Self-driven interface photocatalytic membrane reactor and preparation method thereof

Abstract

The invention discloses a self-driven interface photocatalytic membrane reactor and a preparation method thereof. The device comprises a hydrophilic photocatalytic membrane loaded with a photocatalyst, a feeding box and a collecting box are arranged on the two sides of the hydrophilic photocatalytic membrane respectively, and the feeding box is higher than the collecting box; one end of the hydrophilic photocatalytic membrane is arranged in the feeding box, and the other end of the hydrophilic photocatalytic membrane is arranged in the collecting box. The material liquid in the feeding box generates a siphon effect through the hydrophilic photocatalytic membrane, the material liquid is driven to continuously flow and enter the collecting box, additional energy input is not needed, and the device has the advantages of being low in energy consumption, high in degradation rate and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalytic film reactors, in particular to a self-driven interface photocatalytic film reactor and a preparation method thereof. Background Art

[0002] Water resources are the most important natural resources for human beings. Industrial production activities not only consume a lot of water, but also produce industrial wastewater containing organic pollutants, which aggravates the shortage of water resources and brings serious pollution. Among them, the wastewater discharged by the pharmaceutical industry often contains high concentrations of antibiotics. Its stable chemical properties and biological toxicity make the adsorption method and biological method in traditional wastewater treatment not ideal for removing antibiotics. Photocatalytic oxidation technology, as an environmentally friendly and low-energy sustainable wastewater treatment technology, has high catalytic oxidation activity and can efficiently degrade organic pollutants in water without selectivity. Therefore, it has good application prospects in the field of antibiotic wastewater treatment. However, there are many problems in the actual application of homogeneous photocatalysts, which affect the catalytic degradation efficiency. The photocatalytic membrane reactor fixes the photocatalyst on the membrane surface or disperses it in the membrane, transfers the catalytic reaction from the feed liquid part to the membrane area, effectively solves the problem of easy deposition and difficult recovery of the photocatalyst, and realizes the continuous reaction.

[0003] To this end, the Chinese invention patent with authorization announcement number CN106039998A discloses a photocatalytic composite nanofiltration membrane loaded with β-FeOOH nanocrystals and a preparation method thereof, wherein the photocatalytic composite nanofiltration membrane is first formed by co-deposition of dopamine and polyethyleneimine on a porous support membrane to form a cross-linked nanofiltration membrane containing a separation functional cortex, and then β-FeOOH nanocrystals are loaded on the separation functional cortex to achieve efficient treatment of dye-containing wastewater.

[0004] However, in practical applications, the catalytic membrane reactor usually has a radial flow direction perpendicular to the membrane plane, a short reaction path, and a high requirement for the reaction rate. It is only suitable for fast reaction occasions and requires multiple repeating units. Therefore, L.Aoudjit et al. reported that the TiO2 catalyst was loaded onto a poly (vinylidene fluoride-trifluoroethylene) film to construct a photocatalytic reactor, and the catalytic film was placed at the bottom of the reactor. The direction of the feed flow was parallel to the membrane surface, which fully extended the reaction time and achieved effective degradation of the organic dye tartrate (J.Hazard.Mater., 2018, 344, 408-416). However, due to the loss of light energy with the refraction of the solution, the accumulation of the upper layer of the membrane reactor affected the light penetration ability and reduced the light energy utilization rate. Therefore, the degradation rate only reached 78%. At the same time, the feed of the above-mentioned catalytic membrane reactor needs to be driven by external energy, resulting in a large amount of energy consumption. Summary of the invention

[0005] The purpose of the present invention is to provide a self-driven interfacial photocatalytic membrane reactor and a preparation method thereof. The present invention uses a hydrophilic photocatalytic membrane to cause the feed liquid in the feed box to produce a siphon effect, driving the feed liquid to flow continuously into the collection box without the need for additional energy input, and has the advantages of low energy consumption, high degradation rate, and environmental protection.

[0006] The technical solution of the present invention is as follows: a self-driven interfacial photocatalytic membrane reactor comprises a hydrophilic photocatalytic membrane loaded with a photocatalyst, a feed box and a collecting box are respectively arranged on both sides of the hydrophilic photocatalytic membrane, and the height of the feed box is higher than that of the collecting box; one end of the hydrophilic photocatalytic membrane is arranged in the feed box, and the other end of the hydrophilic photocatalytic membrane is arranged in the collecting box.

[0007] In the above-mentioned self-driven interfacial photocatalytic film reactor, the hydrophilic substrate of the hydrophilic photocatalytic film comprises hydrophilic fibers, films and fabrics.

[0008] In the aforementioned self-driven interfacial photocatalytic film reactor, the photocatalyst is a BiOX-based heterojunction photocatalyst, and X is a halogen.

[0009] In the aforementioned self-driven interfacial photocatalytic membrane reactor, the height difference between the feed box and the collection box is 3-9 cm; the horizontal distance between the feed box and the collection box is 15-21 cm.

[0010] The method for preparing the aforementioned self-driven interfacial photocatalytic film reactor comprises the following steps:

[0011] Step 1: preparing a photocatalyst film on the surface of a hydrophilic substrate to obtain a hydrophilic photocatalyst film;

[0012] Step 2: Extend one end of the hydrophilic photocatalytic membrane below the horizontal plane in the feed box, and extend the other end of the hydrophilic photocatalytic membrane into the collection box to obtain a self-driven interfacial photocatalytic membrane reactor.

[0013] The preparation method of the aforementioned self-driven interfacial photocatalytic film reactor, the process of preparing the hydrophilic photocatalyst film is as follows: taking a bismuth source, preparing nanosheets on the surface of a hydrophilic substrate by a pre-coating seed-hydrothermal synthesis method; after cleaning and drying, alternately immersing the hydrophilic substrate with the nanosheets in a silver source aqueous solution and a bromine source aqueous solution, and repeating the process multiple times; after cleaning and drying, a hydrophilic photocatalyst film is obtained.

[0014] In the preparation method of the aforementioned self-driven interfacial photocatalytic film reactor, the bismuth source is bismuth nitrate pentahydrate; the silver source is silver nitrate; and the bromine source is potassium bromide.

[0015] In the method for preparing the aforementioned self-driven interfacial photocatalytic film reactor, the nanosheets are bismuth oxybromide nanosheets.

[0016] In the method for preparing the aforementioned self-driven interfacial photocatalytic film reactor, the molar concentration of the silver source aqueous solution is 0.17-0.20M; the molar concentration of the bromine source aqueous solution is 0.12-0.15M.

[0017] In the method for preparing the aforementioned self-driven interfacial photocatalytic film reactor, the alternating immersion is repeated 5-8 times.

[0018] Compared with the prior art, the present invention prepares a photocatalyst film on the surface of a hydrophilic substrate to obtain a hydrophilic photocatalytic film. A feed box and a collecting box are connected through the hydrophilic photocatalytic film, and the height of the feed box is made higher than the collecting box, so that the feed liquid in the feed box can produce a siphon effect, and the feed liquid is driven to flow continuously through the hydrophilic photocatalytic film and flows into the collecting box; no additional energy input is required to drive the feed liquid to flow on the photocatalyst film; it has the advantages of low energy consumption, high degradation rate, and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 is a graph of siphon flow rate versus height difference between the feed box ring and the collection box;

[0021] Figure 3 is a graph of the siphon flow rate versus the horizontal distance between the feed box and the collection box.

[0022] The markings in the attached figure are: 1-feeding box, 2-collecting box, 3-hydrophilic photocatalytic membrane. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0024] Example 1: A self-driven interfacial photocatalytic film reactor, the structure of which is as follows Figure 1As shown, it includes a hydrophilic photocatalytic film 3 loaded with photocatalyst, and the hydrophilic photocatalytic film 3 is a porous structure; a feed box 1 and a collection box 2 are respectively arranged on both sides of the hydrophilic photocatalytic film 3, the feed box 1 is used to store the antibiotic wastewater to be degraded, and the collection box 2 is used to collect the water after degradation treatment; the height of the feed box 1 is higher than the collection box 2; one end of the hydrophilic photocatalytic film 3 is arranged in the feed box 1, and the other end of the hydrophilic photocatalytic film 3 is arranged in the collection box 2. The hydrophilic substrate of the hydrophilic photocatalytic film 3 can be a hydrophilic fiber, film and fabric, including a hydrophilic polyester non-woven fabric, a hydrophilic dust-free paper, a polyacrylonitrile film, a polyvinyl alcohol film, a chitin fiber or a cuprammonia fiber, etc. In this embodiment, a hydrophilic polyester non-woven fabric is used. The photocatalyst is a BiOX-based heterojunction photocatalyst, where X is a halogen, including BiOBr, BiOCl, BiOBr / g-C3N4, BiOBr / MnFe2O4, BiOBr / Fe3O4 or BiOBr / Ag / AgBr, etc. BiOBr / Ag / AgBr is used in this embodiment.

[0025] This embodiment also provides a method for preparing a self-driven interfacial photocatalytic film reactor, comprising the following steps:

[0026] Step 1: Prepare a photocatalyst film on the surface of a long strip of hydrophilic polyester non-woven fabric substrate to obtain a hydrophilic photocatalytic film. The process of preparing the photocatalyst film is as follows: take bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), and prepare bismuth oxybromide nanosheets on the surface of a hydrophilic polyester non-woven fabric substrate by a pre-coating seed-hydrothermal synthesis method; after washing and drying, alternately soak it in a silver nitrate (AgNO3) aqueous solution with a molar concentration of 0.17M and a potassium bromide (KBr) aqueous solution with a molar concentration of 0.12M, and repeat 5 times; after washing and drying, obtain a BiOBr / Ag / AgBr photocatalyst film.

[0027] Step 2: Extend one end of the hydrophilic photocatalytic membrane below the horizontal plane in the feed box, and extend the other end of the hydrophilic photocatalytic membrane into the collecting box to obtain a self-driven interfacial photocatalytic membrane reactor; there is a height difference between the feed box and the collecting box, and the feed box is higher than the collecting box, and the height difference ΔH between the feed box and the collecting box is 3 cm; the horizontal distance L between the feed box and the collecting box is 18 cm.

[0028] Example 2: The preparation method of the self-driven interfacial photocatalytic membrane reactor in this example is the same as that in Example 1, except that the height difference ΔH between the feed box and the collection box is 4.5 cm.

[0029] Example 3: The preparation method of the self-driven interfacial photocatalytic membrane reactor in this example is the same as that in Example 1, except that the height difference ΔH between the feed box and the collection box is 6 cm.

[0030] Example 4: The preparation method of the self-driven interfacial photocatalytic membrane reactor in this example is the same as that in Example 1, except that the height difference ΔH between the feed box and the collection box is 7.5 cm.

[0031] Example 5: The preparation method of the self-driven interfacial photocatalytic membrane reactor in this example is the same as that in Example 1, except that the height difference ΔH between the feed box and the collection box is 9 cm.

[0032] Example 6: The preparation method of the self-driven interfacial photocatalytic membrane reactor in this example is the same as that in Example 1, except that the horizontal distance L between the feed box and the collection box is 15 cm.

[0033] Example 7: The preparation method of the self-driven interfacial photocatalytic membrane reactor in this example is the same as that in Example 1, except that the horizontal distance L between the feed box and the collection box is 21 cm.

[0034] Furthermore, the degradation of tetracycline was tested using the interfacial photocatalytic membrane reactor prepared in Examples 1-7: a tetracycline aqueous solution with a concentration of 200 mg / L was prepared to simulate antibiotic wastewater, loaded into a feed box, and the photocatalytic membrane reactor was placed under sunlight to test the tetracycline concentration of the solution in the collection box. The results are shown in Table 1:

[0035] Table 1 Degradation efficiency of tetracycline in each embodiment

[0036] Example 1 2 3 4 5 6 7 Degradation efficiency (%) 99.9 99.8 99.5 92.7 80.3 97.5 98.2

[0037] Measure the mass of water collected in the collection box and get Figure 2 The relationship between the siphon flow rate and the height difference ΔH shown in FIG. Figure 3 The relationship between siphon flow rate and horizontal distance L is shown.

[0038] Through comparative experiments, it was found that: as the height difference ΔH between the feed box and the collection box increased, the siphon flow rate increased and the degradation efficiency decreased; as the horizontal distance L between the feed box and the collection box increased, the siphon flow rate decreased, and the degradation efficiency first increased and then decreased. Example 1 is a preferred embodiment of the present invention, and the degradation efficiency of tetracycline reached 99.9%.

[0039] In summary, the present invention prepares a photocatalyst film on the surface of a hydrophilic substrate to obtain a hydrophilic photocatalytic film, connects a feed box and a collecting box through the hydrophilic photocatalytic film, and makes the height of the feed box higher than the collecting box, so that the feed liquid in the feed box can produce a siphon effect, and the feed liquid is driven to flow continuously through the hydrophilic photocatalytic film and flows into the collecting box; no additional energy input is required to drive the feed liquid to flow on the photocatalyst film; it has the advantages of low energy consumption, high degradation rate, and environmental protection.

[0040] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. In this embodiment, the words "up", "down", "left", "right", "front" and "rear" only represent their relative positions and do not represent their absolute positions. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A self-driven interfacial photocatalytic film reactor, characterized in that: It comprises a hydrophilic photocatalytic membrane loaded with photocatalyst, wherein a feed box and a collection box are respectively arranged on both sides of the hydrophilic photocatalytic membrane, and the height of the feed box is higher than the collection box; one end of the hydrophilic photocatalytic membrane is arranged in the feed box, and the other end of the hydrophilic photocatalytic membrane is arranged in the collection box.

2. The self-driven interfacial photocatalytic film reactor according to claim 1, characterized in that: The hydrophilic substrate of the hydrophilic photocatalytic film includes hydrophilic fibers, films and fabrics.

3. The self-driven interfacial photocatalytic film reactor according to claim 1, characterized in that: The photocatalyst is a BiOX-based heterojunction photocatalyst, and X is a halogen.

4. The self-driven interfacial photocatalytic film reactor according to claim 1, characterized in that: The height difference between the feed box and the collection box is 3-9 cm; the horizontal distance between the feed box and the collection box is 15-21 cm.

5. The method for preparing the self-driven interfacial photocatalytic film reactor according to claims 1-4, characterized in that: The following steps are involved: Step 1: preparing a photocatalyst film on the surface of a hydrophilic substrate to obtain a hydrophilic photocatalyst film; Step 2: Extend one end of the hydrophilic photocatalytic membrane below the horizontal plane in the feed box, and extend the other end of the hydrophilic photocatalytic membrane into the collection box to obtain a self-driven interfacial photocatalytic membrane reactor.

6. The method for preparing the self-driven interfacial photocatalytic film reactor according to claim 5, characterized in that: The process of preparing the hydrophilic photocatalyst film is as follows: taking a bismuth source, preparing nanosheets on the surface of a hydrophilic substrate by a pre-coating seed-hydrothermal synthesis method; after cleaning and drying, alternately immersing the hydrophilic substrate with the nanosheets in a silver source aqueous solution and a bromine source aqueous solution, and repeating the process multiple times; after cleaning and drying, obtaining a hydrophilic photocatalyst film.

7. The method for preparing the self-driven interfacial photocatalytic film reactor according to claim 6, characterized in that: The bismuth source is bismuth nitrate pentahydrate; the silver source is silver nitrate; and the bromine source is potassium bromide.

8. The method for preparing the self-driven interfacial photocatalytic film reactor according to claim 7, characterized in that: The nanosheets are bismuth oxybromide nanosheets.

9. The method for preparing the self-driven interfacial photocatalytic film reactor according to claim 8, characterized in that: The molar concentration of the silver source aqueous solution is 0.17-0.20M; the molar concentration of the bromine source aqueous solution is 0.12-0.15M.

10. The method for preparing the self-driven interfacial photocatalytic film reactor according to claim 9, characterized in that: The alternating immersion is repeated 5-8 times.

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