CN106582875A - Activated carbon based composite catalyst for catalyzing persulfate to degrade dye methyl orange and preparation method thereof - Google Patents

Abstract

The invention relates to an activated carbon-based composite catalyst that catalyzes the degradation of dye methyl orange by persulfate, and is characterized in that the specific steps include: first loading tricobalt tetroxide on graphite oxide, and then compounding the graphite oxide loaded with tricobalt tetroxide with oxidized cellulose, Then compound the composite with activated carbon to prepare an activated carbon-based composite catalyst, and finally add potassium monopersulfate (PMS) to the water containing methyl orange to adjust the pH value, and add the activated carbon-based composite catalyst to degrade at a certain temperature. The catalyst of the present invention can be used at normal temperature and has a wide application range. This heterogeneous cobalt trioxide/graphite oxide/oxidized cellulose/activated carbon/PMS catalytic oxidation degradation system has the advantages of high catalytic efficiency, strong oxidation ability, and good reusability. , especially prominent is the strong adsorption capacity of the catalyst, high mechanical strength, after the reaction is completed, it can settle to the bottom of the waste water, which is easy to recycle, and can be used in the fields of sewage treatment and environmental governance.

Description

Activated carbon-based composite catalyst for catalyzing the degradation of dye methyl orange by persulfate and its preparation preparation method

technical field

The invention relates to a composite material used in the fields of sewage treatment, environmental treatment, etc., in particular to an activated carbon-based composite catalyst for catalyzing the degradation of dye methyl orange by persulfate and a preparation method thereof.

Background technique

Activated carbon has a well-developed microporous structure and special surface properties, but it can no longer meet the requirements of modern industrial development as an adsorbent alone to adsorb pollutants. Adjusting the pore structure of activated carbon and modifying the surface groups, such as the carrier of catalytic metal ions, can improve its special performance and specific adsorption and catalytic performance in the sewage and wastewater treatment process. Catalysts prepared by Li Weifeng and others with activated carbon loaded with Cu, Fe, Ni, Mn, etc. have a certain catalytic ability for the oxidation treatment of actual printing and dyeing wastewater (Li Weifeng, Zhu Shemin, Song Tianshun, Chen Yingwen, Shen Shubao. Catalytic oxidation treatment of printing and dyeing by metal-loaded activated carbon Wastewater [J]. Journal of Nanjing University of Technology 2006.7, 5-8). Yu Moxin and others studied that Ag ⁺ , Ni ²⁺ , Cu ²⁺ or Zn ²⁺ ions loaded on the surface of activated carbon can improve the ability of activated carbon to adsorb benzothiophene sulfide (Yu Moxin, Li Zhong, Xia Qibin, Xi Hongxia. Surface loading of activated carbon Effect of metal ions on its adsorption of benzothiophene [J]. Acta Chemical Industry Sinica 2006.8.1943-1948).

PMS is also known as potassium hydrogen persulfate compound salt, which can produce SO4 under the conditions of transition metals, heating or ultraviolet light ^- (Beitz T., Bechmann W., Mitzner R. Investigations of reactions of selectedazaarenes with redicals in Water.1.Hydroxyl and sulfurateradicals.J.Phys.Chem.A., 1998,102(34):6760-6765) and are widely used in environmental treatment.

Contents of the invention

The problem to be solved by the present invention is to provide an activated carbon-based composite catalyst that catalyzes persulfate to degrade the dye methyl orange. It is more convenient to use.

In order to solve the above problems, the invention provides a preparation method of an activated carbon-based composite catalyst that catalyzes the degradation of dye methyl orange by persulfate, which is characterized in that, first, three cobalt tetroxide is loaded onto graphite oxide, and then the graphite oxide loaded with three cobalt tetroxide and Oxidize cellulose and compound, then compound the compound with activated carbon to prepare an activated carbon-based composite catalyst, and finally add potassium monopersulfate (PMS) to the water containing methyl orange to adjust the pH value, and then add activated carbon-based composite catalyst for degradation.

Preferably, the preparation method of described activated carbon-based composite catalyst is:

Step 1: Add graphite oxide powder to n-hexanol, and make it into a uniformly dispersed suspension by ultrasonication, and dissolve cobalt nitrate hexahydrate in another part of n-hexanol to form a red solution and mix with graphite oxide The suspension was mixed and stirred at room temperature to mix the two substances evenly, and then the mixture was heated at reflux at 140°C for 12h. After the reaction, the reaction system was cooled to room temperature, washed by centrifugation, and washed repeatedly with ethanol to remove n-hexane Alcohol and sundries therein, and finally the obtained product is dried in a vacuum oven at 60°C for later use;

The second step: the sodium hydroxide/thiourea/urea solution is stirred at low temperature at high speed to dissolve the oxidized cellulose to obtain a transparent oxidized cellulose solution, and then the product is centrifuged at a high speed to remove insoluble matter and air bubbles, and the tricobalt tetroxide/graphite oxide composite The powder is ultrasonically dispersed for 1 hour, mixed evenly with the cellulose solution, and then mixed with activated carbon, and the final mixed slurry is filtered with a polytetrafluoroethylene membrane, and the pH is adjusted to neutral with hydrochloric acid before filtration, at 60°C in the air Drying for 12 hours under the hood to obtain the activated carbon-based composite catalyst.

Preferably, the added amount of potassium monopersulfate is 0.4-10m·mol/L.

Preferably, the added amount of the activated carbon-based composite catalyst is 0.8-1.6 g/L.

Preferably, the pH value is 4-10.

Preferably, the degradation temperature is 15-60° C.; the degradation time is 2-14 minutes.

Preferably, the initial concentration of methyl orange is 0.1-1 m·mol/L.

Preferably, the added amount of potassium monopersulfate is 2m·mol/L; the added amount of activated carbon-based composite catalyst is 1.2g/L; the pH value is 7; the degradation temperature is 25°C, and the degradation time is 8min; The initial concentration of methyl orange is 0.2m·mol/L. Under the combination of the treatment conditions, the treatment efficiency is better, and the removal rate of methyl orange is over 99.5%.

The present invention also provides an activated carbon-based composite catalyst for catalyzing the degradation of methyl orange by persulfate prepared by the method for preparing the above-mentioned activated carbon-based composite catalyst for catalyzing the degradation of methyl orange by persulfate.

Preferably, the mass content of activated carbon in the activated carbon-based composite catalyst is 83.33%.

The present invention adopts heterogeneous cobalt tetroxide/graphite oxide/oxidized cellulose/activated carbon/PMS catalytic oxidation degradation system: active carbon is used as carrier, loaded cobalt tetroxide/graphite oxide/oxidized cellulose is used as catalyst, and PMS is the system of oxidant to methyl orange dye Catalyzed oxidative degradation.

With the increase of PMS concentration, more SO ₄ ^- · can be produced to degrade methyl orange dye wastewater, so the higher the PMS concentration, the faster the degradation of methyl orange dye wastewater, but when the PMS concentration increases to a certain amount, Further increasing the concentration of PMS, while increasing the treatment cost, the degradation rate of methyl orange dye wastewater is not obvious, taking into account both cost and treatment efficiency, the most preferred is 2m·mol/L.

With the increase of catalyst amount, there are more catalytic active sites in the reaction system to catalyze PMS and generate more SO ₄ ^- · to degrade methyl orange dye wastewater, so the more catalyst dosage, the methyl orange dye wastewater faster degradation rate. But when the amount of catalyst is increased to a certain amount, and then increase the amount of catalyst, the degradation rate of methyl orange dye wastewater does not increase significantly, taking into account cost and treatment efficiency, the most preferred is 1.2g/L.

Studies have shown that the advanced oxidation technology based on sulfate radicals is an endothermic reaction, and increasing the temperature can significantly increase the reaction rate. However, increasing the temperature increases energy consumption, which in turn increases processing costs. Experiments have shown that when the degradation reaction is carried out at room temperature, the degradation rate is very high, so 25° C. is the most preferred.

The invention uses PMS as an oxidant and an activated carbon-based compound as a catalyst to degrade the dye methyl orange, and the catalyst has good adsorption performance and catalytic performance, good reusability and easy recovery.

Compared with prior art, the beneficial effect of the present invention is:

The catalyst of the present invention can be used at normal temperature and has a wide application range. This heterogeneous cobalt trioxide/graphite oxide/oxidized cellulose/activated carbon/PMS catalytic oxidation degradation system has the advantages of high catalytic efficiency, strong oxidation ability, and good reusability. , especially prominent is that the catalyst has good adsorption performance and high density, and can settle to the bottom of the waste water after the reaction is completed, which is convenient for recycling.

Description of drawings

Fig. 1 is the data analysis diagram of different oxidant dosages to described waste water degradation effect among the embodiment 2;

Fig. 2 is the data analysis diagram of different temperature treatment temperature to described waste water degradation effect in embodiment 3;

Fig. 3 is the data analysis diagram of different catalyst dosages to described waste water degradation effect in embodiment 4;

Fig. 4 is a data analysis diagram of the wastewater degradation effect of the catalyst recycled six times in Example 5.

detailed description

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

Example 1

Add 200 mg of graphite oxide powder into n-hexanol (120 mL), and form a uniformly dispersed suspension by ultrasonication for 2 h, and dissolve 1 mmol of cobalt nitrate hexahydrate (calculated as 0.291 g based on a relative molecular mass of 291.03) in another In n-hexanol (80 mL), a red solution was formed, mixed with the suspension containing graphite oxide, and stirred at room temperature for 0.5 h to mix the two substances uniformly. The mixture was then heated at reflux at 140 °C for 12 h. After the reaction, the reaction system was cooled to room temperature, centrifuged and washed (centrifuge speed test adjustment), and repeatedly washed with ethanol to remove n-hexanol and impurities therein, and finally the obtained product was dried in a vacuum oven at 60°C for use.

Sodium hydroxide, urea, and deionized water were configured into 100 g of a mixed solution at a mass ratio of 7:12:79, and 2 g of oxidized cellulose was added to it after cooling at -10°C for 3 hours, while rotating at 16,000 rpm/min. After stirring rapidly for 5 minutes, continue to stir at a slow speed for 2 hours to fully dissolve the oxidized cellulose, and then obtain a transparent oxidized cellulose solution, continue to stir and slowly rise to room temperature, and then centrifuge the product at 8,000rpm for 10 minutes to remove insolubles and bubbles to obtain an oxidized cellulose solution with a mass fraction of about 2%. The product is stored at low temperature (below 10°C) for future use.

Slowly add 5g of the above-mentioned transparent oxidized cellulose solution to 6.25mL Co ₃ O ₄ /GO (4mg/mL) suspension, stir evenly and ultrasonically for 10min to fully mix, then stir the mixture rapidly at 16,000rpm/min for 30min , and continued to stir at a slow speed for 8h to obtain a uniformly colored black slurry. Take 10 g of black slurry, add 50 g of activated carbon, stir and mix for 3 hours, then filter with a polytetrafluoroethylene membrane, adjust the pH to neutral with hydrochloric acid before filtering, and dry at 60°C in the air for 12 hours to obtain Co3 with a mass ratio of 1: ₅ O ₄ /GO/oxidized cellulose/activated carbon composite catalyst.

Example 2

Add 100mL of prepared 0.2m·mol/L methyl orange solution into five reactors, add 0.4m·mol, 1m·mol, 2m·mol, 4m·mol, 6m·mol, 10m·mol mol of PMS, then use the NaHCO of 0.5mol/ _L buffer solution to adjust the pH value of the solution to 7, all add the active carbon-based composite catalyst made in 0.12g embodiment 1 in each conical flask, put the conical flask Adjust the temperature to 25°C on the constant temperature water bath shaker, shake at a constant temperature at a certain speed, and start timing, sample 5mL at regular intervals, mix with an equal volume of quencher methanol solution to terminate the reaction, and then filter. Finally, UV-7504 spectrophotometer was used to measure the corresponding absorbance of the solution at 486nm. Each experiment was repeated three times to obtain the average value. The reaction result (C/C ₀ represents the current concentration compared to the initial concentration) is shown in Figure 1, indicating that the amount of oxidant added can greatly affect the degradation effect, and the larger the added amount, the faster the degradation rate. Finally, taking into account the cost and treatment efficiency, the choice of The optimal amount of oxidant added is 2m·mol.

Example 3

All add 100mL prepared 0.2m·mol/L methyl orange solution in four reactors, according to the result of embodiment 2, each Erlenmeyer flask is all added the PMS of 2m·mol, then use 0.5mol/L 1L _of NaHCO Buffer solution to adjust the pH value of the solution to 7, add 0.12g of the activated carbon-based composite catalyst prepared in Example 1 to each conical flask, and place the conical flask on a constant temperature water bath shaker to adjust the temperature At 15°C, 25°C, 40°C, 60°C, shake at a constant temperature at a certain rate, and start timing, sample 5mL at regular intervals, mix with an equal volume of quencher methanol solution to terminate the reaction, and then filter. Finally, UV-7504 spectrophotometer was used to measure the corresponding absorbance of the solution at 486nm. Each experiment was repeated three times to obtain the average value. The reaction result (C/C ₀ represents the current concentration compared to the initial concentration) is shown in Figure 2, which shows that the temperature can greatly affect the degradation effect, and the higher the temperature, the faster the degradation rate. Finally, considering the cost and treatment efficiency, the best treatment is selected The temperature is 25°C.

Example 4

All add 100mL prepared 0.2m·mol/L methyl orange solution in four reactors, according to the result of embodiment 2 and example 3, each Erlenmeyer flask all adds the PMS of 2m·mol, then uses _The NaHCO buffer solution of 0.5mol/L adjusts the pH value of the solution to 7, and in each conical flask, respectively add 0.08g, 0.1g, 0.12g, 0.14g, 0.16g of the activated carbon base prepared in Example 1 Composite catalyst, put the Erlenmeyer flask on a constant temperature water bath shaker, adjust the temperature to 25°C, shake at a constant temperature at a certain rate, and start timing, sample 5mL at regular intervals, and mix it with an equal volume of quencher methanol solution , to terminate the reaction, followed by filtration. Finally, UV-7504 spectrophotometer was used to measure the corresponding absorbance of the solution at 486nm. Each experiment was repeated three times to obtain the average value. The reaction results (C/C ₀ represents the current concentration compared to the initial concentration) are shown in Figure 3, indicating that the amount of catalyst added can greatly affect the degradation effect, and the greater the amount added, the faster the degradation rate. Finally, taking into account the cost and processing efficiency, the choice of The optimal amount of catalyst added is 1.2g/L.

Example 5

All add 100mL prepared 0.2m·mol/L methyl orange solution in six reactors, according to the result of embodiment 2 and example 3, each Erlenmeyer flask all adds the PMS of 2m·mol, then use 0.5mol/L _NaHCO3 buffer solution adjusts the pH value of the solution to 7, respectively adds the activated carbon-based composite catalyst prepared in Example 1 of 0.12g in each conical flask, and puts the conical flask into a constant temperature water bath for oscillation Adjust the temperature on the device to 25°C, oscillate at a constant temperature at a certain rate, and start timing. Take 5 mL of a sample from one of the conical flasks at regular intervals, and mix it with an equal volume of quencher methanol solution to terminate the reaction. , followed by filtering. Finally, UV-7504 spectrophotometer was used to measure the corresponding absorbance of the solution at 486nm. After the reaction, the catalysts of each parallel reaction were collected, and then centrifuged, washed with ethanol, vacuum dried, etc. to obtain dry and pure catalysts, and then re-weighed 0.12g each and added to five Erlenmeyer flasks for subsequent cyclic reactions. , so cycle 5 times. Weigh 0.12g catalyst for the last time and only add to one Erlenmeyer flask, and the other steps are the same as above. The reaction result (C/C ₀ represents the current concentration compared to the initial concentration) is shown in Figure 4. After 5 cycles, Acid Orange II can still achieve 100% degradation effect in a short period of time, indicating that the catalyst remains stable after repeated use. High catalytic activity is maintained, and complete degradation can still be completed within 14 minutes.

Claims (10)

1. a kind of preparation method of the gac-based composite catalyst of catalyzed persulfate degradation dye methyl orange, it is characterized in that, three cobalt tetroxide is loaded on the graphite oxide earlier, then the graphite oxide and cellulose oxide of load three cobalt tetroxide are compounded, then The composite is combined with activated carbon to prepare an activated carbon-based composite catalyst, and finally potassium monopersulfate is added to the water containing methyl orange to adjust the pH value, and then the activated carbon-based composite catalyst is added for degradation. 2. the preparation method of the activated carbon-based composite catalyst of catalyzing persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, the preparation method of described activated carbon-based composite catalyst is: Step 1: Add graphite oxide powder to n-hexanol, and make it into a uniformly dispersed suspension by ultrasonication, and dissolve cobalt nitrate hexahydrate in another part of n-hexanol to form a red solution and mix with graphite oxide The suspension was mixed and stirred at room temperature to mix the two substances evenly, and then the mixture was heated at reflux at 140°C for 12h. After the reaction, the reaction system was cooled to room temperature, washed by centrifugation, and washed repeatedly with ethanol to remove n-hexane Alcohol and sundries therein, and finally the obtained product is dried in a vacuum oven at 60°C for later use; The second step: the sodium hydroxide/thiourea/urea solution is stirred at low temperature at high speed to dissolve the oxidized cellulose to obtain a transparent oxidized cellulose solution, and then the product is centrifuged at a high speed to remove insoluble matter and air bubbles, and the tricobalt tetroxide/graphite oxide composite The powder is ultrasonically dispersed for 1 hour, mixed evenly with the cellulose solution, and the mixed solution is mixed with activated carbon again, and the final mixed slurry is filtered with a polytetrafluoroethylene membrane, and the pH is adjusted to neutral with hydrochloric acid before filtering. After drying for 12 hours, the activated carbon-based composite catalyst is obtained. 3. the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, the add-on of described potassium monopersulfate is 0.4-10m mol/L. 4. the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, the add-on of described activated carbon-based composite catalyst is 0.8-1.6g/L. 5. the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, described pH value is 4-10. 6. the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, the temperature of described degradation is 15-60 ℃; Degradation time is 2-14min. 7. the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, the initial concentration of described methyl orange is 0.1-1m·mol/L. 8. the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange as claimed in claim 1, is characterized in that, the add-on of described potassium monopersulfate is 2m mol/L; The dosage of the composite catalyst was 1.2g/L; the pH value was 7; the degradation temperature was 25°C, and the degradation time was 8min; the initial concentration of methyl orange in water was 0.2m·mol/L. 9. a kind of activated carbon-based composite catalyst of the catalytic persulfate degradation dye methyl orange that adopts the preparation method of the preparation method of the activated carbon-based composite catalyst of catalytic persulfate degradation dye methyl orange described in any one of claim 1-8. 10. the activated carbon-based composite catalyst of catalyzing persulfate degradation dye methyl orange as claimed in claim 9, is characterized in that, the mass content of activated carbon in the described activated carbon-based composite catalyst is 83.33%.