Method for removing organic pollutants in water by combining electric flocculation and peracetic acid

Abstract

The invention discloses a method for removing organic pollutants in water through combination of electric flocculation and peracetic acid, and belongs to the technical field of water treatment.The method comprises the following steps that a certain amount of peracetic acid is added into water to be treated, flocculation treatment is conducted on a water solution to be treated through an electric flocculation reaction device, and the water solution to be treated is obtained; the power supply device is utilized to enable the anode plate in the electric flocculation device to separate out corresponding metal ions under the action of specific current, and then hydroxide flocculent precipitates are further formed. The added peracetic acid interacts with hydroxides formed by flocculation in the system to generate active substances such as OH, CH3C (O) OO and CH3C (O) OO to promote removal of pollutants, and part of pollutants which are not completely degraded can be removed by high-activity floc groups generated in the system through adsorption, coprecipitation and the like. The device can realize a rapid and efficient organic pollutant removal effect, and has the characteristics of simplicity and convenience in operation, stable performance, small occupied area, low energy consumption and the like.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, in particular to a method for removing organic pollutants in water by combining electric flocculation with peracetic acid. Background Art

[0002] The presence of organic pollutants in the water environment has led to increasingly complex water environment components and increased toxicity. Toxic and harmful substances that remain in the water for a long time will pose a great potential threat to the ecosystem and even endanger the life and health of humans and animals.

[0003] Peracetic acid is a common oxidant and disinfectant. Due to its high disinfection efficiency and few harmful byproducts, it has been widely used in food processing and medical and health industries for sterilization and disinfection. Currently, there are methods that use heat energy, ultraviolet rays, etc. to act on peracetic acid to enhance its disinfection or oxidation ability. However, these methods have limited efficiency and high energy consumption, making it difficult to promote practical applications. Therefore, an efficient and low-cost utilization method needs to be found.

[0004] In addition, conventional water treatment processes have the disadvantages of incomplete removal of pollutants, long treatment cycle and high cost when treating wastewater containing organic pollutants. Therefore, it is urgent to explore a fast and efficient method for treating organic pollutants. Electrochemically mediated advanced oxidation technology for water treatment has the advantages of simple operation, high treatment efficiency and high integration, and is expected to solve the severe situation facing the current water environment. Although the electrocoagulation technology developed on the basis of electrochemistry has the advantages of convenient operation, rapid and efficient, low sludge volume and simple device, and its application in water treatment is increasing, when the traditional electrocoagulation process is used for the comprehensive treatment of highly toxic and harmful pollutants such as difficult-to-degrade organic matter, there may also be potential secondary pollution, such as the release of toxic and harmful pollutants that have been retained in the sediment for a long time. Therefore, the development of an enhanced technology for electrocoagulation process is crucial to solving the current situation of organic pollutants facing the water environment. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of incomplete degradation of pollutants in the existing electro-flocculation process and difficulty in effectively utilizing peracetic acid, and to provide a novel electro-flocculation-peracetic acid combined technology, which can be effectively used for the treatment of organic pollutants in water environments and can achieve high-efficiency and low-cost pollutant removal effects within a wide pH range (pH=4-8).

[0006] To achieve the above object, the present invention is implemented according to the following technical solutions: A method for removing organic pollutants in water by combining electrocoagulation with peracetic acid comprises the following steps: A certain amount of peracetic acid is added to the water to be treated, and the water solution to be treated is flocculated by an electric flocculation reaction device, that is, a power supply device is used to make the metal anode precipitate metal cations under the action of a specific current. These ions can then further react with OH in the system. - The added peracetic acid interacts with the hydroxides formed in the system to produce • OH, CH3C(O)O • 、 CH3C(O)OO • Active substances such as cellulose promote the oxidative degradation of pollutants, and some pollutants that are not completely degraded can be removed by highly active flocculent groups through adsorption, co-precipitation, etc.

[0007] Preferably, the anode used in the electro-flocculation reaction device is an iron electrode or an iron-containing electrode material.

[0008] As a preferred experimental scheme of the present invention, the peracetic acid is an aqueous solution of peracetic acid with an active ingredient content of ≥15%.

[0009] As a preferred experimental scheme of the present invention, the electro-flocculation reaction device is made of organic glass or quartz glass and has a cylindrical or rectangular shape.

[0010] As a preferred experimental scheme of the present invention, the power supply device of the electric flocculation reaction device is a direct current power supply or a pulse power supply.

[0011] As a preferred experimental scheme of the present invention, the electrode plates of the electric flocculation reaction device are arranged in parallel.

[0012] As a preferred experimental scheme of the present invention, the current intensity of the flocculation treatment is 0.001~1 A.

[0013] As a preferred experimental scheme of the present invention, the initial pH of the aqueous solution to be treated is 4-8.

[0014] As a preferred experimental scheme of the present invention, the flocculation treatment is carried out under stirring, and the stirring can be achieved by magnetic stirring, pneumatic stirring or circulating stirring.

[0015] As a preferred experimental scheme of the present invention, the amount of peracetic acid added in step 1) is 100 μM / L.

[0016] The beneficial effect of the present invention is that the method of the present invention uses electrocoagulation and peracetic acid to remove organic pollutants in water, which can achieve a rapid and efficient removal effect of organic pollutants in water. The electrode plate used in the method can be reused, and a good pollutant removal effect can be achieved in a wide pH range (pH=4~8). It has the characteristics of convenience, high efficiency, low cost, stable performance, small footprint, etc., and provides a technical means with potential application value for the treatment of wastewater containing organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the electrocoagulation reaction device of the present invention; Figure 2 This is the removal effect diagram of chloramphenicol under different reaction systems; Figure 3 This is a diagram showing the removal effect of chloramphenicol at different current densities; Figure 4 This is a diagram showing the removal effect of chloramphenicol under different pH conditions. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical methods and advantages of the embodiments of the present invention clearer, the technical methods in the embodiments of the present invention will be clearly described below in combination with the specific embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention. Based on the specific embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0019] All raw materials of the present invention have no particular limitation on their sources and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0020] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts the conventional purity used in the art.

[0021] The experimental device used in the present invention is not particularly limited, and commonly used experimental devices in the art are adopted.

[0022] In the following examples and comparative examples, Figure 1 The electro-flocculation reaction device shown. The anode used in the electro-flocculation reaction device can be an iron electrode or an iron-containing electrode material. In the following embodiments and comparative examples, the electro-flocculation treatment uses a metal iron plate as the anode and a stainless steel plate as the cathode. The container material of the electro-flocculation reaction device can be organic glass or quartz glass, and the shape can be cylindrical or rectangular. In the following embodiments, an organic glass cylindrical container is used. The electrode plates are arranged in parallel.

[0023] The experimental steps are as follows: add the water to be treated into the reaction device, add a certain amount of peracetic acid, turn on the power supply and stirring device, and adjust the current intensity to a suitable level. The metal anode precipitates metal cations under the action of a specific current, and then reacts with OH in the system. - The added peracetic acid interacts with the hydroxides formed in the system to produce • OH, CH3C(O)O • 、 CH3C(O)OO • Active substances such as cellulose promote the oxidative degradation of pollutants, and some pollutants that are not completely degraded can be removed by highly active flocculent groups through adsorption, co-precipitation, etc. Wherein, the peracetic acid is an aqueous solution of peracetic acid with an active ingredient content of ≥15%. The following examples and comparative examples use an aqueous solution of peracetic acid with an active ingredient content of 15%.

[0024] Among them, the current intensity of the electric flocculation reaction device is 0.001~1 A.

[0025] The initial pH value of the aqueous solution to be treated is 4-8.

[0026] After each reaction, a certain volume of reaction liquid was immediately taken from the reaction device and centrifuged to separate the floccules and the supernatant, and the pollutant concentration was detected by high performance liquid chromatography.

[0027] Example 1 and Comparative Examples 1-4 compare the application effects of different treatment systems in degrading simulated chloramphenicol-containing wastewater: Example 1 Treatment system 1 (electrocoagulation-peracetic acid system, i.e., EC / PAA system) was set with an initial chloramphenicol concentration of 10 μM / L, and Na2SO4 was used as the electrolyte of the system to adjust the solution conductivity. The DC power supply current intensity was set to 0.001-1 A, and the current density was set to 0.50 mA cm -2 100 μM / L peracetic acid was added, the initial pH value of the system was 6, the magnetic stirring device was turned on, the reaction was carried out at room temperature, sampling was carried out at regular time intervals and the changes in pollutant concentration were detected, and the total reaction time was 50 min.

[0028] Comparative Example 1 Treatment system 2 (single electrocoagulation system, i.e., EC system) did not add peracetic acid, and the rest of the process was the same as in Example 1.

[0029] Comparative Example 2 Treatment system 3 (peracetic acid system, ie, PAA system) does not use an electric flocculation reaction device, and the rest of the process is consistent with Example 1.

[0030] Comparative Example 3 Treatment System 4 (Fe 2+ =5 μm -peracetic acid system, namely Fe 2+ / PAA(Fe 2+ =5 μm) system), electrocoagulation was not used, 5 μm / L FeSO4 was added, and the rest of the process was consistent with Example 1.

[0031] Comparative Example 4 Treatment System 5 (Fe 2+ =100 μm -peracetic acid system, namely Fe 2+ / PAA(Fe 2+ =100 μm) system), electrocoagulation was not used, 100 μm / L FeSO4 was added, and the rest of the process was consistent with Example 1.

[0032] Depend on Figure 2 It can be seen that the removal efficiency of chloramphenicol by the electrocoagulation-peracetic acid system (EC / PAA) can reach 96%, which is significantly better than the single electrocoagulation system (EC).

[0033] Examples 2-4 are used to compare the effects of different current densities on the implementation effects of the present invention with Example 1.

[0034] Example 2 The difference from Example 1 is that in this embodiment, the current density of the DC power supply during the electrocoagulation treatment is set to 0.50 mA cm -2 .

[0035] Example 3 The difference from Example 1 is that the current density of the DC power supply during the electrocoagulation treatment in this embodiment is set to 1.00 mA cm -2 .

[0036] Example 4 The difference from Example 1 is that the current density of the DC power supply during the electrocoagulation treatment in this embodiment is set to 2.00 mA cm -2 .

[0037] The effect of chloramphenicol removal rate on current density is as follows Figure 3 As shown, it indicates that with the increase of current, more porous hydroxide flocs may be produced in the electro-flocculation process, which is more conducive to the removal of pollutants.

[0038] Examples 5-6 are used to compare the effects of different initial pH conditions on the treatment effect with Example 1. The pH values ​​of the reaction systems are adjusted to 4 to 8 respectively using 0.1 to 1 mol / L HCl or NaOH solutions. The subsequent specific operating steps are the same as those in Example 1.

[0039] Example 5 The pH value of the reaction system was adjusted to 4 with HCl solution, and the rest of the process was consistent with Example 1.

[0040] Example 6 The pH value of the reaction system was adjusted to 6 with NaOH solution, and the rest of the process was the same as in Example 1.

[0041] Example 7 The pH value of the reaction system was adjusted to 7 with NaOH solution, and the rest of the process was the same as in Example 1.

[0042] Example 8 The pH value of the reaction system was adjusted to 8 with NaOH solution, and the rest of the process was the same as in Example 1.

[0043] Figure 4 The results show that the electrocoagulation and peracetic acid system can achieve good pollutant removal effects in a wide pH range (pH=4-8), indicating that the system can adapt to a wider range of application scenarios.

[0044] From the above, it can be seen that the electrocoagulation-peracetic acid combination technology used in the method of the present invention is used for the removal of organic pollutants. The technical method is simple to operate and easy to implement. The electrode plates used are reusable and can achieve good pollutant removal effects within a wide pH range (pH=4~8). The method has the characteristics of convenience, high efficiency, low cost, stable performance, and small footprint, and provides broad application prospects in the field of wastewater treatment containing organic pollutants.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for removing organic pollutants in water by combining electrocoagulation with peracetic acid, characterized in that: The following steps are involved: 1) adding peracetic acid to the water to be treated to form an aqueous solution to be treated; 2) The aqueous solution to be treated is flocculated by an electric flocculation reaction device.

2. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The peracetic acid is a peracetic acid aqueous solution with an active ingredient content of ≥15wt%.

3. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The metal anode of the electro-flocculation reaction device is an iron electrode or an iron-containing electrode material.

4. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The container material of the electric flocculation reaction device is organic glass or quartz glass, and the shape is cylindrical or rectangular.

5. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The power supply device of the electric flocculation reaction device is a direct current power supply or a pulse power supply.

6. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The electrode plates of the electric flocculation reaction device are arranged in parallel.

7. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The current intensity of the flocculation treatment is 0.001~1 A.

8. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The initial pH of the aqueous solution to be treated is 4-8.

9. The method for removing organic pollutants in water by combining electrocoagulation and peracetic acid according to claim 1, characterized in that: The flocculation treatment is carried out under stirring.

10. The method for removing organic pollutants in water by combining electro-flocculation and peracetic acid according to claim 1, characterized in that: The amount of peracetic acid added in step 1) is 100 μM / L.

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