A method for the ozone / permonosulfate homogeneous removal of taste and odor compounds from water

Abstract

The application discloses a method for removing odorants in water by using an ozone / potassium periodate homogeneous phase, which comprises adding ozone (O3) and potassium periodate (IO4 ‑ ) into water containing odorants; adjusting the pH value of the water to 6.0-8.0; and reacting for 3-10 minutes at 0-35 DEG C; wherein the molar ratio of O3 to IO4 ‑ is 1:2-10:1, the ozone dosage is 2.0-8.0 mg / L, and the potassium periodate dosage is 3.0-15.0 mg / L. The method can generate high-activity free radicals (·OH, IO3·, etc.) by using a homogeneous phase catalytic system, and thus realizes efficient degradation of the odorants.

Description

Technical Field

[0001] This invention belongs to the field of water treatment, specifically relating to a method for homogeneous ozone / periodate removal of odor substances from water. Background Technology

[0002] Odor and taste substances (such as 2-MIB, GSM, etc.) are typical recalcitrant pollutants in drinking water treatment. The "Standards for Drinking Water Quality" (GB5749-2022) has set a limit of no more than 10 ng / L for them. Existing water treatment processes (such as coagulation, sedimentation, filtration, conventional ozone oxidation, activated carbon adsorption, etc.) have low removal efficiency (usually less than 50%), which poses a challenge to the safety of drinking water. In recent years, advanced oxidation technologies (AOPs) have become a research hotspot due to their strong oxidizing capabilities. Systems such as UV / hydrogen peroxide and UV / persulfate can significantly improve the removal efficiency of odor substances in water. However, these technologies still face problems such as high energy consumption and insufficient UV efficiency (affected by organic matter in the water). Advanced oxidation technologies based on ozone have attracted widespread attention due to their ability to resist interference from organic matter. Technologies such as ozone / hydrogen peroxide and ozone / persulfate can significantly improve the removal capacity of odor substances. However, hydrogen peroxide is a precursor chemical and is not conducive to drug management. Persulfate treatment will significantly reduce the pH of the treated water. Novel ozone advanced oxidation technologies still need to be developed. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a method for the homogeneous and efficient removal of odor substances from water using ozone / periodate.

[0004] Technical solution: The method for homogeneous removal of odor substances from water by ozone / periodate according to the present invention includes the following steps: adding ozone (O3) and periodate (IO4-) to water containing odor substances; adjusting the pH of the water to 6.0-8.0; reacting at 0-35℃ for 3-10 minutes; wherein the molar ratio of O3 to IO4- is 1:2-10:1, the ozone dosage is 2.0-8.0 mg / L, and the periodate dosage is 3.0-15.0 mg / L.

[0005] Preferably, when the water temperature is 10–35℃ and the total dissolved solids (TDS) in the water is <1000 mg / L, the ozone dosage is 2.0–6.0 mg / L and the periodate dosage is 3.0–12.0 mg / L.

[0006] Preferably, when the water temperature is 0-10℃ and the total dissolved solids (TDS) in the water is <1000mg / L, the ozone dosage is 6.0-8.0mg / L, so that the removal rate of 2-MIB and GSM is >90%.

[0007] Preferably, when the total dissolved solids (TDS) in the water is ≥1000 mg / L, the periodate dosage is 12-15 mg / L, and the pH is controlled at 6.0-7.0, so that the removal rate of 2-MIB and GSM is >85%.

[0008] Preferably, the periodate is at least one of sodium periodate (NaIO4) and potassium periodate (KIO4).

[0009] More preferably, the periodate has a purity of >90% to ensure that the technology can efficiently generate hydroxyl radicals (·OH) and iodate radicals (IO3·) in the pH range of 6.0 to 8.0.

[0010] Preferably, the odorant includes at least one of 2-methylisoborneol (2-MIB) and geosmin (GSM).

[0011] Preferably, the initial concentration range of odor substances in the water is 30–300 ng / L.

[0012] Preferably, the ozone is directly introduced into the water body through an ozone generator, or dispersed in the form of microbubbles through a microporous diffuser, so as to improve ozone utilization and reduce exhaust emissions.

[0013] Preferably, continuous stirring or aeration is performed during the reaction process to enhance the mixing efficiency of ozone and periodate and the contact efficiency between free radicals and odor substances.

[0014] Preferably, the method is achieved by constructing multi-stage reaction zones:

[0015] (1) First-stage reaction zone: periodate addition and mixing zone;

[0016] (2) Second-stage reaction zone: Ozone is aerated through titanium plate aeration discs or microporous diffusers to achieve full gas-liquid mixing and enhance the generation of ·OH and IO3·.

[0017] (3) Third-stage reaction zone: Odor-causing substances in water are efficiently degraded to achieve the goal of deodorization.

[0018] The ozone / periodate homogeneous method for removing odor substances from water described in this invention is applicable to drinking water pretreatment or advanced treatment (such as lake and reservoir source water).

[0019] Reaction Principle: This technology achieves rapid free radical generation and efficient removal of odorous substances by controlling the ratio of oxidant and reaction conditions. The pathway for free radical generation in the ozone and periodate reaction system is as follows:

[0020] 2O3 + 2IO4 - +2H2O→2IO3·+4·OH+3O2.

[0021] Ozone molecules react directly with periodate ions to generate highly reactive iodate radicals (IO3·) and hydroxyl radicals (·OH). IO3· exhibits selective oxidizing ability against odor-causing substances, while ·OH achieves further degradation and mineralization of organic matter through non-selective attack. Odor-causing substances are efficiently degraded and deodorized by IO3· and ·OH through electron transfer and radical addition reactions, respectively.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] (1) The method of the present invention has a high efficiency in degrading odor substances in water: under the conditions of ozone dosage of 4.0 mg / L, periodate concentration of 6.0 mg / L and reaction time of 5 min, the removal rate of 2-MIB can reach 95.2%, the removal rate of GSM can reach 92.8%, and the removal rate of TOC can reach 25.7%, which is better than the control group of ozone oxidation alone (2-MIB removal rate of 46.5% and GSM removal rate of 46.7%) and periodate oxidation alone (2-MIB removal rate of 2.8% and GSM removal rate of 4.3%).

[0024] (2) The method of the present invention has broad applicability: when the water temperature is 0 to 10℃, the removal rate of 2-MIB and GSM can be increased to >90% by increasing the ozone dosage; when the total dissolved solids (TDS) of the water body is ≥1000mg / L, the periodate dosage can be adjusted and controlled to make the removal rate of 2-MIB and GSM >85%.

[0025] (3) The method of the present invention has safety assurance: ozone and periodate do not require additional energy input, can react at room temperature and pressure, are simple to operate, do not produce secondary pollution, and do not lead to the accumulation of by-products. Attached Figure Description

[0026] Figure 1 These are the electron paramagnetic resonance spectra of IO3· and ·OH identified in this invention (a. ·IO3; b. ·OH);

[0027] Figure 2 This is a result graph from Example 5 of the present invention (the effect of ozone / periodate treatment on a. 2-MIB and GSM, b. TOC, c. chloroform formation potential and dichloroacetic acid formation potential). Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Example 1:

[0030] The raw water from a reservoir in southern China was found to have a 2-MIB concentration of 164 ng / L, a GSM concentration of 22.4 ng / L, a total organic carbon (TOC) concentration of 3.7 mg / L, a pH of 7.2, a turbidity of 32 NTU, and a water temperature of 25℃. An ozone / sodium periodate advanced oxidation technology was used for treatment. First, 12.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 2.0 mg / L of ozone was added, with a molar ratio of ozone to sodium periodate of 1:0.75. Ozone was uniformly dispersed using a microporous diffuser. After 5 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 7.8 ng / L (removal rate of 95.2%), the GSM concentration decreased to 2.1 ng / L (removal rate of 90.6%), the TOC removal rate was 21.2%, and the residual total iodate was 0.08 mg / L. Comparative experiments with conventional ozone oxidation (ozone dosage of 2.0 mg / L) and periodate oxidation (dosage of 12.0 mg / L) showed that ozone treatment alone could remove only 38.6% of 2-MIB and 28.8% of GSM, while periodate oxidation alone could remove only 8.6% of 2-MIB and 6.7% of GSM.

[0031] Example 2:

[0032] The raw water from a southern lake was found to contain 223.7 ng / L of 2-MIB, 28.6 ng / L of GSM, 4.5 mg / L of total organic carbon (TOC), with a pH of 7.7, a turbidity of 45 NTU, and a water temperature of 22℃. An ozone / potassium periodate advanced oxidation technology was used for treatment. First, 3.0 mg / L of potassium periodate was added and mixed thoroughly. Then, 6.0 mg / L of ozone was added, and aeration using titanium plates was used to ensure uniform ozone dispersion. The molar ratio of ozone to sodium periodate was 9.6:1. After 10 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 5.3 ng / L (removal rate of 97.6%), the GSM concentration decreased to 2.7 ng / L (removal rate of 90.6%), and the TOC removal rate was 26.4%. Comparative experiments with conventional ozone oxidation (ozone dosage of 6.0 mg / L) and periodate oxidation (dosage of 3.0 mg / L) showed that ozone treatment alone could remove only 67.4% of 2-MIB and 56.3% of GSM, while periodate oxidation alone could remove only 2.4% of 2-MIB and 5.4% of GSM.

[0033] Example 3:

[0034] The effluent from the sedimentation tank of a typical water plant in southern China, which uses lake water as its source, showed a 2-MIB concentration of 36.4 ng / L, a GSM concentration of 14.7 ng / L, a total organic carbon (TOC) concentration of 2.8 mg / L, a pH of 7.7, a turbidity of 2.3 NTU, and a water temperature of 19℃. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 6.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 4.0 mg / L of ozone was added, and uniform ozone dispersion was achieved through titanium plate aeration. The molar ratio of ozone to sodium periodate was 2.96:1. After 5 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 2.2 ng / L (removal rate of 94.0%), the GSM concentration decreased to 1.1 ng / L (removal rate of 92.5%), and the TOC removal rate was 19.4%. Comparative experiments with traditional ozone oxidation (ozone dosage of 4.0 mg / L) and periodate oxidation (dosage of 6.0 mg / L) showed that ozone treatment alone could remove only 43.5% of 2-MIB and 41.7% of GSM, while periodate oxidation alone could remove only 3.5% of 2-MIB and 4.9% of GSM. After chlorination disinfection (sodium hypochlorite dosage of 1.0 mg / L), the concentrations of chloroform and dichloroacetic acid generated from the treated water were 13.4 μg / L and 7.8 μg / L, respectively, significantly lower than the concentrations of chloroform and dichloroacetic acid generated from untreated water after chlorination disinfection (20.5 μg / L and 12.1 μg / L, respectively).

[0035] Example 4:

[0036] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water. The pH was adjusted to 8.0 using sulfuric acid and sodium hydroxide, and the water temperature was controlled at 10℃. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 9.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 4.0 mg / L of ozone was added, with a molar ratio of ozone to sodium periodate of 1.98:1. Ozone was uniformly dispersed using a microporous diffuser. After 3 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 5.3 ng / L, with a removal rate as high as 94.7%, and the GSM concentration decreased to 6.6 ng / L, with a removal rate as high as 93.4%. Comparative experiments with conventional ozone oxidation (ozone dosage of 4.0 mg / L) and periodate oxidation (dosage of 9.0 mg / L) showed that ozone treatment alone could remove only 41.1% of 2-MIB and 34.6% of GSM, while periodate oxidation alone could remove only 3.4% of 2-MIB and 4.0% of GSM.

[0037] Example 5:

[0038] (1) First, add 6.0 mg / L of sodium periodate to pure water, mix well, and then add 4.0 mg / L of ozone. The ozone is uniformly dispersed using a microporous diffuser. The molar ratio of ozone to sodium periodate is 2.96:1. Add 1 mmol / L of 5,5-dimethyl-1-pyrrolidone-N-oxide as ·PO4. 2- The scavenging agent was used, and the free radicals were immediately determined using electron paramagnetic resonance spectroscopy. For example... Figure 1 Electron paramagnetic resonance spectroscopy detected characteristic peaks of ·OH and IO3·, confirming the generation of ·OH and IO3·.

[0039] (2) A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water at a pH of 7.1 and a temperature of 22℃. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 6.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 4.0 mg / L of ozone was added, and the ozone was evenly dispersed using a microporous diffuser. The molar ratio of ozone to sodium periodate was 2.96:1. Water quality analysis after 5 minutes of treatment showed that the 2-MIB concentration decreased to 4.8 ng / L (removal rate as high as 95.2%), the GSM concentration decreased to 7.2 ng / L (removal rate as high as 92.8%), and the TOC removal rate was 25.7%. Comparative experiments with traditional ozone oxidation (ozone dosage 4.0 mg / L) and periodate oxidation (dosage 6.0 mg / L) showed that ozone treatment alone could remove only 46.5% of 2-MIB and 46.7% of GSM, while periodate oxidation alone could remove only 2.8% of 2-MIB and 4.3% of GSM. After chlorination disinfection (sodium hypochlorite dosage 1.0 mg / L), the concentrations of chloroform and dichloroacetic acid generated from the treated water were 4.5 μg / L and 3.3 μg / L, respectively, lower than the concentrations of chloroform and dichloroacetic acid generated from untreated water after chlorination disinfection (5.7 μg / L and 6.1 μg / L, respectively). The results are as follows... Figure 2 As shown.

[0040] Example 6:

[0041] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water at a pH of 6.0 and a temperature of 35°C. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 10.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 2.0 mg / L of ozone was added, and the ozone was evenly dispersed using a microporous diffuser. The molar ratio of ozone to sodium periodate was 0.89:1. After 5 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 3.3 ng / L, with a removal rate as high as 96.7%, and the GSM concentration decreased to 6.1 ng / L, with a removal rate as high as 93.9%. Comparative experiments with conventional ozone oxidation (ozone dosage of 2.0 mg / L) and periodate oxidation (dosage of 10.0 mg / L) showed that ozone treatment alone could remove only 29.4% of 2-MIB and 25.6% of GSM, while periodate oxidation alone could remove only 2.7% of 2-MIB and 3.5% of GSM.

[0042] Example 7:

[0043] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water, with a pH of 7.1, simulating low winter conditions and a controlled water temperature of 5°C. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 6.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 8.0 mg / L of ozone was added, and uniform ozone dispersion was achieved through titanium plate aeration. The molar ratio of ozone to sodium periodate was 5.95:1. Water quality analysis after 5 minutes of treatment showed that the 2-MIB concentration decreased to 9.1 ng / L, with a removal rate of 90.9%, and the GSM concentration decreased to 9.7 ng / L, with a removal rate of 90.3%. Comparative experiments with conventional ozone oxidation (ozone dosage of 8.0 mg / L) and periodate oxidation (dosage of 6.0 mg / L) showed that ozone treatment alone could remove only 42.1% of 2-MIB and 35.4% of GSM, while periodate oxidation alone could remove only 2.6% of 2-MIB and 4.8% of GSM.

[0044] Example 8:

[0045] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water, with a pH of 7.0, simulating low winter conditions and a controlled water temperature of 10℃. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 6.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 6.0 mg / L of ozone was added, with uniform ozone dispersion achieved through titanium plate aeration. The molar ratio of ozone to sodium periodate was 4.46:1. Water quality analysis after 5 minutes of treatment showed that the 2-MIB concentration decreased to 8.2 ng / L, with a removal rate as high as 91.8%, and the GSM concentration decreased to 6.7 ng / L, with a removal rate as high as 93.3%. Comparative experiments with conventional ozone oxidation (ozone dosage of 6.0 mg / L) and periodate oxidation (dosage of 6.0 mg / L) showed that ozone treatment alone could remove only 40.5% of 2-MIB and 29.6% of GSM, while periodate oxidation alone could remove only 2.4% of 2-MIB and 4.2% of GSM.

[0046] Example 9:

[0047] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water, with a pH of 7.0, simulating low winter conditions and a controlled water temperature of 0°C. Ozone / sodium periodate advanced oxidation technology was used for treatment. First, 6.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 7.0 mg / L of ozone was added, and aeration using titanium plates was used to ensure uniform ozone dispersion. The molar ratio of ozone to sodium periodate was 5.20:1. After 5 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 9.8 ng / L, with a removal rate of 90.2%, and the GSM concentration decreased to 8.9 ng / L, with a removal rate of 91.1%. Comparative experiments with conventional ozone oxidation (ozone dosage of 7.0 mg / L) and periodate oxidation (dosage of 6.0 mg / L) showed that ozone treatment alone could remove only 33.4% of 2-MIB and 36.5% of GSM, while periodate oxidation alone could remove only 2.7% of 2-MIB and 3.6% of GSM.

[0048] Example 10:

[0049] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water, the pH was adjusted to 7.0, and the water temperature was 22℃. Additional dissolved solids were added, bringing the initial dissolved solids concentration to 1225 mg / L. Treatment was performed using ozone / sodium periodate advanced oxidation technology. First, 14.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 4.0 mg / L of ozone was added, and aeration using titanium plates was used to ensure uniform ozone dispersion. The molar ratio of ozone to sodium periodate was 1.28:1. After 10 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 12.4 ng / L, with a removal rate of 87.6%, and the GSM concentration decreased to 11.2 ng / L, with a removal rate of 88.8%. Comparative experiments with conventional ozone oxidation (ozone dosage of 4.0 mg / L) and periodate oxidation (dosage of 14.0 mg / L) showed that ozone treatment alone could remove only 38.3% of 2-MIB and 35.4% of GSM, while periodate oxidation alone could remove only 6.7% of 2-MIB and 8.4% of GSM.

[0050] Example 11:

[0051] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water, the pH was adjusted to 6.0, and the water temperature was 22℃. Additional dissolved solids were added, bringing the initial dissolved solids concentration to 1225 mg / L. Treatment was performed using ozone / sodium periodate advanced oxidation technology. First, 15.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 4.0 mg / L of ozone was added, and aeration using titanium plates was used to ensure uniform ozone dispersion. The molar ratio of ozone to sodium periodate was 1.19:1. After 10 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 9.2 ng / L, with a removal rate of 90.8%, and the GSM concentration decreased to 8.3 ng / L, with a removal rate of 91.7%.

[0052] Example 12:

[0053] A small-scale laboratory water treatment experiment was conducted. 100 ng / L of 2-MIB and GSM were added to pure water, the pH was adjusted to 6.5, and the water temperature was 22℃. Additional dissolved solids were added, bringing the initial dissolved solids concentration to 1225 mg / L. Treatment was performed using ozone / sodium periodate advanced oxidation technology. First, 12.0 mg / L of sodium periodate was added and mixed thoroughly. Then, 4.0 mg / L of ozone was added, and aeration using titanium plates was used to ensure uniform ozone dispersion. The molar ratio of ozone to sodium periodate was 1.49:1. After 10 minutes of treatment, water quality analysis showed that the 2-MIB concentration decreased to 13.9 ng / L, with a removal rate of 86.1%, and the GSM concentration decreased to 14.2 ng / L, with a removal rate of 85.8%.

Claims

1. A method for homogeneous ozone / periodate removal of odor substances from water, characterized in that, Includes the following steps: Adding ozone (O3) and periodate (including IO4) to water bodies containing odorous substances. - Adjust the pH of the water to 6.0-8.0; react for 3-10 minutes at 0-35℃; O3 and IO4 are involved. - The molar ratio is 1:2 to 10:1, the ozone dosage is 2.0 to 8.0 mg / L, and the periodate dosage is 3.0 to 15.0 mg / L.

2. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, When the water temperature is 10 ~ 35 ℃ and the total dissolved solids (TDS) in the water body is < 1000 mg / L, the ozone dosage is 2.0 ~ 6.0 mg / L and the periodate dosage is 3.0 ~ 12.0 mg / L.

3. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, When the water temperature is 0 ~ 10℃ and the total dissolved solids (TDS) in the water body is < 1000 mg / L, the ozone dosage is 6.0 ~ 8.0 mg / L.

4. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, When the total dissolved solids (TDS) in the water body is ≥1000 mg / L, the dosage of periodate should be 12 ~ 15 mg / L, and the pH should be controlled at 6.0 ~ 7.

0.

5. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, The periodate is at least one of sodium periodate (NaIO4) and potassium periodate (KIO4).

6. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, The odorant includes at least one of 2-methylisoborneol (2-MIB) and geosmin (GSM).

7. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, The initial concentration range of odor substances in the water is 30 ~ 300 ng / L.

8. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, The ozone is introduced directly into the water body through an ozone generator, or dispersed in the form of microbubbles through a microporous diffuser.

9. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, During the reaction, continuous stirring or aeration is performed.

10. The method for homogeneous ozone / periodate removal of odor substances from water according to claim 1, characterized in that, The method is achieved by constructing multi-stage reaction zones: (1) First-stage reaction zone: periodate addition and mixing zone; (2) Second-stage reaction zone: Ozone is aerated through titanium plate aeration discs or microporous diffusers to achieve full gas-liquid mixing and enhance the generation of ·OH and IO3·. (3) Third-stage reaction zone: Odor-causing substances in water are efficiently degraded to achieve the goal of deodorization.

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