Method for synthesizing phosphorus trapping material from biomass waste through Fenton oxidation and acid hydrothermal synthesis and product of phosphorus trapping material

Abstract

The invention discloses a method for synthesizing a phosphorus trapping material from biomass waste through Fenton oxidation and acid hydrothermal synthesis and a product thereof, and belongs to the technical field of waste resource.The method comprises the following steps that biomass waste is crushed and dried, then a Fenton reagent is added, the pH of a solution is adjusted to be acidic, and standing is conducted; then carrying out hydrothermal reaction, and then sequentially separating, washing and drying to obtain hydrothermal carbon; and immersing the hydrothermal carbon into a solution containing a phosphorus source, and carrying out centrifugal separation and drying to prepare the phosphorus trapping material. Compared with other common hydrothermal carbon, the hydrothermal carbon prepared by the method disclosed by the invention has the advantage that the phosphorus adsorption capacity is greatly improved. And when being used as a phosphorus slow-release fertilizer, the compound fertilizer has longer phosphate release capacity and better soil improvement effect, and can further promote the growth of plants.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste resource utilization, and particularly relates to a method for synthesizing a phosphorus capture material by Fenton oxidation of biomass waste in cooperation with acid hydrothermal treatment and its product. Background Art

[0002] Phosphorus is a nutrient essential for modern agriculture and food production. Since the last century, the world's population has been growing continuously, and the demand for phosphorus-based fertilizers has also been increasing accordingly. Nowadays, the production of phosphate fertilizers mainly relies on extracting phosphorus from natural deposits of phosphate minerals (apatite). However, the non-renewability of phosphate rock resources will lead to the depletion of a large amount of phosphate rock resources used as phosphate fertilizers in the next few decades, affecting the cost of agricultural products and threatening global food supply. The scarcity of phosphate rock has shifted people's attention to phosphorus recovery and reuse.

[0003] China is rich in waste biomass resources. For example, the annual output of crop straws is as high as about 700 million tons, the amount of food waste is about 100 million to 150 million tons, and the amount of forestry waste also reaches about 37 million tons. However, the current utilization rate of these waste biomass is not ideal and far from sufficient, which not only causes great waste of precious biomass resources but also may pollute the environment. Therefore, considering the resource attributes of phosphorus and waste biomass comprehensively, developing a technology that can effectively use these waste biomass as raw materials to manufacture phosphorus adsorption materials will have great application prospects and value.

[0004] Literature research found that hydrochar synthesized by hydrothermal carbonization of waste biomass has been regarded as one of the promising phosphorus adsorbents. Hydrochar has a certain pore structure, and its surface has aromatic groups and oxygen-containing functional groups, making it have an effective binding force for pollutants. Acid hydrothermal treatment or oxidation modification of raw biomass with hydrogen peroxide as an oxidant will increase the formation of oxygen-containing functional groups, and at the same time increase the specific surface area and mesopore area, thereby improving the adsorption capacity. However, the increase in surface alkalinity and negative charge of hydrochar will also limit its adsorption efficiency for anionic pollutants such as phosphate.

[0005] Therefore, there is an urgent need to provide a hydrochar-based phosphorus capture material that can improve phosphorus adsorption efficiency and its preparation method. Summary of the Invention

[0006] In view of the above technical problems, the present invention provides a method for synthesizing a phosphorus capture material by Fenton oxidation of biomass waste in combination with acid hydrothermal treatment and its product. Specifically, the present invention uses biomass waste as a raw material, adopts Fenton oxidation in combination with acid hydrothermal synthesis of a phosphorus capture material, and uses it as a phosphorus slow-release fertilizer. This combined method can effectively utilize biological waste, prepare hydrochar with high phosphorus adsorption efficiency at relatively low treatment costs, avoid environmental pollution, and at the same time, when applied as a phosphorus slow-release fertilizer, it can increase the soil nutrient content and promote the growth of crops.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention:

[0009] A method for synthesizing a phosphorus capture material by Fenton oxidation of biomass waste in combination with acid hydrothermal treatment, comprising the following steps:

[0010] Crush and dry the biomass waste, then add Fenton's reagent, adjust the pH of the solution to be acidic, and let it stand; then carry out hydrothermal reaction, and then carry out separation, washing and drying in sequence to obtain hydrochar;

[0011] Immerse the hydrochar in a solution containing a phosphorus source, and then carry out centrifugal separation and drying to prepare the phosphorus capture material.

[0012] Optionally, the biological waste includes plant straw or food waste.

[0013] Optionally, the dosage ratio of the biomass waste to Fenton's reagent is 1 g∶(5 - 20 mL).

[0014] Furthermore, the Fenton's reagent is composed of 5 mL - 10 mL of 30% hydrogen peroxide solution and 0.0025 M - 0.01 M ferrous sulfate.

[0015] Optionally, the pH is 0 - 4.

[0016] Optionally, the standing time is 1 - 6 h.

[0017] Optionally, the temperature during the hydrothermal reaction is 180 - 220 °C, and the time is 3 - 6 h.

[0018] Optionally, the dosage ratio of the hydrochar to the solution containing a phosphorus source is (0.1 - 0.2) g∶(40 - 100) ml; wherein, the concentration of the solution containing a phosphorus source is 50 - 200 mg / L.

[0019] Further, the phosphorus source includes inorganic phosphorus and organic phosphorus; the inorganic phosphorus includes potassium dihydrogen phosphate and dipotassium hydrogen phosphate; the organic phosphorus includes phytate phosphorus and its downstream products (a series of compounds derived from phytate phosphorus through chemical or biological transformation).

[0020] Optionally, the time during the immersion process is 1440 min.

[0021] The second technical solution of the present invention:

[0022] A phosphorus capture material is prepared by the above preparation method.

[0023] The third technical solution of the present invention:

[0024] The application of the above phosphorus capture material as a slow-release phosphorus fertilizer.

[0025] The fourth technical solution of the present invention:

[0026] A slow-release phosphorus fertilizer, the raw materials of which include the above phosphorus capture material.

[0027] The fifth technical solution of the present invention:

[0028] The application of the above slow-release phosphorus fertilizer in promoting plant growth.

[0029] Optionally, the application rate of the slow-release phosphorus fertilizer is (1 - 4 g) / 1000 g of soil.

[0030] Optionally, the plants include at least one of soybean, pakchoi and corn.

[0031] Compared with the prior art, the present invention has the following advantages and technical effects:

[0032] The present invention combines Fenton pretreatment and acidic hydrothermal treatment, and hydrothermally carbonizes biomass waste into hydrochar rich in functional groups by creating a strongly oxidizing and acidic hydrothermal environment, which is beneficial to the loading of metal cation iron through C-O-Fe chemical bonds. The iron-loaded hydrochar developed in this way has excellent phosphorus adsorption capacity. Moreover, the advantages of the present invention are not only reflected in the cleanliness of the raw material biomass waste, but also by combining acidic hydrothermal treatment and Fenton pretreatment in one step, it can effectively reduce energy consumption and is convenient to operate.

[0033] The hydrochar prepared by the method of the present invention has a greatly improved phosphorus adsorption capacity compared with other ordinary hydrochars. Moreover, when used as a slow-release phosphorus fertilizer, it has a longer phosphate release capacity and a better soil improvement effect, further promoting plant growth. Therefore, the method for synthesizing the phosphorus capture material of the present invention has the characteristics of cleanliness, high efficiency and convenience.

[0034] Therefore, the method for synthesizing a phosphorus capture material by Fenton oxidation in coordination with acid hydrothermal treatment of biomass waste disclosed in the present invention has the following advantages:

[0035] 1. No secondary pollution is generated during the hydrothermal process of biomass waste;

[0036] 2. The hydrothermal treatment has high efficiency, milder conditions than pyrolysis, and saves resources;

[0037] 3. There are significantly more adsorption sites and a high specific surface area in the hydrochar, the solid-phase product after hydrothermal treatment, which can adsorb phosphorus or other pollutants;

[0038] 4. Hydrochar can not only be used as a phosphate adsorbent, but also as a phosphorus slow-release fertilizer, a clean fuel, and a carbon-based soil remediation agent;

[0039] 5. The phosphorus slow-release fertilizer prepared by the present invention has better soil improvement effects and plant growth promotion effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0041] Figure 1 is the process flow diagram of the phosphorus capture material prepared in the embodiment of the present invention;

[0042] Figure 2 is the phosphorus adsorption capacity curve graph of the hydrochar prepared in Example 1 of the present invention and the straw control group;

[0043] Figure 3 is the phosphorus adsorption capacity curve graph of the hydrochar prepared in Example 2 of the present invention and the food waste control group. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation to the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0045] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0046] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0047] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0048] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0049] An embodiment of this invention discloses a method for the Fenton oxidation of biomass waste in cooperation with acid hydrothermal synthesis of a phosphorus capture material, comprising the following steps:

[0050] First, the biomass waste is crushed and dried, then placed into a hydrothermal reaction kettle, Fenton reagent is added, and after the solution is adjusted to be acidic and left standing, a hydrothermal carbonization reaction is carried out; after the reaction, the mixture is subjected to solid-liquid separation, and the solid-phase product is hydrochar. Further, after the hydrochar is washed and dried, a phosphorus capture material (hydrochar) is prepared.

[0051] In some alternative embodiments, the biomass waste is food waste or plant straw; the plant straw can be corn straw.

[0052] In some alternative embodiments, the ratio of the biomass waste to the Fenton reagent is 1 g∶(5 - 20 mL).

[0053] In some alternative embodiments, the Fenton reagent consists of 5 mL - 10 mL of 30% (mass concentration) hydrogen peroxide solution and 0.0025 M - 0.01 M (i.e., the addition amount of ferrous sulfate is based on the ferrous sulfate concentration in the final Fenton reagent being 0.0025 M - 0.01 M) ferrous sulfate.

[0054] In some alternative embodiments, adjusting the solution to be acidic specifically means adjusting the pH of the solution to 0 - 4 using an inorganic acid, and common inorganic acids such as hydrochloric acid or sulfuric acid can be used for adjustment.

[0055] In some alternative embodiments, the standing time is 1 to 6 h; the hydrothermal carbonization reaction temperature is 180 to 220 °C, and the hydrothermal carbonization reaction time is 3 to 6 h.

[0056] An embodiment of the present invention also discloses a phosphorus capture material prepared by the above preparation method.

[0057] In addition, an embodiment of the present invention also discloses the use of the above phosphorus capture material for preparing a phosphorus slow-release fertilizer.

[0058] In some alternative embodiments, the phosphorus slow-release fertilizer includes a phosphorus capture material and a phosphorus-containing substance.

[0059] In some alternative embodiments, the phosphorus-containing substance includes inorganic phosphorus and organic phosphorus, wherein the inorganic phosphorus includes potassium dihydrogen phosphate and dipotassium hydrogen phosphate; the organic phosphorus includes phytic acid phosphorus and its downstream products; the adsorption performance of the phosphorus capture material is measured as the adsorbed solution.

[0060] The present invention also discloses the application of the above phosphorus slow-release fertilizer in promoting plant growth.

[0061] In some alternative embodiments, the plants include soybeans, pakchoi, and corn.

[0062] In some alternative embodiments, the application rate of the phosphorus slow-release fertilizer is (1 to 4 g) / 1000 g of soil.

[0063] In the present invention, "room temperature" refers to 20 - 30 °C unless otherwise specified.

[0064] In the present invention, "parts" refers to parts by mass unless otherwise specified.

[0065] All raw materials used in the present invention are obtained by purchasing on the market.

[0066] The technical solution of the present invention is further described below through examples.

[0067] Example 1

[0068] 1 g of crushed and dried corn straw was added to a polytetrafluoroethylene-lined inner container, and Fenton's reagent (composed of 10 mL of 30% hydrogen peroxide solution and 0.0025 M ferrous sulfate, where the addition amount of ferrous sulfate was based on the final concentration of ferrous sulfate in Fenton's reagent being 0.0025 M) was added. The pH value was adjusted to 1 with concentrated hydrochloric acid; after standing for 1 h, the inner container was placed in a reaction kettle and kept at 190 °C for 3 h for reaction; after the reaction was completed, it was naturally cooled to room temperature, vacuum filtered with a 0.45 μm filter membrane, washed several times with clear water, and the solid was taken out and dried at 80 °C to obtain hydrochar.

[0069] Straw control group: Ferrous sulfate and hydrogen peroxide (i.e., Fenton's reagent) were not added, and other operating conditions were the same.

[0070] Take 0.1 g of the hydrochar prepared in Example 1 and the straw control group and add them to 40 mL of potassium dihydrogen phosphate solution with a concentration of 50 mg / L (calculated as phosphorus) respectively. The adsorption period is 24 hours. Measure the phosphorus content in the adsorbed solution before and after adsorption at 5 min, 30 min, 60 min, 240 min, 480 min, and 1440 min, as Figure 2 shown. The test standard for the phosphorus content in the solution: GB11893-89, using potassium persulfate digestion. Centrifuge to separate the solid, which is the phosphorus capture material. Dry it to a constant weight in an oven at 60 °C and store it at room temperature for further experiments.

[0071] The pot experiment was carried out under greenhouse conditions. Thoroughly mix 1000 g of soil with 4 g of phosphorus capture material (the hydrochar obtained after 1440 min of adsorption by the hydrochar prepared in Example 1, with a phosphorus content of 10.5 mg / g), and at the same time measure the phosphorus content in the original soil. Subsequently, sow soybean seeds at a depth of 1.5 cm on top of each pot of soil. After 45 days of cultivation, harvest the plant buds and roots, and measure the dry weight and phosphorus content of the whole plant. At the same time, collect the soil, dry it and pass it through a 10-mesh sieve, and measure the available phosphorus and organic matter content in the soil. The blank control group of the pot experiment did not add phosphorus capture material, and the other operating conditions were the same. The effect data are shown in Table 1.

[0072] Table 1 Application of straw hydrochar phosphorus slow-release fertilizer

[0073]

[0074] Example 2

[0075] Add 1 g of crushed and dried food waste to the PTFE-lined container, add Fenton's reagent (consisting of 10 mL of 30% hydrogen peroxide solution and 0.0025 M ferrous sulfate, where the addition amount of ferrous sulfate is based on the final concentration of ferrous sulfate in Fenton's reagent being 0.0025 M), and adjust the pH value to 1 with concentrated hydrochloric acid. After standing for 1 h, place the lined container in a reaction kettle and keep it at 190 °C for 3 h for reaction; after the reaction is completed, naturally cool it to room temperature, vacuum filter it with a 0.45 μm filter membrane, and then wash it several times with clear water. Take out the solid and dry it at 80 °C to obtain hydrochar.

[0076] The food waste control group did not add ferrous sulfate and hydrogen peroxide, and the other operating conditions were the same.

[0077] Take 0.1 g of the hydrochar prepared in Example 2 and the food waste control group and add them to 40 mL of potassium dihydrogen phosphate solution with a concentration of 50 mg / L (calculated as phosphorus) respectively. The adsorption period is 24 hours. Measure the phosphorus content in the adsorbed solution before and after adsorption at 5 min, 30 min, 60 min, 240 min, 480 min, and 1440 min, asFigure 3 As shown. The test standard for phosphorus content in the solution: GB11893-89, and potassium persulfate digestion is adopted.

[0078] The pot experiment was carried out under greenhouse conditions. 1000 g of soil was thoroughly mixed with 4 g of phosphorus capture material (the phosphorus capture material obtained after the hydrochar prepared in Example 2 was adsorbed for 1440 min, and the phosphorus content was 13.0 mg / g). Subsequently, soybean seeds were sown at a depth of 1.5 cm on top of each pot of soil. After 45 days of cultivation, the plant buds and roots were harvested, and the total phosphorus content of the whole plant was measured. At the same time, the soil was collected, air-dried and passed through a 10-mesh sieve, and the available phosphorus and organic matter content of the soil were measured. The blank control group of the pot experiment did not add the phosphorus capture material, and the other operating conditions were the same. The effect data are shown in Table 2.

[0079] Table 2 Phosphorus capture material of food waste hydrochar

[0080]

[0081] As can be seen from Tables 1 and 2, after applying the phosphorus capture material as a slow-release phosphorus fertilizer to the soil, the phosphorus release rate of the slow-release phosphorus fertilizer is close to the phosphorus absorption rate of plants, and the matching degree is greater than 70% (matching degree = the difference in plant phosphorus content between the example and the blank control group in mg / (the available phosphorus content in the soil after cultivation in the example in mg - the initial total available phosphorus content in the soil of the example in mg)); and it has an obvious effect of promoting plant growth; the available phosphorus content in the soil increases, and the organic matter content increases, that is, the soil fertility increases. It is proved that the phosphorus capture material prepared by the present invention has good soil improvement and plant growth promotion effects when applied as a slow-release phosphorus fertilizer.

[0082] Figure 2 It is the phosphorus adsorption amount curve graph of the hydrochar prepared in Example 1 of the present invention and the straw control group; Figure 3 It is the phosphorus adsorption amount curve graph of the hydrochar prepared in Example 1 of the present invention and the food waste control group. From Figure 2 and Figure 3 it can be seen that the hydrochar derived from waste biomass by Fenton oxidation synergistic acid hydrothermal treatment has a higher phosphate adsorption amount than the hydrochar obtained by direct hydrothermal treatment of the raw material. Therefore, the Fenton oxidation synergistic acid hydrothermal treatment defined in the present invention enhances the phosphorus adsorption ability of the hydrochar derived from waste biomass.

[0083] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for synthesizing phosphorus capture materials by Fenton oxidation of biomass waste in synergistic acid hydrothermal synthesis, characterized in that: The following steps are involved: The biomass waste is crushed and dried, and then Fenton's reagent is added to adjust the pH of the solution to be acidic and allowed to stand; Then, a hydrothermal reaction is carried out, followed by separation, washing and drying in sequence to obtain hydrothermal charcoal; The hydrothermal carbon is immersed in a solution containing a phosphorus source, and then centrifuged and dried to prepare the phosphorus capture material.

2. The method for synthesizing phosphorus capture materials by Fenton oxidation of biomass waste in synergistic acid hydrothermal synthesis according to claim 1, characterized in that: The biological waste is selected from plant straw or kitchen waste.

3. The method for synthesizing phosphorus capture materials by Fenton oxidation of biomass waste in synergistic acid hydrothermal synthesis according to claim 1, characterized in that: The usage ratio of the biomass waste and the Fenton reagent is 1 g: (5-20) mL.

4. The method for synthesizing phosphorus capture materials by Fenton oxidation of biomass waste in synergistic acid hydrothermal synthesis according to claim 1, characterized in that: The pH is 0 to 4; and / or, The standing time is 1 to 6 hours.

5. The method for synthesizing phosphorus capture materials by Fenton oxidation of biomass waste in synergistic acid hydrothermal method according to claim 1, characterized in that: The conditions of the hydrothermal reaction are: temperature of 180-220° C. and time of 3-6 hours.

6. The method for synthesizing phosphorus capture materials by Fenton oxidation of biomass waste in synergistic acid hydrothermal synthesis according to claim 1, characterized in that: The usage ratio of the hydrothermal charcoal to the solution containing the phosphorus source is (0.1-0.2) g: (40-100) mL; wherein the concentration of the solution containing the phosphorus source is 50-200 mg / L; and / or, The control time during the immersion process is 1440 minutes.

7. A phosphorus capture material, characterized in that: The method is prepared by any one of claims 1 to 6.

8. Use of the phosphorus capture material according to claim 7 as a phosphorus slow-release fertilizer.

9. A slow-release phosphorus fertilizer, characterized in that: The raw material comprises the phosphorus capture material according to claim 7.

10. Use of the slow-release phosphorus fertilizer as claimed in claim 9 in promoting plant growth.

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