Method for enhancing degradation of organic pollutants by ferrous ion-peracetic acid system

Abstract

The invention discloses a method for reinforcing a ferrous ion-peracetic acid system to degrade organic pollutants, and belongs to the field of environmental protection. The method comprises the following steps: adjusting the pH value of water to be treated to 3.0-5.0, and then adding ferrite, peracetic acid and a reducing agent; the reducing agent is sulfite or hydrosulfite. According to the method, Fe (III)-Fe (II) circulation is accelerated by using a reducing agent, and the organic pollutant degradation efficiency of the Fe (II) / peracetic acid system is improved by several times to dozens of times. Meanwhile, sulfite or hydrosulfite is converted into SO3, and SO3 is further converted into SO4 with strong oxidizing capacity in the presence of dissolved oxygen, so that the degradation rate of organic pollutants is increased. The peracetic acid can be effectively activated by adding a small amount of Fe (II), the amount of generated iron sludge is small, and the agent cost and the sludge treatment cost are effectively controlled.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection, and in particular relates to a method for strengthening a ferrous ion-peracetic acid system to degrade organic pollutants. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Water is an important natural resource, closely related to human production and life. However, with the large-scale discharge of industrial wastewater and domestic sewage, the large-scale use and loss of pesticides, fertilizers, and hormones, the water environment has been seriously polluted. With the improvement of environmental analysis technology, the types of trace organic pollutants detected in water have continued to increase, which has aroused people's attention to trace organic pollutants in the environment, especially some trace organic pollutants that are threatening and potentially threatening to the ecology and human body. Therefore, it is an arduous task for water treatment researchers to understand and master the migration and transformation laws of trace organic pollutants in the water treatment process, research and develop efficient, economical, and easy removal and control technologies, and ensure the safety of drinking water.

[0004] Conventional drinking water treatment processes (coagulation-sedimentation-filtration-disinfection) have little effect on removing most trace organic pollutants. In order to effectively remove organic pollutants in water and ensure the safety of drinking water, drinking water pretreatment or deep treatment processes are often added. Chemical oxidation is one of the effective methods for degrading organic matter in water. Chemical oxidation technology refers to the decomposition or transformation of pollutants in water through the oxidizing ability of the oxidant itself or active intermediates, thereby achieving the purpose of purifying water quality. In recent years, emerging advanced oxidation technologies based on peracetic acid have gradually attracted widespread attention from researchers in the industry due to their excellent disinfection performance, no carcinogenic and mutagenic byproducts during application, and a wide pH adaptability range. Among the peracetic acid activation technologies, transition metal ion activation technology has the advantages of simple operation, easy reaction control, and low application cost. Fe(II), as an activator that has been used for a long time in Fenton technology, has a stable effect, less pollution, and is low in price. It is very suitable for combining with peracetic acid to construct a new advanced oxidation system. For example, patent CN109231412A discloses a method for removing diclofenac from water by activating peracetic acid with ferrous ions, and Mo Yaojun et al. published "Degradation of sulfamethoxazole in water by ferrous ion-activated peracetic acid: dosing strategy and reaction mechanism", etc. It can be seen that the Fe(II) / peracetic acid system is widely used in the degradation of organic matter.

[0005] Fe(II) activates peracetic acid to produce free radicals such as HO•, CH3COO• and CH3COOO•, thereby achieving the oxidation of organic pollutants. At the same time, Fe(II) is converted into Fe(III) to form iron sludge. The effect of degrading organic pollutants is related to the Fe(II) dosage. Generally, an increase in the Fe(II) dosage helps to improve the pollutant degradation efficiency. However, an increase in the Fe(II) dosage causes a significant increase in the amount of iron sludge, resulting in an increase in disposal costs and an increase in the burden on enterprises. Therefore, how to achieve efficient degradation of organic pollutants by the Fe(II) / peracetic acid system at a lower Fe(II) dosage is the key to promoting the engineering application of this system. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method for strengthening the degradation of organic pollutants by a ferrous ion-peracetic acid system. The method provided by the present invention promotes the circulation of Fe(II) and Fe(III), thereby improving the pollutant degradation efficiency of the Fe(II) / peracetic acid system at a lower Fe(II) dosage.

[0007] In order to achieve the above object, the technical solution of the present invention is: The first aspect of the present invention provides a method for strengthening the degradation of organic pollutants by a ferrous ion-peracetic acid system, comprising: adjusting the pH of the water to be treated to 3.0-5.0, and then adding ferrous salt, peracetic acid and a reducing agent; The reducing agent reduces ferric ions to ferrous ions without consuming peracetic acid.

[0008] In some embodiments of the present invention, the ferrous salt includes at least one of ferrous chloride and ferrous sulfate.

[0009] In some embodiments of the present invention, the reducing agent is sulfite or bisulfite.

[0010] In some embodiments of the present invention, the reducing agent includes at least one of sodium sulfite, potassium sulfite, sodium bisulfite and potassium bisulfite.

[0011] In some embodiments of the present invention, the molar ratio of peracetic acid to ferrous salt is 20-1:1.

[0012] In some embodiments of the present invention, the molar ratio of the reducing agent to the ferrous salt is 50-5:1.

[0013] In some embodiments of the present invention, the method comprises: adjusting the pH of the water to be treated to 3.0-5.0 under stirring, first adding ferrous salt and peracetic acid, and then adding sulfite in batches.

[0014] In some embodiments of the present invention, sulfite is added in 3-5 portions.

[0015] In some embodiments of the present invention, the stirring speed is 30-300 rpm.

[0016] In some embodiments of the present invention, the water to be treated is at least one of surface water, groundwater, domestic sewage or industrial wastewater.

[0017] In some embodiments of the present invention, the organic pollutant includes at least one of phenol and bisphenol A.

[0018] The second aspect of the present invention provides a water treatment method, which comprises using the above method to remove organic pollutants in water.

[0019] The third aspect of the present invention provides the use of sulfite in accelerating iron circulation and enhancing the degradation of organic pollutants by peracetic acid.

[0020] The beneficial effects of the present invention are: The present invention discloses a method for strengthening the degradation of organic pollutants by a ferrous ion-peracetic acid system, which utilizes sulfite or bisulfite to accelerate the Fe(II)-Fe(III) cycle, thereby increasing the degradation efficiency of organic pollutants by the Fe(II) / peracetic acid system by several to dozens of times. Sulfite or bisulfite itself is converted into SO4 •− , SO4 •− It is a strong oxidant with high reactivity with most organic pollutants, and can further improve the efficiency of Fe(II) / sulfite / peracetic acid system in degrading organic pollutants. The Fe(II) used is converted into Fe(III) after the sulfite or bisulfite is consumed, which can be used as a coagulant to enhance the removal of pollutants. The present invention can effectively activate peracetic acid by adding a small amount of Fe(II), and the amount of iron sludge produced is small, so that the cost of reagents and sludge disposal can be effectively controlled.

[0021] The sulfite or bisulfite used in the present invention does not react with peracetic acid. By controlling the added amount of the sulfite or bisulfite, consumption of free radical precursors is avoided, thereby ensuring effective utilization of peracetic acid.

[0022] In the method provided by the present invention, the reagents used are Fe(II) salt, peracetic acid and bisulfite or sulfite. The reagents are cheap and the Fe(II) salt is used in small amounts. Therefore, the method has the advantage of low cost. Moreover, the amount of bisulfite or sulfite added is low, and the product after the reaction is sulfate, which does not affect water quality indicators under low dosage conditions. Moreover, the operation method provided by the present invention is simple, low in cost, and easy to scale up. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 This is a comparison diagram of the effects of Fe(II) (50 μmol / L) / peracetic acid (100 μmol / L) treating bisphenol A (a) in simulated water under the condition of pH=3.0 in Example 1 of the present invention and Fe(II) / peracetic acid treating bisphenol A (b) under the condition of sodium sulfite (400 μmol / L); Figure 2 This is a comparison diagram of the effects of treating bisphenol A (a) in simulated water with Fe(II) (50 μmol / L) / peracetic acid (100 μmol / L) at pH=3.0 in Example 2 of the present invention and treating bisphenol A (b) with Fe(II) / peracetic acid at pH=3.0 with sodium sulfite added in batches (100 μmol / L added at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively); Figure 3 This is a comparison diagram of the effects of treating bisphenol A (a) in simulated water with Fe(II) (50 μmol / L) / peracetic acid (100 μmol / L) at pH=3.0 in Example 3 of the present invention and treating bisphenol A (b) with Fe(II) / peracetic acid under the condition of adding sodium sulfite in batches (250 μmol / L at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively); Figure 4 This is a comparison diagram of the effects of treating bisphenol A (a) in simulated water with Fe(II) (50 μmol / L) / peracetic acid (200 μmol / L) at pH=3.0 in Example 4 of the present invention and treating bisphenol A (b) with Fe(II) / peracetic acid under the condition of adding sodium sulfite in batches (100 μmol / L at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively); Figure 5 This is a comparison diagram of the effects of treating bisphenol A (a) in simulated water with Fe(II) (50 μmol / L) / peracetic acid (200 μmol / L) at pH=3.0 in Example 5 of the present invention and treating bisphenol A (b) with Fe(II) / peracetic acid under the condition of adding sodium sulfite in batches (250 μmol / L at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively); Figure 6 This is a comparison diagram of the effects of Fe(II) (50 μmol / L) / peracetic acid (100 μmol / L) treating phenol in simulated water (a) at pH=3.0 in Example 6 of the present invention and Fe(II) / peracetic acid treating phenol (b) under the condition of adding sodium sulfite in batches (100 μmol / L at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively); Figure 7 This is a comparison chart of the effects of Fe(II) (50 μmol / L) / peracetic acid (100 μmol / L) on phenol in simulated water at pH = 3.0 in Example 6 of the present invention (a) and Fe(II) / peracetic acid on phenol (b) under the conditions of sequential addition of sodium sulfite (250 μmol / L at 3 minutes, 5 minutes, 10 minutes and 15 minutes, respectively). DETAILED DESCRIPTION

[0025] In view of the problem that the conversion of Fe(II) to Fe(III) fails when the existing Fe(II) / peracetic acid system degrades organic pollutants, resulting in a low pollutant degradation rate, the present invention provides a method for strengthening the degradation of organic pollutants by a ferrous ion-peracetic acid system. The method promotes the circulation of Fe(II) and Fe(III) by a reducing agent, thereby improving the pollutant degradation efficiency of the Fe(II) / peracetic acid system at a relatively low Fe(II) dosage.

[0026] A first typical embodiment of the present invention provides a method for enhancing the degradation of organic pollutants by a ferrous ion-peracetic acid system, comprising: adjusting the pH of the water to be treated to 3.0-5.0, and then adding ferrous salt, peracetic acid and a reducing agent; The reducing agent reduces ferric ions to ferrous ions without consuming peracetic acid.

[0027] The method provided by the present invention is to utilize a reducing agent to react with Fe(III) to reduce Fe(III) to Fe(II), and Fe(II) can continue to activate peracetic acid, thereby improving the degradation rate of organic pollutants while reducing the amount of ferrous salt. It can be seen that the present invention has developed a method for effectively improving the efficiency of pollutant degradation in the Fe(II) / peracetic acid system, the dosage of Fe(II) is small, Fe(II) can be circulated to participate in the reaction, the iron mud yield is small, and it has good application and market prospects.

[0028] It should be noted that, when adding ferrous salt and peracetic acid to the water to be treated, the ferrous salt and peracetic acid can be dissolved in distilled water to obtain a corresponding solution, and then added to the water to be treated. Alternatively, a pre-prepared ferrous salt stock solution (the solvent is distilled water) and peracetic acid stock solution (the solvent is distilled water) can be added to the water to be treated.

[0029] Furthermore, the pH of the water to be treated to which ferrous salt is added must be adjusted to 3.0-5.0 to ensure the form of ferrous ions.

[0030] In some examples of this embodiment, the ferrous salt is a ferrous salt that can activate peracetic acid, including but not limited to ferrous chloride, ferrous sulfate, and the like.

[0031] In some examples of this embodiment, the reducing agent is a reducing agent that can reduce ferric iron and does not consume peracetic acid, including but not limited to sulfite or bisulfite.

[0032] Sulfite reacts with Fe(III) to reduce Fe(III) to Fe(II), which can then activate peracetic acid. At the same time, sulfite is converted to SO3 •− , in the presence of dissolved oxygen, SO3 •− Further converted into SO4 with strong oxidizing ability •− , thereby improving the degradation rate of organic pollutants. The reagents are cheap and the amount of Fe(II) salt used is small. Therefore, this method has the advantage of low cost.

[0033] In some examples of this embodiment, the reducing agent includes but is not limited to at least one of sodium sulfite, potassium sulfite, sodium bisulfite and potassium bisulfite, preferably sodium sulfite.

[0034] In some examples of this embodiment, the molar ratio of peracetic acid to ferrous salt is 20-1:1, specifically 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1 and the like.

[0035] In some examples of this embodiment, the molar ratio of the reducing agent to the ferrous salt is 50-5:1, specifically 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, etc., preferably 40-5:1.

[0036] In some examples of this embodiment, the key to the method for strengthening the degradation of organic pollutants by the ferrous ion-peracetic acid system provided by the present invention is to control the method of adding sulfite. When excessive sulfite is added at one time, the sulfite consumes a large number of free radicals while reducing trivalent iron, which has an adverse effect on the degradation of pollutants and even produces an inhibitory effect. Therefore, the present invention proposes to add sulfite in batches. Under stirring, after adjusting the pH of the water to be treated to 3.0-5.0, first add ferrous salt and peracetic acid, and then add sulfite in batches; Preferably, the sulfite is added in 3-5 portions.

[0037] In some examples of this embodiment, the stirring speed is 100-300 rpm. The stirring can be performed using a reactor with a magnetic stirring device or a mechanical stirring device.

[0038] In some examples of this embodiment, the water to be treated is at least one of surface water, groundwater, domestic sewage or industrial wastewater.

[0039] In some examples of this embodiment, the organic pollutant includes but is not limited to at least one of phenol and bisphenol A.

[0040] The principle of the sulfite-enhanced Fe(II) / peracetic acid system for degrading organic pollutants in the present invention is that Fe(II) activates peracetic acid to produce free radicals, and itself is converted into Fe(III). Sulfite reduces Fe(III) to Fe(II), which accelerates the iron cycle, and the newly generated Fe(II) continues to activate peracetic acid to produce free radicals. In the present invention, Fe(II) circulates and participates in the reaction, and a small amount of Fe(II) can effectively activate peracetic acid. Therefore, the technology produces a small amount of iron sludge, which effectively controls the cost of reagents and sludge disposal. In addition, during the process of sulfite reducing Fe(III), it is oxidized to SO3 •− , in the presence of dissolved oxygen, SO3 •− Converted to SO4 •− , SO4 •− It is a strong oxidant that participates in the oxidation of pollutants and can further improve the efficiency of pollutant degradation in the Fe(II) / peracetic acid system.

[0041] Another typical embodiment of the present invention provides a water treatment method, which includes removing organic pollutants in water using the above method.

[0042] A third typical embodiment of the present invention provides the use of sulfite in accelerating iron circulation and enhancing the degradation of organic pollutants by peracetic acid.

[0043] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0044] In the following examples, the removal of organic matter from water was carried out in a reactor equipped with a mechanical stirring device at a stirring speed of 200 rpm, and the degradation degree of pollutants in water was evaluated by measuring the concentration change of pollutants in water.

[0045] Example 1 In the reactor, the simulated surface water containing 5 micromol / L bisphenol A was adjusted to pH 3.0, ferrous sulfate (final concentration 50 micromol / L) and peracetic acid (final concentration 100 micromol / L) were added to the simulated water, and then sodium bisulfite (final concentration 400 micromol / L) was added. After 30 minutes of reaction, the removal rate of bisphenol A was 66.9%.

[0046] Compared with comparative example 1, the removal rate of bisphenol A increased by 84% due to the addition of sodium bisulfite. Figure 1 .

[0047] Comparative Example 1 In the reactor, the simulated surface water containing 5 μmol / L bisphenol A was adjusted to pH 3.0, and then ferrous sulfate (final concentration 50 μmol / L) and peracetic acid (final concentration 100 μmol / L) were added to the simulated water. After 30 minutes of reaction, the removal rate of bisphenol A was 36.4%.

[0048] Example 2 The difference between this embodiment and embodiment 1 is that sodium bisulfite (final concentration 400 μmol / L) is evenly added in 4 times, at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively.

[0049] The removal rate of bisphenol A under this reaction condition is 132% higher than that of bisphenol A under the condition of no sodium bisulfite addition in Comparative Example 1. Figure 2 .

[0050] Example 3 The difference between this embodiment and embodiment 1 is that sodium bisulfite (final concentration 1000 μmol / L) is added evenly in 4 times, at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively. Under this reaction condition, the removal rate of bisphenol A after 30 minutes of reaction is 94.7%, which is 160% higher than the removal rate of bisphenol A under the condition of no sodium bisulfite addition in comparative example 1. For specific effect comparison data, see Figure 3 .

[0051] Embodiment 4: The present embodiment is different from the embodiment 1 in that the concentration of peracetic acid is increased to 200 μmol / L, and sodium bisulfite (final concentration 400 μmol / L) is evenly added in 4 times, at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively.

[0052] The removal rate of bisphenol A under this reaction condition is 99% higher than that of bisphenol A under the condition of no sodium bisulfite addition in Comparative Example 1. Figure 4 .

[0053] Example 5 The present embodiment is different from the embodiment 1 in that the concentration of peracetic acid is increased to 200 μmol / L, and sodium bisulfite (final concentration 1000 μmol / L) is evenly added in 4 times, at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively.

[0054] The removal rate of bisphenol A under this reaction condition is 237% higher than that of bisphenol A under the condition of no sodium bisulfite addition in Comparative Example 1. Figure 5 .

[0055] Example 6 The difference between this embodiment and embodiment 1 is that the pollutant is phenol with a concentration of 5 μmol / L, and sodium bisulfite (final concentration 400 μmol / L) is evenly added in 4 times, at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively.

[0056] The removal rate of phenol under this reaction condition is 444% higher than that of phenol under the condition of no sodium bisulfite addition in Comparative Example 2. Figure 6 .

[0057] Comparative Example 2 The difference between this comparative example and comparative example 1 is that the pollutant is phenol.

[0058] Example 7 The difference between this embodiment and embodiment 1 is that the pollutant is phenol with a concentration of 5 μmol / L, and sodium bisulfite (final concentration of 1000 μmol / L) is evenly added in 4 times, at 3 minutes, 5 minutes, 10 minutes and 15 minutes respectively.

[0059] The removal rate of phenol under this reaction condition is 639% higher than that of phenol under the condition of no sodium bisulfite addition in Comparative Example 2. Figure 7 .

[0060] From the above examples, it can be seen that the addition of sulfite in batches under the condition of 100-200 μmol / L peracetic acid can promote iron circulation, significantly improve the treatment effect of Fe(II) / peracetic acid system on wastewater containing organic pollutants such as bisphenol A and phenol, and effectively improve the degradation rate of pollutants. In particular, for phenol, the removal rate is significantly improved.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for strengthening the degradation of organic pollutants by a ferrous ion-peracetic acid system, characterized in that: include: Adjust the pH of the water to be treated to 3.0-5.0, and then add ferrous salt, peracetic acid and a reducing agent; The reducing agent reduces ferric ions to ferrous ions without consuming peracetic acid.

2. The method according to claim 1, characterized in that The ferrous salt includes at least one of ferrous chloride and ferrous sulfate; Preferably, the reducing agent is a sulfite or a bisulfite; further preferably, the reducing agent includes at least one of sodium sulfite, potassium sulfite, sodium bisulfite and potassium bisulfite.

3. The method according to claim 1, characterized in that The molar ratio of the peracetic acid to the ferrous salt is 20-1:

1.

4. The method according to claim 1, characterized in that The molar ratio of the reducing agent to the ferrous salt is 50-5:1, preferably 40-5:

1.

5. The method according to claim 1, characterized in that The method comprises: adjusting the pH of the water to be treated to 3.0-5.0 under stirring, first adding ferrous salt and peracetic acid, and then adding sulfite in batches; Preferably, the sulfite is added in 3-5 portions.

6. The method according to claim 5, characterized in that The stirring speed is 30-300 rpm.

7. The method according to claim 1, characterized in that The water to be treated is at least one of surface water, groundwater, domestic sewage or industrial wastewater.

8. The method according to claim 1, characterized in that The organic pollutant includes at least one of phenol and bisphenol A.

9. A water treatment method, characterized in that: The method comprises removing organic pollutants in water by using any method described in claims 1 to 8.

10. Application of sulfite in accelerating iron cycle and enhancing peracetic acid degradation of organic pollutants.

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