Paeonia lactiflora straw biochar composite material with removal effect on hexavalent chromium in water body

Abstract

The invention relates to the technical field of combustion improvers, in particular to a Chinese herbaceous peony straw biochar composite material with a removal effect on hexavalent chromium in water, which is prepared from the following raw materials in parts by weight: 60 to 80 parts of biochar main materials, 10 to 20 parts of first auxiliary materials, 5 to 10 parts of second auxiliary materials, 5 to 10 parts of binding materials and 2 to 6 parts of third auxiliary materials. According to the composite material, multiple auxiliary materials and the charcoal main material cooperate, so that the composite material can avoid interference of other ions and accurately adsorb hexavalent chromium in a complex water body, the treatment efficiency and pertinence are greatly improved, the problem that a traditional adsorption material is poor in selectivity is effectively solved, and in complex environments with different temperatures, acidity and alkalinity and the like, the composite material has a good adsorption effect on hexavalent chromium. Good structure and performance can be maintained, the application scene is expanded, the use limitation is reduced, and a reliable guarantee is provided for actual water body restoration.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion improvers, and specifically to a peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies. Background Art

[0002] Hexavalent chromium in water bodies is a highly toxic heavy metal pollutant, which widely exists in industrial wastewaters such as electroplating and metallurgy. It has high water solubility and strong oxidizing properties, and is extremely easy to be absorbed by organisms and accumulate in the body. After hexavalent chromium enters the human body, it will cause respiratory inflammation, skin ulcers, and even cancer and teratogenesis, posing a serious threat to human health. At the ecological level, it will damage the physiological functions of aquatic organisms, lead to a reduction in species, and seriously affect the balance of the water ecosystem. Therefore, it is urgent to remove hexavalent chromium in water bodies.

[0003] In the prior art, activated carbon materials are usually used to remove hexavalent chromium in water bodies. Ordinary activated carbon mainly relies on physical pores for adsorption and lacks specific adsorption sites for hexavalent chromium. In complex water bodies, a large number of coexisting other anions, such as sulfate ions and chloride ions, will compete with hexavalent chromium for adsorption sites, resulting in a significant reduction in the adsorption efficiency of hexavalent chromium.

[0004] Based on this, the present invention provides a peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies. Summary of the Invention

[0005] The purpose of the present invention is to provide a peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies, comprising the following raw materials in parts by weight: 60 - 80 parts of a biochar main material, 10 - 20 parts of a first auxiliary material, 5 - 10 parts of a second auxiliary material, 5 - 10 parts of a binder, and 2 - 6 parts of a third auxiliary material; The preparation method comprises the following steps: S1: Weigh the biochar main material, the first auxiliary material, the second auxiliary material, and the third auxiliary material as required and mix them to obtain a mixture; S2: Put the mixture into a blender, then add the binder, and stir at 100 - 300 r / min for 30 - 60 min to obtain a slurry; S3: Inject the slurry into a mold, dry and cure it at a pressure of 10 - 30 MPa and a temperature of 60 - 100 °C for 4 - 8 h, then cool it to room temperature, and demold to obtain a peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies.

[0007] Preferably, the preparation method of the first auxiliary material comprises the following steps: Step 1: Select orange peel as the raw material. After drying, it is crushed to 20 - 50 mesh and then added to a stirring tank. Deionized water and saccharifying enzyme are added, and it is stirred at 50 - 100 r / min for 1 - 2 h. Then it is transferred to a fermentation tank and fermented at 30 - 45 °C for 5 - 7 d. After that, impurities are filtered to obtain the fermentation broth; Step 2: Select clay particles with a particle size of 20 - 50 mesh as the raw material, add them to the fermentation broth and soak for 24 - 48 h. Then it is dried at 80 - 120 °C to obtain dry particles; Step 3: Transfer the dry particles to a muffle furnace, heat them at a heating rate of 2 - 5 °C / min to 400 - 600 °C, calcine for 2 - 4 h and then cool to room temperature. After that, it is crushed by a crusher and sieved through a 100 - 200 mesh sieve to obtain the first auxiliary material.

[0008] Preferably, in Step 1, the mass ratio of orange peel to deionized water is 1:(5 - 10), and the saccharifying enzyme accounts for 0.1 - 0.5% of the weight of orange peel. In Step 2, the mass ratio of clay particles to fermentation broth is 1:(3 - 5).

[0009] Preferably, the preparation method of the second auxiliary material includes the following steps: Step 1: Select waste ceramic material as the raw material. After cleaning and drying, it is crushed to 50 - 100 mesh, and then added to a hydrochloric acid solution with a mass fraction of 5 - 15% and soaked for 2 - 4 h. Then it is washed with water until neutral and dried to obtain the first ceramic powder; Step 2: Mix the ceramic powder and ferrous sulfate solution according to a solid - liquid ratio of 1:(3 - 5) and add them to a stirring kettle. Stir at 200 - 400 r / min for 1 - 3 h, then add sodium hydroxide to adjust the pH to 9 - 11. After centrifugal filtration, the precipitate is taken, which is the second ceramic powder; Step 3: Dry the second ceramic powder at 100 - 150 °C, then transfer it to a rotary kiln, heat it at a heating rate of 3 - 8 °C / min to 350 - 500 °C, calcine for 1 - 2 h and then cool to room temperature. After that, it is crushed by a crusher and sieved through a 200 - 400 mesh sieve to obtain the second auxiliary material.

[0010] Preferably, in Step 1, the solid - liquid ratio of the waste ceramic material to the hydrochloric acid solution is 1:(5 - 10). In Step 2, the concentration of the ferrous sulfate solution is 0.5 - 2 mol / L. In Step 3, the rotation speed of the rotary kiln is 5 - 10 r / min.

[0011] Preferably, the preparation method of the third auxiliary material includes the following steps: Step a: Select pine sawdust as the raw material, add it to a sodium hydroxide solution with a mass fraction of 5 - 10% and mix. Stir at 90 - 100 °C and 300 - 500 r / min for 2 - 4 h, filter to remove the solid matter to obtain the extract; Step b: Select rosin as the raw material and crush it to 50-100 mesh. Mix it with the extraction solution, then add a sulfuric acid solution with a mass fraction of 1-5% to adjust the pH to 2-4. Then, stir and react at 60-80 °C and 20-50 r / min for 1-2 h to obtain a mixed solution; Step c: Cool the mixed solution to room temperature, then add absolute ethanol and let it stand for 2-4 h. After filtration, take the precipitate and put it into a drying oven, dry it at 50-80 °C, and then crush it to 1-5 mm by a crusher to obtain the third auxiliary material.

[0012] Preferably, in step a, the solid-liquid ratio of pine sawdust to sodium hydroxide solution is 1:(8-12); in step b, the solid-liquid ratio of rosin to the extraction solution is 1:(2-4); the addition amount of the sulfuric acid solution is 0.5-2% of the total weight of rosin and the extraction solution; in step c, the mass ratio of the mixed solution to absolute ethanol is 1:(2-4).

[0013] Preferably, the preparation method of the biochar main material includes the following steps: Step A: Raw material pretreatment. Select peony and straw as the raw materials, crush them to 20-50 mesh, soak them in a phosphoric acid solution with a mass fraction of 3-10% for 6-12 h, then wash them with water until neutral and dry them to obtain the treated material; Step B: Carbonization and calcination. Place the treated material in a carbonization furnace, introduce nitrogen for protection, heat it at a heating rate of 5-10 °C / min to 450-650 °C, keep it warm for 1-3 h and then cool it to room temperature. Then, crush it by a crusher and pass it through a 100-300 mesh sieve to obtain the biochar raw material; Step C: Mix the biochar raw material with a hydrochloric acid solution with a mass fraction of 5-15% according to a solid-liquid ratio of 1:(5-10), stir at a speed of 100-300 r / min, stir for 1-2 h, then wash and dry it to obtain the biochar main material.

[0014] Preferably, the binder is prepared by mixing an aqueous binder, reinforcing fibers and a plasticizer in a mass ratio of 5:3:1. Among them, the aqueous binder can be at least one of polyvinyl alcohol, sodium carboxymethyl cellulose and starch glue; the reinforcing fibers can be at least one of wood fibers or glass fibers with a fiber length of 1-5 mm; the plasticizer can be at least one of glycerol or dibutyl phthalate.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the present invention, the first auxiliary material treats clay with orange peel fermentation broth. The organic acids produced by fermentation not only change the surface properties of the clay, but also introduce specific organic functional groups. These functional groups can specifically bind to hexavalent chromium ions, improving the adsorption selectivity for hexavalent chromium. The iron-modified ceramic material of the second auxiliary material has a certain specificity when its iron-based active phase undergoes an oxidation-reduction reaction with hexavalent chromium, preferentially reducing hexavalent chromium. The phenolic hydroxyl groups, carboxyl groups, etc. contained in the third auxiliary material can also form stable coordination bonds with hexavalent chromium. The cooperation of various auxiliary materials and the biochar main material enables the composite material to avoid the interference of other ions in complex water bodies, accurately adsorb hexavalent chromium, greatly improving the treatment efficiency and targeting, and effectively solving the problem of poor selectivity of traditional adsorption materials.

[0016] 2. In the present invention, through the careful design of each component and the preparation process, the composite material is given good environmental adaptability. The composite structure of the first auxiliary material can maintain a stable surface charge and pore structure in different pH environments, ensuring stable adsorption performance. The iron-based active phase of the second auxiliary material has mild reaction conditions during the oxidation-reduction process and is not overly interfered by common components in the water body, ensuring the stable removal of hexavalent chromium. The rosin derivative of the third auxiliary material has a certain corrosion resistance and can maintain the stability of its own structure under various water quality conditions, reducing the influence of competitive anions. The three-dimensional network structure formed by the binder further stabilizes each component, enabling the composite material to maintain good structure and performance in complex environments such as different temperatures and pH values, expanding the application scenarios and reducing the usage limitations, providing a reliable guarantee for actual water body restoration. Specific Embodiments

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0018] Example 1. This example provides a paeonia lactiflora straw biochar composite material with a removal effect on hexavalent chromium in water bodies, including the following raw materials in parts by weight: 60 parts of biochar main material, 10 parts of first auxiliary material, 5 parts of second auxiliary material, 5 parts of binder, and 2 parts of third auxiliary material; The preparation method includes the following steps: S1: Weigh the biochar main material, first auxiliary material, second auxiliary material, and third auxiliary material as needed and mix them to obtain a mixture. S2: Put the mixture into a blender, then add the binder, and stir at 100 r / min for 30 min to obtain a slurry. S3: Inject the slurry into the mold, dry and cure it at a pressure of 10 MPa and a temperature of 60 °C for 4 h, then cool it to room temperature and demold to obtain the peony straw biochar composite with the effect of removing hexavalent chromium in water.

[0019] Among them, the preparation method of the first auxiliary material includes the following steps: Step 1: Select orange peel as the raw material, dry and crush it to 20 mesh, then add it to the stirring tank, add deionized water and glucoamylase, stir at 50 r / min for 1 h, then transfer it to the fermentation tank, ferment at 30 °C for 5 d, and then filter out impurities to obtain the fermentation broth; Step 2: Select clay particles with a particle size of 20 - 50 mesh as the raw material, add them to the fermentation broth and soak for 24 h, then dry at 80 °C to obtain dry particles; Step 3: Transfer the dry particles to a muffle furnace, heat them up to 400 °C at a heating rate of 2 °C / min, calcine for 2 h, then cool to room temperature, and then crush them through a crusher and pass through a 100 - mesh sieve to obtain the first auxiliary material.

[0020] Among them, in Step 1, the mass ratio of orange peel to deionized water is 1:5, and the glucoamylase accounts for 0.1% of the weight of the orange peel. In Step 2, the mass ratio of clay particles to the fermentation broth is 1:3.

[0021] Among them, the preparation method of the second auxiliary material includes the following steps: Step 1: Select waste ceramic material as the raw material, wash, dry and crush it to 50 mesh, then add it to a 5% hydrochloric acid solution by mass and soak for 2 h, then wash it with water until neutral and dry it to obtain the first ceramic powder; Step 2: Mix the ceramic powder and ferrous sulfate solution at a solid - liquid ratio of 1:3 and add them to the stirring kettle, stir at 200 r / min for 1 h, then add sodium hydroxide to adjust the pH to 9, and take the precipitate after centrifugal filtration, which is the second ceramic powder; Step 3: Dry the second ceramic powder at 100 °C, then transfer it to a rotary kiln, heat it up to 350 °C at a heating rate of 3 °C / min, calcine for 1 h, then cool to room temperature, and then crush it through a crusher and pass through a 200 - mesh sieve to obtain the second auxiliary material.

[0022] Among them, in Step 1, the solid - liquid ratio of waste ceramic material to hydrochloric acid solution is 1:5. In Step 2, the concentration of ferrous sulfate solution is 0.5 mol / L. In Step 3, the rotation speed of the rotary kiln is 5 r / min.

[0023] Among them, the preparation method of the third auxiliary material includes the following steps: Step a: Select pine sawdust as the raw material, mix it with a 5% sodium hydroxide solution by mass, stir at 90 °C and 300 r / min for 2 h, filter out the solid matter to obtain the extract; Step b: Select rosin as the raw material, crush it to 50 mesh, mix it with the extraction solution, then add a sulfuric acid solution with a mass fraction of 1% to adjust the pH to 2, and then stir and react at 60 °C and 20 r / min for 1 h to obtain a mixed solution; Step c: Cool the mixed solution to room temperature, then add anhydrous ethanol and let it stand for 2 h. After filtration, take the precipitate and put it into a drying oven, dry it at 50 °C, and then crush it to 1 mm by a crusher to obtain the third auxiliary material.

[0024] Among them, in step a, the solid-liquid ratio of pine sawdust and sodium hydroxide solution is 1:8; in step b, the solid-liquid ratio of rosin and the extraction solution is 1:2, and the addition amount of the sulfuric acid solution is 0.5% of the total weight of rosin and the extraction solution; in step c, the mass ratio of the mixed solution and anhydrous ethanol is 1:2.

[0025] Among them, the preparation method of the biochar main material includes the following steps: Step A: Raw material pretreatment. Select peony and straw as raw materials, crush them to 20 mesh, soak them in a phosphoric acid solution with a mass fraction of 3% for 6 h, then wash them with water until neutral and dry them to obtain a treated material; Step B: Carbonization and calcination. Place the treated material in a carbonization furnace, introduce nitrogen for protection, heat it at a heating rate of 5 °C / min to 450 °C, keep it warm for 1 h, then cool it to room temperature, and then crush it through a 100-mesh sieve after crushing by a crusher to obtain biochar raw materials; Step C: Mix the biochar raw materials with a hydrochloric acid solution with a mass fraction of 5% at a solid-liquid ratio of 1:5, stir at a speed of 100 r / min, stir for 1 h, then wash and dry to obtain the biochar main material.

[0026] Among them, the binder is prepared by mixing a water-based binder, reinforcing fibers, and a plasticizer in a mass ratio of 5:3:1. Among them, the water-based binder selects polyvinyl alcohol, the reinforcing fibers select wood fibers with a fiber length of 1 mm, and the plasticizer selects glycerol.

[0027] Example 2, a peony straw biochar composite material with a removal effect on hexavalent chromium in water, includes the following raw materials in parts by weight: 80 parts of biochar main material, 20 parts of the first auxiliary material, 10 parts of the second auxiliary material, 10 parts of the binder, and 6 parts of the third auxiliary material; The preparation method includes the following steps: S1: Weigh the biochar main material, the first auxiliary material, the second auxiliary material, and the third auxiliary material as needed and mix them to obtain a mixed material; S2: Put the mixed material into a mixer, then add the binder, and stir at 300 r / min for 60 min to obtain a slurry; S3: Inject the slurry into a mold, dry and cure it at a pressure of 30 MPa and a temperature of 100 °C for 8 h, then cool it to room temperature, and demold it to obtain a peony straw biochar composite material with a removal effect on hexavalent chromium in water.

[0028] Among them, the preparation method of the first auxiliary material includes the following steps: Step 1: Select orange peel as the raw material, dry and crush it to 50 mesh, then add it to a stirring tank, add deionized water and saccharifying enzyme, stir at 100 r / min for 2 h, then transfer it to a fermentation tank, ferment at 45 °C for 7 d, and then filter out impurities to obtain the fermentation broth; Step 2: Select clay particles with a particle size of 50 mesh as the raw material, add them to the fermentation broth and soak for 48 h, then dry at 120 °C to obtain dry particles; Step 3: Transfer the dry particles to a muffle furnace, heat up to 600 °C at a heating rate of 5 °C / min, calcine for 4 h and then cool to room temperature, then crush through a crusher and pass through a 200-mesh sieve to obtain the first auxiliary material.

[0029] Among them, in Step 1, the mass ratio of orange peel to deionized water is 1:10, and the saccharifying enzyme accounts for 0.5% of the weight of the orange peel. In Step 2, the mass ratio of clay particles to the fermentation broth is 1:5.

[0030] Among them, the preparation method of the second auxiliary material includes the following steps: Step 1: Select waste ceramic material as the raw material, wash, dry and crush it to 100 mesh, then add it to a hydrochloric acid solution with a mass fraction of 15% and soak for 4 h, then wash with water until neutral and dry to obtain the first ceramic powder; Step 2: Mix the ceramic powder and ferrous sulfate solution at a solid-liquid ratio of 1:5 and add them to a stirring kettle, stir at 400 r / min for 3 h, then add sodium hydroxide to adjust the pH to 11, and take the precipitate after centrifugal filtration, which is the second ceramic powder; Step 3: Dry the second ceramic powder at 150 °C, then transfer it to a rotary kiln, heat up to 500 °C at a heating rate of 8 °C / min, calcine for 2 h and then cool to room temperature, then crush through a crusher and pass through a 400-mesh sieve to obtain the second auxiliary material.

[0031] Among them, in Step 1, the solid-liquid ratio of waste ceramic material to hydrochloric acid solution is 1:10. In Step 2, the concentration of ferrous sulfate solution is 2 mol / L. In Step 3, the rotation speed of the rotary kiln is 10 r / min.

[0032] Among them, the preparation method of the third auxiliary material includes the following steps: Step a: Select pine sawdust as the raw material, mix it with a sodium hydroxide solution with a mass fraction of 10%, stir at 100 °C and 500 r / min for 4 h, filter out the solid matter to obtain the extract; Step b: Select rosin as the raw material and crush it to 100 mesh. Mix it with the extraction solution, then add a sulfuric acid solution with a mass fraction of 5% to adjust the pH to 4. Then stir and react at 80 °C and 50 r / min for 2 h to obtain a mixed solution. Step c: Cool the mixed solution to room temperature, then add absolute ethanol and let it stand for 4 h. After filtration, take the precipitate and put it into a drying oven to dry at 80 °C. Then crush it to 5 mm with a crusher to obtain the third auxiliary material.

[0033] Among them, in step a, the solid-liquid ratio of pine sawdust and sodium hydroxide solution is 1:12. In step b, the solid-liquid ratio of rosin and the extraction solution is 1:4, and the addition amount of the sulfuric acid solution is 2% of the total weight of rosin and the extraction solution. In step c, the mass ratio of the mixed solution and absolute ethanol is 1:4.

[0034] Among them, the preparation method of the biochar main material includes the following steps: Step A: Raw material pretreatment. Select peony and straw as raw materials, crush them to 50 mesh, soak them in a phosphoric acid solution with a mass fraction of 10% for 12 h, then wash them with water until neutral and dry them to obtain the treated material. Step B: Carbonization and calcination. Place the treated material in a carbonization furnace, introduce nitrogen for protection, heat it at a heating rate of 10 °C / min to 650 °C, keep it warm for 3 h and then cool it to room temperature. Then crush it with a crusher and pass it through a 300-mesh sieve to obtain the biochar raw material. Step C: Mix the biochar raw material and a hydrochloric acid solution with a mass fraction of 15% at a solid-liquid ratio of 1:10, stir at a stirring speed of 300 r / min, stir for 2 h, then wash and dry it to obtain the biochar main material.

[0035] Among them, the binder is prepared by mixing an aqueous binder, reinforcing fibers and a plasticizer in a mass ratio of 5:3:1. Among them, the aqueous binder selects starch glue, the reinforcing fibers select wood fibers with a fiber length of 5 mm, and the plasticizer selects dibutyl phthalate.

[0036] Example 3, a peony straw biochar composite material with a removal effect on hexavalent chromium in water bodies, includes the following raw materials in parts by weight: 70 parts of biochar main material, 15 parts of the first auxiliary material, 8 parts of the second auxiliary material, 8 parts of the binder, and 4 parts of the third auxiliary material; The preparation method includes the following steps: S1: Weigh the biochar main material, the first auxiliary material, the second auxiliary material, and the third auxiliary material as needed and mix them to obtain a mixed material; S2: Put the mixed material into a blender, then add the binder, and stir at 200 r / min for 45 min to obtain a slurry; S3: Inject the slurry into a mold, dry and cure it at a pressure of 20 MPa and a temperature of 80 °C for 6 h, then cool it to room temperature and demold it to obtain a peony straw biochar composite material with a removal effect on hexavalent chromium in water bodies.

[0037] Among them, the preparation method of the first auxiliary material includes the following steps: Step 1: Select orange peel as the raw material, dry it and crush it to 40 mesh, then add it to a stirring tank, add deionized water and saccharifying enzyme, stir at 80 r / min for 1.5 h, then transfer it to a fermentation tank, ferment at 40 °C for 6 d, and then filter out impurities to obtain a fermentation broth; Step 2: Select clay particles with a particle size of 40 mesh as the raw material, add them to the fermentation broth and soak for 36 h, then dry at 100 °C to obtain dry particles; Step 3: Transfer the dry particles to a muffle furnace, heat them up to 500 °C at a heating rate of 3 °C / min, calcine for 3 h and then cool to room temperature, then crush them through a crusher and pass through a 150-mesh sieve to obtain the first auxiliary material.

[0038] Among them, in Step 1, the mass ratio of orange peel to deionized water is 1:8, and the saccharifying enzyme accounts for 0.3% of the weight of the orange peel. In Step 2, the mass ratio of clay particles to the fermentation broth is 1:4.

[0039] Among them, the preparation method of the second auxiliary material includes the following steps: Step 1: Select waste ceramic materials as the raw material, wash, dry and crush them to 80 mesh, then add them to a hydrochloric acid solution with a mass fraction of 10% and soak for 3 h, then wash with water until neutral and dry to obtain the first ceramic powder; Step 2: Mix the ceramic powder and ferrous sulfate solution at a solid-liquid ratio of 1:4 and add them to a stirring kettle, stir at 300 r / min for 2 h, then add sodium hydroxide to adjust the pH to 10, and take the precipitate after centrifugal filtration, which is the second ceramic powder; Step 3: Dry the second ceramic powder at 120 °C, then transfer it to a rotary kiln, heat it up to 450 °C at a heating rate of 6 °C / min, calcine for 1.5 h and then cool to room temperature, then crush it through a crusher and pass through a 300-mesh sieve to obtain the second auxiliary material.

[0040] Among them, in Step 1, the solid-liquid ratio of waste ceramic materials to hydrochloric acid solution is 1:8. In Step 2, the concentration of ferrous sulfate solution is 1.5 mol / L. In Step 3, the rotation speed of the rotary kiln is 8 r / min.

[0041] Among them, the preparation method of the third auxiliary material includes the following steps: Step a: Select pine sawdust as the raw material, mix it with a sodium hydroxide solution with a mass fraction of 8%, stir at 95 °C and 400 r / min for 3 h, filter out the solid matter to obtain an extract; Step b: Select rosin as the raw material and crush it to 80 mesh. Mix it with the extraction solution, then add a sulfuric acid solution with a mass fraction of 3% to adjust the pH to 3. Then stir and react at 70 °C and 40 r / min for 1.5 h to obtain a mixed solution; Step c: Cool the mixed solution to room temperature, then add absolute ethanol and let it stand for 3 h. After filtration, take the precipitate and put it into a drying oven to dry at 60 °C. Then crush it to 3 mm with a crusher to obtain the third auxiliary material.

[0042] Among them, in step a, the solid-liquid ratio of pine sawdust to sodium hydroxide solution is 1:10. In step b, the solid-liquid ratio of rosin to the extraction solution is 1:3, and the addition amount of the sulfuric acid solution is 1% of the total weight of rosin and the extraction solution. In step c, the mass ratio of the mixed solution to absolute ethanol is 1:3.

[0043] Among them, the preparation method of the biochar main material includes the following steps: Step A: Raw material pretreatment. Select peony and straw as raw materials, crush them to 40 mesh, soak them in a phosphoric acid solution with a mass fraction of 7% for 10 h, then wash them with water until neutral and dry them to obtain the treated material; Step B: Carbonization and calcination. Place the treated material in a carbonization furnace, introduce nitrogen for protection, heat it at a heating rate of 8 °C / min to 500 °C, keep it warm for 2 h and then cool it to room temperature. Then crush it with a crusher and pass it through a 200-mesh sieve to obtain the biochar raw material; Step C: Mix the biochar raw material with a hydrochloric acid solution with a mass fraction of 5-15% according to a solid-liquid ratio of 1:8, stir at a speed of 200 r / min, stir for 1.5 h, then wash and dry it to obtain the biochar main material.

[0044] Among them, the binder is prepared by mixing an aqueous binder, reinforcing fibers, and a plasticizer in a mass ratio of 5:3:1. Among them, the aqueous binder selects sodium carboxymethyl cellulose, the reinforcing fibers select wood fibers with a fiber length of 3 mm, and the plasticizer selects glycerol.

[0045] Comparative Example 1. The difference between this comparative example and Examples 1-3 is that: in the preparation process of the peony straw biochar composite material with a removal effect on hexavalent chromium in water in this comparative example, the first auxiliary material is not added.

[0046] Comparative Example 2. The difference between this comparative example and Examples 1-3 is that: in the preparation process of the peony straw biochar composite material with a removal effect on hexavalent chromium in water in this comparative example, the second auxiliary material is not added.

[0047] Comparative Example 2. The difference between this comparative example and Examples 1-3 is that: in the preparation process of the peony straw biochar composite material with a removal effect on hexavalent chromium in water in this comparative example, the third auxiliary material is not added.

[0048] Perform performance tests on the nano-palladium or platinum carbon monoxide combustion promoters prepared in Examples 1-3 and Comparative Examples 1-3, and record the test data in the following table: Test method: Static adsorption removal rate: Take 100 mL of hexavalent chromium-containing wastewater with a concentration of 200 mg / L, add 0.2 g of the sample, shake for 24 hours until equilibrium, and measure the remaining concentration to calculate the removal rate; Equilibrium adsorption capacity: Based on the static adsorption experiment data, calculate the equilibrium adsorption capacity (unit: mg / g) according to the formula Q e =(C0 - C e )×V / m; Recycling and regeneration performance: Use 5% hydrochloric acid + 5% sodium hydroxide for alternating regeneration, and test the retention rate of the removal rate after 5 cycles.

[0049] By comparing the test data of Examples 1-3 in the table, it is obvious that they are superior to the test data of Comparative Examples 1-3 and conventional activated carbon. The removal rate and adsorption capacity of Comparative Example 1 decreased significantly because the "carbon-clay" composite structure formed by modifying clay with orange peel fermentation broth as the first auxiliary material can provide additional ion exchange sites and surface roughness. Without it, the material lacks this specific adsorption ability, resulting in a reduced capture efficiency for hexavalent chromium. The performance of Comparative Example 2 decreased because the iron-modified ceramic material of the second auxiliary material can reduce hexavalent chromium to trivalent chromium through redox reactions, promoting precipitation and fixation. Without it, it only relies on physical adsorption, cannot break through the capacity limit of a single adsorption mechanism, and the treatment ability for high-concentration wastewater is weakened. Comparative Example 3 showed medium performance because the pine sawdust and rosin composite of the third auxiliary material contains chelating groups such as phenolic hydroxyl and carboxyl groups, which can specifically bind hexavalent chromium and reduce the interference of competitive anions. Without it, the adaptability of the material to complex water quality decreases, but the basic adsorption capacity is still supported by biochar and other auxiliary materials. The indicators of Comparative Example 4 are the lowest because conventional activated carbon only relies on physical pore adsorption and lacks the chemical modification functional groups of biochar, the redox effect of iron-based active phases, and the synergistic effect of organic auxiliary materials in this scheme, resulting in insufficient removal efficiency and cycle stability; Secondly, in the recycling and regeneration performance test, the removal rate of Examples 1-3 remained above 82% after cycling. Thanks to the structural stability of the composite system, the three-dimensional network formed by the binder fixes the functional components, avoiding the loss of active sites during the regeneration process. The iron-based active phase of the second auxiliary material can restore part of its redox ability through acid-base adjustment, and the organic components of the third auxiliary material maintain the activity of functional groups under mild regeneration conditions. However, for Comparative Examples 1-3 and conventional activated carbon, due to the lack of key synergistic mechanisms, site failure or structural damage is likely to occur during regeneration, resulting in faster performance decay.

[0050] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0051] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A peony straw biochar composite material with a removal effect on hexavalent chromium in water bodies, characterized in that, It includes the following raw materials in parts by weight: 60-80 parts of main biochar material, 10-20 parts of first auxiliary material, 5-10 parts of second auxiliary material, 5-10 parts of binder, and 2-6 parts of third auxiliary material; Preparation method It includes the following steps: S1: Weigh the main biochar material, first auxiliary material, second auxiliary material, and third auxiliary material as needed and mix them to obtain a mixture; S2: Put the mixture into a blender, then add the binder, and stir at 100-300 r / min for 30-60 min to obtain a slurry; S3: Inject the slurry into a mold, dry and cure it at a pressure of 10-30 MPa and a temperature of 60-100 °C for 4-8 h, then cool it to room temperature and demold to obtain a peony straw biochar composite material with the effect of removing hexavalent chromium in water; The preparation method of the first auxiliary material includes the following steps: Step 1: Select orange peel as the raw material, dry it and crush it to 20-50 mesh, then add it to a stirring tank, add deionized water and saccharifying enzyme, stir at 50-100 r / min for 1-2 h, then transfer it to a fermentation tank, and ferment at 30-45 °C for 5-7 d, and then filter out impurities to obtain a fermentation broth; Step 2: Select clay particles with a particle size of 20-50 mesh as the raw material, add them to the fermentation broth and soak for 24-48 h, and then dry at 80-120 °C to obtain dry particles; Step 3: Transfer the dry particles to a muffle furnace, heat them at a heating rate of 2-5 °C / min to 400-600 °C, calcine for 2-4 h and then cool to room temperature, and then crush them through a crusher and pass through a 100-200 mesh sieve to obtain the first auxiliary material.

2. The paeonia lactiflora pall. straw biochar composite material with a removal effect on hexavalent chromium in water bodies according to claim 1, wherein In the said Step 1, the mass ratio of orange peel to deionized water is 1:(5-10), and the saccharifying enzyme accounts for 0.1-0.5% of the weight of orange peel. In Step 2, the mass ratio of clay particles to fermentation broth is 1:(3-5).

3. The paeonia lactiflora pall. straw biochar composite material with the effect of removing hexavalent chromium from water bodies according to claim 1, wherein The preparation method of the second auxiliary material includes the following steps: Step 1: Select waste ceramic material as the raw material, wash, dry and crush it to 50-100 mesh, then add it to a hydrochloric acid solution with a mass fraction of 5-15% and soak for 2-4 h, then wash it with water until neutral and dry it to obtain the first ceramic powder; Step 2: Mix the ceramic powder and ferrous sulfate solution according to a solid-liquid ratio of 1:(3-5) and add them to a stirring kettle, stir at 200-400 r / min for 1-3 h, then add sodium hydroxide to adjust the pH to 9-11, and take the precipitate after centrifugal filtration, which is the second ceramic powder; Step 3: Dry the second ceramic powder at 100-150 °C, then transfer it to a rotary kiln, heat it at a heating rate of 3-8 °C / min to 350-500 °C, calcine for 1-2 h and then cool to room temperature, and then crush it through a crusher and pass through a 200-400 mesh sieve to obtain the second auxiliary material.

4. The paeonia lactiflora pall. straw biochar composite material with the effect of removing hexavalent chromium in water bodies according to claim 3, wherein, In Step 1, the solid-liquid ratio of the waste ceramic material to the hydrochloric acid solution is 1:(5-10). In Step 2, the concentration of the ferrous sulfate solution is 0.5-2 mol / L. In Step 3, the rotation speed of the rotary kiln is 5-10 r / min.

5. The peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies according to claim 1, wherein, The preparation method of the third auxiliary material includes the following steps: Step a: Select pine sawdust as the raw material, add it to a sodium hydroxide solution with a mass fraction of 5 - 10%, mix, and stir at 90 - 100 °C and 300 - 500 r / min for 2 - 4 h. After filtering to remove the solid matter, an extract is obtained; Step b: Select rosin as the raw material and crush it to 50 - 100 mesh. Mix it with the extract, then add a sulfuric acid solution with a mass fraction of 1 - 5% to adjust the pH to 2 - 4, and then stir and react at 60 - 80 °C and 20 - 50 r / min for 1 - 2 h to obtain a mixed solution; Step c: Cool the mixed solution to room temperature, then add anhydrous ethanol and let it stand for 2 - 4 h. After filtering, take the precipitate and add it to a drying oven, dry it at 50 - 80 °C, and then crush it to 1 - 5 mm by a crusher to obtain the third auxiliary material.

6. The paeonia lactiflora pall. straw biochar composite material with a removal effect on hexavalent chromium in water bodies according to claim 5, characterized in that, In step a, the solid - liquid ratio of pine sawdust to sodium hydroxide solution is 1:(8 - 12). In step b, the solid - liquid ratio of rosin to the extract is 1:(2 - 4), and the addition amount of the sulfuric acid solution is 0.5 - 2% of the total weight of rosin and the extract. In step c, the mass ratio of the mixed solution to anhydrous ethanol is 1:(2 - 4).

7. The peony straw biochar composite material with the effect of removing hexavalent chromium in water bodies according to claim 1, wherein The preparation method of the biochar main material includes the following steps: Step A: Raw material pretreatment. Select peony and straw as raw materials, crush them to 20 - 50 mesh, soak them in a phosphoric acid solution with a mass fraction of 3 - 10% for 6 - 12 h, then wash them with water until neutral and dry to obtain the treated material; Step B: Carbonization and calcination. Place the treated material in a carbonization furnace, introduce nitrogen for protection, heat it at a heating rate of 5 - 10 °C / min to 450 - 650 °C, keep it warm for 1 - 3 h, then cool it to room temperature, and then crush it and pass it through a 100 - 300 - mesh sieve to obtain the biochar raw material; Step C: Mix the biochar raw material with a hydrochloric acid solution with a mass fraction of 5 - 15% at a solid - liquid ratio of 1:(5 - 10), stir at a speed of 100 - 300 r / min, stir for 1 - 2 h, then wash and dry to obtain the biochar main material.

8. A peony straw biochar composite material with a removal effect on hexavalent chromium in water bodies according to claim 1, characterized in that The binder is prepared by mixing an aqueous binder, reinforcing fibers, and a plasticizer in a mass ratio of 5:3:1, where the aqueous binder can be at least one of polyvinyl alcohol, sodium carboxymethyl cellulose, and starch glue.

9. A Paeonia lactiflora Pall. straw biochar composite material with a removal effect on hexavalent chromium in water bodies, characterized in that, The reinforcing fibers can be at least one of wood fibers or glass fibers with a fiber length of 1 - 5 mm.

10. A peony straw biochar composite material with a removal effect on hexavalent chromium in water bodies, characterized in that, The plasticizer can be at least one of glycerol or dibutyl phthalate.

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