Catalytic oxidation method of phenolic wastewater

Abstract

The invention discloses a catalytic oxidation method for phenolic wastewater. The catalytic oxidation method comprises the following steps: S1, preparing carbon nanotubes by utilizing a chemical deposition method; s2, taking Cu (NO3) 2.2. 5H2O as a precursor, doping the Cu (NO3) 2.2. 5H2O into the surface of the purified carbon nano tube through an impregnation method, drying, and calcining to obtain a CuO-loaded carbon nano tube; s3, taking Fe (NO3) 3.9 H2O as a precursor, doping the Fe (NO3) 3.9 H2O into the surface of the CuO-loaded carbon nanotube through an impregnation method, drying and calcining to obtain a CuO / Fe2O3-loaded carbon nanotube; and S4, carrying out oxidation treatment on the phenol-containing wastewater by taking the CuO / Fe2O3 loaded carbon nanotube as a catalyst and H2O2 as an oxidizing agent. According to the method, the CuO / Fe2O3 loaded carbon nano tube is used as a catalyst, H2O2 is used as an oxidizing agent to oxidize phenolic wastewater, a good catalytic oxidation effect is achieved when the pH is 3-7, and the degradation rate of phenolic substances is 98% or above.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a catalytic oxidation method for phenol-containing wastewater. Background Art

[0002] Phenolic compounds are an important chemical raw material and are widely used in the production of many commodities such as resins, nylon, plasticizers, antioxidants, polyesters, drugs, pesticides, explosives, dyes and gasoline additives. All these production activities inevitably produce various phenol-containing wastewaters.

[0003] As an advanced oxidation technology, the Fenton method is currently the most effective and widely used method for treating printing and dyeing wastewater. Its reaction reagents are composed of ferrous ions and hydrogen peroxide. The reaction will produce highly oxidizing hydroxyl radicals, which can degrade most organic pollutants into low-toxic, easily degradable small molecules, and even convert them into carbon dioxide and water. Even so, the Fenton method still has some unavoidable defects, which limit its further application. For example, (1) the pH adaptation range of the reaction is too narrow, and it can only work under strong acidic conditions of pH 2-3.5. When the pH is increased, there is basically no degradation effect. Therefore, weakly acidic, neutral and alkaline wastewater cannot be treated by the Fenton method; (2) the ferrous ions and ferric ions in the reaction are easy to form difficult-to-treat iron sludge as the reaction proceeds, causing secondary pollution. Summary of the invention

[0004] 1. Technical problem to be solved: The existing Fenton method has a narrow pH adaptation range and is prone to secondary pollution.

[0005] In view of the above technical problems, the present invention provides a catalytic oxidation method for phenol-containing wastewater.

[0006] 2. Technical solution: A catalytic oxidation method for phenol-containing wastewater comprises the following steps: S1: Carbon nanotubes were prepared by chemical deposition and further purified by oxidation, acid washing and water washing; S2: Cu(NO3)2·2.5H2O was used as a precursor and doped onto the surface of purified carbon nanotubes by an impregnation method, and then dried and calcined to obtain CuO-loaded carbon nanotubes; S3: Fe(NO3)3·9H2O was used as a precursor and doped into the surface of CuO-loaded carbon nanotubes by impregnation method, and then dried and calcined to obtain CuO / Fe2O3-loaded carbon nanotubes; S4: Phenol-containing wastewater is oxidized using CuO / Fe2O3-loaded carbon nanotubes as catalyst and H2O2 as oxidant.

[0007] Furthermore, in S2, the drying temperature is 60-100°C, the drying time is 10-12h, and after drying, it is first calcined at 120-180°C for 4-5h, and then continued to calcine at 400-500°C for 4-5h.

[0008] Furthermore, in S3, the drying temperature is 60-100°C, the drying time is 10-12h, and after drying, it is first calcined at 200-300°C for 4-5h, and then further calcined at 500-550°C for 4-5h.

[0009] Furthermore, the final loading of CuO in S2 is 3-5%, and the final loading of Fe2O3 in S3 is 3-5%.

[0010] Furthermore, the phenolic compounds in the phenol-containing wastewater include phenol, m-cresol and bisphenol A.

[0011] Furthermore, the content of phenolic compounds in the phenol-containing wastewater in S4 is 0.1-5 g / L.

[0012] Furthermore, the mass ratio of phenol-containing wastewater to catalyst in S4 is 1000:(1-3).

[0013] Furthermore, the concentration of hydrogen peroxide in S4 is 30%, and the volume ratio of hydrogen peroxide to phenol-containing wastewater is 1:10-12.

[0014] Furthermore, the reaction temperature of S4 is room temperature.

[0015] 3. Beneficial effects: The invention provides a catalytic oxidation method for phenol-containing wastewater. The carbon nanotubes loaded with CuO / Fe2O3 are used as catalysts and H2O2 is used as an oxidant to carry out oxidation treatment on the phenol-containing wastewater. The method has a good catalytic oxidation effect when the pH value is between 3 and 7, and the degradation rate of phenolic substances is above 98%. The method can be applicable to the treatment of various phenolic substances such as phenol, meta-cresol and bisphenol A, has strong applicability, is green and environmentally friendly, has stable properties, and is easy for secondary recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a line graph showing the degradation rates of phenol, m-cresol and bisphenol A as a function of the amount of catalyst; Figure 2 This is a line graph showing the degradation rates of phenol, m-cresol and bisphenol A as the pH of the system changes. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings.

[0018] Embodiment 1: A catalytic oxidation method for phenol-containing wastewater comprises the following steps: S1: Carbon nanotubes were prepared by chemical deposition and further purified by H2O2 oxidation, dilute hydrochloric acid washing and deionized water washing; S2: Take 4.4g Cu(NO3)2·2.5H2O, add it to 400mL deionized water, stir until it is completely dissolved, adjust the pH to 4, add 2g purified carbon nanotubes, soak at 50℃ for 24h, dry at 100℃ for 10h, calcine at 120℃ for 4h, heat to 450℃ and continue calcining for 4h to obtain CuO-loaded carbon nanotubes; S3: Take 10.0g Fe(NO3)3·9H2O as a precursor, add it to 400mL deionized water, stir until completely dissolved, adjust the pH to 4, add the CuO-loaded carbon nanotubes obtained in S2, soak at 50℃ for 24h, dry at 80℃ for 12h, calcine at 220℃ for 4h, heat to 520℃ and continue calcining for 4h to obtain CuO / Fe2O3-loaded carbon nanotubes; S4: Prepare 500 mL of wastewater containing phenol, m-cresol and bisphenol A respectively with a concentration of 3 g / L, add 0-1.5 g of CuO / Fe2O3-loaded carbon nanotubes as catalysts respectively, and then add 50 mL of H2O2 (30%), react at room temperature for 1.5 hours, and filter out the catalyst.

[0019] The degradation rate of phenolic substances in each group of experiments varies with the amount of catalyst and is shown in Table 1 and Figure 1 ; Table 1: Embodiment 2: A catalytic oxidation method for phenol-containing wastewater comprises the following steps: S1: Carbon nanotubes were prepared by chemical deposition and further purified by H2O2 oxidation, dilute hydrochloric acid washing and deionized water washing; S2: Take 4.4g Cu(NO3)2·2.5H2O, add it to 400mL deionized water, stir until it is completely dissolved, adjust the pH to 4, add 2g purified carbon nanotubes, soak at 60℃ for 24h, dry at 60℃ for 12h, calcine at 180℃ for 5h, heat to 500℃ and continue calcining for 4h to obtain CuO-loaded carbon nanotubes; S3: Take 10.0g Fe(NO3)3·9H2O as a precursor, add it to 400mL deionized water, stir until completely dissolved, adjust the pH to 4, add the CuO-loaded carbon nanotubes obtained in S2, soak at 60℃ for 24h, dry at 100℃ for 12h, calcine at 300℃ for 4h, heat to 550℃ and continue calcining for 4h to obtain CuO / Fe2O3-loaded carbon nanotubes; S4: Prepare 500mL of phenol-containing wastewater with a concentration of 3g / L, add 1.2g of CuO / Fe2O3-loaded carbon nanotubes as catalyst, then add 50mL H2O2 (30%), react at room temperature for 1.5h, filter out the catalyst, and the phenol degradation rate is 98.5%.

[0020] Embodiment 3: A catalytic oxidation method for phenol-containing wastewater comprises the following steps: S1: Carbon nanotubes were prepared by chemical deposition and further purified by H2O2 oxidation, dilute hydrochloric acid washing and deionized water washing; S2: Take 4.4g Cu(NO3)2·2.5H2O, add it to 400mL deionized water, stir until it is completely dissolved, adjust the pH to 4, add 2g purified carbon nanotubes, soak at 55℃ for 24h, dry at 120℃ for 10h, calcine at 160℃ for 4.5h, heat to 450℃ and continue calcining for 4.5h to obtain CuO-loaded carbon nanotubes; S3: Take 10.0g Fe(NO3)3·9H2O as a precursor, add it to 400mL deionized water, stir until completely dissolved, adjust the pH to 4, add the CuO-loaded carbon nanotubes obtained in S2, soak at 55℃ for 24h, dry at 110℃ for 12h, calcine at 200℃ for 4h, heat to 525℃ and continue calcining for 4h to obtain CuO / Fe2O3-loaded carbon nanotubes; S4: Prepare 500mL of phenol-containing wastewater with a concentration of 3g / L, add 1.2g of CuO / Fe2O3-loaded carbon nanotubes as catalyst, then add 50mL H2O2 (30%), react at room temperature for 1.5h, filter out the catalyst, and the phenol degradation rate is 98.4%.

[0021] Embodiment 4: Investigating the effect of pH on the reaction: From Example 1, it can be seen that 500 mL of phenolic wastewater (phenol, m-cresol and bisphenol A) with a concentration of 3 g / L is almost completely degraded when 1.2 g of CuO / Fe2O3-loaded carbon nanotubes are added as a catalyst. Therefore, the amount of the catalyst is the preferred appropriate amount. Keeping this amount, repeat S4, adjust the pH of the reaction system to 2-13 by hydrochloric acid and sodium hydroxide, respectively, and detect the degradation rate of phenolic substances. The results are shown in Table 2 and Figure 2 ; Table 2: It can be seen from Table 2 that the optimal pH range for treating phenol-containing wastewater with CuO / Fe2O3-loaded carbon nanotubes as catalyst is 3-7. Under alkaline conditions, the degradation rate of phenolic substances is significantly reduced.

[0022] Although the present invention has been disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims of this application.

Claims

1. A catalytic oxidation method for phenol-containing wastewater, characterized in that: The following steps are involved: S1: Carbon nanotubes were prepared by chemical deposition and further purified by oxidation, acid washing and water washing; S2: Cu(NO3)2·2.5H2O was used as a precursor and doped onto the surface of purified carbon nanotubes by an impregnation method, and then dried and calcined to obtain CuO-loaded carbon nanotubes; S3: Fe(NO3)3·9H2O was used as a precursor and doped into the surface of CuO-loaded carbon nanotubes by impregnation method, and then dried and calcined to obtain CuO / Fe2O3-loaded carbon nanotubes; S4: Phenol-containing wastewater is oxidized using CuO / Fe2O3-loaded carbon nanotubes as catalyst and H2O2 as oxidant.

2. The catalytic oxidation method for phenol-containing wastewater according to claim 1, characterized in that: In S2, the drying temperature is 60-100°C, the drying time is 10-12h, and after drying, it is first calcined at 120-180°C for 4-5h, and then continued to calcine at 400-500°C for 4-5h.

3. A catalytic oxidation method for phenol-containing wastewater according to claim 2, characterized in that: In S3, the drying temperature is 60-100°C, the drying time is 10-12h, and after drying, it is first calcined at 200-300°C for 4-5h, and then continued to calcine at 500-550°C for 4-5h.

4. The catalytic oxidation method for phenol-containing wastewater according to claim 3, characterized in that: The final loading of CuO in S2 is 3-5%, and the final loading of Fe2O3 in S3 is 3-5%.

5. A catalytic oxidation method for phenol-containing wastewater according to any one of claims 1 to 4, characterized in that: The phenolic compounds in the phenol-containing wastewater include phenol, m-cresol and bisphenol A.

6. The catalytic oxidation method for phenol-containing wastewater according to claim 5, characterized in that: The content of phenolic compounds in the phenol-containing wastewater in S4 is 0.1-5g / L.

7. The catalytic oxidation method for phenol-containing wastewater according to claim 6, characterized in that: The mass ratio of phenol-containing wastewater to catalyst in S4 is 1000:(1-3).

8. The catalytic oxidation method for phenol-containing wastewater according to claim 7, characterized in that: The concentration of hydrogen peroxide in S4 is 30%, and the volume ratio of hydrogen peroxide to phenol-containing wastewater is 1:10-12.

9. A catalytic oxidation method for phenol-containing wastewater according to any one of claims 6 to 8, characterized in that: The reaction temperature of S4 is room temperature.

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