A method for recycling organic reagents during the pretreatment process of dioxins

Abstract

The present invention discloses a method for recycling organic reagents during the pretreatment of dioxins, belonging to the technical field of waste liquid recycling and treatment. The key points of its technical solution are the method for recycling organic reagents during the pretreatment of dioxins, including the following recycling steps: S1. Add a dispersion purification package to the organic reagent waste liquid and shake it. Stuff glass wool into a glass funnel, add anhydrous magnesium sulfate, and filter the solid substances. The dispersion purification package is composed of sulfuric acid silica gel and Florisil. The sulfuric acid silica gel is prepared by mixing column chromatography silica gel activated under the condition of 550 ± 5 °C with concentrated sulfuric acid, and the Florisil is obtained after being activated under the condition of 550 ± 5 °C; S2. Perform rotary evaporation on the filtrate obtained in step S1 twice and then collect the organic reagents. The recycling method can reduce the consumption of toluene and n-hexane by 90%, and can significantly reduce the expenditure on pretreatment reagents for dioxin detection.

Description

Technical Field

[0001] The present invention relates to the technical field of waste liquid recovery and treatment, and in particular to a method for recovering organic reagents during the pretreatment of dioxins. Background Art

[0002] Dioxins are a general term for some chlorinated polynuclear aromatic compounds. When detecting dioxins, two pretreatment processes of extraction and purification are required. A large amount of n-hexane and toluene are consumed during the pretreatment process. Depending on the extraction and purification methods, each sample is expected to consume 300 - 1000 mL of n-hexane and 140 - 500 mL of toluene. Moreover, different operation methods consume different amounts of organic reagents. For example, Soxhlet extraction consumes more organic reagents than ASE extraction in the extraction step, and the automatic purification scheme consumes more organic reagents than the manual purification scheme with a hand-packed purification column in the purification step. However, no matter which scheme is selected, it is impossible to avoid the consumption of a large amount of organic reagents and the generation of a large amount of waste liquid, which has caused great pressure on both the laboratory reagent cost and the waste liquid treatment cost, and has also caused a greater negative impact on environmental protection.

[0003] After years of practice and improvement, the extraction and purification schemes of dioxins have basically reached an optimal level in terms of reagent selection and dosage. Therefore, the space for reducing the dosage is extremely small, and the dosage of reagents will directly affect the detection results. Therefore, the recycling of reagents is the best solution to reduce the laboratory reagent cost. Therefore, it is urgent to establish a method for recovering toluene and n-hexane from the waste liquid of dioxin pretreatment to solve the current cost and environmental protection problems. Summary of the Invention

[0004] In order to solve the problems in the prior art, the present invention provides a method for recovering organic reagents during the pretreatment of dioxins, which can reduce the consumption of toluene and n-hexane by 90%, can significantly reduce the expenditure on the pretreatment reagents for dioxin detection. For a dioxin laboratory with an annual sample volume of 10,000 batches, it is expected to reduce the reagent cost expenditure by 300,000 - 1,000,000 yuan, and can reduce the waste liquid treatment cost by 3960 - 13500 L. Under normal circumstances, if the water remover magnesium sulfate is recycled, only 1.5 g of solid waste will be generated while reducing the generation of 1 L of organic waste liquid, which is relatively friendly to the environment.

[0005] A method for recovering organic reagents during the pretreatment of dioxins provided by the present invention adopts the following technical scheme:

[0006] A method for recovering organic reagents during the pretreatment of dioxins includes the following recovery steps:

[0007] S1. Add a dispersion purification package to the organic reagent waste liquid and shake it. Stuff glass wool into a glass funnel, add anhydrous magnesium sulfate, and filter the solid matter. The dispersion purification package is composed of sulfuric acid silica gel and Florisil. The sulfuric acid silica gel is prepared by mixing column chromatography silica gel activated under the condition of 550 ± 5 °C with concentrated sulfuric acid. The Florisil is obtained after being activated under the condition of 550 ± 5 °C;

[0008] S2. Perform rotary evaporation on the filtrate obtained in step S1 twice and collect the organic reagent.

[0009] In a preferred embodiment, the concentration of the dispersion purification package in the organic reagent waste liquid is 1.4 - 1.6 g / L.

[0010] In a preferred embodiment, the weight ratio of the sulfuric acid silica gel to the Florisil is 1:(0.8 - 1.2).

[0011] In a preferred embodiment, the mass concentration of concentrated sulfuric acid in the sulfuric acid silica gel is 20 - 40 wt%.

[0012] In a preferred embodiment, the mass concentration of concentrated sulfuric acid in the sulfuric acid silica gel is 30 - 40 wt%.

[0013] In a preferred embodiment, the column chromatography silica gel is mixed with concentrated sulfuric acid after being activated under the condition of 550 ± 5 °C for 12 ± 0.5 h.

[0014] In a preferred embodiment, the Florisil is obtained after being activated under the condition of 550 ± 5 °C for 24 ± 0.5 h.

[0015] In a preferred embodiment, the organic reagent waste liquid is toluene waste liquid or n - hexane waste liquid; the conditions for the first rotary evaporation of the toluene waste liquid are rotary evaporation at 60 ± 2 °C and 180 - 200 hPa for 10 - 15 min, and the conditions for the second rotary evaporation start at 60 ± 2 °C and 180 - 220 hPa, and the pressure is reduced to 100 - 120 hPa within 2 min.

[0016] In a preferred embodiment, the conditions for the first rotary evaporation of the n - hexane waste liquid are rotary evaporation at 60 ± 2 °C and 480 - 500 hPa for 10 ± 2 min, and the conditions for the second rotary evaporation start at 60 ± 2 °C and 480 - 500 hPa, and the pressure is reduced to 300 - 330 hPa within 5 min.

[0017] In summary, the present invention has the following beneficial effects:

[0018] When the method of the present application is used for the recovery of organic reagents, the consumption of toluene and n-hexane can be reduced by 90%, and the expenditure on the pretreatment reagents for dioxin detection can be significantly reduced. For a dioxin laboratory with an annual sample volume of 10,000 batches, it is estimated that the reagent cost can be reduced by 300,000 - 1,000,000 yuan. For a dioxin laboratory with an annual sample volume of 10,000 batches, it is estimated that the waste liquid treatment cost can be reduced by 3,960 - 13,500 L. In addition, the addition of the dispersion purification package can efficiently remove most of the impurities in toluene and n-hexane, and no dioxin-like substances are detected after concentrating toluene and n-hexane by 10,000 times.

[0019] After the column chromatography silica gel and Florisil in the dispersion purification package of the present application are purified at high temperature, the organic substances and the moisture contained in the column chromatography silica gel and Florisil can be removed, thereby improving the adsorption effect on impurities.

[0020] Sulfuric acid in sulfuric acid silica gel has a sulfonation effect, and silica gel has an adsorption effect. After sulfuric acid and silica gel are used in combination, the organic impurities can be completely sulfonated, and the adsorption of organic impurities by silica gel can be improved. However, when the content of sulfuric acid is relatively low, partial sulfonation of organic impurities will occur and they cannot be adsorbed by silica gel. When the sulfuric acid content exceeds 40%, it is easy to cause carbonization of impurities, which will cause potential adverse effects. Moreover, the sulfonated impurities need to be adsorbed by silica gel. The higher the sulfuric acid content, the lower the silica gel content under the same mass, and the dosage needs to be increased, which will affect the cost and the generation of solid waste. Therefore, when the mass concentration of sulfuric acid in sulfuric acid silica gel is in the range of 20 - 40%, the adsorption effect of silica gel on organic impurities can be effectively guaranteed, and at the same time, the recovery cost can be relatively low. Description of the Drawings

[0021] Figures 1 - 10 It is the detection spectrum of Example 1 of the present application.

[0022] Figures 11 - 20 It is the detection spectrum of Comparative Example 3 of the present application. Detailed Description of the Invention

[0023] The present invention will be further described in detail below with reference to the embodiments. All reagents not indicating the manufacturer can be conventional reagent products obtained through commercial purchase.

[0024] The toluene waste liquid includes toluene extraction liquid (Soxhlet extraction and ASE extraction), about 60 - 350 mL of samples, and toluene elution liquid generated during the reverse elution of the activated carbon silica gel column, about 80 - 150 mL of samples. Since these two parts of toluene have been concentrated by rotary evaporation, most of the non-volatile impurities have been removed, and the main impurities are water and volatile substances in the samples, as well as a small amount of dioxin and dioxin internal standard substances that may exist.

[0025] Example 1

[0026] A method for recycling organic reagents in the pretreatment process of dioxins. The toluene generated in the pretreatment steps is recycled according to the following steps:

[0027] S1. Combine the toluene waste liquid. If there are obvious water droplets at the bottom or on the wall of the container, add sufficient anhydrous magnesium sulfate and shake appropriately until there are no obvious water droplets. Stuff a small amount of glass wool into a glass funnel, add 5 g of anhydrous magnesium sulfate, and filter out all the solid substances used;

[0028] S2. Add 6 g of a dispersion purification package to 4 L of the toluene waste liquid and shake well for 15 min. Stuff a small amount of glass wool into a glass funnel, add 5 g of anhydrous magnesium sulfate, and filter all the solid substances. The dispersion purification package consists of sulfuric acid silica gel and Florisil with a weight ratio of 1:1. The sulfuric acid silica gel is prepared by activating column chromatography silica gel at 550 ± 5 °C for 12 h and then mixing it with concentrated sulfuric acid. The mass concentration of sulfuric acid in the sulfuric acid silica gel is 20 wt%. The Florisil is obtained by activating it at 550 ± 5 °C for 24 h;

[0029] S3. Add the filtrate obtained in step S1 to a round-bottom flask and perform the first rotary evaporation for 10 min at 60 °C and 180 hPa to remove volatile impurities. During the rotary evaporation, pay attention that there should be no obvious boiling. Discard the liquid in the collection bottle and replace the collection bottle;

[0030] S4. Starting from 60 °C and 180 hPa, gradually reduce the pressure to 100 hPa within 2 min and perform the second rotary evaporation for 35 min to evaporate about 97% of the liquid. During the rotary evaporation, pay attention that there should be no obvious boiling to avoid drying out the liquid. The liquid remaining in the round-bottom flask contains most of the non-volatile impurities, including dioxins and their corresponding internal standard substances as well as a small amount of toluene. Discard the liquid remaining in the round-bottom flask, and the final product obtained in the collection bottle is toluene. Take 100 mL of the final product, concentrate it to 10 μL and then analyze it by machine. There are no dioxin and internal standard peaks, that is, the toluene obtained in the collection bottle is a qualified product. Transfer it to a clean brown glass bottle for storage. The test results are as Figures 1 - 10 shown. The specific substances in the spectrogram are as follows:

[0031]

[0032] Example 2

[0033] A method for recycling organic reagents in the pretreatment process of dioxins. The toluene generated in the pretreatment steps is recycled according to the following steps:

[0034] S1. Combine the toluene waste liquid. If there are obvious water droplets at the bottom or on the wall of the container, add sufficient anhydrous magnesium sulfate, shake appropriately until there are no obvious water droplets, stuff a small amount of glass wool into a glass funnel, add 5 g of anhydrous magnesium sulfate, and filter off the solid substances used;

[0035] S2. Add 5.6 g of the dispersion purification package to 4 L of the toluene waste liquid, shake well for 15 min, stuff a small amount of glass wool into a glass funnel, add 5 g of anhydrous magnesium sulfate, and filter all the solid substances. The dispersion purification package consists of silica gel sulfate and Florisil with a weight ratio of 1:1. The silica gel sulfate is prepared by mixing column chromatography silica gel activated at 550 ± 5 °C for 11.5 h with concentrated sulfuric acid, and the mass concentration of sulfuric acid in the silica gel sulfate is 20 wt%. The Florisil is obtained after being activated at 550 ± 5 °C for 24.5 h;

[0036] S3. Add the filtrate obtained in step S1 to a round-bottom flask, perform the first rotary evaporation at 60 °C and 200 hPa for 15 min to remove volatile impurities. Note that obvious boiling should not occur during rotary evaporation. Discard the liquid in the collection bottle and replace the collection bottle;

[0037] S4. Starting from 60 °C and 200 hPa, gradually reduce the pressure to 120 hPa within 2 min and perform the second rotary evaporation for 35 min to evaporate about 97% of the liquid. Note that obvious boiling should not occur during rotary evaporation to avoid drying out the liquid. The liquid remaining in the round-bottom flask contains most of the refractory impurities, including dioxins and their corresponding internal standard substances as well as a small amount of toluene. Discard the liquid remaining in the round-bottom flask, and the final product obtained in the collection bottle is toluene. Take 100 mL of the final product, concentrate it to 10 μL and then analyze it by machine. No dioxin and its internal standard peaks appear, that is, the toluene obtained in the collection bottle is a qualified product. Transfer it to a clean brown glass bottle for storage, and the test result is roughly the same as the spectrogram in Example 1.

[0038] Example 3

[0039] A method for recycling organic reagents during the pretreatment of dioxins. The toluene generated in the pretreatment steps is recycled according to the following steps:

[0040] S1. Combine the toluene waste liquid. If there are obvious water droplets at the bottom or on the wall of the container, add sufficient anhydrous magnesium sulfate, shake appropriately until there are no obvious water droplets, stuff a small amount of glass wool into a glass funnel, add 5 g of anhydrous magnesium sulfate, and filter off the solid substances used;

[0041] S2. Add 6.4 g of the dispersion and purification package to 4 L of toluene waste liquid, shake well for 15 min, stuff a small amount of glass wool into a glass funnel, add 5 g of anhydrous magnesium sulfate, and filter all solid substances. The dispersion and purification package consists of silica sulfate and Florisil with a weight ratio of 1:1. Silica sulfate is prepared by activating column chromatography silica gel at 550 ± 5 °C for 12.5 h and then mixing it with concentrated sulfuric acid. The mass concentration of sulfuric acid in silica sulfate is 20 wt%. Florisil is obtained by activating it at 550 ± 5 °C for 23.5 h;

[0042] S3. Add the filtrate obtained in step S1 to a round-bottom flask and carry out the first rotary evaporation for 15 min at 60 °C and 200 hPa to remove volatile impurities. Pay attention not to have obvious boiling during rotary evaporation, discard the liquid in the collection flask, and replace the collection flask;

[0043] S4. Starting from 60 °C and 200 hPa, gradually reduce the pressure to 120 hPa within 2 min and carry out the second rotary evaporation for 35 min to evaporate about 97% of the liquid. Pay attention not to have obvious boiling during rotary evaporation to avoid the liquid being completely evaporated. The liquid remaining in the round-bottom flask contains most of the non-volatile impurities, including dioxins and their corresponding internal standard substances as well as a small amount of toluene. Discard the liquid remaining in the round-bottom flask, and the final product obtained in the collection flask is toluene. Take 100 mL of the final product, concentrate it to 10 μL and then analyze it on the machine. No dioxin and its internal standard peaks appear, that is, the toluene obtained in the collection flask is a qualified product, transfer it to a clean brown glass bottle for storage, and the detection result is roughly the same as the spectrogram in Example 1.

[0044] Example 4

[0045] A method for recycling organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the mass concentration of sulfuric acid in silica sulfate is 30%, and the others are the same as in Example 1. After detection, no dioxin and its internal standard peaks appear, and the detection result is roughly the same as the spectrogram in Example 1.

[0046] Example 5

[0047] A method for recycling organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the mass concentration of sulfuric acid in silica sulfate is 40%, and the others are the same as in Example 1. After detection, no dioxin and its internal standard peaks appear, and the detection result is roughly the same as the spectrogram in Example 1.

[0048] Example 6

[0049] A method for recycling organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the weight ratio of sulfuric acid silica gel to Florisil is 1:0.8, and the others are the same as in Example 1. After detection, no dioxin and its internal standard peaks appear, and the detection results are roughly the same as the spectrogram in Example 1.

[0050] Example 7

[0051] A method for recycling organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the weight ratio of sulfuric acid silica gel to Florisil is 1:1.2, and the others are the same as in Example 1. After detection, no dioxin and its internal standard peaks appear, and the detection results are roughly the same as the spectrogram in Example 1.

[0052] The method for recycling the n-hexane waste liquid generated in the purification step is the same as that for recycling toluene, and the following examples are used for illustration.

[0053] For about 200 - 1000 mL samples of the n-hexane waste liquid (including the n-hexane used for activating and eluting the purification column) generated in the purification step, the following steps are used for recycling.

[0054] Example 8

[0055] A method for recycling organic reagents during the pretreatment of dioxins, comprising the following steps:

[0056] S1. Combine the n-hexane waste liquid generated multiple times, add 5.6 g of the dispersion purification package to 4 L of the n-hexane waste liquid, shake well for 15 min, stuff a small amount of glass wool into a glass funnel, and add 5 g of anhydrous magnesium sulfate, and filter all solid substances. The dispersion purification package consists of sulfuric acid silica gel and Florisil with a weight ratio of 1:1. The sulfuric acid silica gel is prepared by mixing column chromatography silica gel activated at 550 ± 5 °C for 12 h with concentrated sulfuric acid, and the mass concentration of sulfuric acid in the sulfuric acid silica gel is 20 wt%. The Florisil is obtained after being activated at 550 ± 5 °C for 24 h;

[0057] S2. Add the filtrate obtained in step S1 to a round-bottom flask, perform the first rotary evaporation for 10 min at 60 °C and 480 hPa to remove volatile impurities. During rotary evaporation, pay attention that there should be no obvious boiling, discard the liquid in the collection bottle, and replace the collection bottle;

[0058] S3. Starting from 60 °C and 480 hPa, gradually reduce the pressure to 300 hPa within 5 minutes for the second rotary evaporation for 35 minutes, evaporating approximately 97% of the liquid. During the rotary evaporation, ensure that there is no obvious boiling to avoid the liquid being completely evaporated. The liquid remaining in the round-bottom flask contains most of the non-volatile impurities, including dioxins and their corresponding internal standard substances, as well as a small amount of n-hexane. Discard the liquid remaining in the round-bottom flask, and the final product obtained in the collection flask is n-hexane. Take 100 mL of the final product, concentrate it to 10 μL, and then analyze it on the machine. There are no dioxin and its internal standard peaks, indicating that the n-hexane obtained in the collection flask is a qualified product. Transfer it to a clean brown glass bottle for storage, and the test results are roughly the same as the spectrogram in Example 1.

[0059] Comparative Example 1

[0060] A method for recovering organic reagents during the pretreatment of dioxins, which is different from Example 1 in that diatomaceous earth is used to replace florisil in the dispersion purification package in equal amounts, and the rest are the same as in Example 1. After detecting the toluene obtained, interference peaks appear in the spectrogram, which are confirmed to be dioxin and its internal standard peaks, and polychlorinated biphenyls.

[0061] Comparative Example 2

[0062] A method for recovering organic reagents during the pretreatment of dioxins, which is different from Example 1 in that silver nitrate silica gel is used to replace sulfuric acid silica gel in the dispersion purification package in equal amounts, and the concentration of silver nitrate in the silver nitrate silica gel is 20 wt%. The rest are the same as in Example 1. After detecting the toluene obtained, interference peaks appear in the spectrogram, which are confirmed to be polycyclic aromatic hydrocarbon substances.

[0063] Comparative Example 3

[0064] A method for recovering organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the dispersion purification package is composed of silver nitrate silica gel and diatomaceous earth with a weight ratio of 1:1, and the concentration of silver nitrate in the silver nitrate silica gel is 20 wt%. The rest are the same as in Example 1. After detecting the toluene obtained, interference peaks appear in the spectrogram, which are confirmed to be polycyclic aromatic hydrocarbon substances, polychlorinated biphenyls, and dioxin and its internal standard substances. The test results are as Figures 11 - 20 shown.

[0065] Comparative Example 4

[0066] A method for recovering organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the mass concentration of sulfuric acid in the sulfuric acid silica gel is 15 wt%. The rest are the same as in Example 1. After detecting the toluene obtained, interference peaks appear in the spectrogram, which are confirmed to be polycyclic aromatic hydrocarbon substances.

[0067] Comparative Example 5

[0068] A method for recovering organic reagents during the pretreatment of dioxins, which is different from Example 1 in that the mass concentration of sulfuric acid in sulfuric acid silica gel is 45 wt%, and the others are the same as in Example 1. After detecting the toluene obtained therefrom, more impurity peaks appear in the spectrogram.

[0069] The embodiments of this specific implementation manner are all preferred embodiments of the present invention, and do not limit the protection scope of the present invention accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for recycling organic reagents in the pretreatment process of dioxins, characterized in that, It includes the following recovery steps: S1. Add a dispersion purification package to the organic reagent waste liquid and shake it. Stuff glass wool into a glass funnel, add anhydrous magnesium sulfate, and filter the solid substances. The dispersion purification package is composed of sulfuric acid silica gel and Florisil. The sulfuric acid silica gel is prepared by mixing column chromatography silica gel activated under the condition of 550 ± 5 °C with concentrated sulfuric acid. The mass concentration of concentrated sulfuric acid in the sulfuric acid silica gel is 20 - 40 wt%; the Florisil is obtained after being activated under the condition of 550 ± 5 °C; the organic reagent waste liquid is toluene waste liquid or n-hexane waste liquid. S2. Perform rotary evaporation on the filtrate obtained in step S1 twice and then collect the organic reagent.

2. The recovery method of the organic reagent in the pretreatment process of dioxin according to claim 1, wherein: The concentration of the dispersion purification package in the organic reagent waste liquid is 1.4 - 1.6 g / L.

3. A method for recycling organic reagents during the pretreatment of dioxins, according to claim 1, characterized in that: The weight ratio of the sulfuric acid silica gel to the Florisil is 1:(0.8 - 1.2).

4. The recovery method of the organic reagent in the pretreatment process of dioxin according to claim 1, wherein: The mass concentration of concentrated sulfuric acid in the sulfuric acid silica gel is 30 - 40 wt%.

5. The recovery method of the organic reagent in the pretreatment process of dioxin according to claim 1, wherein: The column chromatography silica gel is mixed with concentrated sulfuric acid after being activated under the condition of 550 ± 5 °C for 12 ± 0.5 h.

6. A method for recovering organic reagents in the pretreatment process of dioxins, according to claim 1, characterized in that: The Florisil is obtained after being activated under the condition of 550 ± 5 °C for 24 ± 0.5 h.

7. The recovery method of organic reagents in the pretreatment process of dioxins according to claim 1, characterized in that: The conditions for the first rotary evaporation of the toluene waste liquid are rotary evaporation at 60 ± 2 °C and 180 - 200 hPa for 10 - 15 min, and the conditions for the second rotary evaporation start at 60 ± 2 °C and 180 - 220 hPa, and the pressure is reduced to 100 - 120 hPa within 2 min.

8. A method for recovering organic reagents during the pretreatment of dioxins, according to claim 1, characterized in that: The conditions for the first rotary evaporation of the n-hexane waste liquid are rotary evaporation at 60 ± 2 °C and 480 - 500 hPa for 10 ± 2 min, and the conditions for the second rotary evaporation start at 60 ± 2 °C and 480 - 500 hPa, and the pressure is reduced to 300 - 330 hPa within 5 min.

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