Cement-based porous adsorption material doped with oyster shell powder and application of cement-based porous adsorption material in red tide prevention and control

Abstract

The invention discloses a cement-based porous adsorption material doped with oyster shell powder and application of the cement-based porous adsorption material in red tide prevention and control. The method comprises the following steps: cleaning waste oyster shells with pure water, drying, grinding and sieving to prepare oyster shell powder; mixing the oyster shell powder with cement, and fully stirring to obtain dry mixed powder; mixing pure water with the dry-mixed powder, and stirring at a low speed to prepare neat paste; preparing tea saponin into an aqueous solution by using pure water, and foaming by using a foaming machine to prepare a foam material; and mixing the foam material with the neat paste, quickly stirring, pouring into a mold, pre-curing to form a blank, demolding, transferring into a curing chamber, curing to a specified age, and taking out to obtain the cement-based porous adsorption material. The cement-based porous adsorption material has excellent adsorption performance on algicidal bacteria, and can effectively immobilize the algicidal bacteria so as to achieve the effect of preventing and controlling red tide.

Description

Technical Field

[0001] The invention relates to the technical field of environmentally friendly materials, and in particular to a cement-based porous adsorption material admixed with oyster shell powder and application thereof in red tide prevention and control. Background Art

[0002] Red tide is a serious marine environmental pollution phenomenon, mainly due to the excessive growth of certain algae, which leads to abnormal changes in the color of seawater. Red tide not only causes serious damage to fishery resources, but also has a negative impact on the marine ecosystem and even poses a threat to human health. In recent years, with the impact of global climate change and human activities, the frequency and scale of red tides have continued to increase, becoming a major environmental problem that needs to be solved urgently.

[0003] Algicidal bacteria are a type of bacteria that have the ability to dissolve algae cell walls and are the main way to prevent and control red tides. Bacteria can not only inhibit algae growth by competing with algae for nutrients, but also inhibit algae growth or kill algae by secreting certain extracellular active substances into the environment.

[0004] Microbial immobilization technology is a method that limits free microbial cells to a limited area, so that the microorganisms can remain active and reused within a certain spatial range. Compared with traditional suspended organisms, it has the advantages of high treatment effect, fast speed, strong stability, low sludge production, and good solid-liquid separation. The adsorption carrier can provide a matrix for the growth and reproduction of algae-lytic bacteria, ensuring the stable growth of algae-lytic bacteria. In actual algae removal applications, the construction of an immobilized microbial algae removal system provides support and protection for the growth and reproduction of algae-lytic bacteria, which can effectively improve the algae removal efficiency of algae-lytic bacteria and ensure the stable growth of algae-lytic bacteria. The pore size of cement-based porous adsorption materials can vary from nanometers to millimeters. The wide range of pore distribution determines that cement-based materials have special adsorption properties, and the adsorption properties of the cement matrix will affect the transmission of water, volume expansion and contraction, ion exchange, chemical reactions and other processes, so the adsorption characteristics are a very important property of cement-based materials. The adsorption characteristics of cement-based materials are closely related to their microstructure. The present invention utilizes the internal pores of lightweight aggregate (oyster shell powder) and the characteristics of a large number of micro-voids generated by the accumulation of lightweight aggregates. By mixing prefabricated lightweight aggregate with cement, a cement-based porous adsorption material with a stable pore structure is prepared; the calcium and other trace elements in the oyster shell powder increase the specific surface area of ​​the material, increase the adsorption sites of the material, promote the formation of pores inside the material, increase the porosity and specific surface area of ​​the material, and further enhance the adsorption performance of the material. The cement-based porous adsorption material prepared by the method of the present invention is not only superior to saponin-based porous foam concrete in terms of material properties, including specific surface area, porosity, and compressive strength, but also can save costs and mitigate environmental problems caused by the accumulation and flooding of oyster shells. The present invention further adsorbs immobilized algae-lysing bacteria on the prepared cement-based porous adsorption material to establish an algae removal system, which can effectively reduce the biomass of red tide algae. Summary of the invention

[0005] The present invention aims to provide a cement-based porous adsorption material admixed with oyster shell powder and its application in red tide prevention and control. Specifically, the present invention uses waste oyster shell powder as an external admixture, mixes it with cement and adds tea saponin foaming agent to prepare a porous adsorption material with high adsorption performance and large specific surface area, which can meet the application requirements of red tide disaster prevention and mitigation under different sea conditions.

[0006] To achieve the above object, the present invention adopts the following technical solution: The first aspect of the present invention provides a method for preparing a cement-based porous adsorption material admixed with oyster shell powder, comprising the following steps: S1: The discarded oyster shells are cleaned with pure water, dried, ground and sieved to obtain oyster shell powder; S2: fully mixing oyster shell powder and cement to prepare dry mixed powder; S3: Mix pure water with the dry-mixed powder materials and stir at a low speed to obtain neat paste. S4: Prepare an aqueous solution of tea saponin with pure water, and foam it with a foaming machine to obtain a foam material. S5: Mix the foam material with the neat paste, stir quickly, pour it into a mold, demold after pre-curing to form a blank, then transfer it to a curing room for curing until the specified age and take it out to obtain a cement-based porous adsorbent material. Further, in step S2, the mass ratio of oyster shell powder to cement is 4 - 20:80 - 96. Further, in step S3, the ratio of pure water to the dry-mixed powder materials is 0.5 - 0.7 L / 1 kg; the stirring speed is 140 ± 5 r / min and the time is 60 s. Further, in step S4, the concentration of the tea saponin aqueous solution is 40.4 wt%; the aeration pressure of the foaming machine is 0.8 MPa, the aeration rate is 5 L / min, and the foaming time is 5 min. Further, in step S5, the ratio of the foam material to the neat paste is 0.9 - 1.7 L / 1 kg; the stirring speed is 285 ± 10 r / min and the time is 180 s.

[0007] The second aspect of the present invention provides a cement-based porous adsorbent material doped with oyster shell powder, which is prepared by the above preparation method. Further, the density of the prepared cement-based porous adsorbent material is 329 - 532 kg / m 3 , the compressive strength is 0.49 - 1.64 MPa, the water absorption rate is 36.9% - 72.33%, the porosity is 67.2% - 76.3%, the average pore diameter is 0.25 - 0.4 mm, and the specific surface area is 29.7 - 59.70 m 2 / g.

[0008] The third aspect of the present invention provides the application of the above cement-based porous adsorbent material doped with oyster shell powder in red tide prevention and control. Further, the cement-based porous adsorbent material can reduce the biomass of red tide algae by immobilizing and adsorbing algicidal bacteria, thereby achieving red tide prevention and control.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Using waste oyster shell powder as raw material, the cost is low and it is easy to obtain. By using waste oyster shell powder, not only the raw material cost is reduced, but also the recycling of resources is realized, and the impact of waste on the environment is reduced. At the same time, the used foaming material tea saponin is a natural and environmentally friendly material and will not cause secondary pollution to the environment. (2) Oyster shell powder contains rich calcium and other trace elements, which can significantly improve the adsorption performance and specific surface area of the material.

[0010] (3) The cement-based porous adsorbent material can immobilize and adsorb algicidal bacteria. The material has good stability and can be reused. The cement-based porous adsorbent material after immobilizing and adsorbing algicidal bacteria shows good stability and adsorption effect in practical applications.

[0011] (4) This cement-based porous adsorbent material is not only applicable to red tide prevention and control, but also can be applied to other water treatment fields, such as sewage treatment, drinking water purification, etc. Description of the Drawings

[0012] Figure 1 : Influence of the dosage of oyster shell powder on the performance of the cement-based porous adsorbent material.

[0013] Figure 2 : SEM images of the cement-based porous adsorbent material (the dosage of foam material is 1100ml, 1300ml, 1500ml, and 1700ml in sequence for a-d).

[0014] Figure 3 : Adsorption effect of the cement-based porous adsorbent material immobilizing and adsorbing algicidal bacteria.

[0015] Figure 4 : a: Appearance image of the cement-based porous adsorbent material; b: SEM image of the distribution of algicidal bacteria on the surface of the cement-based porous adsorbent material; c: SEM image of the distribution of algicidal bacteria in the pores of the cement-based porous adsorbent material.

[0016] Figure 5 : Algae-lysing effect diagram of the cement-based porous adsorbent material immobilizing and adsorbing algicidal bacteria. Detailed Embodiments

[0017] The present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention. Unless otherwise specified, the test methods involved in the present invention are all conventional methods in the art. For example, referring to "JG / T 266-2011 Foamed Concrete", the material is made into standard test blocks with a specification of 100mm×100mm×100mm for performance testing.

[0018] The cement involved in the present invention is Conch brand P.O 42.5 ordinary Portland cement; the tea saponin involved in the present invention is industrial-grade tea saponin, produced by Anhui YingShanHong Biotechnology Co., Ltd.

[0019] The present invention provides a preparation method of a cement-based porous adsorbent material for red tide prevention and control, including the following steps: S1: Wash the waste oyster shells with pure water, dry them, grind them and sieve them to obtain oyster shell powder; S2: Mix the oyster shell powder and cement, and stir well to obtain a dry mixed powder; S3: Mix pure water and dry mixed powder, stir at low speed to obtain a pure slurry; S4: preparing tea saponin into an aqueous solution with pure water, and foaming it in a foaming machine to obtain a foam material; S5: Mix the foam material with the clean slurry, stir quickly, pour into a mold, demould after pre-forming into a green body, and then transfer to a standard curing room or a dry curing box and take out after curing to a specified age to obtain a cement-based porous adsorption material.

[0020] Embodiment 1: This embodiment provides a method for preparing a cement-based porous adsorption material, which is carried out according to the following steps: S1: The discarded oyster shells were cleaned with pure water, dried at 60°C for 24 h, and ground through a 300-mesh sieve to obtain oyster shell powder; S2: Mix oyster shell powder and cement in a mass ratio of 4:96 (i.e., the amount of oyster shell powder is 4wt% of the sum of the mass of oyster shell powder and cement), 8:92 (i.e., the amount of oyster shell powder is 8wt% of the sum of the mass of oyster shell powder and cement), 12:88 (i.e., the amount of oyster shell powder is 12wt% of the sum of the mass of oyster shell powder and cement), 16:84 (i.e., the amount of oyster shell powder is 16wt% of the sum of the mass of oyster shell powder and cement), and 20:80 (i.e., the amount of oyster shell powder is 20wt% of the sum of the mass of oyster shell powder and cement), stir well, and prepare a dry mixed powder; S3: Pure water and dry mixed powder were mixed at a ratio of 0.6L / 1kg, and stirred at 140±5r / min for 60s to obtain a pure slurry; S4: tea saponin is prepared into an aqueous solution with a concentration of 0.4 wt % with pure water, and foamed for 5 min in a foaming machine (aeration pressure 0.8 MPa, aeration volume 5 L / min) to obtain a foam material; S5: Mix the foam material and the pure slurry in a ratio of 1L / 1kg, stir at 285±10r / min for 180s, pour into the mold, pre-form the blank at 20±2℃ for 48h, demould, and transfer to a curing box (temperature 20±2℃, humidity 60±5%) for standard curing until the specified curing age of 28d, then take out to obtain a cement-based porous adsorption material.

[0021] Depend on Figure 1 It can be seen that with the increase of oyster shell powder content, the density and compressive strength of cement-based porous adsorption material gradually decrease, and the water absorption rate gradually increases; when the oyster shell powder content is 20wt% of the sum of the mass of oyster shell powder and cement, the density of cement-based porous adsorption material is 501kg / m 3 , the compressive strength is 1.39MPa, and the water absorption rate is 59.1%. The addition of oyster shell powder can improve the water absorption of cement-based porous adsorption materials, which is conducive to better adsorption of algae-lysing bacteria, and thus is beneficial to subsequent adsorption applications.

[0022] Embodiment 2: This embodiment provides a method for preparing a cement-based porous adsorption material, which is carried out according to the following steps: S1: The discarded oyster shells were cleaned with pure water, dried at 60°C for 24 h, and ground through a 300-mesh sieve to obtain oyster shell powder; S2: mixing oyster shell powder and cement in a mass ratio of 20:80 (i.e., the amount of oyster shell powder is 20wt% of the sum of the mass of oyster shell powder and cement), and stirring thoroughly to obtain a dry mixed powder; S3: Mix pure water and dry mixed powder at a ratio of 0.6L / 1kg, and stir at 140±5r / min for 60s to obtain a pure slurry; S4: tea saponin is prepared into an aqueous solution with a concentration of 0.4 wt % with pure water, and foamed for 5 min in a foaming machine (aeration pressure 0.8 MPa, aeration volume 5 L / min) to obtain a foam material; S5: Mix the foam material and the pure slurry in the proportion of 0.9L / 1kg, 1.1L / 1kg, 1.3L / 1kg, 1.5L / 1kg and 1.7L / 1kg, stir at 285±10r / min for 180s, pour into the mold, pre-grow the blank at 20±2℃ for 48h, then demould, transfer to a curing box (temperature 20±2℃, humidity 60±5%) for standard curing until the specified curing age of 28d, then take out to obtain the cement-based porous adsorption material.

[0023] As can be seen from Table 1, with the increase of foam material content, the density of the material gradually decreases, the water absorption rate and specific surface area gradually increase, and the compressive strength decreases slightly. When the foam material content is 1.7L, the density of the cement-based porous adsorption material drops to 329kg / m 3 , the water absorption rate increased to 72.33%, the compressive strength decreased to 0.49MPa, and the specific surface area increased to 59.70m 2 / g, porosity increased to 76.3%, and the average pore size was 0.4mm. Density and compressive strength were negatively correlated with the foam material ratio, while water absorption, average pore size, porosity, and specific surface area were positively correlated with the foam material ratio. The increase in specific surface area provided more adsorption sites for algae-lysing bacteria, and water absorption and porosity also reflected that there was more space in the material for gas or liquid molecules to enter, which enhanced the adsorption effect.

[0024] Table 1 Effect of foam material dosage ratio on the performance of cement-based porous adsorption materials Depend on Figure 2 It can be seen that the obtained cement-based porous adsorption material has a large number of pores and the pores are evenly distributed, which is beneficial to improving the overall adsorption efficiency of the material.

[0025] Embodiment 3: A method for preparing a cement-based porous adsorption material is carried out according to the following steps: S1: The discarded oyster shells were cleaned with pure water, dried at 60°C for 24 h, and ground through a 300-mesh sieve to obtain oyster shell powder; S2: mixing oyster shell powder and cement in a mass ratio of 20:80 (i.e., the amount of oyster shell powder is 20wt% of the sum of the mass of oyster shell powder and cement), and stirring thoroughly to obtain a dry mixed powder; S3: Pure water and dry mixed powder were mixed at a ratio of 0.6L / 1kg, and stirred at 140±5r / min for 60s to obtain a pure slurry; S4: tea saponin is prepared into an aqueous solution with a concentration of 0.4 wt % with pure water, and foamed for 5 min in a foaming machine (aeration pressure 0.8 MPa, aeration volume 5 L / min) to obtain a foam material; S5: Mix the foam material and the pure slurry at a ratio of 1.7L / 1kg, stir at 285±10r / min for 180s, pour into the mold, pre-form the blank at 20±2℃ for 48h, demould, and transfer to a curing box (temperature 20±2℃, humidity 60±5%) for standard curing until the specified curing age of 28d, then take out to obtain a cement-based porous adsorption material.

[0026] The prepared cement-based porous adsorption material was cut into carrier test blocks of 100 mm × 100 mm × 100 mm, dried at 60 ° C for 48 h, sterilized by ultraviolet radiation for 4 h, and then added to 100 mL of algicidal bacteria solution in the logarithmic growth period (Pseudoalteromonas sp. Strain FDHY-MZ2: An Effective Strategy for Increasing Algicidal Activity [J]. Biology (2079-7737), 2023, 12 (11). DOI: 10.3390 / biology12111447.) for static adsorption. Samples were taken at regular intervals, and the carrier test blocks with different sampling times were added to sterile seawater with the same liquid absorption amount and appropriate volume ratio, and then ultrasonicated for 15 min and the OD was measured. 600 At the same time, the algicidal bacteria solution at different sampling times was appropriately diluted and placed in a cuvette, and measured at a wavelength of 600nm to make its absorbance value within the range of 0.2 to 0.8, and the dilution multiple and absorbance value were recorded.

[0027] Depend on Figure 3It can be seen that the length of the adsorption time has little effect on the liquid absorption capacity of the cement-based porous adsorption material. The liquid absorption capacity of the cement-based porous adsorption material reaches the maximum value of 1.42 mL / g at 24 h. The OD value measured after ultrasonic treatment of the cement-based porous adsorption material after adsorption is the largest at 12 h, indicating that the biomass of the algicidal bacteria adsorbed by the cement-based porous adsorption material is the highest after 12 h of immobilized adsorption, reaching the adsorption equilibrium. The change in the OD value of the algicidal bacteria solution is not obvious, indicating that the cement-based porous adsorption material has no effect on the growth of the algicidal bacteria. 600 value is the largest at 12 h, indicating that the biomass of the algicidal bacteria adsorbed by the cement-based porous adsorption material is the highest after 12 h of immobilized adsorption, reaching the adsorption equilibrium. The OD 600 value of the algicidal bacteria solution does not change significantly, indicating that the cement-based porous adsorption material has no effect on the growth of the algicidal bacteria.

[0028] Example 4: Taking the red tide alga Karenia mikimotoi as the experimental object, the cement-based porous adsorption material prepared in Example 3 was cut into carrier test blocks of 100 mm×100 mm×100 mm, dried at 60 °C for 48 h, sterilized by ultraviolet radiation for 4 h, and then added to 100 mL of the logarithmic growth phase Pseudoalteromonas sp. FDHY-MZ2 bacterial solution and allowed to stand for adsorption for 12 h. Then, the adsorbed test blocks were co-cultured with the logarithmic growth phase Karenia mikimotoi solution at a volume ratio of 1:150. A blank control was set, and the blank control was an equal volume of the logarithmic growth phase Karenia mikimotoi solution without adding test blocks. Three replicates were set for both the experimental group and the control group. When the algicidal rate reached 100%, an equal amount of the logarithmic growth phase Karenia mikimotoi solution was immediately replaced, and samples were taken regularly. Each time, 1 mL of the culture solution was taken for algal cell concentration counting until the algicidal effect was not obvious.

[0029] As Figure 4 can be seen, after the cement-based porous adsorption material and the algicidal bacteria were adsorbed and fixed for 12 h, the material adsorbed with bacteria was immersed in 2.5% glutaraldehyde for 12 h, washed 3 times with deionized water, and then dehydrated with 30%, 50%, 70%, 85%, and 90% ethanol (prepared freshly) for 10 min respectively, and then dehydrated with 100% ethanol 2 times, 10 min each time; dried, air-dried naturally at room temperature and photographed with an electron microscope (acceleration voltage: 3 kV, magnification: 5000 times). It can be seen that a large number of bacteria are attached to the surface and inside the pores of the material, indicating that the cement-based porous adsorption material has good adsorption performance.

[0030] As Figure 5It can be seen that after the cement-based porous adsorbent material and the algicidal bacteria are adsorbed and fixed for 12 hours and then added to Karenia mikimotoi in the logarithmic growth phase, the algicidal efficiency reaches 100% at 6 hours in the first three algicidal experiments. The third algicidal experiment takes 15 hours, and the fifth one takes 36 hours. As the number of uses increases, the algicidal effect gradually weakens within the corresponding time period. Generally speaking, the cement-based porous adsorbent material can be repeatedly used as the adsorption carrier of the algicidal bacteria in the prevention and mitigation of red tides, and has a good algicidal effect. It can be seen that the cement-based porous adsorbent material of the present invention can be used as the adsorption carrier of the algicidal bacteria to reduce the biomass of red tide algae and is used for the prevention and mitigation of red tides.

[0031] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a cement-based porous adsorption material admixed with oyster shell powder, characterized in that: The following steps are involved: S1: The discarded oyster shells are cleaned with pure water, dried, ground and sieved to obtain oyster shell powder; S2: fully mixing oyster shell powder and cement to prepare dry mixed powder; S3: Mix pure water and dry mixed powder, stir at low speed to obtain a pure slurry; S4: preparing tea saponin into an aqueous solution with pure water, and foaming it in a foaming machine to obtain a foam material; S5: Mix the foam material with the clean slurry, stir quickly, pour into a mold, demould after pre-forming into a blank, and then transfer to a curing room for curing to a specified age and then take out to obtain a cement-based porous adsorption material.

2. The preparation method according to claim 1, characterized in that: In step S2, the mass ratio of oyster shell powder to cement is 4-20:80-96.

3. The preparation method according to claim 1, characterized in that: In step S3, the ratio of pure water to dry mixed powder is 0.5-0.7 L / 1 kg; the stirring speed is 140±5 r / min, and the time is 60 s.

4. The preparation method according to claim 1, characterized in that: In step S4, the concentration of the tea saponin aqueous solution is 40.4 wt %; the aeration pressure of the foaming machine is 0.8 MPa, the aeration volume is 5 L / min, and the foaming time is 5 min.

5. The preparation method according to claim 1, characterized in that: In step S5, the ratio of the foam material to the clean slurry is 0.9-1.7 L / 1 kg; the stirring speed is 285±10 r / min, and the time is 180 s.

6. A cement-based porous adsorption material admixed with oyster shell powder, characterized in that: Prepared by the preparation method according to any one of claims 1 to 5.

7. The cement-based porous adsorption material according to claim 6, characterized in that: The density of cement-based porous adsorption materials is 329~532kg / m 3 The compressive strength is 0.49~1.64MPa, the water absorption rate is 36.9%~72.33%, the porosity is 67.2%~76.3%, the average pore size is 0.25~0.4mm, and the specific surface area is 29.7~59.70m 2 / g.

8. Use of the cement-based porous adsorption material according to any one of claims 6 to 7 in red tide prevention and control.

9. The use according to claim 8, characterized in that: Cement-based porous adsorption materials can reduce the biomass of red tide algae by immobilizing and adsorbing algae-lysing bacteria, thereby achieving red tide prevention and control.

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