A method for separating microbial solution for preparing acrylamide based on microbial method

Abstract

The application discloses a bacteria liquid separation method for preparing acrylamide based on a microbial method, and relates to the technical field of acrylamide synthesis. The bacteria liquid separation method comprises the following steps: depositing a hydrophilic modifier on the surface of an ultrafiltration membrane to obtain a modified ultrafiltration membrane; adding an adsorbent to acrylamide hydrate liquid, stirring, forming agglomerates in the acrylamide hydrate liquid, removing the agglomerates through filtration to obtain pretreated liquid; filtering the pretreated liquid through the modified ultrafiltration membrane, recovering the filtered bacteria, and then sequentially performing continuous ion exchange and concentration to obtain acrylamide liquid finished product. The method disclosed by the application is helpful to reducing membrane pollution of the ultrafiltration membrane and improving the separation effect of the ultrafiltration membrane on the bacteria liquid by pre-hydrophilic modification treatment of the ultrafiltration membrane and pre-adsorption treatment of the acrylamide hydrate liquid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of acrylamide synthesis, and particularly to a microbial liquid separation method for preparing acrylamide based on a microbial method. BACKGROUND

[0002] Acrylamide is the most important compound in acrylamide and is the simplest one. Acrylamide has a wide range of uses and is usually used as a raw material for organic synthesis or a raw material for polymer materials. There are many methods for preparing acrylamide, and the microbial method for preparing acrylamide has the advantages of directional conversion and less by-products.

[0003] In the related art, the microbial method for preparing acrylamide is as follows: a microbial catalyst containing biological enzymes is prepared by microbial fermentation, and after being cleaned by microfiltration, acrylonitrile and water are catalyzed to perform hydration reaction, and acrylamide hydration liquid is prepared by hydration. After the acrylamide hydration liquid is filtered by an ultrafiltration membrane and ion exchanged, 30% acrylamide liquid product is obtained, and after further concentration after ion exchange, acrylamide liquid products with concentrations of 40%, 50%, etc. are obtained.

[0004] However, due to the presence of organic macromolecules and organic small molecules in the acrylamide hydration liquid, the organic macromolecules and the organic small molecules have physical and chemical interactions or mechanical actions with the ultrafiltration membrane, which easily causes membrane pollution and affects the liquid separation effect of the ultrafiltration membrane. SUMMARY

[0005] In order to improve the liquid separation effect of the microbial method for preparing acrylamide, the present application provides a microbial liquid separation method for preparing acrylamide based on a microbial method.

[0006] The microbial liquid separation method for preparing acrylamide based on a microbial method provided by the present application adopts the following technical scheme:

[0007] A microbial liquid separation method for preparing acrylamide based on a microbial method comprises the following steps:

[0008] Membrane modification: depositing a hydrophilic modifier on the surface of the ultrafiltration membrane to obtain a modified ultrafiltration membrane;

[0009] Pre-adsorption: adding an adsorbent to the acrylamide hydration liquid, stirring, forming agglomerates in the acrylamide hydration liquid, filtering out the agglomerates, and obtaining a pretreated liquid;

[0010] Filtration: filtering the treated liquid through the modified ultrafiltration membrane, recovering the filtered strain, and then sequentially performing continuous ion exchange and concentration to obtain acrylamide liquid product.

[0011] By adopting the technical scheme, the hydrophilic modifier can combine with water molecules to form a water layer, thereby hindering the adhesion of organic macromolecules and organic small molecules on the membrane surface, and reducing the surface tension between the organic macromolecules and the organic small molecules and liquid, thereby reducing the phenomenon of the organic macromolecules and the organic small molecules being adsorbed on the membrane surface by the liquid surface tension. Moreover, before the filtration is performed again, the adsorbent is used for pre-adsorption, so that the organic macromolecules and the organic small molecules with a large particle size in the acrylamide hydrate liquid can be removed, the amount of the organic macromolecules and the organic small molecules contacting the modified ultrafiltration membrane in the filtration step is reduced, and the membrane pollution of the ultrafiltration membrane is reduced, thereby improving the separation effect of the ultrafiltration membrane on the bacterial liquid.

[0012] In one specific embodiment, the adsorbent includes magnetic biochar with a particle size of 100-5000 nm.

[0013] By adopting the technical scheme, the magnetic biochar has excellent adsorption capacity and magnetism, so that after the magnetic biochar is used to adsorb the organic macromolecules and the organic small molecules in the acrylamide hydrate liquid, the magnetic biochar and the organic macromolecules and the organic small molecules that have not formed aggregates can be quickly removed by magnetic adsorption, the residual magnetic biochar is reduced, the bacterial liquid obtained in the filtration step is conveniently recycled and reused, and the magnetic biochar with a particle size in the above range can be used to well adsorb the organic macromolecules and the organic small molecules and is large in size and convenient to remove, thereby further reducing the residual magnetic biochar.

[0014] In one specific embodiment, the preparation method of the magnetic biochar with a particle size of 100-5000 nm includes the following steps:

[0015] 8-12 parts by weight of ordered mesoporous carbon, 3-5 parts by weight of phytic acid, 3-5 parts by weight of water, 2.4-2.8 parts by weight of FeSO4·7H2O, and 7-7.5 parts by weight of FeCl3·6H2O are weighed;

[0016] The water is divided into two parts, the phytic acid and the ordered mesoporous carbon are added to the first part of water, and stirring is uniformly performed to obtain a mixed solution;

[0017] FeSO4·7H2O and FeCl3·6H2O are dissolved in the second part of water to obtain an iron ion solution, the mixed solution is added dropwise into the iron ion solution, and soaking is performed for 12-24 h, and then filtration, washing, and drying are performed to obtain beads;

[0018] The beads are pyrolyzed at 590-620℃ for 1.6-2.2 h to obtain a crude magnetic biochar, and sieving is performed to obtain the magnetic biochar with a particle size of 100-5000 nm.

[0019] By adopting the technical scheme, after cross-linking pyrolysis, functional structures or substances such as O-Fe bonds, Fe3O4, FeO and the like are formed on the surface of the magnetic biochar, and active sites such as -COOH and -C=O are retained, which can all be combined with organic macromolecules and organic small molecules to achieve the effect of adsorbing organic macromolecules and organic small molecules. Moreover, the magnetic biochar can remove negatively charged substances through electrostatic action and the like, and therefore, the magnetic biochar prepared by the preparation method has excellent adsorption performance, which is helpful to pre-removing organic macromolecules, organic small molecules and negatively charged substances in the acrylamide hydrate liquid, and reducing membrane pollution.

[0020] In a specific implementable embodiment, in the preparation method of the magnetic biochar with a particle size of 100-5000 nm, the beads are placed in a muffle furnace, the temperature in the muffle furnace is raised at a temperature raising speed of 3-6 ℃ / min to 590-620 ℃, and pyrolysis is performed for 1.6-2.2 h to obtain a crude magnetic biochar product.

[0021] By adopting the technical scheme, the present application finds through experiments that the temperature raising speed is helpful to improving the adsorption effect of the magnetic biochar, and the prepared magnetic biochar still has a high adsorption effect after multiple pyrolysis, which is helpful to recycling and reusing the magnetic biochar.

[0022] In a specific implementable embodiment, the membrane modification step is as follows:

[0023] 100-130 parts by weight of a hydrophilic modifier and 80-110 parts by weight of a tris(hydroxymethyl)aminomethane buffer solution with a concentration of 9-12 mmol / L are weighed, the hydrophilic modifier and the tris(hydroxymethyl)aminomethane buffer solution are mixed to obtain a standby solution;

[0024] The standby solution is poured on one side surface of the ultrafiltration membrane, a barrier is used to prevent the standby solution from flowing down from the ultrafiltration membrane, the ultrafiltration membrane is fixed on a shaker, and after reaction in air at a rotation speed of 50-70 rpm for 25-35 minutes, the membrane surface is rinsed to obtain a modified ultrafiltration membrane.

[0025] By adopting the technical scheme, the tris(hydroxymethyl)aminomethane buffer solution is a commonly used weak alkaline solvent, and the hydrophilic modifier can be uniformly dispersed in the tris(hydroxymethyl)aminomethane buffer solution. On the shaker at the above rotation speed, the hydrophilic modifier is deposited on the surface of the ultrafiltration membrane to form a hydrophilic modifier layer, which improves the hydrophilicity of the surface of the ultrafiltration membrane and is helpful to preventing membrane pollution. Moreover, the present application finds through experiments that the use of the tris(hydroxymethyl)aminomethane buffer solution with the above concentration is helpful to further improving the anti-pollution performance of the ultrafiltration membrane.

[0026] In a specific implementable embodiment, the hydrophilic modifier includes dopamine hydrochloride.

[0027] By adopting the technical scheme, dopamine hydrochloride can be self-oxidized into dopamine-quinone in tris(hydroxymethyl)aminomethane buffer solution, and polydopamine can be formed through further oxidation and rearrangement, the polydopamine is deposited on the surface of the ultrafiltration membrane, the hydrophilicity of the ultrafiltration membrane can be improved, the biocompatibility of the ultrafiltration membrane can be improved, the anti-organic pollution performance of the ultrafiltration membrane can be improved, and the membrane hole blockage can be reduced, so that the membrane pollution of the ultrafiltration membrane is prevented.

[0028] In a specific implementable scheme, the hydrophilic modifier further comprises tetradecyl sulfobetaine, and the weight ratio of the tetradecyl sulfobetaine to dopamine hydrochloride is 1:(0.85-1.15).

[0029] By adopting the technical scheme, the tetradecyl sulfobetaine is a quaternary ammonium salt amphoteric surfactant, has the same number of cation and silver ion groups, and is deposited on the surface of the ultrafiltration membrane together with the polydopamine according to the above-mentioned ratio, so that the ability of the ultrafiltration membrane to combine water molecules through electrostatic force can be improved, the stability of the polydopamine can be improved, the anti-pollution performance of the ultrafiltration membrane can be further improved, and the anti-pollution durability and stability of the ultrafiltration membrane can be improved.

[0030] In a specific implementable scheme, in the membrane modification step, the ultrafiltration membrane is soaked in an ethanol aqueous solution with a volume concentration of ≥75% for 20-50 min, and then the standby solution is poured on one side surface of the ultrafiltration membrane after washing with water.

[0031] By adopting the above-mentioned pretreatment step, the anti-pollution performance of the ultrafiltration membrane can be improved. This may be because the ethanol aqueous solution with the above-mentioned concentration can remove impurities on the surface of the ultrafiltration membrane, and help to improve the deposition effect, so that the anti-pollution performance of the ultrafiltration membrane is improved.

[0032] In summary, the present application has at least one of the following beneficial technical effects:

[0033] 1. The method of the present application can help to reduce the membrane pollution of the ultrafiltration membrane, and improve the separation effect of the ultrafiltration membrane on the bacterial solution by pretreating the ultrafiltration membrane with a hydrophilic modification treatment and pretreating the acrylamide hydrate solution with an adsorption treatment.

[0034] 2. The present application can help to remove organic macromolecules, organic small molecules and negatively charged substances in the acrylamide hydrate solution in advance by optimizing the magnetic biochar, and reduce the membrane pollution.

[0035] 3. The present application can help to further improve the anti-pollution performance of the ultrafiltration membrane by optimizing the hydrophilic modifier and optimizing the membrane modification step. DETAILED DESCRIPTION

[0036] The application will be further described in detail in connection with examples and comparative examples.

[0037] Example

[0038] Example 1

[0039] The example provides a magnetic biochar, which uses the following components: 10 kg ordered mesoporous carbon, 4 kg phytic acid, 4 kg water, 2.6 kg FeSO4·7H2O, and 7.25 kg FeCl3·6H2O.

[0040] The example provides a method for preparing the magnetic biochar, which uses the following steps:

[0041] Divide the water into two equal parts, mix the phytic acid with the first part of water, stir until uniform, then add the ordered mesoporous carbon, continue stirring until uniform, and obtain a mixed solution.

[0042] Mix FeSO4·7H2O and FeCl3·6H2O with the second part of water, stir until completely dissolved, and obtain an iron ion solution. Then, drop the mixed solution into the iron ion solution, soak for 18 h, filter, collect the solid, rinse the solid with deionized water, and then dry the solid at 65℃ under ventilation, and obtain the bead.

[0043] Put the bead into a muffle furnace, raise the temperature in the muffle furnace to 605℃ at a speed of 4.5℃ / min, and then pyrolyze for 2 h, obtain a crude product of magnetic biochar, sieve, and obtain magnetic biochar with a particle size of 100-5000 nm.

[0044] The example provides a method for separating a bacteria solution for preparing acrylamide based on a microbial method, which includes the following steps:

[0045] Form a closed area on the surface of one side of the ultrafiltration membrane with a fence, add 122.1 g of dopamine hydrochloride to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5 mmol / L, stir until uniform, and obtain a standby solution. Pour the standby solution into the closed area on the ultrafiltration membrane, and prevent the standby solution from flowing down by the fence. Then, fix the ultrafiltration membrane on a shaker, adjust the rotation speed of the shaker to 60 rpm, and react for 30 min under air conditions. Stop the reaction, take out the ultrafiltration membrane, remove the fence, and rinse the membrane surface with deionized water, and obtain a modified ultrafiltration membrane.

[0046] Add the magnetic biochar described above to the acrylamide aqueous solution, shake for 2 h at 25℃ and a rotation speed of 200 rpm on a constant temperature shaker, and form agglomerates in the acrylamide aqueous solution. Remove the agglomerates by filtration, and obtain a pretreated solution.

[0047] The treatment liquid is filtered through the modified ultrafiltration membrane, the filtered bacterial strain is recovered, and then sequentially subjected to continuous ion exchange and concentration to obtain an acrylamide liquid product.

[0048] Example 2

[0049] The present embodiment provides a bacterial liquid separation method for preparing acrylamide based on a microbial method. The only difference between the present embodiment and Example 1 is that the magnetic biochar uses the following components: 8 kg of ordered mesoporous carbon, 3 kg of phytic acid, 3 kg of water, 2.4 kg of FeSO4·7H2O, and 7 kg of FeCl3·6H2O.

[0050] Example 3

[0051] The present embodiment provides a bacterial liquid separation method for preparing acrylamide based on a microbial method. The only difference between the present embodiment and Example 1 is that the magnetic biochar uses the following components: 12 kg of ordered mesoporous carbon, 5 kg of phytic acid, 5 kg of water, 2.8 kg of FeSO4·7H2O, and 7.5 kg of FeCl3·6H2O.

[0052] Example 4

[0053] The present embodiment provides a bacterial liquid separation method for preparing acrylamide based on a microbial method. The only difference between the present embodiment and Example 1 is that the magnetic biochar uses the following components: 7 kg of ordered mesoporous carbon, 2.5 kg of phytic acid, 2.5 kg of water, 2.2 kg of FeSO4·7H2O, and 6.8 kg of FeCl3·6H2O.

[0054] Example 5

[0055] The present embodiment provides a bacterial liquid separation method for preparing acrylamide based on a microbial method. The only difference between the present embodiment and Example 1 is that the magnetic biochar uses the following components: 13 kg of ordered mesoporous carbon, 5.5 kg of phytic acid, 5.5 kg of water, 3.0 kg of FeSO4·7H2O, and 7.7 kg of FeCl3·6H2O.

[0056] Example 6

[0057] The present embodiment provides a bacterial liquid separation method for preparing acrylamide based on a microbial method. The only difference between the present embodiment and Example 1 is that the preparation method of the magnetic biochar is as follows:

[0058] FeSO4·7H2O and FeCl3·6H2O are mixed with the second portion of water and stirred until completely dissolved to obtain an iron ion solution. Then, the mixed solution is added dropwise to the iron ion solution, soaked for 12 h, filtered, the solid is washed with deionized water, and then the solid is dried at 65°C under ventilation to obtain the bead body.

[0059] Put the beads into the muffle furnace, and raise the temperature in the muffle furnace to 590℃ at a speed of 4.5℃ / min, then keep the temperature for pyrolysis for 2.2h, to obtain the crude product of magnetic biochar, and sieve to obtain magnetic biochar with a particle size of 100-5000nm.

[0060] Example 7

[0061] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method, and the difference between the present example and Example 1 is only that the preparation method of the magnetic biochar is as follows:

[0062] Mix FeSO4·7H2O and FeCl3·6H2O with the second portion of water, stir until completely dissolved to obtain an iron ion solution, then drop the mixed solution into the iron ion solution, soak for 24h, filter, collect the solid, rinse the solid with deionized water, then dry the solid at 65℃ under ventilation, to obtain the beads.

[0063] Put the beads into the muffle furnace, and raise the temperature in the muffle furnace to 620℃ at a speed of 4.5℃ / min, then keep the temperature for pyrolysis for 1.6h, to obtain the crude product of magnetic biochar, and sieve to obtain magnetic biochar with a particle size of 100-5000nm.

[0064] Example 8

[0065] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method, and the difference between the present example and Example 1 is only that the preparation method of the magnetic biochar is as follows:

[0066] Put the beads into the muffle furnace, and raise the temperature in the muffle furnace to 605℃ at a speed of 3℃ / min, then keep the temperature for pyrolysis for 2h, to obtain the crude product of magnetic biochar.

[0067] Example 9

[0068] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method, and the difference between the present example and Example 1 is only that the preparation method of the magnetic biochar is as follows:

[0069] Put the beads into the muffle furnace, and raise the temperature in the muffle furnace to 605℃ at a speed of 6℃ / min, then keep the temperature for pyrolysis for 2h, to obtain the crude product of magnetic biochar.

[0070] Example 10

[0071] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method, and the difference between the present example and Example 1 is only that the preparation method of the magnetic biochar is as follows:

[0072] Put the beads into the muffle furnace, and raise the temperature in the muffle furnace to 605℃ at a rate of 2℃ / min, and then keep the temperature for 2h to obtain the crude product of magnetic biochar.

[0073] Example 11

[0074] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method. The difference between the present example and Example 1 is only that in the preparation method of magnetic biochar:

[0075] Put the beads into the muffle furnace, and raise the temperature in the muffle furnace to 605℃ at a rate of 7℃ / min, and then keep the temperature for 2h to obtain the crude product of magnetic biochar.

[0076] Example 12

[0077] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method. The difference between the present example and Example 1 is only that in the preparation method of magnetic biochar:

[0078] Example 13

[0079] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method. The difference between the present example and Example 1 is only that in the preparation method of magnetic biochar:

[0080] Example 14

[0081] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method. The difference between the present example and Example 1 is only that the magnetic biochar is replaced by an equal amount of ordered mesoporous carbon.

[0082] Example 15

[0083] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method. The difference between the present example and Example 1 is only that 100g of dopamine hydrochloride is added to 80g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5mmol / L, and stirred until uniform to obtain a standby solution.

[0084] Example 16

[0085] The present example provides a method for separating bacterial liquid for preparing acrylamide based on microbial method. The difference between the present example and Example 1 is only that 130g of dopamine hydrochloride is added to 110g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5mmol / L, and stirred until uniform to obtain a standby solution.

[0086] Example 17

[0087] The present example provides a method for separating bacteria solution for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 9 mmol / L, and stirred until uniform to obtain a standby solution.

[0088] Example 18

[0089] The present example provides a method for separating bacteria solution for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 12 mmol / L, and stirred until uniform to obtain a standby solution.

[0090] Example 19

[0091] The present example provides a method for separating bacteria solution for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that the rotation speed of the shaker is adjusted to 50 rpm, and after reacting for 35 min under air condition, the reaction is stopped, the ultrafiltration membrane is taken out, the surrounding barrier is removed, and the membrane surface is washed with deionized water to obtain a modified ultrafiltration membrane.

[0092] Example 20

[0093] The present example provides a method for separating bacteria solution for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that the rotation speed of the shaker is adjusted to 70 rpm, and after reacting for 25 min under air condition, the reaction is stopped, the ultrafiltration membrane is taken out, the surrounding barrier is removed, and the membrane surface is washed with deionized water to obtain a modified ultrafiltration membrane.

[0094] Example 21

[0095] The present example provides a method for separating bacteria solution for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 9 mmol / L, and stirred until uniform to obtain a standby solution.

[0096] Example 22

[0097] The present example provides a method for separating bacteria solution for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 9 mmol / L, and stirred until uniform to obtain a standby solution.

[0098] Example 23

[0099] The present example provides a method for separating microbial liquid for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that a mixture of 56.79 g of tetradecyl sulfobetaine and 65.31 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5 mmol / L, stirred until uniform, to obtain a standby solution.

[0100] Example 24

[0101] The present example provides a method for separating microbial liquid for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that the ultrafiltration membrane is soaked in an aqueous ethanol solution with a volume concentration of 75% for 35 min, then rinsed with deionized water, and a closed area is formed on the surface of one side of the ultrafiltration membrane using a barrier, 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5 mmol / L, stirred until uniform, to obtain a standby solution, and the standby solution is poured into the closed area on the ultrafiltration membrane.

[0102] Example 25

[0103] The present example provides a method for separating microbial liquid for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that the ultrafiltration membrane is soaked in an aqueous ethanol solution with a volume concentration of 75% for 50 min, then rinsed with deionized water, and a closed area is formed on the surface of one side of the ultrafiltration membrane using a barrier, 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5 mmol / L, stirred until uniform, to obtain a standby solution, and the standby solution is poured into the closed area on the ultrafiltration membrane.

[0104] Example 26

[0105] The present example provides a method for separating microbial liquid for preparing acrylamide based on microbial method. The only difference between the present example and Example 1 is that the ultrafiltration membrane is soaked in an aqueous ethanol solution with a volume concentration of 95% for 20 min, then rinsed with deionized water, and a closed area is formed on the surface of one side of the ultrafiltration membrane using a barrier, 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5 mmol / L, stirred until uniform, to obtain a standby solution, and the standby solution is poured into the closed area on the ultrafiltration membrane.

[0106] Comparative Example

[0107] Comparative Example 1

[0108] The comparative example provides a magnetic biochar, which adopts the following components: 10 kg ordered mesoporous carbon, 4 kg phytic acid, 4 kg water, 2.6 kg FeSO4·7H2O, and 7.25 kg FeCl3·6H2O.

[0109] The preparation method of the magnetic biochar adopts the following steps:

[0110] The water is evenly divided into two parts, the phytic acid is mixed with the first part of water, stirred uniformly, and then the ordered mesoporous carbon is added and continuously stirred until uniform, to obtain a mixed solution.

[0111] FeSO4·7H2O and FeCl3·6H2O are mixed with the second part of water and stirred until completely dissolved to obtain an iron ion solution. Then, the mixed solution is added dropwise into the iron ion solution, soaked for 18 h, filtered, the solid is washed with deionized water, and then the solid is dried at 65℃ under ventilation to obtain the bead body.

[0112] The bead body is placed in a muffle furnace, the temperature in the muffle furnace is raised to 605℃ at a speed of 4.5℃ / min, and then pyrolysis is carried out for 2 h to obtain a crude magnetic biochar, which is sieved to obtain a magnetic biochar with a particle size of 100-5000 nm.

[0113] The comparative example provides a bacteria liquid separation method for preparing acrylamide based on a microbial method, which includes the following steps:

[0114] The magnetic biochar is added to the acrylamide aqueous solution, and after oscillation for 2 h at 25℃ and a constant temperature shaker with a rotation speed of 200 rpm, agglomerates are formed in the acrylamide aqueous solution. The agglomerates are removed by filtration to obtain a pretreated liquid.

[0115] The treatment liquid is filtered through an ultrafiltration membrane, the filtered bacteria are recovered, and then sequentially subjected to continuous ion exchange and concentration to obtain an acrylamide liquid product.

[0116] Comparative example 2

[0117] The comparative example provides a bacteria liquid separation method for preparing acrylamide based on a microbial method, which adopts the following steps:

[0118] A closed area is formed on the surface of one side of the ultrafiltration membrane by a barrier, 122.1 g of dopamine hydrochloride is added to 95 g of tris(hydroxymethyl)aminomethane buffer solution with a concentration of 10.5 mmol / L, stirred until uniform to obtain a standby solution, the standby solution is poured into the closed area on the ultrafiltration membrane, and the barrier prevents the standby solution from flowing down. Then the ultrafiltration membrane is fixed on a shaker, the rotation speed of the shaker is adjusted to 60 rpm, and the reaction is carried out under air conditions for 30 min, then the reaction is stopped, the ultrafiltration membrane is taken out, the barrier is removed, and the membrane surface is washed with deionized water to obtain a modified ultrafiltration membrane.

[0119] The acrylamide aqueous solution is filtered through the modified ultrafiltration membrane, the filtered strain is recovered, and then sequentially subjected to continuous ion exchange and concentration to obtain the acrylamide liquid product.

[0120] Comparative Example 3

[0121] The present comparative example provides a method for separating a bacterial solution for preparing acrylamide based on a microbial method, which comprises the following steps:

[0122] The acrylamide aqueous solution is filtered through the modified ultrafiltration membrane, the filtered strain is recovered, and then sequentially subjected to continuous ion exchange and concentration to obtain the acrylamide liquid product.

[0123] Performance detection test

[0124] For Examples 1-25 and Comparative Examples 1-3, the following detections are performed:

[0125] Hydrophilicity detection: The surface water contact angle of the modified ultrafiltration membrane and the ultrafiltration membrane for filtering in each example and comparative example is detected by the sessile drop method of an SDC-100S contact angle measuring instrument. The smaller the contact angle of the membrane, the stronger the hydrophilicity, and the stronger the anti-fouling ability of the corresponding membrane.

[0126] Membrane fouling test:

[0127] The modified ultrafiltration membrane or the ultrafiltration membrane after filtering in each example and comparative example is pre-pressurized with 200 mL of ultrapure water at a constant pressure ΔP = 0.4 bar, and then the pure water flux of the membrane is measured at 0.2 bar until the flux reaches a stable value (constant flux value (J0), which remains stable within at least 10 minutes of continuous measurement). The constant pressure required for the experiment is provided by high-pressure nitrogen gas. According to the following formula, the water permeability (PWP, L·m -2 ·h -1 ·bar -1 ):

[0128] Wherein V represents the permeate volume (L), A represents the effective area of the membrane (m 2 ), Δt is the permeate collection interval (h), and ΔP is the pressure used in the experiment (bar). The results are shown in Table 1.

[0129] Table 1

[0130]

[0131] It can be seen from the combination of the embodiments 1 and comparative examples 1-3 and Table 1 that the water contact angles of the comparative examples 1 and 3 are obviously larger than that of the embodiment 1, and the water permeation rates of the comparative examples 1-3 are obviously smaller than that of the embodiment 1, which indicates that compared with the ultrafiltration membrane, the modified ultrafiltration membrane has better hydrophilicity, and under the method of the embodiment 1, it is helpful to reduce the membrane pollution phenomenon of the modified ultrafiltration membrane.

[0132] It can be seen from the combination of the embodiments 1-26 and Table 1 that the water contact angles of the modified ultrafiltration membranes of the embodiments 1-14 are unchanged, and the water permeation rates are all larger than that of the comparative example 2, which indicates that under the method conditions of the embodiments 1-14, it is helpful to reduce the membrane pollution phenomenon of the modified ultrafiltration membrane. The water contact angles of the modified ultrafiltration membranes of the embodiments 1 and 15-26 are all changed slightly, and the water permeation rates are all larger, which indicates that under the method conditions of the embodiments 1 and 15-16, it is helpful to reduce the membrane pollution phenomenon of the modified ultrafiltration membrane.

[0133] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution according to the needs after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for separating a microbial broth for preparing acrylamide based on a microbial method, characterized by, It comprises the following steps: Membrane modification: depositing a hydrophilic modifier on the surface of the ultrafiltration membrane to obtain a modified ultrafiltration membrane; Pre-adsorption: adding an adsorbent to the acrylamide hydrate solution, stirring, forming agglomerates in the acrylamide hydrate solution, filtering out the agglomerates to obtain a pretreated solution; Filtration: filtering the treated solution through the modified ultrafiltration membrane, recovering the filtered strain, and then sequentially passing through continuous ion exchange and concentration to obtain acrylamide liquid finished product; The adsorbent comprises magnetic biochar with a particle size of 100-5000 nm. The preparation method of the magnetic biochar with a particle size of 100-5000 nm comprises the following steps: Weigh 8-12 parts by weight of ordered mesoporous carbon, 3-5 parts by weight of phytic acid, 3-5 parts by weight of water, 2.4-2.8 parts by weight of FeSO4·7H2O, and 7-7.5 parts by weight of FeCl3·6H2O; Divide the water into two parts, add phytic acid and ordered mesoporous carbon to the first part of water, stir evenly to obtain a mixed solution; Dissolve FeSO4·7H2O and FeCl3·6H2O in the second part of water to obtain an iron ion solution, add the mixed solution dropwise to the iron ion solution, soak for 12-24 hours, filter, wash and dry to obtain beads; Pyrolyze the beads at 590-620℃ for 1.6-2.2h to obtain crude magnetic biochar, sieve to obtain magnetic biochar with a particle size of 100-5000 nm.

2. The method for separating the bacterial solution for preparing acrylamide based on the microbial method according to claim 1, characterized in that, In the preparation method of the magnetic biochar with a particle size of 100-5000 nm, the beads are placed in a muffle furnace, the temperature in the muffle furnace is raised to 590-620℃ at a heating rate of 3-6℃ / min, and pyrolysis is carried out for 1.6-2.2h to obtain crude magnetic biochar.

3. The method for separating the bacterial solution for preparing acrylamide based on the microbial method according to claim 1, characterized in that, The membrane modification step is as follows: Weigh 100-130 parts by weight of a hydrophilic modifier and 80-110 parts by weight of a tris(hydroxymethyl)aminomethane buffer with a concentration of 9-12 mmol / L, mix the hydrophilic modifier and the tris(hydroxymethyl)aminomethane buffer to obtain a standby solution; Pour the standby solution onto one side of the surface of the ultrafiltration membrane, use a barrier to prevent the standby solution from flowing down from the ultrafiltration membrane, fix the ultrafiltration membrane on a shaker, and react in air at a speed of 50-70 rpm for 25-35 minutes, then rinse the membrane surface to obtain a modified ultrafiltration membrane.

4. The method for separating the bacterial solution for preparing acrylamide based on the microbial method according to claim 3, characterized in that, The hydrophilic modifier comprises dopamine hydrochloride.

5. The method for separating the bacterial solution for preparing acrylamide based on the microbial method according to claim 4, characterized in that, The hydrophilic modifier further comprises tetradecyl sulfobetaine, and the weight ratio of tetradecyl sulfobetaine to dopamine hydrochloride is 1:(0.85-1.15).

6. The method for separating the bacterial solution for preparing acrylamide based on the microbial method according to claim 1, characterized in that, In the membrane modification step, the ultrafiltration membrane is previously soaked in an ethanol aqueous solution with a volume concentration of ≥75% for 20-50 minutes, and then washed with water before pouring the standby solution onto one side of the surface of the ultrafiltration membrane.

Images