A method for resource utilization of rice husk ash

Abstract

This invention belongs to the field of agricultural waste resource utilization, and relates to a method for the resource utilization treatment of rice husk ash, comprising the following steps: S1: Mixing rice husk ash with a strong alkaline solution for alkaline extraction to obtain a first filtrate and filter residue. S2: Washing the filter residue to obtain a second filtrate. S3: Mixing the first and second filtrates and adding acid for acidification to obtain a reaction solution. S4: Using part of the filter residue as filter bed packing, the reaction solution is filtered through the packing to obtain preliminary silicon-rich activated carbon and filtrate. S5: Washing and drying the preliminary silicon-rich activated carbon to obtain silicon-rich activated carbon. S6: Mixing the filtrate with the remaining filter residue and filtering to obtain liquid silicon fertilizer. This invention's treatment method does not require high temperature and high pressure conditions, avoiding the high energy consumption problem of traditional rice husk ash silicon production processes. Furthermore, it does not generate any waste liquid or waste residue during the entire operation process, achieving clean production and possessing significant environmental advantages.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of agricultural waste resource utilization, and particularly relates to a resource utilization treatment method of rice husk ash. BACKGROUND

[0002] Rice husk ash (RHA) is a kind of agricultural waste resource rich in silicon dioxide, which is mainly derived from the residue after the combustion of rice husk in the rice processing process. Due to its wide source, low cost and high proportion of amorphous silicon dioxide, it has been widely studied in recent years for the preparation of silicon-based materials such as polycrystalline silicon, nano-silicon and silicon compounds.

[0003] In the prior art, the main methods for extracting silicon from rice husk ash include chemical method, physical method, biological method and other auxiliary means. Among them, the chemical method is more common, mainly including alkali fusion method and acid leaching method. The alkali fusion method needs to react the rice husk ash with strong alkali at a high temperature of 600-900℃ to generate sodium silicate, and then the silicon dioxide is precipitated by acidification with strong acid. The acid leaching method also needs to calcine the rice husk ash after acid washing at a high temperature of 500-700℃. Both of the above two chemical methods will produce a large amount of waste liquid and need to be treated at high temperature. The physical method mainly obtains silicon-based products through high-temperature treatment, which has high energy consumption. The biological method uses the metabolic products of fungi or bacteria to dissolve the silicon in the rice husk ash, and then the silicon is guided to deposit in a certain direction by biological molecules, but this method is still in the laboratory research stage and is not mature. Carbonthermal reduction method, sol-gel method and other methods are also used to extract high-purity silicon from rice husk ash, but often accompanied by more complex process and higher energy consumption requirements.

[0004] Therefore, the existing technology for extracting silicon from rice husk ash generally has the problems of producing a large amount of waste liquid, causing environmental pollution, and high energy consumption, and it is necessary to provide a more environmentally friendly and lower energy consumption method for extracting silicon from rice husk ash. SUMMARY

[0005] (I) Technical problem to be solved

[0006] In order to solve the problem that the method for extracting silicon from rice husk ash in the prior art generally produces a large amount of waste liquid, causes environmental pollution, and has high energy consumption, the present application provides a resource utilization treatment method of rice husk ash.

[0007] (II) Technical scheme

[0008] In order to achieve the above purpose, the main technical scheme adopted by the present application comprises:

[0009] The present application provides a resource utilization treatment method of rice husk ash, comprising the following steps:

[0010] S1: mixing rice husk ash with strong alkali solution, carrying out alkali extraction treatment, obtaining first filtrate and filter residue;

[0011] S2: washing the filter residue by water, obtaining second filtrate;

[0012] S3: mixing the first filtrate and the second filtrate, then adding acid solution, carrying out acidification treatment, obtaining reaction liquid;

[0013] S4: taking part of the filter residue as the filler of filter bed, making the reaction liquid pass through the filler for filtration treatment, obtaining preliminary silicon-rich activated carbon and filtrate;

[0014] S5: washing the preliminary silicon-rich activated carbon, drying to obtain silicon-rich activated carbon;

[0015] S6: mixing the filtrate with the remaining filter residue, removing the solid to obtain liquid silicon fertilizer.

[0016] The resource treatment method of rice husk ash as described above, preferably, in step S1, the molar ratio of silicon dioxide in the rice husk ash to hydroxyl in the strong alkali is 2:1-4:3, the time of alkali extraction treatment is ≥3 days, and the temperature is ≤35℃.

[0017] The resource treatment method of rice husk ash as described above, preferably, in step S2, the filter residue is washed by water for 2 times.

[0018] The resource treatment method of rice husk ash as described above, preferably, in step S3, the acid solution is added to make the pH of the system ≤3, and the time of acidification treatment is ≥3 days.

[0019] The resource treatment method of rice husk ash as described above, preferably, in step S4, 1 / 4-1 / 3 of the filter residue is taken as the filler of filter bed.

[0020] The resource treatment method of rice husk ash as described above, preferably, in step S5, after washing the preliminary silicon-rich activated carbon, drying at 65-75℃ to obtain silicon-rich activated carbon.

[0021] The resource treatment method of rice husk ash as described above, preferably, the strong alkali solution in step S1 is sodium hydroxide solution, potassium hydroxide solution or industrial waste alkali solution;

[0022] The acid solution in step S3 is nitric acid, sulfuric acid or industrial waste acid.

[0023] The resource treatment method of rice husk ash as described above, preferably, the silicon-rich activated carbon prepared in step S5 is used to return to the rice field to control chromium pollution and arsenic pollution in the rice field.

[0024] In the resource utilization method of rice husk ash described above, preferably, the liquid silicon fertilizer prepared in step S6 is used to spray the leaves of the rice field.

[0025] (III) Beneficial Effects

[0026] This invention involves alkaline extraction by mixing rice husk ash with a strong alkaline solution, followed by sequential washing and acidification of the resulting filter residue. A portion of the filter residue is used as filter bed packing to filter the acidified reaction solution, ensuring that most of the silica is adsorbed in the filter residue, with a small portion remaining in the filtrate. The final products are silicon-rich activated carbon and liquid silicon fertilizer. This invention utilizes filter bed filtration technology for silica extraction and cleverly uses the filter residue as the filter medium, significantly reducing material costs and process complexity, demonstrating good economic efficiency and operability. Furthermore, the method of this invention does not require high temperature and high pressure conditions, avoiding the high energy consumption problem of traditional rice husk ash silicon production processes. Simultaneously, no waste liquid or residue is generated during the entire operation, achieving clean production and exhibiting significant environmental advantages.

[0027] Furthermore, the silicon-rich activated carbon prepared by this invention can be directly returned to paddy fields to control the migration and pollution of heavy metals such as chromium and arsenic, thereby improving soil quality. The liquid silicon fertilizer can be used for foliar spraying in paddy fields to promote rice leaf growth, enhance crop resistance, and improve rice yield and quality. Therefore, this invention, through process optimization and resource recycling, effectively solves the problems of severe environmental pollution, high energy consumption, and complex processes commonly found in existing technologies, providing a new path for the efficient and green resource utilization of rice husk ash. Attached Figure Description

[0028] Figure 1 This is a flowchart of the resource utilization method for rice husk ash in this invention;

[0029] Figure 2 These are actual images of the filtrate obtained by filtration through the filter bed at different time periods in Example 1;

[0030] Figure 3 This is a photograph of the filtrate prepared in Example 1. Detailed Implementation

[0031] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, the present invention provides a method for the resource utilization of rice husk ash, comprising the following steps:

[0033] S1: Mix rice husk ash with a strong alkaline solution and perform alkaline extraction to obtain the first filtrate and filter residue.

[0034] S2: The filter residue is washed with water to obtain the second filtrate.

[0035] S3: Mix the first filtrate and the second filtrate, then add acid solution for acidification to obtain the reaction solution.

[0036] S4: Using part of the filter residue as filter bed packing, the reaction liquid is filtered through the packing to obtain preliminary silicon-rich activated carbon and filtrate.

[0037] S5: Wash and dry the preliminarily silicon-rich activated carbon to obtain silicon-rich activated carbon.

[0038] S6: Mix the filtrate with the remaining filter residue, remove the solids, and obtain liquid silicon fertilizer.

[0039] This invention utilizes filter bed filtration technology for silica extraction and employs filter residue as the filtration medium, significantly reducing material costs and process complexity, thus demonstrating excellent economic efficiency and operability. The processing method of this invention eliminates the need for high-temperature and high-pressure conditions, avoiding the high energy consumption problem of traditional rice husk ash silica extraction processes. Furthermore, it generates no waste liquid or residue throughout the entire operation, achieving clean production and exhibiting significant environmental advantages.

[0040] Furthermore, the silicon-rich activated carbon prepared by this invention can be directly returned to paddy fields to control the migration and pollution of heavy metals such as chromium and arsenic, thereby improving soil quality. The liquid silicon fertilizer can be used for foliar spraying in paddy fields to promote rice leaf growth, enhance crop resistance, and improve rice yield and quality. Therefore, this invention, through process optimization and resource recycling, effectively solves the problems of severe environmental pollution, high energy consumption, and complex processes commonly found in existing technologies, providing a new path for the efficient and green resource utilization of rice husk ash.

[0041] Preferably, in step S1 above, the molar ratio of silica in rice husk ash to hydroxide ions in the strong alkali is 2:1-4:3, the alkaline extraction treatment time is ≥3 days, the temperature is ≤35℃, and the strong alkali solution can be sodium hydroxide solution, potassium hydroxide solution, or industrial waste alkali solution. It should be noted that if industrial waste alkali solution is used, heavy metal ions need to be removed beforehand to avoid polluting farmland.

[0042] Taking sodium hydroxide as an example, the alkaline extraction principle of step S1 is as follows:

[0043] SiO₂ + 2NaOH = Na₂SiO₃ + H₂O

[0044] Because high temperature and high pressure conditions are not used, the reaction rate of silica in rice husk ash with alkali is relatively slow. Therefore, the alkaline extraction treatment time needs to be maintained at 3 days or more. If the reaction time is less than 3 days, the silica extraction rate in rice husk ash will be low.

[0045] The filter residue obtained in step S1 is activated carbon. Because activated carbon has a large specific surface area, some sodium silicate will be adsorbed onto its surface. Therefore, the filter residue needs to be washed in step S2 to avoid wasting silicon. Preferably, in step S2, the filter residue is washed twice with water, and the two washing solutions are mixed with the first filtrate from step S1.

[0046] Preferably, in step S3 above, acid is added to make the pH of the system ≤ 3, and the acidification treatment time is ≥ 3 days. The acid can be nitric acid, sulfuric acid, or industrial waste acid, preferably nitric acid, as nitric acid contains nitrogen, which is beneficial to plant growth in farmland. Similarly, since high temperature and high pressure conditions are not used, the reaction rate between sodium silicate and acid is relatively slow. Therefore, the acidification treatment time needs to be maintained at 3 days or more. If the reaction time is less than 3 days, the silicon extraction rate will be low. If industrial waste acid is used, heavy metal ions need to be removed in advance to avoid pollution of farmland.

[0047] Taking sulfuric acid as an example, the acidification treatment principle of step S3 is as follows:

[0048] Na2SiO3+H2SO4=SiO2+Na2SO4+H2O

[0049] Preferably, in step S4 above, 1 / 4 to 1 / 3 of the filter residue is used as the filter bed packing material to achieve the filtration of the reaction solution. Step S4 innovatively solves the technical problem of inefficient separation of nano-sized silica in acidification reaction solution by using part of the filter residue as filter bed packing material. Its core principle lies in the synergistic effect of the unreacted alkaline substances (such as sodium hydroxide) remaining in the filter residue and the porous activated carbon framework formed by the carbonization of rice husk ash: on the one hand, the multi-level pore structure of activated carbon can effectively adsorb nano-sized silica particles, achieving efficient enrichment of silicon components through physical interception and surface chemical bonding. On the other hand, the alkaline components remaining in the filter residue can dynamically neutralize the acidic environment of the reaction solution, increasing the pH of nano-silica, which not only avoids excessive agglomeration or dissolution of silica due to excessively low pH, but also solves the problem of needing to add additional alkaline regulators after traditional acidification. This process does not require the introduction of external filter media. Using activated carbon formed by the conversion of rice husk ash itself as the filter bed not only reduces the energy consumption and cost of nanomaterial separation, but also realizes the internal recycling of filter residue.

[0050] Furthermore, this step precisely controls the proportion of filter cake packing material used in the filter bed (1 / 4-1 / 3), ensuring both the porosity and adsorption performance of the silicon-loaded activated carbon while avoiding increased filtration resistance due to excessive packing material. In subsequent farmland applications, the resulting silicon-rich activated carbon exhibits a synergistic effect between the surface-loaded nano-silicon and the alkaline properties of the activated carbon. This allows it to chemically adsorb and fix chromium and arsenic ions in the soil while slowly releasing silicon to improve the soil microenvironment. This overcomes the application difficulties caused by pH imbalance or excessively small particle size in traditional silicon-based materials, truly achieving a closed-loop ecological benefit of "treating pollution with waste."

[0051] If the activated carbon is not filtered through the filter bed in step S4, the resulting silica-rich activated carbon will have a low pH, which will cause soil acidification when applied to farmland.

[0052] Preferably, in step S5 above, after washing the preliminary silicon-rich activated carbon, it is dried at 65-75°C to obtain silicon-rich activated carbon.

[0053] Analysis revealed that most of the silicon was adsorbed by activated carbon in step S4, forming silicon-rich activated carbon. The silicon dioxide in this activated carbon was at the nanoscale. However, a portion of the silicon, due to its larger particle size (reaching the micrometer scale), was not absorbed by the filter residue in the filter bed and remained in the filtrate. To fully utilize the silicon in the rice husk ash, this invention further mixes the filtrate with the remaining filter residue to obtain liquid silicon fertilizer.

[0054] Step S6 above, by mixing the filtrate with the remaining filter residue, achieves the transformation of silicate ions from a polymeric (jelly-like) state to an actively dispersed state, thereby preparing a liquid silicon fertilizer that can be directly applied. Its working principle is as follows: after acidification, silicate ions in the filtrate form highly polymerized gel-like silicate colloids due to pH fluctuations (usually 8-9.5), and this type of colloidal silicon is difficult for plants to absorb. The alkaline components remaining in the filter residue and the slightly alkaline surface of the activated carbon can undergo an acid-base neutralization reaction with the colloidal silicon, promoting the depolymerization of the silicate colloids and forming soluble monosilicic acid (H4SiO4) or oligomeric silicate ions, thereby breaking the colloidal network structure and allowing silicon to exist in a highly dispersed, active form in the liquid phase. This process achieves pH regulation through the recycling of the rice husk ash's own components, without the need for additional chemical regulators.

[0055] The mixed system undergoes solid-liquid separation to remove residual solid particles, ultimately yielding a liquid silicon fertilizer rich in active silicon, with the solid particles being neutral activated carbon. The silicon in this liquid silicon fertilizer exists in a small molecule form easily absorbed by plants. When applied to paddy fields, it is rapidly absorbed by rice leaves, promoting cell wall silicification, enhancing leaf uprightness to improve photosynthetic efficiency, and simultaneously improving plant resistance to pests and diseases and lodging resistance. Furthermore, trace amounts of potassium and calcium in the liquid silicon fertilizer further replenish soil nutrients. This step not only achieves full utilization of reaction byproducts but also avoids secondary pollution caused by wastewater discharge or the addition of neutralizing agents in traditional silicon fertilizer preparation through endogenous acid-base balance, combining environmental friendliness with agricultural applicability.

[0056] The working principles of the silicon-rich activated carbon and liquid silicon fertilizer prepared by this invention are as follows:

[0057] Arsenic in flooded soils mainly exists as arsenite (AsIII, >90%). Since AsIII and silicic acid are typical chemical analogs (having highly similar molecular diameters and dissociation constants pKa), rice absorbs AsIII through roots, translocates it to the xylem, and accumulates it in grains via silicic acid transport channels. Root application of rice husk-derived solid-phase highly active silicon (i.e., silicon-rich activated carbon) can significantly increase the available silicon content in the rice rhizosphere, reducing As accumulation by competitively inhibiting the absorption and translocation of AsIII by transporters at root and stem nodes. Simultaneously, foliar spraying of liquid silicon fertilizer can generate defensive signal transduction within the rice plant, inducing enhanced suberization and lignification of root cells, and further inhibiting the expression abundance of silicon transporters at root and stem nodes. Root application of rice husk-derived solid-phase highly active silicon before rice transplanting and spraying of liquid silicon at the end of tillering can produce a synergistic effect, strengthening the stable reduction and control of As accumulation in rice grains.

[0058] Furthermore, the silicon-rich activated carbon prepared by this invention has significant advantages over pure silica nanoparticles in agricultural applications. Its core effects and mechanisms of action are as follows:

[0059] Silica-rich activated carbon achieves its slow-release function of silica through a composite structure of porous carbon framework and silica. Pure silica nanoparticles, due to their large specific surface area and strong dispersibility, rapidly release silicon within minutes after being applied to the soil, leading to excessively high silicon concentrations in the short term and insufficient supply later. However, the microporous-mesoporous hierarchical structure of activated carbon physically binds the silica nanoparticles and forms a dynamic release system through the chemical bonding of surface hydroxyl groups with silicon, extending the silicon release period to over 15 days. This slow-release characteristic is highly compatible with the growth requirements of rice seedlings, avoiding the operational costs of frequent silicon supplementation. Simultaneously, it can stably maintain the effective silicon concentration in the soil by continuously generating silicate ions that competitively adsorb or co-precipitate with heavy metals, dynamically inhibiting their migration and bioavailability.

[0060] Heavy metal pollution is significantly affected by environmental factors such as rainfall and temperature. Traditional silicon fertilizers, due to their instantaneous release, are prone to fluctuations in silicon concentration. In contrast, the slow-release properties of silicon-rich activated carbon can dynamically respond to changes in soil moisture and ionic strength. For example, during the rainy season, when the soil solution is diluted, the release rate of silicon from the pores of activated carbon accelerates to compensate for silicon loss, while under drought conditions, the release slows down to avoid excessively high local concentrations. This adaptive regulation capability makes the fixation of chromium and arsenic more stable, making it particularly suitable for farmland environments with variable climates.

[0061] Furthermore, the slow-release effect of silicon-rich activated carbon in this invention originates from the synergistic mechanism between the multi-level pores of rice husk carbon and soil components. The specific principle is analyzed in layers as follows:

[0062] Rice husk carbon, after processing, forms a multi-level porous system. Micropores and mesopores exert a significant spatial confinement effect on the loaded nano-silica: micropores physically trap some silicon particles directly through their narrow pore size, while mesopores extend the diffusion path of silicon ions through their tortuous channels. Simultaneously, macropores act as transport channels, allowing soil moisture to slowly penetrate and selectively dissolve silicon components at the pore edges. This dynamic balance of "confinement-diffusion" allows the silicon release rate to be dually regulated by pore size distribution and wettability, achieving controlled release from hours to weeks.

[0063] Rice husk carbon contains impurities such as iron and aluminum oxides. Its surface hydroxyl groups can specifically complex with the silanol groups of silica in the soil environment, forming stable Si-O-Fe / Al covalent bonds. Furthermore, naturally occurring iron oxides in the soil further interact with silicon species on the activated carbon surface through interfacial complexation, constructing a silicon-carbon-iron ternary composite structure. This chemical bonding not only enhances the anchoring strength of silicon on the activated carbon carrier but also delays silicon release by altering its dissolution activation energy, causing it to exhibit pH-dependent dissociation kinetics in response to changes in soil solution ionic strength.

[0064] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.

[0065] Example 1

[0066] This embodiment provides a method for the resource utilization of rice husk ash, including the following steps:

[0067] S1: Rice husk ash was mixed with sodium hydroxide solution and subjected to alkaline extraction at room temperature for 3 days to obtain the first filtrate and filter residue. The molar ratio of silica to sodium hydroxide in the rice husk ash was 4:3.

[0068] S2: The filter residue is washed twice with water, and the washing liquids from the two washes are mixed to obtain the second filtrate. The washed solid is dried in an oven at 65°C to obtain the filter residue.

[0069] S3: Mix the first filtrate and the second filtrate, then add nitric acid to make the pH of the system 3, and acidify for 3 days to obtain the reaction solution.

[0070] S4: Using 1 / 3 of the filter residue as filter bed packing, the reaction liquid is filtered from top to bottom through the packing to obtain preliminary silicon-rich activated carbon and filtrate.

[0071] S5: Wash the preliminary silicon-rich activated carbon and then dry it at 65°C to obtain silicon-rich activated carbon.

[0072] S6: Mix the filtrate with the remaining filter residue, and filter to obtain liquid silicon fertilizer.

[0073] Figure 2 The filtrate after passing through the filter bed at different time periods in this embodiment is shown below. Figure 3 This is a photograph of the liquid silicon fertilizer prepared in this embodiment.

[0074] Example 2

[0075] This embodiment provides a method for the resource utilization of rice husk ash, including the following steps:

[0076] S1: Rice husk ash was mixed with potassium hydroxide solution and subjected to alkaline extraction at room temperature for 4 days to obtain the first filtrate and filter residue. The molar ratio of silicon dioxide to potassium hydroxide in the rice husk ash was 2:1.

[0077] S2: The filter residue is washed twice with water, and the washing liquids from the two washes are mixed to obtain the second filtrate. The washed solid is dried in an oven at 75°C to obtain the filter residue.

[0078] S3: Mix the first and second filtrates, then add sulfuric acid to make the pH of the system 2.8, and acidify for 5 days to obtain the reaction solution.

[0079] S4: Using 1 / 4 of the filter residue as filter bed packing, the reaction liquid is filtered from top to bottom through the packing to obtain preliminary silicon-rich activated carbon and filtrate.

[0080] S5: Wash the initial silicon-rich activated carbon and then dry it at 75°C to obtain silicon-rich activated carbon.

[0081] S6: Mix the filtrate with the remaining filter residue, and filter to obtain liquid silicon fertilizer.

[0082] Example 3

[0083] This embodiment provides a method for the resource utilization of rice husk ash, including the following steps:

[0084] S1: Rice husk ash is mixed with an industrial waste alkaline solution for removing heavy metal ions, and subjected to alkaline extraction at room temperature for 5 days to obtain the first filtrate and filter residue. The molar ratio of silica to hydroxide ions in the rice husk ash is 3:2.

[0085] S2: The filter residue is washed twice with water, and the washing liquids from the two washes are mixed to obtain the second filtrate. The washed solid is dried in an oven at 70°C to obtain the filter residue.

[0086] S3: Mix the first filtrate and the second filtrate, then add waste acid to remove heavy metal ions to make the pH of the system 2.6, and acidify for 4 days to obtain the reaction solution.

[0087] S4: Using 3.5 / 12 filter residue as filter bed packing, the reaction liquid is filtered from top to bottom through the packing to obtain preliminary silicon-rich activated carbon and filtrate.

[0088] S5: Wash the initial silicon-rich activated carbon and then dry it at 70°C to obtain silicon-rich activated carbon.

[0089] S6: Mix the filtrate with the remaining filter residue, and filter to obtain liquid silicon fertilizer.

[0090] The silicon-rich activated carbon prepared in Examples 1-3 was applied to paddy soils with the same soil conditions and paddy field growth conditions, respectively, keeping the effective silicon content in different soils the same. After the same time, the inorganic As content of rice in the soils of Examples 1-3 was found to have decreased by 44%, 42.3% and 41.9%, respectively.

[0091] The liquid silicon fertilizers prepared in Examples 1-3 were sprayed onto the leaves of plants in the same paddy field, maintaining the same spraying amount. Silicon and arsenic share the same transport factor. In paddy fields, arsenic accumulation is detrimental to rice growth, and arsenic accumulated in rice grains can further harm human health. Therefore, increasing the available silicon content in paddy fields can reduce the arsenic content. Testing showed that, compared to the control group without liquid silicon fertilizer, the available silicon content in the paddy plants of Examples 1-3 increased by approximately 300%, 240%, and 200%, respectively. Similarly, compared to the control group without liquid silicon fertilizer, the arsenic content in the paddy plants of Examples 1-3 decreased by 78%, 75%, and 77.6%, respectively.

[0092] In addition, compared with the blank group without liquid silicon fertilizer, the increase in the content of ferrous ions in the paddy plants of Examples 1-3 was detected to be between 300-400%, which did not exceed the range required by the plants. The increase in the content of ferrous ions in the mud can promote the photosynthesis of rice, increase the enzyme activity in the rice, improve the root health of rice, and promote nitrogen fixation.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for resourceful disposal of rice husk ash, characterized by, The method comprises the following steps: S1: mixing rice husk ash with a strong alkali solution to perform an alkali extraction treatment to obtain a first filtrate and a filter residue; S2: washing the filter residue with water to obtain a second filtrate; S3: mixing the first filtrate and the second filtrate, and then adding an acid solution to perform an acidification treatment to obtain a reaction liquid; S4: using part of the filter residue as a filter bed filler to filter the reaction liquid through the filler to obtain a preliminary silicon-rich activated carbon and a filtrate; S5: washing the preliminary silicon-rich activated carbon, and drying to obtain a silicon-rich activated carbon; S6: mixing the filtrate with the remaining filter residue, and removing the solid in the mixture to obtain a liquid silicon fertilizer.

2. The rice hull ash resource recovery method of claim 1, wherein, In step S1, the molar ratio of silicon dioxide in the rice husk ash to hydroxide in the strong alkali is 2:1-4:3, the time of the alkali extraction treatment is greater than or equal to 3 days, and the temperature is less than or equal to 35 DEG C.

3. The rice hull ash resource recovery method of claim 1, wherein, In step S2, the filter residue is washed with water twice.

4. The rice hull ash resource recovery method of claim 1, wherein, In step S3, the acid solution is added to make the pH of the system less than or equal to 3, and the time of the acidification treatment is greater than or equal to 3 days.

5. The rice hull ash resource recovery method of claim 1, wherein In step S4, 1 / 4-1 / 3 of the filter residue is used as the filter bed filler.

6. The rice hull ash resource recovery method of claim 1, wherein, In step S5, the preliminary silicon-rich activated carbon is washed, and then dried at 65-75 DEG C to obtain the silicon-rich activated carbon.

7. The rice hull ash resource recovery method of claim 1, wherein, The strong alkali solution in step S1 is a sodium hydroxide solution, a potassium hydroxide solution or an industrial waste alkali solution. The acid solution in step S3 is nitric acid, sulfuric acid or an industrial waste acid.

8. The rice hull ash resource recovery method of claim 1, wherein, The silicon-rich activated carbon prepared in step S5 is used to return to a rice field to control chromium pollution and arsenic pollution in the rice field.

9. The rice hull ash resource recovery method of claim 1, wherein, The liquid silicon fertilizer prepared in step S6 is used to spray the leaves of the rice field.

Images