Solar photo-thermal foam for treatment of salt-containing organic wastewater and method of preparation thereof

Abstract

The application discloses a solar photo-thermal foam for treating salt-containing organic wastewater and a preparation method thereof. The application solves the problems of poor desalination effect, low degradation ability for organic pollutants, especially volatile organic pollutants, and easy concentration of organic pollutants in the bottom liquid in the process of treating salt-containing organic wastewater by solar photo-thermal treatment. The application comprises the following steps: preparing a photo-thermal foam by loading a copper-cobalt binary metal catalyst on a nickel-based metal foam, and using the photo-thermal foam to treat water in a device for treating salt-containing organic wastewater by solar photo-thermal treatment. The porous foam substrate is used to construct a high-performance photo-thermal foam with a special morphology, and under the synergistic action of a multi-metal catalytic system, efficient desalination and catalytic persulfate degradation of organic pollutants in the bottom liquid and condensate are realized in the process of treating salt-containing organic wastewater by solar photo-thermal treatment, so that high-quality pure water is obtained. In addition, the photo-thermal foam catalyst is simple to recover and can effectively inhibit metal leaching toxicity, and has good repeated stability.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a solar thermal foam for treating saline organic wastewater and its preparation method. Background Technology

[0002] Water pollution has become increasingly prominent due to rapid population growth and industrial development. Large quantities of wastewater containing organic pollutants are discharged into lakes and seas. The diversity of industrial activities has led to highly complex compositions of the discharged water bodies. The organic and salt pollutants in this saline organic wastewater are non-biodegradable, and traditional treatment processes are no longer sufficient to meet the demand for high-quality freshwater. Solar interfacial evaporation technology is considered one of the most promising freshwater production technologies due to its environmental friendliness and low investment cost. However, when saline bodies are contaminated with organic matter, these pollutants concentrate in the bottom liquid or condensate during the interfacial evaporation process, posing a threat to the environment and human health. Therefore, it is essential to develop a highly efficient technology for simultaneous desalination and degradation of organic pollutants.

[0003] Advanced oxidation technologies based on persulfate possess advantages such as long half-life, high redox potential, and strong selectivity. In particular, due to the generation of highly reactive oxygen species, they have been widely used in the treatment of organic pollutants. However, the catalysts used to activate persulfate are difficult to recover in water, and cobalt-based catalysts, one of the most efficient transition metals for activating persulfate, exhibit high leaching toxicity. Therefore, it is urgent to address the problems of low catalytic activity and difficulty in catalyst recovery.

[0004] In summary, there is an urgent need to develop a treatment method for organic wastewater treatment processes that suffer from poor desalination, poor treatment of organic pollutants, especially volatile organic pollutants, and the concentration of organic pollutants in the bottom liquid. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a solar thermal foam for treating saline organic wastewater and its preparation method. This invention loads an inherently polar copper-cobalt binary metal catalyst onto a porous nickel-based metal foam, developing a solar thermal foam that simultaneously desalinates and degrades organic pollutants. This effectively solves the problem of difficult catalyst recovery and achieves highly efficient treatment of saline organic wastewater through the synergistic effect of the multi-metal system. The solar thermal foam prepared by this invention exhibits excellent desalination effects on saline organic wastewater and also demonstrates good catalytic effects on persulfate, effectively degrading organic pollutants in the wastewater simultaneously. Furthermore, due to its full contact with the bottom liquid, it overcomes the shortcomings of traditional solar interfacial evaporation technology, which has poor degradation effects on organic pollutants in the bottom liquid and condensate.

[0006] To achieve the above objectives, the present invention provides a method for preparing solar thermal foam for treating saline organic wastewater, the specific preparation method comprising the following steps:

[0007] (1) The nickel-based metal foam is successively immersed in hydrochloric acid, sodium hydroxide aqueous solution and anhydrous ethanol for 0.5-2 hours, then washed with deionized water and dried to obtain clean nickel-based metal foam free of impurities; wherein the concentration of hydrochloric acid is 0.1-10M, preferably 4-6M, and the concentration of sodium hydroxide aqueous solution is 1-3M.

[0008] (2) Preparation of mixed solution A: Urea and ammonium fluoride are added to deionized water and stirred for 0.5 to 2 hours at a stirring speed of 600 to 1000 rpm to obtain mixed solution A; wherein the concentration of urea and ammonium fluoride is 0.05 to 2 M, preferably 0.10 to 0.20 M, and the molar ratio of urea to ammonium fluoride is 0.8 to 1.2:1, preferably 1:1;

[0009] (3) Preparation of a mixed solution B of cobalt salt and copper salt: The cobalt salt and copper salt are stirred with the above mixed solution A for 0.5 to 2 hours at a stirring speed of 600 to 1000 rpm to obtain a mixed solution B of cobalt salt and copper salt; wherein, the mass ratio of cobalt salt to copper salt is 0.25 to 4:1, preferably 2:1, and the ratio of the total amount of cobalt salt and copper salt to mixed solution A is 0.05 to 0.15 mol: 1 L, preferably 0.08 to 0.12 mol: 1 L;

[0010] (4) The nickel-based metal foam obtained in step (1) above is immersed in the mixed solution B obtained in step (3) above, and a hydrothermal reaction is carried out at 110-130°C for 6.0-12.0 h to obtain nickel-based metal foam loaded with bimetallic intermediate;

[0011] (5) The nickel-based metal foam with bimetallic intermediate obtained in step (4) above is placed in a tube furnace and calcined with air. The calcination temperature is 250-400℃, the heating rate is 2-10℃ / min, and the calcination time is 1-4h. After cooling, nickel-based metal foam with copper-cobalt binary metal catalyst is obtained.

[0012] The nickel-based metal foam is one of foamed nickel or foamed nickel iron.

[0013] The cobalt salt is one or more of cobalt chloride, cobalt sulfate, and cobalt nitrate, and the copper salt is one or more of copper chloride, copper sulfate, and copper nitrate.

[0014] A second aspect of the present invention provides a solar thermal foam for treating saline organic wastewater obtained by the above preparation method.

[0015] A third aspect of this invention provides the application of the above-mentioned solar thermal foam in the treatment of saline organic wastewater. The application method includes the following steps:

[0016] Under stirring conditions, persulfate is added to saline organic wastewater to form a mixed solution. The solar thermal foam is then tilted and inserted into the mixed solution, with some of the foam exposed to air and the remainder immersed. The foam is then irradiated with sunlight for 3-12 hours to treat the saline organic wastewater, achieving simultaneous desalination and degradation of organic pollutants. The highly catalytic solar thermal foam degrades organic pollutants in the saline wastewater by catalyzing the persulfate in the mixed solution. Simultaneously, the foam surface absorbs solar energy, converting it into heat to heat the mixed solution, causing water to vaporize and pass through the foam. Salt pollutants are retained, thus achieving desalination of the saline organic wastewater and obtaining high-quality condensed freshwater.

[0017] The concentration of the persulfate is 0.001–0.005 M, preferably 0.002–0.004 M;

[0018] The persulfate is one or both of potassium peroxymonosulfate and potassium perdisulfate;

[0019] The salinity of the saline organic wastewater is 0.1% to 5%, preferably 2% to 4%;

[0020] The pH of the mixture is 3-8, preferably 6-7;

[0021] The solar radiation intensity is 50-1000 kW / m 2 Preferably 1000kW / m 2 ;

[0022] The temperature of the mixture is between 20 and 40°C.

[0023] The tilt angle is the angle between the solar thermal foam and the horizontal plane of the mixture, and the angle ranges from 10 to 80°, preferably 45°; the ratio of the area of ​​the solar thermal foam exposed to air to the area immersed in the mixture is 0.25 to 4:1, preferably 1:1, that is, half of the solar thermal foam is exposed to air and half of the solar thermal foam is immersed in the mixture.

[0024] The organic pollutant is one or more of phenol, aniline, sulfamethoxazole, N,N-dimethylformamide, dyes, and antibiotics.

[0025] After treating saline organic wastewater, the solar thermal foam is soaked in deionized water for 1-2 hours and then dried. It is then placed in a tube furnace and calcined with air. The calcination temperature is 250-400℃, the heating rate is 2-10℃ / min, and the calcination time is 1-4 hours. After cooling, the regenerated solar thermal foam is obtained.

[0026] This invention involves preparing photothermal foam by loading a copper-cobalt binary metal catalyst onto a nickel-based metal foam, and then using it for water treatment in a solar photothermal treatment device for saline organic wastewater. High-performance photothermal foam with a unique morphology is constructed using a porous foam substrate. Through the synergistic effect of a multi-metal catalytic system, simultaneous and efficient desalination and catalytic persulfate degradation of organic pollutants in the bottom liquid and condensate are achieved during the solar photothermal treatment of saline organic wastewater, yielding high-quality pure water. Furthermore, this photothermal foam catalyst is easy to recover, effectively inhibits metal leaching toxicity, and exhibits good repeatability and stability, showing broad application prospects in the field of water treatment.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The photothermal foam prepared in this invention can achieve efficient solar wastewater desalination and catalytic degradation of organic pollutants in wastewater by persulfate to obtain high-quality freshwater during the treatment of saline organic wastewater.

[0029] (2) The photothermal foam prepared in this invention has a good catalytic effect on persulfate through the synergistic effect between copper, cobalt and nickel multimetals. Compared with other traditional solar interface evaporation technologies, it makes up for the deficiency of being unable to solve the concentration of organic pollutants in the bottom liquid and condensate.

[0030] (3) The photothermal foam prepared in this invention can be tightly bonded with copper-cobalt bimetal, effectively inhibiting the leaching of cobalt metal.

[0031] (4) The photothermal foam prepared in this invention has good repeatability and can be recycled multiple times in a high efficiency.

[0032] (5) The photothermal foam prepared in this invention has a simple structure, high economic benefits, is suitable for mass production, is conducive to industrialization, and has broad application prospects. Attached Figure Description

[0033] The present invention will be further described in conjunction with the accompanying drawings and embodiments.

[0034] Figure 1 The image shows a scanning electron microscope (SEM) image of the prepared photothermal foam.

[0035] Figure 2 This is a schematic diagram of the structure of the prepared photothermal foam evaporation device.

[0036] Figure 3The diagram shows the effects of different photothermal foams on desalination and degradation of organic pollutants in saline organic wastewater.

[0037] Figure 4 The image shows the effect of the prepared photothermal foam in the recycling treatment of saline organic wastewater.

[0038] Figure 5 A comparison of the concentration of cobalt ions in the bottom solution after the reaction of the prepared photothermal foam and the photothermal foam without copper-based catalyst.

[0039] Figure 6 A comparison of the effects of the prepared photothermal foam on the treatment of saline organic wastewater using traditional solar interface evaporation technology. Detailed Implementation

[0040] 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 as described in the claims of the present invention, as well as other modifications that do not depart from the essence of the present invention, should be included within the protection scope of the present invention.

[0041] The following describes specific embodiments of the present invention in conjunction with the technical solutions, but the present invention is not limited to the following embodiments.

[0042] Example 1

[0043] A solar thermal foam for treating saline organic wastewater comprises the following steps: Nickel foam is sequentially immersed in 5M hydrochloric acid, 2M sodium hydroxide aqueous solution, and anhydrous ethanol for 1 hour, followed by washing with deionized water and drying to obtain clean, impurity-free nickel foam. 0.15M urea and 0.15M ammonium fluoride are added to 70 mL of deionized water and stirred vigorously at 800 rpm for 1 hour to prepare mixed solution A. Cobalt nitrate hexahydrate and copper nitrate trihydrate are used as cobalt and copper sources, respectively. 0.06M cobalt source and 0.03M copper source are added to mixed solution A and stirred at 800 rpm for 1 hour to prepare mixed solution B. After stirring, the clean, impurity-free nickel foam is immersed in mixed solution B and placed together in a reaction vessel for a hydrothermal reaction at 120°C for 10 hours. After the reaction, the mixture is cooled to room temperature to obtain nickel foam loaded with a bimetallic intermediate. Nickel foam loaded with a bimetallic intermediate was placed in a tube furnace and calcined under air. The calcination temperature was 300℃, the heating rate was 4℃ / min, and the calcination time was 3h. After cooling, nickel foam loaded with a copper-cobalt binary metal catalyst was obtained.

[0044] Figure 1 The image shows a scanning electron microscope (SEM) image of the prepared photothermal foam. Figure 1It can be seen that Example 1 has abundant porosity, which helps to uniformly load the copper-cobalt binary metal catalyst onto the photothermal foam. At the same time, the special sea urchin morphology, with its porous needle-like hierarchical structure, helps to enhance the photothermal conversion performance.

[0045] Example 2

[0046] The difference between this embodiment and Example 1 is that only 0.09M of cobalt source is added to the mixed solution A, while the rest is the same as in Example 1, to prepare a photothermal foam loaded with cobalt oxide.

[0047] Example 3

[0048] The difference between this embodiment and Example 1 is that only 0.09M of copper source is added to the mixed solution A, while the rest is the same as in Example 1, to prepare a photothermal foam loaded with copper oxide.

[0049] Example 4

[0050] The difference between this embodiment and Example 1 is that no cobalt source or copper source needs to be added to the mixed solution A. Otherwise, it is the same as Example 1, and nickel-based metal photothermal foam is prepared.

[0051] Example 5

[0052] Applications of different solar thermal foams to saline organic wastewater. Under stirring conditions, potassium persulfate was added to 30 mL of saline organic wastewater to form a mixed solution (temperature and pH were not adjusted; solution temperature was 25°C, pH was 6.0). Solar thermal foams from Examples 1, 2, 3, and 4 were tilted and inserted into the mixed solution, with half exposed to air and half immersed in the mixed solution. The solar thermal foams were then irradiated with sunlight for 8 hours to treat the saline organic wastewater. Figure 2 This is a schematic diagram of the prepared photothermal foam evaporation device. The concentration of potassium persulfate is 0.003M; the angle between the photothermal foam and the horizontal plane of the mixed liquid is 45°; and the ratio of the area of ​​the photothermal foam exposed to air to the area immersed in the mixed liquid is 1:1. The solar radiation intensity is 1000 kW / m². 2 The salinity of the saline organic wastewater was 3.5%, and the concentration of the organic pollutant phenol was 20 mg / L. A control group (referred to as the persulfate-only group) was used to treat the saline organic wastewater without the use of photothermal foam. The removal rate of salt pollutants and the concentration of phenol in the bottom liquid and condensate were determined using liquid chromatography and ICP-MS. The desalination rate and degradation rate were calculated, and the results are shown below. Figure 3 As shown. By Figure 3It is evident that the photothermal foam of this invention exhibits highly efficient desalination, achieving a desalination rate of 99%. Simultaneously, it achieves degradation rates of 95.5% and 94.8% for the organic pollutant phenol in the bottom liquid and condensate, respectively. This indicates that compared to photothermal foams loaded with only a single metal or without metals, the multi-metal approach produces a significant synergistic effect, enhancing the catalytic ability against persulfate and thus improving the degradation capacity for organic pollutants.

[0053] Example 6

[0054] After treating saline organic wastewater with the solar thermal foam prepared in Example 1, the foam was soaked in deionized water for 1 hour, dried, and then calcined in a tube furnace under air. The calcination temperature was 300°C, the heating rate was 4°C / min, and the calcination time was 3 hours. After cooling, regenerated solar thermal foam was obtained. Under stirring conditions, potassium persulfate was added to 30 mL of saline organic wastewater to form a mixed solution (temperature and pH not adjusted; solution temperature was 25°C, pH was 6.0). The solar thermal foam from Examples 1 and 2 was tilted and inserted into the mixed solution, with half exposed to air and half immersed in the solution. The foam was then irradiated with sunlight for 8 hours to treat the saline organic wastewater. The concentration of potassium persulfate was 0.003 M; the angle between the solar thermal foam and the horizontal plane of the mixed solution was 45°; and the ratio of the area of ​​the solar thermal foam exposed to air to the area immersed in the mixed solution was 1:1. The solar intensity was 1000 kW / m². 2 The salinity of the saline organic wastewater was 3.5%, and the concentration of the organic pollutant phenol was 20 mg / L. The previous operation was repeated for a total of 3 cycles. The removal rate of salt pollutants, the concentration of phenol in the bottom liquid and condensate, and the concentration of cobalt ions in the bottom liquid were determined using liquid chromatography and ICP-MS. The desalination rate and degradation rate were calculated, and the results are as follows: Figure 4 As shown.

[0055] Figure 4 This is an illustration of the effect of recycling saline organic wastewater. Figure 4 It can be seen that even after being recycled three times, the photothermal foam in Example 1 still exhibits efficient desalination and degradation of organic pollutants, thus demonstrating that the photothermal foam of the present invention has good stability and regenerability.

[0056] Figure 5 This is a comparison chart of cobalt ion concentrations in the bottom solution after the reaction. Figure 5 It is evident that the leaching amount of cobalt in the base solution of the photothermal foam in this invention is significantly less than that of the photothermal foam without a copper-based catalyst. This indicates that the photothermal foam in this invention can effectively inhibit the leaching of cobalt metal in the solution by utilizing the tight bonding of multiple metals, thereby reducing metal leaching toxicity.

[0057] Example 7

[0058] The degradation of saline organic wastewater by different tilt angles. Under stirring conditions, potassium persulfate was added to 30 mL of saline organic wastewater to form a mixed solution (temperature and pH not adjusted, solution temperature 25℃, pH 6.0). The solar thermal foam from Example 1 was tilted and inserted into the mixed solution, half exposed to air and half immersed in the solution. The solar thermal foam was then irradiated with sunlight for 8 hours to treat the saline organic wastewater. The concentration of potassium persulfate was 0.003 M; the angle between the solar thermal foam and the horizontal plane of the mixed solution was 45°; and the ratio of the area of ​​the solar thermal foam exposed to air to the area immersed in the mixed solution was 1:1. The solar intensity was 1000 kW / m². 2 The salinity of the saline organic wastewater was 3.5%, and the concentration of the organic pollutant phenol was 20 mg / L (denoted as the inclined type). In contrast, the angle between the photothermal foam and the horizontal plane of the mixed liquid was 0°, and only Example 1 utilized hydrophilic melamine foam floating on the surface of the mixed liquid (denoted as the conventional type). The removal rate of salt pollutants, the concentration of organic pollutant phenol in the bottom liquid and condensate were determined using liquid chromatography and ICP-MS. The desalination rate and degradation rate were calculated, and the results are as follows: Figure 6 As shown. By Figure 6 It is known that the photothermal foam in this invention has excellent desalination effect on saline organic wastewater, and can also efficiently degrade organic pollutants such as phenol in the bottom liquid and condensate. Compared with traditional solar interface evaporation technology, it makes up for the defect that it cannot effectively degrade organic pollutants in the bottom liquid and condensate.

[0059] Example 8

[0060] Under stirring conditions, potassium persulfate was added to 30 mL of saline organic wastewater to form a mixed solution (temperature and pH not adjusted; solution temperature 25°C, pH 6.0). The solar thermal foam from Example 1 was tilted and inserted into the mixed solution, with half exposed to air and half immersed. The solar thermal foam was then irradiated with sunlight for 8 hours to treat the saline organic wastewater. The concentration of potassium persulfate was 0.003 M; the angle between the solar thermal foam and the horizontal plane of the mixed solution was 45°; and the ratio of the area of ​​the solar thermal foam exposed to air to the area immersed in the mixed solution was 1:1. The solar intensity was 1000 kW / m². 2 The salinity of the saline organic wastewater was 3.5%, and the concentration of the organic pollutant sulfamethoxazole was 20 mg / L. The removal rate of saline pollutants and the concentration of sulfamethoxazole in the bottom liquid and condensate were determined using liquid chromatography and ICP-MS. The desalination rate and degradation rate were calculated.

[0061] The photothermal foam of this invention achieves a desalination rate of 99% for saline organic wastewater, while simultaneously achieving a degradation rate of 93.9% for sulfamethoxazole, an organic pollutant, in the bottom liquid and condensate. This demonstrates that the present invention has highly efficient desalination and organic pollutant degradation effects and wide applicability.

Claims

1. An application of solar thermal foam in the treatment of saline organic wastewater, characterized in that, The application method includes the following steps: Under stirring conditions, persulfate is added to saline organic wastewater to form a mixed solution; the solar thermal foam is tilted and inserted into the mixed solution, partially exposed to the air and partially immersed in the mixed solution, and the solar thermal foam is irradiated with sunlight for 3-12 hours to treat the saline organic wastewater. The method for preparing the solar thermal foam includes the following steps: (1) The nickel-based metal foam was soaked in hydrochloric acid, sodium hydroxide aqueous solution and anhydrous ethanol for 0.5-2 h in sequence, and then washed with deionized water and dried to obtain clean nickel-based metal foam without impurities; (2) Preparation of mixed solution A: Add urea and ammonium fluoride to deionized water and stir for 0.5-2 h at a stirring speed of 600-1000 rpm to obtain mixed solution A; wherein the concentration of urea and ammonium fluoride is 0.05-2 M and the molar ratio of urea to ammonium fluoride is 0.8-1.2:1; (3) Preparation of a mixed solution B of cobalt salt and copper salt: Stir the cobalt salt and copper salt with the above mixed solution A for 0.5-2 h at a stirring speed of 600-1000 rpm to obtain a mixed solution B of cobalt salt and copper salt; wherein, the mass ratio of cobalt salt to copper salt is 0.25-4:1, and the ratio of the total amount of cobalt salt and copper salt to mixed solution A is 0.05-0.15 mol:1 L; (4) The nickel-based metal foam obtained in step (1) above is immersed in the mixed solution B obtained in step (3) above, and a hydrothermal reaction is carried out at 110~130 ºC for 6.0-12.0 h to obtain nickel-based metal foam loaded with bimetallic intermediate; (5) The nickel-based metal foam with bimetallic intermediate obtained in step (4) above is placed in a tube furnace and calcined with air. The calcination temperature is 250~400 ºC, the heating rate is 2~10 ºC / min, and the calcination time is 1~4 h. After cooling, nickel-based metal foam with copper-cobalt binary metal catalyst is obtained. In step (3), the cobalt salt is one or more of cobalt chloride, cobalt sulfate, and cobalt nitrate, and the copper salt is one or more of copper chloride, copper sulfate, and copper nitrate.

2. The application according to claim 1, characterized in that, In step (1), the nickel-based metal foam is either nickel foam or nickel-iron foam, the concentration of the hydrochloric acid is 0.1~10 M, and the concentration of the sodium hydroxide aqueous solution is 1~3 M.

3. The application according to claim 1, characterized in that, The concentration of the persulfate is 0.001~0.005 M; the persulfate is one or both of potassium peroxymonosulfate and potassium persulfate. The salinity of the saline organic wastewater is 0.1% to 5%; The pH of the mixture is 3-8; The solar light intensity is 50-1000 kW / m 2 ; The temperature of the mixture is between 20 and 40 °C.

4. The application according to claim 1, characterized in that, The tilt angle is the angle between the solar thermal foam and the horizontal plane of the mixed liquid, and the angle ranges from 10 to 80°; the ratio of the area of ​​the solar thermal foam exposed to air to the area immersed in the mixed liquid is 0.25 to 4:

1.

5. The application according to claim 1, characterized in that, The organic pollutants are phenol or sulfamethoxazole.

6. The application according to claim 1, characterized in that, After treating saline organic wastewater, the solar thermal foam is soaked in deionized water for 1-2 hours and then dried. It is then placed in a tube furnace and calcined with air. The calcination temperature is 250-400 ºC, the heating rate is 2-10 ºC / min, and the calcination time is 1-4 hours. After cooling, the regenerated solar thermal foam is obtained.

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