Method for degrading organic pollutants

Abstract

The invention discloses a method for degrading organic pollutants, and relates to the technical field of water pollution control engineering. The preparation method comprises the following steps: mixing and grinding cobalt slag and red mud, and roasting to obtain a composite material with cobalt and iron as main active components; mixing the roasted material with persulfate to obtain a mixture; dispersing the mixture into a to-be-treated water body containing organic pollutants for degradation to obtain a degraded water body; the Co3O4-coated Fe2O3 with excellent catalytic performance is obtained by adopting a roasting method, and the Co3O4-coated Fe2O3 not only can adsorb organic pollutants, but also can activate persulfate to degrade the organic pollutants, so that deep catalytic oxidation of the pollutants is realized, and meanwhile, the leaching rate of metal ions is low; the Co3O4-coated Fe2O3 disclosed by the invention is widely applicable to various pollutants, has the characteristic that the Co3O4-coated Fe2O3 is slightly influenced by pH values and other common ions in water, and is applicable to water pollution treatment in various environments, and the reacted material can be repeatedly utilized after being roasted.

Description

Technical Field

[0001] The invention relates to the technical field of water pollution control engineering, in particular to a method for degrading organic pollutants. Background Art

[0002] With the population growth and the acceleration of industrialization, water pollution has become increasingly prominent. Among them, the deterioration of water environment caused by the large-scale discharge of dye-type pollutants, antibiotic pollutants and endocrine pollutants is particularly significant and has become one of the important problems of environmental pollution. The large-scale discharge of organic pollutants affects water quality, causing serious damage to the ecological environment of water bodies and threatening human health. In order to solve water problems such as water shortage, water environment pollution and degradation of water ecosystems, persulfate advanced oxidation is an economical, friendly and fast pollutant treatment technology with the advantages of high efficiency, environmental protection and strong oxidation ability. It can degrade pollutants into small molecular inorganic substances or CO in a short time. 2 and H 2 O. This technology has universal applicability and is widely used in the fields of industrial wastewater, drinking water and sewage treatment. It can effectively degrade most liquid organic pollutants while avoiding secondary pollution.

[0003] However, the adsorption and degradation efficiency of organic pollutants will be low, resulting in extended pollutant treatment time and affecting the water quality improvement effect. In addition, if the material has poor applicability to pH values ​​and coexisting ions, it will limit its application under different water quality conditions, resulting in unstable treatment effects. If the source of its preparation materials is not wide and the price is not competitive, or complex preparation conditions are required, it will increase the difficulty of large-scale production, thereby affecting the effective use of resources and sustainable development, and ultimately reducing its economic benefits and social value. In response to the above problems, the inventors propose a method for degrading organic pollutants to solve the above problems. Summary of the invention

[0004] To solve the problem of Co 3 O 4 @Fe 2 O 3 Lack of excellent catalytic performance, poor applicability or high preparation cost may lead to low efficiency in water pollution control, affecting economic benefits and sustainable development issues; the purpose of the present invention is to provide a method for degrading organic pollutants.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for degrading organic pollutants, comprising the following steps:

[0006] S1, mixing and grinding cobalt slag and red mud, and then roasting to obtain a composite material with cobalt and iron as main active components (Co 3 O 4@Fe 2 O 3 );

[0007] S2, mixing the material obtained after roasting with persulfate to obtain a mixture;

[0008] S3. Dispersing the mixture into a water body containing organic pollutants to be treated for degradation to obtain degraded water.

[0009] Preferably, the composite material is Co 3 O 4 @Fe 2 O 3 The mass ratio of the cobalt slag to the red mud is 0.25-4; the mass ratio of the composite material to the persulfate is 0.3-2; and the dosage of the mixture is 0.01-0.8 g / L.

[0010] Preferably, the cobalt slag and red mud are roasted at a temperature of 300° C. to 800° C., the cobalt slag and red mud are roasted for a time of 2 h to 8 h, and the heating rate of the cobalt slag and red mud is roasted at a rate of 3 to 10° C. / min.

[0011] Preferably, the cobalt slag and red mud in the composite material are both common mineral wastes with wide sources, low prices, and are solid wastes.

[0012] Preferably, the composite material has a particle size of 10 to 200 meshes.

[0013] Preferably, the persulfate is any one of potassium persulfate, sodium persulfate and potassium hydrogen persulfate.

[0014] Preferably, the degradation temperature is 15-30° C.; the degradation time is 5-60 min.

[0015] Preferably, the organic pollutant is any one or more of acid fuchsin, Congo red, methyl orange, tetracycline, doxycycline, and dibutyl phthalate.

[0016] Preferably, the calcination atmosphere includes any one of air, carbon dioxide, nitrogen and ammonia.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention obtains Co with excellent catalytic performance by using a roasting method 3 O 4 @Fe 2 O 3 ,Co 3 O 4 @Fe 2 O 3It can not only adsorb organic pollutants, but also activate persulfate to degrade organic pollutants, achieving deep catalytic oxidation of pollutants while minimizing the leaching rate of metal ions.

[0019] 2. Co in the present invention 3 O 4 @Fe 2 O 3 It is widely applicable to a variety of pollutants, and is less affected by pH value and other common ions in water. It is suitable for water pollution control in various environments, and it still maintains a good pollutant degradation effect after recycling. The reacted material can be reused after roasting.

[0020] 3. The materials prepared by the present invention are widely available and inexpensive, which is conducive to large-scale production. Chemical reagents and complex preparation conditions are not required, and resource utilization of waste minerals can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 For the present invention Co 3 O 4 @Fe 2 O 3 Schematic diagram of the degradation results of tetracycline in water.

[0023] Figure 2 For the present invention Co 3 O 4 The effect of the quality of the reagents on the degradation of Congo red, tetracycline, doxycycline, methyl orange and acid fuchsin.

[0024] Figure 3 The present invention Co 3 O 4 @Fe 2 O 3 Schematic diagram comparing the degradation results of Congo red, tetracycline, doxycycline, methyl orange and acid fuchsin.

[0025] Figure 4 The present invention Co 3 O 4 @Fe 2 O 3 Schematic diagram of the results of tetracycline degradation at different pH values.

[0026] Figure 5The present invention Co 3 O 4 @Fe 2 O 3 Schematic diagram of the results of tetracycline degradation in actual water bodies.

[0027] Figure 6 The present invention Co 3 O 4 @Fe 2 O 3 Schematic representation of the results of tetracycline degradation in water containing a large number of different ions. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1: Figure 1-5 As shown, the present invention provides a method for degrading organic pollutants using a composite material of cobalt slag-red mud and persulfate, comprising the following steps:

[0030] S1. Grind the red mud and cobalt slag together and collect them for later use. Put the ground materials into a crucible, heat them to 500°C at a rate of 5°C / min in an air atmosphere in a muffle furnace, and calcine them for 8 hours to obtain Co 3 O 4 @Fe 2 O 3 Materials: Co 3 O 4 @Fe 2 O 3 The mesh number is 100 mesh;

[0031] S2, 100 mg of Co 3 O 4 @Fe 2 O 3 The mixture was mixed with 100 mg of potassium persulfate to obtain a mixture, and 40 mg of the mixture was added into 100 mL of deionized water containing 20 mg / L tetracycline to degrade tetracycline in situ; the tetracycline was degraded at 20° C. for 30 min to obtain deionized water in which the tetracycline was completely degraded; the removal rate was calculated to be 99.2%.

[0032] Example 2

[0033] S1. Grind the red mud and cobalt slag together and collect them for later use. Put the ground materials into a crucible, heat them to 500°C at a rate of 5°C / min in an air atmosphere in a muffle furnace, and calcine them for 8 hours to obtain Co 3 O 4 @Fe 2 O 3 Materials: Co 3 O 4 @Fe 2 O 3 The mesh number is 100 mesh;

[0034] S2, 50 mg of Co 3 O 4 @Fe 2 O 3 and 150 mg of potassium persulfate to obtain a mixture, 15 mg of the mixture was added to 100 mL of an aqueous solution of 20 mg / L tetracycline to degrade tetracycline in situ; the tetracycline was degraded at 20° C. for 30 min to obtain an aqueous solution in which tetracycline was completely degraded; the removal rate was calculated to be 98.9%.

[0035] The aqueous solution contains cations such as sodium ions or anions such as nitrates and sulfates.

[0036] Example 3

[0037] S1. Grind the red mud and cobalt slag together and collect them for later use. Put the ground materials into a crucible, heat them to 500°C at a rate of 5°C / min in an air atmosphere in a muffle furnace, and calcine them for 8 hours to obtain Co 3 O 4 @Fe 2 O 3 Materials: Co 3 O 4 @Fe 2 O 3 The mesh number is 100 mesh;

[0038] S2, 100 mg of Co 3 O 4 @Fe 2 O 3 The mixture was mixed with 50 mg of potassium persulfate to obtain a mixture, and 30 mg of the mixture was added into 100 mL of tap water with a tetracycline concentration of 20 mg / L to degrade tetracycline in situ; the tetracycline was degraded at 20°C for 30 minutes to obtain tap water with completely degraded tetracycline; the removal rate was calculated to be 87.2%.

[0039] Example 4

[0040] S1. Grind the red mud and cobalt slag together and collect them for later use. Put the ground materials into a crucible, heat them to 500°C at a rate of 5°C / min in an air atmosphere in a muffle furnace, and calcine them for 8 hours to obtain Co 3 O 4 @Fe 2 O 3 Materials: Co 3 O 4 @Fe 2 O 3 The mesh number is 100 mesh;

[0041] S2, 100 mg of Co 3 O 4 @Fe 2 O 3 and 200 mg of potassium persulfate to obtain a mixture, 60 mg of the mixture was added into 100 mL of an aqueous solution with a Congo red concentration of 20 mg / L to degrade tetracycline in situ; the tetracycline was degraded at 20°C for 30 minutes to obtain an aqueous solution in which tetracycline was completely degraded; the removal rate was calculated to be 97.4%.

[0042] In order to further study the effect of the composite material of cobalt slag and red mud and persulfate on degrading organic pollutants, the following experiments were conducted.

[0043] 1. Degradation effect on tetracycline

[0044] The method of Example 1 was used as the test group, and the same method as Example 1 was used except that potassium persulfate was not added. The remaining steps were the same as those of Example 1. As the control group 1, the same method as Example 2 was used except that Co 3 O 4 @Fe 2 O 3 The remaining steps were the same as those in Example 2 as Control Group 2. 2 mL of the suspension was taken at 1 min, 3 min, 5 min, 10 min, 20 min, and 30 min, respectively. After filtering through a 0.45 um filter head, the absorbance was tested on a spectrophotometer. The removal rate was calculated after conversion. The results are as follows: Figure 1 shown.

[0045] from Figure 1 As can be seen from the results, only adding Co 3 O 4 @Fe 2 O 3 The degradation effect of adding only potassium persulfate is lower than that of using Co in Example 1 of the present invention. 3 O 4 @Fe 2 O 3The degradation effect of tetracycline in combination with potassium persulfate solution indicates that Co 3 O 4 @Fe 2 O 3 It can effectively improve the degradation effect of tetracycline. Figure 1 It can be seen that after 5 minutes of reaction, the absorbance value tends to be stable, indicating that the degradation has been basically completed. 3 O 4 @Fe 2 O 3 and potassium persulfate can quickly degrade tetracycline.

[0046] 2. Degradation ability of catalysts obtained by mixing cobalt slag and red mud at different mass ratios

[0047] Co 3 O 4 It has a good degradation effect, but a large amount of metal ions are leached during the reaction process. The present invention reduces the leaching of metal ions while maintaining the degradation ability. In order to explore the effect of the materials obtained by mixing cobalt slag and red mud in different mass ratios on the degradation effect, the method of Example 1 was used to perform an activity test while keeping other conditions unchanged. 2 mL of the suspension was taken at 1 min, 3 min, 5 min, 10 min, 20 min, and 30 min respectively, and its absorbance was tested on a spectrophotometer after filtering with a 0.45 um filter head. The removal rate was calculated after conversion. The results are as follows Figure 2 shown.

[0048] from Figure 2 The results show that within a certain range, as Co 3 O 4 The mass is reduced, but the degradation ability is still good, and the absorbance tends to be stable within 5 minutes, the degradation is basically completed, and the degradation rate does not change much. It can be seen that the present invention can efficiently and quickly degrade tetracycline in water.

[0049] 3. Degradation effect on different organic pollutants

[0050] The method in Example 2 was used to degrade Congo red, tetracycline, doxycycline, methyl orange and acid fuchsin, respectively. 2 mL of the suspension was taken at 1 min, 3 min, 5 min, 10 min, 20 min and 30 min, respectively. The absorbance was tested on a spectrophotometer after filtering with a 0.45 um filter head. The removal rate was calculated after conversion. The results are as follows: Figure 3 shown.

[0051] from Figure 3The results show that within 0 to 2 minutes, the absorbance values ​​of Congo red, tetracycline, doxycycline, methyl orange and acid fuchsin all decreased significantly, indicating that Co 3 O 4 @Fe 2 O 3 It has a good degradation effect on Congo red, tetracycline, doxycycline, methyl orange and acid fuchsin. At 5 minutes, the absorbance values ​​of Congo red, tetracycline, doxycycline, methyl orange and acid fuchsin tend to be stable, indicating that the degradation process is basically completed. It can be seen that Co 3 O 4 @Fe 2 O 3 It has a good degradation effect on common antibiotics and dyes.

[0052] 4. Effect of different pH values ​​on Co 3 O 4 @Fe 2 O 3 Impact of degradation effects

[0053] The method in Example 1 was used to measure the effect of tetracycline degradation at pH values ​​of 3, 5, 7, and 9, respectively. 2 mL of the suspension was taken at 1 min, 3 min, 5 min, 10 min, 20 min, and 30 min, respectively. After filtering with a 0.45 um filter head, the absorbance was tested on a spectrophotometer. The removal rate was calculated after conversion. Figure 4 shown.

[0054] from Figure 4 The results show that pH has an important effect on Co 3 O 4 @Fe 2 O 3 The degradation effect of tetracycline was weakened under acidic conditions, and it promoted the degradation of tetracycline within 0 to 2 minutes under alkaline conditions and then gradually weakened.

[0055] 5. Degradation effect of tetracycline in actual water

[0056] The situation in actual water bodies is relatively complicated. In order to explore the influence of uncertain variables in actual water bodies on the degradation effect, the method in Example 1 was adopted, and tap water, Zhanhe River water, and Baigui Lake water from three different water bodies were used. 2 mL of the suspension was taken at 1 min, 3 min, 5 min, 10 min, 20 min, and 30 min, respectively. After filtering with a 0.45 um filter head, its absorbance was tested on a spectrophotometer, and its removal rate was calculated after conversion. The results are as follows: Figure 5 shown.

[0057] from Figure 5The results show that the uncertain variables in the actual water body will weaken the Co 3 O 4 @Fe 2 O 3 The specific impact should be analyzed based on actual conditions and may be related to water quality.

[0058] 6. Effects of common ions and free radicals in water on degradation

[0059] Using the method of Example 1, a certain amount of Cl - , CO 3 2- 、SO 4 2- , HPO 4 2- 、NO 3 - , take 2mL of suspension at 1min, 3min, 5min, 10min, 20min, and 30min respectively, filter it through a 0.45um filter head, and test its absorbance on a spectrophotometer. After conversion, calculate its removal rate result, such as Figure 6 shown.

[0060] from Figure 6 The results show that SO 4 2- 、NO 3 - It has little effect on tetracycline degradation. - , CO 3 2- , HPO 4 2- It will have a certain impact on the degradation effect of Co3O4@Fe2O3, which is manifested as a slight weakening of the degradation effect.

[0061] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for degrading organic pollutants, characterized in that: The following steps are involved: S1, mixing and grinding cobalt slag and red mud, and then roasting to obtain a composite material (Co3O4@Fe2O3) with cobalt and iron as main active components; S2, mixing the material obtained after roasting with persulfate to obtain a mixture; S3. Dispersing the mixture into a water body containing organic pollutants to be treated for degradation to obtain degraded water.

2. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The composite material is Co3O4@Fe2O3, the mass ratio of the cobalt slag to the red mud is 0.25-4; the mass ratio of the composite material to the persulfate is 0.3-2; and the dosage of the mixture is 0.01-0.8 g / L.

3. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The cobalt slag and red mud are roasted at a temperature of 300° C. to 800° C., the cobalt slag and red mud are roasted for a time of 2 h to 8 h, and the heating rate of the cobalt slag and red mud is 3 to 10° C. / min.

4. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The cobalt slag and red mud in the composite material are both common mineral wastes, which are widely available, low in price, and are solid wastes.

5. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The composite material has a particle size of 10 to 200 meshes.

6. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The persulfate is any one of potassium persulfate, sodium persulfate and potassium hydrogen persulfate.

7. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The degradation temperature is 15 to 30° C.; the degradation time is 5 to 60 minutes.

8. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The organic pollutant is any one or more of acid fuchsin, Congo red, methyl orange, tetracycline, doxycycline, and dibutyl phthalate.

9. A method for degrading organic pollutants as claimed in claim 1, characterized in that: The calcination atmosphere includes any one of air, carbon dioxide, nitrogen and ammonia.

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