A photocatalyst, a preparation method thereof and application of sodium anthraquinone-2-sulfonate in promoting degradation of azo dyes by the photocatalyst

Abstract

The application belongs to the technical field of sewage treatment, and provides a photocatalyst, a preparation method thereof, and application of sodium anthraquinone-2-sulfonate in promoting degradation of azo dyes by the photocatalyst. The preparation method of the photocatalyst comprises the following steps: reacting Bi(NO3)3.5H2O, TaCl5 and ethylene glycol to obtain Bi7Ta3O 18 ; calcining bimelamine to obtain g-C3N4; and calcining Bi7Ta3O 18 and g-C3N4 to obtain the photocatalyst Bi7Ta3O 18 / g-C3N4. In the application, Bi7Ta3O 18 serves as an oxidizing photocatalyst, g-C3N4 serves as a reducing photocatalyst, an S-type heterojunction is synthesized, recombination of e ‑ and h + is inhibited, and the degradation rate of azo dyes is improved; and the sodium anthraquinone-2-sulfonate and the photocatalyst cooperate with each other to accelerate the reaction process of the photocatalyst in degrading azo dyes.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewage treatment technical field, and particularly relates to a photocatalyst, a preparation method thereof and application of sodium anthraquinone-2-sulfonate in promoting degradation of azo dyes by the photocatalyst. BACKGROUND

[0002] Printing and dyeing industry is one of the industries with high use rate of various dyes. With the development of the printing and dyeing industry, new dye products and dye production gradually increase, and the amount of dye wastewater discharged is increasing, which has become one of the main sources of water pollution. The organic matters in dye wastewater are complex in composition and different in nature, and most of them have characteristics such as high concentration, deep color, difficult degradation and strong biological toxicity. Azo dyes are the largest class of dyes, accounting for about 70% of all dyes. The precursors and degradation products of azo dyes, aromatic amines, have great toxicity and teratogenic and carcinogenic properties, and the complex composition and chemical structure will increase the complications. Therefore, the decolorization and degradation of azo dyes with wide application and complex structure have attracted much attention.

[0003] At present, the treatment methods of printing and dyeing wastewater mainly include physical method, chemical method and biological method. The chemical method, which is the preferred method of photocatalytic oxidation, uses some semiconductor photocatalytic materials to generate ·OH, ·O2 - and other high activity groups under the excitation of light at different wavelengths, and realizes the ring opening and chain breaking of organic matters through catalytic oxidation, so as to achieve the purpose of degrading dyes. However, the efficiency of photocatalytic oxidation in degrading dyes is low, and the rapid recombination of photo-generated electron pairs in the process of photocatalytic oxidation has always been the main bottleneck restricting the degradation of dyes by photocatalytic oxidation.

[0004] In order to improve the efficiency of photocatalytic oxidation in degrading dyes, heterojunction photocatalysts have gradually attracted widespread attention. S-type heterojunction is composed of oxidation-type photocatalyst (OP) and reduction-type photocatalyst (RP), which are interwoven through energy band structure. Once the two materials are in contact, the e - on the conduction band (CB) of RP and the h + on the valence band (VB) of OP are reserved, and the small recombination of photo-generated carriers makes the heterojunction photocatalyst still maintain strong redox potential, thereby improving the efficiency of degrading dyes.

[0005] Anthraquinone is used as an electron medium to promote electron transfer, accelerate electron transfer from the reducing agent to the azo dye in the degradation process, avoid steric hindrance of the dye molecule, and greatly improve the efficiency of anaerobic decolorization of azo dye wastewater. At present, anthraquinone electron medium has been reported to have obvious promoting effect in the degradation of azo dyes in biological system, such as sodium anthraquinone-2-sulfonate, disodium anthraquinone-2, 6-disulfonate, menadione, 2-hydroxy-1, 4-naphthoquinone, etc. However, there are few reports on whether anthraquinone electron medium can promote photocatalytic oxidation degradation of azo dyes. Therefore, it has good prospects to study the role of anthraquinone electron medium in photocatalytic oxidation degradation of azo dyes. SUMMARY

[0006] The purpose of the present application is to provide a photocatalyst, a preparation method thereof and the application of sodium anthraquinone-2-sulfonate in promoting photocatalyst degradation of azo dyes in view of the deficiencies of the prior art.

[0007] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0008] The present application provides a preparation method of a photocatalyst, comprising the following steps:

[0009] 1) mixing Bi(NO3)3·5H2O, TaCl5 and ethylene glycol and then reacting to obtain Bi7Ta3O 18 ;

[0010] g-C3N4 is obtained by calcining bimelamine;

[0011] 2) mixing Bi7Ta3O 18 and g-C3N4 and then calcining to obtain a photocatalyst Bi7Ta3O 18 / g-C3N4.

[0012] Preferably, the mass-volume ratio of Bi(NO3)3·5H2O, TaCl5 and ethylene glycol in step 1) is 3-3.5 mg: 0.8-1.2 mg: 10-12 mL; the reaction temperature is 180-220℃, the reaction time is 20-28h, and the pH value of the reaction is 10-11; the calcination temperature is 500-600℃, and the calcination time is 3-5h.

[0013] Preferably, the calcination temperature in step 2) is 350-450℃, and the calcination time is 0.5-1.5h.

[0014] Preferably, the mass fraction of Bi7Ta3O 18 in the photocatalyst Bi7Ta3O 18 / g-C3N4 in step 2) is 5-80%.

[0015] The present invention also provides a photocatalyst prepared by the aforementioned photocatalyst preparation method.

[0016] The present invention also provides the use of sodium anthraquinone-2-sulfonate in promoting the degradation of azo dyes by the aforementioned photocatalyst.

[0017] Preferably, the azo dye comprises one or more of Reactive Red, Methyl Orange, Congo Red, Acid Orange, and Sudan Red, and the concentration of the azo dye is 20–100 mg / L.

[0018] Preferably, the mass-to-volume ratio of the photocatalyst, sodium anthraquinone-2-sulfonate, and azo dye is 80–480 mg: 1.5–9.3 mg: 200–300 mL.

[0019] The beneficial effects of this invention include the following:

[0020] 1) This invention utilizes Bi7Ta3O 18 As an oxidation-type photocatalyst (OP), g-C3N4 was used as a reduction-type photocatalyst (RP) to synthesize the S-type heterojunction composite photocatalyst Bi7Ta3O. 18 / g-C3N4 effectively suppresses e-waves in the conduction band of g-C3N4. - and Bi7Ta3O 18 h on the valence band and energy band + The combination of these components promotes redox reactions and increases the degradation rate of azo dyes.

[0021] 2) In the presence of the photocatalyst Bi7Ta3O of the present invention 18 Sodium anthraquinone-2-sulfonate was added to the / g-C3N4 azo dye solution, and sodium anthraquinone-2-sulfonate reacted with the photocatalyst Bi7Ta3O 18 The interaction between / g-C3N4 and the photocatalyst Bi7Ta3O accelerates the process. 18 The reaction process of / g-C3N4 degrades azo dyes, resulting in a degradation rate of up to 94.54%, which is significantly better than the degradation rate without the addition of sodium anthraquinone-2-sulfonate (the removal rate without the addition of sodium anthraquinone-2-sulfonate is only 85.87%). Attached Figure Description

[0022] Figure 1 For different mass fractions of Bi7Ta3O 18 Photocatalyst Bi7Ta3O 18 / g-C3N4's effect on degrading Congo red.

[0023] Figure 2 To add different amounts of sodium anthraquinone-2-sulfonate to the photocatalyst Bi7Ta3O 18 The effect of / g-C3N4 on the degradation of Congo red.

[0024] Figure 3 Bi7Ta3O 18 A process mechanism diagram for degradation of Congo red by g-C3N4 photocatalyst Bi7Ta3O DETAILED DESCRIPTION

[0025] The application provides a preparation method of a photocatalyst.

[0026] 1) mixing Bi(NO3)3.5H2O, TaCl5 and ethylene glycol and then reacting to obtain Bi7Ta3O 18 ;

[0027] The bicyanamide is calcined to obtain g-C3N4.

[0028] 2) mixing Bi7Ta3O 18 and g-C3N4 and then calcining to obtain the photocatalyst Bi7Ta3O 18 / g-C3N4.

[0029] In the application, the mass-volume ratio of Bi(NO3)3.5H2O, TaCl5 and ethylene glycol in step 1) is preferably 3-3.5 mg: 0.8-1.2 mg: 10-12 mL, further preferably 3.2-3.5 mg: 0.9-1.1 mg: 10-11 mL, and more preferably 3.4 mg: 1.07 mg: 10 mL; the reaction temperature is preferably 180-220 DEG C, further preferably 190-210 DEG C, and more preferably 200 DEG C; the reaction time is preferably 20-28 h, further preferably 22-26 h, and more preferably 24 h; and the pH value of the reaction is preferably 10-11, and further preferably 10.5; the calcination temperature is preferably 500-600 DEG C, and further preferably 550 DEG C; and the calcination time is preferably 3-5 h, and further preferably 4 h.

[0030] In the application, the mixing in step 1) is preferably ultrasonic mixing, and the ultrasonic mixing frequency is preferably 20-50 kHz, and further preferably 30-40 kHz; and the ultrasonic mixing time is preferably 20-40 min, and further preferably 30 min.

[0031] In the application, the pH value of the mixing system is adjusted by using a potassium hydroxide solution in step 1), and the concentration of the potassium hydroxide solution is preferably 7 mol / L.

[0032] In the application, the calcination temperature in step 2) is preferably 350-450 DEG C, and further preferably 400 DEG C; and the calcination time is preferably 0.5-1.5 h, and further preferably 1 h.

[0033] In the present application, the photocatalyst Bi7Ta3O 18 The mass fraction of Bi7Ta3O 18 in the g-C3N4 is preferably 5-80%, further preferably 10-60%, and more preferably 20-40%.

[0034] The present application also provides a photocatalyst prepared by the preparation method of the photocatalyst.

[0035] The present application also provides the use of sodium anthraquinone-2-sulfonate in promoting the degradation of azo dyes by the photocatalyst.

[0036] In the present application, the azo dye preferably comprises one or more of Reactive Red, Methyl Orange, Congo Red, Acid Orange and Sudan Red, and the concentration of the azo dye is preferably 20-100 mg / L, further preferably 30-80 mg / L, and more preferably 50 mg / L.

[0037] In the present application, the mass-volume ratio of the photocatalyst, sodium anthraquinone-2-sulfonate and azo dye is preferably 80-480 mg: 1.5-9.3 mg: 200-300 mL, further preferably 100-400 mg: 3.87-7.75 mg: 220-280 mL, and more preferably 200-300 mg: 5-6 mg: 250-260 mL.

[0038] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.

[0039] Example 1

[0040] 3.4 mg of Bi(NO3)3·5H2O and 1.07 mg of TaCl5 were added to 10 mL of ethylene glycol, and a mixed solution was obtained by ultrasonic mixing at a frequency of 30 kHz for 30 min. A potassium hydroxide solution with a concentration of 7 mol / L was used to adjust the pH value of the mixed solution to 10.5, and the mixed solution was moved to a high-pressure reaction kettle, and a yellow precipitate product Bi7Ta3O 18 was obtained by reacting at 200℃ for 24 h.

[0041] Bimolecular cyanamide was calcined in a muffle furnace at 550℃ for 4 h to obtain yellow powder g-C3N4.

[0042] Bi7Ta3O 18 and g-C3N4 with a mass ratio of 5:95 were placed in a muffle furnace and calcined at 400℃ for 1 h to obtain a photocatalyst, which is denoted as 5wt%Bi7Ta3O 18 / g-C3N4.

[0043] Example 2

[0044] Bi7Ta3O 18 and g-C3N4 with a mass ratio of 10:90, and other same as example 1, the obtained photocatalyst is recorded as 10wt% Bi7Ta3O 18 / g-C3N4.

[0045] Example 3

[0046] Bi7Ta3O 18 and g-C3N4 with a mass ratio of 20:80, and other same as example 1, the obtained photocatalyst is recorded as 20wt% Bi7Ta3O 18 / g-C3N4.

[0047] Example 4

[0048] Bi7Ta3O 18 and g-C3N4 with a mass ratio of 80:20, and other same as example 1, the obtained photocatalyst is recorded as 80wt% Bi7Ta3O 18 / g-C3N4.

[0049] Example 5

[0050] 3.2mg Bi(NO3)3·5H2O and 0.9mg TaCl5 were added to 11mL ethylene glycol, and a mixed solution was obtained by ultrasonic mixing at a frequency of 40kHz for 20min, a potassium hydroxide solution with a concentration of 7mol / L was used to adjust the pH value of the mixed solution to 10, and the mixed solution was moved to a high-pressure reaction kettle, and a yellow precipitate product Bi7Ta3O 18 was obtained by reacting at 190℃ for 26h.

[0051] Melamine was placed in a muffle furnace and calcined at 500℃ for 5h to obtain a yellow powder g-C3N4.

[0052] Bi7Ta3O 18 and g-C3N4 with a mass ratio of 10:90 were placed in a muffle furnace and calcined at 350℃ for 1.5h to obtain a photocatalyst, which is recorded as 10wt% Bi7Ta3O 18 / g-C3N4.

[0053] Example 6

[0054] Bi(NO3)3·5H2O and 1.1 mg of TaCl5 were added to 12 mL of ethylene glycol, and a mixed solution was obtained by ultrasonic mixing at a frequency of 20 kHz for 40 min. The pH value of the mixed solution was adjusted to 11 using a potassium hydroxide solution with a concentration of 7 mol / L. The mixed solution was moved to a high-pressure reaction kettle, and a yellow precipitate product Bi7Ta3O 18 ;

[0055] The bimelamine was calcined in a muffle furnace at 600 DEG C for 3 h to obtain a yellow powder g-C3N4.

[0056] The Bi7Ta3O 18 and g-C3N4 with a mass ratio of 10:90 were placed in a muffle furnace and calcined at 450 DEG C for 0.5 h to obtain a photocatalyst, which was recorded as 10wt%Bi7Ta3O 18 / g-C3N4.

[0057] 100 mg of the photocatalyst prepared in each of Examples 1 to 4 was added to 250 mL of a Congo red solution with a concentration of 50 mg / L to obtain mixed solutions 1 to 4, respectively. The mixed solutions 1 to 4 were irradiated under a halogen lamp (220 V, 300 W) light source for 72 h. Every 12 h, 8 mL of the mixed solution was removed from each of the mixed solutions 1 to 4 and placed in a centrifuge, which was centrifuged at a speed of 1000 rpm for 100 min. The supernatant was taken, and the absorbance at 498 nm was measured using an ultraviolet-visible spectrophotometer to calculate the concentration of Congo red in the mixed solution. Figure 1 .

[0058] It can be seen from Figure 1 that the photocatalyst Bi7Ta3O 18 / g-C3N4 can catalyze the degradation of Congo red; the photocatalyst Bi7Ta3O 18 / g-C3N4 has different amounts of Bi7Ta3O 18 added, which will cause differences in the effect of photocatalytic degradation of Congo red.

[0059] The photocatalyst 10wt%Bi7Ta3O 18 / g-C3N4 prepared in Example 2 was used to analyze the effect of sodium anthraquinone-2-sulfonate in promoting the photocatalyst to degrade azo dyes.

[0060] Application Example 1

[0061] 100 mg of the photocatalyst 10wt%Bi7Ta3O 18 / g-C3N4 was added to 250 mL of a Congo red solution with a concentration of 50 mg / L, and 1.94 mg of sodium anthraquinone-2-sulfonate was added to obtain a mixed solution.

[0062] The mixed solution was placed under a halogen lamp light source of 220V, 300W for irradiation for 84h, 8mL of the mixed solution was removed every 12h and placed in a centrifuge for centrifugation at a speed of 1000rpm for 100min, the supernatant was taken, and the absorbance at 498nm was measured by a UV-visible spectrophotometer to calculate the concentration of the methyl orange in the mixed solution.

[0063] Application Example 2

[0064] Compared with Application Example 1, the amount of sodium anthraquinone-2-sulfonate added was 3.87mg, and the other conditions were the same as in Application Example 1.

[0065] Application Example 3

[0066] Compared with Application Example 1, the amount of sodium anthraquinone-2-sulfonate added was 7.75mg, and the other conditions were the same as in Application Example 1.

[0067] Application Example 4

[0068] 300mg of the photocatalyst 10wt% Bi7Ta3O 18 / g-C3N4 was added to 280mL of a methyl orange solution with a concentration of 80mg / L, and 5mg of sodium anthraquinone-2-sulfonate was further added to obtain a mixed solution.

[0069] The mixed solution was placed under a halogen lamp light source of 220V, 300W for irradiation for 84h, 8mL of the mixed solution was removed every 12h and placed in a centrifuge for centrifugation at a speed of 1000rpm for 100min, the supernatant was taken, and the absorbance at 498nm was measured by a UV-visible spectrophotometer to calculate the concentration of the methyl orange in the mixed solution.

[0070] Application Example 5

[0071] 400mg of the photocatalyst 10wt% Bi7Ta3O 18 / g-C3N4 was added to 220mL of a Sudan red solution with a concentration of 30mg / L, and 6mg of sodium anthraquinone-2-sulfonate was further added to obtain a mixed solution.

[0072] The mixed solution was placed under a halogen lamp light source of 220V, 300W for irradiation for 84h, 8mL of the mixed solution was removed every 12h and placed in a centrifuge for centrifugation at a speed of 1000rpm for 100min, the supernatant was taken, and the absorbance at 498nm was measured by a UV-visible spectrophotometer to calculate the concentration of the methyl orange in the mixed solution.

[0073] Application Comparative Example

[0074] Compared with Application Example 1, no sodium anthraquinone-2-sulfonate was added, and the other conditions were the same as in Application Example 1.

[0075] The results of the measurements using Examples 1-3 and Comparative Example 1 are shown below. Figure 2 .

[0076] Depend on Figure 2 It can be seen that the degradation rates of Congo red in Application Examples 1-3 with the addition of sodium anthraquinone-2-sulfonate after 84 hours of photocatalysis were 88.4%, 93.22%, and 95.54%, respectively; while the degradation rate of Congo red in the control example without the addition of sodium anthraquinone-2-sulfonate after 84 hours of photocatalysis was only 85.87%. Sodium anthraquinone-2-sulfonate can promote the degradation of the photocatalyst Bi7Ta3O 18 / g-C3N4 degrades azo dyes.

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing a photocatalyst, characterized by, The preparation method comprises the following steps: 1) Bi(NO3)3-5H2O, TaCl5 and ethylene glycol were mixed and reacted to obtain Bi7Ta3O 18 ; The bimelamine is calcined to obtain g-C3N4; The reaction temperature is 180-220 ℃, the reaction time is 20-28 h, and the reaction pH value is 10-11; the calcination temperature is 500-600 ℃, and the calcination time is 3-5 h; In step 1), the mass-volume ratio of Bi(NO3)3·5H2O, TaCl5 and ethylene glycol is 3-3.5 mg: 0.8-1.2 mg: 10-12 mL; 2) Bi7Ta3O 18 and g-C3N4 after calcination to obtain photocatalyst Bi7Ta3O 18 / g-C3N4; In step 2), the calcination temperature is 350-450 ℃, and the calcination time is 0.5-1.5 h; Step 2) the photocatalyst Bi7Ta3O 18 Bi7Ta3O 18 5-80%.

2. The photocatalyst prepared by the preparation method of claim 1.

3. Application of sodium anthraquinone-2-sulfonate in promoting degradation of azo dyes by the photocatalyst of claim 2.

4. Use according to claim 3, characterized in that, The azo dyes comprise one or more of reactive red, methyl orange, congo red, acid orange and sudan red, and the concentration of the azo dyes is 20-100 mg / L.

5. Use according to claim 3 or 4, characterized in that, The mass-volume ratio of the photocatalyst, sodium anthraquinone-2-sulfonate and azo dyes is 80-480 mg: 1.5-9.3 mg: 200-300 mL.

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