Method for promoting cobalt sulfide loaded carbon composite catalyst to activate PMS degradation pollutants by using bicarbonate ions

Abstract

The invention discloses a method for promoting a cobalt sulfide loaded carbon composite catalyst to activate PMS to degrade pollutants by using bicarbonate ions. According to the method, bicarbonate radical ions are added into a system for degrading organic pollutants by activating the PMS with the cobalt sulfide loaded carbon composite catalyst, so that the efficiency of removing phenol by activating the PMS with the cobalt sulfide loaded carbon composite catalyst is greatly improved, and cobalt ion leaching is reduced due to addition of the bicarbonate radical ions; the cobalt sulfide loaded carbon composite catalyst has a wide application prospect in the field of advanced oxidation treatment of organic wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of advanced oxidation water treatment, and particularly relates to a method for utilizing bicarbonate ions to promote the activation of PMS by a cobalt sulfide-supported carbon composite catalyst to degrade pollutants. Background Art

[0002] Based on SO4 ·- Compared with the traditional Fenton reaction, the advanced oxidation technology has a higher redox potential, a longer reaction life, and can fully play its role under a wider pH water condition, so it is widely used to degrade water pollutants. ·- It is usually produced by activation with PDS or peroxymonosulfate (PMS), among which PMS is more easily activated due to its asymmetric structure; and cobalt-based catalysts are considered to be one of the most effective catalysts for activating PMS.

[0003] With the continuous development of society, various types of industrial wastewater, medical wastewater, and domestic sewage have gradually increased. These water bodies contain various inorganic salt ions, such as chloride, sulfate, phosphate, bicarbonate, etc. Therefore, researchers will simulate the sewage environment containing inorganic salt ions and study the degree of their impact on the catalytic activation of PMS to degrade pollutants. However, the conclusion is that compared with deionized water, these sewage containing inorganic salt ions will mostly inhibit the degradation of pollutants. However, in actual water treatment, sewage rich in inorganic salt ions is inevitable, so it is crucial to find a PMS degradation system that can more efficiently degrade organic pollutants in sewage containing certain inorganic salt ions. Summary of the Invention

[0004] In order to solve the problem that domestic sewage is rich in inorganic salt ions and most of these inorganic salt ions will inhibit the degradation efficiency of conventional catalysts to activate PMS to degrade organic pollutants, the present invention provides a method for using bicarbonate ions to promote the activation of PMS to degrade pollutants by cobalt sulfide-supported carbon composite catalysts.

[0005] The technical solutions of the present invention are as follows:

[0006] The method of using bicarbonate ions to promote the activation of PMS by cobalt sulfide-supported carbon composite catalyst to degrade pollutants is as follows: bicarbonate ions are added to the system of activating PMS by cobalt sulfide-supported carbon composite catalyst to degrade organic pollutants.

[0007] Furthermore, the specific method is: adding a cobalt sulfide-supported carbon composite catalyst to a solution containing organic pollutants, adding peroxymonosulfate and bicarbonate ions, and catalytically degrading the organic pollutants.

[0008] Furthermore, the cobalt sulfide-supported carbon composite catalyst is prepared by the following steps: soluble cobalt salt, polyethylene glycol 6000, and sodium thiosulfate are fully mixed and dissolved in water, and then carbon balls are added, uniformly dispersed, and then a hydrothermal reaction is carried out at 150-250° C. After the reaction is completed, the mixture is cooled to room temperature, repeatedly washed with ethanol and water, and centrifuged and dried to obtain the cobalt sulfide-supported carbon composite catalyst.

[0009] Preferably, in the above preparation process, the mass ratio of soluble cobalt salt, polyethylene glycol 6000, sodium thiosulfate, and carbon spheres is 1:1.4:2.2:0.15; the soluble cobalt salt is cobalt chloride hexahydrate; the hydrothermal reaction temperature is 200°C, and the hydrothermal reaction time is 12 hours.

[0010] Furthermore, the source of bicarbonate ions is sodium bicarbonate or potassium bicarbonate.

[0011] Furthermore, the amount of bicarbonate ions added is 5 mM or more, preferably 10 mM to 20 mM.

[0012] Furthermore, the organic pollutants include phenol, rhodamine B, methyl blue, and the like.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] (1) The present invention experimentally studies the influence of different inorganic salt ions on two catalytic degradation systems and unexpectedly finds that bicarbonate ions can greatly improve the efficiency of phenol removal by activating PMS with a cobalt sulfide-supported carbon composite catalyst, increasing the degradation rate from removing more than 90% of phenol within 10 minutes to removing more than 90% of phenol within 2 minutes.

[0015] (2) The present invention also found that in the system of activating PMS to remove organic pollutants using a cobalt sulfide-supported carbon composite catalyst, the addition of bicarbonate ions can also reduce cobalt ion leaching and improve the cyclic stability of the cobalt sulfide-supported carbon composite catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The effect of different concentrations of bicarbonate ions on the phenol degradation efficiency in the PMS degradation system activated by cobalt sulfide supported carbon composite catalyst;

[0017] Figure 2 This is the cyclic degradation diagram of the cobalt sulfide-supported carbon composite catalyst;

[0018] Figure 3 is the XRD pattern of the cobalt sulfide-supported carbon composite catalyst before and after phenol degradation under the action of bicarbonate ions;

[0019] Figure 4This paper studies the effects of different inorganic salt ions on the phenol degradation efficiency in the PMS degradation system activated by cobalt sulfide-supported carbon composite catalyst. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0021] The cobalt sulfide-supported carbon composite catalyst described herein was prepared with reference to existing literature. In the following examples, the cobalt sulfide-supported carbon composite catalyst was prepared using an existing method. Specifically, cobalt chloride hexahydrate, polyethylene glycol 6000, and sodium thiosulfate were thoroughly mixed and dissolved in water at a mass ratio of 1:1.4:2.2. Carbon spheres were then uniformly dispersed in the mixed solution at a mass ratio of carbon spheres to cobalt chloride hexahydrate of 0.15:1. The solution was then poured into a reactor, and the reactor was placed in an oven at 200°C for a hydrothermal reaction for 12 hours. After the reaction was complete, the mixture was cooled to room temperature, washed three times with ethanol and three times with water, and then centrifuged to dry, yielding the cobalt sulfide-supported carbon composite material.

[0022] The cobalt oxide-supported carbon composite material is prepared by an existing method, specifically: under ultrasonic treatment, cobalt nitrate hexahydrate and polyethylene glycol 6000 are fully dissolved in menthol at a mass ratio of 1:1.2, and then carbon balls: cobalt nitrate hexahydrate = 0.15:1 are uniformly dispersed in the above mixed solution, poured into a reactor, and hydrothermally reacted in an oven at 100-240°C for 12 hours. After the reaction is completed, it is cooled to room temperature, repeatedly washed with ethanol and water, and centrifuged to dry, finally obtaining the cobalt oxide-supported carbon composite material.

[0023] Comparative Example 1

[0024] 0.03g of the above cobalt sulfide-supported carbon composite catalyst was added to 100mL of 23.5mg / L phenol solution, followed by the addition of 2.5mM PMS to start the phenol degradation experiment. The results showed that it removed more than 90% of phenol in 10 minutes. Figure 1 As shown in the control group in.

[0025] Example 1

[0026] This example is similar to Comparative Example 1, except that 5 mM bicarbonate ions were added. The results showed that it could remove more than 90% of phenol in 2 minutes. Figure 1 shown.

[0027] Example 2

[0028] This example is similar to Comparative Example 1, except that 10 mM bicarbonate ions were also added. The results showed that it could remove more than 90% of phenol in 2 minutes. Figure 1 shown.

[0029] Example 3

[0030] This example is similar to Comparative Example 1, except that 20 mM bicarbonate ions were also added. The results showed that it could remove more than 90% of phenol in 2 minutes. Figure 1 shown.

[0031] Application Example 1

[0032] After the reaction in Example 1 was completed, the cobalt sulfide-supported carbon composite catalyst was recovered from the solution by centrifugal washing: the degradation experiment in Example 1 was repeated again, and the results showed that it could still remove more than 90% of phenol in 2 minutes; then the cobalt sulfide-supported carbon was recovered from the solution after the second degradation, and the degradation experiment in Example 1 was repeated, and it could still remove more than 90% of phenol in 5 minutes. Figure 2 The above results indicate that bicarbonate ions can effectively reduce the leaching of cobalt ions and improve the cyclic stability of the cobalt sulfide-supported carbon composite catalyst.

[0033] In summary, bicarbonate ions can not only greatly improve the efficiency of cobalt sulfide-supported carbon composite catalyst in activating PMS to degrade phenol, but also significantly enhance the effect of cobalt sulfide-supported carbon composite catalyst in activating PMS to degrade pollutants regardless of the high or low concentration of bicarbonate ions, but also effectively reduce cobalt ion leaching and improve the cyclic stability of cobalt sulfide-supported carbon composite catalyst.

[0034] Figure 3 Figure 3 is the XRD spectrum of the composite catalyst before and after phenol degradation under the action of bicarbonate ions. It can be seen that the peak intensity of the main diffraction peak 2θ=32.26℃ of the degraded cobalt sulfide-supported carbon composite catalyst is significantly higher than that of the unreacted cobalt sulfide-supported carbon composite catalyst. This result indicates that bicarbonate ions may improve the catalytic degradation effect of the composite catalyst by changing the crystal phase content of the composite catalyst.

[0035] Comparative Example 2

[0036] This comparative example is similar to Example 1, except that 5 mM chloride ions were also added. The results showed that only about 60% of phenol could be removed in 20 minutes. Figure 4 shown.

[0037] Comparative Example 3

[0038] This comparative example is similar to Example 1, except that 5 mM hydrogen phosphate ions were also added. The results showed that only about 80% of phenol could be removed in 20 minutes. Figure 4 shown.

[0039] Comparative Example 4

[0040] This comparative example is similar to Example 1, except that 5 mM nitrate ions were also added. The results showed that only about 60% of phenol could be removed in 20 minutes. Figure 4 shown.

[0041] Comparative Example 5

[0042] This comparative example is roughly the same as Example 1, except that the cobalt sulfide-supported carbon composite catalyst is replaced with a cobalt oxide-supported carbon composite catalyst. The results show that bicarbonate ions have a slight inhibitory effect on the cobalt oxide-supported carbon catalytic degradation system.

Claims

1. A method for utilizing bicarbonate ions to promote the activation of PMS by a cobalt sulfide-supported carbon composite catalyst to degrade pollutants, characterized in that: Bicarbonate ions are added to the system of PMS activated by cobalt sulfide supported carbon composite catalyst to degrade organic pollutants.

2. The method according to claim 1, characterized in that Specifically, a cobalt sulfide-loaded carbon composite catalyst is added to a solution containing organic pollutants, and peroxymonosulfate and bicarbonate ions are added to catalyze the degradation of the organic pollutants.

3. The method according to claim 1, characterized in that The cobalt sulfide-supported carbon composite catalyst is prepared by the following steps: soluble cobalt salt, polyethylene glycol 6000, and sodium thiosulfate are fully mixed and dissolved in water, and then carbon spheres are added, uniformly dispersed, and then a hydrothermal reaction is carried out at 150-250° C. After the reaction is completed, the mixture is cooled to room temperature, repeatedly washed with ethanol and water, and centrifuged and dried to obtain the cobalt sulfide-supported carbon composite catalyst.

4. The method according to claim 3, wherein The mass ratio of soluble cobalt salt, polyethylene glycol 6000, sodium thiosulfate, and carbon spheres is 1:1.4:2.2:0.15; the soluble cobalt salt is cobalt chloride hexahydrate; the hydrothermal reaction temperature is 200 °C, and the hydrothermal reaction time is 12 h.

5. The method according to claim 1, wherein The source of bicarbonate ions is sodium bicarbonate or potassium bicarbonate.

6. The method according to claim 1, wherein The amount of bicarbonate ions added is 5 mM or more.

7. The method according to claim 1, characterized in that The amount of bicarbonate ion added is 10mM~20mM.

8. The method according to claim 1, characterized in that The organic pollutants were phenol, rhodamine B or methylene blue.

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