CN105582864B - A kind of vegetable protein aeroge and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of vegetable protein aeroge and preparation method thereof, belong to aeroge field.The present invention solves the problems, such as to rely on vegetable protein that aeroge is made by vacuum freeze drying merely.Specific method is：Plant protein powder is handled through alkali liquor hydrothermal albumen glue is made；Addition crosslinking agent stands to form gel；Gel is replaced with displacement solvent, freezed, vacuum drying obtains vegetable protein aeroge.The aeroge apparent density is 0.15 ~ 0.2g/cm³, specific surface area is 110 ~ 130m²/ g, rich in mesoporous, adsorbent can be used as.Raw material is easy to get in preparation process, cost is cheap and green；Preparation technology is simple, and the cycle is short, safe.

Description

A kind of vegetable protein airgel and preparation method thereof

technical field

The invention belongs to the field of airgel preparation; more specifically, it relates to a plant protein airgel and a preparation method thereof.

Background technique

Airgel is a porous material with gas as a dispersion medium and a pore size in the range of nanometers. It is the lightest solid material currently known. Airgel has the characteristics of large specific surface area, high porosity, low density and thermal conductivity; it has broad application prospects in the fields of catalyst carriers, biomedicine, adsorption materials, thermal insulation materials, and energy storage materials. In order to ensure the performance of inorganic aerogels, the precursors used are highly toxic or expensive, while traditional organic aerogels are highly dependent on fossil resources such as petroleum and coal. In order to protect resources and the environment and reduce the cost of airgel preparation, the use of renewable biomass to prepare aerogels has attracted widespread attention. For example, the invention patent with the publication number 102602944A discloses a method of preparing inorganic aerogels from rice husks. Method; the invention patent with publication number 102417606A discloses a preparation method of chitin airgel; the invention patent with publication number 103205015A discloses a transparent and flexible cellulose airgel and its preparation method.

Existing aerogels mainly form wet gels through precursors in solvents, and then dry and preserve the pore structure in the gels to prepare aerogels. The wet gel formed by the precursor has poor performance and weak skeleton strength, and powdery airgel is often obtained after drying. The pore structure of airgel is best preserved after supercritical drying, but it has disadvantages such as complicated operation, high risk, and high cost. The preparation of airgel by normal pressure drying requires high treatment of wet gel, narrow applicability, and poor structure of the prepared airgel. Vacuum freeze-drying can preserve the pore structure in the wet gel better than normal pressure drying, and is safer and less costly than supercritical drying, but it often results in micron-sized pores after drying due to the crystallization of the liquid in the wet gel during freezing. porous material.

Among biomass materials, proteins have been widely used in the research of porous materials because of their good biocompatibility, many active functional groups, and easy gel formation. The invention patent with the publication number 102512710A provides a method for preparing a porous silk fibroin three-dimensional material, but the porous material needs to be concentrated before forming a gel. Class material enriched in mesoporous standards. The invention patent with the publication number of 104843668 discloses a method of preparing nitrogen-doped porous carbon material with biological protein. Although the porous material meets the standard of airgel, it needs to be carbonized to increase the micropore and mesopore of the material. During the treatment process, it is classified as carbon aerogel, and it is in powder form, which is not conducive to separation and recovery. Publication No. 104107681A invention patent provides a method for preparing a three-dimensional graphene-protein composite airgel, which relies on the composite of protein and graphene, and the mesopores in the airgel are mainly contributed by graphene .

In summary, the use of renewable biomass and non-supercritical drying to prepare aerogels is the future development trend of this material, and the preparation of aerogels from natural proteins has broad prospects. The existing protein-based porous materials have a long preparation cycle and complicated processes, and it is difficult to obtain airgel with nanoscale pores through vacuum freeze-drying.

Contents of the invention

In order to solve the above problems, the present invention provides a plant protein airgel and a preparation method thereof. The airgel does not need to be compounded with other porous materials during the preparation process; the precursor can quickly form a hydrogel, the preparation process is simple and the cycle is short; after vacuum freeze-drying, a pore structure rich in mesoporous pores can be obtained without carbonization, which can be used as adsorption material.

In order to achieve the above object, the present invention adopts the following technical solutions:

A kind of preparation method of vegetable protein airgel, concrete steps are as follows:

1) Put vegetable protein powder, lye and water into the reaction kettle, and obtain protein glue after hydrothermal treatment;

2) Add the cross-linking agent aqueous solution to the protein glue in step 1), and form a gel after stirring and standing;

3) The gel in step 2) is subjected to replacement solvent replacement treatment, freezing, and vacuum freeze-drying to obtain vegetable protein aerogels.

The weight ratio of vegetable protein powder, lye, water, and crosslinking agent aqueous solution is: 30~50:120~400:30~100:21~38.

Further, the specific refinement steps of the preparation method are:

① Prepare the required lye and cross-linking agent aqueous solution for later use;

②Put vegetable protein powder, water and lye into the reaction kettle in proportion, control the temperature at 65~95℃, mix and stir for 30~60min to obtain protein glue;

③ Add the crosslinking agent aqueous solution into the protein glue solution according to the number of parts, stir for 15~50min, then pour it into the mold and let it stand for 2~48h to form a gel;

④ Submerge the whole gel in the replacement solvent at room temperature, replace the replacement solvent every 8 hours, and replace it 3 to 8 times in a row;

⑤ Freeze the gel after replacing the solvent with liquid nitrogen for 5-10 minutes, and then vacuum freeze-dry for 24-72 hours to obtain the plant protein aerogel.

The vegetable protein powder is one or more mixtures of defatted soybean powder, soybean protein isolate powder, peanut protein powder, wheat gluten powder, pea protein powder and corn gluten powder;

The water is distilled water or boiler condensed water;

The lye is one or more mixtures of sodium hydroxide aqueous solution, calcium hydroxide aqueous solution and ammonia water, and the pH value of the lye is 9-13;

The cross-linking agent is one or more mixtures of calcium chloride, gluconolactone, formaldehyde, acetaldehyde, glyoxal, and glutaraldehyde; the molar concentration of the cross-linking agent molecule in the cross-linking agent aqueous solution is 0.0003 ~0.012mol/mL.

The replacement solvent is one or a mixture of water, absolute ethanol, acetone, and n-hexane, and the volume ratio of the first replacement solvent to the gel is 1:1.

The standing temperature of the standing to form a gel is 10-40°C.

After the replacement solvent is used for the first time, it can be recovered by distillation and reused.

The plant protein airgel made with raw material formula of the present invention and method thereof has following characteristics:

① The precursor plant protein for preparing airgel is a green and renewable resource with abundant sources and non-toxic;

②The conditions required for the formation of hydrogel are low and the speed is fast, and the hydrogel with good structure can be formed in a short time by adjusting the process at room temperature;

③Fast freezing and drying, low energy consumption;

④ Good biocompatibility, protein raw materials are the main materials for preparing bioscaffolds.

Compared with the existing biomass airgel, the present invention has the following advantages:

1) The precursor plant protein has good solubility in water, and can be completely dissolved in water-alkali system solvent only after a short period of hydrothermal treatment;

2) The process is simple, less equipment is required, the operation safety is high, the preparation cycle is short, the energy consumption is small, and the production cost is low;

3) No need to compound with other porous materials, no supercritical drying, no carbonization, no activation can obtain an apparent density of 0.15~0.2g/cm ³ , a specific surface area of 110~130m ² /g, rich in mesoporous gas condensation glue.

detailed description

The specific preparation steps of vegetable protein airgel of the present invention are as follows:

1) Prepare lye with a pH value of 9~13 and a crosslinking agent aqueous solution with a molecular molar concentration of 0.0003~0.012mol/mL for later use;

2) Put 30~50 parts of plant protein powder, 100~400 parts of water, and 30~100 parts of lye into the reaction kettle in proportion, control the temperature at 65~95°C, and mix and stir for 30~60 minutes to obtain protein glue;

3) Add 21~38 parts of cross-linking agent aqueous solution into the protein glue, stir for 15~50min, then pour into the mold, and stand at 10~40℃ for 2~48h to form a gel;

4) Submerge the whole gel into the replacement solvent at room temperature, replace the replacement solvent every 8 hours, and replace it continuously for 3 to 8 times, and recover the used replacement solvent;

5) Freeze the gel after replacing the solvent with liquid nitrogen for 5-10 minutes, and then vacuum freeze-dry for 24-72 hours to obtain the plant protein airgel.

The present invention is further clarified in conjunction with the following specific examples, but the present invention is not limited thereto.

Example 1

Use sodium hydroxide to prepare a lye with a pH of 10, and prepare glutaraldehyde into an aqueous solution of a cross-linking agent with a molecular molar concentration of 0.0003mol/mL for subsequent use; prepare 39 parts of soybean protein powder, 201 parts of distilled water and 60 parts of lye in sequence Put it into a 0.5-ton reaction kettle, control the temperature at 65°C, and stir for 60 minutes to obtain soybean protein glue; add 21 parts of cross-linking agent aqueous solution to the protein glue, and stir for 15 minutes, then pour it into a mold, and stand at a temperature of 25°C Set aside for 2 hours to form a gel; first submerge the whole piece of gel in an equal volume of distilled water at room temperature for 8 hours, for 2 consecutive times, then replace it with an equal volume of absolute ethanol for 8 hours, and recover the used ethanol; the gel after ethanol replacement Soak in liquid nitrogen for 5 minutes, freeze and dry in vacuum for 24 hours to obtain soybean protein aerogel.

Example 2

Utilize calcium hydroxide to prepare lye with a pH of 9, mix glutaraldehyde and glyoxal at a molar ratio of 1:2, and prepare an aqueous crosslinking agent solution with a molecular molar concentration of 0.0004mol/mL for subsequent use; peanut protein powder Mix 35 parts, 190 parts of distilled water, and 50 parts of lye into a 0.5-ton reactor, control the temperature at 95°C, and stir for 30 minutes to obtain peanut protein glue; add 34 parts of cross-linking agent aqueous solution to peanut protein glue, and stir for 15 minutes, then Pour into the mold and stand at 30°C for 24 hours to form a gel; first submerge the whole gel in an equal volume of distilled water at room temperature for 8 hours, for 2 consecutive times, then replace it with an equal volume of absolute ethanol for 8 hours, for 3 consecutive times , and recover the used ethanol; soak the ethanol-substituted gel in liquid nitrogen for 10 minutes, freeze it, and vacuum freeze-dry it for 30 hours to obtain peanut protein aerogel.

Example 3

Mix sodium hydroxide and calcium hydroxide at a weight ratio of 2:1 to prepare a mixed lye with a pH of 12, and mix glutaraldehyde, glyoxal, and formaldehyde at a molar ratio of 1:2:6 to prepare a molecular mole The mixed cross-linking agent aqueous solution with a concentration of 0.008mol/mL is used for later use; mix 30 parts of wheat gluten powder, 120 parts of distilled water, and 100 parts of lye into a 0.5-ton reactor, control the temperature at 75°C, and stir for 30 minutes to obtain wheat protein glue; Add 38 parts of the cross-linking agent aqueous solution to the wheat protein glue, and stir for 25 minutes, then pour it into the mold, and let it stand at a temperature of 25°C for 24 hours to form a gel; first, submerge the whole piece of gel in an equal volume of distilled water at room temperature for 8 hours , 3 times in a row, and then replaced with an equal volume of acetone for 8 hours, and then replaced with an equal volume of absolute ethanol for 8 hours, for 2 consecutive times, and recovered the used acetone and ethanol; the gel after the replacement of acetone and ethanol was immersed in liquid nitrogen 10 minutes, after freezing, vacuum freeze-drying for 48 hours to obtain wheat protein aerogel.

Example 4

Mix sodium hydroxide and ammonia water at a weight ratio of 1:12 to prepare a lye with a pH of 13, and mix calcium chloride and 40wt% glyoxal solution at a molar ratio of 1:1 to prepare a molecular molar concentration of 0.006mol/ Mix 5 mL of cross-linking agent aqueous solution, mix soybean protein isolate and peanut protein powder in a weight ratio of 1:1, and set aside; take 50 parts of the mixture of soybean protein powder and peanut protein powder, 400 parts of boiler condensate water, and 50 parts of lye and mix them into In a 0.5-ton reactor, control the temperature at 90°C and stir for 50 minutes to obtain protein glue; add 36 parts of cross-linking agent aqueous solution to the glue, and stir for 50 minutes, then pour into the mold, and stand at 35°C for 48 hours to form a gel ;First submerge the whole gel in an equal volume of distilled water at room temperature for 8 hours, 4 times in a row, then replace it with an equal volume of acetone for 8 hours, then replace it with an equal volume of n-hexane for 8 hours, for 2 consecutive times, and then replace it with an equal volume of absolute ethanol 8h, and recover the used acetone, n-hexane and ethanol; soak the gel replaced by acetone, n-hexane and ethanol in liquid nitrogen for 5min, and then vacuum freeze-dry for 36h to obtain soybean/peanut protein airgel .

Example 5

Use sodium hydroxide to prepare lye with a pH of 11, use formaldehyde solution to prepare a crosslinking agent aqueous solution with a molecular molar concentration of 0.003mol/mL, mix soybean protein isolate powder and pea protein powder in a weight ratio of 2:1, and set aside; Take 39 parts of a mixture of soybean protein isolate powder and pea protein powder, 231 parts of distilled water, and 30 parts of lye, mix them into a 0.5-ton reaction kettle, control the temperature at 70°C, and stir for 50 minutes to obtain a protein glue; add 27 parts of a cross-linking agent aqueous solution to the glue solution, and stirred for 40min, then poured into the mold, and stood at a temperature of 40°C for 12h to form a gel; first, the whole piece of gel was submerged in an equal volume of distilled water at room temperature for 8h, for 4 consecutive times, and then replaced with an equal volume of acetone 8h, 2 times in a row, then replaced with an equal volume of n-hexane for 8h, then replaced with an equal volume of absolute ethanol for 8h, and recovered the used acetone, n-hexane and ethanol; In liquid nitrogen for 8 minutes, freeze-dried in vacuum for 72 hours after freezing, the soybean/pea protein airgel was obtained.

Example 6

Calcium hydroxide and ammonia water are mixed at a weight ratio of 1:10 to prepare a lye with a pH of 10, calcium chloride is prepared to be a cross-linking agent aqueous solution with a molecular molar concentration of 0.012mol/mL, and defatted soybean flour and corn The protein powder is mixed at a weight ratio of 1:1 and set aside; take 39 parts of a mixture of defatted soybean flour and corn gluten powder, 240 parts of boiler condensate water, and 30 parts of lye, mix them into a 0.5-ton reactor, control the temperature at 80°C, and stir for 60 minutes to obtain protein. Glue solution: add 34 parts of cross-linking agent aqueous solution to the glue solution, and stir for 30 minutes, then pour into the mold, and let it stand at 40°C for 6 hours to form a gel; first, submerge the whole piece of gel in an equal volume of distilled water at room temperature to replace 8 hours, 8 times in a row; the gel replaced by distilled water was soaked in liquid nitrogen for 10 minutes, frozen and then vacuum freeze-dried for 40 hours to obtain a plant protein aerogel.

Example 7

Calcium hydroxide is used to prepare lye with a pH of 9, gluconolactone is used to prepare a crosslinking agent aqueous solution with a molecular molar concentration of 0.01mol/mL, and acetaldehyde is used to prepare a crosslinking agent aqueous solution with a molecular molar concentration of 0.002mol/mL. Mix soybean protein isolate, wheat protein powder, and peanut protein powder at a ratio of 1:1:1, and set aside; take 39 parts of a mixture of soybean protein isolate, wheat protein powder, and peanut protein powder, 190 parts of boiler condensate, and 70 parts of lye Mix parts into a 0.5-ton reactor, control the temperature at 85°C, and stir for 40 minutes to obtain protein glue; first add 11 parts of gluconolactone crosslinking agent aqueous solution to the glue, stir for 10 minutes, and then add 16 parts of acetaldehyde crosslinking agent aqueous solution Add glue, continue to stir for 25 minutes, then pour into the mold, and stand at 10°C for 3 hours to form a gel; first submerge the whole gel in an equal volume of distilled water at room temperature for 8 hours, for 2 consecutive times, and then use an equal volume Replace with n-hexane for 8 hours, twice in a row, then replace with an equal volume of absolute ethanol for 8 hours, and recover the used n-hexane and ethanol; immerse the gel after replacing with n-hexane and ethanol in liquid nitrogen for 10 minutes, freeze it and vacuum After freeze-drying for 60 hours, a vegetable protein airgel is obtained.

Example 8

Calcium hydroxide and sodium hydroxide are mixed at a weight ratio of 1:1 to prepare a lye with a pH of 10, and a cross-linking agent aqueous solution with a molecular molar concentration of 0.008mol/mL is prepared using gluconolactone, and the wheat gluten powder 1. Mix pea protein powder at a ratio of 1:1 and set aside; take 39 parts of the mixture of wheat protein powder and pea protein powder, mix 201 parts of boiler condensate water, and mix 60 parts of lye into a 0.5-ton reactor, control the temperature at 85°C, and stir for 40 minutes Obtain protein glue; add 33 parts of cross-linking agent aqueous solution to the glue, and stir for 50 minutes, then pour into the mold, and stand at a temperature of 10°C for 40 hours to form a gel; submerge the whole piece of gel in an equal volume of distilled water at room temperature Replacement for 8 hours, 5 times in a row; immerse the gel after replacement with distilled water in liquid nitrogen for 10 minutes, freeze and dry it in vacuum for 50 hours to obtain a soybean protein aerogel.

The plant protein airgel described in Examples 1-8 has an apparent density of 0.15-0.2 g/cm ³ , a specific surface area of 110-130 m ² /g, is rich in mesopores, and can be used as an adsorption or thermal insulation material. The raw materials in the preparation process of the vegetable protein airgel of the present invention are easy to obtain, low in cost and environmentally friendly; the preparation process is simple, the cycle is short, and the safety is high.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (8)

1. A kind of 1. vegetable protein aeroge, it is characterised in that：Described 0.15 ~ 0.2g/cm of vegetable protein aeroge apparent density³, 110 ~ 130m of specific surface area²/ g, rich in mesoporous；Its preparation method comprises the following steps that：

   1）Plant protein powder, alkali lye and water are put into reactor, albumen glue is obtained after hydrothermal treatment；

   2）Cross-linking agent aqueous solution is added to step 1）Albumen glue in, stir 15 ~ 50min, then pour into mould stand 2 ~ 48h forms gel, and dwell temperature is 10 ~ 40 DEG C；

   3）Step 2）Gel through replace Solvent exchange drying, using 5 ~ 10min of liquid nitrogen frozen, vacuum freeze drying 24 ~ 72h systems Obtain vegetable protein aeroge.
2. 2. vegetable protein aeroge according to claim 1, it is characterised in that：Step 1）The pH value of the alkali lye be 9 ~ 13, step 2）The molar concentration of cross-linker molecules is 0.0003 ~ 0.012mol/mL in described cross-linking agent aqueous solution.
3. 3. vegetable protein aeroge according to claim 1 or 2, it is characterised in that：Plant protein powder, alkali lye, water, crosslinking The weight ratio of the agent aqueous solution is：30~50:120~400:30~100:21~38.
4. 4. vegetable protein aeroge according to claim 1 or 2, it is characterised in that：Step 1）In, described vegetable protein Powder is one in defatted soy flour, soybean separation protein white powder, peanut protein powder, gluten powder, Fed Protein Powder of Pea Insteal, corn protein powder Kind or several mixtures；Described water is distilled water or boiler blow-down water；Described alkali lye is sodium hydrate aqueous solution, hydrogen-oxygen Change one or more of mixtures in the calcium aqueous solution, ammoniacal liquor.
5. 5. vegetable protein aeroge according to claim 1 or 2, it is characterised in that：Step 2）In, described crosslinking agent is One or more of mixtures in calcium chloride, gluconic acid lactone, formaldehyde, acetaldehyde, glyoxal, glutaraldehyde.
6. 6. vegetable protein aeroge according to claim 1 or 2, it is characterised in that：Step 3）Described in displacement solvent For one or more of mixtures in water, absolute ethyl alcohol, acetone, n-hexane.
7. 7. vegetable protein aeroge according to claim 1 or 2, it is characterised in that：Step 1）Described in hydro-thermal process Specially：Temperature is 65 ~ 95 DEG C, mixes 30 ~ 60min.
8. 8. vegetable protein aeroge according to claim 1 or 2, it is characterised in that：Step 3）Described in replacement Treatment Specially：1 displacement solvent is changed every 8h, is continuously changed 3 ~ 8 times, the volume ratio of 1 displacement solvent and gel is 1:1.