阅读说明：本技术 复合膜光催化剂及其制备方法和用途 (Composite membrane photocatalyst and preparation method and application thereof ) 是由 赵娣 卢艳红 陈钰 任萍 李爱昌 于 2020-06-28 设计创作，主要内容包括：本发明公开了一种复合膜光催化剂及其制备方法和用途。该复合膜光催化剂的制备方法包括：将银离子源、碱金属氯化物和配位剂形成电解液,调节电解液的pH至8～13形成镀液,以镍作为阴极,进行恒电流电沉积形成Ag/Ni薄膜；将溴离子源、磷酸铵和氧化石墨烯形成悬浊液,将悬浊液在5～18℃的条件下超声形成电解悬浮液；以Ag/Ni薄膜作为阳极,电解悬浮液作为镀液,进行恒电流复合电沉积形成Ag/AgBr/GO/Ni薄膜；其中,电解悬浮液中氧化石墨烯的浓度为0.18～0.28g·L<Sup>-1</Sup>,电解悬浮液的温度为10～20℃；恒电流复合电沉积的电流密度为2～2.6mA·cm<Sup>-2</Sup>,沉积时间为16～20min；将Ag/AgBr/GO/Ni薄膜在100～180℃的条件下进行保温处理,得到Ag/AgBr/GO/Ni复合薄膜光催化剂。该光催化剂对罗丹明B具有良好的降解作用。(The invention discloses a composite membrane photocatalyst and a preparation method and application thereof. The preparation method of the composite membrane photocatalyst comprises the following steps: forming an electrolyte from a silver ion source, an alkali metal chloride and a coordination agent, adjusting the pH value of the electrolyte to 8-13 to form a plating solution, and performing constant current electrodeposition by taking nickel as a cathode to form an Ag/Ni film; forming a suspension from a bromide ion source, ammonium phosphate and graphene oxide, and ultrasonically treating the suspension at 5-18 ℃ to form an electrolytic suspension; taking the Ag/Ni film as an anode and the electrolytic suspension as plating solution, and carrying out constant-current composite electrodeposition to form an Ag/AgBr/GO/Ni film; wherein the content of the first and second substances,the concentration of the graphene oxide in the electrolytic suspension is 0.18-0.28 g.L ‑1 The temperature of the electrolytic suspension is 10-20 ℃; the current density of the constant-current composite electrodeposition is 2-2.6 mA-cm ‑2 The deposition time is 16-20 min; and carrying out heat preservation treatment on the Ag/AgBr/GO/Ni film at the temperature of 100-180 ℃ to obtain the Ag/AgBr/GO/Ni composite film photocatalyst. The photocatalyst has a good degradation effect on rhodamine B.)

1. A preparation method of a composite membrane photocatalyst is characterized by comprising the following steps:

(1) forming an electrolyte from a silver ion source, an alkali metal chloride and a coordination agent, adjusting the pH value of the electrolyte to 8-13 to form a plating solution, and performing constant current electrodeposition by taking nickel as a cathode to form an Ag/Ni film;

(2) forming a suspension from a bromide ion source, ammonium phosphate and graphene oxide, and ultrasonically treating the suspension at 5-18 ℃ to form an electrolytic suspension; taking the Ag/Ni film as an anode and the electrolytic suspension as plating solution, and carrying out constant-current composite electrodeposition to form an Ag/AgBr/GO/Ni film; wherein the concentration of the graphene oxide in the electrolytic suspension is 0.18-0.28 g.L^-1The temperature of the electrolytic suspension is 10-20 ℃; the current density of the constant-current composite electrodeposition is 2-2.6 mA-cm^-2The deposition time is 16-20 min;

(3) and carrying out heat preservation treatment on the Ag/AgBr/GO/Ni film at the temperature of 100-180 ℃ to obtain the Ag/AgBr/GO/Ni composite film photocatalyst.

2. The method of claim 1, wherein the complexing agent is selected from one of succinimide, hydantoin, alkyl-substituted succinimide, and alkyl-substituted hydantoin, and the anode is selected from one of stainless steel and graphite.

3. The production method according to claim 1, wherein the silver ion source is at least one selected from the group consisting of silver nitrate and silver sulfate; the alkali metal chloride is at least one selected from potassium chloride and sodium chloride; the pH of the electrolyte is adjusted using a mixture of alkali metal hydroxide and inorganic acid.

4. The method according to claim 1, wherein the constant current electrodeposition in the step (1) has a current density of 1 to 3 mA-cm^-2The deposition time is 20-40 min.

5. The method according to claim 1, wherein the silver ion source is silver nitrate, the alkali metal chloride is potassium chloride, and the complexing agent is hydantoin; the concentration of silver nitrate in the electrolyte is 12-25 g/L, the concentration of potassium chloride is 5-15 g/L, and the concentration of hydantoin is 25-55 g/L.

6. The method according to claim 1, wherein the bromide ion source is at least one selected from the group consisting of sodium bromide and potassium bromide; the molar ratio of the bromine ions to the ammonium phosphate is (1-6): 10.

7. The preparation method according to claim 1, wherein the cathode in the step (2) is selected from one of stainless steel and graphite; the concentration of bromide ions in the electrolytic suspension is 0.1-0.6 mol/L, the concentration of ammonium phosphate is 0.5-1.5 mol/L, and the pH value of the electrolytic suspension is 7-10.

8. The method according to any one of claims 1 to 7, wherein the heat-retaining treatment is carried out for 0.5 to 2 hours.

9. A composite membrane photocatalyst prepared by the preparation method of any one of claims 1 to 8.

10. Use of the composite membrane photocatalyst according to claim 9 in the treatment of organic dyes in wastewater.

Technical Field

The invention relates to a composite membrane photocatalyst and a preparation method and application thereof, in particular to an Ag/AgBr/GO/Ni composite membrane photocatalyst and a preparation method and application thereof.

Background

The photocatalytic oxidation can directly utilize sunlight to catalytically degrade organic pollutants which are difficult to degrade in water or air and have low content, and has obvious advantages and wide application prospect in environmental purification, particularly in sewage treatment. The Ag/AgBr surface plasma photocatalyst shows strong absorption to visible light due to obvious surface plasma resonance, and has strong photocatalytic activity. Graphene Oxide (GO) is used as a pi system material, and because various oxygen-containing groups exist on the framework of the graphene oxide, a rich practical space is provided for constructing a composite functional material. The graphene oxide has good chemical stability, excellent conductivity and an ultra-large specific surface area, and not only can enhance the light absorption performance of the catalyst, but also can rapidly transfer photo-generated electrons and enhance the catalytic activity.

CN108525683A discloses a preparation method of a three-dimensional graphene aerogel/silver bromide/silver photocatalyst. Ag and AgBr nano particles grow on the graphene hydrogel in situ by utilizing the reducibility of the graphene hydrogel and the amphipathy of CTAB, and the three-dimensional GA/AgBr/Ag photocatalyst is prepared by freeze drying. The photocatalyst obtained by the method is in a powder form, is not beneficial to rapid separation and recycling when used for treating polluted water, and has poor controllability on the microstructure of the photocatalyst.

Zhao Weng et al famous' visible light high catalytic activity GO/Ag₃PO₄Preparation and Properties of/Ni composite films "(inorganic chemistry report, vol. 36, 2 nd, 2 months 2020) GO/Ag₃PO₄Of a/Ni composite filmA preparation method. Preparing the Ag/Ni film by an electrochemical method. And (3) adding graphene oxide aqueous suspension into ammonium phosphate solution with the pH of 8 by taking the Ag/Ni film as an anode and the stainless steel sheet as a cathode at room temperature, and preparing the electrolytic suspension after ultrasonic oscillation. Controlling the current density to be 2.5mA cm^-2The electrodeposition time was 30 s. The post-treatment condition is heat preservation for 1h at 70 ℃. The GO/Ag₃PO₄The degradation performance of the/Ni composite film on rhodamine B is poor.

The preparation and performance of the thin film surface plasma photocatalyst Ag @ AgBr/CNT/Ni (journal of inorganic chemistry, volume 34, No. 11, 11 months of 2018) of Liericang et al discloses a preparation method of Ag @ AgBr/CNT/Ni. Preparing the Ag/Ni film by an electrochemical method. An Ag/Ni film is used as an anode at room temperature, and a stainless steel sheet is used as a cathode. Preparing mixed aqueous solution with the concentration of sodium bromide and ammonium phosphate being 0.3mol/L and 1.0mol/L respectively, adding CNT in the mixed solution, and forming electrolytic suspension through ultrasonic oscillation. And carrying out constant-current composite electrodeposition at room temperature under natural light. The distance between the electrodes was 3cm, the pH of the electrolytic suspension was 8, the concentration of CNT was 1.25g/L, and the anode current density was 3 mA. cm^-2The deposition time was 18 min. The post-treatment condition is heat preservation at 140 ℃ for 1 h. The dispersibility of the carbon nano tube in water is poor, the formed electrolytic suspension is not uniformly dispersed, the deposition uniformity of the carbon nano tube on the Ag/Ni film is poor, and the degradation performance of the carbon nano tube on rhodamine B is poor.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a method for preparing a composite membrane photocatalyst, and the composite membrane photocatalyst obtained by the method has a good catalytic degradation effect on rhodamine B. Another object of the present invention is to provide a composite membrane photocatalyst. The invention further aims to provide application of the composite membrane photocatalyst in treating organic dye in wastewater.

In one aspect, the present invention provides a method for preparing a composite membrane photocatalyst, comprising the steps of:

(1) forming an electrolyte from a silver ion source, an alkali metal chloride and a coordination agent, adjusting the pH value of the electrolyte to 8-13 to form a plating solution, and performing constant current electrodeposition by taking nickel as a cathode to form an Ag/Ni film;

(2) forming a suspension from a bromide ion source, ammonium phosphate and graphene oxide, and ultrasonically treating the suspension at 5-18 ℃ to form an electrolytic suspension; taking the Ag/Ni film as an anode and the electrolytic suspension as plating solution, and carrying out constant-current composite electrodeposition to form an Ag/AgBr/GO/Ni film; wherein the concentration of the graphene oxide in the electrolytic suspension is 0.18-0.28 g.L^-1The temperature of the electrolytic suspension is 10-20 ℃; the current density of the constant-current composite electrodeposition is 2-2.6 mA-cm^-2The deposition time is 16-20 min;

(3) and carrying out heat preservation treatment on the Ag/AgBr/GO/Ni film at the temperature of 100-180 ℃ to obtain the Ag/AgBr/GO/Ni composite film photocatalyst.

According to the preparation method of the present invention, preferably, the complexing agent is selected from one of succinimide, hydantoin, alkyl-substituted succinimide, or alkyl-substituted hydantoin, and the anode is selected from one of stainless steel and graphite.

According to the production method of the present invention, preferably, the silver ion source is selected from at least one of silver nitrate and silver sulfate; the alkali metal chloride is at least one selected from potassium chloride and sodium chloride; the pH of the electrolyte is adjusted using a mixture of alkali metal hydroxide and inorganic acid.

According to the preparation method of the invention, preferably, the constant current electrodeposition in the step (1) has the current density of 1-3 mA-cm^-2The deposition time is 20-40 min.

According to the preparation method of the present invention, preferably, the silver ion source is silver nitrate, the alkali metal chloride is potassium chloride, and the complexing agent is hydantoin; the concentration of silver nitrate in the electrolyte is 12-25 g/L, the concentration of potassium chloride is 5-15 g/L, and the concentration of hydantoin is 25-55 g/L.

According to the preparation method of the present invention, preferably, the bromide ion source is selected from at least one of sodium bromide and potassium bromide; the molar ratio of the bromine ions to the ammonium phosphate is (1-6): 10.

According to the preparation method of the present invention, preferably, the cathode in the step (2) is selected from one of stainless steel and graphite; the concentration of bromide ions in the electrolytic suspension is 0.1-0.6 mol/L, the concentration of ammonium phosphate is 0.5-1.5 mol/L, and the pH value of the electrolytic suspension is 7-10.

According to the preparation method provided by the invention, the time of the heat preservation treatment is preferably 0.5-2 h.

In another aspect, the invention provides a composite membrane photocatalyst prepared by the above preparation method.

In another aspect, the invention provides an application of a composite membrane photocatalyst in treating organic dyes in wastewater.

According to the invention, bromide ions and graphene oxide are deposited on the Ag/Ni film by adopting a constant-current composite electrodeposition method to form the Ag/AgBr/GO/Ni composite film photocatalyst, and various parameters in the preparation process are controlled, so that the Ag/AgBr/GO/Ni composite film photocatalyst has a good photocatalytic decomposition effect on rhodamine B.

Drawings

FIG. 1 is a scanning electron microscope image of Ag/AgBr/Ni thin film photocatalyst prepared in comparative example 9 of the present invention.

FIG. 2 is a scanning electron microscope image of the Ag/AgBr/GO/Ni composite membrane photocatalyst prepared in example 1 of the present invention.

Fig. 3 is a diagram showing the photocatalytic activity of the catalyst films prepared in example 1 and comparative example 9 of the present invention against rhodamine B.

Fig. 4 is a graph showing the photocatalytic activity of the catalyst films prepared in example 1 of the present invention and comparative example 9 against congo red.

FIG. 5 is a diagram showing the photocatalytic activity of the catalyst films prepared in example 1, comparative examples 2 to 4 and comparative example 9 of the present invention against rhodamine B. (example 1: 0.2g/L GO; comparative example 2: 0.04g/L GO; comparative example 3: 0.1g/L GO; comparative example 4: 0.3g/L GO; comparative example 9: 0g/L GO)

Detailed Description

The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.

The preparation method of the composite membrane photocatalyst comprises the following steps: (1) preparing an Ag/Ni film; (2) preparing an Ag/AgBr/GO/Ni film; (3) and (5) post-processing. As described in detail below.

< preparation of Ag/Ni film >

Forming an electrolyte from a silver ion source, an alkali metal chloride and a complexing agent, adjusting the pH value of the electrolyte to 8-13 to form a plating solution, and performing constant current electrodeposition by taking nickel as a cathode to form an Ag/Ni film.

The source of silver ions in the present invention may be an inorganic salt of silver, such as silver nitrate, silver sulfate, and the like. According to one embodiment of the invention, the source of silver ions is silver nitrate. The concentration of silver nitrate in the electrolyte can be 12-25 g/L; preferably 14-20 g/L; more preferably 15 to 18 g/L.

The alkali metal chloride of the present invention may be selected from at least one of potassium chloride or sodium chloride. According to one embodiment of the invention, the alkali metal chloride is potassium chloride. The concentration of potassium chloride in the electrolyte can be 5-15 g/L; preferably 7-13 g/L; more preferably 7 to 11 g/L.

The complexing agent of the invention can be selected from one of succinimide, hydantoin, alkyl-substituted succinimide or alkyl-substituted hydantoin; preferably, the complexing agent is selected from one of succinimide, hydantoin and 5-methylhydantoin; more preferably, the complexing agent is hydantoin. The concentration of the hydantoin in the electrolyte can be 25-55 g/L; preferably 30-50 g/L; more preferably 35 to 45 g/L. This contributes to the improvement in the quality of the Ag/Ni film.

The pH value of the electrolyte can be 8-13; preferably 9-12; more preferably 10 to 11. This helps to obtain Ag/Ni films of stable quality.

The pH of the electrolyte may be adjusted by a mixture of an alkali metal hydroxide and a mineral acid. Examples of alkali metal hydroxides include, but are not limited to, sodium hydroxide, potassium hydroxide. Examples of inorganic acids include, but are not limited to, nitric acid, sulfuric acid, hydrochloric acid. According to one embodiment of the invention, the pH of the electrolyte may be adjusted by a mixture of potassium hydroxide and nitric acid.

The anode may be an inert electrode such as stainless steel, graphite, and the like. Preferably, the anode is stainless steel. According to one embodiment of the present invention, the anode is a stainless steel plate of (1 to 6cm) × (2 to 7 cm).

The cathode is nickel. According to one embodiment of the present invention, the cathode is a nickel plate (0.2 to 3cm) × (0.5 to 5 cm). The distance between the cathode and the anode can be 0.5-7 cm; preferably 1-5 cm; more preferably 2 to 4 cm.

The current density of the constant current electrodeposition can be 1-3 mA-cm^-2(ii) a Preferably 1.5 to 2.5mA cm^-2(ii) a More preferably 1.8 to 2.2mA cm^-2. Such conditions are helpful to control the microstructure of the Ag/Ni film and obtain an Ag/Ni film suitable for preparing composite film photocatalysts.

The deposition time of the constant current electrodeposition can be 20-40 min; preferably 25-35 min; more preferably 22 to 33 min. Such conditions are helpful to control the microstructure of the Ag/Ni film and obtain an Ag/Ni film suitable for preparing composite film photocatalysts.

< preparation of Ag/AgBr/GO/Ni film >

Forming a suspension from a bromide ion source, ammonium phosphate and graphene oxide, and ultrasonically treating the suspension at 5-18 ℃ to form an electrolytic suspension; taking the Ag/Ni film as an anode and the electrolytic suspension as plating solution, and carrying out constant-current composite electrodeposition to form an Ag/AgBr/GO/Ni film; wherein the concentration of the graphene oxide in the electrolytic suspension is 0.18-0.28 g.L^-1The temperature of the electrolytic suspension is 10-20 ℃; the current density of the constant-current composite electrodeposition is 2-2.6 mA-cm^-2The deposition time is 16-20 min.

The bromide ion source in the present invention may be an alkali metal bromide such as sodium bromide, potassium bromide, etc. According to one embodiment of the invention, the source of bromide ions is sodium bromide. The concentration of bromide ions in the electrolytic suspension can be 0.1-0.6 mol/L, preferably 0.1-0.4 mol/L; more preferably 0.2 to 0.4 mol/L.

The molar ratio of the bromine ions to the ammonium phosphate can be (1-6) to 10; preferably (1-4) 10; more preferably (2-4): 10. This helps to improve the catalytic activity of the composite membrane photocatalyst.

The concentration of ammonium phosphate in the electrolytic suspension can be 0.5-1.5 mol/L, preferably 0.7-1.3 mol/L; more preferably 0.8 to 1.2 mol/L.

According to the invention, the carbon nanotubes are replaced by graphene oxide, so that the agglomeration of the carbon nanotubes is avoided, and the catalytic activity of the composite membrane photocatalyst is higher. The concentration of the graphene oxide in the electrolytic suspension is 0.18-0.28 g.L^-1(ii) a Preferably 0.18 to 0.25 g.L^-1(ii) a More preferably 0.18 to 0.22 g.L^-1. This helps to improve the catalytic activity of the composite membrane photocatalyst.

The pH value of the electrolytic suspension can be 7-10; preferably 7-9; more preferably 7.5 to 8.5.

Sonication can be carried out in an ice-water bath. The ultrasonic temperature is 5-18 ℃; preferably 5-15 ℃; more preferably 8 to 12 ℃. This helps to improve the catalytic activity of the composite membrane photocatalyst. The present inventors have found that ultrasound temperature has a significant effect on the composite membrane. The ultrasonic temperature is lower than 5 ℃, which is not beneficial to the formation of the composite membrane; the ultrasonic temperature is higher than 18 ℃, and the catalytic activity of the composite membrane is deteriorated.

The temperature of the electrolytic suspension is 10-20 ℃; preferably 15-20 ℃; more preferably 17 to 20 ℃. This helps to improve the catalytic activity of the composite membrane photocatalyst. The invention finds that the temperature of the electrolytic suspension has an important influence on the composite membrane. The temperature of the electrolytic suspension is lower than 10 ℃, which is not beneficial to the formation of the composite membrane; the temperature of the electrolytic suspension is higher than 20 ℃, and the catalytic activity of the composite membrane is deteriorated.

The cathode may be an inert electrode such as stainless steel, graphite, and the like. Preferably, the cathode is stainless steel. According to one embodiment of the invention, the cathode is a stainless steel plate. The distance between the cathode and the anode can be 0.5-7 cm; preferably 1-5 cm; more preferably 2 to 4 cm.

The current density of the constant-current composite electrodeposition can be 2-2.6 mA-cm^-2(ii) a Preferably 2.2 to 2.6mA cm^-2(ii) a More preferably 2.3 to 2.6mA cm^-2. Such conditions are helpful for controlling the microstructure of the composite film photocatalyst and improving the catalytic activity.

The deposition time of the constant current composite electrodeposition can be 16-20 min; preferably 17-20 min; more preferably 17-19 min. Such conditions are helpful for controlling the microstructure of the composite film photocatalyst and improving the catalytic activity.

< step of post-treatment >

And carrying out heat preservation treatment on the Ag/AgBr/GO/Ni film at the temperature of 100-180 ℃ to obtain the Ag/AgBr/GO/Ni composite film photocatalyst.

In the invention, the temperature of the heat preservation treatment can be 100-180 ℃; preferably 120-160 ℃; more preferably 130 to 150 ℃. The time of heat preservation treatment can be 0.5-2 h; preferably 0.7-1.5 h; more preferably 0.8 to 1.2 hours. Thus being beneficial to improving the catalytic activity of the Ag/AgBr/GO/Ni composite film photocatalyst.

The Ag/AgBr/GO/Ni composite film photocatalyst is prepared by the method, and the degradation rate of rhodamine B in 15min can reach more than 98%.

The Ag/AgBr/GO/Ni composite film photocatalyst has good catalytic activity on organic dye, so that the photocatalyst can be used for treating the organic dye in wastewater, and preferably rhodamine B.