阅读说明：本技术 一种从矿物源中提取腐植酸的方法 (Method for extracting humic acid from mineral source ) 是由 赵瑛博 田宏哲 杜苛辉 钊华杰 王蒴 胡睿 于 2021-01-18 设计创作，主要内容包括：本发明公开一种从矿物源中提取腐植酸的方法。首先将矿物源粉碎过筛,采用低共熔溶剂提取,所述低共熔溶剂由氢键受体和氢键供体组成,所述氢键受体为氯化胆碱或甜菜碱,所述氢键供体为尿素。收集滤液,得到含腐植酸的提取液。提取液经酸析沉淀,过滤收集沉淀物,真空浓缩干燥,得到腐植酸；同时,将收集沉淀后的滤液经透析后,得到含有尿素、黄腐酸及植物生长调节剂的混合液,可作为液态肥使用,实现了矿物的综合利用。本发明制备方法简单、快速,提取溶剂对环境友好,提取的腐植酸和副产品可作为腐植酸肥料使用,解决了传统工艺中的资源浪费和环境污染问题,该制备方法具有很好的发展潜力。(The invention discloses a method for extracting humic acid from a mineral source. Firstly, crushing and sieving a mineral source, and extracting by adopting a eutectic solvent, wherein the eutectic solvent consists of a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride or betaine, and the hydrogen bond donor is urea. Collecting the filtrate to obtain the extracting solution containing humic acid. Precipitating the extract by acid precipitation, filtering, collecting precipitate, and vacuum concentrating and drying to obtain humic acid; meanwhile, the filtrate after the collection and the precipitation is dialyzed to obtain mixed liquid containing urea, fulvic acid and plant growth regulator, which can be used as liquid fertilizer, thus realizing the comprehensive utilization of minerals. The preparation method is simple and rapid, the extraction solvent is environment-friendly, the extracted humic acid and byproducts can be used as humic acid fertilizer, the problems of resource waste and environmental pollution in the traditional process are solved, and the preparation method has good development potential.)

1. A method for extracting humic acid from mineral sources is characterized by comprising the following steps:

mixing the eutectic solvent and a mineral source, oscillating, extracting at 85-100 ℃ for 4-5h, filtering the extracting solution, washing residues, and combining the filtrate and the washing solution to obtain a humic acid extracting solution;

adjusting the pH of the humic acid extracting solution to 2.0, standing, filtering, washing residues to be neutral, collecting precipitates, and performing vacuum concentration and drying to obtain the humic acid.

2. The method for extracting humic acid from mineral source as claimed in claim 1, wherein said eutectic solvent is composed of hydrogen bond acceptor and hydrogen bond donor, said hydrogen bond acceptor is choline chloride or betaine, said hydrogen bond donor is urea.

3. The method for extracting humic acid from mineral source according to claim 2, wherein the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1: (1-2).

4. The method for extracting humic acid from mineral source as claimed in claim 1, wherein the mineral source is one of weathered coal, peat or lignite.

5. The method for extracting humic acid from mineral source as claimed in claim 4, wherein the mineral source is dried, crushed and sieved with 80 mesh sieve before use.

6. The method for extracting humic acid from mineral source according to claim 1, wherein the mass ratio of the eutectic solvent to the mineral source is (15-20): 1.

7. the method for extracting humic acid from mineral source according to claim 1, wherein the pH of the humic acid extracting solution is adjusted by hydrochloric acid solution with concentration of 6 mol/L.

Technical Field

The invention relates to the field of preparation of humic acid, in particular to a method for extracting humic acid from a mineral source.

Background

Humic Acid (HA) is a macromolecular organic substance with biological activity, can be extracted from low-grade coal (weathered coal, peat and lignite), and HAs been widely applied in the fields of agriculture, environmental protection, chemical industry and the like. Especially humic acid fertilizer, has been widely noticed in agricultural production as green and environment-friendly fertilizer. In the prior art, various humic acid preparation methods exist, but most of the humic acid preparation methods adopt an alkali liquor extraction method, the process is relatively complicated, and a large amount of waste liquid is generated at the same time, so that the problem of serious environmental pollution is caused.

Chinese patent CN110804893A discloses a method for separating holocellulose in wood fiber by using choline eutectic solvent, wherein hydrogen bond donor is one of hydrochloric acid, sulfuric acid, formic acid, acetic acid or amino acid, and hydrogen bond acceptor is prepared by mixing choline chloride and sodium hydroxide or potassium hydroxide in organic solvent of methanol or ethanol, and then the hydrogen bond donor and acceptor are reacted at high temperature for 1-8h to prepare eutectic solvent. Therefore, the eutectic solvent prepared in the patent contains not only an organic solvent, but also strong base such as sodium hydroxide or potassium hydroxide, and is not a real "green" solvent. Chinese patent CN107814732A discloses choline eutectic solvent, a preparation method and application in extracting nekaline from flos Trollii, wherein a hydrogen bond receptor is choline chloride, a hydrogen bond donor is oxalic acid or succinic acid, the prepared eutectic solvent belongs to a strong acid solvent (pH <1), and in the patent, an aqueous solution (2-4:1) formed by the eutectic solvent and water is adopted to extract alkaloid active ingredients in the flos Trollii, but the eutectic solvent is not directly adopted to extract the active ingredients. Chinese patent CN108623709A discloses a method for extracting chitin, which uses a eutectic solvent prepared by mixing choline chloride and malic acid to extract chitin in shrimp shells or crab shells, wherein the eutectic solvent is also a strong acid solvent. In conclusion, the technical schemes all have the problem of environmental pollution.

The Eutectic solvent (Deep Eutectic Solvents) is a Eutectic mixture which is formed by mixing two or three solids such as hydrogen bond acceptors (such as choline chloride and betaine) and hydrogen bond donors (such as urea) in a certain stoichiometric ratio under high-temperature stirring and is liquid at room temperature or close to room temperature. The ionic liquid has the advantages of easily available raw materials, simple preparation process, low cost and the like, and has the characteristics of similar physical and chemical properties of ionic liquid, difficult volatilization, good solubility, low toxicity, biodegradability and the like.

Therefore, the method for preparing humic acid based on the eutectic solvent is developed, the extraction solvent is environment-friendly and biocompatible, the by-product can be comprehensively utilized as a liquid fertilizer, and the application potential is good.

Disclosure of Invention

The invention aims to provide a method for extracting humic acid from mineral sources, which overcomes the defects of an alkali liquor extraction method in the prior art and obviously reduces the production cost and the pollution to the environment.

In order to achieve the technical purpose, the invention provides the following technical scheme:

a method for extracting humic acid from mineral sources comprises the following steps:

mixing the eutectic solvent and a mineral source, oscillating, extracting at 85-100 ℃ for 4-5h, filtering the extracting solution, washing residues, and combining the filtrate and the washing solution to obtain a humic acid extracting solution;

adjusting the pH of the humic acid extracting solution to 2.0, standing, filtering, washing residues to be neutral, collecting precipitates, and performing vacuum concentration and drying to obtain the humic acid.

Further, the eutectic solvent consists of a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is choline chloride or betaine, and the hydrogen bond donor is urea.

Further, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1: (1-2).

Further, the eutectic solvent is betaine-urea or choline chloride-urea.

Further, the betaine-urea is prepared by mixing betaine and urea in a molar ratio of 1: 1.

Further, the betaine-urea is prepared by mixing betaine and urea in a molar ratio of 1: 2.

Further, the choline chloride-urea is prepared by mixing choline chloride and urea in a molar ratio of 1: 1.

Further, the choline chloride-urea is prepared by mixing choline chloride and urea in a molar ratio of 1: 2.

Further, the mineral source is one of weathered coal, peat or lignite.

Further, the mineral source is dried, crushed and sieved by a 80-mesh sieve before use.

Further, the mass ratio of the eutectic solvent to the mineral source is (15-20): 1.

further, the pH of the humic acid extracting solution is adjusted by a hydrochloric acid solution with the concentration of 6 mol/L. If the concentration of hydrochloric acid is too low, a large amount of hydrochloric acid solution is needed to adjust the pH value, and the amount of waste liquid is increased; the concentration is too high, the addition amount is not easy to control, the pH value is easy to adjust too low, and the yield is reduced.

Further, the filtrate is dialyzed through a semipermeable membrane in deionized water until no Cl is detected by silver nitrate in the solution^-And obtaining mixed liquid which can be used as liquid fertilizer.

Compared with the prior art, the invention has the beneficial effects that:

the invention extracts humic acid extracting solution from mineral source, through acid precipitation and precipitation, filtering and collecting precipitate, the mineral source humic acid obtained after vacuum concentration and drying is a product of organic matter decomposition, which is a mixture of natural organic macromolecules, the basic structure is aromatic ring and alicyclic ring, and the ring is connected with carboxyl, hydroxyl, carbonyl, quinonyl, methoxyl and other functional groups. The invention selects the mixture of choline chloride or betaine and urea to prepare eutectic solvent with pH value more than 10, belongs to weak base solvent, can extract humic acid in minerals, and has alkalinity weaker than that of alkaline solution such as sodium hydroxide or sodium pyrophosphate, so a great amount of impurities and metal ions can not be extracted.

The method for extracting the humic acid from the mineral source by using the eutectic solvent is green and environment-friendly in process, and the byproduct obtained after extracting the humic acid contains fulvic acid, urea, choline chloride or betaine and other mixtures, wherein the fulvic acid and the urea are agricultural fertilizers, and the choline chloride or the betaine belong to plant growth regulators, so that the stress resistance of plants can be improved. Therefore, the liquid fertilizer can be used as a liquid fertilizer, can well overcome the defects of an alkali liquor extraction method, and obviously reduce the production cost and the pollution to the environment.

Compared with the traditional alkali liquor extraction method or other high-purity humic acid preparation methods, the method has the advantages that the used extraction solvent is the eutectic solvent, the preparation is simple, the cost is low, and the method is environment-friendly. The preparation process is simple and quick, the environmental and biological compatibility is good, the production cost is low, and the extracted by-product can also be used as a liquid fertilizer, so that the comprehensive utilization of raw material coal can be realized.

Drawings

FIG. 1 is an infrared spectrum of humic acid obtained in example 1.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

Uniformly mixing an air-dried and crushed lignite sample (with humic acid content of 48%) which is sieved by a 80-mesh sieve with betaine-urea according to a mass ratio of 1:15, and then stirring and extracting at a temperature of 95 ℃ for 5 hours, wherein the molar ratio of the betaine to the urea is 1: 1. And after extraction is finished, filtering the extracting solution while the extracting solution is hot, washing residues for 3 times by using deionized water, and collecting filtrate and washing liquid to obtain humic acid extracting solution A. Adding 6mol/L hydrochloric acid solution into the extracting solution A, adjusting the pH to 2.0, and standing for 2 h; and then filtering to obtain filtrate B and residue, washing the residue to be neutral by using deionized water, collecting the precipitate, and performing vacuum concentration and drying to obtain a powdery humic acid product. The detection content is more than 97%. Transferring the filtrate B into a semi-permeable membrane bag, dialyzing with deionized water until the solution is dropwise added with 0.1mol/L silver nitrate solution and no turbidity is observed. And concentrating the dialyzed solution to obtain the mixed fertilizer.

Fig. 1 is an infrared spectrum of humic acid prepared in example 1, and as can be seen from fig. 1, the main absorption peaks in the infrared spectrum are absorption peaks generated by aromatic hydrocarbon, aliphatic hydrocarbon and oxygen-containing functional groups.

Example 2

Uniformly mixing an air-dried and crushed weathered coal sample (humic acid content is 44%) which is sieved by a 80-mesh sieve with betaine-urea according to a mass ratio of 1:20, and stirring and extracting for 4 hours at a temperature of 100 ℃, wherein the molar ratio of the betaine to the urea is 1: 2. And after extraction is finished, filtering the extracting solution while the extracting solution is hot, washing residues for 3 times by using deionized water, and collecting filtrate and washing liquid to obtain humic acid extracting solution A. Adding 6mol/L hydrochloric acid solution into the extracting solution A, adjusting the pH to 2.0, and standing for 2 h; and then filtering to obtain filtrate B and residue, washing the residue to be neutral by using deionized water, collecting the precipitate, and performing vacuum concentration and drying to obtain a powdery humic acid product. The detection content is more than 97%. Transferring the filtrate B into a semi-permeable membrane bag, dialyzing with deionized water until the solution is dropwise added with 0.1mol/L silver nitrate solution and no turbidity is observed. And concentrating the dialyzed solution to obtain the mixed fertilizer.

Example 3

Uniformly mixing an air-dried and crushed peat sample (humic acid content of 37%) which is sieved by a 80-mesh sieve with choline chloride-urea according to a mass ratio of 1:18, and then stirring and extracting at 85 ℃ for 4h, wherein the molar ratio of the choline chloride to the urea is 1: 1. And after extraction is finished, filtering the extracting solution while the extracting solution is hot, washing residues for 3 times by using deionized water, and collecting filtrate and washing liquid to obtain humic acid extracting solution A. Adding 6mol/L hydrochloric acid solution into the extracting solution A, adjusting the pH to 2.0, and standing for 2 h; and then filtering to obtain filtrate B and residue, washing the residue to be neutral by using deionized water, collecting the precipitate, and performing vacuum concentration and drying to obtain a powdery humic acid product. The detection content is more than 97%. Transferring the filtrate B into a semi-permeable membrane bag, dialyzing with deionized water until the solution is dropwise added with 0.1mol/L silver nitrate solution and no turbidity is observed. And concentrating the dialyzed solution to obtain the mixed fertilizer.

Example 4

Uniformly mixing an air-dried and crushed weathered coal sample (humic acid content 42%) which is sieved by a 80-mesh sieve with choline chloride-urea according to a mass ratio of 1:16, and stirring and extracting for 5h at 100 ℃, wherein the molar ratio of the choline chloride to the urea is 1: 2. And after extraction is finished, filtering the extracting solution while the extracting solution is hot, washing residues for 3 times by using deionized water, and collecting filtrate and washing liquid to obtain humic acid extracting solution A. Adding 6mol/L hydrochloric acid solution into the extracting solution A, adjusting the pH to 2.0, and standing for 2 h; and then filtering to obtain filtrate B and residue, washing the residue to be neutral by using deionized water, collecting the precipitate, and performing vacuum concentration and drying to obtain a powdery humic acid product. The detection content is more than 97%. Transferring the filtrate B into a semi-permeable membrane bag, dialyzing with deionized water until the solution is dropwise added with 0.1mol/L silver nitrate solution and no turbidity is observed. And concentrating the dialyzed solution to obtain the mixed fertilizer.

Example 5

Uniformly mixing an air-dried and crushed lignite sample (the content of humic acid is 52%) which is sieved by a 80-mesh sieve with choline chloride-urea according to the mass ratio of 1:17, and then stirring and extracting at the temperature of 90 ℃ for 5 hours, wherein the molar ratio of the choline chloride to the urea is 1: 1. And after extraction is finished, filtering the extracting solution while the extracting solution is hot, washing residues for 3 times by using deionized water, and collecting filtrate and washing liquid to obtain humic acid extracting solution A. Adding 6mol/L hydrochloric acid solution into the extracting solution A, adjusting the pH to 2.0, and standing for 2 h; and then filtering to obtain filtrate B and residue, washing the residue to be neutral by using deionized water, collecting the precipitate, and performing vacuum concentration and drying to obtain a powdery humic acid product. The detection content is more than 97%. Transferring the filtrate B into a semi-permeable membrane bag, dialyzing with deionized water until the solution is dropwise added with 0.1mol/L silver nitrate solution and no turbidity is observed. And concentrating the dialyzed solution to obtain the mixed fertilizer.

Example 6

Uniformly mixing an air-dried crushed peat sample (the content of humic acid is 35%) which is sieved by a 80-mesh sieve with betaine-urea according to the mass ratio of 1:19, and then stirring and extracting at the temperature of 85 ℃ for 4 hours, wherein the molar ratio of the betaine to the urea is 1: 1. And after extraction is finished, filtering the extracting solution while the extracting solution is hot, washing residues for 3 times by using deionized water, and collecting filtrate and washing liquid to obtain humic acid extracting solution A. Adding 6mol/L hydrochloric acid solution into the extracting solution A, adjusting the pH to 2.0, and standing for 2 h; and then filtering to obtain filtrate B and residue, washing the residue to be neutral by using deionized water, collecting the precipitate, and performing vacuum concentration and drying to obtain a powdery humic acid product. The detection content is more than 97%. Transferring the filtrate B into a semi-permeable membrane bag, dialyzing with deionized water until the solution is not turbid when 0.1mol/L silver nitrate solution is dripped into the solution. And concentrating the dialyzed solution to obtain the mixed fertilizer.

Comparative example 1

The difference from example 1 is that betaine-urea was replaced with a 1% NaOH solution.

The results show that the humic acid product prepared by extracting the sodium hydroxide solution has high content of impurities and metal ions, the humic acid content is less than 90 percent, the extraction process has high pollution, and the generated waste liquid contains fulvic acid components but cannot be comprehensively utilized.

Comparative example 2

The difference from example 1 is that betaine-urea was replaced with sodium pyrophosphate alkali solution having a mass concentration of 1.5%.

The results show that the content of impurities and metal ions in the humic acid product prepared by extracting sodium pyrophosphate alkali liquor is higher than that of the impurities and metal ions extracted by sodium hydroxide or eutectic solvent, the content of humic acid is less than 90%, and the extraction process not only pollutes the environment, but also causes resource waste, and cannot comprehensively utilize the fulvic acid component in the waste liquor.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included therein.