All-weather interface evaporator capable of preventing volatile organic compounds from escaping and concentrated water from being generated and application of all-weather interface evaporator

Abstract

The invention discloses an all-weather interface evaporator capable of preventing volatile organic compounds from escaping and concentrated water from being generated and application of the all-weather interface evaporator, and belongs to the technical field of wastewater treatment. The interface evaporator comprises an evaporation layer loaded with a catalyst, a water conveying medium and inert metal, the evaporation layer loaded with the catalyst serves as a cathode, and the inert metal serves as an anode; the anode is located below the water conveying medium, and the water conveying medium makes contact with the evaporation layer loaded with the catalyst and the inert metal. According to the invention, photo-thermal and electric heating are combined, a catalyst is loaded on the evaporation layer, wastewater is conveyed to the evaporation layer through a water conveying medium, the electrified evaporation layer generates free radicals through an electro-Fenton reaction, and volatile and non-volatile organic compounds in the wastewater are degraded, so that organic compounds in condensate and a base solution can be greatly reduced; the defects that volatile organic compounds escape and organic compounds are enriched in a base solution in a traditional solar interface evaporation technology are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and more particularly to an all-weather interface evaporator capable of preventing the escape of volatile organic matter and the generation of concentrated water, and an application thereof. Background Art

[0002] Due to limited global freshwater resources and severe water pollution, freshwater shortages have been a global crisis, significantly impacting the sustainable development of society and posing a serious threat to the natural environment and human health. Producing clean water through sustainable and environmentally friendly strategies is an important and viable approach. Among various water treatment methods, solar-driven interfacial evaporation is considered a freshwater production technology with the advantages of renewable energy input, high energy efficiency, and a low carbon footprint. It has universal applicability in both seawater desalination and drinking water purification.

[0003] Currently, in traditional solar-driven interfacial evaporation processes, steam generation can be accelerated by localized heating at the air / water interface using photothermal materials. However, most solar-driven interfacial evaporation processes are unable to purify water containing volatile organic compounds (VOCs), resulting in the presence or even enrichment of VOCs with low saturated vapor pressures in the condensed water. Furthermore, the non-volatile organic compounds concentrated in the water require time-consuming and labor-intensive secondary treatment to prevent their direct release into the ecological environment.

[0004] In summary, there is an urgent need to develop a treatment method for the problems of volatile organic pollutants escaping and organic pollutants concentration in the bottom liquid during wastewater treatment. Summary of the Invention

[0005] The present invention addresses the defects of the above-mentioned traditional solar-driven interfacial evaporation process and provides an all-weather interfacial evaporator, a preparation method, and an application thereof, which can prevent the escape of volatile organic compounds and the production of concentrated water. The present invention combines photothermal and electric heating, loads a catalyst on the evaporation layer, and transmits wastewater to the evaporation layer via a water transmission medium. After energization, the evaporation layer produces free radicals through the electro-Fenton reaction, which degrades volatile and non-volatile organic compounds in the wastewater. This can significantly reduce the organic matter in both the condensate and the bottom liquid, making up for the defects of traditional solar interfacial evaporation technology in terms of the escape of volatile organic compounds and the enrichment of organic matter in the bottom liquid.

[0006] The present invention provides an all-weather interface evaporator capable of preventing the escape of volatile organic compounds and the generation of concentrated water. The all-weather interface evaporator comprises a catalyst-loaded evaporation layer, a water transport medium, and a catalyst-loaded evaporation layer. The catalyst-loaded evaporation layer is placed above the water transport medium, and the catalyst-loaded evaporation layer is placed below the water transport medium, and the water transport medium is in contact with the catalyst-loaded evaporation layer and the catalyst-loaded evaporation layer, respectively. A method for preparing the catalyst-loaded evaporation layer comprises the following steps: (1) The carbon nanotubes are uniformly dispersed in a mixed acid solution of nitric acid and sulfuric acid, stirred continuously at 75-85 °C for 2-4 h, allowed to stand for 1-2 h, and then washed with ultrapure water and filtered; subsequently, the precipitate is freeze-dried to obtain oxidized carbon nanotubes; (2) uniformly dispersing oxidized carbon nanotubes and ferric chloride hexahydrate (FeCl3·6H2O) in anhydrous ethanol or isopropanol to obtain a mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate; wherein the mass ratio of ferric chloride hexahydrate to oxidized carbon nanotubes is 0.5 to 2:1, and most preferably 1:1; (3) pouring a mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate into a spray gun and spraying it on the surface (one side) of the carbon cloth substrate, and drying it to obtain ferric chloride hexahydrate / oxidized carbon nanotubes / carbon cloth; (4) Arranging ferric chloride hexahydrate / carbon oxide nanotubes / carbon in a crucible, sealing it, and calcining it at 200-220°C for 1.5-2 hours to obtain an evaporation layer of the supported catalyst; (5) Coating the surface of the calcined evaporation layer with a mixed solution of Nafion solution and water, and drying the mixture to obtain a catalyst-loaded evaporation layer; wherein the volume ratio of Nafion solution to water in the mixed solution of Nafion solution and water is 30-35:100.

[0007] Furthermore, the water transport medium is one or more of dust-free paper and cotton cloth.

[0008] Furthermore, the inert metal is an inert metal electrode such as ruthenium, iridium, titanium, or platinum.

[0009] Furthermore, in step (1), the volume ratio of nitric acid to sulfuric acid in the mixed acid solution of nitric acid and sulfuric acid is 30-35:100; wherein the concentration of nitric acid is 15-17 mol / L, and the concentration of sulfuric acid is 17-19 mol / L.

[0010] Furthermore, in step (1), the concentration of the carbon nanotubes in the mixed acid solution of nitric acid and sulfuric acid is 20 to 30 g / L.

[0011] Furthermore, in step (2), the concentrations of oxidized carbon nanotubes and ferric chloride hexahydrate in the mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate are 6-8 g / L and 3-12 g / L (preferably 6-7 g / L), respectively.

[0012] Furthermore, in step (2), the carbon cloth substrate is first rinsed with ethanol, then rinsed with deionized water, and dried to obtain a carbon cloth substrate.

[0013] Furthermore, the drying conditions are: temperature of 40-60° C., and drying time of 15-30 min.

[0014] Furthermore, in step (2), the preparation method of the mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate is as follows: adding oxidized carbon nanotubes and ferric chloride hexahydrate to anhydrous ethanol or isopropanol, and ultrasonically treating for 3 to 4 hours to uniformly disperse the oxidized carbon nanotubes and ferric chloride hexahydrate in the anhydrous ethanol or isopropanol to obtain a mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate.

[0015] Furthermore, in step (3), the mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate is heated at 0.3-0.4 ml / cm 2 The standard is evenly sprayed on the surface of the carbon cloth substrate.

[0016] Furthermore, in step (4), the crucible is sealed using polytetrafluoroethylene tape.

[0017] Furthermore, in step (5), the mass fraction of the Nafion solution is 4-6 wt%.

[0018] Furthermore, in step (5), the surface of the calcined evaporation layer is heated to 0.1-0.15 ml / cm 2 A mixed solution of standard coating Nafion solution and water.

[0019] The present invention also provides a method for preparing the all-weather interface evaporator, comprising the following steps: The catalyst-loaded evaporation layer is placed parallel to the water transport medium, and the water transport medium is placed parallel to the middle of the catalyst-loaded evaporation layer and the anode. The water transport medium is in contact with the catalyst-loaded evaporation layer and the inert metal respectively. The water transport medium is in contact with the electrothermal interface generated by the energized catalyst-loaded evaporation layer. After light is applied, the catalyst-loaded evaporation layer acts as a working electrode and simultaneously generates a photothermal interface, thereby obtaining an all-weather interface evaporator.

[0020] The present invention provides the use of the above-mentioned all-weather interface evaporator or the all-weather interface evaporator prepared by the above-mentioned preparation method in the treatment of wastewater containing volatile organic compounds. The application method comprises the following steps: In a three-electrode system, the catalyst-loaded evaporation layer is connected to the working electrode of the electrochemical workstation as a cathode, and the inert metal (ruthenium, iridium, titanium or platinum sheet) is connected to the counter electrode as an anode; one end of the water transport medium is immersed in the organic wastewater, and the other end is placed in a container for collecting purified concentrated water. The evaporation layer is illuminated by sunlight to treat the organic wastewater (containing volatile organic wastewater and / or non-volatile organic pollutants), degrade the volatile organic pollutants that evaporate and degrade the non-volatile organic pollutants concentrated in the bottom liquid.

[0021] Furthermore, it also includes a reference electrode, which is Ag / AgCl and is located between the catalyst-loaded evaporation layer and the water transport medium.

[0022] Furthermore, the applied voltage is -0.4V~-1.0V; the pH of the wastewater is 3~9, preferably 3~4; the light intensity is 1kW·m -2 ~1.1 kW·m -2 The pollutants in the organic wastewater are one or more of phenol, sulfamethoxazole, N,N-dimethylformamide, atrazine, dyes, and antibiotics. The volatile organic pollutants that escape are phenol and N,N-dimethylformamide, and the non-volatile organic pollutants that concentrate in the bottom liquid are one or more of sulfamethoxazole, atrazine, dyes, and antibiotics.

[0023] Furthermore, the organic wastewater must also contain anhydrous sodium sulfate, wherein the concentration of sodium sulfate is 0.04 to 0.05 mol / L.

[0024] In this invention, a catalyst-loaded evaporation layer serves as a photothermal interface. When the evaporation layer is energized, localized Joule heating is generated. A water transport medium spontaneously transports organic wastewater to the photothermal / electrothermal interface via a siphon mechanism. The energized evaporation layer then degrades organic matter in the water through the strong oxidizing free radicals generated by the electro-Fenton reaction. This combination of photoelectricity and light improves evaporation efficiency and overcomes the weather constraints of solar interface evaporation. The water transport medium can transport organic matter enriched in the bottom liquid to the interface where the strong oxidizing free radicals are generated. Furthermore, the evaporator layer's synthesis method is simple, exhibits low metal leaching rates, and exhibits excellent repeatability. Furthermore, it can utilize solar power generation, contributing to global sustainable development and possessing broad application prospects in water treatment.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The evaporation layer prepared in the present invention can generate Joule heat after power is applied, which can increase the evaporation rate.

[0026] (2) The evaporator prepared by the present invention has a good catalytic degradation effect on volatile organic compounds released during the evaporation process by coupling the electro-Fenton technology and solar-driven interface evaporation. Compared with other traditional solar interface evaporation technologies, it makes up for the defect of being unable to solve the problem of volatile organic compounds releasing.

[0027] (3) The evaporator prepared in the present invention can spontaneously transport the bottom liquid to the photothermal / electrothermal interface through the siphon mode water medium. After the energization, the evaporation layer degrades the organic matter in the bottom liquid through the strong oxidizing free radicals generated by the electro-Fenton reaction, which makes up for the defect of being unable to solve the concentration of organic matter in the bottom liquid.

[0028] (4) The evaporator prepared in the present invention can also drive interface evaporation through electrothermal drive in the absence of solar energy, successfully breaking through the strong dependence of solar interface evaporation technology on weather factors and realizing all-weather evaporation.

[0029] (5) The preparation process of the present invention is simple, has good repeatability, high economic benefits, does not generate additional pollution, and can be promoted and applied on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described with reference to the accompanying drawings and embodiments.

[0031] Figure 1 This is a scanning electron microscope image of the prepared evaporated layer.

[0032] Figure 2 Schematic diagram of the structure of the prepared interface evaporator.

[0033] Figure 3 This is a diagram showing the degradation effect of organic matter in the condensate and bottom liquid by the prepared interfacial evaporator under different pH conditions.

[0034] Figure 4 This is the effect diagram of the prepared interfacial evaporator circulating to treat organic wastewater.

[0035] Figure 5 This is a diagram showing the degradation effect of the prepared interfacial evaporator on different organic pollutants. DETAILED DESCRIPTION

[0036] The embodiments described below are merely typical embodiments of the present invention and do not constitute an improper limitation of the present invention. Therefore, all obvious modifications described within the scope of the present invention and other modifications that do not depart from the essence of the present invention should be included in the scope of protection of the present invention.

[0037] The following technical solutions are combined to further illustrate the specific embodiments of the present invention, but the present invention is not limited to the following examples. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0038] Example 1 A method for preparing a catalyst-loaded evaporation layer comprises the following steps: (1) 2 g of carbon nanotubes were dispersed in 100 ml of a mixed acid solution of 16 mol / L nitric acid and 18 mol / L sulfuric acid in a volume ratio of 40:60, stirred at 80 °C for 3 h, allowed to stand for 24 h, and then washed with ultrapure water and filtered. Subsequently, the precipitate was freeze-dried to obtain oxidized carbon nanotubes. (2) 20 mg of FeCl3•6H2O and 20 mg of synthesized oxidized carbon nanotubes were mixed and uniformly dispersed in 3 ml of ethanol and ultrasonicated for 3 h; (3) First, rinse the carbon cloth with ethanol, then rinse with deionized water, and dry it to obtain a carbon cloth substrate; (4) Pour the mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate into the spray gun and spray it evenly onto one side of the carbon cloth (3×3 cm 2 ); then, the composite sample was continuously calcined at 220 °C in a sealed crucible for 1.5 h to obtain an evaporation layer loaded with the catalyst; a mixed solution of 1 ml of Nafion solution (mass fraction of 5 wt%, purchased from Suzhou Shengernuo Enterprise Store) and water in a volume ratio of 35:100 was coated on the surface of the evaporation layer, and then dried to obtain an evaporation layer loaded with the catalyst.

[0039] Figure 1 The SEM image of the evaporated layer prepared by Figure 1 It can be seen that there is a fish-scale morphology on the surface of the evaporation layer, and there is an obvious acidified carbon nanotube structure underneath, which helps to enhance the photothermal conversion performance.

[0040] Example 2 An interfacial evaporator for treating organic wastewater comprises the catalyst-loaded evaporation layer prepared in Example 1, a water-transport medium, and an inert metal. The catalyst-loaded evaporation layer serves as the cathode, and the inert metal serves as the anode. The water-transport medium is placed parallel to the catalyst-loaded evaporation layer and the ruthenium-iridium-titanium anode. The catalyst-loaded evaporation layer is placed above the water-transport medium, and the inert metal is located below the water-transport medium. The water-transport medium contacts the catalyst-loaded evaporation layer and the inert metal, respectively. The water-transport medium is a cotton cloth with a length of 15 cm, a width of 3 cm, and a thickness of 1 mm. The anode is a ruthenium-iridium-titanium electrode with a thickness of 1 mm and an area of ​​3 x 3 cm. 2 .

[0041] The application of the above-mentioned interface evaporator to organic wastewater includes the following steps: In a three-electrode system, the catalyst-loaded evaporation layer prepared in Example 1 was connected to the working electrode of the electrochemical workstation as the cathode, the ruthenium-iridium-titanium counter electrode was connected as the anode, and the Ag / AgCl reference electrode was placed in parallel on the water medium. The applied voltage was set to -0.8 V and the oxygen flow rate was 100 mL min. -1 Degradation of organic pollutants: One end of the water medium was immersed in 20 ml of organic wastewater containing 20 ppm of phenol (solution pH was 3) at a depth of 5 cm, and the other end was placed in a container for collecting purified concentrated water and hung 5 cm below the container. -2) irradiates the catalyst-loaded evaporation layer to treat the wastewater. After purification, the concentrated water volume gradually increases, and the water level continues to rise until it contacts the outlet of the water medium.

[0042] Example 3 The difference between this embodiment and Example 1 is that the pH of the organic wastewater is adjusted to 6 using a 1M sulfuric acid solution.

[0043] Example 4 The difference between this embodiment and Example 1 is that the pH of the organic wastewater is adjusted to 9 with 1M sodium hydroxide solution.

[0044] Figure 3 The following is a comparison chart of the effects of the evaporator on the degradation of organic pollutants in the condensate and bottom liquid in organic wastewater under the conditions of Examples 2, 3, and 4. Figure 2 As can be seen from the evaporator structure shown, the photoelectric combined evaporator of the present invention has the effect of preventing volatile organic compounds from escaping and concentrated water from being produced.

[0045] Example 5 The interfacial evaporator's recycling treatment effect on organic wastewater. After the interfacial evaporator treated the organic wastewater containing 20 ppm of phenol (pH 3) in Example 2, it was replaced with fresh organic wastewater containing 20 ppm of phenol (pH 3) and treated according to the conditions of Example 2. The above operation was repeated five times, and the concentration of organic phenol in the condensate and bottom liquid was measured by high-performance liquid chromatography. The results are shown in Figure 4.

[0046] Figure 4 This is the effect diagram of recycling treatment of organic wastewater. Figure 4 It can be seen that after being recycled 5 times, the evaporation layer prepared in Example 1 still exhibits a highly efficient effect of degrading organic matter, which shows that the interface evaporator of the present invention has good stability.

[0047] Example 6 Catalytic degradation effect on other different organic pollutants. The difference between this embodiment and Example 2 is that the organic pollutants are sulfamethoxazole, atrazine, tetracycline, methylene blue and N,N-dimethylformamide, and their initial concentrations are 15, 12, 2.5, 20 and 20 mg L - 1 The concentrations of various organic compounds in the bottom liquid and condensate were determined by high performance liquid chromatography. The results are as follows: Figure 5 shown.

[0048] Figure 5 The following is a graph showing the degradation effects of the interface evaporator prepared in Example 2 on different types of organic pollutants in the condensate and bottom liquid. Figure 5It can be seen that the interface evaporator prepared in Example 1 can still maintain an excellent catalytic degradation effect on different types of organic pollutants, which shows that the interface evaporator of the present invention has a wide range of applications and therefore has good practical application prospects.

Claims

1. An all-weather interface evaporator that can prevent the escape of volatile organic compounds and the production of concentrated water, characterized in that: The interface evaporator includes a catalyst-loaded evaporation layer, a water-transporting medium, and an inert metal. The catalyst-loaded evaporation layer serves as a cathode, and the inert metal serves as an anode. The anode is located below the water-transporting medium, and the water-transporting medium contacts the catalyst-loaded evaporation layer and the inert metal, respectively. The method for preparing the catalyst-loaded evaporation layer comprises the following steps: (1) Dispersing carbon nanotubes in a mixed acid solution of nitric acid and sulfuric acid, stirring at 78-85°C for 2-4 hours, letting it stand for 1-2 hours, washing the precipitate with ultrapure water, and filtering; then, freeze-drying the precipitate to obtain oxidized carbon nanotubes; (2) uniformly dispersing FeCl3•6H2O and oxidized carbon nanotubes in ethanol or isopropanol to obtain a mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate; wherein the mass ratio of ferric chloride hexahydrate to oxidized carbon nanotubes is 0.5-2:1; (3) spraying a mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate onto the surface of the carbon cloth substrate, and drying the mixture to obtain ferric chloride hexahydrate / oxidized carbon nanotubes / carbon cloth; (4) placing ferric chloride hexahydrate / carbon oxide nanotubes / carbon in a crucible, sealing it, and calcining it at 200-220°C for 1.5-2 hours to obtain a calcined evaporation layer; (5) Coating the surface of the calcined evaporation layer with a mixed solution of Nafion solution and water, and drying the mixture to obtain a catalyst-loaded evaporation layer; wherein the volume ratio of Nafion solution to water in the mixed solution of Nafion solution and water is 30-35:

100.

2. The preparation method according to claim 1, characterized in that The water transport medium is one or more of dust-free paper and cotton cloth, and the inert metal is ruthenium, iridium, titanium or platinum sheet.

3. The preparation method according to claim 1, characterized in that In step (1), the volume ratio of nitric acid to sulfuric acid in the mixed acid solution of nitric acid and sulfuric acid is 30-35:100; wherein the concentration of nitric acid is 15-17 mol / L, and the concentration of sulfuric acid is 17-19 mol / L; and the concentration of the carbon nanotubes in the mixed acid solution of nitric acid and sulfuric acid is 20-30 g / L.

4. The preparation method according to claim 1, characterized in that In step (2), the content of FeCl3•6H2O in the mixed solution of oxidized carbon nanotubes and ferric chloride hexahydrate is 3~12g / L, and the content of oxidized carbon nanotubes is 6~8g / L; the carbon cloth substrate is first rinsed with ethanol, then rinsed with deionized water, and dried to obtain a carbon cloth substrate.

5. The preparation method according to claim 1, characterized in that In step (5), the mass fraction of the Nafion solution is 4-6 wt%.

6. The method for preparing an interface evaporator according to any one of claims 1 to 5, characterized in that: The following steps are involved: The catalyst-loaded evaporation layer is placed parallel to the water transport medium, and the water transport medium is placed parallel to the middle of the catalyst-loaded evaporation layer and the anode. The water transport medium contacts the catalyst-loaded evaporation layer and the inert metal respectively to obtain an all-weather interface evaporator.

7. Use of the all-weather interface evaporator according to any one of claims 1 to 5 or the all-weather interface evaporator prepared by the preparation method according to claim 6 in organic wastewater.

8. The application according to claim 7, characterized in that: The application method comprises the following steps: In a three-electrode system, the catalyst-loaded evaporation layer is connected to the working electrode of the electrochemical workstation as the cathode, and the inert metal is connected to the counter electrode as the anode; one end of the water transport medium is placed in the organic wastewater, and the other end is placed in a container for collecting purified concentrated water, and sunlight is used to irradiate the catalyst-loaded evaporation layer to treat the wastewater.

9. The use according to claim 7 or 8, characterized in that: The applied voltage is -0.4 to -1.0 V; the pH of the wastewater is 3 to 9, and the pollutants in the organic wastewater are one or more of phenol, sulfamethoxazole, N,N-dimethylformamide, atrazine, dyes or antibiotics.

10. The use according to claim 7 or 8, characterized in that: The organic wastewater also contains anhydrous sodium sulfate, wherein the concentration of sodium sulfate is 0.04-0.05 mol / L; Or it further includes a reference electrode, wherein the reference electrode is Ag / AgCl.

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