Method for finely treating ion exchange resin by using micro-nano bubble water

Abstract

The invention discloses a method for finely treating ion exchange resin by using micro-nano bubble water, which comprises the following steps: (1) preparing carbon dioxide functional water in a gas-liquid mixing unit: respectively inputting deionized water with the temperature of 15-20 DEG C and the pressure of 0.61-1.01 MPa and liquid carbon dioxide with the temperature of-20-20 DEG C and the pressure of 3.04-8.11 MPa into the gas-liquid mixing unit, saturated carbon dioxide functional water is formed under the condition that the pressure is 0.61-1.01 MP; (2) micro-nano bubble water is prepared in a micro-nano bubble generation unit, the micro-nano bubble generation unit is composed of two stages of Venturi structures, the taper angle of a diffusion pipe section of each Venturi structure is 15-25 degrees, and the carbon dioxide functional water forms the micro-nano bubble water with the average particle size of nano micro bubbles being 0.08-1 micron through the micro-nano bubble generation unit; and (3) the micro-nano bubble water is injected into the resin tank filled with the ion exchange resin from the bottom of the resin tank at the flow speed of 50-70 BV / h, the cleaning amount is 100-300 BV, and cleaning of the ion exchange resin is completed.

Description

Technical Field

[0001] This invention relates to a method for treating ion exchange resins using micro-nano bubble water. Background Technology

[0002] Ultrapure water (UPW) preparation systems are crucial supporting systems for high-tech electronics industries such as integrated circuits. The quality of ultrapure water has a decisive impact on the yield of precision electronic components. Currently, the common requirement is that the total organic carbon (TOC) content of ultrapure water is below 5 ppb, or even 1 ppb. Therefore, to achieve the goal of removing trace amounts of TOC, not only is a complex ultrapure water preparation process required, but also the problem of contaminant leaching from equipment and materials in the ultrapure water preparation system must be solved.

[0003] Ultrapure water preparation systems require a large amount of ion exchange resin, such as the 2B3T unit in the front-end treatment system, the mixed-bed unit in the refining section, and the polishing mixed-bed unit. The water quality requirements for the front-end treatment system are not high, but in the refining and polishing process, the substances in the water reach the nanogram level, so it is crucial to minimize the leaching of TOC from the ion exchange resin. Since newly produced ion exchange resin contains residual organic solvents, organic additives, and unreacted monomers from the production process, it needs to undergo multiple cleaning stages before use to remove these residual organics. After cleaning, the ion exchange resin is rinsed with ultrapure water for a period of time. The TOC content in the rinsing solution is measured using an online TOC meter, and the difference between this and the actual TOC content of the ultrapure water is used to obtain ΔTOC. This method allows for the evaluation of the cleaning effect of resins treated by various methods. Currently, common cleaning processes involve acid-base pretreatment or methanol extraction. The acid-base pretreatment method is as follows: 1. Wash the resin repeatedly with hot water 7-8 times; 2. For cation exchange resin, wash it in sequence with 1 mol / L HCl, deionized water, NaCl solution, 1 mol / L NaOH, deionized water, 1 mol / L hydrochloric acid, and deionized water. For anion exchange resin, use the opposite acid-base washing sequence.

[0004] The above methods have obvious drawbacks: (1) Large amount of reagents: A large amount of acid and alkali is required to rinse the resin, resulting in high reagent costs. (2) Large amount of pure water: A large amount of deionized water is required to rinse the resin during cleaning, and residual reagents are rinsed between chemical washing intervals. (3) Cumbersome process: The water washing and chemical washing processes during cleaning are cumbersome and will generate a large amount of wastewater.

[0005] Besides the conventional methods mentioned above, existing technologies also utilize supercritical fluids to pretreat resins. For example, CN104475067A discloses the use of supercritical carbon dioxide to clean macroporous adsorption resins. This method requires spraying an entrainer composed of ethanol and ethyl acetate onto the resin. The resin mixed with the entrainer is then placed in an extraction vessel, and supercritical carbon dioxide is used to continuously circulate and extract the resin for 0.5 to 1 hour at 30–50°C and 10–20 MPa, thereby extracting residual organic matter from the resin pores. However, this method does not completely eliminate organic solvents (it still requires an entrainer), and the process is complex, difficult to scale up, and hard to achieve continuous production, resulting in poor overall economic efficiency. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a method for refining resins using carbon dioxide micro-nano bubble water instead of conventional acid and alkali agents. This method is simple and can significantly reduce the cost of agents and water.

[0007] Technical solution: The method for treating ion exchange resin using micro-nano bubble water purification according to the present invention includes the following steps: (1) Preparation of carbon dioxide functional water in gas-liquid mixing unit: Deionized water at a temperature of 15~20℃ and liquid carbon dioxide at a temperature of -20~20℃ and a pressure of 3.04~8.11MPa are respectively fed into the gas-liquid mixing unit through a booster pump. The gas-liquid mixing unit forms saturated carbon dioxide functional water under the conditions of a temperature of 10±2℃ and a pressure of 0.61~1.01MPa. (2) Preparation of micro-nano bubble water in micro-nano bubble generating unit (micro-nano bubble generator): The micro-nano bubble generating unit is composed of two-stage Venturi structures, wherein the cone angle of the Venturi structure diffusion tube section is 15~25°, and carbon dioxide functional water forms micro-nano bubble water with an average particle size of 0.08~1μm through the micro-nano bubble unit; (3) Micro-nano bubble water is injected from the bottom of the resin tank into the resin tank filled with ion exchange resin at a flow rate of 50~70 BV / h, and the cleaning volume is 100~300 BV to complete the cleaning of the ion exchange resin.

[0008] In step (1), the liquid carbon dioxide is required to have a purity greater than 99.99% and be stored in a pressurized liquid storage tank. The storage tank must be kept under high pressure, i.e., the temperature is maintained at -20℃ to 20℃ and the pressure is maintained at 3.04MPa to 8.11MPa.

[0009] The gas-liquid mixing unit is conical in shape with a top diameter of 300-500 mm. It includes a carbon dioxide inlet, a deionized water inlet, and an outlet at the bottom, which is connected to a micro / nano bubble generating unit. The carbon dioxide and deionized water inlets are arranged facing each other and tangentially along the cone. The inlet diameters of both the carbon dioxide and deionized water inlets are 50-100 mm. The gas-liquid mixing unit also includes a swirling guide plate. The distance H between the swirling guide plate and the inner wall is 2-2.5 times the diameter of the inlet. If the distance is less than 2 times, the axial flow in the mixing zone is obstructed; if the distance is greater than 2.5 times, the input liquid is too dispersed, and the swirling effect is impaired.

[0010] The height of the gas-liquid mixing unit is 1500~1700mm. To achieve a thorough and good mixing effect, so that liquid carbon dioxide can be converted into gas, the height of the gas-water mixing unit needs to reach 1500~1700mm. A negative pressure is formed at the center of the vortex, and the pressure reduction causes the liquid carbon dioxide to continuously vaporize and mix thoroughly with deionized water. The gas-water mixture, which is still in a vortex state, is then transported to the micro-nano bubble generating unit through the bottom outlet.

[0011] In step (3), the amount of ion exchange resin in the resin tank is 70-80% of the volume of the resin tank.

[0012] The micro-nano bubbles of this invention have a longer residence time in water compared to ordinary bubbles (millimeter-scale). After being generated in water, the bubbles rise to the surface and burst due to buoyancy. According to Stokes' law, the bubble's rising velocity is v = ρgd. 2 The buoyancy of micro- and nano-bubbles is proportional to the square of their diameter ( / 18μ), meaning their buoyancy is directly proportional to the square of the bubble diameter. Therefore, the buoyancy of micro- and nano-bubbles is significantly reduced compared to ordinary bubbles, allowing them to persist longer in liquid environments. Only with a sufficiently long residence time can these nano-bubbles reach the vicinity of the object's surface and collapse, thus exerting a cleaning effect at the closest distance. The surface zeta potential of micro- and nano-bubbles is negatively charged and hydrophobic, exhibiting excellent adsorption of residual organic matter within resins. Micro- and nano-bubbles can adsorb organic matter inside the resin's pores. Furthermore, the extremely high curvature of micro- and nano-bubbles results in significant surface tension, exceeding the internal air pressure and causing them to rupture. The immense force generated during rupture transforms water molecules, hydroxide ions, and other substances adsorbed in the surrounding environment of the micro-bubbles into free radicals. These highly oxidizing free radicals oxidize the organic matter, achieving a deep cleaning effect.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The method of the present invention uses micro-nano bubble water to replace cleaning agents (hydrochloric acid, liquid alkali) to finely treat ion exchange resin. While saving the amount of cleaning agents required, it can also reduce the acid and alkali wastewater caused by cleaning agents. At the same time, the cleaning water after gas-liquid separation does not need additional treatment and can be downgraded for use as cooling water; (2) The method of the present invention uses micro-nano bubbles to adsorb organic matter, and then removes organic residues on the surface and inside of the resin by the strong oxidizing free radicals generated by the bubble rupture, thereby effectively reducing the total organic carbon dissolved by the resin; (3) The method of the present invention directly uses liquid carbon dioxide and deionized water to mix, and generates a central negative pressure through swirling to make carbon dioxide complete phase change (from liquid phase to gas phase). During the phase change, the system loses heat and the temperature decreases. While increasing the solubility of carbon dioxide, it can also reduce the additional energy consumption required to create a low temperature and high pressure environment. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the method of the present invention; Figure 2 This is a top view of the gas-liquid mixing unit; Figure 3 This is a longitudinal cross-sectional view of the gas-liquid mixing unit and the micro / nano bubble generating unit; Figure 4 This is a schematic diagram of the principle of cleaning resin using micro-nano bubbles. Detailed Implementation

[0015] like Figures 1-3 As shown, in the method of the present invention, carbon dioxide functional water is generated through a gas-liquid mixing unit, and carbon dioxide functional water is transformed into carbon dioxide micro-nano bubble water through a micro-nano bubble generating unit. Finally, the carbon dioxide micro-nano bubble water is injected into a resin tank filled with ion exchange resin that needs to be treated.

[0016] The gas-liquid mixing unit is conical in shape with a top diameter of 300-500 mm. It includes a carbon dioxide inlet 1, a deionized water inlet 2, and an outlet 5 at the bottom, which is connected to the micro / nano bubble generating unit. The carbon dioxide inlet 1 and the deionized water inlet 2 are positioned opposite each other and tangentially along the cone. The inlet diameters of both inlets are 50-100 mm. The gas-liquid mixing unit also includes a swirling guide plate 3, with the distance H between the guide plate 3 and the inner wall being 2-2.5 times the inlet diameter. If the distance is less than 2 times, the axial flow in the mixing zone is obstructed; if it is greater than 2.5 times, the input liquid is too dispersed, resulting in impaired swirling effect. Impaired swirling effect leads to insufficient shear force and breaking capacity, causing the bubble size to increase. These large bubbles will quickly rise and burst, completely losing the characteristics of micro / nano bubbles.

[0017] To achieve a thorough and effective mixing effect, allowing liquid carbon dioxide to be converted into gas, the height of the gas-water mixing unit needs to reach 1500~1700mm. The vortex center 4 creates a negative pressure, and the reduced pressure causes the liquid carbon dioxide to continuously vaporize while being thoroughly mixed with deionized water. The gas-water mixture, still in a vortex state, is then transported to the micro-nano bubble generating unit through the bottom outlet.

[0018] The gas-liquid mixing unit must maintain a temperature of 10±2℃ and a pressure of 0.61~1.01MPa. Under these conditions, liquid carbon dioxide is converted into carbon dioxide gas during the swirling process. The volume of the liquid expands approximately 600~700 times during this gaseous transformation. To ensure sufficient gas dissolution to form a supersaturated state, the volume of input liquid carbon dioxide varies according to the pressure conditions (the higher the pressure, the greater the solubility of the gas in the liquid; the input volume of liquid carbon dioxide needs to vary according to the pressure conditions to ensure that the injected CO2 amount always matches the maximum dissolving capacity under the current pressure, thereby forming saturated carbon dioxide functional water), as shown in the table below:

[0019] The micro / nano bubble generating unit (micro / nano bubble generator) consists of a two-stage Venturi structure connected by a transition section 9. Each stage of the Venturi structure includes a constriction section 6, a throat section 7, and a diffuser section 8. The constriction section 6 of the first-stage Venturi structure is connected to the output port 5 of the gas-liquid mixing unit, and the diffuser section 8 of the second-stage Venturi structure is connected to the bottom of the resin tank through an L-shaped micro / nano bubble water output port 10. Carbon dioxide functional water forms a high-speed fluid after passing through the constriction-throat section, where locally generated turbulent vortices break up the bubbles. According to Bernoulli's formula, increased flow velocity reduces static pressure, and dissolved carbon dioxide gas forms bubbles through cavitation. The explosion during cavitation further breaks up the gas phase. The average particle size of the nano-microbubbles generated by the micro / nano bubble generator of this invention is 0.08~1μm. The micro / nano bubble water is fed into the bottom of the resin tank through the micro / nano bubble water output port 10. The resin tank is filled with ion exchange resin requiring further treatment, with a filling volume of 70~80%. Micro-nano bubble water is injected from the bottom of the resin tank, with the cleaning direction being bottom in and top out. The micro-nano bubble water is injected at a flow rate of 50~70 BV / h, and the cleaning volume can be 100~300 BV.

[0020] The cleaned micro-nano bubble water is collected from the top of the resin tank. The total organic carbon (TOC) dissolved from the resin is monitored online by a total organic carbon (TOC) analyzer. If the water quality is good, it can be downgraded for use, such as as cooling water.

[0021] During the cleaning process, a large number of micro- and nano-sized carbon dioxide bubbles enter the resin particles. Macroporous resins have pore sizes exceeding 100 nm, while gel-type resins have pore sizes around 2 nm. The negative charge on the bubble surface adsorbs similarly negatively charged organic contaminants. The movement of the bubbles carries away organic impurities from both the interior and surface of the resin particles. Simultaneously, the nucleation, separation, and collapse of the bubbles on the resin surface stimulate water molecules to form hydroxyl radicals, which simultaneously oxidize and mineralize the organic matter. This invention describes the micro- and nano-bubble resin cleaning process. Figure 4 As shown.

[0022] Example 1 based on Figures 1-3 A method for refining the cation exchange resin used in an ultrapure water preparation system using a device includes the following steps: (1) Liquid carbon dioxide at 10℃ and 5MPa is fed into the gas-liquid mixing unit at a flow rate of 26.325L / h, and deionized water at 15℃ and 0.61MPa is fed into the gas-liquid mixing unit at a flow rate of 2.5m³ / h. The gas-liquid mixing unit is at a temperature of 12.1℃ and a pressure of 0.61MPa to form saturated carbon dioxide functional water with a density of 6.75L / kg water. (2) Carbon dioxide functional water at a temperature of 12.0℃ and a pressure of 0.5Mpa is introduced into the micro-nano bubble generating unit, and the inclination angle of the Venturi diffuser section is 15° to form micro-nano bubble water with an average bubble size of about 0.1μm. (3) Use carbon dioxide micro-nano bubble water at a temperature of 12.0℃ and a pressure of 0.5Mpa to clean the ion exchange resin used in the polishing system at a flow rate of 50BV / h (the filling amount of ion exchange resin in the resin tank is 80% of the resin tank volume), the cleaning volume is 100BV, and the cleaning is completed.

[0023] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content of the ultrapure water was subtracted from the TOC content of the ultrapure water to obtain a leaching ΔTOC of approximately 0.8~0.9 ppb.

[0024] Comparative Example 1 The cation exchange resin in Example 1 was treated using Soxhlet extraction, including the following steps: (1) Rinse the resin to be treated with ultrapure water 3-4 times and soak it for 24 hours to swell. Then pack it into a Soxhlet extractor and add a methanol solution with a mass concentration greater than 95% into the extractor. The liquid level should be 10 cm higher than the resin layer height. Extract for 4 hours. (2) Filter the resin out of the extract and rinse the resin continuously with ultrapure water through the filter screen for 2 hours to wash away the methanol residue on the surface; (3) Pack the resin into the adsorption column (the amount of ion exchange resin is 80% of the volume of the adsorption column), rinse the resin with ultrapure water at a flow rate of 1 BV / hour, and rinse continuously for 10 hours to complete the cleaning.

[0025] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content was then subtracted from the value of the ultrapure water to obtain a leaching ΔTOC of approximately 1.8 ppb.

[0026] Comparative Example 2 The cation exchange resin in Example 1 is treated with acid and alkali solutions, including the following steps: (1) Rinse the resin with ultrapure water 3-4 times; (2) Use HCl and NaOH with a mass concentration of 4wt.% and twice the volume of the resin (abbreviated as 2BV) to alternately soak the resin in the adsorption column for 2 hours, and repeat twice; (3) Use ultrapure water to rinse between acid and alkali cleaning, until the pH of the effluent is 6-8, and the amount used each time is about 4 BV; (4) After completing two acid-base cycle cleanings, clean the resin with 4 wt.% HCl (4 BV) and soak for 2 hours. (5) Clean the resin with ultrapure water until the pH of the effluent is neutral. The cleaning is complete.

[0027] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content of the ultrapure water was subtracted from the TOC content of the ultrapure water, and the leaching ΔTOC was found to be approximately 1.9 ppb.

[0028] Comparative Example 3 - Compared with Example 1, the only difference is that the distance H between the swirl guide plate 3 and the inner wall in the gas-liquid mixing unit is 3.5 times the diameter of the inlet. A method for purifying a cation exchange resin used in an ultrapure water preparation system includes the following steps: (1) Liquid carbon dioxide at 10℃ and 5MPa is input into the gas-liquid mixing unit at a flow rate of 26.325L / h, and deionized water at 15℃ and 0.61MPa is input into the gas-liquid mixing unit at a flow rate of 2.5m³ / h. The distance H between the swirl guide plate 3 and the inner wall in the gas-liquid mixing unit is 3.5 times the diameter of the inlet. The gas-liquid mixing unit is at a temperature of 12.1℃ and a pressure of 0.61MPa, forming saturated carbon dioxide functional water with a density of 6.75L / kg water. (2) Carbon dioxide functional water enters the micro-nano bubble generating unit, and the inclination angle of the Venturi diffuser section is 15°, forming micro-nano bubble water with an average bubble size of about 0.25μm; (3) Clean the ion exchange resin used in the polishing system with carbon dioxide micro-nano bubble water at a flow rate of 50 BV / h (the filling amount of ion exchange resin in the resin tank is 80% of the resin tank volume), the cleaning volume is 100 BV, and the cleaning is completed.

[0029] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content of the ultrapure water was subtracted from the TOC content of the ultrapure water, and the soluble ΔTOC was found to be approximately 1.5 ppb.

[0030] Comparative Example 4 - The only difference from Example 1 is that the inclination angle of the Venturi diffuser section is 35°; A method for purifying a cation exchange resin used in an ultrapure water preparation system includes the following steps: (1) Liquid carbon dioxide at 10℃ and 5MPa is introduced into the gas-liquid mixing unit at a flow rate of 26.325L / h, and deionized water at 15℃ and 0.61MPa is introduced into the gas-liquid mixing unit at a flow rate of 2.5m³ / h. The gas-liquid mixing unit is at a temperature of 12.1℃ and a pressure of 0.61MPa, forming saturated carbon dioxide functional water with a density of 6.75L / kg water. (2) Carbon dioxide functional water enters the micro-nano bubble generating unit, and the inclination angle of the Venturi diffuser section is 35°, forming micro-nano bubble water with an average bubble size of about 0.2μm; (3) Clean the ion exchange resin used in the polishing system with carbon dioxide micro-nano bubble water at a flow rate of 50 BV / h (the filling amount of ion exchange resin in the resin tank is 80% of the resin tank volume), the cleaning volume is 100 BV, and the cleaning is completed.

[0031] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content of the ultrapure water was subtracted from the TOC content of the ultrapure water, and the soluble ΔTOC was found to be approximately 1.3 ppb.

[0032] Comparative Example 5 - The only difference from Example 1 is that carbon dioxide micro-nano bubble water was used to clean the ion exchange resin used in the polishing system at a flow rate of 30 BV / h. based on Figures 1-3 A method for refining the cation exchange resin used in an ultrapure water preparation system using a device includes the following steps: (1) Liquid carbon dioxide at 10℃ and 5MPa is introduced into the gas-liquid mixing unit at a flow rate of 26.325L / h, and deionized water at 15℃ and 0.61MPa is introduced into the gas-liquid mixing unit at a flow rate of 2.5m³ / h. The gas-liquid mixing unit is at a temperature of 12.1℃ and a pressure of 0.61MPa, forming saturated carbon dioxide functional water with a density of 6.75L / kg water. (2) Carbon dioxide functional water enters the micro-nano bubble generating unit, and the inclination angle of the diffusion tube section is 15°, forming micro-nano bubble water with an average bubble size of about 0.1μm; (3) Clean the ion exchange resin used in the polishing system with carbon dioxide micro-nano bubble water at a flow rate of 30 BV / h (the filling amount of ion exchange resin in the resin tank is 80% of the resin tank volume), the cleaning volume is 100 BV, and the cleaning is completed.

[0033] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content of the ultrapure water was subtracted from the TOC content of the ultrapure water, and the soluble ΔTOC was found to be approximately 1.1 ppb.

[0034] Comparative Example 6 - The only difference from Example 1 is that the micro / nano bubble generator is composed of a first-order Venturi structure; A method for purifying a cation exchange resin used in an ultrapure water preparation system includes the following steps: (1) Liquid carbon dioxide at 10℃ and 5MPa is introduced into the gas-liquid mixing unit at a flow rate of 26.325L / h, and deionized water at 15℃ and 0.61MPa is introduced into the gas-liquid mixing unit at a flow rate of 2.5m³ / h. The gas-liquid mixing unit is at a temperature of 12.1℃ and a pressure of 0.61MPa, forming saturated carbon dioxide functional water with a density of 6.75L / kg water. (2) Carbon dioxide functional water enters the micro-nano bubble generating unit. The micro-nano bubble generator is composed of a first-level Venturi structure. The inclination angle of the diffuser section is 15°, forming micro-nano bubble water with an average bubble size of about 0.4μm. (3) Clean the ion exchange resin used in the polishing system with carbon dioxide micro-nano bubble water at a flow rate of 50 BV / h (the filling amount of ion exchange resin in the resin tank is 80% of the resin tank volume), the cleaning volume is 100 BV, and the cleaning is completed.

[0035] The cleaned ion exchange resin was rinsed with ultrapure water for a period of time at a flow rate of 30 BV / h. After rinsing for one hour, the TOC content in the rinsing solution was detected using an online TOC meter. The TOC content was then subtracted from the value of the ultrapure water to obtain a leaching ΔTOC of approximately 1.6 ppb.

[0036] This invention utilizes micro-nano-sized carbon dioxide bubbles to efficiently clean impurities from the surface of resin particles through adsorption and oxidation, achieving a fine treatment effect (primarily used to reduce the leaching of organic impurities during the use of ion exchange resins). Compared to traditional cleaning processes that use acid and alkali washing to remove impurities remaining on the resin particle surface, which require rinsing with deionized water to remove residual cleaning solution during alternating processes, and especially in ultrapure water preparation systems where ultrapure water cleaning is even more necessary, this invention addresses the issue of high reagent costs, the use of large amounts of acids and alkalis increasing operating costs and generating significant waste liquid. Ultrapure water cleaning requires a large volume of water, almost 500 times the volume of the filled resin, further increasing operating costs. This invention uses micro-nano bubble water to replace conventional acid and alkali reagents for resin fine treatment, saving reagents. The principle is that micro-nano carbon dioxide bubbles penetrate deep into the microporous structure of the resin; the negative charge and oxidizing properties of the micro-nano bubble surface enhance the capture capacity of organic matter, thereby efficiently cleaning the resin. Simultaneously, the cavitation phenomenon formed by carbon dioxide gas on the surface of resin particles improves the hydraulic conditions during the cleaning process, strengthens the force at the solid-liquid interface on the organic matter attached to the resin surface, and enhances the cleaning effect. Furthermore, this invention eliminates the need for an additional ultrapure water rinsing process after cleaning, reducing water consumption. This invention mixes liquid carbon dioxide with water. Because the high-pressure deionized water cannot keep the carbon dioxide in a liquid state due to its temperature and pressure, a phase change occurs, resulting in gaseous carbon dioxide. During the phase change, the evaporation absorbs heat from the mixture, causing a temperature drop in the gas-liquid mixing unit; the expansion of carbon dioxide volume during the phase change increases the internal pressure of the system. Compared to traditional processes that require an additional booster pump to pressurize and dissolve the carbon dioxide gas, and a heat exchange unit to cool it and increase its solubility in water, this invention achieves pressurization and cooling directly through the phase change of the substance itself, effectively saving energy.

Claims

1. A method for treating ion exchange resin using micro / nano bubble water purification, characterized in that, Includes the following steps: (1) Preparation of carbon dioxide functional water in gas-liquid mixing unit: Deionized water at a temperature of 15~20℃ and 0.61~1.01MPa and liquid carbon dioxide at a temperature of -20~20℃ and 3.04~8.11MPa are respectively input into the gas-liquid mixing unit. The gas-liquid mixing unit forms saturated carbon dioxide functional water under the conditions of temperature of 10±2℃ and pressure of 0.61~1.01MPa. (2) Preparation of micro-nano bubble water in micro-nano bubble generating unit: The micro-nano bubble generating unit is composed of two-stage Venturi structures, wherein the cone angle of the Venturi structure diffusion tube section is 15~25°, and carbon dioxide functional water is formed into micro-nano bubble water through the micro-nano bubble unit; (3) Micro-nano bubble water is injected from the bottom of the resin tank into the resin tank filled with ion exchange resin at a flow rate of 50~70 BV / h, and the cleaning volume is 100~300 BV to complete the cleaning of the ion exchange resin.

2. The method according to claim 1, characterized in that: In step (1), the liquid carbon dioxide is required to have a purity greater than 99.99% and is stored in a pressurized liquid storage tank.

3. The method according to claim 1, characterized in that: In step (1), the gas-liquid mixing unit is conical in shape, with a diameter of 300~500mm in the top region.

4. The method according to claim 3, characterized in that: The gas-liquid mixing unit includes a carbon dioxide inlet, a deionized water inlet, and an outlet located at the bottom. The outlet is connected to the micro / nano bubble generating unit. The carbon dioxide inlet and the deionized water inlet are arranged facing each other and are both arranged along the tangential direction of a cone.

5. The method according to claim 4, characterized in that: The diameter of the inlet for both the carbon dioxide inlet and the deionized water inlet is 50-100 mm.

6. The method according to claim 4, characterized in that: The gas-liquid mixing unit is also equipped with a swirling guide plate, and the distance H between the swirling guide plate and the inner wall of the gas-liquid mixing unit is 2 to 2.5 times the diameter of the inlet.

7. The method according to claim 3, characterized in that: The height of the gas-liquid mixing unit is 1500~1700mm.

8. The method according to claim 1, characterized in that: In step (2), the two-stage Venturi structures are connected by a transition tube section. Each stage of the Venturi structure includes a contraction tube section, a throat section, and a diffusion tube section. The contraction tube section of the first-stage Venturi structure is connected to the output port of the gas-liquid mixing unit, and the diffusion tube section of the second-stage Venturi structure is connected to the bottom of the resin tank through an L-shaped micro-nano bubble water output port.

9. The method according to claim 1, characterized in that: In step (2), carbon dioxide functional water is formed by passing through micro-nano bubble units to form micro-nano bubble water with an average particle size of 0.08~1μm.

10. The method according to claim 1, characterized in that: In step (3), the amount of ion exchange resin in the resin tank is 70-80% of the volume of the resin tank.

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