Method for removing various undesirable impurities in mixed tocopherol through continuous countercurrent extraction

Abstract

The invention discloses a method for removing various undesirable impurities in mixed tocopherol through continuous countercurrent extraction, and particularly relates to the technical field of chemical engineering and natural product separation. The method comprises the steps of light phase and heavy phase configuration and continuous countercurrent extraction. According to the method, n-hexane-dimethyl sulfoxide (DMSO) and the like are used as a two-phase solvent to serve as an extracting agent, the toxic and harmful impurities are enriched in DMSO by utilizing interaction between the extracting agent and impurity molecules containing benzene ring conjugated pi bonds, and meanwhile, a continuous countercurrent extraction process is adopted, so that the extraction efficiency is improved. Various residual indexes of benzopyrene, zearalenone and pesticide residues in the mixed tocopherol reach international standards, and the product yield can reach 97% or above.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering and natural product separation, and in particular to a method for removing multiple undesirable impurities in mixed tocopherols by continuous countercurrent extraction. Background Art

[0002] Plant deodorized distillate (DD oil for short) is a by-product of the vegetable oil refining process, which contains a variety of trace toxic and harmful impurities, such as polycyclic aromatic hydrocarbons, zearalenone, pesticide residues, etc.; polycyclic aromatic hydrocarbons (PAHs) are a class of widely existing organic pollutants, among which benzopyrene, the most carcinogenic, can cause human DNA damage and then develop into cancer; zearalenone, also known as F-2 toxin, is a heat-stable non-steroidal fungal toxin with estrogenic properties, which can cause abnormal reproductive function in animals and thus trigger a series of health problems such as cell apoptosis, teratogenesis, DNA damage, and immune system disorders; pesticide residues are a general term for dozens of toxic and harmful substances including pyrethroid compounds, anthraquinone, and propiconazole.

[0003] In the process of conventional DD oil separation and purification of mixed tocopherols, these undesirable impurities cannot be effectively separated from mixed tocopherols. Therefore, as the content of mixed tocopherols continues to increase, these toxic and harmful impurities are also continuously enriched. The content of benzopyrene in the enriched mixed tocopherols can generally reach more than 200 ppb (μg / kg), while the international index for benzopyrene in oils and fats requires less than 1 ppb. The content of zearalenone in the enriched mixed tocopherols can reach several thousand or even tens of thousands of ppb, and the EU limits the content of zearalenone in oils and fats to less than 400 ppb. There are many kinds of pesticide residue compounds, such as the average level of pyrethroid pesticide residues reaching hundreds of ppb, and tebuconazole, anthraquinone, etc. also have dozens or even hundreds of ppb residues. Therefore, extensive research and process development have also been carried out on the removal of various toxic and harmful impurities in mixed tocopherols.

[0004] At present, the more effective methods for removing benzopyrene from mixed tocopherols mainly revolve around adsorption removal by adsorbents, solvent extraction, silica gel column chromatography and other methods. Among them, the use of adsorbents to adsorb benzopyrene in oils and fats is a more common removal method in industrialization. The adsorbents used include activated carbon, kaolin, activated white clay, etc. After mixed tocopherols are adsorbed by activated carbon, the benzopyrene content in them can also be effectively reduced to below 2ppb; the solvent extraction method uses acetonitrile, diformamide-cyclohexane-water, cyclopentane-n-hexane-water and other two-phase or three-phase solvent systems for multiple extractions to achieve the purpose of removing benzopyrene from mixed tocopherols; silica gel column chromatography uses the molecular polarity difference between mixed tocopherols and benzopyrene for removal; and zearalenone is usually removed by high-temperature steam deodorization or activated carbon adsorption. Pesticide residues will be gradually removed during the purification process of mixed tocopherols, but some will still remain in the final product, and the residue amount cannot meet the export standards.

[0005] In the existing removal methods, although activated carbon can effectively remove benzopyrene and zearalenone from mixed tocopherols, the activated carbon that reaches a saturated state after multiple adsorptions cannot be effectively recycled, and the amount of activated carbon used in industrialization is large, so a large amount of solid hazardous waste will be generated, affecting the environment. At the same time, activated carbon will also adsorb a small amount of mixed tocopherols, resulting in a decrease in product yield; although the currently used solvent extraction process can remove part of benzopyrene, the extraction removal rate is not high due to the difference in solubility, and the amount of solvent is large, which is not suitable for industrial production, and there is also a problem of loss of mixed tocopherol yield; although silica gel column chromatography can obtain a higher mixed tocopherol yield, this method has strict process control, small processing volume, large solvent consumption, and unstable benzopyrene removal rate; although zearalenone can be effectively removed after high-temperature steam deodorization, mixed tocopherols are easily oxidized under high temperature conditions and lose yield, and the temperature control in the deodorization step is also relatively harsh, which is easy to produce other harmful substances such as glycidol.

[0006] The existing purification devices and methods are mainly used to separate mixed tocopherols from the deodorized distillate of vegetable oil. However, after the tocopherols are separated, there is no method on the market to remove the various trace toxic and harmful impurities that are enriched. Summary of the invention

[0007] To this end, the present invention provides a method for removing multiple undesirable impurities in mixed tocopherols by continuous countercurrent extraction to solve the above-mentioned problems.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] According to the present invention, a method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction is provided, the method comprising:

[0010] Step 1: Configuration of light phase and heavy phase

[0011] Mixing and dissolving mixed tocopherols with a light phase solution to form an extraction light phase; using a blank extract as an extraction heavy phase;

[0012] Step 2: Continuous countercurrent extraction

[0013] The light phase and heavy phase are introduced into the annular mixing zone formed between the drum and the shell through the light phase inlet and the heavy phase inlet respectively. With the help of the rotation of the drum, the two phases are quickly mixed and dispersed through the turbine disc and the impeller. The two-phase solution is fully transferred, completing the mixing and mass transfer process to obtain a mixed solution.

[0014] The mixed liquid enters the drum under the action of the turbine disc. In the compartment area formed by the Fu plate, the mixed liquid quickly rotates synchronously with the drum. Under the action of centrifugal force, the heavy phase liquid with a large specific gravity gradually moves away from the center of the drum and approaches the drum wall during the upward flow; the light phase liquid with a small specific gravity gradually moves away from the drum wall and approaches the center. The clarified two-phase liquid finally passes through the heavy phase weir plate and the light phase weir plate to enter the heavy phase collection chamber and the light phase collection chamber respectively, and flows out of the system from the light phase outlet and the heavy phase outlet, completing the two-phase separation process, and obtaining tocopherol with undesirable impurities extracted.

[0015] As an example, the extraction light phase and the extraction heavy phase of the present invention enter the extraction system from the light phase inlet of the first stage and the heavy phase inlet of the last stage respectively, and the flow rate is controlled at 3-8 mL / min, more preferably 5 mL / min.

[0016] Further, in step 1, the light phase solution is normal hexane and / or cyclohexane. In this section, the light phase solution can be selected from normal hexane or cyclohexane alone, or a mixture of normal hexane and cyclohexane.

[0017] Furthermore, in the step 1, the ratio of the mixed tocopherol raw material to the light phase solution is 1:3-5.

[0018] Furthermore, the ratio of the mixed tocopherol raw material to the light phase solution is 1:3.

[0019] Furthermore, in step 1, the blank extract is one or more of sulfolane, 2,4-dimethylsulfolane, and dimethyl sulfoxide (DMSO).

[0020] Furthermore, the blank extract is sulfolane and / or dimethyl sulfoxide (DMSO).

[0021] Furthermore, the blank extract is dimethyl sulfoxide (DMSO).

[0022] Furthermore, in the step 1, the ratio of the mixed tocopherol raw material to the blank extract is 1:3-5.

[0023] Furthermore, the ratio of the mixed tocopherol raw material to the blank extract is 1:4.

[0024] Furthermore, in step 2, the number of continuous countercurrent extraction stages is 5-10. As an example, each stage uses a jacket to control the temperature to 40°C-60°C, preferably 50°C.

[0025] The present invention utilizes a continuous countercurrent extraction process, and the removal of benzopyrene and zearalenone in mixed tocopherols can reach the residual amount that can be achieved after intermittent extraction, but the recovery rate of mixed tocopherols can be greatly improved, and the mixed tocopherol yield can reach 97-98%. This is because the extraction phase is repeatedly back-extracted by the raffinate phase with a low mixed tocopherol concentration during the countercurrent extraction process, thereby recovering the mixed tocopherols in the extraction phase to the maximum extent.

[0026] The present invention has the following advantages:

[0027] The invention uses a continuous countercurrent two-phase solvent extraction process to simultaneously remove multiple toxic and harmful impurities such as benzopyrene, zearalenone and pesticide residues in mixed tocopherols, and ensures that the yield of mixed tocopherols reaches a high level.

[0028] The invention uses n-hexane-dimethyl sulfoxide (DMSO) and the like as a two-phase solvent and an extractant, utilizes the extractant to interact with the impurity molecules containing the conjugated π bonds of the benzene ring, so that the above toxic and harmful impurities are enriched in DMSO, and simultaneously adopts a continuous countercurrent extraction process, so that not only the various residual indicators of benzopyrene, zearalenone and pesticide residues in the mixed tocopherols meet the international standards, but also the product yield can reach more than 97%.

[0029] The removal rate of the invention is stable: after multi-stage continuous countercurrent extraction, the residual amount of benzopyrene in the mixed tocopherols can be stably less than 1 ppb, the residual amount of zearalenone in the mixed tocopherols can be stably less than 200 ppb, and various indicators of pesticide residues meet the export standards; the mixed tocopherols of the invention have a high yield: the mixed tocopherols have a small distribution coefficient in the extractant, and the mixed tocopherols yield can reach 97-98% after multi-stage countercurrent extraction; the extraction process of the invention has mild conditions, a large processing volume, continuous production, the solvent can be recycled, and the process is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0031] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0032] Figure 1 A system for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction provided in Example 1 of the present invention;

[0033] In the figure, 1-light phase inlet; 2-light phase outlet; 3-heavy phase collecting chamber; 4-heavy phase outlet; 5-light phase collecting chamber; 6-heavy phase inlet; 7-compartment area; 8-drum; 9-turbine disc; 10-foil plate; 11-shell; 12-heavy phase weir plate; 13-light phase weir plate; 14-baffle plate. DETAILED DESCRIPTION

[0034] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] A system for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction Figure 1 As shown, including:

[0037] Light phase inlet 1, light phase outlet 2, heavy phase collecting chamber 3, heavy phase outlet 4, light phase collecting chamber 5, heavy phase inlet 6, compartment area 7, drum 8, turbine disc 9, plate 10, shell 11, heavy phase weir plate 12, light phase weir plate 13 and baffle plate 14;

[0038] The light phase inlet 1 is communicated with the annular gap type mixing zone formed between the first stage drum 8 and the shell 11, and the heavy phase inlet 6 is communicated with the annular gap type mixing zone formed between the last stage drum 8 and the shell 11; the mixture zone is directly connected to the compartment area 7, and the compartment area 7 is provided with a baffle plate 10 and a baffle plate 14 (to prevent the mixed liquid from returning to the annular gap type mixing zone). The upper part of the compartment area 7 is connected to the light phase collecting chamber 5 through the light phase weir plate 13, and the other end is connected to the heavy phase collecting chamber 3 through the heavy phase weir plate 12. The light phase collecting chamber 5 is connected to the light phase outlet 2, and the heavy phase collecting chamber 3 is connected to the heavy phase outlet 4.

[0039] Specifically, the extracted light phase enters the annular gap type mixing zone formed between the first-stage drum 8 and the shell 11 through the light phase inlet 1 of the first stage, and the extracted heavy phase enters the annular gap type mixing zone formed between the last-stage drum 8 and the shell 11 through the heavy phase inlet 6 of the last stage. With the help of the rotation of the drum 8, the two phases are quickly mixed and dispersed through the turbine disk 9 and the impeller on the turbine disk 9, and the two-phase solution is fully mass transferred, completing the mixing and mass transfer process to obtain a mixed solution.

[0040] The mixed liquid enters the drum 8 and the compartment area 7 formed by the weir plate 10 under the action of the turbine disk 9. The mixed liquid quickly rotates synchronously with the drum 8. Under the action of centrifugal force, the heavy phase liquid with a large specific gravity gradually moves away from the center of the drum and approaches the drum wall during the upward flow; the light phase liquid with a small specific gravity gradually moves away from the drum wall and approaches the center. The clarified two-phase liquid finally passes through the heavy phase weir plate 12 and the light phase weir plate 13 to enter the heavy phase collection chamber 3 and the light phase collection chamber 5 respectively, and flows out of the system from the light phase outlet 2 and the heavy phase outlet 4, completing the two-phase separation process, and obtaining tocopherol after extraction of undesirable impurities.

[0041] Example 2

[0042] The mixed tocopherols were processed using the system of Example 1 as follows:

[0043] 100.5 g of mixed tocopherols (tocopherol content 53.3%, benzopyrene content 319 ppb, zearalenone content 17500 ppb, cypermethrin 412 ppb, bifenthrin 695 ppb, lambda-cyhalothrin 439 ppb, permethrin 439 ppb, tebuconazole 186 ppb, anthraquinone 31 ppb) was weighed and dissolved in 300 mL of n-hexane as a light phase solution, 500 mL of DMSO was used as a heavy phase extractant, the light phase entered the extraction system from the light phase inlet of the first stage centrifugal extractor at a flow rate of 5 mL / min, and the heavy phase was extracted at a flow rate of 5 m The extraction system is entered from the heavy phase inlet of the fifth-stage centrifugal extractor at a flow rate of L / min, and each stage of the centrifugal extractor adopts a jacket to control the temperature to 50°C, and the extraction phase (heavy phase) is collected from the first-stage heavy phase outlet, and DMSO is recovered under reduced pressure for application, and the raffinate phase (light phase) is collected from the fifth-stage light phase outlet, and n-hexane is recovered under reduced pressure for application, and 96.08g of mixed tocopherol concentrate (with a tocopherol content of 54.19%, a yield of 97.20%, a benzopyrene residue of 0.25ppb, an undetectable zearalenone residue, and undetectable types of pesticide residues) is obtained after n-hexane is recovered from the raffinate phase under reduced pressure.

[0044] Example 2

[0045] The mixed tocopherols were processed using the system of Example 1 as follows:

[0046] 75.2 g of mixed tocopherols (tocopherol content 53.3%, benzopyrene content 319 ppb, zearalenone content 17500 ppb, cypermethrin 412 ppb, bifenthrin 695 ppb, lambda-cyhalothrin 439 ppb, permethrin 439 ppb, tebuconazole 186 ppb, anthraquinone 31 ppb) were weighed and dissolved in 215 mL of n-hexane as a light phase solution, 300 mL of DMSO was used as a heavy phase extractant, the light phase entered the extraction system from the light phase inlet of the first stage centrifugal extractor at a flow rate of 5 mL / min, and the heavy phase was extracted at a flow rate of 5 mL / min. The extractant was collected from the heavy phase outlet of the first stage, DMSO was recovered under reduced pressure, and the raffinate phase (light phase) was collected from the light phase outlet of the fifth stage, and n-hexane was recovered under reduced pressure. After n-hexane was recovered from the raffinate phase under reduced pressure, 72.94 g of mixed tocopherol concentrate was obtained (with a tocopherol content of 53.75%, a yield of 97.81%, a benzopyrene residue of 0.42 ppb, an undetectable zearalenone residue, and all kinds of pesticide residues were not detected).

[0047] Example 3

[0048] The mixed tocopherols were processed using the system of Example 1 as follows:

[0049] 101.8 g of mixed tocopherols (tocopherol content 53.3%, benzopyrene content 319 ppb, zearalenone content 17500 ppb, cypermethrin 412 ppb, bifenthrin 695 ppb, lambda-cyhalothrin 439 ppb, permethrin 439 ppb, tebuconazole 186 ppb, anthraquinone 31 ppb) was dissolved in 300 mL of n-hexane as a light phase solution, 400 mL of sulfolane was used as a heavy phase extractant, the light phase entered the extraction system from the light phase inlet of the first stage centrifugal extractor at a flow rate of 5 mL / min, and the heavy phase was extracted at a flow rate of 5 mL / min. / min flow rate from the 6th stage centrifugal extractor heavy phase inlet into the extraction system, each stage centrifugal extractor is jacketed to control the temperature of 50 ° C, and the extraction phase (heavy phase) is collected from the 1st stage heavy phase outlet, and the sulfolane is recovered under reduced pressure for application, and the raffinate phase (light phase) is collected from the 6th stage light phase outlet, and the n-hexane is recovered under reduced pressure for application, and the n-hexane is recovered from the raffinate phase under reduced pressure to obtain 98.98g of mixed tocopherol concentrate (with a tocopherol content of 53.60%, a yield of 97.78%, a benzopyrene residue of 0.21ppb, a zearalenone residue that was not detected, and various types of pesticide residues were not detected).

[0050] Comparative Example 1

[0051] This comparative example provides a method for removing multiple undesirable impurities in mixed tocopherols:

[0052] 100.2 g of mixed tocopherols (tocopherol content: 53.3%, benzopyrene content: 319 ppb, zearalenone content: 17500 ppb) was weighed and dissolved in 300 mL of n-hexane, 500 mL of DMSO was added for extraction, heated in a water bath, the temperature was controlled at 50 ° C, the lower extraction phase was separated after standing for stratification, 500 mL of DMSO was added for extraction, the extraction was repeated 5 times, the DMSO extraction phases were combined, the DMSO solvent was recovered under reduced pressure, and the raffinate phase was recovered under reduced pressure to obtain 78.21 g of mixed tocopherol concentrate (tocopherol content: 54.10%, yield: 79.23%, benzopyrene residue: 0.11 ppb, zearalenone residue: not detected).

[0053] Comparative Example 2

[0054] This comparative example provides a method for removing various undesirable impurities in mixed tocopherols (silica gel column chromatography treatment method):

[0055] 8.6 g of mixed tocopherols (tocopherol content of 53.3%, benzopyrene content of 319 ppb) were weighed and dissolved in 10 mL of n-hexane, transferred to a chromatography column equipped with 100 g of silica gel, and eluted with n-hexane-n-hexane: ethyl acetate = 4:1 (v / v)-ethyl acetate in sequence, and the component fractions containing mixed tocopherols were recovered under reduced pressure to obtain 5.89 g of mixed tocopherol concentrate (tocopherol content of 73.66%, yield of 94.64%, benzopyrene residue of 16.8 ppb).

[0056] The present invention utilizes a continuous countercurrent extraction process, and the removal of benzopyrene and zearalenone in mixed tocopherols can reach the residual amount that can be achieved after intermittent extraction, but the recovery rate of mixed tocopherols can be greatly improved, and the mixed tocopherol yield can reach 97-98%. This is because the extraction phase is repeatedly back-extracted by the raffinate phase with a low mixed tocopherol concentration during the countercurrent extraction process, thereby recovering the mixed tocopherols in the extraction phase to the maximum extent.

[0057] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction, characterized in that: The method comprises: Step 1: Configuration of light phase and heavy phase Mixing and dissolving mixed tocopherols with a light phase solution to form an extraction light phase; using a blank extract as an extraction heavy phase; Step 2: Continuous countercurrent extraction The light phase and heavy phase are introduced into the annular mixing zone formed between the drum and the shell through the light phase inlet and the heavy phase inlet respectively. With the help of the rotation of the drum, the two phases are quickly mixed and dispersed through the turbine disc and the impeller. The two-phase solution is fully transferred, completing the mixing and mass transfer process to obtain a mixed solution. The mixed liquid enters the drum under the action of the turbine disc. In the compartment area formed by the Fu plate, the mixed liquid quickly rotates synchronously with the drum. Under the action of centrifugal force, the heavy phase liquid with a large specific gravity gradually moves away from the center of the drum and approaches the drum wall during the upward flow; the light phase liquid with a small specific gravity gradually moves away from the drum wall and approaches the center. The clarified two-phase liquid finally passes through the heavy phase weir plate and the light phase weir plate to enter the heavy phase collection chamber and the light phase collection chamber respectively, and flows out of the system from the light phase outlet and the heavy phase outlet, completing the two-phase separation process, and obtaining tocopherol with undesirable impurities extracted.

2. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 1, characterized in that: In the step 1, the light phase solution is n-hexane and / or cyclohexane.

3. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 1, characterized in that: In the step 1, the ratio of the mixed tocopherol raw material to the light phase solution is 1:3-5.

4. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 3, characterized in that: The ratio of the mixed tocopherol raw material to the light phase solution is 1:

3.

5. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 1, characterized in that: In the step 1, the blank extract is one or more of sulfolane, 2,4-dimethylsulfolane, and dimethyl sulfoxide (DMSO).

6. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 4, characterized in that: The blank extract is sulfolane and / or dimethyl sulfoxide (DMSO).

7. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 5, characterized in that: The blank extract is dimethyl sulfoxide (DMSO).

8. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 1, characterized in that: In the step 1, the ratio of the mixed tocopherol raw material to the blank extract is 1:3-5.

9. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 8, characterized in that: The ratio of the mixed tocopherol raw material to the blank extract is 1:

4.

10. The method for removing multiple undesirable impurities from mixed tocopherols by continuous countercurrent extraction according to claim 1, characterized in that: In the step 2, the number of continuous countercurrent extraction stages is 5-10.

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