Method for disinfecting drinking water with solid hydrogen peroxide combined with ultrasound and ultraviolet light

Abstract

This invention belongs to the field of drinking water disinfection technology, specifically relating to a method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light. The method comprises two stages of disinfection: the first stage involves coating solid hydrogen peroxide and combining it with ultrasound; the water disinfected in the first stage then enters the second stage, where ultraviolet light is irradiated into the water to complete the disinfection. This invention uses sodium citrate and quaternary ammonium salts to coat the solid hydrogen peroxide, resulting in good stability and non-toxicity, making it suitable for drinking water disinfection without affecting the quality of the drinking water. The coating process is simple. The resulting coated solid hydrogen peroxide, combined with ultrasound and ultraviolet light, has a synergistic effect in disinfecting drinking water. Ultrasound and ultraviolet light enhance the disinfection effect of the coated solid hydrogen peroxide, resulting in a short disinfection time and a high sterilization rate. This disinfection method is simple, low-cost, and easy to operate, suitable for large-scale promotion and application, and has broad market prospects.

Description

Technical fields:

[0001] This invention belongs to the field of drinking water disinfection technology, specifically relating to a method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light. Background technology:

[0002] Hydrogen peroxide is a strong oxidizing agent. A certain concentration of hydrogen peroxide solution can kill microorganisms, including vegetative bacteria, spores, fungi, and viruses, leaving no residue and being non-toxic. It is commonly used for disinfection in water treatment plants. However, hydrogen peroxide is a hazardous chemical, making its transportation and use inconvenient.

[0003] Solid hydrogen peroxide, also known as sodium percarbonate, is a strong oxidizing agent with the chemical formula 2Na₂CO₃·3H₂O₂. It is a white crystalline powder that releases oxygen when exposed to moisture. Sodium percarbonate is an addition compound of hydrogen peroxide and sodium carbonate. It is mainly used as a bleaching agent and oxidizing agent, as well as a detergent, cleaning agent, and bactericide in chemical, papermaking, textile, dyeing and finishing, food, pharmaceutical, and sanitation industries. Because solid hydrogen peroxide is unstable, stabilizers are added during production, and encapsulating agents are added to the external stabilizers. Previously, coatings such as borates, perborates, phosphoric acid, or phosphates were effective, mainly used in washing and wastewater treatment. However, drinking water disinfection requires more stringent requirements for the coating components of the disinfectant. Currently, no coated solid hydrogen peroxide with good disinfection effect and simple process has been found. Research on methods for disinfecting drinking water with coated solid hydrogen peroxide is also limited, requiring further research and improvement to make drinking water disinfection methods simple, low-cost, and effective. Summary of the Invention:

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light. This method uses sodium citrate-coated solid hydrogen peroxide, combined with ultrasound and ultraviolet light, to disinfect drinking water, resulting in good disinfection effect and low chemical reagent consumption.

[0005] To achieve the above objectives, the present invention provides a method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light, the specific steps of which are as follows:

[0006] (1) Preparation of coated solid hydrogen peroxide: The coating material is a mixture of sodium citrate and quaternary ammonium cationic surfactant, with the following mass percentages: sodium citrate 55-75%, quaternary ammonium cationic surfactant 25-45%; anhydrous magnesium sulfate is selected as a desiccant and stabilizer; quaternary ammonium salt is selected as the surfactant, which can improve wet stability and thermal stability, has a low critical micelle concentration when dissolved, and has good emulsifying, foaming and foam-stabilizing properties, as well as good water solubility and salt resistance, which can more effectively reduce surface tension and has a significant synergistic effect on the bactericidal effect of solid hydrogen peroxide. The specific preparation method is as follows:

[0007] 1) Sodium citrate and quaternary ammonium salt cationic surfactant are mixed evenly to prepare a mixed solvent, which is the coating material;

[0008] 2) Preheat the fluidized bed to 40-45℃, and spray the prepared coating material onto the surface of solid hydrogen peroxide in the fluidized bed to obtain solid hydrogen peroxide with a primary coating.

[0009] 3) Continue to spray coating material onto the solid hydrogen peroxide that has already been coated once in the fluidized bed. The coating material for the two coatings accounts for 0.1-5% of the mass of the solid hydrogen peroxide. The particle size of the solid hydrogen peroxide after the two coatings is 1-3 mm.

[0010] 4) The solid hydrogen peroxide that has undergone two coating processes is fed into a fluidized bed dryer via a conveying system for drying. The drying temperature is controlled at 70-80℃, and the feed and discharge speeds of the dryer are also controlled to ensure the thickness of the material layer and a good fluidization state. After drying, it is mixed with anhydrous magnesium sulfate to obtain the finished coated solid hydrogen peroxide product. Then, it is packaged, inspected, and stored according to production requirements. The amount of anhydrous magnesium sulfate added is 1%-2% of the mass of the coated solid hydrogen peroxide.

[0011] (2) Disinfection: Water is disinfected using coated solid hydrogen peroxide in combination with ultrasound and ultraviolet light. The disinfection process is divided into two stages. The first stage is a combination of coated solid hydrogen peroxide and ultrasound. The mass-volume ratio of coated solid hydrogen peroxide to water is 3-6 mg: 1 L. The ultrasound frequency is 59 kHz and the power is 90 W. After the first stage of disinfection, the water enters the second stage of disinfection, which involves irradiating the water with ultraviolet light. The total disinfection time for the two stages is 5-10 min, which completes the disinfection of drinking water.

[0012] The specific process of the first stage of disinfection in this invention is as follows: an ultrasonic generator is installed in the first stage disinfection tank, water enters the disinfection tank from the inlet, and the coated solid hydrogen peroxide prepared in step (1) is added through the top opening of the disinfection tank. The first stage disinfection lasts for 4-8 minutes.

[0013] The specific process of the second stage disinfection in this invention is as follows: an ultraviolet generator is installed in the second stage disinfection tank, with an irradiation intensity of 70 μw / cm². 2 The second disinfection period is 1-2 minutes.

[0014] Compared with existing technologies, this invention uses sodium citrate and quaternary ammonium salts to coat solid hydrogen peroxide, resulting in good stability and non-toxicity, making it suitable for disinfecting drinking water without affecting its quality. The coating process is simple. The resulting coated solid hydrogen peroxide, combined with ultrasound and ultraviolet light, has a synergistic effect on the disinfection of drinking water. Ultrasound and ultraviolet light enhance the disinfection effect of the coated solid hydrogen peroxide, resulting in a short disinfection time and a high sterilization rate. This disinfection method is simple, low-cost, and easy to operate, making it suitable for large-scale promotion and application, with broad market prospects. Attached image description:

[0015] Figure 1 This is a schematic diagram illustrating the principle of the disinfection method involved in this invention. Detailed implementation method:

[0016] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] Example 1:

[0018] This embodiment relates to a method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light. The specific steps are as follows:

[0019] (1) Preparation of coated solid hydrogen peroxide: The coating material is a mixture of sodium citrate and quaternary ammonium cationic surfactant, with the following mass percentages: sodium citrate 55-75%, quaternary ammonium cationic surfactant 25-45%; sodium citrate is used as the coating material; anhydrous magnesium sulfate is selected as the desiccant and stabilizer; quaternary ammonium is selected as the surfactant, which can improve wet stability and thermal stability, has a low critical micelle concentration when dissolved, and has good emulsifying properties, foaming and foam stabilizing ability, as well as good water solubility and salt resistance, which can more effectively reduce surface tension and has a significant synergistic effect on the bactericidal effect of solid hydrogen peroxide; the specific preparation method is as follows:

[0020] 1) Sodium citrate and quaternary ammonium salt cationic surfactant are mixed evenly to prepare a mixed solvent, which is the coating material;

[0021] 2) Preheat the fluidized bed to 40-45℃, and spray the prepared coating material onto the surface of solid hydrogen peroxide in the fluidized bed to obtain solid hydrogen peroxide with a primary coating.

[0022] 3) Continue to spray coating material onto the solid hydrogen peroxide that has already undergone one coating in the fluidized bed. The coating material for the two coatings accounts for 0.1-5% of the mass of the solid hydrogen peroxide. The particle size of the solid hydrogen peroxide after the two coatings is 1-3 mm.

[0023] 4) The solid hydrogen peroxide that has undergone two coating processes is fed into a fluidized bed dryer via a conveying system for drying. The drying temperature is controlled at 70-80℃, and the feed and discharge speeds of the dryer are also controlled to ensure the thickness of the material layer and a good fluidization state. After drying, it is mixed with anhydrous magnesium sulfate to obtain the finished coated solid hydrogen peroxide product. Then, it is packaged, inspected, and stored according to production requirements. The amount of anhydrous magnesium sulfate added is 1%-2% of the mass of the coated solid hydrogen peroxide.

[0024] (2) First stage disinfection: Water is disinfected by using coated solid hydrogen peroxide in combination with ultrasound. Specifically, an ultrasound generator is set up in the first stage disinfection tank. Water enters the disinfection tank from the inlet. Coated solid hydrogen peroxide is added to the water. The mass-volume ratio of the amount of solid hydrogen peroxide added to the water is 3mg:1L. The applied ultrasound frequency is 59kHz and the ultrasound power is 90W. The water stays in the first stage disinfection tank for 4 minutes and then enters the second stage disinfection tank.

[0025] (3) Second stage disinfection: Ultraviolet light is used to disinfect water containing coated solid hydrogen peroxide. Specifically, the second stage disinfection tank is equipped with a UV reactor (ultraviolet reactor). The UVT (ultraviolet transmittance / penetration rate) of the influent is greater than 90%, the total power of the UV reactor is 90 kW, and the ultraviolet dose is 200-800 mJ / cm². 2 The water remains for 1 minute to complete the disinfection of drinking water.

[0026] The total disinfection time for the two stages in this embodiment is 5 minutes. The disinfection method described in this embodiment can handle a flow rate of 40,000 m³ / h. 3 / d of water is disinfected.

[0027] This embodiment tested drinking water before and after disinfection and found that the disinfection process had a good control effect on macromolecular components, represented by microbial degradation products and proteins, and also had a good removal effect on disinfection byproduct precursors such as DOC (soluble organic carbon), total organic matter UV254, 2-MIB (2-methylisoborneol), THMs (trihalomethanes), and HAAs. The results are shown in Table 1.

[0028] Table 1. Results of drinking water testing before and after disinfection

[0029] project DOC / (mg.L-') <![CDATA[UV254 / cm -1 ]]> 2-MIB / (ng.L') THMs precursors / (μg·L') HAAs precursors / (μg·L') Before disinfection 2.6～2.8 0.053～0.056 14～22 47.1～68.5 58.7～70.2 After disinfection 1.5～1.9 0.018～0.027 <5～10 22.7～41.2 31.5～37.4

[0030] Example 2:

[0031] This embodiment relates to a method for disinfecting drinking water using sodium percarbonate in combination with ultrasound and ultraviolet light. The difference from Embodiment 1 is that the mass-volume ratio of the added coated solid hydrogen peroxide to water is 6 mg: 1 L, and the total disinfection time is 5 min.

[0032] Example 3:

[0033] To verify the sterilization effect of the disinfection methods in Examples 1 and 2, this embodiment included five comparative examples, which differed from Example 1 in the following ways: Comparative Example 1: Disinfection of drinking water using only ultraviolet light; Comparative Example 2: Disinfection of drinking water using only coated solid hydrogen peroxide; Comparative Example 3: Disinfection of drinking water using only ultrasound; Comparative Example 4: Disinfection using a combination of coated solid hydrogen peroxide and ultraviolet light; Comparative Example 5: Disinfection of drinking water using both coated solid hydrogen peroxide and ultrasound. The levels of Escherichia coli and Staphylococcus aureus in the water before and after disinfection in Examples 1-2 and Comparative Examples 1-5 were measured, and the sterilization rate was calculated. The results are shown in Table 2.

[0034] Table 2 Results of bactericidal effect test

[0035]

[0036] Table 2 shows that ultrasound and ultraviolet light both have a synergistic effect on the sterilization of coated solid hydrogen peroxide, and the combined use of all three has the best disinfection effect. Ultraviolet irradiation can promote the decomposition of coated solid hydrogen peroxide to generate free radicals. These free radicals act on bacterial proteins and cortex, causing microorganisms to die rapidly.

[0037] Example 4:

[0038] This embodiment relates to the stability test of the coated solid hydrogen peroxide prepared in Example 1. Its active oxygen content, moisture content, pH value, thermal stability, wet stability, and total phosphorus content were tested using conventional methods in the art, with uncoated solid hydrogen peroxide as a comparison. The test results are shown in Table 3.

[0039] Table 3 Comparison of Detection Results

[0040]

[0041]

[0042] The experimental results in Table 3 clearly show that the stability of coated solid hydrogen peroxide is significantly higher than that of uncoated solid hydrogen peroxide, without affecting its content or other properties. This is because the coating material, composed of sodium citrate and quaternary ammonium cationic surfactant, forms a coating on the surface of the solid hydrogen peroxide particles. This coating improves the thermal and wet stability of the solid hydrogen peroxide; while uncoated sodium percarbonate has a strong hygroscopic effect, and its stability decreases significantly after absorbing water. By utilizing the hydrophilic and lipophilic properties of surfactants, the surface of solid hydrogen peroxide particles is modified, reducing their water absorption and improving the stability of sodium percarbonate.

Claims

1. A method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light, characterized in that, The disinfection process is divided into two stages. The first stage involves a combination of coated solid hydrogen peroxide and ultrasonic disinfection. After the first stage of disinfection, the water enters the second stage, which involves irradiating the water with ultraviolet light to complete the disinfection of the drinking water. The method described above is effective in removing soluble organic carbon, total organic matter, 2-methylisoborneol, trihalomethanes, and HAA disinfection byproduct precursors. The method for preparing the coated solid hydrogen peroxide is as follows: 1) Sodium citrate and quaternary ammonium salt cationic surfactant are mixed evenly to prepare a mixed solvent, which is the coating material; 2) Preheat the fluidized bed to 40-45℃, and spray the prepared coating material onto the surface of solid hydrogen peroxide in the fluidized bed to obtain solid hydrogen peroxide with a primary coating. 3) Continue spraying the coating material onto the solid hydrogen peroxide that has already undergone one coating in the fluidized bed; 4) The solid hydrogen peroxide that has undergone two coatings is fed into a fluidized bed dryer through a conveying system for drying. The drying temperature is controlled at 70-80℃, and the feed and discharge speeds of the dryer are controlled to ensure the thickness of the material layer and good fluidization. After drying, it is mixed with anhydrous magnesium sulfate to obtain coated solid hydrogen peroxide.

2. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that, The mass-volume ratio of the coated solid hydrogen peroxide to water is 3-6 mg: 1 L.

3. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that, The ultrasonic frequency is 59 kHz and the power is 90W.

4. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that, The intensity of ultraviolet radiation is 70 μW / cm 2 .

5. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that, The total disinfection time for the two stages of water disinfection is 5-10 minutes; the first stage disinfection takes 4-8 minutes, and the second stage disinfection takes 1-2 minutes.

6. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that, The coating material applied in the two coats accounts for 0.1-5% of the mass of solid hydrogen peroxide.

7. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 6, characterized in that, The amount of anhydrous magnesium sulfate added is 1%-2% of the mass of the coated solid hydrogen peroxide.

8. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 7, characterized in that, The mass percentage of sodium citrate and quaternary ammonium salt cationic surfactant is 55-75%: 25-45%.

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