Plant-growing concrete based on iron phosphate modified biochar as well as preparation method and application of plant-growing concrete

Abstract

The invention discloses plant-growing concrete based on ferric phosphate modified biochar and a preparation method and application of the plant-growing concrete, and belongs to the technical field of water bank ecological restoration. Preparing a ferric chloride solution, putting the biochar into the ferric chloride solution, reacting for a period of time, taking out the biochar, and activating to obtain activated biochar; putting the activated biochar into industrial phosphorus-containing wastewater to obtain ferric phosphate modified biochar; mixing the ferric phosphate modified biochar with other specified concrete raw materials to prepare plant-growing concrete; according to the invention, the cement consumption is reduced by 25%, the compressive strength is improved, the planting and growth of plants are promoted, and the removal rates of total nitrogen and total phosphorus respectively reach 36% and 40%. The plant-growing concrete based on the iron phosphate modified biochar has a series of advantages of low cost, waste resource utilization, phosphorus resource extraction, high mechanical strength, strong plant-growing performance, excellent water purification performance and the like, and helps to improve and restore the ecological environment of a river bank.

Description

Technical Field

[0001] The invention relates to a vegetative concrete based on iron phosphate modified biochar and a preparation method and application thereof, belonging to the technical field of waterside ecological restoration. Background Art

[0002] On the one hand, the riparian zone is a transition zone between inland water bodies and land, and is the intersection of aquatic ecosystems and terrestrial ecosystems. It not only plays a vital role in soil and water conservation, but also has the ecological function of regulating water quality and purifying pollutants. However, with the increasing intensity of human activities in recent years, the riparian zone ecosystem is facing serious threats. In particular, the discharge of sewage from life and agriculture has led to river pollution, aggravated the eutrophication of water bodies, and significantly reduced the self-purification capacity of water bodies, ultimately leading to ecological degradation of the riparian zone, and even having a profound and negative impact on the surrounding environment.

[0003] On the other hand, concrete production faces huge challenges in resource consumption due to its high demand for energy and raw materials. Studies have shown that the cement production process requires a large amount of energy and mineral resources. It is estimated that by 2030, the production of each ton of cement will consume about 4.3 tons of energy, and nearly 1 ton of greenhouse gases will be released due to high-temperature calcination and chemical reactions. Cement production also requires a large amount of ore raw materials such as limestone, which puts a great pressure on the continuous consumption of natural resources. Therefore, the development of building materials that can replace cement to reduce resource demand and energy consumption in the production process has become an important issue in the field of green building materials.

[0004] At present, one of the common measures used for stabilizing the structure and ecological restoration of riverbanks is to use porous concrete that can be planted with plants. However, ordinary planted concrete usually has disadvantages such as large cement consumption, low compressive strength, poor plant growth, and unsatisfactory water purification effect. It is difficult to effectively meet the current market demand for environmentally friendly, high-strength, strong plant performance, and significant water purification effect riverbank protection materials. Summary of the invention

[0005] The purpose of the present invention is to provide a biochar-modified ferric phosphate-based vegetation concrete and a preparation method and application thereof, so as to solve the problems of low compressive strength, poor vegetation performance and unsatisfactory water purification effect existing in the prior art.

[0006] To achieve the above objectives, the present invention is implemented by adopting the following technical solutions: In a first aspect, the present invention provides a method for preparing bio-concrete based on iron phosphate modified biochar, comprising: preparing biochar; preparing a ferric chloride solution, placing the biochar in the ferric chloride solution to react for a period of time, taking out the biochar and activating it to obtain activated biochar; The activated biochar is placed into industrial phosphorus-containing wastewater to obtain iron phosphate-modified biochar; Iron phosphate modified biochar is mixed with other specified concrete raw materials to make bio-based concrete.

[0007] Furthermore, the preparation of biochar comprises: Agricultural straw and kitchen waste are collected, dried and ground to obtain dry raw materials. The dry raw materials are subjected to microwave pyrolysis under a nitrogen / argon protective atmosphere, and the solid residue is collected and sieved through a 2-5 mm sieve to obtain biochar.

[0008] Furthermore, the ratio of the agricultural straw to the kitchen waste is 2-4:1, the moisture content of the raw material after drying is 5%-10%, and the agricultural straw includes wheat straw and corn straw.

[0009] Furthermore, the microwave pyrolysis includes: setting the power range to 500-1000W, heating to 550-700°C, heating at 550-700°C for 7-9s, and introducing nitrogen or argon at a rate of 0.25-0.3 L / min.

[0010] Further, the preparation of the ferric chloride solution comprises: Mixing waste iron and hydrochloric acid to prepare a ferric chloride solution, and then adding water to dilute the ferric chloride solution; The concentration of the hydrochloric acid is 25-30wt%, and the mass ratio of water to ferric chloride solution during dilution is 1:8-9.

[0011] Furthermore, in the process of placing the biochar in the ferric chloride solution to react for a period of time, the mass ratio of the biochar to the ferric chloride solution is 1:2-4, and the reaction time is 30-36 hours; The method of taking out the biochar and activating it to obtain the activated biochar comprises: placing the biochar in a 14-16wt% calcium chloride solution and activating it for 18-24 hours to obtain the activated biochar.

[0012] Furthermore, the step of placing the activated biochar into industrial phosphorus-containing wastewater to obtain iron phosphate-modified biochar comprises: After the activated biochar is placed in the industrial phosphorus-containing wastewater, if the mass of the biochar increases by no more than 5% within 4 hours, it is taken out to obtain the iron phosphate-modified biochar.

[0013] Furthermore, the iron phosphate modified biochar is mixed with other specified concrete raw materials to prepare bio-concrete, including: 5-25 parts by mass of iron phosphate modified biochar, 70-85 parts by mass of cement, 4-6 parts by mass of fly ash, 4-6 parts by mass of silica fume and 270-290 parts by mass of coarse aggregate are mixed and stirred for 5-8 minutes, 30-45 parts by mass of water are added and stirred for 5-8 minutes, and then 1-3 parts by mass of water reducer are added for 5-8 minutes. The mixed slurry is loaded into a mold and vibrated into shape. After the surface is covered with a film and left to stand for 22-26 hours, it is demolded to obtain vegetation concrete.

[0014] In a second aspect, the present invention provides a biochar-based bio-concrete modified with iron phosphate, which is prepared by any of the methods described in the first aspect.

[0015] In the third aspect, the present invention provides an application of vegetation concrete based on iron phosphate modified biochar, and the vegetation concrete prepared by any method described in the first aspect is applied to the improvement and restoration of the riverbank ecological environment, including: laying 5 to 15 cm of soil on the surface of the vegetation concrete, sowing plants in the soil, and placing it on the riverbank belt.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. The addition of iron phosphate modified biochar can not only improve the mechanical properties of concrete and make its structure denser, thereby enhancing the stability of the slope protection, but also significantly improve the vegetation performance of concrete, release nutrients, and promote rapid colonization and growth of plants, thereby enhancing the ecological benefits of the slope protection.

[0017] 2. Using biochar modified with iron phosphate to replace part of the cement not only reduces carbon emissions, but also the addition of iron phosphate can increase the specific surface area of ​​biochar, improve its phosphorus removal efficiency, promote the activity of functional microorganisms in the soil, help purify water quality, and provide support for the restoration of the ecosystem.

[0018] 3. It not only realizes the green recycling of wastes such as agricultural straw and kitchen waste, but also realizes the extraction of phosphorus resources from sewage and wastewater. Its preparation has the advantages of low cost, resource saving, waste resource utilization, resource extraction, and environmental friendliness. It has significant environmental and economic benefits, especially in improving and restoring the riverbank ecological environment.

[0019] 4. It can effectively reduce carbon emissions, control pollution of rivers and lakes, and promote the recovery and sustainable development of riverside ecological environment; it integrates the multiple advantages of waste resource utilization, sewage and wastewater resource extraction, environmental friendliness, multi-function and efficient ecological restoration, showing extremely high application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of a method for preparing bio-concrete based on iron phosphate modified biochar provided in an embodiment of the present invention; Figure 2 is a schematic diagram for comparing compressive strength provided by an embodiment of the present invention; Figure 3 is a schematic diagram comparing the growth heights of plants at different growth times provided by an embodiment of the present invention; Figure 4 It is a schematic diagram comparing the removal efficiencies of TP and TN provided in the embodiments of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention.

[0022] Example 1.

[0023] like Figure 1 As shown, the present invention provides a method for preparing bio-concrete based on iron phosphate modified biochar, comprising the following steps: Step 1: Collect wheat straw, corn straw and kitchen waste, dry and grind them. The mass ratio of agricultural straw (wheat straw and corn straw) to kitchen waste is 4:1, and dry raw materials are obtained with a moisture content of 5%.

[0024] Step 2: The dried raw material is subjected to microwave pyrolysis under a nitrogen protective atmosphere. The pyrolysis conditions are: power 800 W, heating temperature 550 ° C, heating time 7 s, infrared sensor is used to measure the temperature, and the nitrogen introduction rate is 0.25 L / min. After pyrolysis, the solid residue is collected to obtain biochar and sieved through a 2 mm sieve.

[0025] Step three, mixing the scrap iron with 30wt% hydrochloric acid to prepare a ferric chloride solution, mixing rainwater with the ferric chloride solution to prepare a diluted ferric chloride solution, the weight ratio of rainwater to ferric chloride is 1:9, pouring the sieved biochar into the diluted ferric chloride solution, and draining the ferric chloride after standing for 30 hours. Then, the biochar is placed in 15wt% calcium chloride for activation for 24 hours, and then placed in phosphorus-containing industrial wastewater to capture phosphorus to obtain iron phosphate-modified biochar.

[0026] Step 4: Mix the iron phosphate modified biochar with cement, fly ash, silica fume, coarse aggregate, water reducer and water in a mass ratio of 18:72:5:5:288:2:30 to prepare vegetation concrete, lay a 10 cm soil layer on the concrete surface and sow Bermuda grass seeds.

[0027] The specific steps for making the vegetation concrete in step four are: mix 18 parts by mass of iron phosphate modified biochar, 72 parts by mass of cement, 5 parts by mass of fly ash, 5 parts by mass of silica fume and 288 parts by mass of coarse aggregate for 6 minutes, add 30 parts by mass of water and stir for 6 minutes, then add 2 parts by mass of water reducer for 6 minutes, put the mixed slurry into a mold, vibrate into shape, cover the surface with a film and let it stand for 24 hours before demolding to obtain the vegetation concrete.

[0028] Example 2.

[0029] like Figure 1 As shown, the present invention provides a method for preparing bio-concrete based on iron phosphate modified biochar, comprising the following steps: Step 1: Collect wheat straw, corn straw and kitchen waste, dry and grind them. The mass ratio of agricultural straw (wheat straw and corn straw) to kitchen waste is 4:1, and dry raw materials are obtained with a moisture content of 5%.

[0030] Step 2: The dried raw material is subjected to microwave pyrolysis under a nitrogen protective atmosphere. The pyrolysis conditions are: power 800 W, heating temperature 550 ° C, heating time 7 s, infrared sensor is used to measure the temperature, and the nitrogen introduction rate is 0.25 L / min. After pyrolysis, the solid residue is collected to obtain biochar and sieved through a 2 mm sieve.

[0031] Step three, mixing the scrap iron with 30wt% hydrochloric acid to prepare a ferric chloride solution, mixing rainwater with the ferric chloride solution to prepare a diluted ferric chloride solution, the weight ratio of rainwater to ferric chloride is 1:9, pouring the sieved biochar into the diluted ferric chloride solution, and draining the ferric chloride after standing for 30 hours. Then, the biochar is placed in 15wt% calcium chloride for activation for 24 hours, and then placed in phosphorus-containing industrial wastewater to capture phosphorus to obtain iron phosphate-modified biochar.

[0032] Step 4: Mix the iron phosphate modified biochar with cement, fly ash, silica fume, coarse aggregate, water reducer and water in a mass ratio of 9:81:5:5:288:2:30 to make vegetation concrete, lay a 10 cm soil layer on the concrete surface and sow Bermuda grass seeds.

[0033] The specific steps for making the vegetation concrete in step four are: mix 9 parts by mass of iron phosphate modified biochar, 81 parts by mass of cement, 5 parts by mass of fly ash, 5 parts by mass of silica fume and 288 parts by mass of coarse aggregate for 6 minutes, add 30 parts by mass of water and stir for 6 minutes, then add 2 parts by mass of water reducer for 6 minutes, put the mixed slurry into a mold, vibrate into shape, cover the surface with a film and let it stand for 24 hours before demolding to obtain the vegetation concrete.

[0034] The vegetative concrete prepared in Example 1 and Example 2 was placed in artificially prepared sewage. Bermuda grass was planted on the vegetative concrete, and two groups of controls were used to compare the test results.

[0035] A blank group was set up. The blank group did not contain iron phosphate modified biochar. The mass ratio of cement, fly ash, silica fume, coarse aggregate, water reducer and water was 90:5:5:288:2:30. It was placed in artificial sewage and Bermuda grass was planted on the vegetation concrete.

[0036] Three groups of tests were conducted, and the compressive strength test results were as follows: Figure 2 As shown in the figure, the compressive strength of concrete based on iron phosphate modified biochar is 8.6% higher than that of concrete containing unmodified biochar, and 25% higher than that of concrete without biochar, which is a significant improvement in compressive strength. Figure 3 As shown in the figure, concrete based on iron phosphate modified biochar significantly promoted plant growth, with the maximum growth height at 28 days being about 15 mm, which was 1.48 times and 1.81 times that of concrete containing unmodified biochar and concrete without biochar, respectively. Figure 4 As shown in the data, the removal rates of total nitrogen (TN) and total phosphorus (TP) in polluted water by the biochar-modified iron phosphate concrete reached 36% and 40% respectively within 30 days, which are much higher than those of the biochar-containing unmodified biochar and the biochar-free concrete, and the water purification effect is obvious.

[0037] The test standard for compressive strength is GB / T 50081-2002, and the test standard for total nitrogen and total phosphorus is GB3838-2002.

[0038] The present invention applies the vegetative concrete of biochar modified by iron phosphate to the water ecological restoration of the river bank, thereby simultaneously realizing the effects of waste resource utilization, sewage and wastewater resource extraction, slope protection strength enhancement, ecological vegetation promotion, environmental water quality purification, etc., thereby accelerating the recovery and sustainable development of the river bank ecosystem.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing bio-concrete based on iron phosphate modified biochar, characterized in that: include: preparing biochar; preparing a ferric chloride solution, placing the biochar in the ferric chloride solution to react for a period of time, taking out the biochar and activating it to obtain activated biochar; The activated biochar is placed into industrial phosphorus-containing wastewater to obtain iron phosphate-modified biochar; Iron phosphate modified biochar is mixed with other specified concrete raw materials to make bio-based concrete.

2. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 1, characterized in that: The method for preparing biochar comprises: Agricultural straw and kitchen waste are collected, dried and ground to obtain dry raw materials. The dry raw materials are subjected to microwave pyrolysis under a nitrogen / argon protective atmosphere, and the solid residue is collected and sieved through a 2-5 mm sieve to obtain biochar.

3. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 2, characterized in that: The ratio of the agricultural straw to the kitchen waste is 2-4:1, the moisture content of the raw material after drying is 5%-10%, and the agricultural straw includes wheat straw and corn straw.

4. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 2, characterized in that: The microwave pyrolysis comprises: setting the power range to 500-1000W, raising the temperature to 550-700°C, heating at 550-700°C for 7-9s, and introducing nitrogen or argon at a speed of 0.25-0.3 L / min.

5. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 1, characterized in that: The method for preparing the ferric chloride solution comprises: Mixing waste iron and hydrochloric acid to prepare a ferric chloride solution, and then adding water to dilute the ferric chloride solution; The concentration of the hydrochloric acid is 25-30wt%, and the mass ratio of water to ferric chloride solution during dilution is 1:8-9.

6. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 1, characterized in that: In the process of placing the biochar in the ferric chloride solution to react for a period of time, the mass ratio of the biochar to the ferric chloride solution is 1:2-4, and the reaction time is 30-36 hours; The method of taking out the biochar and activating it to obtain the activated biochar comprises: placing the biochar in a 14-16wt% calcium chloride solution and activating it for 18-24 hours to obtain the activated biochar.

7. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 1, characterized in that: The method of placing activated biochar into industrial phosphorus-containing wastewater to obtain iron phosphate-modified biochar comprises: After the activated biochar is placed in the industrial phosphorus-containing wastewater, if the mass of the biochar increases by no more than 5% within 4 hours, it is taken out to obtain the iron phosphate-modified biochar.

8. The method for producing bio-concrete based on iron phosphate modified biochar according to claim 1, characterized in that: The biochar modified with iron phosphate is mixed with other specified concrete raw materials to make bio-concrete, including: 5-25 parts by mass of iron phosphate modified biochar, 70-85 parts by mass of cement, 4-6 parts by mass of fly ash, 4-6 parts by mass of silica fume and 270-290 parts by mass of coarse aggregate are mixed and stirred for 5-8 minutes, 30-45 parts by mass of water are added and stirred for 5-8 minutes, and then 1-3 parts by mass of water reducer are added for 5-8 minutes. The mixed slurry is loaded into a mold and vibrated into shape. After the surface is covered with a film and left to stand for 22-26 hours, it is demolded to obtain vegetation concrete.

9. A bio-concrete based on iron phosphate modified biochar, characterized in that: The method is prepared by any one of claims 1 to 8.

10. An application of bio-concrete based on iron phosphate modified biochar, characterized in that: The vegetative concrete prepared by the method described in any one of claims 1 to 8 is applied to the improvement and restoration of the riverbank ecological environment, comprising: laying 5 to 15 cm of soil on the surface of the vegetative concrete, sowing plants in the soil, and placing it on the riverbank.

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