Method for extracting organic matters in glutamic acid fermentation tail liquid and measuring content of organic matters and extracting agent

Abstract

The invention belongs to the technical field of separation and extraction of organic matters in high-salt-content wastewater, and discloses a method for extracting organic matters in glutamic acid fermentation tail liquid and determining the content of the organic matters in the glutamic acid fermentation tail liquid and an extracting agent.The high-concentration glutamic acid fermentation tail liquid is filtered firstly and then mixed with the extracting agent.The high-concentration glutamic acid fermentation tail liquid is mixed with the extracting agent.The inorganic salt is separated out from the tail liquid, and wet filter residues and filtrate are obtained through a simple filtering method; the wet filter residue is wet inorganic salt, and the filtrate is organic matter extract liquor; respectively drying the wet filter residue and the filtrate to constant weight at a certain temperature to respectively obtain dried inorganic salt and organic matter, weighing the weight, and calculating the content of the inorganic salt and the organic matter in the tail liquid. The method can realize removal of inorganic salts in the glutamic acid fermentation tail liquid and extraction and content determination of the organic matters, for a glutamic acid granular fertilizer manufacturer, the organic matter content index can be used for predicting the caking condition of the granular fertilizer, and the extracted organic matters can be directly used for liquid chromatography-mass spectrometry tandem instrument sample loading, so that the method is suitable for large-scale industrial production. And carrying out all-component analysis on the organic matters.

Description

Technical Field

[0001] The present invention belongs to the technical field of separation and extraction of organic matter in high-salt wastewater, and particularly relates to a method for liquid-phase extraction and content determination of organic matter in glutamic acid fermentation tail liquor. Background Technique

[0002] The fermentation tail liquor of glutamic acid refers to the waste liquor (or concentrated liquor) discharged after the fermentation liquor in a monosodium glutamate factory extracts glutamic acid by isoelectric point. It is a kind of high-concentration organic wastewater, which has the characteristics of "five highs and one low", namely high COD, high BOD, high bacterial content, high sulfate content, high ammonia nitrogen content and low pH value, and is relatively difficult to treat. For a long time, monosodium glutamate factories have to spend a high cost to treat this wastewater to meet the national environmental protection requirements (such as the Comprehensive Wastewater Discharge Standard GB 8978-1996). However, the large amount of residual organic matter such as glutamic acid, bacteria, small molecular peptides, reducing sugars and organic acids contained in this tail liquor is a good raw material for producing amino acid-based functional fertilizers. At present, this type of granular fertilizer has been on the market for nearly 10 years, and has been widely recognized by the market, becoming a model for the resource utilization of industrial waste. However, due to the frequent changes in the production methods and processes of upstream monosodium glutamate factories, the organic matter content and composition of the produced glutamic acid fermentation tail liquor change every once in a while. This unpredictable change in raw material composition has caused serious interference and impact on the granulation production process of downstream glutamic acid granular fertilizer manufacturers. In order to respond to this change in organic matter composition in a timely manner and then make an effective adjustment to the granular fertilizer production process, it is necessary to regularly measure and monitor the organic matter content, composition, etc. in the glutamic acid fermentation tail liquor.

[0003] Since the composition of glutamic acid fermentation tail liquor is extremely complex, including a large amount of ammonium sulfate and tens of thousands of small molecular organic compounds, before using advanced technologies such as mass spectrometry to determine the specific composition and content of its organic matter, it is often necessary to first remove a large amount of difficult-to-volatilize inorganic salts such as ammonium sulfate. Commonly used methods for removing inorganic salts and extracting organic matter include centrifugal separation, flocculation precipitation, evaporation crystallization, liquid-phase (solvent) extraction, solid-phase extraction, membrane separation, salting-out crystallization, etc. The specific method to be selected needs to be based on the composition, polarity, solubility, extraction rate, determination time and cost control requirements of the mixture.

[0004] The patents with publication numbers CN 109987614 A and CN 114380443 A respectively obtained bacterial protein and ammonium sulfate by methods such as centrifugal separation, flocculation precipitation, and evaporation crystallization, which are convenient and simple. However, other organic matter in the tail liquor, such as glutamic acid, small molecular peptides, reducing sugars and organic acids, still remain in the mother liquor.

[0005] Patents with publication numbers CN213965262U and CN211111880U extract organic matter components from rocks and petroleum respectively. The innovation points of their technical solutions mainly lie in enhancing the extraction effect through improvements to extraction devices, condensation devices, etc.; CN114853292A mainly improves the extraction efficiency by increasing the temperature and pressure during the extraction process and strengthening the mass transfer conditions, such as using ultrasonic, microwave or vibration methods. All three of these patents use the liquid-liquid extraction method, but still use traditional extraction agents, making it difficult to substantially improve the extraction effect. Moreover, custom glass instruments or special equipment need to be purchased, which is expensive and inconvenient for promotion.

[0006] Literatures adopting the solid-phase extraction method include patents with publication numbers CN111795884A and CN218823507U. They use solid-phase extraction columns. During the process of extracting organic matter, 5 - 10 different elution or washing steps are arranged. The process is cumbersome, the extraction columns are expensive, the number of times they can be reused is small, the process takes a long time, and the amount of organic matter separated is small. In addition, the sample composition is affected to varying degrees, making it difficult to obtain the organic matter with its original content and composition. Therefore, the practical value of the solid-phase extraction method is not high.

[0007] The salting-out crystallization method has unique advantages in treating high-salt organic wastewater: it can separate organic matter and inorganic salts simultaneously. Patent CN108586275A adopts the salting-out crystallization method and uses ethanol as the extraction agent to extract the organic matter in the concentrated threonine fermentation broth. However, due to the limited solubility of ethanol in polar organic matter, there is a problem of incomplete separation of salt and organic matter during extraction. When using other extraction solvents, such as ethyl acetate, toluene, tetrahydrofuran, carbon tetrachloride, etc., no salt precipitation is observed and the effect is even worse.

[0008] The national industry standard (NY / T 1976 - 2010) does not extract organic matter, but uses titration method to determine and indirectly estimate the organic matter content. However, this method needs to use toxic potassium dichromate. Not only the waste liquid generated is toxic and requires special disposal, but also the titration process takes a long time, and many instruments are used during the operation process. A fixed conversion coefficient needs to be uniformly used during the calculation of the organic matter content, which makes this method unable to adapt to the determination of the organic matter content with component changes. The result (organic matter content) of this method is also only a rough estimated range. Therefore, this method has poor adaptability and is limited in application in factories.

[0009] Through the above analysis, the problems and defects existing in the prior art are summarized as follows: for the published methods, some do not extract organic matter completely and have poor extraction effects; some have high requirements for experimental devices and instruments, and have many experimental steps, long time consumption, and the processing process is likely to cause distortion of the original samples; some reagents are toxic, and the calculation process requires conversion based on empirical values, and the method is not sensitive to differences in raw material types or even batches. Based on this, a method for extracting and determining the content of organic matter in glutamic acid fermentation tail liquor is provided now, which can eliminate the drawbacks existing in the existing methods. Summary of the Invention

[0010] In view of the problems existing in the prior art, the present invention provides a method for extracting and determining the content of organic matter in glutamic acid fermentation tail liquor.

[0011] The present invention is implemented as follows: a method for extracting and determining the content of organic matter in glutamic acid fermentation tail liquor. First, filter the high-concentration glutamic acid fermentation tail liquor, and then mix it with an extractant. The inorganic salts (mainly ammonium sulfate) will precipitate from the tail liquor. By using a simple filtration method, wet filter residue and filtrate can be quickly obtained. The wet filter residue is wet inorganic salts, and the filtrate is the organic matter extract. Dry the wet filter residue and filtrate to a constant weight at a certain temperature respectively to obtain dry inorganic salts and organic matter, weigh them, and then the accurate contents of inorganic salts and organic matter in the tail liquor can be calculated.

[0012] Further, the method for extracting and determining the content of organic matter in glutamic acid fermentation tail liquor includes the following steps:

[0013] (1) Filtration and density determination of glutamic acid fermentation tail liquor: Measure 50 mL of glutamic acid fermentation tail liquor, use a Buchner funnel and a 100-mesh nylon mesh for filtration, collect the filtrate and transfer it to a precision measuring cylinder. Combine the weighed mass data to calculate the density of the filtrate, denoted as ρ, with the unit g·cm -3 ;

[0014] (2) Adding the extractant: Accurately measure 10 mL of glutamic acid fermentation tail liquor with a pipette and place it in a 25-mL colorimetric tube. Then accurately measure 1 - 10 mL of the extractant with a pipette and add it to the colorimetric tube. Tighten the stopper of the colorimetric tube and shake the colorimetric tube for 1 - 30 min.

[0015] (3) Filtration and washing: Filter the mixed solution using a filter medium and a filtration device; then measure 1 - 5 mL of the extractant with a pipette and place it in the colorimetric tube. Cover the tube stopper tightly, wash the inner wall and stopper of the colorimetric tube thoroughly, and filter the washing solution to obtain wet filter residue and filtrate. The wet filter residue is the inorganic salts removed from the glutamic acid fermentation tail liquor, and the organic matter is dissolved in the filtrate.

[0016] (4) Collect the filtrate and measure its volume: After confirming that no more liquid flows out from the lower end of the Buchner funnel, stop the suction filtration, and measure the volume of the filtrate with a measuring cylinder (accurate to 0.1 mL). This filtrate is the organic matter extract obtained by extracting from the glutamic acid fermentation tail liquor;

[0017] (5) Drying and weighing of the extract: Take a clean and dry glass petri dish, place it on a balance with an absolute accuracy of 0.1 mg (i.e., 0.0001 g) to weigh and record its weight, denoted as m0 (g); Use a pipette with a precision of 0.1 mL to suck the filtrate equivalent to 1 / 10 of the total volume of the filtrate (rounded to one decimal place) and transfer it into the glass petri dish. Record the total mass of the petri dish and this part of the filtrate as m1 (g). Put the glass petri dish into an electrothermal constant temperature forced air drying oven at 80 °C and dry for a period of time. After the glass petri dish reaches a constant weight, take out the glass petri dish, cool it to room temperature and then weigh its mass, denoted as m2 (g);

[0018] (6) Calculate the organic matter content; The calculation formula is as follows:

[0019]

[0020] Where: ρ, the density of the glutamic acid fermentation tail liquor, g·cm -3 ; W1, the mass fraction of organic matter in the organic matter extract; W2, the mass fraction of organic matter in the original glutamic acid fermentation tail liquor.

[0021] Furthermore, the extractant is one or a mixture of several of dimethyl sulfoxide, N,N-dimethylformamide, 1,4-dioxane, methanol, acetic acid, phenol.

[0022] Furthermore, the filtration medium is qualitative filter paper, 0.45 μm filter membrane, filter cloth, and the filtration device is a Buchner funnel, a vacuum glass filter.

[0023] Furthermore, place the qualitative filter paper in the Buchner funnel, connect the suction flask to the water circulation vacuum pump, pour the mixture into the Buchner funnel for suction filtration, or filter with a 0.45 μm filter membrane.

[0024] Furthermore, the drying temperature ranges from 30 - 180 °C, and the operation is carried out under normal pressure or reduced pressure; The drying time is 1 - 6 h.

[0025] The method and extractant provided by the present invention can also be used for the extraction and content determination of organic matter in the granular fertilizer produced mainly from the glutamic acid fermentation tail liquor.

[0026] Combined with the above technical solutions and the solved technical problems, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0027] First, in the present invention, after the extractant is mixed with the glutamic acid fermentation tail liquor at room temperature, suction filtration is carried out. With the help of common instruments such as precision measuring cylinders, glass petri dishes, constant temperature forced air drying ovens and analytical balances, the removal of inorganic salts, the extraction and content determination of organic matter in the tail liquor (see Example 1) and granular fertilizers (see Examples 3 and 4) can be achieved. The instruments used are simple, the experimental cost is low, and the operation is fast. If the tail liquor is dried first and then the organic matter is extracted, the extraction efficiency can be further improved (see Example 2).

[0028] Analyzed from the principle, dimethyl sulfoxide (DMSO) is a non-protonated polar organic solvent, known as the "universal solvent". Because the sulfur atom of DMSO can interact with the aromatic ring π bond, it has a strong dissolving ability for organic substances such as aromatic acids, aromatic bases and polycyclic aromatic hydrocarbons, so it is often used in the extraction of petroleum components and soil organic matter; in addition, the oxygen atom of DMSO can form hydrogen bonds with the hydroxyl groups of organic substances, enabling DMSO to have strong interactions with polar groups such as -COOH and -NH, resulting in DMSO having excellent dissolving ability for common polar biological molecules such as amino acids, various organic acids, sugars and proteins, and being applied in the three major fields of industry, medicine and molecular biology. For the above two reasons, DMSO has its unique advantages in the extraction of complex organic matter. Therefore, the present invention uses DMSO as the main extraction solvent, and this solvent can remove ammonium sulfate and extract organic matter from high-concentration glutamic acid fermentation tail liquor, and finally realize the determination of the mass fraction of organic matter in the tail liquor.

[0029] Second, compared with the solid-phase extraction method, the method of the present invention can directly obtain the physical object of organic matter, so the accurate mass fraction of organic matter can be calculated, and these organic matters can also be used for subsequent component analysis (such as mass spectrometry analysis, etc.). It can adapt to the glutamic acid fermentation tail liquor with batch component fluctuations (as shown in Examples 3 and 4 below, the caking degree of granular fertilizers produced from tail liquors with different organic matter contents is different), and even extend to other high-salt wastewaters; the present invention uses inexpensive and low-toxic organic solvents such as dimethyl sulfoxide as the extractant, and the extraction and separation are relatively complete, and no toxic reagents are used and no solid hazardous wastes are generated.

[0030] Third, when extracting organic matter by the method of the present invention, compared with the popular high-end solid-phase extraction method, the cost can be reduced from 200 yuan per time to 20 yuan per time, greatly reducing the detection cost and improving the production efficiency of enterprises; when determining the content of organic matter, the highly toxic substance potassium dichromate is not used, which meets the national policy environmental protection requirements, and enterprises using this method will be supported by national policies.

[0031] Currently, the methods for organic matter extraction include centrifugal separation, flocculation precipitation, evaporation crystallization, liquid phase (solvent) extraction, solid phase extraction, membrane separation, salting-out crystallization, etc.; in the liquid phase extraction method, the disclosed extractants are ethanol, ethyl acetate, toluene, tetrahydrofuran, carbon tetrachloride, etc.; the conventional method for determining the organic matter content is the potassium dichromate oxidation method of the national industry standard (NY / T 1976-2010), while the method of the present invention uses other extractants, including a mixed solution of one or several of dimethyl sulfoxide, N,N-dimethylformamide, 1,4-dioxane, methanol, acetic acid, and phenol, which has the advantages of simple steps, rapid determination, very low cost, easy promotion, etc., and will fill the technical gaps at home and abroad in the industry.

[0032] The treatment of organic sewage with high salt content is a difficult problem in the industry. The high analysis cost restricts the healthy and rapid development of the industry. However, using the method of the present invention to determine its components is simple and effective, which is obviously conducive to accelerating the improvement and upgrading of the sewage treatment technology of this kind and promoting the rapid development of the sewage treatment industry of this kind.

[0033] From the history and trend of the development of organic matter extraction technology, liquid phase extraction belongs to a relatively old technology. There are more literatures on solid phase extraction published now. By modifying the surface of the packing, stationary phases with different affinities can be obtained, thus continuously improving the effect of solid phase extraction; however, problems such as the incompleteness of solid phase extraction and the high cost of the packing have not yet seen breakthrough progress, which makes the liquid phase extraction method still competitive. When liquid phase extraction is applied in production, volatile extractants such as ethanol and ethyl acetate are often selected. However, for organic wastewater with high salt content, its efficient treatment is a worldwide problem. Ethanol has limited solubility in polar organic matter, and there is a problem of incomplete separation of salt and organic matter during extraction. Due to its special molecular structure, DMSO has excellent solubility in substances such as aromatic compounds, proteins, sugars, and various organic acids. There are often studies on its use in industrial production, chemical reactions, biochemical experiments, and medicine, but there are few reports on using DMSO in liquid phase extraction. This is because DMSO is a high-boiling solvent and is relatively difficult to completely remove. Using it in large quantities in production will cause various practical production problems, such as high recovery cost and pollution of residual solvents. However, when DMSO is used as an extractant for determining the organic matter content, the dosage per time is 10-20 mL, the cost is very low, and it can be removed by drying, and the pollution to the product and the environment is controllable. Therefore, the present invention has strong practicability, especially has market competitiveness in the field of fermentation tail liquid. Description of the Drawings

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the attached drawings required in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a flowchart of the method for extracting organic matter and measuring its content in the glutamic acid fermentation tail liquid provided by the embodiments of the present invention.

[0036] Figure 2 It is the appearance diagram of the crystals precipitated after extracting the tail liquid with ethanol (a) and DMSO (b). Detailed implementation manners

[0037] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further details the present invention in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] This method first filters the glutamic acid fermentation tail liquid, and uses a Buchner funnel and a 100-mesh nylon net to remove large particle suspensions, thereby obtaining a relatively homogeneous liquid sample. Subsequently, the density (ρ) of the tail liquid is calculated by the weighing method in cooperation with volume measurement. This process not only ensures the homogeneity of the solution components in the subsequent extraction process, but also provides the necessary density parameters for calculating the organic matter content by volume in the subsequent process.

[0039] After accurately measuring a certain volume of the glutamic acid fermentation tail liquid, an appropriate amount of extractant is added, and the extractant is fully contacted with the tail liquid by shaking under a closed state. A selective affinity is formed between the extractant and the organic matter in the tail liquid, and the organic matter is "extracted" from the complex matrix. By shaking and mixing fully, the extractant molecules can penetrate the liquid-liquid interface and transfer the target organic matter into their molecules, thereby realizing the effective separation of the organic matter.

[0040] The oscillated mixture is filtered through a special filter medium (such as qualitative filter paper, 0.45μm filter membrane or filter cloth), and liquid-solid separation is achieved by using a Buchner funnel or a vacuum glass filter. At this time, the filtrate mainly dissolves the extracted organic matter, while the wet filter residue is rich in inorganic salts removed from the tail liquid. In order to further ensure the complete recovery of the organic matter, the inner wall and the plug of the filter tube also need to be washed to ensure that the residues of the extractant and the organic matter are fully recovered, and the volume of the extract accurately reflects the organic matter content in the tail liquid.

[0041] Transfer the extracted filtrate to a clean and dry glass petri dish in a certain proportion. By controlling the drying temperature (30 - 180 °C, under normal or reduced pressure conditions) and time (1 - 6 h), completely dry the organic matter in the filtrate. After drying, weigh it accurately with a precision balance and record the total mass of the petri dish and the residue. Combining the initial filtrate volume and the density of the tail liquid, use formulas W1 and W2 to calculate the mass fraction of the organic matter in the extract and the original tail liquid respectively, thus completing the determination of the total organic matter content.

[0042] During the extraction process, the selected extractant can be any one of dimethyl sulfoxide (DMSO), N,N - dimethylformamide (DMF), 1,4 - dioxane, methanol, acetic acid, phenol, or a composite extractant formed by mixing multiple solvents according to experimental requirements. The choice of extractant is based on the polarity, solubility, and separation efficiency of the target substance to ensure optimized extraction effects in different solvent systems. The mixing ratio of the mixture can be optimized through experiments according to the solubility parameters of different systems.

[0043] During the filtration process, the filtration media used can include qualitative filter paper (suitable for ordinary rough filtration), 0.45 μm filter membrane (suitable for removing fine particles), and filter cloth (suitable for large - volume solid - liquid separation). Select the appropriate medium according to the actual experimental requirements. In terms of the filtration device, a Buchner funnel (suitable for rapid suction filtration) or a vacuum glass filter (suitable for fine filtration and efficient separation) can be used to ensure that impurities and precipitates in the liquid are fully removed.

[0044] If using a Buchner funnel for filtration, first lay the qualitative filter paper flat on the bottom of the Buchner funnel and ensure that the filter paper edge fits tightly with the funnel. Subsequently, connect the suction flask to the water - circulating vacuum pump and turn on the vacuum pump to form a negative - pressure suction filtration environment. The mixed solution of the experimental sample is slowly poured into the Buchner funnel and rapidly passes through the filter paper for solid - liquid separation under the action of negative pressure and enters the suction flask. If using a 0.45 μm filter membrane for filtration, the filter membrane needs to be fixed on the vacuum filtration device, and then the mixed solution is slowly poured in so that tiny particle impurities can be removed more efficiently.

[0045] During the filtration process, ensure the stability of the vacuum pump pressure to avoid damage to the filter paper or filter membrane due to excessive negative pressure, which affects the filtration efficiency. At the same time, observe the clarity of the filtrate during the suction filtration process. If the filtrate still contains fine suspended matter, consider increasing the number of filtration layers or replacing the filter membrane with a finer pore size. After the experiment, clean the filtration device in a timely manner and recover the organic solvent to reduce experimental pollution. When using extractants such as phenol with volatility or corrosiveness, operate in a fume hood to avoid safety hazards caused by volatilization.

[0046] Example 1

[0047] Measure approximately 50 mL of the glutamic acid fermentation tail liquid, filter it with qualitative filter paper (pretreatment), and measure the density value of the treated tail liquid to be 1.26 g·cm -3 .

[0048] Accurately measure 10 mL of the pretreated tail liquid into a 25-mL colorimetric tube. Use dimethyl sulfoxide (DMSO) as the extractant, accurately measure 10 mL and add it to the colorimetric tube, and shake for 3 min to ensure thorough mixing. Then, filter the mixed liquid with a Buchner funnel, and add 5 mL of dimethyl sulfoxide to wash the colorimetric tube and its stopper to obtain wet filter residue and filtrate. The filter residue is the removed inorganic salts, and the filtrate is the organic matter extract of the tail liquid.

[0049] Accurately measure the volume of the filtrate with a graduated cylinder to be 19.0 mL. Take 1 clean and dry glass petri dish, record its mass as m0. Use a pipette to transfer 1 / 10 of the filtrate volume, that is, 1.9 mL, into the glass petri dish, and record the mass of this part of the filtrate as m1. Place the glass petri dish in an electrothermal constant-temperature forced-air drying oven at 80 °C and dry for 6 h. After the glass petri dish has reached a constant weight, take out the petri dish, cool it to room temperature, and then weigh its mass as m2 (the relevant data is shown in Table 1).

[0050] Calculate the mass fraction of organic matter (W1) in the organic matter extract and the mass fraction of organic matter (W2) in the original glutamic acid fermentation tail liquid according to formulas (1) and (2). The calculation results are shown in Table 1.

[0051] Example 2

[0052] Measure approximately 10 mL of the glutamic acid fermentation tail liquid into a 9-cm petri dish, place it in an electrothermal constant-temperature forced-air drying oven, and dry at 120 °C for 4 h to obtain flaky solid sample 1. Crush the solid sample 1 in a pulverizer to a powder of approximately 100 mesh. Place the powder in a 25-mL colorimetric tube, accurately measure 10 mL of dimethyl sulfoxide (DMSO) with a pipette and add it to the colorimetric tube, and shake for 3 min to ensure thorough mixing. Then, filter the mixed liquid with a Buchner funnel, and add 5 mL of dimethyl sulfoxide to wash the colorimetric tube and its stopper to obtain wet filter residue and filtrate. The wet filter residue is the removed inorganic salts, and the filtrate is the organic matter extract in the tail liquid.

[0053] After ensuring that there is no more filtrate flowing out from the lower end of the Buchner funnel, stop suction filtration. Measure the volume of the filtrate with a graduated cylinder to be 12 mL. Take 1 clean and dry glass petri dish, record its mass as m0. Use a pipette to transfer 1 / 10 of the filtrate volume, that is, 1.2 mL, into the glass petri dish, and record the mass of this part of the filtrate as m1. Place the glass petri dish in an electrothermal constant-temperature forced-air drying oven at 80 °C and dry for 6 h. After the glass petri dish has reached a constant weight, take out the petri dish, cool it to room temperature, and then weigh its mass as m2 (the relevant data is shown in Table 1).

[0054] Calculate the mass fraction of organic matter (W1) in the organic matter extraction solution and the mass fraction of organic matter (W2) in the original glutamic acid fermentation tail liquor according to Formulas (1) and (2). The calculation results are shown in Table 1.

[0055] Example 3

[0056] Accurately weigh 5 g of the crushed caked granular fertilizer into a 25-mL colorimetric tube. Use a pipette to accurately measure 10 mL of dimethyl sulfoxide (DMSO) and add it to the colorimetric tube. Oscillate for 3 min to ensure thorough mixing. Then, filter the mixture with a Buchner funnel and add 5 mL of dimethyl sulfoxide to wash the colorimetric tube and its stopper to obtain wet filter residue and filtrate. The wet filter residue is the removed inorganic salts, and the filtrate is the organic matter extraction solution of the caked granular fertilizer.

[0057] After ensuring that no more filtrate flows out from the lower end of the Buchner funnel, stop the suction filtration. Measure the volume of the filtrate with a measuring cylinder, which is 12 mL. Take 1 clean and dry glass petri dish, record its mass as m0. Use a pipette to transfer 1 / 10 of the filtrate volume, that is, 1.2 mL, into the glass petri dish, and record the mass of this part of the filtrate as m1. Place the glass petri dish in an electrothermal constant-temperature forced-air drying oven at 80 °C for 6 h. After the glass petri dish has reached a constant weight, take out the petri dish, cool it to room temperature, and then weigh its mass as m2 (the relevant data are shown in Table 1).

[0058] Calculate the mass fraction of organic matter (W1) in the organic matter extraction solution of the caked granular fertilizer and the mass fraction of organic matter (W3) in the original caked granular fertilizer according to Formulas (1) and (3). The calculation results are shown in Table 1.

[0059]

[0060] Where: ρ, the density of the glutamic acid fermentation tail liquor, g·cm -3 ; W3, the mass fraction of organic matter in the granular fertilizer.

[0061] Example 4

[0062] Accurately weigh 5 g of the crushed non-caked granular fertilizer into a 25-mL colorimetric tube. Use a pipette to accurately measure 10 mL of dimethyl sulfoxide (DMSO) and add it to the colorimetric tube. Oscillate for 3 min to ensure thorough mixing. Then, filter the mixture with a Buchner funnel and add 5 mL of dimethyl sulfoxide to wash the colorimetric tube and its stopper to obtain wet filter residue and filtrate. The wet filter residue is the removed inorganic salts, and the filtrate is the organic matter extraction solution of the non-caked granular fertilizer.

[0063] After ensuring that no more filtrate flows out from the lower end of the Büchner funnel, stop the suction filtration. Measure the volume of the filtrate with a graduated cylinder, which is 12 mL. Take 1 clean and dry glass petri dish, record its mass as m0. Use a pipette to transfer 1 / 10 of the filtrate volume, that is, 1.2 mL, into the glass petri dish, and record the mass of this part of the filtrate as m1. Put this glass petri dish into an electrothermal constant temperature forced air drying oven at 80 °C and dry for 6 h. After the glass petri dish has reached a constant weight, take out the petri dish, cool it to room temperature, and then weigh its mass as m2 (the relevant data is shown in Table 1).

[0064] Calculate the mass fraction of organic matter (W1) in the organic matter extract of the non-caking granular fertilizer and the mass fraction of organic matter (W3) in the original non-caking granular fertilizer according to formulas (1) and (3). The calculation results are shown in Table 1.

[0065] Table 1 Determination results of the organic matter content of glutamic acid fermentation tail liquor and granular fertilizer in the examples and related calculation data

[0066]

[0067] As Figure 2 shown, after using ethanol and dimethyl sulfoxide (DMSO) to extract the organic matter from the glutamic acid fermentation tail liquor respectively, the appearance of the ammonium sulfate crystals obtained by filtration has obvious differences. As shown in (a) in the figure, the ammonium sulfate crystals obtained after extraction with ethanol show a light brownish yellow color; (b) in the figure shows the ammonium sulfate crystals obtained after extraction with DMSO, which are basically pure white.

[0068] As a commonly used solvent, ethanol can partially extract the organic matter in the glutamic acid fermentation tail liquor. However, due to limitations in its polarity, solubility, etc., a certain amount of organic matter still remains in the ammonium sulfate crystals, resulting in a yellowish color of the crystals. Thus, the extraction efficiency of ethanol in this system is not complete.

[0069] In contrast, DMSO has a higher polarity and stronger solubility, and can more fully dissolve and carry away the organic matter in the tail liquor. Under the same operating conditions, the ammonium sulfate crystals obtained after extraction with DMSO contain almost no organic impurities and show an almost pure white appearance, indicating that DMSO has better extraction performance in this system.

[0070] By comprehensively comparing the extraction effects of the two solvents, although ethanol is widely used and has a low cost in industrial production, it has certain limitations in removing organic impurities from the glutamic acid fermentation tail liquor; while DMSO can achieve more efficient extraction of organic matter, making the ammonium sulfate crystals more pure, providing a better choice for subsequent determination of organic matter content and even whole-component analysis.

[0071] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A method for extracting and determining the content of organic matter in glutamic acid fermentation tail liquid, characterized in that: The following steps are involved: a) pre-treating the glutamate fermentation tail liquor; b) measuring the density of the tail liquid; c) mixing the tail liquid with an extractant; d) separating the mixed solution to obtain a filtrate containing organic matter; e) drying a portion of the filtrate and weighing the mass of the residue after drying; f) Calculate the organic matter content based on the weighing data and the density.

2. The method according to claim 1, characterized in that The pretreatment step comprises: taking 50 mL of glutamic acid fermentation tail liquid, filtering it using a Buchner funnel and a 100-mesh nylon mesh, collecting the filtrate, and transferring the filtrate to a precision measuring cylinder.

3. The method according to claim 1, characterized in that The density is determined by calculating the weighing data and volume data of the filtrate, and the unit of density is g·cm-3.

4. The method according to claim 1, characterized in that The mixing step comprises: accurately measuring 10 mL of glutamic acid fermentation tail liquid with a pipette and placing it in a 25 mL colorimetric tube, then accurately measuring 1-10 mL of extractant with a pipette and adding it into the colorimetric tube, tightening the stopper of the colorimetric tube and shaking for 1-30 minutes.

5. The method according to claim 1, characterized in that The separation step comprises: filtering the mixed solution by using a filter medium and a filter device, washing the inner wall and the tube plug of the colorimetric tube with 1 to 5 mL of an extractant, filtering the washing liquid together to obtain a wet filter residue and a filtrate; after stopping the suction filtration, the filtrate is accurately measured with a measuring cylinder as an organic extract.

6. The method according to claim 1, characterized in that The drying and weighing steps include: taking a clean and dry glass culture dish, weighing the mass of the culture dish m0 on a balance with an accuracy of 0.0001g, using a pipette with an accuracy of 0.1mL to draw a filtrate approximately equal to 1 / 10 (rounded to one decimal place) of the total volume of the filtrate into the glass culture dish, weighing the mixed mass as m1, placing the glass culture dish in an 80°C electric constant temperature blast drying oven to dry to constant weight, cooling to room temperature, weighing the mass as m2, and calculating the mass according to the formula Calculate the organic matter content.

7. An extractant for use in the method according to claim 1, characterized in that The extractant is one of dimethyl sulfoxide, N,N-dimethylformamide, 1,4-dioxane, methanol, acetic acid and phenol, or a mixture of several of them.

8. The determination method and extractant as described in any one of claims 1 to 7 can be used for the extraction and content determination of organic matter in glutamate granular fertilizer.

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