A method for improving the efficiency of activating persulfate by a catalyst

Abstract

The present invention provides a method for improving the efficiency of a catalyst in activating persulfate, comprising the following steps: (1) taking an organic pollutant-contaminated environmental medium containing or not containing fluoride ions as a treatment object, adjusting the fluoride ion content of the treatment object to obtain a medium to be treated; (2) adding a catalyst for activating persulfate to generate advanced oxidation active species to the medium to be treated, so that the catalyst fully interacts with the fluoride ions in the medium to be treated; after the catalyst interacts with the fluoride ions in the medium to be treated, the efficiency of the catalyst in activating persulfate to generate advanced oxidation active species can be improved; (3) adding persulfate to the medium to be treated, and using the catalyst after interacting with the fluoride ions to activate persulfate to generate advanced oxidation species to degrade the organic matter in the medium to be treated. The method of the present invention can effectively improve the activation ability of the catalyst for persulfate and improve the degradation effect on organic pollutants.

Description

Technical Field

[0001] The invention belongs to the field of advanced oxidation for solid and liquid treatment, and relates to a method for improving the efficiency of catalyst activation persulfate. Background Art

[0002] Organic pollutants pose a serious threat to human health and the ecological environment. The environmental pollution caused by organic pollutants has become one of the focal issues of social and public concern. Advanced oxidation technology is a technology that uses hydrogen peroxide, oxygen, ozone, persulfate, peracetic acid, etc. as oxidants, and transition metals such as iron, cobalt, nickel, and copper as catalysts to catalyze the oxidants to produce free radicals and other highly oxidizing active species to oxidize and degrade pollutants. This technology can effectively remove organic pollutants in different media, has the advantages of high treatment efficiency and wide application range, and has been widely used in media such as water, soil, and mud. Among many oxidants, persulfates, such as monopersulfate and dipersulfate, have the advantages of low cost, high oxidation activity, and easy activation, and have received widespread attention.

[0003] The technology of activating persulfate is divided into homogeneous activation and heterogeneous activation. Homogeneous activation is to activate persulfate to produce advanced oxidation active species by using dissolved metal ions, and heterogeneous activation is to activate persulfate to produce advanced oxidation active species by using non-dissolved solid phase as catalyst. Both methods have their own advantages and disadvantages. Heterogeneous activation has the characteristics of catalyst recovery, small secondary pollution and wide pH application range, but its disadvantages are high catalyst preparation cost, complicated recovery process and low utilization rate of metal active sites. Therefore, for heterogeneous activation of persulfate, if the efficiency of catalyst activation of persulfate to produce advanced oxidation active species can be further improved, it will be very beneficial to reduce the treatment cost of organic pollutants. The utilization rate of metal atoms in homogeneous activation is high. Under the condition of the same catalyst addition amount, homogeneous activation usually has better effect than heterogeneous activation. However, the biggest problem of homogeneous activation of persulfate is that the catalyst is difficult to recover. On the one hand, the dissolved catalyst will cause secondary pollution. On the other hand, alkali needs to be added to form metal mud during the catalyst recovery process. These metal muds usually need to be treated as hazardous waste because they contain organic pollutants, which greatly increases the treatment cost of organic pollutants. Therefore, how to improve the efficiency of heterogeneous catalyst activation of persulfate so as to reduce the amount of homogeneous catalyst while maintaining a good treatment effect, thereby reducing the amount of metal sludge generated, is one of the key issues to be urgently addressed in the field of homogeneous activation of persulfate.

[0004] Currently, there have been reports on adding small - molecule acids such as ethylenediaminetetraacetic acid, citric acid, picolinic acid or their salts to complex with metals, changing the redox potential of metals to promote valence cycling and improve the catalytic effect. However, there are still some problems with the above - mentioned methods. For example, these small - molecule acids are usually not contained in wastewater and need to be added in relatively large amounts, which will cause a further increase in the organic matter concentration of the system, increase the treatment pressure of the system, and easily interfere with the efficient degradation of organic pollutants in the system; these small - molecule acids will be degraded by the advanced oxidation system, resulting in a decrease in the concentration of these small - molecule acids in the middle and late stages of treatment, leading to a weakening of the promotion effect brought by the small - molecule acids; these small - molecule acids are difficult to effectively strengthen the activation ability of heterogeneous catalysts. Therefore, there is still an urgent need to develop a catalytic promotion method that can further improve the efficiency of activating persulfate to generate advanced oxidation species. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide a method for improving the efficiency of a catalyst in activating persulfate, so as to further improve the activation ability and efficiency of a catalyst containing Co(II) or / and Co(III), and containing Cu(I) or / and Cu(II) for persulfate, and improve the degradation effect of organic pollutants.

[0006] The main technical concept of the present invention is to utilize the interaction between fluoride ions (F⁻) and a catalyst containing Co(II) or / and Co(III), or a catalyst containing Cu(I) or / and Cu(II) to form Co(F) n m - or Cu(F) n m- , change the redox potential of the catalyst, and then improve the ability and efficiency of the catalyst to activate persulfate to generate advanced oxidation active species.

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

[0008] A method for improving the efficiency of a catalyst in activating persulfate, comprising the following steps:

[0009] (1) Using an organic - matter - contaminated environmental medium containing or not containing fluoride ions as the treatment object, adjusting the fluoride ion content of the treatment object to obtain a medium to be treated; the fluoride ion content in the medium to be treated is 3 - 50 mmol / L;

[0010] (2) Add a catalyst for activating persulfate to generate advanced oxidation active species to the to-be-treated medium obtained in step (1) so that the catalyst fully interacts with fluoride ions in the to-be-treated medium; the catalyst is a catalyst containing Co(II) or / and Co(III), or a catalyst containing Cu(I) or / and Cu(II); after the catalyst interacts with fluoride ions in the to-be-treated medium, the efficiency of the catalyst for activating persulfate to generate advanced oxidation active species can be improved;

[0011] (3) Add persulfate to the to-be-treated medium treated in step (2), and use the catalyst after interacting with fluoride ions to activate persulfate to generate advanced oxidation species to degrade the organic matter in the to-be-treated medium.

[0012] In the above technical solution, the catalyst containing Co(II) or / and Co(III) is a homogeneous Co(II) or / and Co(III) catalyst, or a heterogeneous catalyst containing Co(II) or / and Co(III). The heterogeneous catalyst containing Co(II) or / and Co(III) includes at least one of cobalt oxides, cobalt metalates, cobalt nitride compounds, cobalt oxides supported on a carrier, cobalt metalates supported on a carrier, and cobalt nitride compounds supported on a carrier. Further, the cobalt oxides include cobalt oxide, cobalt tetroxide, etc., the cobalt metalates include cobalt ferrite, etc., and the cobalt nitride compounds include compounds containing cobalt-nitrogen bonds, such as cobalt nitride, or other materials containing cobalt-nitrogen bonds. The homogeneous Co(II) or / and Co(III) catalyst is a water-soluble divalent or trivalent cobalt salt.

[0013] In the above technical solution, the catalyst containing Cu(I) or / and Cu(II) is a homogeneous Cu(I) or / and Cu(II) catalyst, or a heterogeneous catalyst containing Cu(I) or / and Cu(II). The heterogeneous catalyst containing Cu(I) or / and Cu(II) includes at least one of copper oxides, copper metalates, copper nitride compounds, copper oxides supported on a carrier, copper metalates supported on a carrier, and copper nitride compounds supported on a carrier. Further, the copper oxides include copper oxide, cuprous oxide, etc., the copper metalates include copper ferrite, etc., and the copper nitride compounds include compounds containing copper-nitrogen bonds, such as copper nitride, or other materials containing copper-nitrogen bonds. The homogeneous Cu(I) or / and Cu(II) catalyst is a water-soluble monovalent or divalent copper salt.

[0014] In the above technical solution, the addition amounts of the catalyst and the persulfate can be determined comprehensively according to factors such as the types and contents of organic pollutants in the environmental medium, and the state of the environmental medium, for example, whether the environmental medium is wastewater, sediment or soil, etc. Generally, the addition amount of the catalyst in step (2) is 0.1 - 3000 μmol added per liter of the medium to be treated, and the addition amount of the persulfate in step (3) is 0.01 - 100 mmol added per liter of the medium to be treated.

[0015] In step (3) of the above technical solution, the organic matter in the medium to be treated can be degraded under the conditions of stirring or shaking, or in a fluidized bed or a fixed bed.

[0016] In the above technical solution, the time for degrading the organic matter in step (3) is determined according to actual application requirements. For example, the degradation can be stopped when the removal rate of the organic matter reaches the expected target, or the degradation can also be stopped when the removal rate of the organic matter basically reaches the equilibrium state. Depending on the type of the environmental medium and the types and concentrations of the organic matter, the degradation time of step (3) will be different. Generally speaking, the degradation time of step (3) does not exceed 1200 min.

[0017] In step (2) of the above technical solution, the interaction time between the catalyst and the fluoride ions in the medium to be treated is at least 5 min. Preferably, the interaction time between the catalyst and the fluoride ions in the medium to be treated is controlled to be 5 - 60 min. Similarly, in step (2), the catalyst and the fluoride ions in the medium to be treated can also be made to interact fully under the conditions of stirring or shaking, or in a fluidized bed or a fixed bed.

[0018] In the above technical solution, the treatment object in step (1) includes any one of natural water bodies, municipal sewage, industrial wastewater, agricultural non-point source polluted water, river and reservoir sediment, activated sludge, and polluted soil.

[0019] In step (1) of the above technical solution, according to the different states of the treatment object, the state of the treatment object can be adjusted to a level suitable for organic matter degradation and the fluoride ion content of the treatment object can be adjusted by at least one of the methods of adding water, pressure filtration to remove water, adjusting the pH value, heating, and rinsing to obtain the medium to be treated.

[0020] In step (1) of the above technical solution, adjusting the fluoride ion content of the treatment object means adjusting the fluoride ion content in the object to be treated to the desired level. For example, the fluoride ion content in the medium to be treated can be controlled to be 3 - 50 mmol / L. When it is necessary to add fluoride ions to the treatment object to adjust the fluoride ion content of the treatment object, usually a fluoride ion-containing salt can be added, such as sodium fluoride, potassium fluoride, etc.

[0021] In the above technical solution, the persulfate is at least one of monopersulfate and dipersulfate.

[0022] In order to avoid secondary pollution caused by fluoride ions, in the above technical solution, after the treatment in step (3), it is preferably further included to remove fluoride ions in step (4). The operation of removing fluoride ions can be carried out with reference to the prior art. For example, the fluoride ions in the medium treated in step (3) can be removed by coagulation method, adsorption method, etc.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0024] 1. The present invention provides a method for improving the efficiency of activating persulfate by a catalyst, mainly by using the interaction between fluoride ions (F-) and a catalyst containing Co(II) or / and Co(III), and containing Cu(I) or / and Cu(II) to form Co(F) n m- or Cu(F) n m- , change the redox potential of the catalyst, improve the ability and efficiency of the catalyst to activate persulfate to generate advanced oxidation active species, and then improve the ability and efficiency of the persulfate advanced oxidation system to remove organic substances in the environmental medium. On the one hand, fluoride ions are widely present in the wastewater of photovoltaic, electrolytic aluminum, glass factories, pesticide production, etc., as well as in the silt of rivers and reservoirs. When degrading organic substances in these environmental media, no additional fluoride ions or only a small amount of additional fluoride ions are required. Thus, the problem that the concentration of organic substances in the system increases due to the large amount of additional organic small molecule acids in the prior art, increasing the treatment pressure of the system and interfering with the normal advanced oxidation reaction can be solved; on the other hand, fluoride ions basically do not react with the advanced oxidation active species generated in the system, so fluoride ions basically do not lose during the process of degrading pollutants, do not interfere with the degradation of organic substances, and do not cause the reduction of the strengthening effect in the later stage of degradation; on the third hand, this method is applicable to improving the ability of both homogeneous and heterogeneous catalysts to activate persulfate, and has the advantage of a wide application range. Compared with the prior art method of promoting the ability of a catalyst to activate persulfate by adding organic small molecule acids, the method provided by the present invention can more efficiently and greenly achieve the removal of organic pollutants.

[0025] 2. The present invention has been verified through experiments that the method of the present invention can effectively improve the ability of the catalyst to activate persulfate to generate advanced oxidation active species. Compared with the situation where there is no fluoride ion in the environmental medium and no additional fluoride ion is added, the method of the present invention has a significantly higher removal rate of organic pollutants under the same catalyst dosage and degradation time, effectively improving the degradation efficiency of organic pollutants. At the same time, since the method of the present invention improves the ability of the catalyst to activate persulfate, the method of the present invention can achieve a higher removal rate of organic pollutants with a smaller catalyst dosage compared with the situation where there is no fluoride and no additional fluoride ion in the environmental medium. For homogeneous catalysis, the above characteristics are beneficial to reducing the dosage of homogeneous catalyst and the generation amount of metal sludge, which is very beneficial for reducing the treatment cost of metal sludge and avoiding the pollution caused by metal sludge. For heterogeneous catalysis, the above characteristics are beneficial to reducing the dosage of heterogeneous catalyst, which is also very beneficial for reducing the cost of heterogeneous catalyst.

[0026] 3. The method of the present invention is simple to operate and has a good promoting effect on the ability and efficiency of the catalyst to activate persulfate, which is worthy of and beneficial to be popularized and applied in actual scenarios. Detailed implementation manners

[0027] The method for improving the efficiency of the catalyst to activate persulfate according to the present invention will be further described below 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 based on the above-mentioned invention content and conduct specific implementations, which still fall within the protection scope of the invention.

[0028] Example 1

[0029] In this example, a method for improving the efficiency of the catalyst to activate persulfate according to the present invention is provided, and the steps are as follows:

[0030] (1) Using a 10 μmol / L aqueous solution of carbamazepine as the treatment object, add NaF to the aqueous solution of carbamazepine until the fluoride ion concentration is 5 mmol / L. At this time, the pH value of the solution is about 6.8, which is denoted as the wastewater to be treated.

[0031] (2) Add Co(NO3)2·6H2O to the wastewater to be treated obtained in step (1). The addition amount of Co(NO3)2·6H2O is 0.17 μmol per liter of wastewater, and then mechanically stir for 5 min to make Co 2+ interact fully with F -

[0032] ​(3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 200 μmol per liter of wastewater. Under mechanical stirring conditions, use Co after interacting with fluoride ions 2+ to activate persulfate to generate sulfate radicals for the degradation of carbamazepine. At 40 min after adding persulfate, take a sample to measure the carbamazepine concentration and calculate the removal rate of carbamazepine. The results show that the removal rate of carbamazepine is 93% at 40 min after adding persulfate.

[0033] (4) Add the coagulant aluminum chloride to the wastewater treated in step (3). The addition amount of aluminum chloride is 1000 mg per liter of wastewater. After 60 min of flocculation treatment, 93% of the fluoride ions in the wastewater can be removed.

[0034] Comparative Example 1

[0035] In this comparative example, NaF is not added for comparison with Example 1. The steps are as follows:

[0036] (1) Use an aqueous solution of carbamazepine at 10 μmol / L as the treatment object. The pH value of this solution is about 6.8, denoted as the wastewater to be treated.

[0037] (2) Add Co(NO3)2·6H2O to the wastewater to be treated obtained in step (1). The addition amount of Co(NO3)2·6H2O is 0.17 μmol per liter of wastewater, and then stir mechanically for 5 min to make Co 2+ interact fully with fluoride ions.

[0038] (3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 200 μmol per liter of wastewater. Under mechanical stirring conditions, activate persulfate to generate sulfate radicals for the degradation of carbamazepine through Co 2+ At 40 min and 180 min after adding persulfate, take samples to measure the carbamazepine concentration and calculate the removal rate of carbamazepine. The results show that the removal rate of carbamazepine is 38% at 40 min after adding persulfate and 48% at 180 min after adding persulfate.

[0039] Combining Example 1 and Comparative Example 1, it can be seen that under the condition of the same addition amount of the homogeneous catalyst Co 2+ In the presence of fluoride ions in Example 1, the removal rate of carbamazepine is as high as 93% at 40 min after adding persulfate, while in Comparative Example 1 without the presence of fluoride ions, the removal rates of carbamazepine are only 38% and 48% respectively at 40 min and 180 min after adding persulfate. This shows that the presence of fluoride ions in the wastewater can effectively improve the homogeneous catalyst Co 2+The ability of activated persulfate to generate sulfate radicals.

[0040] Comparative Example 2

[0041] In this comparative example, NaF was not added for comparison with Example 1. The steps are as follows:

[0042] (1) An aqueous solution of carbamazepine at 10 μmol / L was used as the treatment object. The pH value of this solution was about 6.8 and was denoted as the wastewater to be treated.

[0043] (2) Co(NO3)2·6H2O was added to the wastewater to be treated obtained in step (1). The addition amount of Co(NO3)2·6H2O was 0.5 μmol per liter of wastewater, and then mechanical stirring was carried out for 5 min.

[0044] (3) Persulfate was added to the wastewater obtained in step (2). The addition amount of persulfate was 200 μmol per liter of wastewater. Under the condition of mechanical stirring, Co 2+ activated persulfate to generate sulfate radicals for the degradation of carbamazepine. At 40 min after adding persulfate, a sample was taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine. The results showed that the removal rate of carbamazepine was 57% at 40 min after adding persulfate.

[0045] Combined with Example 1 and Comparative Example 3, it can be seen that in the case of not adding fluoride ions, Comparative Example 2 added 3 times the heterogeneous catalyst Co 2+ as that in Example 1. At 40 min after adding persulfate, the removal rate of carbamazepine was only 57%, which was much lower than 93% in Example 1. It shows that the presence of fluoride ions in the wastewater can effectively improve the ability of heterogeneous Co 2+ to activate persulfate to generate sulfate radicals and can significantly reduce the dosage of the heterogeneous catalyst.

[0046] Comparative Example 3

[0047] In this comparative example, Al(NO3)3·9H2O was used to replace Co(NO3)2·6H2O in Example 1 for comparison with Example 1. The steps are as follows:

[0048] (1) The operation was the same as that in Example 1.

[0049] (2) Al(NO3)3·9H2O was added to the wastewater to be treated obtained in step (1). The addition amount of Al(NO3)3·9H2O was 10 mmol per liter of wastewater, and then mechanical stirring was carried out for 5 min.

[0050] (3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 200 μmol per liter of wastewater, and carbamazepine is degraded under mechanical stirring conditions. At 40 min after adding persulfate, a sample is taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine. The results show that the removal rate of carbamazepine is 23% at 40 min after adding persulfate.

[0051] Comparative Example 4

[0052] In this comparative example, Al(NO3)3·9H2O and Co(NO3)2·6H2O are added simultaneously for comparison with Example 1. The steps are as follows:

[0053] (1) The operation is the same as that in Example 1.

[0054] (2) Add Al(NO3)2·9H2O and Co(NO3)2·6H2O to the wastewater to be treated obtained in step (1). The addition amounts of Al(NO3)2·9H2O and Co(NO3)2·6H2O are 10 mmol and 0.17 μmol per liter of wastewater respectively, and then stir mechanically for 5 min.

[0055] (3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 200 μmol per liter of wastewater, and carbamazepine is degraded under mechanical stirring conditions. At 40 min after adding persulfate, a sample is taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine. The results show that the removal rate of carbamazepine is 24% at 40 min after adding persulfate.

[0056] It is known that Al 3+ is a strong complexing agent for F - Combined with Example 1 and Comparative Examples 3 - 4, it can be seen that the addition of Al 3+ almost completely inhibits the strengthening effect of F - on the activation of persulfate by Co 2+ This is because Al 3+ undergoes a complexation reaction with F−, and F− can no longer interact with Co 2+ to form Co(F) n m- . This experimental result also shows that in the present invention, the strengthening effect of F− on the activation of persulfate by Co 2+ is achieved by the reaction of Co 2+ with F− to generate Co(F) n m- .

[0057] Example 2

[0058] In this example, the effect of the addition amount of F− on the activation of Co 2+The influence of activated persulfate is as follows:

[0059] (1) Using a 10 μmol / L aqueous solution of carbamazepine as the treatment object, different amounts of NaF were added to the aqueous solution of carbamazepine to obtain 5 groups of wastewater. The pH value of each group of wastewater was approximately 6.8. In each group of wastewater, the concentration of carbamazepine was 10 μmol / L, and the concentrations of fluoride ions were 0, 1, 3, 5, and 7 mmol / L, respectively.

[0060] (2) Co(NO3)2·6H2O was added to each group of wastewater obtained in step (1). The addition amount of Co(NO3)2·6H2O was 0.17 μmol per liter of wastewater, and then mechanical stirring was carried out for 5 min.

[0061] (3) Persulfate was added to each group of wastewater obtained in step (2). The addition amount of persulfate in each group of wastewater was 200 μmol per liter of wastewater, and carbamazepine was degraded under mechanical stirring conditions. At 40 min after adding persulfate, samples were taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine. The results showed that at 40 min after adding persulfate, when the concentrations of fluoride ions in the wastewater were 0, 1, 3, 5, and 7 mmol / L, the removal rates of carbamazepine were 38%, 56%, 88%, 93%, and 97%, respectively.

[0062] It can be seen from this example that compared with the situation where there is no fluoride ion in the wastewater, after adding fluoride ions, the removal efficiency of carbamazepine has been improved to varying degrees. Especially when the content of fluoride ions in the wastewater reaches 3 mmol / L or more, the removal rate of carbamazepine reaches a level close to or above 90%. This is mainly because fluoride ions improve the catalyst Co 2+ The result of the efficiency of generating free radicals by activating persulfate.

[0063] Example 3

[0064] The operation of this example is basically the same as that of Example 1, except that in step (2), the heterogeneous catalyst CoFe2O4 is used to replace the homogeneous catalyst Co(NO3)2·6H2O in Example 1. The addition amount of the heterogeneous catalyst CoFe2O4 is 855 μmol / L per liter of wastewater; in step (3), at 20 min after adding persulfate, samples were taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine.

[0065] The results showed that the removal rate of carbamazepine reached 99% at 20 min after adding persulfate in this example.

[0066] Comparative Example 5

[0067] This comparative example is used for comparison with Example 3. The operation of this comparative example is basically the same as that of Comparative Example 1, except that in step (2), the heterogeneous catalyst CoFe2O4 is used to replace the homogeneous catalyst Co(NO3)2·6H2O in Comparative Example 1, and the addition amount of CoFe2O4 is 855 μmol / L per liter of wastewater; in step (3), when persulfate is added for 20 min and 40 min, samples are taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine.

[0068] The results show that the removal rate of carbamazepine in this comparative example is 57% when persulfate is added for 20 min, and the removal rate of carbamazepine is 91% when persulfate is added for 40 min.

[0069] Combined with Example 3 and Comparative Example 5, it can be seen that under the condition of the same addition amount of the heterogeneous catalyst, in the presence of fluoride ions in Example 3, the removal efficiency of carbamazepine is significantly higher than the removal rate of carbamazepine without fluoride ions in Comparative Example 5. It shows that the presence of fluoride ions in the wastewater can effectively improve the ability of the heterogeneous catalyst to activate persulfate to generate sulfate radicals.

[0070] Example 4

[0071] The operation of this example is basically the same as that of Example 1, except that in step (2), the heterogeneous catalyst Co3O4 is used to replace the homogeneous catalyst Co(NO3)2·6H2O in Example 1, and the addition amount of Co3O4 is 831 μmol / L per liter of wastewater; in step (3), when persulfate is added for 30 min, a sample is taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine.

[0072] The results show that the removal rate of carbamazepine in this example reaches 99% when persulfate is added for 30 min.

[0073] Comparative Example 6

[0074] This comparative example is used for comparison with Example 4. The operation of this comparative example is basically the same as that of Comparative Example 1, except that in step (2), the heterogeneous catalyst Co3O4 is used to replace the homogeneous catalyst Co(NO3)2·6H2O in Comparative Example 1, and the addition amount of Co3O4 is 831 μmol / L per liter of wastewater; in step (3), when persulfate is added for 30 min, a sample is taken to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine.

[0075] The results show that the removal rate of carbamazepine in this comparative example is 60% when persulfate is added for 30 min.

[0076] Combined with Example 4 and Comparative Example 6, it can be seen that under the condition of the same addition amount of heterogeneous catalyst, in the presence of fluoride ions in Example 4, the removal efficiency of carbamazepine is significantly higher than that of Comparative Example 6 without the addition of fluoride ions. This shows that the presence of fluoride ions in the wastewater can effectively improve the ability of the heterogeneous catalyst to activate peroxymonosulfate to generate sulfate radicals.

[0077] Example 5

[0078] In this example, a method for improving the efficiency of catalyst activation of persulfate of the present invention is provided, and the steps are as follows:

[0079] (1) Taking reservoir sediment containing 11 mmol / L fluoride ions and 53 μmol / L sulfamethoxazole as the treatment object, adding water to the reservoir sediment according to the volume ratio of reservoir sediment to water of 2:3, mixing well, and then adjusting the pH value to 5. The resulting product is denoted as the sediment to be treated. In this sediment to be treated, the concentration of fluoride ions is 4.4 mmol / L.

[0080] (2) Adding Co(NO3)2·6H2O to the sediment to be treated obtained in step (1). The addition amount of Co(NO3)2·6H2O is 0.17 μmol per liter of the sediment to be treated. Then, mix well by shaking on a shaker for 20 min to make Co 2+ interact fully with fluoride ions.

[0081] (3) Adding persulfate to the sediment treated in step (2). The addition amount of persulfate is 2000 μmol per liter of the sediment to be treated. Under the condition of mechanical stirring, use Co after interacting with fluoride ions 2+ to activate persulfate to generate sulfate radicals for degrading sulfamethoxazole. At 180 min after adding persulfate, take a sample to measure the concentration of sulfamethoxazole and calculate the removal rate of sulfamethoxazole. The results show that at 180 min after adding persulfate, the removal rate of sulfamethoxazole in the reservoir sediment containing 11 mmol / L F- and 53 μmol / L sulfamethoxazole is 73%.

[0082] Example 6

[0083] In this example, a method for improving the efficiency of catalyst activation of persulfate of the present invention is provided, and the steps are as follows:

[0084] (1) Taking an aqueous solution of methylene blue at 5 μmol / L as the treatment object, adding NaF to the aqueous solution of methylene blue until the fluoride ion concentration is 20 mmol / L. At this time, the pH value of the solution is about 7, which is denoted as the wastewater to be treated.

[0085] (2) Add Co(NO3)2·6H2O to the wastewater to be treated obtained in step (1). The addition amount of Co(NO3)2·6H2O is 0.17 μmol per liter of wastewater, and then stir mechanically for 10 min to allow Co 2+ to interact fully with fluoride ions.

[0086] (3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 1000 μmol per liter of wastewater. Under the condition of mechanical stirring, use Co 2+ after its interaction with fluoride ions to activate persulfate to generate sulfate radicals for degrading methylene blue. At 200 min after adding persulfate, take a sample to measure methylene blue and calculate the removal rate of methylene blue. The results show that the removal rate of methylene blue exceeds 99% at 200 min after adding persulfate.

[0087] Example 7

[0088] In this example, a method for improving the efficiency of catalyst-activated persulfate of the present invention is provided, and the steps are as follows:

[0089] (1) Take actual electroplating wastewater as the treatment object. After measurement, the concentration of fluoride ions in the electroplating wastewater is 25 mg / L and the TOC concentration is 18 mg / L.

[0090] (2) Add Co(NO3)2·6H2O to the electroplating wastewater. The addition amount of Co(NO3)2·6H2O is 10 μmol per liter of electroplating wastewater, and then stir mechanically for 10 min to allow Co 2+ to interact fully with fluoride ions.

[0091] (3) Add persulfate to the wastewater treated in step (2). The addition amount of persulfate is 3000 μmol per liter of wastewater. Under the condition of mechanical stirring, use Co 2+ after its interaction with fluoride ions to activate persulfate to generate sulfate radicals for degrading methylene blue. At 1200 min after adding persulfate, take a sample to measure the TOC concentration and calculate the removal rate of TOC. The results show that the removal rate of TOC in the electroplating wastewater is 73% at 1200 min after adding persulfate.

[0092] Example 8

[0093] In this example, a method for improving the efficiency of catalyst-activated persulfate of the present invention is provided, and the steps are as follows:

[0094] (1) Take a 10 μmol / L aqueous solution of carbamazepine as the treatment object, add NaF to the aqueous solution of carbamazepine until the fluoride ion concentration is 5 mmol / L. At this time, the pH value of the solution is about 6.8, which is recorded as the wastewater to be treated.

[0095] (2) Add copper nitrate to the wastewater to be treated obtained in step (1). The addition amount of copper nitrate is 3 mmol per liter of wastewater, and then mechanically stir for 5 min to allow Cu 2+ to interact fully with F - .

[0096] (3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 200 μmol per liter of wastewater. Under the condition of mechanical stirring, use Cu 2+ after interacting with fluoride ions to activate persulfate to generate sulfate radicals for degrading carbamazepine. At 40 min after adding persulfate, take a sample to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine. The results show that the removal rate of carbamazepine is 86% at 40 min after adding persulfate.

[0097] Comparative Example 7

[0098] In this comparative example, NaF is not added for comparison with Example 8. The steps are as follows:

[0099] (1) Use an aqueous solution of carbamazepine at 10 μmol / L as the treatment object. The pH value of this solution is about 6.8, denoted as the wastewater to be treated.

[0100] (2) Add copper nitrate to the wastewater to be treated obtained in step (1). The addition amount of copper nitrate is 3 mmol per liter of wastewater, and then mechanically stir for 5 min.

[0101] (3) Add persulfate to the wastewater obtained in step (2). The addition amount of persulfate is 200 μmol per liter of wastewater. Under the condition of mechanical stirring, use Cu 2+ to activate persulfate to generate sulfate radicals for degrading carbamazepine. At 40 min after adding persulfate, take a sample to measure the concentration of carbamazepine and calculate the removal rate of carbamazepine. The results show that the removal rate of carbamazepine is 53% at 40 min after adding persulfate.

[0102] Combined with Example 8 and Comparative Example 7, it can be seen that under the condition of the same addition amount of the homogeneous catalyst Cu 2+ , in Example 8, in the presence of fluoride ions, the removal rate of carbamazepine is as high as 86% at 40 min after adding persulfate, while in Comparative Example 7, in the absence of fluoride ions, the removal rate of carbamazepine is only 53% at 40 min after adding persulfate. This shows that the presence of fluoride ions in the wastewater can effectively improve the ability of the homogeneous catalyst Cu 2+ to activate persulfate to generate sulfate radicals.

Claims

1. A method for improving the efficiency of a catalyst in activating persulfate, characterized in that, It includes the following steps: (1) Using an environmental medium contaminated by organic matter with or without fluoride ions as the treatment object, adjusting the fluoride ion content of the treatment object to obtain a medium to be treated; the fluoride ion content in the medium to be treated is 3-50 mmol / L; (2) Adding a catalyst for activating persulfate to generate advanced oxidation active species to the medium to be treated obtained in step (1), so that the catalyst fully interacts with the fluoride ions in the medium to be treated; the catalyst is a catalyst containing Co(II) or / and Co(III), or a catalyst containing Cu(I) or / and Cu(II); after the catalyst interacts with the fluoride ions in the medium to be treated, it can improve the efficiency of the catalyst to activate persulfate to generate advanced oxidation active species; (3) Adding persulfate to the medium to be treated after being treated in step (2), and using the catalyst after interacting with fluoride ions to activate persulfate to generate advanced oxidation species to degrade the organic matter in the medium to be treated.

2. The method for improving the efficiency of a catalyst in activating persulfate according to claim 1, characterized in that, The catalyst containing Co(II) or / and Co(III) is a homogeneous Co(II) or / and Co(III) catalyst, or a heterogeneous catalyst containing Co(II) or / and Co(III). The heterogeneous catalyst containing Co(II) or / and Co(III) includes at least one of cobalt oxide, cobalt metalate, cobalt nitride compound, cobalt oxide supported on a carrier, cobalt metalate supported on a carrier, and cobalt nitride compound supported on a carrier.

3. The method for improving the efficiency of a catalyst in activating persulfate according to claim 1, characterized in that, The catalyst containing Cu(I) or / and Cu(II) is a homogeneous Cu(I) or / and Cu(II) catalyst, or a heterogeneous catalyst containing Cu(I) or / and Cu(II). The heterogeneous catalyst containing Cu(I) or / and Cu(II) includes at least one of copper oxide, copper metalate, copper nitride compound, copper oxide supported on a carrier, copper metalate supported on a carrier, and copper nitride compound supported on a carrier.

4. The method for improving the efficiency of a catalyst in activating persulfate according to claim 1, characterized in that, In step (2), the addition amount of the catalyst is 0.1-3000 μmol of catalyst per liter of the medium to be treated.

5. The method for improving the efficiency of a catalyst in activating persulfate according to claim 1, characterized in that, In step (3), the addition amount of persulfate is 0.01-100 mmol of persulfate per liter of the medium to be treated.

6. The method for improving the efficiency of a catalyst in activating persulfate according to any one of claims 1 to 5, characterized in that, In step (2), the interaction time between the catalyst and the fluoride ions in the medium to be treated is controlled to be 5-60 min.

7. The method for improving the efficiency of a catalyst in activating persulfate according to any one of claims 1 to 5, characterized in that, The treatment object in step (1) includes any one of natural water bodies, municipal sewage, industrial wastewater, agricultural non-point source polluted water, river and reservoir siltation, activated sludge, and polluted soil.

8. The method for improving the efficiency of a catalyst in activating persulfate according to any one of claims 1 to 5, characterized in that, In step (1), the state of the treatment object is adjusted to a level suitable for organic matter degradation and the fluoride ion content of the treatment object is adjusted by at least one of adding water, pressure filtration to remove water, adjusting the pH value, heating, and leaching to obtain a medium to be treated.

9. The method for improving the efficiency of a catalyst in activating persulfate according to any one of claims 1 to 5, characterized in that, The persulfate is at least one of peroxymonosulfate and peroxydisulfate.

10. The method for improving the efficiency of a catalyst in activating persulfate according to any one of claims 1 to 5, characterized in that, After being treated in step (3), it further includes step (4) of removing fluoride ions.