A one-pot method for preparing nano-chitin using a eutectic solvent

Abstract

This application discloses a one-pot method for preparing nano-chitosan using a eutectic solvent, comprising the following steps: mixing oven-dried marine waste powder with a eutectic solvent, reacting, adding a mixed solution of alcohol and water, precipitating, centrifuging, separating the resulting solid, diluting, dialysis, centrifuging, and separating again to obtain upper chitosan nanowhiskers (ChNC) and lower chitosan nanocrystal bundles (ChSR). This method simultaneously recovers chitosan nanowhiskers (ChNC) and ChSR (chitosan solid residue), and homogenizes the ChSR to obtain chitosan nanofibers, minimizing chitosan loss and maximizing total yield. The prepared chitosan nanowhiskers and chitosan nanofibers can be applied to polymer reinforcement, food packaging, water treatment, and drug delivery, among other applications.

Description

Technical Field

[0001] This application relates to a one-pot method for preparing nano-chitin using a eutectic solvent, which belongs to the field of nanomaterial preparation. Background Technology

[0002] The concept of eutectic solvents (DES) was first proposed by Abbot in 2003. DES are typically low-melting-point mixtures formed by hydrogen bonding between hydrogen bond acceptors (HBAs) such as quaternary ammonium salts and quaternary salts, and hydrogen bond donors (HBDs) such as amides, carboxylic acids, and alcohols in a certain proportion. DES not only possesses the advantages of ionic liquids but also exhibits unique properties such as low cost, ease of preparation, biodegradability, and good biocompatibility. Nano-chitin, as a highly promising nanomaterial, not only retains the characteristics of original chitin but also possesses a high aspect ratio, high specific surface area, low density, and abundant functional groups, which is beneficial for surface functionalization and has wide applications in biomedicine, food industry, water treatment, green electronics, cosmetics, and other fields. The one-pot method for preparing nano-chitin using eutectic solvents simultaneously amplifies the advantages of both, thereby…

[0003] Currently, methods for preparing nano-chitosan include acid hydrolysis, mechanical treatment, and TEMPO oxidation. Some methods involving acids produce environmentally harmful byproducts. Summary of the Invention

[0004] The eutectic solvent one-pot method used in this application prepares nano-chitosan, simultaneously recovering chitosan nanocrystals and ChSR (chitosan solid residue) to minimize chitosan loss and maximize overall yield. The eutectic solvent preparation method generates no harmful waste liquid / gas, making it environmentally friendly.

[0005] This invention provides a one-pot method for preparing nano-chitosan using a eutectic solvent. This application utilizes a series of eutectic solvents to reduce chitosan to the nanoscale under specific temperature, time, and mass ratio conditions. The eutectic solvent is selected from one of the following: choline chloride, betaine, or proline, which are respectively heated and mixed with oxalic acid, ethylene glycol, glycerol, or benzenesulfonic acid.

[0006] According to one aspect of this application, a method for preparing nano-chitosan using a one-pot eutectic solvent is provided, characterized in that...

[0007] Includes the following steps:

[0008] The oven-dried marine waste powder was mixed with a eutectic solvent and reacted. Then, a mixture of alcohol and water was added, and the mixture was precipitated, centrifuged, and the resulting solid was diluted, dialyzed, centrifuged, and separated to obtain the upper chitin nanofibers (ChNC) and the lower chitin nanofiber bundles (ChSR).

[0009] Specifically, the following steps are included:

[0010] a) Marine waste powder reacts with various eutectic solvents under certain conditions to obtain suspension I;

[0011] b) Add the suspension I to an alcohol / water solution and centrifuge to obtain suspension II;

[0012] c) The suspension II is separated to obtain waste liquid I and solid I;

[0013] d) After diluting the solid I to a certain concentration, dialyze and centrifuge to obtain suspension III;

[0014] e) After separating and processing the suspension III, an upper layer of chitin nanocrystals (ChNC) and a lower layer of waste liquid solid (CSR) are obtained;

[0015] The eutectic solvent is obtained through the following steps:

[0016] Substance A and substance B are mixed and heated to obtain the eutectic solvent;

[0017] Substance A is selected from at least one of choline chloride, betaine, and proline;

[0018] The substance B is selected from at least one of oxalic acid, ethylene glycol, glycerol, p-toluenesulfonic acid, and benzenesulfonic acid.

[0019] The mass ratio of the absolutely dry marine waste powder to the eutectic solvent is 5 to 15:1;

[0020] The reaction temperature is 90–130°C;

[0021] The reaction time is 2 to 4 hours.

[0022] The centrifuge speed is 5000-15000 rpm;

[0023] The centrifugation time is 2 to 4 minutes.

[0024] The dialysis conditions were: 24 hours, 3 water changes.

[0025] The chitin nanomaterials obtained by the above preparation method can be applied in the fields of biomedicine, chemical industry, food industry, agriculture and microelectronics.

[0026] The beneficial effects that this application can produce include:

[0027] 1) This application successfully prepared nano-chitosan using a one-pot method with a eutectic solvent.

[0028] 2) This application achieves the simultaneous recovery of chitin nanocrystals ChNC and ChSR (chitin solid residue), and obtains chitin nanofibers by homogenizing ChSR, so as to minimize chitin loss and increase the total yield.

[0029] 3) The chitin nanocrystals and chitin nanofibers prepared in this application can be used in polymer reinforcement, food packaging, water treatment and drug delivery, etc. Attached Figure Description

[0030] Figure 1 This is a transmission electron microscope image of chitin nanocrystals in Example 1 of this application, with a scale of 0.5 μm;

[0031] Figure 2 This is a scanning electron microscope image of chitin nanocrystals in Example 1 of this application, with a scale of 1 μm. Detailed Implementation

[0032] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0033] This application describes the transmission electron microscopy and scanning electron microscopy tests performed on the prepared chitin nanomaterials.

[0034] The transmission electron microscopy (TEM) testing conditions were as follows: the morphology and size distribution of the samples were characterized using TEM, and the sample preparation method was the same as that used for SEM testing of samples in aqueous phase. The diameters of 150 particles in the TEM images were measured, and the particle size distribution of the nano-chitosan was statistically analyzed using software.

[0035] The scanning electron microscope (SEM) testing conditions were as follows: The morphology of the sample was observed using a scanning electron microscope in GB mode with an accelerating voltage of 3.0 kV. A certain amount of sample suspension was taken, and the deionized water was replaced with anhydrous ethanol. A disposable dropper was then used to apply the sample solution to the surface of a 300-mesh carbon-coated copper mesh. The copper mesh was dried under an infrared lamp, and the sample loaded on the copper mesh surface was characterized.

[0036] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0037] Example 1

[0038] This embodiment provides a one-pot method for preparing nano-chitosan using a eutectic solvent. The preparation process steps are as follows:

[0039] (1) The eutectic solvent formed by heating and mixing choline chloride and oxalic acid was reacted with the dry marine waste powder at a temperature of 130°C for 3 hours and with masses of 10g of eutectic solvent and 1g of dry marine waste powder.

[0040] (2) Then the reactants were placed in a 200ml mixture of alcohol and water in a ratio of 7:3 to precipitate.

[0041] (3) Centrifuge the mixture at 10,000 rpm for 3 min to obtain the upper waste liquid and the lower solid.

[0042] (4) After adding 100ml of deionized water to the lower solid layer, transfer it to a dialysis bag for dialysis for 24 hours, changing the water every 8 hours during this period.

[0043] (5) After dialysis, centrifuge again at 10,000 rpm for 3 min to obtain the upper chitin nanocrystals (ChNC) and the lower waste liquid solid (ChSR).

[0044] Example 2

[0045] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and oxalic acid, respectively, at 100°C.

[0046] Example 3

[0047] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are proline and oxalic acid, respectively, at 100°C.

[0048] Example 4

[0049] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are choline chloride and oxalic acid, respectively, at 130°C.

[0050] Example 5

[0051] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and oxalic acid, respectively, at 130°C.

[0052] Example 6

[0053] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are proline and oxalic acid, respectively, at 130°C.

[0054] Example 7

[0055] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are choline chloride and glycerol, respectively, at 100°C.

[0056] Example 8

[0057] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are choline chloride and glycerol, respectively, at 130°C.

[0058] Example 9

[0059] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and glycerol, respectively, at 100°C.

[0060] Example 10

[0061] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are betaine and glycerol, respectively, at 130°C.

[0062] Example 11

[0063] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are proline and glycerol, respectively, at 100°C.

[0064] Example 12

[0065] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are proline and glycerol, respectively, at 130°C.

[0066] Example 13

[0067] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are choline chloride and benzenesulfonic acid, respectively, at 100°C.

[0068] Example 14

[0069] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are choline chloride and benzenesulfonic acid, respectively, at 130°C.

[0070] Example 15

[0071] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and benzenesulfonic acid, respectively, at 100°C.

[0072] Example 16

[0073] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and benzenesulfonic acid, respectively, at 130°C.

[0074] Example 17

[0075] The specific operation is the same as in Example 1, except that the eutectic solvent and heating temperature are proline and benzenesulfonic acid, respectively, at 100°C.

[0076] Example 18

[0077] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are proline and benzenesulfonic acid, respectively, at 130°C.

[0078] Example 19

[0079] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are choline chloride and ethylene glycol, respectively, at 100°C.

[0080] Example 20

[0081] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are choline chloride and ethylene glycol, respectively, at 130°C.

[0082] Example 21

[0083] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and ethylene glycol, respectively, at 100°C.

[0084] Example 22

[0085] The specific operation is the same as in Example 1, except for the eutectic solvent and the heating temperature, which are betaine and ethylene glycol, respectively, at 130°C.

[0086] Example 23

[0087] The specific operation is the same as in Example 1, except that the eutectic solvent and heating temperature are proline and ethylene glycol, respectively, at 100°C.

[0088] Example 24

[0089] The specific operation is the same as in Example 1, except for the eutectic solvent and heating temperature, which are proline and ethylene glycol, respectively, at 130°C.

[0090] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing nano-chitin using a one-pot eutectic solvent, characterized in that, Includes the following steps: The oven-dried marine waste powder was mixed with a eutectic solvent and reacted. Then, a mixture of alcohol and water was added, and the mixture was precipitated, centrifuged, and the resulting solid was diluted, dialyzed, centrifuged, and separated to obtain the upper chitin nanofibers (ChNC) and the lower chitin nanofiber bundles (ChSR).

2. The preparation method according to claim 1, characterized in that, The eutectic solvent is obtained through the following steps: Substance A and substance B are mixed and heated to obtain the eutectic solvent; Substance A is selected from at least one of choline chloride, betaine, and proline; The substance B is selected from at least one of oxalic acid, ethylene glycol, glycerol, p-toluenesulfonic acid, and benzenesulfonic acid.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the absolutely dry marine waste powder to the eutectic solvent is 5 to 15:1; The reaction temperature is 90–130°C; The reaction time is 2 to 4 hours.

4. The preparation method according to claim 1, characterized in that, The centrifuge speed is 5000-15000 rpm; The centrifugation time is 2 to 4 minutes.

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