peroxide removal device. Among them, in the hydrogen peroxide device, the pure water flows through the catalyst resin layer and the inert resin layer from bottom to top in sequence and then flows out of the hydrogen peroxide removal device, and the oxygen generated by decomposing hydrogen peroxide is guided out of the hydrogen peroxide removal device, and the catalyst resin in the catalyst resin layer and the inert resin in the inert resin layer are blocked from escaping.

[0089] In the above purification method, pure water flows from bottom to top, the catalytic resin layer is lifted by the water flow, and the inert resin layer is squeezed into the upper space within the hydrogen peroxide removal device. At the same time, the catalytic resin layer is in a free floating state under the pressure of the inert resin layer, so that the catalytic resin is uniformly fluidized, thereby effectively avoiding the occurrence of biased flow and short-flow in the catalytic resin layer, thereby reducing the risk of violent reaction in local areas of the catalytic resin layer from the source, and reducing the concentrated release and escape of oxygen in local areas. In addition, the hydrogen peroxide in the pure water is catalytically decomposed by the catalytic resin, and the generated oxygen is gathered upward and directed to the outside of the hydrogen peroxide removal device. Because the direction of oxygen accumulation and escape is consistent with the direction of water flow, the oxygen is carried out by the water flow in the same direction and flow to the outside of the hydrogen peroxide removal device. Compared with pure water flowing from top to bottom, the hydrogen peroxide removal device in this application avoids the disadvantage of oxygen being partially retained in the tank body by the reverse impact of the water flow; moreover, the inert resin is lifted by the water flow and fills the upper space within the hydrogen peroxide removal device, thereby occupying the space for oxygen accumulation and storage, thereby promoting the discharge of oxygen. Therefore, the purification method in the present application can achieve effective removal of hydrogen peroxide without introducing new pollutants.

[0090] It is understood that the main factors affecting the generation of H2O2 under ultraviolet light include the wavelength and intensity of ultraviolet light, reaction time and pH value of the reaction system. - ) is the main factor that inhibits the generation of H2O2. When pH=10, OH - The absorbance at 185 nm (0.31 cm -1 ) is only 17% of the water absorbance, while the amount of H2O2 produced decreases by 68.4%. Therefore, it is generally believed that OH - The influence of light shielding is small, and its quenching of ·OH is the main reason for inhibiting the formation of H2O2.

[0091] In an alkaline environment, the stability of H2O2 is significantly reduced. Under high pH conditions, H2O2 is more likely to decompose, producing O2 and H2O (see chemical reaction formula 3). This is because the alkaline environment is conducive to the decomposition reaction, accelerating the decomposition process of H2O2.

[0092] In summary, there's a close relationship between the stability of H2O2 and its pH. The stability of H2O2 can be controlled by adjusting the pH of the solution. For example, if H2O2 activity needs to be maintained for a long time, the pH can be lowered by adding an appropriate amount of acid, thereby improving its stability. Conversely, if rapid O2 release is desired, the pH can be appropriately increased to accelerate its decomposition.

[0093] H2O2 is most unstable under alkaline conditions (pH = 9 - 10) and easily decomposes into water and oxygen. Under acidic conditions (pH = 3.5 - 4.5), hydrogen peroxide is relatively stable. This difference in stability also reflects the acidic properties of H2O2.

[0094] Ozone, hydrogen peroxide, oxygen, and hydroxyl radicals all have the characteristic of rapid decomposition under alkaline conditions. Among them, in order to promote the rapid decomposition of the above-mentioned oxidizing substances, the pH value in the ultrapure water preparation system is 7 - 10.5.

[0095] In some embodiments of the present application, a pH regulator is added before the pure water enters the RO device to make the influent pH of the RO device 9.5 - 10.5, which is greater than the equilibrium point pH = 8.3 of the total ionization of carbonic acid, so as to achieve a better degree of ion conversion and facilitate the subsequent deionization device to have a better removal effect on carbonic acid, carbonate ions, and bicarbonate ions.

[0096] The effluent pH of the RO device is 8.5 - 9.5. Within this pH range, the ionization degree of silicic acid and boric acid is maximized, which is convenient for the subsequent deionization device to achieve a better boron and silicon removal effect.

[0097] In addition, adding a pH regulator before the RO device to make the influent pH of the RO device 9.5 - 10.5 can achieve an excellent effect of removing chloramines and reduce the oxidation risk of the deionization device and other downstream polymer material devices.

[0098] In some embodiments of the present application, the pure water prepared by the ultrapure water preparation system is introduced into the ultrapure water polishing system, wherein the concentration of dissolved oxygen (DO) entering the ultrapure water polishing system is controlled to be less than or equal to 10 ppb.

[0099] Specifically, the DO concentration in the effluent of the first-stage degassing membrane of the ultrapure water preparation system can be controlled to be less than or equal to 10 ppb to effectively reduce the DO concentration.

[0100] The above technical measures are mainly based on the following technical factors:

[0101] 1) High DO concentration will inhibit the decomposition of H2O2. Referring to Chemical Reaction Equation 3, O2 is on the right side of the chemical reaction equation. High DO concentration promotes the left shift of the chemical equilibrium of Chemical Reaction Equation 3, which will inhibit the decomposition reaction of H2O2, resulting in a worse effect of decomposing and removing H2O2. The higher the DO concentration entering the ultrapure water polishing system from the ultrapure water preparation system, the higher the degree of inhibition of H2O2 decomposition, especially in the hydrogen peroxide removal device of the ultrapure water polishing system.

[0102] According to Chemical Reaction Formula 3, when H2O2 with a concentration of 34 ppb decomposes, it produces O2 with a concentration of 16 ppb. That is to say, the generated O2 is close to half of the H2O2. Therefore, theoretically, a DO concentration of 1 ppb entering the ultra-pure water polishing system from the ultra-pure water preparation system is approximately equivalent to the O2 generated by decomposing 2 ppb of H2O2 in the ultra-pure water polishing system. The actual degree of inhibition of DO concentration on the decomposition of H2O2 will be affected by many factors, such as temperature, chemical equilibrium constant, etc., which will not be elaborated here.

[0103] According to practical experience, generally, when the H2O2 concentration is greater than 30 ppb, the degree of oxidation on the catalyst surface will increase significantly. Considering the inhibitory effect of DO concentration on the decomposition of H2O2 and the oxidation effect of H2O2 on the catalyst surface, the H2O2 concentration should be kept below 30 ppb as much as possible.

[0104] 2) High DO concentration will accelerate the surface oxidation of the noble metal catalyst and the deterioration of its catalytic ability, gradually causing it to lose its catalytic ability. Reducing the DO concentration entering the ultra-pure water polishing system, thereby reducing the background O2 concentration entering the hydrogen peroxide removal device, helps to reduce the speed and degree of catalyst deterioration from the source.

[0105] In summary, the DO concentration in the pure water entering the ultra-pure water polishing system from the ultra-pure water preparation system should be reduced as much as possible. Of course, the cost should be weighed at the same time, rather than reducing it infinitely. After technical and economic analysis, the DO concentration limit entering the ultra-pure water polishing system should be determined through comprehensive consideration. Considering that the concentration of H2O2 generated by the secondary total organic carbon reduction ultraviolet device is usually greater than 22 ppb, and the equivalent DO concentration after its decomposition is greater than 10 ppb, combined with the experience of economic and technical analysis, the preferred control target for entering the ultra-pure water polishing system is that the DO concentration is less than or equal to 10 ppb.

[0106] It should be noted that the concentration of H2O2 generated by the secondary total organic carbon reduction ultraviolet device is related to the TOC removal load it undertakes. Here, it is considered that the secondary total organic carbon reduction ultraviolet device in the ultra-pure water polishing system undertakes at least the removal of 2 ppb of TOC load.

[0107] In some embodiments of the present application, the concentration of total organic carbon entering the ultra-pure water polishing system is controlled to be less than or equal to 3 ppb. Among them, controlling the concentration of total organic carbon entering the ultra-pure water polishing system within the above range is mainly based on the following technical factors:

[0108] First, by reducing the TOC removal burden of the ultrapure water polishing system, the generation of H2O2 in the ultrapure water polishing system can be significantly reduced. Among them, the concentration of H2O2 generated by the secondary TOC reduction ultraviolet device is related to the TOC removal load it undertakes. According to practical experience, when the TOC reduction load of the ultrapure water polishing system exceeds 2 ppb, the H2O2 generated by the secondary TOC reduction ultraviolet device generally exceeds 22 ppb.

[0109] Therefore, if the ultrapure water preparation system undertakes more TOC removal tasks, the TOC removal burden in the ultrapure water polishing system can be effectively reduced, thereby significantly reducing the generation of H2O2 in the ultrapure water polishing system, and thus reducing the working burden of the hydrogen peroxide removal device.

[0110] Generally, after the H2O2 concentration is greater than 30 ppb, the degree of oxidation on the catalyst surface will begin to increase significantly. Technically, the TOC removal load of the secondary TOC reduction ultraviolet device can be reasonably controlled, and appropriate technical measures can be taken in the preparation system to remove the H2O2 generated by the primary TOC reduction ultraviolet device, so that the concentration of residual H2O2 in the product water of the ultrapure water preparation system, after superimposing the newly generated H2O2 in the ultrapure water polishing system, is as small as possible less than 30 ppb.

[0111] Second, a high TOC concentration will accelerate the deterioration of the catalytic ability of the noble metal catalyst, causing it to gradually lose its catalytic ability. Reducing the TOC concentration entering the ultrapure water polishing system and reducing the content of background organic matter entering the hydrogen peroxide removal device helps to reduce the rate and degree of catalyst performance deterioration from the source.

[0112] In some embodiments of the present application, the concentration of hydrogen peroxide entering the ultrapure water polishing system is controlled to be less than or equal to 10 ppb.

[0113] Among them, the H2O2 entering the hydrogen peroxide removal device has two sources. One part is newly generated by the secondary TOC reduction ultraviolet device, and the other part is transferred from the ultrapure water preparation system. It can be understood that to control the H2O2 concentration entering the hydrogen peroxide removal device, measures should be taken from the above two aspects.

[0114] First, in the purification method of the present application, the concentration of total organic carbon entering the ultrapure water polishing system is controlled to be less than or equal to 3 ppb, that is, the TOC removal burden in the ultrapure water polishing system is reduced, and more of the TOC removal burden is transferred to the ultrapure water preparation system.

[0115] Secondly, reduce the concentration of H2O2 entering the ultrapure water polishing system from the ultrapure water preparation system. Specifically, control the concentration of hydrogen peroxide entering the ultrapure water polishing system to be less than or equal to 10 ppb. To control the concentration of hydrogen peroxide within the above range, the purification method in this application further includes:

[0116] A. Increase the pH value in the ultrapure water preparation system to promote the decomposition of H2O2.

[0117] B. Form a slightly alkaline environment on the surface of the anion resin in the deionization device to promote the decomposition of H2O2. Preferably, the water flow first passes through the double-chamber bed process of the anion resin.

[0118] C. Optionally, a deionization security filter can be set between the deionization device and the first-stage total organic carbon reduction ultraviolet device.

[0119] Among them, the deionization security filter includes an activated carbon filter element, preferably an activated carbon / polypropylene (PP) composite filter element. Activated carbon can significantly and effectively reduce the concentration of H2O2 generated by the first-stage total organic carbon reduction ultraviolet device entering the deionization device. The use of an activated carbon filter should be avoided because the loose activated carbon in the activated carbon filter is prone to a large amount of disintegration at this position, causing a greater particle risk, and it is also prone to a risk of bacterial growth. In addition, the activated carbon of the filter element set at this process position should preferably use compressed activated carbon, and loose activated carbon should be avoided as much as possible. Considering that the catalytic effect of activated carbon is mainly utilized here, the proportion of activated carbon in the activated carbon / PP composite filter element should be as small as possible.

[0120] The principle of activated carbon catalyzing the decomposition of H2O2 is mainly based on its high specific surface area and the role of surface functional groups. Activated carbon has a very large specific surface area, which can provide a large number of active sites to promote the decomposition reaction of H2O2. In addition, surface functional groups on the surface of activated carbon, such as carboxyl groups, lactones, phenols, and carbonyl groups, also play a catalytic role in the decomposition of H2O2. These functional groups can interact with H2O2 and reduce the difficulty of the decomposition reaction.

[0121] Activated carbon is suitable for application in the ultrapure water preparation system. An activated carbon filter element is set after the first-stage total organic carbon reduction ultraviolet device, and an activated carbon / PP composite filter element is preferably used to control the degree and amount of disintegration of activated carbon to avoid affecting the performance of subsequent process equipment. Before entering the ultrapure water polishing system, a small amount of disintegrated activated carbon should be processed by subsequent process equipment in the ultrapure water preparation system and reduced to an acceptable level for the ultrapure water polishing system.

[0122] The catalytic effect of activated carbon on the decomposition of H2O2 can even rival that of noble metal catalysts in some specific cases, and it has an extremely obvious cost advantage. Theoretically, if activated carbon can be applied in the ultrapure water polishing system to replace expensive noble metal catalysts, it will create great economic benefits. However, current practical experience shows that activated carbon is not suitable for use in the ultrapure water polishing system. The main reasons are as follows: First, the various indicators of the ultrapure water polishing system are more stringent, and the disintegrated activated carbon has an adverse impact on these stringent indicators in the polishing system. For example, the ultrapure water polishing system has strict particle index requirements and is extremely sensitive to the fine particles produced by the disintegration of activated carbon. The degree of disintegration that can be accepted in the ultrapure water preparation system is unacceptable in the ultrapure water polishing system. Second, it is extremely easy to cause associated pollution when dealing with disintegrated activated carbon in the ultrapure water polishing system, and the application cost is too high. For example, the goal of controlling bacteria in the ultrapure water polishing system is very strict. If activated carbon is used, the risk of bacterial growth increases, which easily causes the bacterial index of the ultrapure water polishing system to exceed the standard, and the associated TOC index and particle index also exceed the standard.

[0123] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Claims

1. An ultrapure water purification system for removing trace hydrogen peroxide, characterized in that, The ultra-pure water purification system includes an ultra-pure water polishing system; The ultra-pure water polishing system includes a secondary total organic carbon reduction ultraviolet device, a hydrogen peroxide removal device, and a polishing mixed bed. The hydrogen peroxide removal device is disposed between the secondary total organic carbon reduction ultraviolet device and the polishing mixed bed; The hydrogen peroxide removal device includes a tank body and a gas flow guide, a catalyst resin layer, and an inert resin layer disposed in the tank body. Wherein, the tank body includes a water inlet and a water outlet. The water inlet is disposed at the bottom of the tank body, and the water outlet is disposed at the top of the tank body. The outlet of the gas flow guide is communicated with the water outlet. The gas flow guide is used to filter solid particles in the ultra-pure water and allow gas to pass through. The inert resin layer is filled in the upper space in the tank body, and the gas flow guide is buried in the inert resin layer. The catalyst resin layer is used to catalyze the decomposition of hydrogen peroxide. The catalyst resin layer is located below the inert resin layer, and the density of the catalyst resin in the catalyst resin layer is greater than the density of the inert resin in the inert resin layer.

2. The ultrapure water purification system according to claim 1, wherein The gas flow guide is disposed at the top of the tank body and is attached to the inner top wall of the tank body. The gas flow guide includes a plurality of filter holes, and the filter holes are disposed at the top of the side wall of the gas flow guide.

3. The ultrapure water purification system according to claim 1, wherein The ultra-pure water purification system includes an ultra-pure water preparation system, and the ultra-pure water preparation system is located upstream of the ultra-pure water polishing system. The ultra-pure water preparation system includes a deionization device, and the deionization device includes an anion exchange resin.

4. The ultrapure water purification system according to claim 3, characterized in that, The ultra-pure water preparation system further includes a primary total organic carbon reduction ultraviolet device and a deionization security filter. The deionization security filter is disposed between the primary total organic carbon reduction ultraviolet device and the deionization device. The deionization security filter includes an activated carbon filter element.

5. The ultrapure water purification system according to claim 4, wherein, The ultra-pure water preparation system further includes an ultraviolet lamp sterilization device, a reverse osmosis security filter, and a reverse osmosis device. The reverse osmosis security filter is located between the ultraviolet lamp sterilization device and the reverse osmosis device, and the ultraviolet lamp sterilization device is located upstream of the primary total organic carbon reduction ultraviolet device.

6. A purification method for ultrapure water for removing trace hydrogen peroxide, characterized in that, Including the following steps: Introduce the pure water treated by the secondary total organic carbon reduction ultraviolet device into the hydrogen peroxide removal device. Wherein, in the hydrogen peroxide device, the pure water sequentially passes through the catalyst resin layer and the inert resin layer from bottom to top and then flows out of the hydrogen peroxide removal device, and the oxygen generated by the decomposition of hydrogen peroxide is guided out of the hydrogen peroxide removal device, and the catalyst resin in the catalyst resin layer and the inert resin in the inert resin layer are blocked from escaping.

7. The purification method according to claim 6, wherein The purification method includes: adding a pH regulator before the pure water enters the reverse osmosis device to make the pH of the water inlet of the reverse osmosis device 9.5 - 10.5, and the pH of the produced water of the reverse osmosis device 8.5 - 9.

5.

8. The purification method according to claim 6, wherein The purification method includes: introducing the pure water prepared by the ultra-pure water preparation system into the ultra-pure water polishing system. Wherein, the concentration of dissolved oxygen entering the ultra-pure water polishing system is controlled to be less than or equal to 10 ppb.

9. The purification method according to claim 6, characterized in that, Introduce the pure water produced by the ultrapure water preparation system into the ultrapure water polishing system, wherein the concentration of total organic carbon entering the ultrapure water polishing system is controlled to be less than or equal to 3 ppb.

10. The purification method according to claim 6, characterized in that, Introduce the pure water produced by the ultrapure water preparation system into the ultrapure water polishing system, wherein the concentration of hydrogen peroxide entering the ultrapure water polishing system is controlled to be less than or equal to 10 ppb.

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