Wastewater treatment method for activating ozone through cooperation of magnetic field and electricity

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly discloses a wastewater treatment method for activating ozone through cooperation of a magnetic field and electricity, which comprises the following steps: (1) placing wastewater in a closed container, and adjusting the pH value to obtain a reaction solution; (2) introducing ozone gas into the reaction liquid and electrifying to carry out electrochemical activation reaction; (3) carrying out an electrochemical activation reaction on the reaction liquid in the step (2) and carrying out magnetic field instantaneous magnetization on the reaction liquid at the same time; and (4) circulating the steps (2)-(3) to the reaction liquid instantly magnetized by the magnetic field until the wastewater meets the standard requirement. The invention combines the advantages of magnetic field, electricity and ozone oxidation, constructs and develops an efficient magnetic field and electricity synergistic ozone activation technology, enhances the process of generating. OH free radicals by electro-activated ozone through magnetization so as to improve the oxidation efficiency and enhance the reaction activity of ozone, realizes efficient degradation of pollutants under actual conditions, and has a wide application prospect. And theoretical basis and engineering guidance are provided for high-concentration degradation-resistant wastewater and deep water treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a wastewater treatment method for synergistically activating ozone by a magnetic field and electricity. Background Art

[0002] Industrial wastewater has multiple components, is complex and difficult to degrade. If directly discharged into environmental water bodies, it will cause inestimable damage to ecological environments such as water bodies and soils, posing a great threat to human health. Industrial wastewater contains a large amount of organic matter and chemical substances. Therefore, special treatment processes are usually required to purify the wastewater to meet national and local sewage discharge standards. Common treatment technologies for refractory wastewater include biological treatment technology, physical removal technology, chemical oxidation technology, etc.

[0003] Chemical oxidation technology (AOPs) is an enhanced chemical treatment method. The common feature of such technologies is the use of chemical oxidants to generate free radicals with high oxidation potentials (such as hydroxyl radicals (·OH), sulfate radicals (·SO4 - ), superoxide radicals (·O2 - ), etc.). Among them, advanced oxidation technologies based on ozone oxidation are widely used in sewage treatment. Although ozone has strong oxidation ability, ozone also has problems such as low solubility, poor stability, high production cost, and selective oxidation. Therefore, on the basis of ozone oxidizing pollutants in water, the catalytic oxidation technology of ozone has gradually taken shape. Common methods for catalytic ozone include hydrogen peroxide, ultraviolet, ultrasonic, material catalysis, electrocatalysis, magnetic catalysis, etc. However, these catalytic oxidation methods of ozone still have the problem of low degradation efficiency. Summary of the Invention

[0004] In view of this, the present invention provides a wastewater treatment method for synergistically activating ozone by a magnetic field and electricity. By combining the advantages of magnetic field, electricity, and ozone oxidation, a high-efficiency technology for synergistically activating ozone by a magnetic field and electricity is constructed and developed. The magnetization is used to enhance the process of electro-activating ozone to generate ·OH free radicals to improve the oxidation efficiency. The present invention can enhance the scientific understanding of the synergy between different activation technologies and ozone, enhance the reaction activity of ozone, promote the deep participation of ozone in the reaction, achieve the efficient degradation of pollutants under actual conditions, and provide a theoretical basis and engineering guidance for advanced water treatment.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A wastewater treatment method for synergistically activating ozone by a magnetic field and electricity, comprising the following steps:

[0007] (1) Place the wastewater in a closed container and adjust the pH value to obtain a reaction solution;

[0008] (2) Introduce ozone gas into the reaction solution and apply electricity to carry out an electrochemical activation reaction;

[0009] (3) While carrying out the electrochemical activation reaction on the reaction solution in step (2), instantaneously magnetize the reaction solution with a magnetic field;

[0010] (4) Recycle the reaction solution after instantaneous magnetic field magnetization through steps (2) to (3) until the wastewater meets the standard requirements.

[0011] Preferably, in step (1), the pH value of the wastewater is adjusted to 8 - 10.

[0012] Preferably, in step (2), ozone gas is introduced into the reaction solution, and the introduction amount is 0.4 - 0.5 L / min.

[0013] Preferably, in step (2), the electrochemical activation reaction is carried out by a constant current method, and the current density is 3.33 mA / cm 2 .

[0014] Preferably, in step (2), stirring is carried out during the electrochemical activation reaction, the stirring rate is 500 - 1000 rpm, and the reaction temperature is 10 - 20 °C.

[0015] Preferably, in step (3), the instantaneous magnetic field magnetization is carried out through an external magnetic field or an electromagnetic field arranged inside and / or outside a closed container;

[0016] The external magnetic field is a long-term magnetic field; the electromagnetic field is an instantaneous magnetic field.

[0017] Preferably, the intensity of the magnetic field ≥ 0.8 T.

[0018] Preferably, in step (3), the magnetization time of the reaction solution in the magnetic field is 0.006 s.

[0019] According to the above technical solutions, compared with the prior art, the present invention has the following excellent effects:

[0020] The present invention combines the electro-activated ozonation of ozone advanced oxidation with magnetic field-catalyzed ozone, and proposes a technical path of introducing strong magnetic field instantaneous magnetization catalysis during the process of electro-activated ozone treatment of wastewater. An electrochemical reaction system with direct current introduced into the anode and cathode of the reaction solution is designed. While introducing O3 gas into the system, the liquid system undergoes pulsed instantaneous magnetization treatment. Through the discussion and research on the efficacy mechanism of the synergistic process for degrading organic pollutants, the process parameters and reaction conditions are reasonably designed, and a new type of equipment more suitable for actual treatment is designed. The feature of the present invention is that it combines magnetic field catalysis technology, electro-activation technology and ozone oxidation technology, gives full play to the advantages of each technology, improves the efficiency and degradation effect of wastewater treatment, and has high engineering application value and market potential. Brief Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0022] Figure 1 It is a wastewater treatment experimental device diagram for the synergistic activation of ozone by magnetic field and electricity in the present invention. Among them, (a) is the experimental device diagram of the external magnetic field, and (b) is the experimental device diagram of arranging the electromagnetic field outside the closed container.

[0023] Figure 2 It is a degradation efficiency diagram of the related system in Embodiment 1 of the present invention for wastewater (reactive yellow K-RN).

[0024] Figure 3 It is the degradation efficiency of the electro-magnetic-ozone system for wastewater (reactive yellow K-RN) under different ozone input amounts in Embodiment 1 of the present invention.

[0025] Figure 4 It is the degradation efficiency of the electro-magnetic-ozone system for wastewater (reactive yellow K-RN) under different current densities in Embodiment 1 of the present invention.

[0026] Figure 5 It is the degradation efficiency of the electro-magnetic-ozone system for wastewater (reactive yellow K-RN) under different initial pH values in Embodiment 1 of the present invention.

[0027] Figure 6 It is the mineralization efficiency of different systems in Embodiment 1 of the present invention for wastewater (reactive yellow K-RN).

[0028] Figure 7 It is the EPR test result of oxygen free radicals in different systems in Embodiment 1 of the present invention.

[0029] Figure 8 It is a physical diagram of the actual wastewater sample using the electro-magnetic-ozone system (E+M+O3) at different degradation times. Detailed implementation manners

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] Embodiment 1

[0032] Experimental materials and methods

[0033] 1.1 Method for preparing simulated wastewater

[0034] Reactive Yellow KM-RN (also known as Reactive Yellow K-RN C 27 H 18 ClN8Na3O 10 After the sample of S3) is dried at 102 °C for 2 hours, a certain amount is weighed, dissolved in a small amount of deionized water in a beaker, fully stirred and dissolved with deionized water, cooled to room temperature and fixed volume to a 500 mL volumetric flask to prepare a 0.2 mM / L Reactive Yellow K-RN solution.

[0035] All the chemical reagents used in this experiment are of analytical pure grade.

[0036] 1.2 Experimental device

[0037] The experimental device is as Figure 1 shown in a. All subsequent experiments are completed through this device. The experiment is carried out in a cylindrical acrylic reactor with a volume of 700 mL. Two cylindrical electrode clamps are vertically fixed on the container cover. The anode and cathode of the experimental electrode both use titanium-plated platinum electrodes. The size of the electrode plates is 5.0 cm × 3.5 cm, the distance between the electrode plates is 2.5 cm, and the electrode plates are parallel to each other and perpendicular to the reactor and fixed on the electrode clamps. There are also a sampling port and a ventilation port on the reactor cover. Ozone is generated from oxygen, and the ozone generator can convert oxygen into a mixed gas of ozone and oxygen. The flow rate of the mixed gas is adjusted and controlled by a gas flow meter. The constant current method is used for all experiments; the current is generated by a DC constant current and constant voltage power supply. The reactor is placed on a magnetic stirrer. There are also a liquid inlet and a liquid outlet on the reactor. The inlet of the circulating water pump is connected to the liquid outlet, the outlet of the water pump is connected to the inlet of the external magnetic field, and the outlet of the external magnetic field is connected to the liquid inlet. The water pump pumps the liquid in the reactor to the external magnetic field for catalysis. The external magnetic field is generated by a ring magnet.

[0038] 1.3 Method for treating wastewater by synergistic activation of ozone by magnetic field and electricity

[0039] (1) Add anhydrous sodium sulfate to the 0.2 mM / L Reactive Yellow K-RN solution of simulated wastewater to form a reaction solution (anhydrous sodium sulfate is a pure crystal electrolyte that only provides conductivity, and its concentration in the reaction solution is 0.05 M), adjust the pH = 9, and put it into the reactor;

[0040] (2) Pass ozone gas into the reaction solution and simultaneously turn on the circulating water pump and power on for electrochemical activation reaction;

[0041] (3) Pass the reaction solution after the electrochemical activation reaction in step (2) into the external magnetic field for instantaneous magnetic catalysis;

[0042] (4) The reaction solution after instantaneous magnetic field catalysis is returned to the closed container for electrochemical activation reaction again.

[0043] 2.1 Evaluation of the removal efficiency of reactive yellow K-RN in water by related systems

[0044] The present invention compares the removal efficiencies of reactive yellow K-RN by a single electrolysis system (Electrolysis), a single ozone oxidation system (O3), an electro-ozone oxidation system (E+O3), a magnetic-ozone oxidation system (M+O3), and an electro-magnetic-ozone system (E+M+O3).

[0045] Calculation of system synergy

[0046] To further evaluate the removal efficiency of the electro-magnetic-ozone system (E+M+O3) for different pollutants, the synergy coefficients (SI, Synergy indices) of each synergy system were calculated using a formula to evaluate the synergy efficiency of each synergy system.

[0047]

[0048] In the experiment, each system was adjusted based on the wastewater treatment method of synergistically activating ozone with a magnetic field of 1.3 and electricity. The omitted or unopened synergistic parts were omitted or closed. Other experimental conditions were as follows: the concentration of oxygen was 96%, the conversion rate of oxygen to ozone was 80%, the inlet flow rate was 0.4 L / min; the initial pH of the reaction solution was 9, the applied current was 50 mA (3.3 mA / cm 2 ), the stirring rate was 700 rpm, the overall experimental device was placed in a water bath to ensure that the experimental temperature was controlled at 10 °C, the magnetic field residence time (magnetization time) was 0.006 s, and the magnetic field intensity was 0.9 T.

[0049] The experimental results of the degradation of reactive yellow K-RN by different systems are as Figure 2 shown.

[0050] As Figure 2As shown, the removal efficiency of reactive yellow K-RN by the individual electrolysis system and the individual magnetic field system (O3) is very low; the electro-ozone oxidation system (E+O3) and the magnetic-ozone oxidation system (M+O3) have improved compared to the individual systems, indicating that electricity can activate ozone and magnetism can also activate ozone. The two synergistic systems have a certain oxidative degradation effect on some refractory organic pollutants. Compared with other systems, the electro-magnetic-ozone system (E+M+O3) has a higher removal efficiency, far higher than the sum of the degradation rates of the individual electrolysis (Electrolysis), individual ozone oxidation (O3), and individual magnetic field (M) systems. Compared with other systems, the pseudo-first-order reaction kinetic constant of the electro / magnetic / ozone system (E+M+O3) is much higher than that of other systems, and its synergistic coefficient SI (4.2649 s -1 ) is also greater than that of other coupled systems. This once again shows that compared with other systems, the electro / magnetic / ozone system (E+M+O3) has better oxidative efficiency and synergistic effect on reactive yellow K-RN, indicating that this system can effectively improve the removal efficiency of reactive yellow K-RN..

[0051] Table 1 Synergistic index of different methods for the removal of reactive yellow K-RN

[0052]

[0053] 2.2 Effect of different ozone flow rates on the removal efficiency of reactive yellow K-RN in water by the electro-magnetic-ozone system (E+M+O3)

[0054] In the electro-magnetic-ozone system (E+M+O3), the addition of ozone introduces reactive substances such as hydroxyl radicals (·OH) into the system. Therefore, the ozone flow rate may affect the removal efficiency of this system for reactive yellow K-RN. In this experiment, other reaction conditions in Experiment 2.1 were maintained unchanged. On the premise of controlling the ozone concentration unchanged, the flow rate was changed, and the flow rates were set to 0 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, and 0.5 L / min. The specific experimental results are as Figure 3 shown.

[0055] The effect of the ozone flow rate on the degradation efficiency of reactive yellow K-RN by this system is as Figure 3As shown, after ozone is introduced into the system, the removal effect of the system on reactive yellow K-RN is improved. As the flow rate increases from 0.3 L / min to 0.4 L / min, the degradation rate of the system on reactive yellow K-RN increases from 38.36% to 90.19%, an increase of 51.83%. When the flow rate is further increased to 0.5 L / min, it is found that the degradation efficiency of the system on reactive yellow K-RN only increases by 4.84%. This shows that even if the ozone concentration is further increased, the amount of ozone that can be effectively utilized is limited, which may cause waste due to the overflow of excess ozone gas. Therefore, considering economic factors, the optimal flow rate is 0.4 L / min.

[0056] 2.3 Effect of different current densities on the removal efficiency of electro-magnetic-ozone system (E+M+O3) on reactive yellow K-RN in water

[0057] Current can reduce ozone at the cathode to generate hydroxyl radicals (·OH). Therefore, the current density is also an important factor in the electrocatalytic ozone oxidation process. In this experiment, other reaction conditions in 2.1 were maintained unchanged, and the removal efficiency of the electro-magnetic-ozone system (E+M+O3) on reactive yellow K-RN was investigated when the current density was 0.66 mA / cm 2 -3.33 mA / cm 2 The calculation method of the current density is shown in the formula. The specific experimental results are as Figure 4 shown.

[0058]

[0059] In the formula: I - direct current (mA);

[0060] A - relative area of the electrode (cm 2 ), which is 15 cm in this experiment 2 .

[0061] As Figure 4 shown, when the current density is increased from 0.6 mA / cm 2 to 3.3 mA / cm 2 , as the current increases, its catalytic effect on ozone increases. However, when the current density is increased from 3.3 mA / cm 2 to 5.7 mA / cm 2 , the removal efficiency of the system on reactive yellow K-RN decreases instead, indicating that the reaction efficiency does not always increase as the current density increases. In this experiment, the optimal current density was determined to be 3.33 mA / cm 2 , that is, a direct current of 50 mA is introduced into the system.

[0062] 2.4 Effect of Different Initial pH Values on the Removal Efficiency of Reactive Yellow K-RN in Water by the Electro-Magnetic-Ozone System (E+M+O3)

[0063] The pH of the solution has an important effect on the efficiency of advanced oxidation processes (AOPs) in removing organic pollutants, which affects the distribution form of organic pollutants in the solution and the generation of free radicals during the advanced oxidation process. In this experiment, other reaction conditions in Experiment 2.1 were maintained unchanged, and the effect of different initial pH values of the reaction solution on the efficiency of the electro-magnetic-ozone system (E+M+O3) in removing Reactive Yellow K-RN was investigated. Other reaction conditions were maintained unchanged, and the initial pH value of the solution was adjusted to 3, 5, 7, 9, and 11. The experimental results are as Figure 5 shown.

[0064] As Figure 5 known, when the initial pH value of the solution was adjusted to 3, 5, 7, 9, and 11, the efficiency of the system in degrading Reactive Yellow K-RN gradually decreased, then increased, and then decreased again. When the initial pH value of the solution was 9, the degradation efficiency of the system for Reactive Yellow K-RN was the best.

[0065] 2.5 Comparison of the Mineralization Efficiencies of Different Systems for Reactive Yellow K-RN in Water

[0066] The degree of mineralization of organic pollutants is an important factor in evaluating the efficiency of an advanced oxidation system, because the intermediate by-products of the incomplete oxidation of refractory organic compounds may have greater biotoxicity than the organic compounds themselves, posing a greater potential hazard to the natural water environment.

[0067] During the degradation of Reactive Yellow K-RN by five systems, namely the single electrolysis system (Electrolysis), the single ozone oxidation system (O3), the electro-ozone oxidation system (E+O3), the magnetic-ozone oxidation system (M+O3), and the electro-magnetic-ozone system (E+M+O3), the removal efficiency of total organic carbon (TOC, Total Organic Carbon) was investigated. The specific experimental conditions were the same as those in the degradation rate experiment in 2.1.

[0068] As Figure 6As shown, the mineralization effects of the individual electrolysis system and the individual ozone oxidation system (O3) on reactive yellow K-RN are not ideal, with mineralization rates of only 2.8% and 13.9% respectively achieved within 180 min of reaction. The binary synergistic systems have a certain improvement in the mineralization of reactive yellow K-RN compared to the individual systems. The electro-magnetic system (E+M), the magnetic-ozone system (M+O3), and the electro-ozone system (E+O3) mineralized 4.4%, 24.9%, and 25.0% of reactive yellow K-RN respectively, indicating that there is a mutual promotion effect among the individual systems. The electro-magnetic-ozone system (E+M+O3) achieved the highest mineralization rate of reactive yellow K-RN (36.8%) within 180 min, which is greater than the other 5 control systems, indicating that this system has certain potential value for practical applications.

[0069] 2.6 Detection of oxygen free radicals in different systems

[0070] The electron spin resonance (EPR) technique was used to detect the generation of hydroxyl radicals (·OH), singlet oxygen (1O2), and superoxide anion radicals (·O2 - ) in the ozone and activated systems. The results are as Figure 7 .

[0071] As can be seen from Figure 7 , in the electro-magnetic-ozone system (E+M+O3), the characteristic peak intensities of 1 O2 and ·OH are much higher than those in the O3+E system and the O3+M system, indicating that adding a magnetic field to the E+O3 system or adding electrocatalysis to the O3+M system will enhance the activation process of O3 and increase the 1 amounts of O2 and ·OH in the reaction, enabling more free radicals to participate in the reaction process.

[0072] 2.7 Degradation effects of wastewater with different water qualities in the electro-magnetic-ozone system (E+M+O3)

[0073] Figure 8 Taking the high-salt printing and dyeing wastewater stock solution from Shandong Ruyi Textile as the water sample, the degradation effects of the electro-magnetic-ozone system (E+M+O3) at different times (pH adjusted to 9) were studied. Without changing the properties and parameters of the original water sample, the water sample degradation reached the expected effect after 9 hours, being at the leading level in the industry.

[0074] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wastewater treatment method for synergistically activating ozone by magnetic field and electricity, characterized in that, It includes the following steps: (1) Place the wastewater in a closed container and adjust the pH value to obtain a reaction solution; (2) Introduce ozone gas into the reaction solution and apply electricity to carry out an electrochemical activation reaction; (3) While carrying out the electrochemical activation reaction on the reaction solution in step (2), instantaneously magnetize the reaction solution with a magnetic field; (4) The reaction solution after instantaneous magnetization by the magnetic field is circulated through steps (2) to (3) until the wastewater meets the standard requirements.

2. The wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 1, characterized in that, In step (1), the pH value of the wastewater is adjusted to 8 - 10.

3. The wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 1, characterized in that, In step (2), ozone gas is introduced into the reaction solution, and the introduction amount is 0.4 - 0.5 L / min.

4. The wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 3, wherein The electrochemically activation reaction described in step (2) is carried out by a constant current method with a current density of 3.33 mA / cm 2 .

5. A wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 1, characterized in that, In step (2), stirring is carried out during the electrochemical activation reaction, the stirring rate is 500 - 1000 rpm, and the reaction temperature is 10 - 20 °C.

6. The wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 1, characterized in that, In step (3), the instantaneous magnetization of the magnetic field is carried out through an external magnetic field or an electromagnetic field arranged inside / outside the closed container; The external magnetic field is a long-term magnetic field; the electromagnetic field is an instantaneous magnetic field.

7. A wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 1, characterized in that, The intensity of the magnetic field ≥ 0.8 T.

8. A wastewater treatment method for synergistically activating ozone by magnetic field and electricity according to claim 1, characterized in that, In step (3), the magnetization time of the reaction solution by the magnetic field is 0.006 s.

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