Ecological floating bed based on full-spectrum photocatalytic energy storage material

Abstract

This invention discloses an ecological floating bed based on a full-spectrum photocatalytic energy storage material, comprising a floating bed frame, plants, planting baskets, and a photocatalytic energy storage component. The photocatalytic energy storage component carries a full-spectrum photocatalytic energy storage material with photogenerated electron storage and dark-state release functions. This ecological floating bed utilizes a full-spectrum photocatalytic energy storage material with a wide spectral response range and photogenerated electron storage and dark-state release functions, overcoming the technical bottlenecks of traditional ecological floating bed photocatalytic materials, such as narrow spectral response range, loss of purification capacity at night, and limited functionality preventing the recovery of low-concentration resources. It achieves full-spectrum utilization and all-weather purification, and can be widely applied to the ecological restoration of polluted surface water bodies and the recovery of low-concentration metal resources from mining tailings.

Description

Technical Field

[0001] This invention relates to an ecological floating bed, and more particularly to an ecological floating bed based on a full-spectrum photocatalytic energy storage material. Background Technology

[0002] Ecological floating beds are a technology for ecological restoration of polluted water bodies. Traditional ecological floating beds mainly rely on plant absorption and microbial degradation to purify water, but they have problems such as no purification capacity at night, low removal efficiency of recalcitrant organic matter, and limited functionality that prevents the recovery of low-concentration resources.

[0003] In my country's production of key metals and rare earths, mine tailings are characterized by "three lows, one high, and one dispersed": low biodegradability, low pollutant concentration, low light conditions, high treatment standards, and extremely dispersed useful components. This makes it difficult to apply traditional ecological floating beds to mine tailings treatment.

[0004] To address the aforementioned issues, patent application CN202511167693.8 discloses a photocatalytic-biofilm synergistic ecological floating bed. This bed utilizes a carbon fiber substrate loaded with tea polyphenol-modified TiO2-silver-based composite material, combined with UV-LED irradiation, enabling all-weather operation by utilizing sunlight during the day and UV-LED lamps at night. While photocatalysis can enhance the purification efficiency of the ecological floating bed, the photocatalytic material TiO2 only responds to ultraviolet light (accounting for approximately 5% of solar energy) and deactivates at night. Therefore, this technology still suffers from limitations such as insufficient energy self-sufficiency and low spectral utilization: nighttime photocatalysis relies entirely on external power to drive the UV-LED lamps, failing to overcome the inherent nighttime deactivation bottleneck of the material; modified TiO2 primarily responds to ultraviolet-visible light, with low infrared light utilization; and the system only focuses on pollutant degradation, without addressing low-concentration resource recovery.

[0005] The development of photocatalytic energy storage materials has provided new ideas for overcoming the above limitations. For example, the photocatalytic energy storage material Pt-H:WO3, which is rich in oxygen vacancy defects, not only extends the light absorption to the full spectrum of 300-1000 nm, but also captures and stores photogenerated electrons for a long time (>300 h) through defect energy levels. In the dark, the electrons are released through a Pt co-catalyst to drive the catalytic reaction, realizing "self-driven" all-weather pollutant purification without external energy, and recovering low-concentration valuable metals through photoelectron reduction.

[0006] However, existing WO3 photocatalytic materials face a dual technical bottleneck in practical applications: on the one hand, their conduction band position is too positive, relying on defect electrons to reduce O2 to generate active species, but the dissolved oxygen concentration in the aqueous phase is naturally insufficient, making it difficult to maintain dark-state activity after the light stops; on the other hand, nanoparticles are easy to lose and difficult to recycle, and the high temperature required for traditional loading and immobilization will destroy the activity of Pt co-catalyst, resulting in a serious decline in catalytic performance.

[0007] In summary, existing ecological floating beds suffer from problems such as insufficient energy self-sufficiency, low spectral utilization, lack of low-concentration resource recovery capacity, and poor loading effect of photocatalytic energy storage materials. Summary of the Invention

[0008] Purpose of the invention: The purpose of this invention is to provide an ecological floating bed based on full-spectrum photocatalytic energy storage materials, capable of purifying wastewater around the clock and realizing the recovery of low-concentration metal resources from mine tailings.

[0009] Technical solution: The ecological floating bed based on full-spectrum photocatalytic energy storage material includes a floating bed frame, plants, planting baskets and photocatalytic energy storage components. The photocatalytic energy storage components are characterized in that the photocatalytic energy storage components are loaded with full-spectrum photocatalytic energy storage materials that have the functions of storing photogenerated electrons and releasing them in the dark.

[0010] The full-spectrum photocatalytic energy storage material enables the ecological floating bed to have a wide spectral response range and to spontaneously release electrons to generate active oxygen species under light-free conditions. This overcomes the shortcomings of existing ecological floating beds that deactivate at night or rely on additional energy, and enables all-weather purification and low-concentration recovery of valuable metal resources.

[0011] The preferred full-spectrum photocatalytic energy storage material is a composite material of WO3 loaded with noble metal nanoparticles after hydrogen annealing, wherein the noble metal includes Pt, Pd, or Au. Pd is the most preferred noble metal. When Pt is used as a co-catalyst, a reduction temperature above 400°C is required for effective reduction of chloroplatinic acid, which easily leads to the thermal decay of unstable oxygen vacancy defects in hydrogen-treated WO3 (H:WO3). However, by selecting Pd as a co-catalyst, loading and calcination can be completed at a low temperature of 280-300°C, maximizing the retention of oxygen vacancy defects introduced by hydrogen annealing, thereby ensuring the material's photogenerated electron storage capacity. Simultaneously, Pd, as a relatively inexpensive platinum group metal, significantly reduces raw material costs, which is beneficial for large-scale engineering applications.

[0012] The preferred full-spectrum photocatalytic energy storage material is Pd-H:WO3. This material is rich in hydrogen-induced oxygen vacancies, which form defect energy levels in the band gap as electron trapping sites. This oxygen vacancy electron storage mechanism can efficiently release stored electrons through the Pd co-catalyst to drive the oxygen reduction reaction at night when there is no light, enabling the system to continuously generate active oxygen at night, thus overcoming the limitation of nighttime deactivation in traditional photocatalysis. Furthermore, the Pd-H:WO3 composite material overcomes the limitation of TiO2 only utilizing ultraviolet light, achieving full-spectrum light absorption, overcoming the low spectral utilization rate of existing ecological floating beds, improving ecological restoration efficiency, and realizing all-weather pollutant purification and low-concentration valuable metal resource recovery without external energy.

[0013] The loading of the full-spectrum photocatalytic energy storage material is 2-4 wt%.

[0014] The photocatalytic energy storage component is preferably a catalytic carbon fiber tube.

[0015] The catalytic carbon fiber tubes are preferably fixed to the floating bed frame using fasteners. Preferably, part of the carbon fiber tube is submerged in water and partially exposed to air, forming a gas-liquid-solid three-phase interface. The submerged section provides the photocatalytic reaction zone; the exposed gas phase section allows atmospheric O2 to diffuse directly to the catalyst, overcoming the limitation of dissolved oxygen in the liquid phase and continuously replenishing O2 through natural convection, achieving 24-hour continuous reaction. The micro-nano pores of the carbon fiber generate a capillary effect, forming a 2-3 cm thick gas-liquid-solid three-phase reaction zone.

[0016] The planting basket preferably includes a composite filler. The composite filler is preferably layered, with a bottom layer of bio-ceramic granules, a middle layer of volcanic rock, and an upper layer of manganese ore.

[0017] The present invention also provides the application of the ecological floating bed in the remediation of polluted water bodies or the recovery of low-concentration valuable metals from mining tailings.

[0018] The present invention also provides a method for preparing the aforementioned ecological floating bed, comprising the following steps:

[0019] S1. Heat-treat WO3 powder in a H2 / Ar mixed atmosphere to obtain H:WO3; immerse H:WO3 in chloropalladium acid solution, disperse it ultrasonically, evaporate it to dryness, and calcine it to obtain the full-spectrum photocatalytic energy storage material Pd-H:WO3;

[0020] S2. Load Pd-H:WO3 onto a support to obtain a catalytic support, i.e., a photocatalytic energy storage component;

[0021] S3. Assemble the photocatalytic energy storage component with the floating bed frame, plants, and planting baskets to obtain an ecological floating bed.

[0022] In S2, the preferred method for preparing the catalyst support is as follows: Pd-H:WO3 powder is mixed with ethanol, a binder is added and ultrasonically dispersed to obtain a suspension; the support is immersed in the suspension, vacuum-coated and then cured to obtain a photocatalytic energy storage component.

[0023] In S2, the optimal carrier is a carbon fiber tube, and the loading includes the following steps:

[0024] S21. Mix Pd-H:WO3 composite material powder with anhydrous ethanol at a solid-liquid ratio of 1:10, add PVB binder (solid content 3-5%), and ultrasonically disperse at 200 W for 30 min to obtain a uniform suspension.

[0025] S22. Immerse the braided carbon fiber tube with an outer diameter of 10-12 mm into the above suspension, place it in a vacuum coating device, evacuate to -0.09 MPa and hold for 30 s, release the vacuum and drain off the excess slurry.

[0026] S23. Place the coated carbon fiber tube in an 80℃ oven for 2 hours to cure the adhesive.

[0027] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The ecological floating bed based on full-spectrum photocatalytic energy storage material utilizes a full-spectrum photocatalytic energy storage material with a wide spectral response range and the functions of photogenerated electron storage and dark-state release, which solves the technical bottleneck of narrow spectral response range and loss of purification capacity at night in traditional ecological floating bed photocatalytic materials. It realizes full-spectrum utilization, all-weather purification and low-concentration metal resource recovery, and can be widely used in the ecological restoration of polluted surface water bodies and the recovery of metal resources in mine tailings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0030] Example 1

[0031] This embodiment provides an ecological floating bed based on a full-spectrum photocatalytic energy storage material, with the structure as follows: Figure 1 As shown, the system includes a floating bed frame 1, plants 2, a planting basket 3, and a photocatalytic energy storage component 4. The photocatalytic energy storage component 4 is a catalytic carbon fiber tube, which is fixed to the floating bed frame 1 by a fastener 5. The catalytic carbon fiber tube is loaded with a full-spectrum photocatalytic energy storage material. The photocatalytic energy storage material is Pd-H:WO3, which has the functions of storing photogenerated electrons and releasing them in the dark.

[0032] Example 2

[0033] This embodiment provides a method for preparing the photocatalytic energy storage material Pd-H:WO3 in Example 1.

[0034] Commercial WO3 powder was placed in a tube furnace and heated to 550°C at a rate of 5°C / min under a 5% H2 / Ar mixed gas atmosphere (flow rate 135 mL / min), held at that temperature for 2 h, and then naturally cooled to room temperature to obtain hydrogen-annealed WO3 (H:WO3, mainly W). 20 O 56 Mutually).

[0035] The H:WO3 powder was immersed in a 0.05 M chloropalladium acid solution, ultrasonically dispersed at 200 W for 30 min, evaporated to dryness at 80°C, and then calcined at 300°C for 2 h in a tube furnace under a 5% H2 / Ar mixed gas atmosphere (flow rate 135 mL / min) to obtain a Pd-H:WO3 composite material with a Pd loading of approximately 3 wt.%.

[0036] Example 3

[0037] In this embodiment, the photocatalytic energy storage component 4 in Example 1 is prepared using the photocatalytic energy storage material Pd-H:WO3 obtained in Example 2.

[0038] 11 mm outer diameter braided carbon fiber tubes were immersed in a Pd-H:WO3 suspension (solid-liquid ratio 1:10, containing PVB), vacuum coated (-0.09 MPa, 30 s), and cured at 80°C, with a load density of approximately 30 g / m³. 2 .

[0039] Example 4

[0040] This embodiment provides a method for assembling the ecological floating bed described in Embodiment 1.

[0041] A lightweight foam board measuring 60 cm × 60 cm was used as the floating bed frame 1, with four planting holes spaced 20 cm apart. Polypropylene planting baskets 3 (10 cm in diameter, 20 cm in height) with a bottom and sidewall perforation rate ≥30% were selected and filled with composite filler. The composite filler consisted of bio-ceramic granules (3-5 mm, 5 cm), volcanic rock (5-10 mm, 5 cm), and manganese ore (10-20 mm, 8 cm) in a volume ratio of 3:2:5, filled sequentially into the planting baskets 3 from bottom to top, with a total filling height of approximately 18 cm. Canna seedlings with a height of 30-40 cm were selected as emergent plants 2. After washing the roots, they were planted into the planting baskets 3, ensuring full contact between the roots and the composite filler. The planting baskets 3 were then inserted into the planting holes of the floating bed frame 1.

[0042] Four catalytic carbon fiber tubes prepared in Example 3 were taken and fixed to the four corners of the floating bed frame 1 vertically with stainless steel fasteners 5. Then, the catalytic carbon fiber tubes were bent 90° at the waterline of the floating bed frame 1 so that they were tightly attached to the four sides of the floating bed frame 1 and partially floated on the water surface, forming a gas-liquid-solid three-phase reaction interface. Each carbon fiber tube was 40 cm long, of which 12 cm was completely exposed to the air and the remaining 28 cm was located at the waterline of the floating bed frame 1.

[0043] Example 5

[0044] This embodiment uses the ecological floating bed described in Embodiment 1 to purify landscape water bodies with low pollution load.

[0045] Experimental methods: (1) Preparation of simulated landscape water: COD 15±2 mg / L, TN 0.8±0.1 mg / L, ammonia nitrogen 0.3±0.05 mg / L, pH 7.0±0.2. (2) Water purification: Simulated landscape water was injected into a 120 L polyethylene water tank. The ecological floating bed described in Example 1 was placed in the water tank, with a coverage rate of 40%. Coverage rate = floating bed frame area / water surface area of ​​the tank. The experimental period was 12 days, using a static operation mode, with water samples collected every 3 days. COD concentration was measured at 8, 12, and 18 on days 0, 3, 6, 9, and 12. At the same time, COD concentration was measured at 0 and 8 on days 1, 4, 7, and 10 to evaluate the nighttime purification capacity. COD was determined by the dichromate method.

[0046] Experimental results: The ecological floating bed provided by this invention achieved a COD removal rate of 45%, and maintained 35% of the daytime degradation rate even at night (under dark conditions), verifying the storage-release effect of photogenerated electrons; while traditional floating beds had almost no purification capacity at night. During operation, no obvious pollution layer appeared on the surface of the catalytic tube, and plants grew well.

[0047] Example 6

[0048] This embodiment uses the ecological floating bed described in Example 1 to purify moderately eutrophic water bodies.

[0049] Experimental methods: (1) Prepare simulated aquaculture wastewater: COD 40±3 mg / L, TN 15±1 mg / L, TP 1.5±0.2 mg / L, and add 500 μg / L of sulfamethoxazole (SMX), a recalcitrant organic compound. (2) Water purification: Inject simulated aquaculture wastewater into a 120 L water tank. Place the ecological floating bed described in Example 1 in the water tank and set the coverage rate to 40%. Due to the imbalance of C / N ratio in eutrophic water, it is difficult to build microbial communities. Therefore, before formal operation, the system is first subjected to natural biofilm acclimatization for 10 days. During this period, carbon source (glucose, maintaining a C / N ratio of 5:1) is supplemented every 3 days to promote biofilm maturation. The formal operation cycle is 21 days, using a static operation mode. Water samples are collected every 7 days at 8, 12, and 18:00 on days 0, 7, 14, and 21. Simultaneously, samples are collected at 0 and 8:00 on days 1, 8, 15, and 22 to determine the concentrations of COD, TN, TP, and SMX. COD is determined using the dichromate method, TN using alkaline potassium persulfate digestion-UV spectrophotometry, TP using ammonium molybdate spectrophotometry, and SMX using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) to evaluate its pollutant purification capacity.

[0050] Experimental results: The ecological floating bed provided by this invention achieved a COD removal rate of 58%, a TN removal rate of 38%, a TP removal rate of 32%, and a SMX removal rate of 42%. Among them, SMX maintained a removal rate of approximately 25% at night.

[0051] Example 7

[0052] This embodiment uses the ecological floating bed described in Embodiment 1 to purify mine tailings.

[0053] Experimental methods: (1) Prepare simulated mine tailings water: COD 50±5 mg / L, TN 15±1 mg / L, TP 1.0±0.2 mg / L, and add low concentration of valuable metal ions: Cu 2+ 5.0±0.2 mg / L, Zn 2+ 10.0±0.2 mg / L, Mn 2+ 10.0±0.5 mg / L, pH 6.5±0.3. (2) Water purification: Simulated mine tailings water was injected into a 120 L water tank. The ecological floating bed described in Example 1 was placed in the water tank, with a coverage rate of 40%. The system biofilm acclimatization was the same as in Example 6. The test period was 14 days, and a static operation mode was adopted. Water samples were collected every 3 days. Samples were taken at 8, 12, and 18 on days 0, 3, 6, 9, 12, and 14, respectively. At the same time, samples were taken at 0 and 8 on days 1, 4, 7, 10, and 14 to determine the concentrations of COD, TN, TP, and metal ions. This was to evaluate the nighttime purification and metal recovery capabilities. The methods for determining COD, TN, and TP were the same as in Example 6. (3) Metal enrichment and recovery verification: After the operation was completed, the catalytic carbon fiber tube was removed, the surface was rinsed with deionized water to remove loose attachments, dried at 60℃ to constant weight, and the weight gain was recorded. Subsequently, the deposited metal was recovered using an acid leaching method: the dried catalytic carbon fiber tube was placed in 100 mL of 2 mol / L HNO3 solution, heated in a water bath at 80℃ for 2 h, and then subjected to ultrasonic-assisted leaching for 30 min to completely dissolve the surface deposited metal. After filtering the extract through a 0.45 μm filter membrane, the contents of Cu, Zn, and Mn were determined by ICP-OES, and the metal enrichment and recovery rate of a single carbon fiber tube were calculated.

[0054] Experimental results: The ecological floating bed provided by this invention has a positive effect on Cu 2+ The removal rate reached 92%, Zn 2+ The removal rate reached 48%, Mn 2+ The removal rate reached 40%, and the removal of Cu at night was also effective. 2+ It maintains a removal rate of approximately 15%; simultaneously, the COD removal rate reaches 60%, the TN removal rate 45%, and the TP removal rate 32%. In the initial stage of operation, photogenerated electrons are preferentially used for metal reduction, and COD degradation is slightly slower; as the metal ion concentration decreases, the COD degradation rate gradually accelerates.

[0055] Metal enrichment and recovery determination: The average weight gain per meter of carbon fiber tube was 1.5 g / m, determined by the dry weighing method. ICP-OES analysis after acid extraction with 2 mol / L HNO3 showed that the total amount of Cu, Zn, and Mn deposited on the surface was 1.1 g / m. The difference between the weighing method and the total metal recovery method indicates that the weight gain, in addition to the target metals, also contains a small amount of co-precipitated impurity ions and surface-bound water, confirming that the metal ions were successfully reduced and enriched on the material surface. The catalyst support can be reused after rinsing with deionized water and drying.

Claims

1. An ecological floating bed based on a full-spectrum photocatalytic energy storage material, comprising a floating bed frame (1), plants (2), a planting basket (3), and a photocatalytic energy storage component (4), characterized in that, The photocatalytic energy storage component (4) is loaded with a full-spectrum photocatalytic energy storage material that has the functions of storing photogenerated electrons and releasing them in the dark.

2. The ecological floating bed according to claim 1, characterized in that, The full-spectrum photocatalytic energy storage material is a composite material of WO3 loaded with noble metal nanoparticles after hydrogen annealing, wherein the noble metal includes Pt, Pd or Au.

3. The ecological floating bed according to claim 2, characterized in that, The full-spectrum photocatalytic energy storage material is Pd-H:WO3.

4. The ecological floating bed according to claim 1, characterized in that, The loading of the full-spectrum photocatalytic energy storage material is 2-4 wt%.

5. The ecological floating bed according to claim 1, characterized in that, The photocatalytic energy storage component (4) is a catalytic carbon fiber tube.

6. The ecological floating bed according to claim 5, characterized in that, The catalytic carbon fiber tube is fixed to the floating bed frame (1) by a fastener (5).

7. The ecological floating bed according to claim 1, characterized in that, The planting basket (3) includes composite filler.

8. The application of the ecological floating bed according to any one of claims 1-7 in the remediation of polluted water bodies or the recovery of low-concentration valuable metals from mining tailings.

9. A method for preparing the ecological floating bed according to claim 3, characterized in that, Includes the following steps: S1. Heat-treat WO3 powder in a H2 / Ar mixed atmosphere to obtain H:WO3; immerse H:WO3 in chloropalladium acid solution, disperse it ultrasonically, evaporate it to dryness, and calcine it to obtain the full-spectrum photocatalytic energy storage material Pd-H:WO3; S2. Load Pd-H:WO3 onto the support to obtain the catalytic support, i.e., the photocatalytic energy storage component (4). S3. Assemble the photocatalytic energy storage component (4) with the floating bed frame (1), plants (2), and planting basket (3) to obtain an ecological floating bed.

10. The preparation method according to claim 9, characterized in that, In S2, the method for preparing the catalyst support is as follows: Pd-H:WO3 powder is mixed with ethanol, and a binder is added and ultrasonically dispersed to obtain a suspension; the support is immersed in the suspension, vacuum dip-coated and then cured to obtain a photocatalytic energy storage component (4).

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