Method for microbubble-assisted oxidative degradation of iron-based catalyst

Abstract

The invention provides a microbubble-assisted iron-based catalyst oxidative degradation method, which comprises the following steps: pretreating a water body, introducing an iron-based catalyst, introducing microbubbles into the water body, and carrying out oxidative degradation. The micro-bubbles enrich a large amount of hydroxyl ions by using a huge gas-liquid interface potential difference, and provide a continuous electron donor environment for the iron-based catalyst, so that a non-traditional Fenton-like reaction is initiated and maintained, and hydroxyl radicals are efficiently and continuously generated under acidic or neutral conditions without adding hydrogen peroxide. The method overcomes the dependence of the traditional Fenton technology on a strong acid environment and a large amount of hydrogen peroxide, is low in operation cost, is environment-friendly, and is suitable for treating degradation-resistant organic wastewater, low-valence metal ion wastewater and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of advanced oxidation technology, and in particular to a method for micro-bubble assisted iron-based catalyst oxidation degradation. BACKGROUND

[0002] Fenton method in advanced oxidation technology is widely used in the treatment of refractory organic wastewater because it can produce strong oxidizing hydroxyl radicals. However, this technology has two significant bottlenecks: first, the reaction must be carried out under strong acidic conditions, which leads to high acid-base adjustment costs and operational complexity; second, it requires continuous addition of hydrogen peroxide as a reactant, which not only has high operating costs, but also has safety hazards in storage and transportation.

[0003] In order to overcome these defects, CN120553856A discloses an advanced oxidation system of ozone activated sulfite, which can efficiently produce sulfate radicals and hydroxyl radicals, but still needs to add two reagents, ozone and sulfite, which has the risk of chemical reagent dependence and by-products. CN118718937A proposes to use high-voltage ionization and light irradiation technology to directly prepare hydroxyl radicals, which has a simple process and can control by-products, but relies on high-voltage power supply and optical systems, which is complex and has high energy consumption. CN117023933A couples in-situ dissimilatory iron reduction with sodium percarbonate Fenton reaction for sludge dewatering, achieving in-situ utilization of iron, but its technical focus is on sludge conditioning, and its universality in wastewater deep treatment needs to be verified.

[0004] Although these existing technologies have innovations in oxidant sources and activation methods, most of them still rely on chemical reagent addition or external energy input. Micro-bubble technology has attracted attention due to its large specific surface area, long residence time, and unique gas-liquid interface properties. Studies have shown that micro-bubbles can enrich hydroxyl ions and induce the generation of free radicals, which provides a new way to initiate and maintain oxidation reactions. Therefore, how to utilize the characteristics of micro-bubbles, combined with inexpensive iron-based catalysts, to construct an efficient and low-cost active oxygen generation system in a wide pH range without relying on external chemical oxidants and complex external energy, has become a valuable research direction. SUMMARY

[0005] In view of the problems in the prior art, the application provides active oxygen and a preparation method and application thereof. The preparation method of the active oxygen provided by the application can initiate and maintain a high-efficiency Fenton-like reaction under acidic and neutral conditions by utilizing the unique gas-liquid interface properties of microbubbles and the electron donor properties of iron-based catalysts, thereby stably producing active oxygen. The method does not require a large amount of hydrogen peroxide to be added, avoids the requirement of a strong acidic environment, uses low-cost raw materials, and is simple and environmentally friendly, thereby greatly expanding the application scenarios of advanced oxidation technology.

[0006] To achieve the above purpose, the application adopts the following technical solutions:

[0007] The application provides a microbubble-assisted iron-based catalyst oxidation degradation method, which comprises the following steps:

[0008] After the water body is pretreated, the iron-based catalyst is introduced into the water body, and then microbubbles are introduced into the water body for oxidation degradation.

[0009] The working principle of the application is mainly based on the synergistic effect of microbubbles and iron-based catalysts. Microbubbles provide a large gas-liquid interface in the solution, and the surface thereof is usually negatively charged (Zeta potential), which can selectively enrich hydroxyl ions and iron ions in the solution to form a special microenvironment that is locally rich in reactants. In this microenvironment, the iron-based catalyst (such as zero-valent iron) acts as an electron donor to transfer electrons to dissolved oxygen on the microbubble interface to generate hydrogen peroxide in situ. Subsequently, the iron-catalyzed Fenton-like reaction is carried out to efficiently convert the hydrogen peroxide into hydroxyl radicals. This synergistic mechanism not only realizes the self-supply of hydrogen peroxide, but also effectively promotes the circulation of iron ions by the enrichment of hydroxyl ions on the microbubble interface, so that the entire reaction chain can be continuously and efficiently carried out under acidic and neutral conditions.

[0010] As a preferred technical solution of the application, the pretreatment comprises adjusting the pH to 3.0-7.0, for example, the pH can be 3.0, 4.0, 5.0, 6.0 or 7.0, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0011] As a preferred technical solution of the application, the pH adjustment comprises using any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid or sodium hydroxide.

[0012] As a preferred technical solution of the application, the iron-based catalyst comprises any one or a combination of at least two of zero-valent iron, magnetite, maghemite or hydroxyl ferrite.

[0013] As a preferred technical solution of the present application, the addition amount of the iron-based catalyst is 0.1-2.0 g / L, for example, it can be 0.1 g / L, 0.8 g / L, 1.3 g / L, 1.8 g / L or 2.0 g / L, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0014] As a preferred technical solution of the present application, the diameter of the microbubble is 1-100 μm, for example, it can be 1 μm, 20 μm, 50 μm, 70 μm, 90 μm or 100 μm, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0015] As a preferred technical solution of the present application, the microbubble includes any one or a combination of at least two of air, oxygen or ozone.

[0016] As a preferred technical solution of the present application, the flow rate of the microbubble is 0.3-0.5 L / min, for example, it can be 0.3 L / min, 0.4 L / min or 0.5 L / min, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0017] As a preferred technical solution of the present application, the time of oxidative degradation is 45-90 min, for example, it can be 45 min, 60 min, 75 min, 85 min or 90 min, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0018] As a preferred technical solution of the present application, the temperature of oxidative degradation is 20-30℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃ or 450℃, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0019] Compared with the prior art, the present application has at least the following beneficial effects:

[0020] Through the synergistic effect of microbubbles and iron-based catalyst, efficient and sustained generation of hydroxyl radicals under acidic and neutral conditions without relying on a large amount of additional hydrogen peroxide is successfully achieved, which fundamentally overcomes the dependence of traditional Fenton technology on strong acidic environment and hazardous chemicals, significantly reduces the treatment cost and operation risk, and reduces metal secondary pollution, providing a new way for green, economic and wide application of advanced oxidation technology. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present application, the present application lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present application and should not be regarded as a specific limitation on the present application.

[0022] Example 1

[0023] The present embodiment provides a method for micro-bubble assisted oxidation degradation of iron-based catalyst, which comprises the following steps:

[0024] (1) Preparation: 1 L of phenol wastewater with an initial concentration of 100 mg / L was prepared as the water body to be treated, and the pH value of the water body was adjusted to 6.5 using dilute sulfuric acid, which was recorded as the reaction stock solution;

[0025] (2) Catalyst addition: zero-valent iron powder was added to the above reaction stock solution as the iron-based catalyst, and the addition amount was 0.5 g / L;

[0026] (3) Micro-bubble introduction: the reaction stock solution after catalyst addition was transferred to a micro-bubble reactor, and micro-bubbles were introduced into the reaction stock solution through a micro-bubble generator at room temperature (25°C) with air as the gas source, the gas flow rate was set to 0.5 L / min, the average diameter of the generated micro-bubbles was 50 μm, and the reaction time was 60 min;

[0027] (4) Filtration and analysis: after the reaction was completed, the reaction solution was filtered, and the concentration of phenol in the filtrate was analyzed by high performance liquid chromatography. The detected concentration of phenol in the filtrate was 4.7 mg / L. Based on the difference in the concentration of phenol before and after the reaction, the removal rate of phenol was calculated to be 95.3%. At the same time, electron paramagnetic resonance spectroscopy detection confirmed that a large amount of hydroxyl radicals were generated in the reaction system.

[0028] Example 2

[0029] The present embodiment provides a method for micro-bubble assisted oxidation degradation of iron-based catalyst, which comprises the following steps:

[0030] (1) Pretreatment: 1 L of methylene blue dye wastewater with an initial concentration of 50 mg / L was prepared as the water body to be treated, and the pH value of the water body was adjusted to 4.0 using dilute hydrochloric acid, which was recorded as the reaction stock solution;

[0031] (2) Catalyst addition: ferric oxide was added to the above reaction stock solution as the iron-based catalyst, and the addition amount was 0.8 g / L;

[0032] (3) Micro-bubble introduction: the reaction stock solution after catalyst addition was transferred to a micro-bubble reactor, and micro-bubbles were introduced into the reaction stock solution through a micro-bubble generator at room temperature (25°C) with oxygen as the gas source, the gas flow rate was set to 0.3 L / min, the average diameter of the generated micro-bubbles was 20 μm, and the reaction time was 45 min;

[0033] (4) Oxidation reaction: After the reaction, the reaction solution was filtered, and the concentration of methylene blue in the filtrate was analyzed by UV-visible spectrophotometry. The concentration of methylene blue in the filtrate was 2.1 mg / L. Based on the concentration difference before and after the reaction, the removal rate of methylene blue was calculated to be 95.8%. At the same time, it was confirmed by electron paramagnetic resonance spectrum detection that a large number of hydroxyl radicals were generated in the reaction system.

[0034] Example 3

[0035] The embodiment provides a method for microbubble-assisted iron-based catalyst oxidation degradation, which comprises the following steps:

[0036] (1) Pretreatment: 1 L of atrazine wastewater with an initial concentration of 30 mg / L was configured as a water body to be treated, and the pH value of the water body was adjusted to 5.5 using dilute nitric acid, which was recorded as a reaction stock solution;

[0037] (2) Catalyst addition: Hydroxyl iron oxide was added to the above reaction stock solution as an iron-based catalyst, and the addition amount was 1.2 g / L;

[0038] (3) Microbubble introduction: The reaction stock solution after catalyst addition was transferred to a microbubble reactor, and microbubbles were introduced into the reaction stock solution by a microbubble generator at room temperature (25°C) using air and ozone mixed gas (volume ratio 4:1) as the gas source, the gas flow rate was set to 0.4 L / min, the average diameter of the generated microbubbles was 10 μm, and the reaction time was 90 min;

[0039] (4) Oxidation reaction: After the reaction, the reaction solution was filtered, and the concentration of atrazine in the filtrate was analyzed by high performance liquid chromatography. The concentration of atrazine in the filtrate was 1.8 mg / L. Based on the concentration difference before and after the reaction, the removal rate of atrazine was calculated to be 94.0%. At the same time, it was confirmed by electron paramagnetic resonance spectrum detection that a large number of hydroxyl radicals were generated in the reaction system.

[0040] Example 4

[0041] The embodiment provides a method for microbubble-assisted iron-based catalyst oxidation degradation, which comprises the following steps:

[0042] (1) Pretreatment: 1 L of simulated acid mine wastewater was configured, wherein the Fe 2+ The initial concentration was 150 mg / L, and the pH value of the water body was adjusted to 5.0 using a small amount of sodium hydroxide solution, which was recorded as a reaction stock solution;

[0043] (2) adding catalyst: adding ferroferric oxide as an iron-based catalyst to the above reaction stock solution, the dosage is 0.5 g / L. The catalyst not only can catalyze the reaction, but also can be used as a crystal nucleus to promote the separation of the subsequent formed iron precipitate;

[0044] (3) passing micro-bubbles: transferring the reaction stock solution after adding catalyst to a micro-bubble reactor, at room temperature (25℃), passing micro-bubbles into the reaction stock solution through a micro-bubble generator with air as the gas source, the gas flow rate is set to 0.5 L / min, the average diameter of the generated micro-bubbles is 40 μm, and the reaction time is 60 min;

[0045] (4) oxidation reaction and precipitation: under the synergistic action of micro-bubbles and iron-based catalyst, the continuously generated active oxygen (such as hydroxyl radical) in the system will dissolve Fe 2+ into Fe 3+ . After the reaction, the Fe 3+ hydrolyzes to generate iron hydroxide precipitate;

[0046] After the reaction, the supernatant is filtered, and the concentration of residual Fe 2+ in the filtrate is determined by o-phenanthroline spectrophotometry. The concentration of Fe 2+ in the filtrate is 8.5 mg / L. Based on the concentration difference before and after the reaction, the oxidation removal rate of Fe 2+ is calculated to be 94.3%. This method realizes the efficient oxidation and preliminary removal of dissolved iron in wastewater under near neutral conditions, and creates favorable conditions for subsequent deep treatment and neutralization precipitation.

[0047] Performance test

[0048] The filtrates obtained in Examples 1-4 are tested by high performance liquid chromatography analysis and electron paramagnetic resonance spectroscopy, and the results are shown in Table 1.

[0049] Table 1

[0050]

[0051] The above examples illustrate the detailed structural features of the present application, but the present application is not limited to the above detailed structural features, i.e. it does not mean that the present application must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for microbubble-assisted oxidation degradation of an iron-based catalyst, characterized by, The method comprises the following steps: The water body is introduced into an iron-based catalyst after pretreatment, and then micro-bubbles are introduced into the water body to perform oxidative degradation.

2. The method of claim 1, wherein, The pretreatment comprises adjusting the pH to 3.0-7.

0.

3. The method of claim 2, wherein, The pH adjustment comprises using any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid or sodium hydroxide.

4. The method according to any one of claims 1 to 3, characterized in that, The iron-based catalyst comprises any one or a combination of at least two of zero-valent iron, ferroferric oxide, diiron trioxide or hydroxyl ferric oxide.

5. The method according to any one of claims 1 to 4, characterized in that, The addition amount of the iron-based catalyst is 0.1-2.0 g / L.

6. The method according to any one of claims 1 to 5, characterized in that, The diameter of the micro-bubbles is 1-100 μm.

7. The method according to any one of claims 1 to 6, characterized in that, The micro-bubbles comprise any one or a combination of at least two of air, oxygen or ozone.

8. The method according to any one of claims 1 to 7, characterized in that, The flow rate of the micro-bubbles is 0.3-0.5 L / min.

9. The method according to any one of claims 1 to 8, characterized in that, The time for the oxidative degradation is 45-90 min.

10. The method according to any one of claims 1 to 9, characterized in that, The temperature for the oxidative degradation is 20-30℃.

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