Agricultural drainage channel barrier wall system with buckle type photocatalysis module

Abstract

The invention belongs to the technical field of agricultural non-point source pollution treatment and solid waste recycling, and particularly relates to an agricultural drainage channel barrier wall system with a buckle type photocatalysis module, which is characterized in that a plurality of barrier wall building blocks are connected and laid on the bottom and two side slopes of a drainage channel through dovetail tenon-and-mortise structures; the blocking wall has the advantages that the blocking wall with the coal gasification slag base body is combined with the replaceable photocatalytic module, so that interception, adsorption and photocatalytic degradation of pollutants in an agricultural drainage channel are realized; the problems that a traditional drainage channel blocking structure material is not continuous, the pollutant degradation capacity is insufficient, and maintenance is difficult are solved. According to the system, the adsorption-catalysis synergistic principle is adopted, and when water flows through the porous coal gasification slag-based barrier wall, adsorption-catalysis synergistic removal of pesticide residues, antibiotics and organic pollutants is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of agricultural non-point source pollution treatment and solid waste resource utilization, and particularly relates to an agricultural drainage ditch barrier wall system with a buckle type photocatalytic module. BACKGROUND

[0002] With the continuous strengthening of China's ecological environment protection policy and the gradual perfection of the water pollution prevention and control regulatory system, the sewage discharge limit value presents a step-by-step strict control trend, and the total amount control of water pollutants has achieved phased results. In the current agricultural drainage system, concrete and glass steel are the mainstream materials for the construction of drainage ditches. Among them, concrete is concerned due to the carbon emission problem in the production process of cement. According to reports, in 2020, the carbon dioxide emissions of China's cement industry were estimated at 1.379 billion tons, accounting for 12% of the country's total emissions (including process emissions). Therefore, reducing carbon emissions in the cement industry is crucial to achieving the dual-carbon goal. As a substitute material for reinforced fibers and resin matrix, glass steel has the advantages of light weight and strong corrosion resistance, but in practical application, it has significant defects such as high cost, insufficient ultraviolet resistance, and poor ecological compatibility of the hardened resin matrix, which limits its application. And with the development of agricultural intensification, the residual fertilizers, pesticides and organic pollutants in the farmland drainage ditch enter the water body through surface runoff, which has become an important source of non-point source pollution. Although the traditional agricultural drainage ditch has certain physical interception capacity, it cannot degrade soluble pollutants such as ammonia nitrogen and organic phosphorus, and long-term operation can easily cause pore blockage, without self-cleaning ability.

[0003] In recent years, photocatalytic materials (such as TiO2, g-C3N4) can undergo photocatalytic advanced oxidation reaction under ultraviolet light or sunlight, producing strong oxidizing free radicals, rapidly degrading organic pollutants adsorbed on the surface of the catalyst into CO2 and H2O, while the photocatalyst itself is not lost and does not cause secondary pollution, and has the advantages of fast reaction speed, mild reaction conditions, etc., and is therefore considered as a promising water treatment technology. For example, CN222647682U discloses a photocatalytic water purification device, which can purify water by adding an appropriate amount of alum and photocatalyst into the water body. Photocatalytic coating technology has become a research hotspot in recent years due to its unique advantages in the field of environmental pollutant degradation. For example, CN109174160A discloses a g-C3N4 photocatalytic coating and its preparation method and application, which is coated on the substrate in the form of brushing or spraying, solving the problem of wrapping photocatalyst materials in photocatalytic coatings, improving the photocatalytic performance of the coating, reducing the amount of photocatalytic materials, and reducing the cost of the coating. The feasibility of the coating technology is confirmed. CN110294510A discloses a water treatment device with a detachable photocatalytic module, the photocatalyst is a visible light catalyst, which is loaded on the surface of the rotating drum and wave plate by sintering or coating method, and the module is simple and convenient to replace. But the module based on the fixed size of the box and the guide plate design module size needs to be strictly matched with the inner wall of the box and the distance between the guide plates, which cannot be flexibly adapted to different specifications of the water treatment device. The overall replacement cost of the module is high, and the patent module integrates micro generators, LEDs and other precision components, and local faults (such as wave plate fracture) may cause the entire module to be scrapped. SUMMARY

[0004] The purpose of the present application is to provide an agricultural drainage ditch barrier wall system with a buckle type photocatalytic module, which overcomes the shortcomings of the prior art. The coal gasification slag base barrier wall and the replaceable photocatalytic module are combined to realize the interception and adsorption of pollutants in the agricultural drainage ditch and the photocatalytic degradation, achieve the adsorption-catalytic synergistic removal of pesticide residues, antibiotics and organic pollutants, and the photocatalytic module adopts a screw module structure, allowing local repair, solving the problems of unsustainable traditional drainage ditch barrier structure materials, insufficient pollutant degradation capacity and difficult maintenance.

[0005] To achieve the above purpose, the present application realizes the following technical solutions:

[0006] The utility model provides an agricultural drainage ditch barrier wall system with buckle type photocatalytic module, a plurality of barrier wall blocks are connected and laid on the bottom and the side slope of the drainage ditch in dovetail mortise structure, the photocatalytic module is connected with the barrier wall block through screw buckle, wherein: the barrier wall block is mixed by coal gasification slag, cement, fly ash, water and water glass, and is pressed and formed in a mold, and the weight ratio of each component is as follows: 55-65 parts of coal gasification slag, 20-30 parts of water, 10-15 parts of fly ash, 1-4 parts of cement and 2-3 parts of water glass; the photocatalytic module is composed of a catalyst carrier, a photocatalytic coating and a waterproof material layer, the catalyst carrier is in screw shape, and the surface of the screw head is coated with the photocatalytic coating and the waterproof material layer in sequence, and the photocatalytic coating contains g-C3N4 / BiOCl heterojunction photocatalyst.

[0007] Further, the preparation process of the barrier wall block is as follows: firstly, mix the coal gasification slag, fly ash and cement, and stir at a speed of 700-900 rpm for 1-3 min; after uniform mixing, add the formula amount of water and water glass, and stir at a speed of 700-900 rpm for 3-7 min, then press and form in a mold, the pressure of the mold pressing and forming is greater than or equal to 10 MPa, and the mold is demolded after curing for 6-8 days; the size of the barrier wall block is 40-50 cm x 50-100 cm x 10-12 cm, which can be customized for different channel widths; the edge of the barrier wall block is in dovetail mortise structure, wherein the tenon is divided into two types: the first type of tenon is in trapezoidal longitudinal section with the mortise, the root width n1 of the first type of tenon is 3-6 cm, the end width m1 of the first type of tenon is 6-12 cm, and the inner inclination angle alpha of the tenon groove of the first type of tenon is 73-81.5 degrees; the second type of tenon is in trapezoidal transverse section with the mortise, the root width n2 of the second type of tenon is 3-6 cm, the end width m2 of the second type of tenon is 6-12 cm, the inner inclination angle beta of the tenon groove of the second type of tenon is 73-81.5 degrees, and the height h of the tenon is 10-12 cm.

[0008] Further, the coal gasification slag in the barrier wall block needs to be crushed to a particle size of less than or equal to 5 mm and modified by sodium hydroxide alkaline hydrothermal modification; the modification process is as follows: the sieved and crushed coal gasification slag, sodium hydroxide and water are mixed in a weight ratio of 2-8:1-3:10-30, and are magnetically stirred at a temperature of 80-100 DEG C and a speed of 200-500 rpm for 2-4 hours, then filtered to neutral, and dried at 60-85 DEG C to obtain alkali modified coal gasification slag, the specific surface area of which is 340-362 m 2 / g, and the adsorption performance for common pesticides and antibiotics is 23-24 mg / g.

[0009] Further, the catalyst carrier is prepared by: firstly, mixing 5-7 parts of carboxyl-terminated butadiene-acrylonitrile rubber and 34-38 parts of epoxy resin to form a prepolymer by reacting at 180-200°C for 1.5-3 hours; secondly, mixing 13-17 parts of alkali-modified coal gasification slag, 7-11 parts of cement and 10-15 parts of fly ash, adding 10-15 parts of water and 3-8 parts of water glass, stirring at 700-900 rpm for 10-20 minutes, then adding all the prepolymer, stirring at 50-100 rpm for 10-20 minutes to avoid generating bubbles; finally, adding 1-2.5 parts of silane coupling agent and 0.5-1 part of dispersant, mixing and stirring at 200-400 rpm for 20-40 minutes, then placing into a mold, pressing to form, and placing into a curing box for curing until the water content is less than 1%, and the pressure of the mold pressing is greater than or equal to 10 MPa.

[0010] Further, the head of the catalyst carrier has a diameter d1 of 15-20 cm and a height of 3-8 cm, the tail has a diameter d2 of 5-10 cm and a height of 23-28 cm, the outer diameter of the thread is d3 of 5-10 cm, the effective length of the thread is 15-23 cm, the pitch is 3-8 mm, the tooth profile of the thread is 28-32° trapezoidal teeth, and the depth of screwing into the wall is 18-25 cm.

[0011] Further, the preparation method of the photocatalytic coating is as follows: mixing BiOCl and g-C3N4 in a weight ratio of 1:(2-4), mixing anhydrous ethanol as a dispersion medium with the mixture in a weight ratio of (2-7):1, magnetically stirring at 200-500 rpm for 1.5-2.5 hours, drying at room temperature for 10-14 hours after centrifugal separation, and obtaining a gray composite powder; mixing the silane coupling agent with water in a weight ratio of (3-8):(97-92) to obtain a 3-8 wt% silane coupling agent aqueous solution; mixing anhydrous ethanol with water in a weight ratio of (3-4):(2-1) to obtain a 60-80 wt% ethanol aqueous solution; mixing 15-25 parts of the composite powder with 1-3 parts of the 3-8 wt% KH-550 silane coupling agent aqueous solution, then adding 70-80 parts of the 60-80 wt% ethanol aqueous solution, and performing ultrasonic dispersion treatment at 30-60 kHz for 0.5-1.5 hours to obtain a uniform modified slurry.

[0012] Further, the coating method of the photocatalytic coating and the waterproof material layer: the modified slurry is coated on the surface of the catalyst carrier head by air spraying equipment for three times with an interval of 10-20 min each time, and the thickness of single coating is controlled to be 10-15 mu m, and dried at room temperature; finally, gradient heat treatment is carried out under nitrogen protection: the temperature is increased to 160-200 DEG C at a rate of 3-8 DEG C / min, and the temperature is kept for 0.5-1.5 h, then the temperature is continuously increased to 280-320 DEG C and kept for 25-35 min, and the furnace is cooled to room temperature, and the photocatalytic coating is formed; finally, the waterproof material layer is coated on the surface of the photocatalytic coating, the waterproof material layer is a polydimethylsiloxane hydrophobic coating, the thickness is 0.5-0.8 mu m, and the contact angle is greater than or equal to 150 DEG.

[0013] Further, the photocatalytic module is matched with a screw buckle and connected with the barrier wall block.

[0014] Further, the construction method specifically comprises the following steps: 1) assembling by bricklaying, the photocatalytic module is assembled on the barrier wall block through the screw buckle; 2) a plurality of barrier wall blocks are connected and laid on the bottom of the drainage ditch and the slope surface on both sides in a dovetail mortise structure, and the gap tolerance of the dovetail mortise structure is less than or equal to ±0.5 mm.

[0015] Further, the replacement period of the photocatalytic module is 6-12 months; the replaced photocatalytic module can be recycled after the regeneration step, the old module is first dried at 80-120 DEG C, then the photocatalytic coating and the waterproof material layer are repeatedly coated on the surface, and the old module is repeatedly used.

[0016] Compared with the prior art, the beneficial effects of the present application are:

[0017] 1) The coal gasification slag matrix barrier wall and the replaceable photocatalytic module are combined to realize the interception and adsorption of pollutants in the agricultural drainage ditch and the photocatalytic degradation, and solve the problems of unsustainable traditional drainage ditch barrier structure material, insufficient pollutant degradation capacity and difficult maintenance;

[0018] 2) The system adopts the principle of adsorption-catalysis cooperation to remove residual pollutants in the drainage ditch, when the water flows through the porous coal gasification slag matrix barrier wall, the matrix adsorbs suspended solids and heavy metals, and the photocatalytic module generates active oxygen species under light to achieve the adsorption-catalysis cooperation removal of pesticide residues, antibiotics and organic pollutants;

[0019] 3) The coal gasification slag matrix barrier wall adopts the mortise and tenon structure to facilitate combination and local replacement, the photocatalytic module with the threaded connection structure allows timely replacement when a local unit is damaged, reduces the maintenance cost, and the screw and screw buckle connection structure can be matched with an adjusting nut to adapt to barrier walls of various sizes. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 12 is a schematic diagram of the combined structure of the barrier wall block and the photocatalytic module in an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the details of the dovetail mortise and tenon structure of the barrier wall block in an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of a 90° connection of a dovetail mortise and tenon structure of a barrier wall block according to an embodiment of the present invention;

[0023] Figure 4 180° connection diagram of the dovetail mortise and tenon structure of the barrier wall blocks according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the installation of a replaceable photocatalytic module in an embodiment of the present invention;

[0025] Figure 6 is the XRD pattern of the catalyst module in an embodiment of the present invention;

[0026] Figure 7 is the catalytic performance curve of the embodiment of the present invention;

[0027] Figure 8 is a permeability coefficient curve of an embodiment of the present invention;

[0028] Figure 9 is the compressive strength curve of the embodiment of the present invention;

[0029] Figure 10 This is a diagram showing the adsorption effect of alkali-modified coal gasification slag in an embodiment of the present invention;

[0030] Figure 11 This is a diagram showing the effect of an adsorption cycle experiment on alkali-modified coal gasification slag in an embodiment of the present invention.

[0031] Explanation of the accompanying drawings: 1-tenon No. 1, 2-tenon No. 2, 3-steel nail. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the specific embodiments required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation methods of the present invention. For ordinary technicians in this field, other specific embodiments can be obtained based on these specific embodiments without paying any creative work.

[0034] The components of the embodiments of the present invention generally described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but is merely representative of selected embodiments of the present invention.

[0035] Example 1

[0036] See Figure 1-2 , is a schematic diagram of the combined structure of the barrier wall block and the photocatalytic module in an embodiment of the present invention. The coal gasification slag in the barrier wall block is crushed to a particle size of ≤4 mm and then hydrothermally modified with sodium hydroxide. The modification process is as follows: the sieved and crushed coal gasification slag is mixed with sodium hydroxide and water in a weight ratio of 2:1:10, magnetically stirred at 80°C and 200 rpm for 2 hours, then filtered to neutrality, and dried at 60°C to obtain the alkali-modified coal gasification slag with a maximum specific surface area of ​​340 m 2 / g, and the maximum adsorption performance for common pesticides and antibiotics is 23mg / g.

[0037] The barrier wall blocks are made from a mixture of coal gasification slag, cement, fly ash, water, and water glass. The weight ratio of the components is as follows: 55 parts coal gasification slag, 20 parts water, 10 parts fly ash, 1 part cement, and 2 parts water glass. First, the coal gasification slag, fly ash, and cement are mixed and stirred at 700 rpm for 1 minute. After uniform mixing, the formulated amount of water and water glass is added and stirred at 700 rpm for 3 minutes. The blocks are then pressed into shape in a mold at a pressure of 10 MPa and cured for 6 days before demolding. The barrier wall blocks can be customized to dimensions of 40 cm × 50 cm × 10 cm (height × length × thickness) to accommodate varying channel widths.

[0038] Multiple barrier wall blocks are connected by a dovetail mortise and tenon structure and laid at the bottom and both sides of the drainage channel. The dovetail mortise and tenon structure does not limit the angle of the connection part, has a wide range of applications, and can be quickly assembled and disassembled through horizontal plug-in. Figure 2 Detailed diagram of the dovetail mortise and tenon structure of a barrier wall block in an embodiment of the present invention. There are two types of dovetail mortise and tenon structures. The first tenon 1 and the mortise groove have a trapezoidal longitudinal section, the root width n1 of the first tenon is 3 cm, the end width m1 of the first tenon is 6 cm, and the inclination angle α of the tenon groove of the first tenon is 81.5°; the second tenon 2 and the mortise groove have a trapezoidal cross section, the root width n2 of the second tenon is 3 cm, the end width m2 of the second tenon is 6 cm, the inclination angle β of the tenon groove of the second tenon is 81.5°, and the tenon height h is 10 cm. Figure 3 Schematic diagram of the 90° connection of the dovetail mortise and tenon structure of the barrier wall blocks in the embodiment of the present invention, using the No. 1 tenon 1 and the No. 2 tenon 2 to install the bottom and side barrier wall blocks at 90°, such as Figure 4The 180-degree connection schematic diagram of the blocking wall block dovetail mortise and tenon structure in the embodiment of the application adopts a No. 1 tenon to install the side blocking wall block in 180 degrees, can adopt a steel nail 3 to assist in fixing, and coats epoxy resin at the mortise and tenon connection position. In actual application, the wall body has higher scouring resistance than a traditional concrete structure, the material cost is reduced by 10%, and is suitable for ecological slope protection engineering of a high flow rate agricultural drainage ditch.

[0039] Catalyst carrier preparation: first, 5 parts of carboxyl-terminated nitrile rubber and 34 parts of epoxy resin are premixed to form a prepolymer by reacting at 180℃ for 1.5 hours; 13 parts of alkali-modified coal gasification slag, 7 parts of cement and 10 parts of fly ash are mixed, 10 parts of water and 3 parts of water glass are added, 700 rpm stirring for 10 minutes, then all the prepolymer is added, 50 rpm stirring for 10 minutes to avoid air bubbles; finally, 1 part of silane coupling agent and 0.5 part of dispersant are added, 200 rpm mixing and stirring for 20 minutes, then put into a mold, press into shape, and put into a curing box to cure until the water content is <0.6%. In the embodiment, the head diameter d1 of the catalyst carrier is 15 cm, the height is 3 cm, the tail diameter d2 is 5 cm, the height is 23 cm, the outer diameter of the thread d3 is 5 cm, the effective length of the thread is 15 cm, the pitch is 3 mm, the thread type is 28° trapezoidal tooth, and the screwing depth into the wall body is 18 cm.

[0040] Preparation method of the photocatalytic coating: BiOCl and g-C3N4 are mixed in a weight ratio of 1:2, anhydrous ethanol is used as a dispersion medium and mixed with the mixture in a weight ratio of 2:1, 200 rpm magnetic stirring for 1.5 h, centrifugal separation, and drying at room temperature for 10 h to obtain a gray composite powder; the silane coupling agent and water are mixed in a weight ratio of 3:97 to obtain a 3wt% silane coupling agent aqueous solution; anhydrous ethanol and water are mixed in a weight ratio of 3:2 to obtain a 60wt% ethanol aqueous solution; 15 parts of the composite powder are mixed with 1 part of the 3wt% KH-550 silane coupling agent aqueous solution, and then 70 parts of the 60wt% ethanol aqueous solution are added, and 30 kHz ultrasonic dispersion treatment is performed for 0.5 h to obtain a uniform modified slurry.

[0041] Coating method of the photocatalytic coating and the waterproof material layer: the modified slurry is coated on the head surface of the catalyst carrier by air spraying equipment in three times, each time interval is 10 min, the single coating thickness is controlled to be 10 μm, and room temperature drying is performed; finally, gradient heat treatment is performed under nitrogen protection: the temperature is increased to 160℃ at a rate of 3℃ / min, the temperature is kept for 0.5 h, the temperature is continuously increased to 280℃, the temperature is kept for 25 min, the furnace is cooled to room temperature, and the photocatalytic coating is formed; finally, the waterproof material layer is coated on the surface of the photocatalytic coating, the waterproof material layer is a polydimethylsiloxane hydrophobic coating layer, the thickness is 0.5 μm, and the contact angle is ≥150°.

[0042] As Figure 5The replaceable photocatalytic module installation schematic diagram in the embodiment of the application, the photocatalytic module is connected with the barrier wall block through the screw buckle form, the barrier wall block is provided with a threaded hole with a corresponding size, and the screw-shaped photocatalytic module is embedded in the barrier wall block by rotating to a depth. The modules are installed at intervals of 20 cm along the drainage direction and can catalytically degrade pollutants under natural light. After being disassembled and washed every quarter, the modules can be reused, and the operation and maintenance efficiency is improved compared with the traditional fixed reactor. When the water quality sampling and detection by artificial personnel every month shows that COD and the like exceeds the standard, the invalid catalyst coating can be replaced, and the photocatalytic module can continue to be used.

[0043] The construction method of the barrier wall system specifically includes the following steps: 1) masonry assembly, the photocatalytic module is assembled to the barrier wall block through the screw buckle; 2) a plurality of barrier wall blocks are connected and laid on the bottom of the drainage channel and the slope surfaces on both sides in a dovetail mortise structure, and the gap tolerance of the dovetail mortise structure is ≤±0.5 mm.

[0044] The replacement cycle of the photocatalytic module is 6 months; the photocatalytic module replaced can be recycled after a regeneration step, the old module is first dried at 80 ℃, and then the photocatalytic coating and the waterproof material layer are repeatedly coated on the surface, and the photocatalytic module is repeatedly used.

[0045] Embodiment 2

[0046] In the barrier wall block, the coal gasification slag is crushed to a particle size ≤5 mm and is subjected to hydrothermal modification by sodium hydroxide; the modification process is as follows: the sieved and crushed coal gasification slag, sodium hydroxide and water are mixed at a weight ratio of 5:2:20, and are subjected to magnetic stirring at 90 ℃ and a rotation speed of 300 rpm for 3 hours, and then are filtered to neutral, and are dried at 80 ℃ to obtain the alkali-modified coal gasification slag. Figure 10-11 The adsorption capacity of the common pesticides and antibiotics is 23 mg / g at most, and the adsorption equilibrium can be reached in 100 min; the removal rate of different pollutants is more than 95%; after 5 cycles of experiments, the removal rate is still more than 86%, which proves that the adsorption effect of the material is good.

[0047] The barrier wall block is mixed by the coal gasification slag, cement, fly ash, water and water glass, and the weight ratio of the components is as follows: 60 parts of the coal gasification slag, 25 parts of water, 12 parts of fly ash, 1.5 parts of cement and 2.5 parts of water glass; first, the coal gasification slag, fly ash and cement are mixed and stirred at 800 rpm for 2 min. After being uniformly mixed, the water and water glass in the formula amount are added, and stirring is performed at 800 rpm for 5 min, and then the mixture is pressed into a mold, the pressure of the mold pressing is 20 MPa, and the mold is demolded after being cured for 7 days. The size of the barrier wall block can be customized as 45 cm×80 cm×10 cm (height×length×thickness).

[0048] The multi-block barrier wall blocks are laid on the bottom and two sides of the drainage ditch through dovetail mortise structures, the dovetail mortise structures do not limit the angle of the connected parts, are widely applicable, and are fast assembled and disassembled through horizontal insertion. Figure 3 In the embodiment of the application, the barrier wall block dovetail mortise structure 90-degree connection schematic diagram is shown in Figure 1, the one-end dovetail 1 and the two-end dovetail 2 are used for 90-degree installation of the bottom and side barrier wall blocks, and the one-end dovetail 1 is used for 180-degree installation of the side barrier wall blocks. Figure 4 In the embodiment of the application, the barrier wall block dovetail mortise structure 90-degree connection schematic diagram is shown in Figure 1, the one-end dovetail 1 and the two-end dovetail 2 are used for 90-degree installation of the bottom and side barrier wall blocks, and the one-end dovetail 1 is used for 180-degree installation of the side barrier wall blocks.

[0049] The photocatalytic module is composed of a catalyst carrier, a photocatalytic coating and a waterproof material layer.

[0050] The preparation method of the photocatalytic coating is as follows: BiOCl and g-C3N4 are mixed at a weight ratio of 1:3, anhydrous ethanol is used as a dispersion medium and mixed with the mixture at a weight ratio of 5:1, 300 rpm magnetic stirring is performed for 2 h, centrifugal separation is performed, and then the mixture is dried at room temperature for 12 h to obtain a gray composite powder, Figure 6The XRD pattern of the catalyst module in the embodiment of the present application appears corresponding catalyst characteristic peaks, proving that the catalyst synthesis is successful, and the catalyst can photocatalyze common organic pollutants such as antibiotics and pesticides in agricultural planting under natural light. A silane coupling agent and water are mixed in a weight ratio of 1:19 to obtain a 5wt% silane coupling agent aqueous solution; anhydrous ethanol and water are mixed in a weight ratio of 7:3 to obtain a 70wt% ethanol aqueous solution; 20 parts of the composite powder are mixed with 2 parts of a 95wt% KH-550 silane coupling agent aqueous solution, and then 78 parts of the 70wt% ethanol aqueous solution is added, and ultrasonic dispersion treatment is performed at 40 kHz for 1 h to obtain a uniform modified slurry.

[0051] The coating method of the photocatalytic module: the modified slurry is coated on the surface of the catalyst carrier by air spraying equipment for three times, each time interval is 15 min, the single coating thickness is controlled at 12 μm, and drying is performed at room temperature; finally, gradient heat treatment is performed under nitrogen protection: the temperature is increased to 180℃ at a rate of 5℃ / min, and the temperature is kept for 1 h, then the temperature is continuously increased to 300℃ and kept for 30 min, and the furnace is cooled to room temperature, to form a photocatalytic coating; finally, a waterproof material layer is coated on the surface of the photocatalytic coating, the waterproof material layer is a polydimethylsiloxane hydrophobic coating layer, the thickness is 0.65 μm, and the contact angle is ≥160°.

[0052] The barrier wall block is provided with a threaded hole with a corresponding size, and the screw-shaped photocatalytic module is embedded in the barrier wall block to a depth by rotating. The modules are installed at intervals of 25 cm along the drainage direction, and can catalyze and degrade pollutants under natural light. Tests show that the degradation rate of the modules to common pesticides and antibiotics reaches 94%, and the modules can be reused after being disassembled and washed every quarter, which improves the operation and maintenance efficiency compared with traditional fixed reactors.

[0053] The construction method of the barrier wall system specifically includes the following steps: 1) block assembly, the photocatalytic modules are assembled to the barrier wall blocks by screw buckles; 2) a plurality of barrier wall blocks are connected and laid on the bottom of the drainage ditch and the slope surfaces on both sides in a dovetail mortise structure, and the gap tolerance of the dovetail mortise structure is ≤±0.5 mm.

[0054] The replacement cycle of the photocatalytic module is 8 months; the replaced photocatalytic module can be recycled after the regeneration step, the old module is first dried at 100℃, and then the photocatalytic coating and the waterproof material layer are repeatedly coated on the surface for repeated use.

[0055] Embodiment 3

[0056] The coal gasification slag in the barrier wall block needs to be crushed to a particle size of ≤5 mm and modified by sodium hydroxide alkaline hydrothermal modification; the modification process is as follows: the sieved and crushed coal gasification slag, sodium hydroxide and water are mixed in a weight ratio of 8:3:30, and are magnetically stirred at a temperature of 100℃ and a rotating speed of 500 rpm for 4 hours, and then filtered to neutral, and dried at 85℃ to obtain the alkali-modified coal gasification slag, and the maximum specific surface area is 362 m2 / g, and the adsorption capacity for common pesticides and antibiotics is 24 mg / g at most.

[0057] The barrier wall block is mixed by coal gasification slag, cement, fly ash, water and water glass, and the weight ratio of each component is: coal gasification slag 65 parts, water 30 parts, fly ash 15 parts, cement 4 parts, and water glass 3 parts. First, the coal gasification slag, fly ash and cement are mixed and stirred at 900 rpm for 3 min. After uniform mixing, the formula amount of water and water glass is added, and stirred at 900 rpm for 7 min. The mold is pressed and formed, the pressure of the mold pressing and forming is 30 MPa, and the mold is demolded after 8 days of curing. Figure 8 is the change of the permeability coefficient of the barrier material under the condition of different freeze-thaw cycle numbers in the embodiment of the present application. Freeze-thaw experiment is an important engineering technology, which can help manufacturers and scientists to effectively evaluate the performance of the material, so as to effectively ensure the reliability of the design. Figure 8 The permeability coefficient gradually increases with the increase of the freeze-thaw cycle number, and when the freeze-thaw cycle number increases from the first time to the fifth time, the permeability coefficient changes little and still reaches 7.4*10 -7 cm / s, and the permeability coefficient changes sharply from the sixth time. According to the standard of “Polluted Land Risk Control Technology Guide-Barrier Technology (Trial)”, the permeability coefficient should meet the requirement of 1*10 -6 cm / s below, and the present application meets the standard requirement. Figure 9 is the change rule of the compressive strength of the barrier wall under the condition of different freeze-thaw cycle numbers in the embodiment of the present application. With the increase of the freeze-thaw cycle number, the compressive strength gradually decreases. At the beginning of the freeze-thaw cycle, the initial compressive strength is 1.83 MP, and after the sixth freeze-thaw cycle, the compressive strength sharply decreases, and the compressive strength still reaches about 1.33 MP.

[0058] The size of the barrier wall block can be customized as 50 cm*100 cm*10 cm (height*length*thickness), which is suitable for different channel widths. The tenon of the dovetail mortise structure has two types. The first tenon 1 has a trapezoidal longitudinal section with the mortise, the root width n1 of the first tenon is 6 cm, the end width m1 of the first tenon is 12 cm, and the inner inclination angle a of the tenon groove of the first tenon is 73°. The second tenon 2 has a trapezoidal transverse section with the mortise, the root width n2 of the second tenon is 6 cm, the end width m2 of the second tenon is 12 cm, the inner inclination angle β of the tenon groove of the second tenon is 73°, and the height h of the tenon is 10 cm. Figure 3 The 90° connection schematic diagram of the barrier wall block dovetail mortise structure in the embodiment of the present application is shown in FIG. 1, which adopts the first tenon 1 and the second tenon 2 to install the bottom and side barrier wall blocks at 90°. Figure 4 The 180° connection schematic diagram of the barrier wall block dovetail mortise structure in the embodiment of the present application is shown in FIG. 2, which adopts the first tenon 1 to install the side barrier wall block at 180°.

[0059] Catalyst carrier preparation: first, mix 7 parts of carboxyl-terminated nitrile rubber and 38 parts of epoxy resin to form a prepolymer by reacting at 200°C for 3 hours; mix 17 parts of alkali-modified coal gasification slag, 11 parts of cement and 15 parts of fly ash, add 15 parts of water and 8 parts of water glass, stir at 900 rpm for 20 minutes, then add all the prepolymer, stir at 100 rpm for 20 minutes to avoid air bubbles; finally, add 2.5 parts of silane coupling agent and 1 part of dispersant, mix and stir at 400 rpm for 40 minutes, then put into a mold, press into shape, and put into a curing box for curing until the water content is <1%. In the example, the head diameter d1 of the catalyst carrier is 20 cm, the height is 8 cm, the tail diameter d2 is 10 cm, the height is 28 cm, the thread outer diameter d3 is 10 cm, the thread effective length is 23 cm, the thread pitch is 8 mm, the thread type is 32° trapezoidal tooth, and the screw depth into the wall is 25 cm. The surface of the photocatalytic module is provided with a cross-shaped groove, which can be easily removed by counterclockwise rotation for periodic regeneration or upgrading of the photocatalytic coating.

[0060] Preparation method of photocatalytic coating: mix BiOCl and g-C3N4 at a weight ratio of 1:4, use anhydrous ethanol as a dispersion medium, mix the mixture with anhydrous ethanol at a weight ratio of 7:1, magnetically stir at 500 rpm for 2.5 hours, centrifuge and dry at room temperature for 14 hours to obtain a gray composite powder; mix the silane coupling agent with water at a weight ratio of 2:23 to obtain an 8wt% silane coupling agent aqueous solution; mix anhydrous ethanol with water at a weight ratio of 4:1 to obtain an 80wt% ethanol aqueous solution; mix 25 parts of the composite powder with 3 parts of the 8wt% KH-550 silane coupling agent aqueous solution, then add 80 parts of the 80wt% ethanol aqueous solution, and perform ultrasonic dispersion treatment at 60 kHz for 1.5 hours to obtain a uniform modified slurry.

[0061] Coating method of photocatalytic coating and waterproof material layer: the modified slurry is coated on the surface of the head of the catalyst carrier by air spraying equipment in three times, each time interval is 20 minutes, the single coating thickness is controlled at 15μm, and the room temperature is dried; finally, gradient heat treatment is performed under nitrogen protection: the temperature is increased to 200°C at a rate of 8°C / min, kept for 1.5 hours, the temperature is continuously increased to 320°C, kept for 35 minutes, and the furnace is cooled to room temperature, to form the photocatalytic coating; finally, a waterproof material layer is coated on the surface of the photocatalytic coating, the waterproof material layer is a polydimethylsiloxane hydrophobic coating with a thickness of 0.8μm and a contact angle ≥150°.

[0062] The photocatalytic module is connected with the barrier wall block by screw clamping, the barrier wall block is provided with a threaded hole with a corresponding size, and the screw-shaped photocatalytic module is embedded into the barrier wall block by rotating. The modules are installed at an interval of 25 cm along the drainage direction, and can catalytically degrade pollutants under natural light. After being disassembled and washed every quarter, the modules can be reused, which improves the operation and maintenance efficiency compared with the traditional fixed reactor. Figure 7The catalytic performance curve in the embodiment of the present application can be seen, and the adsorption removal rate of the four pollutants can reach about 25% under no light condition, and the removal rate is more than 95% after 3 hours of light, and the catalytic performance is good.

[0063] The construction method of the barrier wall system specifically comprises the following steps: 1) masonry assembly, assembling the photocatalytic module to the barrier wall block through screw buckle; 2) laying multiple barrier wall blocks in dovetail mortise structure on the bottom and both sides of the drainage ditch, and the gap tolerance of the dovetail mortise structure is ≤±0.5mm.

[0064] The replacement period of the photocatalytic module is 12 months; the replaced photocatalytic module can be recycled after the regeneration step, and the old module is first dried at 120℃, and then repeatedly used after repeatedly coating the photocatalytic coating and the waterproof material layer on the surface.

[0065] Although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An agricultural drainage ditch barrier wall system with a snap-on photocatalytic module, characterized in that: Multiple barrier wall blocks are connected with dovetail mortise and tenon joints and laid on the bottom and slopes of the drainage channel. The photocatalytic modules are connected to the barrier wall blocks with screws and buckles, where: The barrier wall blocks are made by mixing coal gasification slag, cement, fly ash, water and water glass, and pressing them in a mold. The weight ratio of the components is as follows: 55-65 parts of coal gasification slag, 20-30 parts of water, 10-15 parts of fly ash, 1-4 parts of cement, and 2-3 parts of water glass. The photocatalytic module consists of a catalyst carrier, a photocatalytic coating and a waterproof material layer. The catalyst carrier is a screw-shaped structure, and the surface of the screw head is coated with a photocatalytic coating and a waterproof material layer in sequence. The photocatalytic coating contains a g-C3N4 / BiOCl heterojunction photocatalyst.

2. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 1, characterized in that: The preparation process of the barrier wall block is as follows: first, coal gasification slag, fly ash and cement are mixed, and stirred at a speed of 700-900 rpm for 1-3 minutes; after mixing evenly, water and water glass in the formula amount are added, and stirred at 700-900 rpm for 3-7 minutes, and pressed into shape in a mold. The pressure of the mold pressing is ≥10MPa, and the block is demoulded after curing for 6-8 days. The size of the barrier wall block is 40-50cm in height × 50-100cm in length × 10-12cm in thickness, which can be customized to suit different channel widths; The edge of the partition wall block is a dovetail mortise and tenon structure, in which there are two types of tenons: the No. 1 tenon and the mortise have a trapezoidal longitudinal section, the root width n1 of the No. 1 tenon is 3-6cm, the end width m1 of the No. 1 tenon is 6-12cm, and the inclination angle α of the tenon groove of the No. 1 tenon is 73°-81.5°; the No. 2 tenon and the mortise have a trapezoidal cross-section, the root width n2 of the No. 2 tenon is 3-6cmcm, the end width m2 of the No. 2 tenon is 6-12cm, the inclination angle β of the tenon groove of the No. 2 tenon is 73°-81.5°, and the tenon height h is 10-12cm.

3. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 2, characterized in that: The coal gasification slag in the barrier wall blocks needs to be crushed to a particle size of ≤5mm and then subjected to sodium hydroxide hydrothermal modification. The modification process is as follows: the sieved and crushed coal gasification slag is mixed with sodium hydroxide and water in a weight ratio of 2-8:1-3:10-30 parts, magnetically stirred at a temperature of 80-100°C and a rotation speed of 200-500rpm for 2-4 hours, then filtered to neutrality, and dried at 60-85°C to obtain alkali-modified coal gasification slag with a specific surface area of ​​340-362m 2 / g, and its adsorption performance for common pesticides and antibiotics is 23-24mg / g.

4. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 1, characterized in that: The catalyst carrier is prepared by premixing 5-7 parts of carboxyl-terminated nitrile rubber and 34-38 parts of epoxy resin, reacting at 180-200°C for 1.5-3 hours to form a prepolymer; mixing 13-17 parts of alkali-modified coal gasification slag, 7-11 parts of cement and 10-15 parts of fly ash, adding 10-15 parts of water and 3-8 parts of water glass, stirring at 700-900 rpm for 10-20 minutes, adding all the prepolymer, and stirring at 50-100 rpm for 10-20 minutes to avoid generating bubbles; finally, adding 1-2.5 parts of silane coupling agent and 0.5-1 part of dispersant, mixing and stirring at 200-400 rpm for 20-40 minutes, placing in a mold, pressing and molding, and placing in a curing box for curing until the moisture content is less than 1% and the mold pressing pressure is ≥10 MPa.

5. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 1, characterized in that: The catalyst carrier has a head diameter d1 of 15-20 cm and a height of 3-8 cm, a tail diameter d2 of 5-10 cm and a height of 23-28 cm, a thread outer diameter d3 of 5-10 cm, an effective thread length of 15-23 cm, a pitch of 3-8 mm, a thread profile of 28-32° trapezoidal teeth, and a depth of screwing into the wall of 18-25 cm.

6. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 1, characterized in that: The preparation method of the photocatalytic coating comprises the following steps: mixing BiOCl and g-C3N4 in a weight ratio of 1:(2-4), mixing anhydrous ethanol as a dispersion medium with the mixture in a weight ratio of (2-7):1, magnetically stirring at 200-500 rpm for 1.5-2.5 hours, centrifuging, and drying at room temperature for 10-14 hours to obtain a gray composite powder; mixing a silane coupling agent and water in a weight ratio of (3-8):(97-92) to obtain a 3-8 wt% silane coupling agent aqueous solution; and mixing anhydrous ethanol and water in a weight ratio of (3-4):(2-1) to obtain a 60-80 wt% ethanol aqueous solution. Mix 15-25 parts of composite powder with 1-3 parts of 3-8wt% KH-550 silane coupling agent aqueous solution, then add 70-80 parts of 60-80wt% ethanol aqueous solution, and perform ultrasonic dispersion treatment at 30-60kHz for 0.5-1.5h to obtain a uniform modified slurry.

7. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 1, characterized in that: The coating method of the photocatalytic coating and the waterproof material layer comprises the following steps: coating the modified slurry on the surface of the catalyst carrier head three times through air spraying equipment, with each coating interval of 10-20 minutes, controlling the thickness of a single coating to be 10-15 μm, and drying at room temperature; finally, performing a gradient heat treatment under nitrogen protection: heating to 160-200° C. at a rate of 3-8° C. / min, maintaining the temperature for 0.5-1.5 hours, continuing to heat to 280-320° C., maintaining the temperature for 25-35 minutes, and cooling to room temperature with the furnace to form a photocatalytic coating; finally, coating the surface of the photocatalytic coating with a waterproof material layer, wherein the waterproof material layer is a polydimethylsiloxane hydrophobic coating with a thickness of 0.5-0.8 μm and a contact angle of ≥150°.

8. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to claim 1, characterized in that: The photocatalytic module is used in conjunction with screw clips and is connected to the barrier wall blocks.

9. The agricultural drainage channel barrier wall system with a snap-on photocatalytic module according to any one of claims 1 to 8, characterized in that: The construction method specifically includes the following steps: 1) Masonry assembly: assemble the photocatalytic module onto the barrier wall blocks using screws and buckles; 2) Multiple barrier wall blocks are connected with dovetail mortise and tenon structures and laid on the bottom and slopes on both sides of the drainage channel. The clearance fit tolerance of the dovetail mortise and tenon is ≤±0.5mm.

10. The agricultural drainage channel barrier wall system with snap-on photocatalytic modules according to claim 9, characterized in that: The replacement cycle of the photocatalytic module is 6-12 months; the replaced photocatalytic module can be recycled after regeneration step, the old module is first placed at 80-120 ° C for drying, and then repeatedly coated with photocatalytic coating and waterproof material layer before reuse.

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