Method for preparing calcium fulvate from forestry waste
By steaming, solid-liquid separation and catalyzed depolymerization of forestry waste bark, low-molecular weight calcium yellowate is prepared, which solves the problem of waste of bark resources and achieves efficient and low-cost industrial application.
Patent Information
- Application Number
- CN202510433736.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-08
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, tree bark is discarded in large quantities or is simply used, and it is not effectively used to prepare high value-added calcium chlorophenate, resulting in waste of resources and low utilization rate.
The mixture of forestry waste bark and calcium chloride and ammonia water is steamed and cooked, and then the solid-liquid separation, concentration and catalyzed depolymerization are used to reduce the molecular weight using catalysts such as aluminum chloride, zeolite and hydrogen peroxide to prepare small molecule calcium chlorate.
It has achieved large-scale preparation of low-molecular weight calcium yalcogenate by cheap methods, which has improved resource utilization and the physiological activity of the product, and is suitable for industrial applications.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of resource recycling industry, and particularly relates to a method for preparing calcium fulvate from forestry waste. Background Art
[0002] According to statistics, the current global bark production is approximately 400 million cubic meters, with a huge output. Except for a few barks such as Eucommia ulmoides and Quercus dentata barks which are used as raw materials for medicine or industrial products, the barks of most tree species are regarded as waste and are discarded, piled up, rotted in large quantities, or simply used as fuel for combustion. Compared with developed countries, the utilization degree of bark in China is very low, with an annual utilization amount of only tens of thousands of tons, and it is mostly used for extracting tannin extracts and fuel, with a single use. Research on the utilization of bark mainly includes the manufacture of particleboard and other building materials, extraction of active ingredients from bark, activated carbon, compost, soil conditioner, and adsorbent, etc.
[0003] Fulvic Acid (FA) is an organic compound with a relatively small molecular weight in humus. Compared with humic acid, fulvic acid has a higher aliphatic content, richer carboxyl, phenolic, and ketone groups, but weaker aromaticity. It can not only be used as a biostimulant in agricultural production but also promote biological growth and improve the availability of soil nutrients by regulating the carbon-nitrogen metabolic process. In addition to its growth-promoting effect, it can also induce changes in the primary and secondary metabolic pathways of plants related to abiotic stress tolerance, thereby reducing the damage caused by adversity stress to crops. In agricultural production, fulvic acid with a small molecular weight is not only more easily absorbed and utilized by plants, but also contains various growth-promoting functional groups with strong physiological activities, which have a wide range of effects on the growth, development, physiology, and biochemistry of plants. When the molecular weight is greater than 10 kDa, the physiological activity decreases, which is not conducive to its further application in agriculture. Natural fulvic acid mainly comes from non-renewable resources such as peat and weathered coal. With the depletion of natural resources and the continuous increase in the demand for fulvic acid resources, the development and utilization of renewable resources to produce and prepare fulvic acid are of great significance for maintaining the sustainable development among industry, agriculture, and the environment. Therefore, the development of a method system for converting and preparing high-value fulvic acid (salt) from bark can not only realize the high-value utilization of forestry residues but also provide a method reference for the preparation of low-molecular-weight fulvic acid (salt). Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a method for preparing calcium fulvate from forestry waste, which has wide raw material sources, a simple preparation method, and low costs, and can promote the large-scale preparation and industrial application of calcium fulvate.
[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing calcium fulvic acid from forestry waste. Using agricultural and forestry residues as raw materials, after mixing with a reaction solution, it is subjected to cooking treatment. After solid-liquid separation, an extrusion solution is obtained. The extrusion solution is concentrated to obtain a concentrated solution, and the concentrated solution is catalytically depolymerized to obtain calcium fulvic acid.
[0007] Further, the agricultural and forestry residues are selected from any one of the bark of processing residues of eucalyptus, poplar, and masson pine.
[0008] Further, the reaction solution is an aqueous solution containing calcium chloride and ammonia water. Among them, the mass ratio of agricultural and forestry residues to calcium chloride is 1:10wt% - 20wt%, and the mass ratio of bark to ammonia water is 1:10wt% - 30wt%.
[0009] Further, the cooking temperature is 170°C and the cooking time is 5h.
[0010] Further, the process of catalytically depolymerizing the concentrated solution is as follows: Mix the concentrated solution with formic acid or acetic acid aqueous solution, and then add a catalyst to react. The concentration of the substrate is 50%.
[0011] Further, the temperature of the catalytic depolymerization reaction is 40 - 100°C and the reaction time is 1 - 4h.
[0012] Further, the catalyst is aluminum chloride, zeolite, and hydrogen peroxide.
[0013] Further, the addition amount of aluminum chloride is 2 - 6wt%, the addition amount of zeolite is 3 - 9wt%, and the addition amount of hydrogen peroxide is 3 - 9wt%.
[0014] Further, the method for preparing calcium fulvic acid from the forestry waste includes the following steps:
[0015] (1) Mix the bark of agricultural and forestry residues with the reaction solution prepared from calcium chloride and ammonia water, where the addition amount of calcium chloride in the reaction solution is 10wt% - 20wt% and the addition amount of ammonia water is 10wt% - 30wt%, and cook at 170°C for 5h;
[0016] (2) After the reaction ends, solid-liquid separation is carried out to obtain an extrusion solution, which is concentrated to obtain a concentrated solution;
[0017] (3) Mix the concentrated solution with formic acid or acetic acid aqueous solution, add 2 - 6wt% aluminum chloride, 3 - 9wt% zeolite, and 3 - 9wt% hydrogen peroxide, and react at 40 - 190°C for 1 - 4h to obtain calcium fulvic acid.
[0018] Further, the molecular weight of the substances in the prepared concentrated solution < 10000Da, and the molecular weight of the substances after catalytic depolymerization < 1000Da.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] (1) The present invention uses forestry residue bark as raw material to prepare calcium fulvic acid in one-pot method. The raw material source is wide, the preparation method is simple, and the cost is low, which can promote the large-scale preparation and industrial application of calcium fulvic acid.
[0021] (2) The molecular weight of the calcium fulvic acid prepared by the present invention is < 1000 Da, with a low molecular weight and high physiological activity, which is beneficial to the promotion and application of the product. Detailed implementation mode
[0022] The present invention will be further clarified below in conjunction with specific embodiments. The embodiments are implemented on the premise of the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.
[0023] The bark in the following examples is all provided by Guangxi Paper Mill.
[0024] Example 1
[0025] A method for preparing calcium fulvic acid from forestry waste, comprising the following steps:
[0026] (1) Mix eucalyptus bark and reaction solution in a mass ratio of 1:4, wherein the addition amount of calcium chloride in the reaction solution is 15 wt%, and the addition amount of ammonia water is 20 wt%. Place it in an oil bath reaction tank for cooking and react at 170 °C for 5 h;
[0027] (2) After the reaction is completed, solid-liquid separation is carried out to obtain an extrusion liquid, and the extrusion liquid is concentrated to obtain a concentrated liquid;
[0028] (3) Mix the concentrated liquid with 1% (w / w) formic acid aqueous solution in a ratio of 1:1 (v / v), add 2 wt% aluminum chloride, 3 wt% zeolite and 3 wt% hydrogen peroxide, and react at 60 °C for 2 h to obtain liquid small molecule calcium fulvic acid.
[0029] Example 2
[0030] When preparing liquid calcium fulvic acid, replace eucalyptus bark with poplar bark, and the remaining preparation methods and parameters are the same as those in Example 1.
[0031] Example 3
[0032] When preparing liquid calcium fulvic acid, replace eucalyptus bark with masson pine bark, and the remaining preparation methods and parameters are the same as those in Example 1.
[0033] Example 4
[0034] When preparing liquid calcium fulvic acid, replace the formic acid aqueous solution with acetic acid aqueous solution, and the remaining preparation methods and parameters are the same as those in Example 1.
[0035] Example 5
[0036] When preparing liquid calcium fulvate, the formic acid aqueous solution is replaced with an acetic acid aqueous solution, and the remaining preparation methods and parameters are the same as those in Example 2.
[0037] Example 6
[0038] When preparing liquid calcium fulvate, the formic acid aqueous solution is replaced with an acetic acid aqueous solution, and the remaining preparation methods and parameters are the same as those in Example 3.
[0039] The results of the mass concentration and molecular weight of the extruded liquid and concentrated calcium fulvate prepared in Examples 1 to 6 are shown in Table 1 below.
[0040] Table 1 Mass concentration and molecular weight of the extruded liquid and concentrated calcium fulvate prepared in Examples 1 to 6
[0041]
[0042] As can be seen from Table 1, the concentrations of the extruded liquids of the three kinds of tree barks are all about 10%. Among them, the poplar bark and eucalyptus bark are slightly higher than the masson pine bark, indicating that the structure of the masson pine is relatively dense and not easily depolymerized. In terms of molecular weight, the average molecular weights of the soluble substances in the extruded liquid after depolymerization with calcium chloride / ammonia hydrolysis are all relatively high. Among them, the eucalyptus bark is 6008 Da, the poplar bark is 5219 Da, and the masson pine bark is 15051 Da, indicating that although the components of the bark are depolymerized and dissolved, the chemical bonds in its components do not break significantly. After concentration treatment, the solid matter concentrations of the concentrated liquids of the three kinds of tree barks all reach more than 60%, thus providing a basis for subsequent catalytic depolymerization. After catalytic depolymerization with the aluminum chloride / zeolite / hydrogen peroxide system, the molecular weights of calcium fulvate are significantly reduced, which are 840, 916 and 1203 Da respectively, indicating that the catalyst used in this study can effectively cut the chemical connection bonds inside the macromolecules and efficiently prepare small molecule calcium fulvate.
[0043] In addition, it can also be seen from the table that replacing formic acid with acetic acid during the catalytic depolymerization of macromolecular calcium fulvate also has excellent effects, and the molecular weights of the depolymerized fulvic acids are 901, 1074 and 1833 Da respectively.
[0044] Example 7
[0045] When preparing liquid calcium fulvate, the mass fraction of calcium chloride in the reaction solution in step 1) is 15%, and the addition amount of ammonia water is 20 wt% is replaced with the mass fraction of calcium chloride in the reaction solution being 10 wt% - 20 wt%, and the addition amount of ammonia water is 10 wt% - 30 wt%. The remaining preparation methods and parameters are the same as those in Example 2. The results are shown in Table 2.
[0046] Table 2 Effects of different dosages of calcium chloride and ammonia water on the molecular weight of calcium fulvate.
[0047]
[0048]
[0049] As can be seen from Table 2, when the dosage of 20wt% ammonia water is used, when the dosage of calcium chloride is increased from 10wt% to 20wt%, it has no effect on the solid content concentration of the extrusion liquid, the molecular weight of the soluble substances in the extrusion liquid, and the results of catalytic depolymerization, indicating that calcium chloride has no effect on the preparation of calcium fulvate. When the dosage of calcium chloride is 15wt%, when the dosage of ammonia water is increased from 10wt% to 20wt%, the concentration of the soluble substances in the separated liquid increases significantly, from 86.3 g / L to 120.2 g / L, and its molecular weight also decreases from 7358 to 4893 Da with the increase of the dosage of ammonia water, indicating that the increase of ammonia water can promote the depolymerization of bark components.
[0050] Example 8
[0051] When preparing liquid calcium fulvate, the temperature and time in the catalytic depolymerization process in step 3), that is, reacting at 60°C for 2 h, are changed to a temperature of 40 - 100°C and a time of 1 - 4 h, and the rest of the preparation methods and parameters are the same as those in Example 2. The results are shown in Table 3.
[0052] Table 3 Effects of different temperatures and times in the catalytic process on the molecular weight of calcium fulvate.
[0053]
[0054] As can be seen from Table 3, when the temperature is 40°C, the catalytic depolymerization effect is poor, and the molecular weight of calcium fulvate is still as high as 2980 Da. When the temperature is increased to 60°C, the molecular weight of fulvic acid decreases significantly to 916 Da. After that, continuing to increase the catalytic temperature has no effect on the molecular weight of calcium fulvate. At 60°C, the effect of time on the depolymerization of calcium fulvate was investigated and it was found that when the time was extended from 1 h to 2 h, the catalytic depolymerization effect was more prominent, and the molecular weight of calcium fulvate after catalysis was 916 Da. After that, continuing to extend the reaction time did not significantly improve the depolymerization effect of calcium fulvate.
[0055] Example 9
[0056] When preparing liquid calcium fulvate, the catalyst dosage in step 3), that is, adding 2wt% aluminum chloride, 3wt% zeolite and 3wt% hydrogen peroxide, is changed to adding 2 - 6wt% aluminum chloride, 3 - 9wt% zeolite and 3 - 9wt% hydrogen peroxide, and the rest of the preparation methods and parameters are the same as those in Example 2. The results are shown in Table 4.
[0057] Table 4 Effects of different catalyst dosages in the catalytic process on the molecular weight of calcium fulvate.
[0058]
[0059] As can be seen from Table 4, when aluminum chloride is not added, the system also has a certain catalytic depolymerization effect. The molecular weight of calcium fulvate after catalysis is 1896 Da. With the addition of aluminum chloride, the molecular weight of calcium fulvate further decreases. At dosages of 2 wt%, 4 wt%, and 6 wt%, the molecular weights of calcium fulvate are 916, 899, and 823 Da, respectively. When zeolite is not added, the depolymerization effect of the system is poor and the molecular weight is still as high as 4862 Da, indicating that zeolite plays a key role in the catalytic depolymerization of calcium fulvate. When 3 wt% zeolite is added, the molecular weight of calcium fulvate significantly decreases to 916 Da and gradually decreases to 846 Da (6 wt%) and 658 Da (9 wt%) as the zeolite addition amount increases. Since zeolite is expensive, a 3 wt% addition amount is selected as the preferred dosage. In addition, hydrogen peroxide also plays an important role in catalytic depolymerization, and its addition can also effectively reduce the molecular weight of calcium fulvate from 3685 to 916 Da. However, excessive hydrogen peroxide has no promoting effect on the catalytic system.
[0060] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for preparing calcium fulvic acid from forestry waste, characterized in that, Using agricultural and forestry residues as raw materials, after mixing with a reaction solution, they are subjected to cooking treatment. After solid-liquid separation, an extrusion solution is obtained. The extrusion solution is concentrated to obtain a concentrated solution, and the concentrated solution is catalytically depolymerized to obtain calcium fulvate.
2. The method for preparing calcium fulvate from forestry waste according to claim 1, characterized in that: The agricultural and forestry residues are selected from any one of the bark of eucalyptus, poplar, and masson pine processing residues.
3. The method for preparing calcium fulvate from forestry waste according to claim 1, characterized in that: The reaction solution is an aqueous solution containing calcium chloride and ammonia water. Among them, the mass ratio of agricultural and forestry residues to calcium chloride is 1:10wt% - 20wt%, and the mass ratio of bark to ammonia water is 1:10wt% - 30wt%.
4. The method for preparing calcium fulvate from forestry waste according to claim 1, characterized in that: The cooking temperature is 170°C, and the cooking time is 5h.
5. The method for preparing calcium fulvate from forestry waste according to claim 1, characterized in that: The process of catalytically depolymerizing the concentrated solution is as follows: The concentrated solution is mixed with formic acid or acetic acid aqueous solution, and then a catalyst is added for reaction. The concentration of the substrate is 50%.
6. The method for preparing calcium fulvate from forestry waste according to claim 1, wherein: The temperature of the catalytic depolymerization reaction is 40 - 100°C, and the reaction time is 1 - 4h.
7. The method for preparing calcium fulvate from forestry waste according to claim 5, characterized in that: The catalyst is aluminum chloride, zeolite, and hydrogen peroxide.
8. The method for preparing calcium fulvate from forestry waste according to claim 7, characterized in that: The addition amount of aluminum chloride is 2 - 6wt%, the addition amount of zeolite is 3 - 9wt%, and the addition amount of hydrogen peroxide is 3 - 9wt%.
9. The method for preparing calcium fulvate from forestry waste according to any one of claims 1 to 8, characterized in that: It includes the following steps: (1) Mix the bark of agricultural and forestry residues with the reaction solution prepared from calcium chloride and ammonia water, where the addition amount of calcium chloride in the reaction solution is 10wt% - 20wt%, and the addition amount of ammonia water is 10wt% - 30wt%. Cook at 170°C for 5h; (2) After the reaction ends, solid-liquid separation is carried out to obtain an extrusion solution, which is concentrated to obtain a concentrated solution; (3) Mix the concentrated solution with formic acid or acetic acid aqueous solution, add 2 - 6wt% aluminum chloride, 3 - 9wt% zeolite, and 3 - 9wt% hydrogen peroxide, and react at 40 - 190°C for 1 - 4h to obtain calcium fulvate.
10. The method for preparing calcium fulvate from forestry waste according to claim 9, characterized in that: The molecular weight of the substances in the prepared concentrated solution < 10000Da, and the molecular weight of the substances after catalytic depolymerization < 1000Da.