A photocatalytic suspension material for black and smelly river bodies, preparation method and application thereof

Abstract

The present invention belongs to the field of photocatalysis technology and discloses a photocatalytic suspension material for use in black and odorous river bodies, a preparation method, and its application. The material comprises a substrate and a catalyst layer. The substrate is a lightweight brick, and the catalyst layer is formed by coating the lightweight brick surface with a metal salt via a sol-gel method. The present invention uses lightweight bricks as the substrate. Lightweight bricks have the advantages of low density and high buoyancy, allowing them to be stably suspended on the water surface. The catalyst is attached to the microporous structure of the lightweight bricks in the form of a gel via the sol-gel method, preventing the catalyst from being lost with water and increasing the contact area with light, thereby enhancing the photocatalytic effect and effectively degrading sodium dodecylbenzenesulfonate, COD, and NH3-N in black and odorous river bodies.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalysis technology, and in particular relates to a photocatalytic suspension material for black and smelly river bodies, a preparation method and an application thereof. Background Art

[0002] Black and odorous water bodies not only seriously affect the water's aesthetics but also pose a significant threat to the ecological environment and human health. Ammonia nitrogen is a common pollutant in black and odorous water bodies. High concentrations of ammonia nitrogen deplete dissolved oxygen in the water, leading to hypoxia, suffocating aquatic organisms such as fish and disrupting the balance of the aquatic ecosystem. Chemical oxygen demand (COD) reflects the degree of contamination by reducing substances in the water. A high COD in black and odorous water indicates the presence of a large amount of organic matter. These organic substances also consume large amounts of dissolved oxygen during decomposition, exacerbating hypoxia and providing nutrients for the growth of harmful microorganisms, further deteriorating water quality. Sodium dodecylbenzenesulfonate, a common anionic surfactant widely used in detergents, industrial cleaning agents, and other products, is a common organic pollutant in black and odorous water bodies. It reduces the surface tension of water, hindering the dissolution and transport of oxygen in water, further exacerbating hypoxia. It is difficult to degrade naturally and accumulates in the water, causing toxic effects on aquatic organisms, affecting their growth, reproduction, and physiological functions.

[0003] Faced with the serious harm posed by these pollutants in black and odorous water, traditional water treatment technologies have exposed numerous shortcomings. Physical treatment methods such as sedimentation and filtration can only partially remove suspended particulate matter and have limited effectiveness against pollutants such as ammonia nitrogen, dissolved organic matter, and sodium dodecylbenzene sulfonate. Chemical treatment methods, while able to degrade pollutants to a certain extent, often introduce new chemicals, causing secondary pollution. Biological treatment methods have stringent requirements for environmental conditions such as water quality and temperature, and their treatment efficiency is relatively low, making them difficult to meet the demand for rapid treatment of black and odorous water.

[0004] Although the current photocatalytic technology for treating black and odorous water bodies has been applied, it also has many shortcomings. The fixation and recovery of photocatalysts are relatively difficult. If directly added to the water body, the catalyst is easily lost with the water, resulting in waste of resources and potential secondary pollution; if immobilization technology is used, the activity of the catalyst may be affected due to improper fixation. Titanium dioxide is a commonly used photocatalyst. It is currently generally added directly to the water body in powder form, or loaded on a carrier in powder form. Both methods can easily cause the catalyst to be lost with the water. In order to overcome the shortcomings of existing technologies, it is urgent to find an efficient and environmentally friendly method for treating black and odorous water bodies. Summary of the Invention

[0005] In order to address the shortcomings of the existing technology, the purpose of the present invention is to provide a photocatalytic suspension material, preparation method and application for black and smelly river bodies. Through the sol-gel method, the lightweight bricks are made to have photocatalytic activity and can be suspended on the water surface, effectively degrading organic pollutants in the water and improving water quality.

[0006] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0007] A photocatalytic suspension material for black and smelly river bodies comprises a substrate and a catalyst layer. The substrate is a lightweight brick and the catalyst layer is obtained by coating a metal salt on the surface of the lightweight brick through a sol-gel method.

[0008] Preferably, the density of the aforementioned lightweight brick is 0.5~1.0 g / cm³.

[0009] Preferably, the aforementioned metal salt is titanium alkoxide Ti(OC3H7)4.

[0010] Preferably, the thickness of the catalyst layer is 5-20 μm.

[0011] The method for preparing the above-mentioned photocatalytic suspension material for black and smelly river bodies comprises the following steps:

[0012] S1. Add titanium alkoxide Ti(OC3H7)4 and lightweight bricks into an organic solvent, stir thoroughly, then add water and organic acid to form a sol that combines with the lightweight bricks to obtain titanium dioxide modified lightweight bricks (DC-Ti);

[0013] S2, aging the DC-Ti at room temperature for a period of time to allow the particles to slowly polymerize to form a gel;

[0014] S3. Drying the aged DC-Ti and calcining it to obtain a photocatalytic suspension material.

[0015] Preferably, the organic solvent is one of propanol, ethanol or isopropanol, and the organic acid is glacial acetic acid or citric acid.

[0016] Preferably, the mass ratios of the titanium alkoxide, lightweight brick, organic solvent, water and organic acid are 1:5~10:2~5:0.5~2:0.1~0.5 respectively.

[0017] Application of photocatalytic suspended materials in the degradation of sodium dodecylbenzenesulfonate, COD and ammonia nitrogen in black and smelly river bodies.

[0018] Preferably, the pH of the aforementioned black and smelly river body is 5-7.

[0019] The benefits of the present invention are as follows: the present invention adopts lightweight bricks as a substrate. Lightweight bricks have the advantages of low density and high buoyancy, and can be stably suspended on the water surface. The catalyst is attached to the microporous structure of the lightweight bricks in the form of gel through the sol-gel method, which can prevent the catalyst from being lost with water, and can increase the contact area of ​​light, improve its photocatalytic effect, and effectively degrade sodium dodecylbenzenesulfonate, COD and NH3-N in black and smelly river bodies; the present invention has low cost, is easy to produce and apply on a large scale, is environmentally friendly, and does not produce secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing the degradation effect of catalytic materials on SDBS in black and odorous water bodies;

[0021] Figure 2 This is a diagram showing the degradation effect of catalytic materials on COD in black and odorous water bodies;

[0022] Figure 3 This is a diagram showing the degradation effect of catalytic materials on ammonia nitrogen in black and odorous water bodies;

[0023] Figure 4 This is a graph showing the degradation effects of photocatalytic suspended materials at different pH values;

[0024] Figure 5 This is a diagram showing the degradation effect of photocatalytic suspended materials under natural light. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1: A method for preparing a photocatalytic suspension material for black and smelly river bodies, comprising the following steps:

[0027] S1. Add 28.42 g of titanium alkoxide Ti(OC3H7)4 (0.1 mol) and 142.1 g of lightweight bricks to 56.84 g of propanol, stir thoroughly, then add 14.21 g of water and 2.84 g of glacial acetic acid. Stir on a thermostatic stirrer at 40 °C for 3 h to hydrolyze and condense Ti(OC3H7)4 to form a sol that combines with the lightweight brick to obtain titanium dioxide modified lightweight bricks (DC-Ti).

[0028] S2, aging DC-Ti at room temperature for 24 h to allow the particles to slowly polymerize and form a gel;

[0029] S3. The aged DC-Ti was placed in a drying oven at 80°C for 3 h, and then placed in a muffle furnace and calcined at 400°C for 4 h to obtain a photocatalytic suspension material.

[0030] Example 2: A method for preparing a photocatalytic suspension material for black and smelly river bodies, comprising the following steps:

[0031] S1. Add 56.84 g of titanium alkoxide Ti(OC3H7)4 (0.2 mol) and 568.4 g of lightweight bricks to 284.2 g of ethanol, stir thoroughly, then add 113.68 g of water and 28.42 g of glacial acetic acid. Stir on a thermostatic stirrer at 50 °C for 2 h to hydrolyze and condense Ti(OC3H7)4 to form a sol that combines with the lightweight brick to obtain titanium dioxide modified lightweight bricks (DC-Ti).

[0032] S2, aging DC-Ti at room temperature for 24 h to allow the particles to slowly polymerize and form a gel;

[0033] S3. The aged DC-Ti was placed in a drying oven at 70°C for 3 h, and then placed in a muffle furnace and calcined at 500°C for 4 h to obtain a photocatalytic suspension material.

[0034] Comparative Example 1: The difference between this comparative example and Example 1 is that the catalyst is in powder form and directly attached to the lightweight brick. The specific preparation process is as follows:

[0035] 7.98 g of titanium dioxide powder (0.1 mol) and 142.1 g of lightweight bricks were added to propanol and stirred thoroughly for 1 hour to evenly disperse the titanium dioxide powder and adhere to the surface of the lightweight bricks. The mixed material was placed in a drying oven and dried at 80°C for 3 hours to remove the propanol solvent. The dried material was then calcined at 400°C for 4 hours in a muffle furnace to strengthen the bond between the titanium dioxide and the lightweight bricks, resulting in a photocatalytic material.

[0036] Comparative Example 2: The difference between this comparative example and Example 1 is that the titanium alkoxide is directly used to obtain the photocatalytic material through the sol-gel method without being combined with the lightweight brick.

[0037] Comparative Example 3: 7.98 g of commercially available titanium dioxide powder (0.1 mol) was selected.

[0038] Performance testing

[0039] (1) Degradation effect of photocatalytic suspended materials

[0040] Four sets of experiments were designed to test the catalytic effects of the catalytic materials in Example 1, Example 2, and Comparative Examples 1-3. A 2-liter sample of black and odorous water from a river was placed in a reaction vessel. The initial concentrations of SDBS, COD, and ammonia nitrogen in the black and odorous water were 124 mg / L, 298 mg / L, and 51 mg / L, respectively, and the pH was 6. The catalytic material was added and uniformly suspended using a magnetic stirrer at 300 rpm. A 300 W high-pressure mercury lamp (dominant wavelength, 365 nm) was used as the light source, positioned 20 cm from the liquid surface. A quartz cold trap was installed externally to prevent the reaction solution from overheating. The reaction solution temperature was controlled at 25±2°C. The light source was turned on and a timer was kept running. 10 mL of samples were taken every 0.5 h, filtered through a 0.45 μm filter membrane, and the concentrations of sodium dodecylbenzenesulfonate (SDBS), COD, and ammonia nitrogen were determined. SDBS concentration was determined by high-performance liquid chromatography (HPLC) using a mobile phase of methanol / water (70:30) at a detection wavelength of 224 nm. COD concentration was determined using the potassium dichromate method (GB 11914-89). Ammonia nitrogen concentration was determined using Nessler's reagent spectrophotometry (HJ 535-2009) at a detection wavelength of 420 nm. By recording and analyzing pollutant concentrations at different time points, calculating degradation rates and plotting degradation curves, the performance differences of different catalysts were compared. Specific results are shown in [ 1 ]. Figures 1-3 .

[0041] Depend on Figures 1-3 It can be seen that the pollutant degradation rates in Comparative Examples 1-3 are significantly lower than those in Examples 1 and 2. This is because the TiO2 in Comparative Example 1 easily falls off, reducing active sites and resulting in a lower degradation rate. In Comparative Example 2, because lightweight bricks were not used, the TiO2 sol-gel material easily settles and cannot be suspended on the water surface, resulting in low light utilization. The pure TiO2 powder used in Comparative Example 3 suffers from severe agglomeration and insufficient effective reaction area. Therefore, the photocatalytic suspension materials in Examples 1 and 2 have significant advantages in degrading SDBS, COD, and ammonia nitrogen, and are suitable for the efficient treatment of black and odorous river bodies.

[0042] (2) Effect of pH on the degradation of photocatalytic suspended materials

[0043] Five groups of experiments were designed. 2 L of water from the river was taken as a black and odorous water sample and placed in a reaction vessel. The initial concentrations of SDBS, COD and ammonia nitrogen in the black and odorous water were 124 mg / L, 298 mg / L and 51 mg / L, respectively. The catalytic material in Example 1 was added and the pH was adjusted to 4, 5, 6, 7 and 8, respectively. Other experimental conditions were the same as those in the above experiment (1). After 2 h of reaction, 10 mL of the sample was taken to detect the concentration of the pollutants after degradation, calculate the degradation rate and draw a degradation curve. The specific results are shown in Figure 4 .

[0044] Depend on Figure 4It can be seen that when the pH is 5-7, the degradation rates of SDBS, COD and ammonia nitrogen by the catalytic material in Example 1 are all above 80%, which indicates that the catalytic material has excellent degradation effects in both weakly acidic and neutral environments and is applicable to a wide range of environments.

[0045] (3) Degradation effect of photocatalytic suspended materials on black and odorous water under natural light

[0046] 2 L of black and odorous water sample was taken from the river and placed in a reaction vessel. The initial concentrations of SDBS, COD and ammonia nitrogen in the black and odorous water were 124 mg / L, 298 mg / L and 51 mg / L, respectively. The catalytic material in Example 1 was added and natural light was used as the light source. Other experimental conditions were the same as those in the above experiment (1). 10 mL of sample was taken every 0.5 h to detect the concentration of pollutants after degradation. The degradation rate was calculated and the degradation curve was drawn. The specific results are shown in Figure 5 .

[0047] according to Figure 5 It can be seen that after 1.5 hours of natural light irradiation, the degradation rates of SDBS, COD and ammonia nitrogen in black and odorous water by the catalytic material in Example 1 are all above 70%, and can reach above 80% after 2.5 hours, with excellent degradation effect.

[0048] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. A photocatalytic suspension material for black and smelly river bodies, characterized in that: The invention comprises a substrate and a catalyst layer, wherein the substrate is a lightweight brick, and the catalyst layer is obtained by coating titanium alkoxide Ti(OC3H7)4 on the surface of the lightweight brick by a sol-gel method; the density of the lightweight brick is 0.5-1.0 g / cm³; The preparation method of the photocatalytic suspension material comprises the following steps: S1, titanium alkoxide Ti(OC3H7)4 and lightweight bricks are added to an organic solvent, and after sufficient stirring, water and organic acid are added to form a sol that combines with the lightweight bricks to obtain titanium dioxide modified lightweight bricks DC-Ti; S2, aging the DC-Ti at room temperature for a period of time to allow the particles to slowly polymerize to form a gel; S3. Drying the aged DC-Ti and calcining it to obtain a photocatalytic suspension material.

2. The photocatalytic suspension material for black and smelly river bodies according to claim 1, characterized in that: The thickness of the catalyst layer is 5-20 μm.

3. The method for preparing a photocatalytic suspension material for black and smelly river bodies according to claim 1, characterized in that: The organic solvent is one of propanol, ethanol or isopropanol, and the organic acid is glacial acetic acid or citric acid.

4. The method for preparing a photocatalytic suspension material for black and smelly river bodies according to claim 1, characterized in that: The mass ratios of titanium alkoxide, lightweight brick, organic solvent, water and organic acid are 1:5~10:2~5:0.5~2:0.1~0.5 respectively.

5. Use of the photocatalytic suspension material according to claim 1 in degrading sodium dodecylbenzene sulfonate, COD and ammonia nitrogen in black and smelly river bodies.

6. The use according to claim 5, characterized in that The pH value of black and smelly rivers is 5~7.

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