Method for enhanced removal of taste and odor compounds from water using slow release organochlorine

Abstract

This invention provides a method for enhanced removal of odor substances from water using slow-release organochlorine, comprising the steps of adding slow-release organochlorine and potassium persulfate to water containing odor substances, and then subjecting the water to irradiation with ultraviolet light at a wavelength of 222 nm. This method significantly reduces the amount of persulfate used and achieves a remarkable deodorization effect.

Description

Technical Field

[0001] This invention belongs to the field of drinking water treatment technology, specifically relating to a method for enhanced removal of odor substances from water using slow-release organochlorine. Background Technology

[0002] 2-Methylisobcamol (2-MIB) is the most common odor compound in algae-containing water. Produced by a series of cyanobacteria, it produces a musty and earthy taste at nanogram levels per liter of water, leading to user concerns and complaints about water quality. The new version of the "Standards for Drinking Water Quality" (GB 5749-2022) stipulates a concentration limit of 10 ng / L for 2-MIB in treated water. 2-MIB has a low Henry's Law, strong antioxidant properties, and steric hindrance in its chemical structure, making it difficult for conventional drinking water treatment processes (coagulation, sedimentation, filtration, and disinfection) to effectively remove it. Furthermore, due to its relatively stable saturated cyclic tertiary alcohol structure, conventional oxidants (chlorine, chloramine, chlorine dioxide, potassium permanganate, etc.) have weak absorption in the ultraviolet (UV) wavelength range, and the degradation ability of commonly used UV irradiation (254 nm) for sterilization is also very limited. The problem of algae pollution in drinking water sources is difficult to solve.

[0003] In related technologies, the use of persulfate or monopersulfate can cause excessive sulfate levels in drinking water and lead to biological instability in water supply systems, posing a potential risk to water quality. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for the slow-release organochlorine-enhanced removal of odor substances from water, significantly reducing the use of persulfate and achieving a remarkable deodorization effect.

[0005] The first aspect of the present invention provides a method for enhanced removal of odor substances from water by slow-release organochlorine, comprising the steps of adding slow-release organochlorine and potassium persulfate to water containing odor substances and subjecting it to irradiation with ultraviolet light at a wavelength of 222 nm.

[0006] One technical solution of the present invention regarding a method for enhanced removal of odor substances from water using slow-release organochlorine has at least the following beneficial effects:

[0007] In related technologies, the specific wavelength for removing odor substances from water using ultraviolet light sources is unclear, and the characteristic wavelength for effective degradation of 2-MIB is not well defined. Furthermore, the dosage of oxidants such as persulfate or monopersulfate is large (100mol / L–1500mol / L, i.e., 16800g / L–252000g / L), resulting in extremely high reagent costs. This can also cause sulfate levels in water to exceed the limit (the limit in the National Standard for Drinking Water Quality GB5749-2022 is 250mg / L), leading to biological instability in drinking water supply systems and posing a potential risk to water quality. In addition, the pH range (3–8) is too broad, making it difficult to guide the selection of process parameters for actual odor substance removal.

[0008] The present invention provides a method for enhanced removal of odor substances from water using slow-release organochlorine, which solves the technical problem of high persulfate dosage in existing UV-activated persulfate (UV / PDS) systems. The proposed method uses a slow-release organochlorine-enhanced UV / PDS advanced oxidation system, which can significantly reduce the PDS dosage to 1–5 μmol / L, which is 1 / 2380–1 / 5940 times the lowest reported PDS dosage (2.38 mmol / L–29.7 mmol / L, CN109319879A).

[0009] The method for enhanced removal of odor substances from water using slow-release organochlorine provided by this invention exhibits a significant synergistic effect when the slow-release organochlorine is added to a UV / PDS system. The slow-release organochlorine is reacted with ultraviolet light and active free radicals (SO42-) in the UV / PDS system. -· and HO · The activation and generation of chlorine-containing free radicals enriched the variety of free radicals and increased their steady-state concentration, thereby improving the degradation rate of 2-MIB. The 2-MIB removal rate of UV / PDS (10 μM PDS) after 5 min of reaction was only 20%, and that of NaDCC alone (140 μM) after 5 min of reaction was only 5%. However, adding the above-mentioned dose of NaDCC (140 μM) to the UV / PDS (10 μM PDS) system resulted in a 2-MIB removal rate as high as 90.20% after 1 min of reaction.

[0010] The method for enhanced removal of odor substances in water by slow-release organochlorine provided by this invention is that the chlorine-containing free radicals generated in the slow-release organochlorine enhanced UV / PDS system are the core factor for improving the degradation of 2-MIB.

[0011] UV 222 The PDS system relies on the generation of ·OH and ·SO4. - The degradation of 2-MIB, in addition to the two types of free radicals mentioned above, also resulted in the formation of new chlorine-containing free radicals (·Cl, etc.) in the NaDCC-enhanced UV / PDS system. This invention demonstrates that ·Cl exhibits extremely high reactivity with 2-MIB, and that Cl...· The second-order reaction rate constant with 2-MIB is k. 2-MIB，·Cl =5.95×10 9 M -1 ·s -1 Its reactivity is comparable to that of hydroxyl radicals and 2-MIB (k 2-MIB，·OH =5.1×10 9 ), which is one order of magnitude higher than sulfate free radicals (k 2-MIB，·SO4 -=7.6±0.6×10 8 M -1 ·s -1 ).

[0012] 222nm wavelength ultraviolet light is harmless to the human body and can effectively and instantly disinfect aerosol viruses and bacteria. Because 222nm wavelength ultraviolet light cannot penetrate the stratum corneum of the skin and the tear film of the eye, it is extremely safe for the human body. At the same time, the energy of 222nm wavelength ultraviolet light can directly destroy the molecular chain structure of the DNA or RNA of bacteria and viruses, preventing pathogens from regenerating and achieving real-time and efficient disinfection in occupied environments.

[0013] According to some embodiments of the present invention, the odorant includes 2-methylisoborneol.

[0014] According to some embodiments of the present invention, the slow-release organochlorine comprises sodium dichloroisocyanurate.

[0015] According to some embodiments of the present invention, the dosage of the slow-release organochlorine is 10 mg / L to 40 mg / L.

[0016] According to some embodiments of the present invention, the molar ratio of the slow-release organochlorine and potassium persulfate is 7 to 150:1.

[0017] According to some embodiments of the present invention, the molar ratio of the slow-release organochlorine and potassium persulfate is 7 to 28:1.

[0018] According to some embodiments of the present invention, the molar ratio of the slow-release organochlorine and potassium persulfate is 7 to 14:1.

[0019] The method for enhanced removal of odor substances from water using slow-release organochlorine provided by this invention, in the NaDCC-enhanced UV / PDS system, has an optimal molar ratio of NaDCC to PDS ranging from 28:1 to 7:1. Under these conditions, the removal rate of 2-MIB reaches over 90% within 1 minute.

[0020] If the dosage ratio is lower than the optimal ratio, the NaDCC enhancement effect is insufficient, and the synergistic degradation effect of 2-MIB is not obvious.

[0021] If the dosage ratio is higher than the optimal ratio, the excess oxidant competes with 2-MIB for active free radicals, and a large number of free radicals are consumed by the oxidant, thus reducing the 2-MIB removal efficiency. When the molar ratio of NaDCC to PDS is 140:1, the degradation rate of 2-MIB decreases, but a 90% 2-MIB removal rate can still be achieved after 5 minutes of reaction.

[0022] According to some embodiments of the present invention, the irradiation reaction time is 1 min to 30 min.

[0023] According to some embodiments of the present invention, the ultraviolet light intensity of the irradiation reaction is 2–10 μW / cm². 2 .

[0024] According to some embodiments of the present invention, adding slow-release organic chlorine and potassium persulfate to water containing odor substances includes the following steps: first adding the potassium persulfate to the water, then irradiating it with 222nm wavelength ultraviolet light, and then adding the slow-release organic chlorine to the water.

[0025] First, potassium persulfate is added to the water and irradiated with 222nm wavelength ultraviolet light. Then, the slow-release organic chlorine is added to the water. This feeding method facilitates the full photolysis of potassium persulfate to generate more sulfate free radicals, thereby enhancing the process by which sulfate free radicals activate the slow-release organic chlorine to induce chlorine-containing free radicals and hydroxyl free radicals.

[0026] According to some embodiments of the present invention, the addition of slow-release organic chlorine and potassium persulfate to water containing odorous substances includes the following steps: simultaneously adding slow-release organic chlorine and potassium persulfate to water containing odorous substances, mixing well, and then irradiating the water with ultraviolet light at a wavelength of 222 nm.

[0027] Simultaneously, slow-release organic chlorine and potassium persulfate are added to the water containing odorous substances. This dosing method allows the two agents to be optimized in proportion to form an oxidizing solvent, which is suitable for water plant operators. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the reaction apparatus for implementing the method of the present invention.

[0029] Figure 2 This is a comparison chart of the effects of different processes on 2-MIB removal.

[0030] Figure 3 It is UV-free 222 The effect of NaDCC and PDS on 2-MIB removal under illumination.

[0031] Figure 4 NaDCC enhanced UV 222 / PDS and UV 222 / Comparison chart of the effect of PDS system in removing 2-MIB.

[0032] Figure 5 The molar ratio of NaDCC to PDS enhances UV radiation. 222 / Diagram of the effect of PDS removal of 2-MIB.

[0033] Figure 6 It is UV 222 Degradation mechanism diagram of 2-MIB by the / NaDCC / PDS process. Detailed Implementation

[0034] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0035] In some embodiments of the present invention, a method for enhanced removal of odor substances from water by slow-release organochlorine is provided, comprising the steps of adding slow-release organochlorine and potassium persulfate to water containing odor substances and subjecting it to irradiation with ultraviolet light at a wavelength of 222 nm.

[0036] In related technologies, the specific wavelength for removing odor substances from water using ultraviolet light sources is unclear, and the characteristic wavelength for effective degradation of 2-MIB is not well defined. Furthermore, the dosage of oxidants such as persulfate or monopersulfate is large (100mol / L–1500mol / L, i.e., 16800g / L–252000g / L), resulting in extremely high reagent costs. This can also cause sulfate levels in water to exceed the limit (the limit in the National Standard for Drinking Water Quality GB5749-2022 is 250mg / L), leading to biological instability in drinking water supply systems and posing a potential risk to water quality. In addition, the pH range (3–8) is too broad, making it difficult to guide the selection of process parameters for actual odor substance removal.

[0037] It should be noted that the method for enhanced removal of odor substances from water by slow-release organic chlorine provided by the present invention solves the technical problem of high persulfate dosage in existing ultraviolet-activated persulfate (UV / PDS) methods.

[0038] This invention proposes a slow-release organochlorine-enhanced UV / persulfate advanced oxidation system, which can significantly reduce the PDS dosage to 1–5 μmol / L, which is 1 / 2380 to 1 / 5940 times the lowest reported PDS dosage (2.38 mmol / L–29.7 mmol / L, CN109319879A). That is, the PDS dosage of this invention is only 2–20 μM, a reduction of 2380 to 5940 times.

[0039] It should also be noted that the method for enhanced removal of odor substances in water by slow-release organochlorine provided by the present invention exhibits a significant synergistic effect after the slow-release organochlorine is added to the UV / PDS system.

[0040] Slow-release organochlorine compounds in the UV / PDS system are reacted by ultraviolet light and active free radicals (SO4). -· and HO · It activates the generation of chlorine-containing free radicals, enriches the types of free radicals and increases the steady-state concentration of free radicals, thereby increasing the degradation rate of 2-MIB.

[0041] The UV / PDS system (PDS dosage of 10 μM) showed a 2-MIB removal rate of only 20% after 5 minutes of reaction, while NaDCC alone (140 μM) showed a 2-MIB removal rate of only 5% after 5 minutes of reaction. However, adding the above-mentioned dose of NaDCC (140 μM) to the UV / PDS system (PDS dosage of 10 μM) resulted in a 2-MIB removal rate as high as 90.20% after 1 minute of reaction, representing a 65% increase in 2-MIB removal rate.

[0042] Furthermore, the method for enhanced removal of odor substances from water using slow-release organochlorine provided by this invention utilizes chlorine-containing free radicals generated in the slow-release organochlorine-enhanced UV / PDS system as a core factor in improving 2-MIB degradation.

[0043] UV 222 The PDS system relies on the generation of ·OH and ·SO4. - The degradation of 2-MIB, and the formation of new chlorine-containing free radicals (·Cl, etc.) in the NaDCC-enhanced UV / PDS system in addition to the two types of free radicals mentioned above.

[0044] This invention demonstrates that Cl exhibits extremely high reactivity with 2-MIB. · The second-order reaction rate constant with 2-MIB is k. 2-MIB，·Cl =5.95×10 9 M -1 ·s -1 Its reactivity is comparable to that of hydroxyl radicals and 2-MIB (k 2-MIB，·OH =5.1×10 9 ), which is one order of magnitude higher than sulfate free radicals (k 2-MIB，·SO4 -=7.6±0.6×10 8 M -1 ·s -1 ).

[0045] In some embodiments of the present invention, the odorant includes 2-methylisoborneol.

[0046] In some embodiments of the present invention, the slow-release organochlorine includes sodium dichloroisocyanurate.

[0047] In some embodiments of the present invention, the dosage of slow-release organochlorine is 10 mg / L to 40 mg / L.

[0048] In some embodiments of the present invention, the molar ratio of slow-release organochlorine and potassium persulfate is 7 to 150:1.

[0049] In some embodiments of the present invention, the molar ratio of slow-release organochlorine and potassium persulfate is 7 to 28:1.

[0050] The method for enhanced removal of odor substances from water using slow-release organochlorine provided by this invention has an optimal molar ratio of NaDCC to PDS of 28:1 to 7:1 in the NaDCC-enhanced UV / PDS system.

[0051] Under these compounding conditions, the removal rate of 2-MIB reached over 90% within 1 minute.

[0052] If the dosage ratio is lower than the optimal ratio, the NaDCC enhancement effect is insufficient, and the synergistic degradation effect of 2-MIB is not obvious.

[0053] If the dosage ratio is higher than the optimal ratio, the excess oxidant will compete with 2-MIB for active free radicals, and a large number of free radicals will be consumed by the oxidant, thus reducing the removal efficiency of 2-MIB.

[0054] When the molar ratio of NaDCC to PDS is 140:1, the degradation rate of 2-MIB decreases, but a 2-MIB removal rate of 90% can still be achieved after 5 minutes of reaction.

[0055] In some embodiments of the present invention, the irradiation reaction time is 1 min to 30 min.

[0056] In some embodiments of the present invention, the ultraviolet light intensity of the irradiation reaction is 2–10 μW / cm². 2 .

[0057] In some embodiments of the present invention, the addition of slow-release organic chlorine and potassium persulfate to water containing odor substances includes the following steps: first, potassium persulfate is added to the water, then irradiated with 222nm wavelength ultraviolet light, and then slow-release organic chlorine is added to the water.

[0058] First, potassium persulfate is added to the water and then irradiated with 222nm wavelength ultraviolet light. Then, slow-release organic chlorine is added to the water. This feeding method facilitates the full photolysis of potassium persulfate to generate more sulfate free radicals, thereby enhancing the process by which sulfate free radicals activate slow-release organic chlorine to induce chlorine-containing free radicals and hydroxyl free radicals.

[0059] In some embodiments of the present invention, slow-release organic chlorine and potassium persulfate are added to water containing odorous substances, including the following steps: slow-release organic chlorine and potassium persulfate are added to water containing odorous substances at the same time, mixed well, and then irradiated with ultraviolet light at a wavelength of 222 nm.

[0060] Simultaneously, slow-release organic chlorine and potassium persulfate are added to the water containing odorous substances. This dosing method allows the two agents to be optimized in proportion to form an oxidizing solvent, which is suitable for water plant operators.

[0061] The technical solution of the present invention will be better understood below with reference to specific embodiments.

[0062] The relevant terms are explained below:

[0063] (1) UV 222 : Ultraviolet light with a characteristic wavelength of 222nm.

[0064] (2) PDS: Peroxysulphate. Potassium persulfate is used in this invention. Its CAS number is 7727-21-1 and its molecular weight is 270.322. It is a white crystalline powder that is soluble in water but insoluble in ethanol.

[0065] (3) UV 222 / PDS: First, PDS is added to the sample and mixed evenly. Then, the water sample is irradiated under ultraviolet light with a characteristic wavelength of 222nm, relying on the generation of active free radicals (hydroxyl radicals, sulfate radicals) to degrade pollutants.

[0066] (4) NaDCC: Sodium dichloroisocyanurate (CAS No. 2893-78-9) is a high-percentage solid chlorine chemical (55-63%). When dissolved in water, it produces cyanuric acid and a buffer solution composed of HClO and ClO-. Cyanuric acid is a stabilizer that prevents sunlight from consuming free chlorine. It features safe storage, long shelf life, high chlorine content, and continuous release effect.

[0067] (5) NaDCC enhanced UV 222 / PDS process: in UV 222 Add a certain concentration of NaDCC to the PDS system and mix thoroughly with a stirrer. Alternatively, add NaDCC and PDS to the water sample to be treated at a certain ratio and mix thoroughly, then place the water sample under a 222nm ultraviolet light wavelength for 0–30 min.

[0068] (6) 2-MIB: 2-Methylisoborneol, CAS No. 2371-42-8, molecular weight 168.28. It has an extremely low odor threshold (10 ng / L), a pungent odor, and is mostly secreted by algae such as Anabaena, which gives the water a fishy smell during algal blooms. It is the target pollutant of this invention.

[0069] The relevant testing methods are as follows:

[0070] 2-MIB Detection Method: SPME-GC-MS method was used for detection. GC-MS analysis conditions: gas chromatography column HP-5MS (30m×250μm×0.25μm), ion detection mode, sample inlet 250℃, ion source 230℃, initial temperature 60℃ held for 2 min, temperature increased to 100℃ at 15℃ / min, then increased to 250℃ at 8℃ / min and held for 2 min.

[0071] pH value: measured using a German Loebbon SD335 portable pH meter.

[0072] The method of this invention can be implemented in the following ways:

[0073] A certain volume of water sample contaminated with the odorant 2-MIB was placed in a beaker. Different concentrations of PDS were added to the water sample and stirred until homogeneous. The water sample was then irradiated under ultraviolet light with a characteristic wavelength of 222 nm. Within the next 1 minute, a certain concentration of NaDCC was added to the solution. The sample was then irradiated under ultraviolet light at a wavelength of 222 nm for 1–30 minutes, with a magnetic stirrer used continuously to ensure homogeneity.

[0074] Alternatively, add a certain ratio of NaDCC and PDS to the sample to be treated simultaneously, mix well, and then irradiate under ultraviolet light at a wavelength of 222nm for 1–30 min.

[0075] It should be noted that all reagents used in the examples were obtained from commercially available sources.

[0076] Example 1

[0077] Reaction apparatus such as Figure 1 As shown.

[0078] Parallel light was irradiated by a 222nm characteristic wavelength ultraviolet lamp, with an ultraviolet light intensity Is = 4.5μW / cm². 2 .

[0079] The reaction vessel is a 2L beaker.

[0080] The initial concentration of 2-MIB was 100 ng / L, the volume was 300 mL (water layer thickness < 3 cm), and the water sample was at room temperature of about 20℃ and pH = 6.5.

[0081] Since the two reagents are first mixed into an oxidizing solvent suitable for water plant operators, in order to simulate actual working conditions, [NaDCC] = 140 μM and [PDS] = 10 μM are added to the beaker at the same time, ultraviolet irradiation is turned on, and the magnetic stirrer is kept at 100 rpm to ensure that the solution is mixed evenly.

[0082] At 0, 5, 10, 15, 20, 25, and 30 min, 20 mL of sample solution was collected into 20 mL brown sample bottles. Excess Na2S2O3 solution was added to each sample to quench the excess oxidant, and 2-MIB was detected by SPME-GC-MS.

[0083] Comparative Example

[0084] Perform individual UV tests under the same conditions 222 NaDCC oxidation alone, PDS oxidation alone, UV 222 / NaDCC and UV 222 / PDS is used as a comparative example.

[0085] NaDCC enhances UV protection 222 Comparison of the effects of PDS system on 2-MIB removal

[0086] like Figure 2 As shown, NaDCC enhances UV 222 The PDS system can remove 90.2% of 2-MIB in 1 minute.

[0087] NaDCC enhances UV within 30 minutes of reaction. 222 The PDS process achieves a higher removal rate of 2-MIB than UV. 222 / PDS, UV 222 / NaDCC process.

[0088] Taking the 2-MIB removal rate at a reaction time of 5 min as an example for comparison: UV alone 222 The 2-MIB removal rate after irradiation was 3.3%, UV 222 / PDS (dosage 10μM) and UV 222 The removal rates of 2-MIB by NaDCC (dosage 140 μM) were 18.3% and 34.8%, respectively. NaDCC-enhanced UV... 222 The 2-MIB removal rate of the / PDS system was 90.2%, which was significantly greater than the cumulative value of the two processes (53.1%), indicating that the system exhibited a coupling effect.

[0089] like Figure 3 As shown, PDS and NaDCC, two oxidants, in the absence of UV radiation... 222The removal rates of 2-MIB in the irradiated dark system were only 4.1% and 3.1%, respectively, significantly lower than those of UV radiation. 222 / PDS, UV 222 The 2-MIB removal effect of the NaDCC process indicates the UV concentration in the reaction system. 222 Irradiation is an important factor in achieving efficient degradation of 2-MIB, and the active free radicals generated in the system make a significant contribution to the degradation of 2-MIB.

[0090] NaDCC enhances UV protection 222 / PDS system PDS dosage savings after removing 2-MIB

[0091] like Figure 4 As shown, the introduction of NaDCC significantly reduces UV radiation. 222 / The amount of PDS added in the PDS system.

[0092] Taking the 2-MIB removal rate at a reaction time of 5 min as an example for comparison: UV 222 In the PDS system, as the PDS dosage increased from 10 μM to 140 μM, the 2-MIB removal rate increased from 18.3% to 68.3%, an increase of 50%.

[0093] And using NaDCC to enhance UV 222 In the PDS system, a PDS dosage of only 10 μM is sufficient to achieve a more efficient 2-MIB removal rate (90.2%), compared to UV. 222 The removal rate of 2-MIB was further improved by 21.9% under the condition of 140 μM PDS, and the PDS dosage was reduced by 92.8%. Therefore, the use of NaDCC to enhance UV removal was effective. 222 / PDS process compared to UV 222 The PDS process has advantages in the degradation of 2-MIB.

[0094] NaDCC enhances UV protection 222 In the PDS system, the optimal ratio of NaDCC to PDS is...

[0095] Figure 5 The dosage ratio of NaDCC to PDS was further clarified.

[0096] UV 222 The degradation efficiency of 2-MIB was compared by adding different concentrations of PDS to NaDCC, and the results are as follows: Figure 5 As shown, when the molar ratio of NaDCC to PDS is in the range of 7:1 to 28:1, NaDCC enhances UV radiation. 222 / PDS achieved a removal rate of over 90% for 2-MIB within 1 minute.

[0097] When the NaDCC:PDS molar ratio is 140:1, the 2-MIB removal rate is 75% after 1 minute of reaction, and it can reach over 90% after 5 minutes. This indicates that the optimal NaDCC:PDS molar ratio is 28:1 to 7:1.

[0098] NaDCC enhances UV protection 222 / Reaction principle of 2-MIB removal in PDS system

[0099] Table 1 shows the second-order reaction rate constants of ·OH and ·SO4- with typical odor substances 2-MIB and geosmin GSM as reported in existing literature.

[0100] Table 1. Second-order reaction rate constants of free radicals with 2-MIB (unit: M) -1 ·s -1 )

[0101]

[0102] This invention utilizes laser flash photolysis technology to determine the second-order reaction rate constants of ·Cl with 2-MIB and GSM. From this data, it can be seen that the reactivity of ·OH and ·Cl with 2-MIB (10... 9 M -1 ·s -1 ) ratio of SO4- to 2-MIB reactivity (10 8 M -1 ·s -1 It is an order of magnitude higher.

[0103] like Figure 6 The left side, for UV 222 Regarding the degradation of 2-MIB in the / PDS system, UV 222 Photolysis of PDS initially generates ·SO4-, but only a small portion of ·SO4- is converted to ·OH, meaning the types and levels of free radicals in this reaction system are insufficient for the effective degradation of 2-MIB. Therefore, UV... 222 The amount of PDS required for PDS to degrade 2-MIB is high.

[0104] In comparison, such as Figure 6 On the right side, in NaDCC enhanced UV 222 In the PDS system, PDS first forms SO4- under 222nm ultraviolet irradiation. When NaDCC and PDS are added to the water sample in a molar ratio of 28:1 to 7:1, NaDCC is photolyzed by UV222 to generate some Cl- radicals. Another important pathway is that SO4- steals electrons from NaDCC, which promotes the large-scale generation of Cl-.

[0105] Cl· can directly degrade 2-MIB, and it can also be converted into ·OH in water, thus further degrading 2-MIB. Therefore, NaDCC enhances the generation of ·OH and ·Cl in the system, resulting in a significant reduction in PDS dosage and improved 2-MIB degradation efficiency.

[0106] If the molar ratio of NaDCC to PDS is higher than the range of 28:1 to 7:1, it means that there is not enough PDS in the system to be converted into SO4-, and it cannot participate in the activation process of NaDCC through electron transfer, thus reducing the removal efficiency of 2-MIB. On the other hand, if the molar ratio of NaDCC to PDS is lower than the range of 28:1 to 7:1, it means that excess PDS quenches the OH in the system, which is not conducive to the degradation of 2-MIB.

[0107] Example 2

[0108] The difference between this embodiment and Embodiment 1 is that [PDS] = 10 μM is first added to the water, and after irradiation with 222 nm wavelength ultraviolet light for 5 min, [NaDCC] = 140 μM is added to the water.

[0109] Test results showed that, at the same time point, the removal effect of 2-MIB was better than that of Example 1. This is because the feeding method facilitates the full photolysis of excess potassium sulfate to generate more sulfate free radicals, thereby enhancing the process of sulfate free radicals activating the slow-release organochlorine to induce chlorine-containing free radicals and hydroxyl free radicals.

[0110] As can be seen from the examples and comparative examples, the method for enhanced removal of odor substances in water by slow-release organic chlorine provided by the present invention solves the technical problem of high persulfate dosage in existing ultraviolet-activated persulfate (UV / PDS) methods.

[0111] This invention proposes a slow-release organochlorine-enhanced UV / persulfate advanced oxidation system, which can significantly reduce the PDS dosage to 1–5 μmol / L, which is 1 / 2380 to 1 / 5940 times the lowest reported PDS dosage (2.38 mmol / L–29.7 mmol / L, CN109319879A). That is, the PDS dosage of this invention is only 2–20 μM, a reduction of 2380 to 5940 times.

[0112] The method for enhanced removal of odor substances from water by slow-release organochlorine provided by this invention shows a significant synergistic effect when slow-release organochlorine is added to the UV / PDS system.

[0113] Slow-release organochlorine compounds in the UV / PDS system are reacted by ultraviolet light and active free radicals (SO4). -· and HO ·It activates the generation of chlorine-containing free radicals, enriches the types of free radicals and increases the steady-state concentration of free radicals, thereby increasing the degradation rate of 2-MIB.

[0114] The UV / PDS system (PDS dosage of 10 μM) showed a 2-MIB removal rate of only 20% after 5 minutes of reaction, while NaDCC alone (140 μM) showed a 2-MIB removal rate of only 5% after 5 minutes of reaction. However, adding the above-mentioned dose of NaDCC (140 μM) to the UV / PDS system (PDS dosage of 10 μM) resulted in a 2-MIB removal rate as high as 90.20% after 1 minute of reaction, representing a 65% increase in 2-MIB removal rate.

[0115] Furthermore, the method for enhanced removal of odor substances from water using slow-release organochlorine provided by this invention utilizes chlorine-containing free radicals generated in the slow-release organochlorine-enhanced UV / PDS system as a core factor in improving 2-MIB degradation.

[0116] UV 222 The PDS system relies on the generation of ·OH and ·SO4. - The degradation of 2-MIB, and the formation of new chlorine-containing free radicals (·Cl, etc.) in the NaDCC-enhanced UV / PDS system in addition to the two types of free radicals mentioned above.

[0117] This invention demonstrates that Cl exhibits extremely high reactivity with 2-MIB. · The second-order reaction rate constant with 2-MIB is k. 2-MIB，·Cl =5.95×10 9 M -1 ·s -1 Its reactivity is comparable to that of hydroxyl radicals and 2-MIB (k 2-MIB，·OH =5.1×10 9 ), which is one order of magnitude higher than sulfate free radicals (k 2-MIB，·SO4 -=7.6±0.6×10 8 M -1 ·s -1 ).

[0118] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for the slow-release organochlorine-enhanced removal of odor-causing substances 2-methylisoborneol from water, characterized in that, Includes the following steps: Potassium persulfate was first added to water containing odorous substances, and then irradiated with ultraviolet light at a wavelength of 222 nm. Slow-release organic chlorine was then added to the water for further irradiation. The slow-release organic chlorine was sodium dichloroisocyanurate. The molar ratio of the slow-release organochlorine and potassium persulfate is 7~28:

1.

2. The method according to claim 1, characterized in that, The dosage of the slow-release organochlorine is 10 mg / L to 40 mg / L.

3. The method according to claim 1, characterized in that, The irradiation reaction time is 1 min to 30 min.

4. The method according to claim 1, characterized in that, The ultraviolet light intensity of the irradiation reaction is 2~10 μW / cm. 2 .

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