Advanced wastewater treatment method based on surface catalytic ozonation

Abstract

The invention belongs to the field of wastewater treatment, and provides an advanced wastewater treatment method based on surface catalytic ozonation, which comprises the following steps: continuously or in batches adding wastewater into a closed wastewater treatment device from the upper part of the closed wastewater treatment device, and adding a catalyst into the wastewater, the method comprises the following steps: continuously introducing ozone-containing gas into wastewater from the lower part of a closed wastewater treatment device for wastewater treatment, collecting ozone tail gas generated in the wastewater treatment process at the top of the closed wastewater treatment device, discharging the ozone tail gas after harmless treatment, and continuously discharging the treated wastewater in batches; in the wastewater treatment process, the catalyst catalyzes ozone to generate surface hydroxyl free radicals and surface atomic oxygen which are adsorbed on the surface of the catalyst to degrade organic pollutants in wastewater; the catalyst is a nanoscale copper-cobalt bimetallic catalyst. The anti-interference capability of the wastewater treatment method on a water body matrix can be improved, the pollutant degradation efficiency can be improved, and the actual complex wastewater treatment requirement can be better met.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater treatment and relates to a method for advanced treatment of wastewater based on surface catalytic ozonation. Background Art

[0002] The up-to-standard discharge and recycling of industrial wastewater are key links in ensuring water quality safety and ecological health and promoting the utilization of sewage resources. The refractory organic compounds contained in industrial wastewater, such as pharmaceuticals and personal care products, endocrine disruptors, synthetic chemicals, etc., are characterized by complex composition, stable structure and long half-life, and are difficult to be effectively removed by traditional physical and chemical and biochemical treatment technologies, which is one of the key challenges faced by the current industrial wastewater in achieving up-to-standard discharge and recycling. In recent years, the advanced treatment technology based on the advanced oxidation process has become an important means for treating biologically refractory and toxic organic pollutants due to its advantages such as high efficiency and low cost, and has been widely applied to the actual wastewater treatment.

[0003] The advanced oxidation technology is a typical environmental treatment technology for removing refractory organic pollutants, mainly using transition metals as catalysts, and generating highly oxidizing free radicals through the activation of hydrogen peroxide (H 2 O 2 ), persulfate (PMS / PDS), permanganate (MnO 4- ), ozone (O 3 ), peracetic acid (PAA) and other oxidants to convert organic pollutants into harmless or less harmful chemical substances. Among them, the ozonation catalytic oxidation technology has become one of the commonly used wastewater advanced treatment technologies in current actual projects due to its advantages such as high oxidation efficiency, in-situ generation of ozone without transportation risk, and almost no sludge production.

[0004] The traditional heterogeneous catalytic ozonation technology mainly relies on the catalyst to catalyze ozone to generate free hydroxyl radicals to achieve the efficient removal of pollutants. The free hydroxyl radical has a relatively high redox potential, but its oxidation reaction is non-selective. In addition to reacting with the target pollutants, it is also easy to react with the organic matter and inorganic anions coexisting in the water body (such as humic acid, chloride ions, etc.), thereby significantly affecting the effective utilization of the oxidant, reducing the oxidation efficiency and increasing the operating cost.

[0005] In recent years, researchers at home and abroad have successively discovered that in addition to free radical species, surface-adsorbed reactive oxygen species, such as surface hydroxyl radicals and surface atomic oxygen, also exist in some heterogeneous advanced oxidation systems. Compared with bulk free radical species, surface-adsorbed reactive oxygen species can maintain higher oxidation ability and longer survival life. Most of the oxidation reactions mediated by them occur on the catalyst surface, so they have strong anti-interference ability against co-existing matrixes in water bodies. However, most of the reactive oxygen species generated by current heterogeneous catalysts during the catalytic ozonation reaction process are free radical species. The ozonation process is still an oxidation process dominated by free radical species. There is a lack of a method to construct an ozonation process mediated by surface-adsorbed reactive oxygen species, which limits the development of the ozonation catalytic oxidation technology mediated by surface reactive oxygen species and its application and popularization in the efficient removal of refractory organic pollutants. Therefore, constructing an ozonation process mediated by surface-adsorbed reactive oxygen species and achieving the advanced treatment of wastewater based on this will be of great significance for improving the anti-interference ability of wastewater treatment methods and the treatment efficiency of water body environmental pollution, etc. Summary of the Invention

[0006] Aiming at the problem that the existing ozonation catalytic oxidation water treatment process is dominated by free radical species, and the oxidation process is easily interfered by the co-existing matrix in the water body, resulting in the reduction of the effective utilization rate of the oxidant and the oxidation efficiency, the present invention provides an advanced wastewater treatment method based on surface catalytic ozonation. By constructing an ozonation process mediated by surface-adsorbed reactive oxygen species, the anti-interference ability of the wastewater treatment method against the water body matrix is improved and the pollutant degradation efficiency is increased, so as to better meet the needs of organic pollutant degradation in the actual complex wastewater system.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The advanced wastewater treatment method based on surface catalytic ozonation includes the following steps:

[0009] The wastewater is continuously or batchwise added into a closed wastewater treatment device from the upper part of the closed wastewater treatment device. A catalyst is added to the wastewater. A gas containing ozone is continuously introduced into the wastewater from the lower part of the closed wastewater treatment device for wastewater treatment. The ozone tail gas generated during the wastewater treatment process is collected at the top of the closed wastewater treatment device and discharged after harmless treatment. The treated wastewater is continuously or batchwise discharged; during the wastewater treatment process, the catalyst catalyzes ozone to generate surface hydroxyl radicals and surface atomic oxygen adsorbed on the catalyst surface to degrade organic pollutants in the wastewater; the catalyst is a nanoscale copper-cobalt bimetallic catalyst, and this catalyst is composed of CuO and Co 3 O 4 and CuO and Co 3 O 4 form a heterostructure.

[0010] In the technical solution of the above wastewater advanced treatment method, the preparation method of the catalyst is as follows: A copper source and ZIF-67 are added to a solvent according to a mass percentage of (40% - 60%):(40% - 60%), and react fully at 120 - 240 °C. After solid-liquid separation, the obtained solid phase is washed with the solvent, and then crushed to obtain a reaction precursor. The reaction precursor is calcined at 350 - 550 °C for 1 - 5 h, and the unreacted substances in the calcined product are removed by washing, dried, and crushed to obtain the catalyst.

[0011] In the technical solution of the above wastewater advanced treatment method, when preparing the catalyst, it is preferably controlled that the reaction time of the copper source and ZIF-67 at 120 - 240 °C is 4 - 12 h. When preparing the catalyst, the solvent used is at least one of water, methanol, ethanol, and N,N-dimethylformamide. When preparing the catalyst, the heating method used can be oil bath heating, hydrothermal reaction in a reaction kettle, microwave heating, etc.

[0012] In the technical solution of the above wastewater advanced treatment method, when preparing the catalyst, the copper source is a water-soluble divalent copper salt, and the water-soluble divalent copper includes at least one of copper nitrate, copper chloride, copper acetate, and copper sulfate.

[0013] In the technical solution of the above wastewater advanced treatment method, when preparing the catalyst, the reaction precursor is calcined in an atmosphere of air, oxygen, or a mixed gas of air and oxygen.

[0014] In the technical solution of the above wastewater advanced treatment method, when preparing the catalyst, after the reaction precursor is calcined at 350 - 550 °C for 1 - 5 h, when washing to remove the unreacted substances in the calcined product, the washing methods used include one or more of washing methods such as water washing, alcohol washing, and acid washing. When alcohol washing, the alcohol solution used includes at least one of methanol, ethanol, etc. When acid washing, the acid solvent used includes at least one of dilute hydrochloric acid, dilute sulfuric acid, and dilute nitric acid.

[0015] In the technical solution of the above wastewater advanced treatment method, the preparation method of ZIF-67 is as follows: A cobalt source and 2-methylimidazole are fully mixed in a solvent according to a mass percentage of (37% - 47%):(53% - 63%), and after reacting at 20 - 50 °C for 0.5 - 4 h, they are left to stand and precipitate at room temperature for 24 - 48 h to obtain ZIF-67. The cobalt source is a water-soluble divalent cobalt salt, and the water-soluble divalent cobalt salt includes at least one of cobalt nitrate, cobalt chloride, cobalt sulfate, and cobalt acetate. When preparing ZIF-67, the solvent used is at least one of water, methanol, ethanol, and N,N-dimethylformamide.

[0016] In the technical solution of the above-mentioned advanced wastewater treatment method, the size of the catalyst is in the nanometer scale, usually referring to the size of the catalyst being less than 1 micron. During the wastewater treatment process, the catalyst with a nanometer-scale size can be fully dispersed in the wastewater and come into full contact with the pollutants in the wastewater under the action of the water flow and the gas flow containing ozone, without the need to apply dispersion means such as stirring during the wastewater treatment process to promote the full contact between the catalyst and the pollutants in the wastewater.

[0017] In the technical solution of the above-mentioned advanced wastewater treatment method, the catalyst is a copper-cobalt bimetallic catalyst with uniformly dispersed copper and cobalt and the original morphology of ZIF-67 constructed using the unique dodecahedral morphology structure feature of ZIF-67. ZIF-67 has characteristics such as a large specific surface area, uniform pore size, and uniform pore distribution, which can enhance the adsorption of copper ions, promote the more uniform distribution of cobalt and copper sites in the copper-cobalt bimetallic catalyst formed after calcination, thus facilitating an increase in the number of Lewis acid sites on the catalyst surface and strengthening the adsorption and decomposition of ozone by cobalt and copper sites. At the same time, CuO and Co 3 O 4 in the catalyst form a heterostructure, and the electron transfer between CuO and Co 3 O 4 can improve the redox performance and electron transfer performance of the catalyst, and further enhance the activation performance of the catalyst for ozone.

[0018] In the technical solution of the above-mentioned advanced wastewater treatment method, the dosage of the catalyst added to the wastewater is related to the water quality of the wastewater (such as the types of pollutants and pollutant concentrations in the wastewater). In practical applications, after the water quality of the wastewater to be treated is determined, the dosage of the catalyst can be determined through experiments. Usually, the dosage of the catalyst added to the wastewater can be controlled at 0.2 - 10 g / L.

[0019] In the technical solution of the above-mentioned advanced wastewater treatment method, the amount of the gas containing ozone continuously introduced into the wastewater in the closed wastewater treatment device is related to the water quality of the wastewater (such as the types of pollutants and pollutant concentrations in the wastewater). In practical applications, after the water quality of the wastewater to be treated is determined, the ozone dosage in the wastewater can be determined through experiments. Usually, the gas containing ozone can be introduced into the wastewater in the closed wastewater treatment device at a rate of 0.4 - 5 mmol of ozone per liter of wastewater per minute. The gas containing ozone is air containing ozone or oxygen containing ozone.

[0020] The present invention has confirmed through experiments that when treating wastewater with a pH value of 3 - 11 using the method of the present invention, the organic pollutants in the wastewater all have a high mineralization rate. Therefore, in the technical solution of the above-mentioned advanced wastewater treatment method, the pH value of the wastewater can usually be controlled at 3 - 11.

[0021] In the technical solution of the above-mentioned advanced wastewater treatment method, the wastewater treatment time is determined according to actual application requirements. For example, it can be determined based on factors such as the removal degree of target pollutants and the change degree of a certain water quality index. Specifically, the wastewater treatment time is related to factors such as the water quality of the wastewater, the dosage of the catalyst, and the dosage of ozone. Usually, when adopting the treatment method of continuously introducing wastewater and continuously discharging the treated wastewater, the hydraulic retention time of the wastewater in the closed wastewater treatment is controlled to be 30 - 120 min; when adopting the treatment method of batch introducing wastewater and batch discharging the treated wastewater, the wastewater treatment time is controlled to be 20 - 180 min.

[0022] In the technical solution of the above-mentioned advanced wastewater treatment method, during the wastewater treatment process, usually controlling the wastewater temperature at room temperature (such as 5 - 40 °C, 10 - 35 °C) is sufficient, and generally there is no need to specifically control the temperature of the wastewater.

[0023] In the technical solution of the above-mentioned advanced wastewater treatment method, the closed wastewater treatment device can be the common device used in the prior art for wastewater treatment using the ozone catalytic oxidation technology. For example, a bubble column reactor, a fluidized bed reactor, a tubular reactor, etc.

[0024] In the technical solution of the above-mentioned advanced wastewater treatment method, the method for harmless treatment of the ozone tail gas generated during the wastewater treatment process can refer to the existing ozone tail gas treatment method and use the existing ozone tail gas treatment device for harmless treatment.

[0025] In the technical solution of the above-mentioned advanced wastewater treatment method, the types of pollutants contained in the wastewater include pharmaceutical pollutants, industrial chemicals, organic nitrogen pollutants, etc. The wastewater can be the secondary effluent of industrial wastewater, such as the secondary effluent of chemical wastewater, the secondary effluent of pharmaceutical wastewater, etc.

[0026] The present invention has been verified through experiments that after the catalyst in the technical solution of the above-mentioned advanced wastewater treatment method is recycled 5 times, when it catalyzes the ozone oxidation degradation of sulfamethoxazole, the mineralization rate of sulfamethoxazole only decreases by 5% compared with when the catalyst is used for the first time, and it is still 30% higher than the mineralization rate of sulfamethoxazole using a simple ozone system. This shows that the catalyst adopted by the present invention has excellent recyclability in catalyzing the ozone oxidation degradation of organic pollutants and can be recycled multiple times in actual wastewater treatment to reduce the wastewater treatment cost. The number of recycling times of the catalyst is determined according to actual application requirements. For example, the catalyst can be recycled 5 - 10 times.

[0027] The present invention is verified by experiments that when the wastewater contains inorganic anions such as chloride ions and sulfate ions which are prone to react with free hydroxyl radicals, the degradation ability of the method of the present invention for the pollutants in the wastewater is not affected by the coexisting inorganic anions. For example, when the concentration of coexisting chloride ions in the wastewater is more than 600 times that of the target pollutant sulfamethoxazole, the mineralization ability of the method of the present invention for sulfamethoxazole is not adversely affected. Therefore, the method of the present invention can be used to treat wastewater containing matrixes such as inorganic anions and organic acids, and can meet the requirements for the degradation of organic pollutants under complex water body matrixes.

[0028] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0029] 1. The present invention provides a method for advanced treatment of wastewater based on surface catalytic ozonation. The method is based on a nano-scale copper-cobalt bimetallic catalyst containing a CuO and Co 3 O 4 heterostructure, and successfully constructs an ozonation process mediated by surface-adsorbed reactive oxygen species. During the process of treating wastewater by the method of the present invention, the catalyst catalyzes ozone to generate surface hydroxyl radicals and surface atomic oxygen adsorbed on the catalyst surface to degrade organic pollutants in the wastewater. Since the reactive oxygen species for degrading organic pollutants generated by the catalyst catalyzing ozone during the wastewater treatment process of the present invention are adsorbed on the catalyst surface, compared with free reactive oxygen species, the surface-adsorbed reactive oxygen species can maintain higher oxidation ability and longer survival life, and can solve the problem that the oxidation process in the existing ozonation catalytic oxidation water treatment process dominated by free radical species is easily affected by the coexisting matrix in the water body, which is beneficial to improving the effective utilization rate and oxidation efficiency of the oxidant and reducing the wastewater treatment cost, and can better meet the requirements for the degradation of organic pollutants in the actual complex wastewater system.

[0030] 2. The present invention is verified by experiments that the method of the present invention has excellent effects in degrading and deeply mineralizing refractory pollutants in wastewater. For example, when the method of the present invention is used and the catalyst is added and ozone is continuously introduced for reaction for 20 min, the complete degradation of 0.5 mmol / L oxalic acid can be achieved, but when ozone is simply introduced for reaction for 30 min, the removal rate of oxalic acid with the same concentration is only 6%. Another example is that when the method of the present invention is used and the catalyst is added and ozone is continuously introduced for reaction for 60 min, the mineralization rate of 20 mg / L sulfamethoxazole reaches 60%, and there is a significant improvement in the mineralization rate of sulfamethoxazole compared with the case of simply introducing ozone for reaction for 60 min.

[0031] 3. The present invention has been experimentally verified that the ozone oxidation process mediated by surface-adsorbed reactive oxygen species constructed by the method of the present invention degrades organic pollutants by using surface-adsorbed reactive oxygen species including surface hydroxyl radicals and surface atomic oxygen, significantly improving the anti-interference performance of the method against water matrix. Under the condition of coexistence of 50 mmol / L chloride ions (more than 600 times the pollutant concentration), the mineralization performance of sulfamethoxazole by the method of the present invention is not adversely affected, which can meet the treatment requirements of organic pollutants under complex water matrix and effectively improve the treatment efficiency of water environmental pollution.

[0032] 4. The present invention has been experimentally verified that the catalyst of the present invention has excellent recycling performance. When catalyzing the degradation of sulfamethoxazole by ozone, after the catalyst is recycled 5 times, the mineralization rate of sulfamethoxazole only decreases by 5% compared with the first use of the catalyst, and it is still 30% higher than the mineralization rate of sulfamethoxazole in the simple ozone system. At the same time, the method of the present invention has good mineralization ability for wastewater with a pH value of 3 - 11. These two characteristics are very beneficial for the application of the method of the present invention in actual engineering, which can not only reduce the wastewater treatment cost, but also show excellent treatment ability for wastewater in a wide pH value range.

[0033] 5. The present invention has been experimentally verified that when treating the secondary effluent of chemical industrial wastewater by the method of the present invention, the removal rate of COD is 70% at 120 min of reaction, which is about 55% higher than that of only continuously introducing ozone for reaction; when treating the secondary effluent of pharmaceutical wastewater by the method of the present invention, the removal rate of COD is 90% at 120 min of reaction, which is about 35% higher than that of only continuously introducing ozone for reaction. This shows that the method of the present invention also has excellent treatment ability for actual wastewater and has potential application value in actual wastewater treatment. Description of the Drawings

[0034] Figure 1 It is the X-ray diffraction pattern of the catalyst prepared in Example 1.

[0035] Figure 2 It is the transmission electron microscope and high-resolution transmission electron microscope images of the catalyst prepared in Example 1.

[0036] Figure 3 It is the test result of the oxalic acid removal rate in Example 1.

[0037] Figure 4 It is the test result of the quenching experiment in Example 1.

[0038] Figure 5 It is the test result of the sulfamethoxazole mineralization rate in Example 2.

[0039] Figure 6 It is the influence of coexisting chloride ions on the mineralization rate of sulfamethoxazole in Example 2.

[0040] Figure 7 It is the test result of the mineralization rate of sulfamethoxazole during the recycling process of the catalyst in Example 2.

[0041] Figure 8 It is the test result of the mineralization rate of sulfamethoxazole in simulated wastewater with different pH values in Example 2.

[0042] Figure 9 It is the variation of the chemical oxygen demand of the secondary effluent of chemical industrial wastewater with the treatment time in Example 10.

[0043] Figure 10 It is the variation of the chemical oxygen demand of the secondary effluent of pharmaceutical wastewater with the treatment time in Example 11. Detailed implementation manners

[0044] The following further illustrates the wastewater advanced treatment method based on surface catalytic ozonation according to the present invention through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art make some non-essential improvements and adjustments to the present invention according to the above invention content for specific implementation, which still fall within the protection scope of the invention.

[0045] Example 1

[0046] In this example, the copper-cobalt bimetallic catalyst is prepared as follows:

[0047] (1) Cobalt nitrate hexahydrate and 2-methylimidazole are added to anhydrous methanol, and the mass percentage of cobalt nitrate hexahydrate to 2-methylimidazole is controlled at 47%:53% (that is, cobalt nitrate hexahydrate and 2-methylimidazole account for 47% and 53% of the total mass of the two respectively), and they are fully stirred and mixed. Then, they are vigorously stirred at room temperature for 0.5 h, and then left to stand at room temperature for 24 h to obtain ZIF-67.

[0048] (2) Copper nitrate trihydrate and ZIF-67 are added to anhydrous ethanol, and the mass percentage of copper nitrate trihydrate to ZIF-67 is controlled at 50%:50% (that is, copper nitrate trihydrate and ZIF-67 account for 50% and 50% of the total mass of the two respectively). Then, it is transferred to a stainless steel autoclave with a Teflon lining and reacted at 120 °C for 4 h. After filtration, the obtained solid phase is washed with ethanol, dried, and ground to obtain the reaction precursor.

[0049] (3) Place the reaction precursor in a muffle furnace and calcine it in an air atmosphere at 350 °C for 2 h. Wash the obtained calcined product with water to remove unreacted substances, and grind it to obtain a copper-cobalt bimetallic catalyst with a nanoscale particle size.

[0050] Figure 1 is the X-ray diffraction (XRD) pattern of the catalyst prepared in this example. It can be seen from the figure that the catalyst consists of CuO and Co 3 O 4 ; Figure 2 Figures (A) and (B) are the transmission electron microscope image and high-resolution transmission electron microscope image of the catalyst prepared in this example, respectively. It can be determined from the figure that CuO and Co 3 O 4 in the catalyst form a heterostructure.

[0051] Next, investigate the ability of the catalyst prepared in this example to catalyze the ozonation degradation of pollutants and examine the active species generated during the degradation of pollutants through a quenching experiment.

[0052] (1) Investigate the degradation effect of pollutants with or without the addition of a catalyst

[0053] Use oxalic acid (OA) as a model pollutant for the advanced treatment of wastewater. Dissolve OA in water to form an OA solution with a concentration of 0.5 mmol / L, and use this OA solution as the simulated wastewater.

[0054] Add the simulated wastewater to the bubble column reactor in batches from the upper part of the bubble column reactor. Add the catalyst to the simulated wastewater at a dosage of 0.4 g / L. After adding the catalyst, adsorb and treat it for 10 min. Then, continuously introduce ozone-containing oxygen from the bottom of the bubble column reactor into the simulated wastewater for wastewater treatment at a rate of 0.83 mmol of ozone per liter of wastewater per minute. Collect the ozone tail gas generated during the wastewater treatment at the top of the bubble column reactor and discharge it after harmless treatment. Discharge the treated wastewater from the bubble column reactor in batches. At 0, 2, 5, 10, 20, and 30 min after introducing ozone-containing oxygen for reaction, take samples, filter them with a 0.22 μm filter membrane, measure the concentration of OA, and calculate the OA removal rate. The results are as Figure 3 shown. It can be seen from Figure 3 that the catalyst has OA adsorption activity, adsorbs and removes 18% of OA within 10 min, and can achieve 100% degradation of OA when reacting with ozone-containing oxygen for 20 min.

[0055] At the same time, set up a control group for the single-ozone reaction system. The operation of the control group is basically the same as the above operation in this step, except that no catalyst is added. The results are as Figure 3 shown. It can be seen from Figure 3It can be seen that after the adsorption is completed and the reaction continues for 30 min, the separate ozone reaction system can only remove 6% of OA.

[0056] (2) Quenching experiment

[0057] tert-Butanol, methanol, and dimethyl sulfoxide (DMSO) were used as quenchers for free hydroxyl radicals, free and surface-adsorbed hydroxyl radicals, and surface hydroxyl radicals and surface atomic oxygen, respectively.

[0058] OA was dissolved in water to form an OA solution with a concentration of 0.5 mmol / L, which was used as the simulated wastewater. Three experimental groups and a blank control group (without adding a quencher) were set up. In the three experimental groups, tert-butanol was added to the simulated wastewater to a concentration of 200 mmol / L, methanol was added to a concentration of 200 mmol / L, and DMSO was added to a concentration of 200 mmol / L. Specifically as follows:

[0059] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The corresponding quenchers (the blank control group did not add a quencher) and the catalyst were added to each simulated wastewater. After adding the catalyst, the adsorption treatment was carried out for 10 min. Then, oxygen containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 0.83 mmol ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment, and the treated wastewater was batch-discharged from the bubble column reactor. The dosage of the catalyst was controlled at 0.4 g / L. At 0, 2, 5, 10, 20, and 30 min when reacting with oxygen containing ozone, samples were taken and filtered through a 0.22 μm filter membrane to test the concentration of OA, and the OA removal rate was calculated. The results are as Figure 4 shown.

[0060] It can be Figure 4 seen that the OA removal rate in the experimental group with DMSO added as the quencher was the lowest, and the degradation of OA in the experimental group with methanol added as the quencher was also inhibited to a certain extent. Since DMSO is a quencher for surface atomic oxygen and surface hydroxyl radicals, and methanol is a quencher for surface hydroxyl radicals and free hydroxyl radicals, and the OA removal rate in the experimental group with tert-butanol added as the quencher was the same as that in the blank control group, this indicates that free hydroxyl radicals do not exist among the main active species generated by the catalyst during the catalytic ozonation degradation of OA, and the main ones are surface atomic oxygen and surface hydroxyl radicals, that is, the catalyst prepared based on this example can successfully construct a surface catalytic ozonation process.

[0061] Example 2

[0062] In this example, the catalyst prepared in Example 1 was used to catalyze the ozonation degradation of wastewater containing organic pollutants, and the steps were as follows:

[0063] (1) Sulfamethoxazole (SMX) degradation experiment

[0064] SMX was dissolved in water to form an SMX solution with a concentration of 20 mg / L, and its pH value was between 6 and 7. This SMX solution was used as the simulated wastewater.

[0065] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The catalyst was added to the simulated wastewater at a dosage of 0.4 g / L. Then, ozone-containing oxygen was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 0.83 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment process was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. At 0, 15, 30, and 60 min of reacting with ozone-containing oxygen, samples were taken and filtered through a 0.22 μm filter membrane to measure the total organic carbon (TOC) concentration of the simulated wastewater, and the SMX mineralization rate was calculated. The results are as Figure 5 shown.

[0066] Meanwhile, a control group of a single ozone reaction system was set up. The operation of the control group was basically the same as the above operation of this step, except that no catalyst was added. The results are as Figure 5 shown.

[0067] As can be Figure 5 seen, in the single ozone oxidation system of the control group, after reacting for 60 min, the mineralization rate of SMX was only 23%, while in the method of the present invention, after reacting for 60 min, the mineralization rate of SMX reached 60%. This shows that the surface catalytic ozonation process constructed by the method of the present invention under the conditions of adding a catalyst and introducing ozone can effectively improve the mineralization ability of pollutants.

[0068] (2) Anti-interference performance experiment

[0069] Chloride ions (Cl - ) are inorganic anions commonly present in actual wastewater matrices, and their concentrations are often 1-2 orders of magnitude higher than the target pollutant concentration.

[0070] Two experimental groups and a blank control group were set up. The wastewater sample of the first experimental group was prepared by adding 5 mmol / L of chloride ions (5 mM Cl - ) to the SMX solution, and the wastewater sample of the second experimental group was prepared by adding 50 mmol / L of chloride ions (50 mM Cl -) The wastewater sample of the blank control group is the SMX solution to evaluate the anti-interference performance of the method described in the present invention.

[0071] The wastewater samples of the above two experimental groups and the blank control group were respectively added batchwise into the bubble column reactor from the upper part of the bubble column reactor. The catalyst was added to the wastewater samples at a dosage of 0.4 g / L. Then, oxygen containing ozone was continuously introduced into the wastewater samples from the bottom of the bubble column reactor at a rate of 0.83 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was discharged batchwise from the bubble column reactor. At 0, 15, 30, and 60 min after introducing oxygen containing ozone for reaction, samples were taken and filtered through a 0.22 μm filter membrane to measure the TOC value of the water samples and calculate the SMX mineralization rate. The results are as Figure 6 shown.

[0072] Meanwhile, a simple ozone control group was set up. The operation of the simple ozone control group was basically the same as that of the blank control group, except that the catalyst was not added. The experimental results of the simple ozone control group are also as Figure 6 shown.

[0073] It can be seen from Figure 6 that when the wastewater contains different concentrations of chloride ions, the SMX mineralization rates of the two experimental groups are the same as those of the blank control group. The SMX mineralization rate is not affected by the coexisting chloride ions. At the same time, compared with the simple ozone control group, both the two experimental groups and the blank control group have higher SMX mineralization rates, indicating that the method of the present invention has strong anti-interference ability.

[0074] (3) Catalyst recycling experimental performance experiment

[0075] ① Dissolve SMX in water to form an SMX solution with a concentration of 20 mg / L, and use this SMX solution as the simulated wastewater.

[0076] The simulated wastewater was added batchwise into the bubble column reactor from the upper part of the bubble column reactor. The catalyst was added to the simulated wastewater at a dosage of 0.4 g / L. Then, oxygen containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 0.83 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was discharged batchwise from the bubble column reactor. After introducing oxygen containing ozone for reaction for 60 min, samples were taken and filtered through a 0.22 μm filter membrane to measure the TOC of the simulated wastewater, calculate the SMX mineralization rate, and filter and separate the catalyst from the discharged treated wastewater.

[0077] ②Put the separated catalyst into fresh simulated wastewater and repeat the wastewater treatment operation in step ①.

[0078] ③Repeat the operations in steps ① and ② until the catalyst is recycled 5 times.

[0079] The change of SMX mineralization rate during the recycling process is as Figure 7 shown. It can be seen from Figure 7 that after the catalyst prepared in Example 1 is recycled 5 times, the SMX mineralization rate only decreases by 5%. This mineralization rate is still 30% higher than that of the SMX mineralization rate in the pure ozone system. The above experimental results show that the catalyst described in the present invention has good stability and recyclability. Recycling the catalyst during the wastewater treatment process is beneficial to reducing the cost of wastewater treatment.

[0080] (4) Applicability experiment on the pH value of wastewater

[0081] Dissolve SMX in water to form an SMX solution with a concentration of 20 mg / L, and adjust the pH value of the SMX solution to 3, 6, 7, 9, and 11 with HNO 3 and NaOH solutions respectively to obtain a series of simulated wastewaters with different pH values.

[0082] Batch add the simulated wastewaters with different pH values into the bubble column reactor from the upper part of the bubble column reactor. Add the catalyst to the simulated wastewater at a dosage of 0.4 g / L, and then continuously introduce the ozone-containing oxygen into the simulated wastewater from the bottom of the bubble column reactor at a rate of 0.83 mmol of ozone per liter of wastewater per minute for wastewater treatment. Collect the ozone tail gas generated during the wastewater treatment at the top of the bubble column reactor and discharge it after harmless treatment, and batch discharge the treated wastewater from the bubble column reactor. After reacting with the ozone-containing oxygen for 60 min, take samples and filter them with a 0.22 μm filter membrane, measure the TOC of the simulated wastewater, and calculate the SMX mineralization rate. The results are as Figure 8 shown. At the same time, set up a pure ozone control group. The operation of the pure ozone control group is basically the same as the foregoing operation in this step, except that no catalyst is added. The experimental results of the pure ozone control group are also as Figure 8 shown.

[0083] It can be seen from Figure 8It can be seen that when the pH value of the simulated wastewater is 3-11, after reacting for 60 min by introducing ozone-containing oxygen and adding a catalyst, the mineralization rate of SMX reaches nearly 60%. Under the condition of the same wastewater pH value, when only introducing ozone-containing oxygen without adding a catalyst, the mineralization rate of SMX does not exceed 35%. This shows that the method of the present invention has a wide applicable range of wastewater pH value, and can avoid adjusting the wastewater pH value or reduce the consumption of acids and alkalis for adjusting the wastewater pH value in practical applications.

[0084] Example 3

[0085] In this example, a copper-cobalt bimetallic catalyst was prepared. The operation was basically the same as that in Example 1, except that in step (2), the mass percentage of copper nitrate trihydrate to ZIF-67 was controlled to be 60%:40% (that is, copper nitrate trihydrate and ZIF-67 accounted for 40% and 60% of their total mass, respectively).

[0086] Next, the ability of the catalyst prepared in this example to catalyze the degradation of pollutants by ozone oxidation was investigated, and the active species generated during the degradation of pollutants were investigated through a quenching experiment.

[0087] (1) Degradation effect on pollutants

[0088] OA was dissolved in water to form an OA solution with a concentration of 1 mmol / L, and this OA solution was used as the simulated wastewater.

[0089] The simulated wastewater was batch-added to the bubble column reactor from the upper part of the bubble column reactor. The catalyst was added to the simulated wastewater at a dosage of 0.4 g / L. Then, ozone-containing air was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 5 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment, and the treated wastewater was batch-discharged from the bubble column reactor. When reacting for 30 min by introducing ozone-containing air, a sample was taken and filtered through a 0.22 μm filter membrane to measure the concentration of OA, and the OA removal rate was calculated. The results showed that 100% degradation of OA could be achieved at 30 min of reaction.

[0090] (2) Quenching experiment

[0091] tert-Butanol, methanol, and DMSO were used as quenchers for free hydroxyl radicals, free hydroxyl radicals and surface-adsorbed hydroxyl radicals, surface hydroxyl radicals and surface atomic oxygen, respectively.

[0092] Dissolve OA in water to form an OA solution with a concentration of 1 mmol / L, and use this solution as the simulated wastewater. Set up three experimental groups and a blank control group (without adding quenching agent). In the three experimental groups, add tert-butanol to a concentration of 200 mmol / L, add methanol to a concentration of 200 mmol / L, and add DMSO to a concentration of 200 mmol / L respectively. Specifically as follows:

[0093] Add the simulated wastewater batchwise from the upper part of the bubble column reactor to the bubble column reactor. Add the corresponding quenching agent (the blank control group does not add the quenching agent) and catalyst to each simulated wastewater. Then, continuously introduce the ozone-containing air from the bottom of the bubble column reactor into the simulated wastewater for wastewater treatment at a rate of 5 mmol of ozone per liter of wastewater per minute. Collect the ozone tail gas generated during the wastewater treatment at the top of the bubble column reactor and discharge it after harmless treatment. Discharge the treated wastewater batchwise from the bubble column reactor. Control the dosage of the catalyst to be 0.4 g / L. When reacting with the ozone-containing air for 30 min, take samples and filter them with a 0.22 μm filter membrane, test the concentration of OA, and calculate the OA removal rate.

[0094] The test results show that tert-butanol has no inhibitory effect on the degradation of OA, the addition of methanol significantly inhibits the degradation of OA, and the addition of DMSO has the most obvious inhibitory effect on the degradation of OA. This indicates that when the catalyst of the present invention catalyzes the ozonation degradation of OA, free hydroxyl radicals do not exist in the main active species generated, and the main ones are surface atomic oxygen and surface hydroxyl radicals, that is, the catalyst prepared based on this example can successfully construct a surface catalytic ozonation process.

[0095] Example 4

[0096] In this example, use the catalyst prepared in Example 3 to catalyze the ozonation degradation of the simulated wastewater containing SMX. The steps are as follows:

[0097] Dissolve SMX in water to form an SMX solution with a concentration of 20 mg / L, and its pH value is between 6 and 7. Use this SMX solution as the simulated wastewater.

[0098] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The catalyst was added to the simulated wastewater at a dosage of 0.4 g / L. Then, air containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 2.5 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after being harmlessly treated. The treated wastewater was batch-discharged from the bubble column reactor. At 0, 15, 30, and 60 min of reacting with the ozone-containing air, samples were taken and filtered through a 0.22-μm filter membrane to measure the TOC concentration of the simulated wastewater and calculate the SMX mineralization rate. The results showed that the SMX mineralization rate reached 70% at 60 min of reaction.

[0099] Meanwhile, a control group with a separate ozone reaction system was set up. The operation of the control group was basically the same as the above operation in this step, except that the catalyst was not added. The results showed that for the separate ozone oxidation system, the SMX mineralization rate was only about 35% at 60 min of reaction.

[0100] Example 5

[0101] In this example, a copper-cobalt bimetallic catalyst was prepared. The operation was basically the same as that in Example 1, except that: in step (1), the mass percentage of cobalt nitrate hexahydrate to dimethylimidazole was controlled at 37%:63%, and in step (2), the mass percentage of copper nitrate trihydrate to ZIF-67 was controlled at 40%:60%.

[0102] Next, the ability of the catalyst prepared in this example to catalyze the ozonation degradation of pollutants was investigated, and the active species generated during the degradation of pollutants was investigated through a quenching experiment.

[0103] (1) Degradation effect on pollutants

[0104] OA was dissolved in water to form an OA solution with a concentration of 0.5 mmol / L, and this OA solution was used as the simulated wastewater.

[0105] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The catalyst was added to the simulated wastewater at a dosage of 2 g / L. Then, air containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 1.2 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after being harmlessly treated. The treated wastewater was batch-discharged from the bubble column reactor. At 20 min of reacting with the ozone-containing air, samples were taken and filtered through a 0.22-μm filter membrane to measure the concentration of OA and calculate the OA removal rate. The results showed that 100% degradation of OA could be achieved at 20 min of reaction.

[0106] (2) Quenching experiment

[0107] tert - Butanol, methanol, and DMSO were used as quenchers for free hydroxyl radicals, free hydroxyl radicals and surface - adsorbed hydroxyl radicals, and surface hydroxyl radicals and surface atomic oxygen, respectively.

[0108] OA was dissolved in water to form an OA solution with a concentration of 0.5 mmol / L, and this solution was used as the simulated wastewater. Three experimental groups and a blank control group (without adding quenchers) were set up. In the three experimental groups, tert - butanol was added to a concentration of 200 mmol / L, methanol was added to a concentration of 200 mmol / L, and DMSO was added to a concentration of 200 mmol / L, respectively. Specifically as follows:

[0109] The simulated wastewater was batch - added to the bubble - column reactor from the upper part. The corresponding quenchers (the blank control group did not add quenchers) and catalysts were added to each wastewater. Then, air containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble - column reactor at a rate of 1.2 mmol ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment process was collected at the top of the bubble - column reactor and discharged after harmless treatment. The treated wastewater was batch - discharged from the bubble - column reactor. The dosage of the catalyst was controlled at 2 g / L. When reacting with ozone - containing air for 30 min, samples were taken, filtered with a 0.22 - μm filter membrane, the concentration of OA was measured, and the OA removal rate was calculated.

[0110] The test results showed that tert - butanol had no inhibitory effect on the degradation of OA, the addition of methanol significantly inhibited the degradation of OA, and the addition of DMSO had the most obvious inhibitory effect on the degradation of OA. This indicated that when the catalyst catalyzed the ozonation degradation of OA, free hydroxyl radicals did not exist in the main active species generated, and the main ones were surface atomic oxygen and surface hydroxyl radicals. That is, the catalyst prepared based on this example could successfully construct a surface - catalytic ozonation process.

[0111] Example 6

[0112] In this example, the catalyst prepared in Example 3 was used to catalyze the ozonation degradation of simulated wastewater containing p - nitrophenol (PNP). The steps were as follows:

[0113] PNP was dissolved in water to form a PNP solution with a concentration of 50 mg / L, and this PNP solution was used as the simulated wastewater.

[0114] Simulated wastewater is added to the bubble tower reactor in batches from the top of the bubble tower reactor, and a catalyst is added to the simulated wastewater according to the dosage of 2g / L, and then the air containing ozone is continuously passed into the simulated wastewater from the bottom of the bubble tower reactor according to the amount of passing 0.56mmol ozone into each liter of wastewater per minute for wastewater treatment, and the ozone tail gas generated in the wastewater treatment process is collected at the top of the bubble tower reactor and discharged after harmless treatment, and the treated wastewater is discharged from the bubble tower reactor in batches. The dosage of the catalyst is controlled to be, when the air containing ozone is passed through and reacts for 60min, a 0.22μm filter membrane is used for sampling, and the TOC concentration of the simulated wastewater is tested, and the PNP mineralization rate is calculated. The results show that the PNP mineralization rate reaches 95% when the present embodiment reacts for 60min.

[0115] Example 7

[0116] In this embodiment, the copper-cobalt bimetallic catalyst is prepared by the following steps:

[0117] (1) Cobalt chloride hexahydrate and 2-methylimidazole are added to anhydrous methanol, and the mass percentage of cobalt chloride hexahydrate and 2-methylimidazole is controlled to be 37%:63% (i.e., cobalt chloride hexahydrate and 2-methylimidazole account for 37% and 63% of the total mass of the two, respectively). The mixture is fully stirred and then vigorously stirred at room temperature for 4 hours, and then allowed to stand at room temperature for 24 hours to obtain ZIF-67.

[0118] (2) Copper nitrate trihydrate and ZIF-67 are added to anhydrous ethanol, and the mass percentage of copper nitrate trihydrate and ZIF-67 is controlled to be 40%:60% (that is, copper nitrate trihydrate and ZIF-67 account for 40% and 60% of the total mass of the two, respectively), and then transferred to a Teflon-lined stainless steel autoclave, reacted at 240°C for 12 hours, filtered, and the resulting solid phase was washed with ethanol, dried, and ground to obtain a reaction precursor.

[0119] (3) placing the reaction precursor in a muffle furnace, calcining at 550° C. for 2 h in an air atmosphere, washing the calcined product with water to remove unreacted substances, and grinding to obtain a copper-cobalt bimetallic catalyst with a particle size in the nanometer range.

[0120] The ability of the catalyst prepared in this example to catalyze the oxidation of ozone to degrade pollutants is examined below, and the active species generated during the degradation of pollutants are examined through quenching experiments.

[0121] (1) Degradation effect on pollutants

[0122] OA was dissolved in water to form an OA solution with a concentration of 0.5 mmol / L, and the OA solution was used as simulated wastewater.

[0123] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The catalyst was added to the simulated wastewater at a dosage of 0.4 g / L. Then, air containing ozone was continuously introduced into the wastewater in the bubble column reactor from the bottom at a rate of 3 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. When the reaction with air containing ozone lasted for 30 min, a sample was taken and filtered through a 0.22-μm filter membrane to measure the concentration of OA and calculate the OA removal rate. The results showed that 100% degradation of OA could be achieved at 30 min of reaction.

[0124] (2) Quenching experiment

[0125] tert-Butanol, methanol, and DMSO were used as quenchers for free hydroxyl radicals, free hydroxyl radicals and surface-adsorbed hydroxyl radicals, surface hydroxyl radicals and surface atomic oxygen, respectively.

[0126] OA was dissolved in water to form an OA solution with a concentration of 0.5 mmol / L, which was used as the simulated wastewater. Three experimental groups and a blank control group (without adding a quencher) were set up. In the three experimental groups, tert-butanol was added to a concentration of 200 mmol / L, methanol was added to a concentration of 200 mmol / L, and DMSO was added to a concentration of 200 mmol / L, respectively. Specifically as follows:

[0127] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The corresponding quenchers (the blank control group did not add a quencher) and the catalyst were added to each simulated wastewater. Then, air containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 3 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. The dosage of the catalyst was controlled at 0.4 g / L. When the reaction with air containing ozone lasted for 30 min, a sample was taken and filtered through a 0.22-μm filter membrane to measure the concentration of OA and calculate the OA removal rate.

[0128] The test results showed that tert-butanol had no inhibitory effect on the degradation of OA, the addition of methanol significantly inhibited the degradation of OA, and the addition of DMSO had the most obvious inhibitory effect on the degradation of OA. This indicated that free hydroxyl radicals did not exist among the main active species generated when the catalyst catalyzed the ozonation degradation of OA, but mainly surface atomic oxygen and surface hydroxyl radicals.

[0129] Example 8

[0130] In this embodiment, the copper-cobalt bimetallic catalyst is prepared by the following steps:

[0131] (1) Cobalt nitrate hexahydrate and 2-methylimidazole are added to anhydrous methanol, and the mass percentage of cobalt nitrate hexahydrate and 2-methylimidazole is controlled to be 45%:55% (i.e., cobalt nitrate hexahydrate and 2-methylimidazole account for 45% and 55% of the total mass of the two, respectively). The mixture is fully stirred and mixed, and then vigorously stirred at room temperature for 30 minutes, and then allowed to stand at room temperature for 48 hours to obtain ZIF-67.

[0132] (2) Add copper acetate monohydrate and ZIF-67 to anhydrous ethanol, control the mass percentage of copper acetate monohydrate and ZIF-67 to be 45%:55% (i.e., copper acetate monohydrate and ZIF-67 account for 45% and 55% of the total mass of the two, respectively), and then transfer to a Teflon-lined stainless steel autoclave, react at 220°C for 12h, filter, wash the resulting solid phase with ethanol, dry, and grind to obtain a reaction precursor.

[0133] (3) placing the reaction precursor in a muffle furnace, calcining at 350° C. for 5 h in an air atmosphere, washing the calcined product with water to remove unreacted substances, and grinding to obtain a copper-cobalt bimetallic catalyst with a particle size at the nanometer level.

[0134] The ability of the catalyst prepared in this example to catalyze the oxidation of ozone to degrade pollutants is examined below, and the active species generated during the degradation of pollutants are examined through quenching experiments.

[0135] (1) Degradation effect on pollutants

[0136] OA was dissolved in water to form an OA solution with a concentration of 0.1 mmol / L, and the OA solution was used as simulated wastewater.

[0137] The simulated wastewater was added to the bubble tower reactor in batches from the upper part of the bubble tower reactor, and the catalyst was added to the simulated wastewater at a dosage of 0.4 g / L. After that, the ozone-containing air was continuously introduced into the simulated wastewater from the bottom of the bubble tower reactor at an amount of 0.42 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment process was collected at the top of the bubble tower reactor and discharged after harmless treatment. The treated wastewater was discharged from the bubble tower reactor in batches. When the ozone-containing air was introduced for 30 minutes, the sample was filtered with a 0.22 μm filter membrane, the concentration of OA was tested, and the OA removal rate was calculated. The results showed that 100% degradation of OA could be achieved at 30 minutes of reaction.

[0138] (2) Quenching experiment

[0139] tert-Butanol, methanol, and DMSO were used as quenchers for free hydroxyl radicals, free hydroxyl radicals and surface-adsorbed hydroxyl radicals, and surface hydroxyl radicals and surface atomic oxygen, respectively.

[0140] OA was dissolved in water to form an OA solution with a concentration of 0.1 mmol / L, and this solution was used as the simulated wastewater. Three experimental groups and a blank control group (without adding a quencher) were set up. In the three experimental groups, tert-butanol was added to a concentration of 200 mmol / L, methanol was added to a concentration of 200 mmol / L, and DMSO was added to a concentration of 200 mmol / L, respectively. Specifically as follows:

[0141] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The corresponding quencher (the blank control group did not add a quencher) and catalyst were added to each simulated wastewater. Then, air containing ozone was continuously introduced into the simulated wastewater from the bottom of the bubble column reactor at a rate of 0.42 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment process was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. The dosage of the catalyst was controlled at 0.4 g / L. When reacting with the ozone-containing air for 30 min, a sample was taken and filtered through a 0.22-μm filter membrane to measure the concentration of OA and calculate the OA removal rate.

[0142] The test results showed that tert-butanol had no inhibitory effect on the degradation of OA, the addition of methanol significantly inhibited the degradation of OA, and the addition of DMSO had the most obvious inhibitory effect on the degradation of OA. This indicated that when the catalyst catalyzed the ozonation degradation of OA, free hydroxyl radicals did not exist in the main active species generated, but mainly surface atomic oxygen and surface hydroxyl radicals.

[0143] Example 9

[0144] In this example, the catalyst prepared in Example 8 was used to catalyze the ozonation degradation of wastewater containing diclofenac, and the steps were as follows:

[0145] Diclofenac was dissolved in water to form a diclofenac solution with a concentration of 20 mg / L, and this diclofenac solution was used as the simulated wastewater.

[0146] The simulated wastewater was batch-added to the bubble column reactor from the upper part. The catalyst was added to the simulated wastewater at a dosage of 0.5 g / L. Then, air containing ozone was continuously introduced into the wastewater in the bubble column reactor from the bottom at a rate of 1.25 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. When the reaction with ozone-containing air lasted for 60 min, a sample was taken and filtered through a 0.22-μm filter membrane to measure the TOC concentration of the simulated wastewater, and the diclofenac mineralization rate was calculated. The results showed that in this example, when the reaction lasted for 60 min, the diclofenac mineralization rate reached 80%.

[0147] Example 10

[0148] In this example, the catalyst prepared in Example 1 was used to catalyze the ozonation of the secondary effluent of chemical industrial wastewater. The chemical oxygen demand (COD) concentration of the secondary effluent of chemical industrial wastewater (i.e., industrial tail water) was 170 mg / L, the pH value was 8.10, and the concentrations of chloride ions, nitrate ions, and sulfate ions were 1531 mg / L, 35 mg / L, and 1213 mg / L, respectively. The operation was as follows:

[0149] The industrial tail water was batch-added to the bubble column reactor from the upper part. The catalyst was added to the industrial tail water at a dosage of 0.4 g / L. Then, air containing ozone was continuously introduced into the industrial tail water in the bubble column reactor from the bottom at a rate of 1.25 mmol of ozone per liter of wastewater per minute for wastewater treatment. The ozone tail gas generated during the wastewater treatment was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. When the reaction with ozone-containing air lasted for 30, 60, 90, and 120 min, samples were taken and filtered through a 0.22-μm filter membrane to measure the COD concentration of the water samples, and the COD removal rate was calculated. The results were as Figure 9 shown.

[0150] Meanwhile, a control group with a separate ozone reaction system was set up. The operation of the control group was basically the same as the above operation in this step, except that the catalyst was not added. The results were also as Figure 9 shown.

[0151] It can be seen from Figure 9 this that when the reaction lasted for 120 min, the removal rate of COD in the industrial tail water by the method of the present invention was 70%, while in the control group when the reaction lasted for 120 min, the removal rate of COD in the industrial tail water was only 15%.

[0152] Example 11

[0153] In this embodiment, the catalyst prepared in Embodiment 1 was used to catalyze the ozonation treatment of the secondary effluent of pharmaceutical wastewater. The COD concentration of the secondary effluent of pharmaceutical wastewater was 256 mg / L, the pH value was 8.86, and the concentrations of chloride ions, nitrate ions, and sulfate ions were 4528 mg / L, 5 mg / L, and 2190 mg / L respectively. The operation was as follows:

[0154] The secondary effluent of pharmaceutical wastewater was batch-added to the bubble column reactor from the upper part of the bubble column reactor. The catalyst was added to the secondary effluent of pharmaceutical wastewater at a dosage of 0.5 g / L. Then, air containing ozone was continuously introduced into the secondary effluent of pharmaceutical wastewater from the bottom of the bubble column reactor for wastewater treatment at a rate of 1.9 mmol of ozone per liter of wastewater per minute. The ozone tail gas generated during the wastewater treatment process was collected at the top of the bubble column reactor and discharged after harmless treatment. The treated wastewater was batch-discharged from the bubble column reactor. When the air containing ozone was introduced for reaction for 30, 60, 90, and 120 min, samples were taken and filtered through a 0.22-μm filter membrane to measure the COD concentration of the water samples and calculate the COD removal rate. The results were as Figure 10 shown.

[0155] Meanwhile, a control group with a separate ozone reaction system was set up. The operation of the control group was basically the same as the above operation of this step, except that the catalyst was not added. The results were also as Figure 10 shown.

[0156] It can be seen from Figure 10 this that when the method of the present invention was used for reaction for 120 min, the COD removal rate of the secondary effluent of pharmaceutical wastewater was 90%, while in the control group when the reaction was carried out for 120 min, the COD removal rate of the secondary effluent of pharmaceutical wastewater was only 55%.

Claims

1. A wastewater deep treatment method based on surface catalytic ozone oxidation, characterized in that: The following steps are involved: Wastewater is continuously or batch-added into the closed wastewater treatment device from the upper part thereof, a catalyst is added into the wastewater, a gas containing ozone is continuously introduced into the wastewater from the lower part thereof for wastewater treatment, ozone tail gas generated during the wastewater treatment process is collected at the top of the closed wastewater treatment device and discharged after being rendered harmless, and the treated wastewater is continuously or batch-discharged; during the wastewater treatment process, the catalyst catalyzes ozone to generate surface hydroxyl radicals and surface atomic oxygen adsorbed on the surface of the catalyst to degrade organic pollutants in the wastewater; the catalyst is a nano-scale copper-cobalt bimetallic catalyst, which is composed of CuO and Co3O4, and CuO and Co3O4 form a heterogeneous structure.

2. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to claim 1, characterized in that: The preparation method of the catalyst is as follows: adding a copper source and ZIF-67 to a solvent in a mass percentage of (40% to 60%): (40% to 60%), fully reacting at 120 to 240° C., separating the solid and the liquid, washing the obtained solid phase with a solvent, and then crushing to obtain a reaction precursor, calcining the reaction precursor at 350 to 550° C. for 1 to 5 hours, washing to remove unreacted substances in the calcined product, drying, and crushing to obtain the catalyst.

3. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to claim 2 is characterized in that: When preparing the catalyst, the reaction time of the copper source and ZIF-67 at 120-240° C. is controlled to be 4-12 hours.

4. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to claim 2, characterized in that: The preparation method of ZIF-67 is as follows: a cobalt source and dimethylimidazole are fully mixed in a solvent according to a mass percentage of (37% to 47%): (53% to 63%), reacted at 20 to 50° C. for 0.5 to 4 hours, and then allowed to stand and precipitate at room temperature for 24 to 48 hours to obtain the ZIF-67.

5. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to claim 2, characterized in that: When preparing the catalyst, the reaction precursor is calcined in an atmosphere of air, oxygen or a mixed gas of air and oxygen.

6. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to any one of claims 1 to 5, characterized in that: The dosage of catalyst in wastewater is controlled to be 0.2-10 g / L.

7. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to any one of claims 1 to 5, characterized in that: Ozone-containing gas is introduced into the wastewater at a rate of 0.4 to 5 mmol of ozone per liter of wastewater per minute.

8. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to any one of claims 1 to 5, characterized in that: The ozone-containing gas is air containing ozone or oxygen containing ozone.

9. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to any one of claims 1 to 5, characterized in that: Control the pH value of wastewater to 3-11.

10. The method for advanced wastewater treatment based on surface catalytic ozone oxidation according to any one of claims 1 to 5, characterized in that: When the treatment method of continuously introducing wastewater and continuously discharging treated wastewater is adopted, the hydraulic retention time of the wastewater in the closed wastewater treatment system is controlled to be 30 to 120 minutes; when the treatment method of batch introducing wastewater and batch discharging treated wastewater is adopted, the wastewater treatment time is controlled to be 20 to 180 minutes.

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