METHOD FOR PREPARING CHITOSAN AND DERIVATIVE NANOFIBER THEREOF BY MECHANICAL MEANS

Abstract

The invention discloses a method for preparing chitosan and a derivative nanofiber thereof by mechanical means. The method comprises: firstly pre-treating a chitosan fiber or a chitosan derivative fiber material (referred to as chitosan fiber) of a suitable length with water or alkali or acid of an appropriate concentration added, then refining or beating the treated fiber (preferably using a beating device in a beating and papermaking process) to obtain a micro-sized chitosan fiber, and finally homogenizing the micro-sized chitosan fiber under a high pressure to obtain a chitosan nanofiber. According to an electron microscope image, the obtained chitosan nanofiber reaches a nano-level. The method is simple in operation and convenient for industrial production, and the obtained chitosan nanofiber with a new topology has broad application prospects in biomedicine, daily chemical engineering and special materials.

Claims

1. A method for preparing chitosan and a derivative nanofiber thereof by mechanical means, characterized in that, the method comprises the following steps: (1) cutting a fiber material, and then soaking the fiber material in deionized water or pre-treating the fiber material with dilute alkali or dilute acid, wherein the fiber material is a chitosan fiber or a chitosan derivative fiber; (2) performing preliminary mechanical treatment on the pre-treated fiber material in the step (1) by a refining or beating device to obtain a micro-sized fiber pulp; (3) putting the micro-sized fiber pulp obtained in the step (2) into deionized water, and defibering and diluting the micro-sized fiber pulp into a fiber turbid liquid by a fluffer; and (4) homogenizing the fiber turbid liquid prepared in the step (3) in a high-pressure homogenizer to prepare a chitosan nanofiber emulsion.

2. The method according to claim 1, characterized in that, a fiber length of the fiber material after cutting in the step (1) is less than 30 mm; and a mass concentration of the dilute acid or the dilute alkali is 0.05 wt % to 10 wt %.

3. The method according to claim 1, characterized in that, the refining or beating device in the step (2) is a mechanical treatment device for finely fiberizing the fiber material.

4. The method according to claim 3, characterized in that, the mechanical treatment device is a continuous beating device in a papermaking process, which is a disc refiner, a conical refiner or a cylindrical refiner.

5. The method according to claim 3, characterized in that, the mechanical treatment device further comprises an intermittent beating device, which is a trough beater.

6. The method according to claim 1, characterized in that, a mass concentration of the fiber turbid liquid in the step (3) is 0.01 wt % to 1 wt %.

7. The method according to claim 1, characterized in that, the high-pressure homogenizer in the step (4) is a nano homogenizer.

8. The method according to claim 7, characterized in that, the nano homogenizer is a high-pressure micro-jet nano disperser MINI or an ultrahigh-pressure nano homogenizer Nano DeBEE.

9. The method according to claim 1, characterized in that, when a size of the fiber material after cutting is less than 1 mm, the fiber after being dispersed with water is directly subjected to the treatment of the step (3) without going through the treatment of the step (1) and the treatment of the step (2).

10. The method according to claim 1, characterized in that, the homogenizing in the step (4) is performed for 5 times to 40 times; and an operating temperature is 10° C. to 60° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a TEM image of a chitosan nanofiber prepared in Embodiment 1.

[0024] FIG. 2 is a TEM image of a chitosan nanofiber prepared in Embodiment 3.

[0025] FIG. 3 is a TEM image of a chitosan nanofiber prepared in Embodiment 5.

DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention is further described in detail hereinafter with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited to this. It should be noted that the following processes, if not specifically described in detail, can be realized or understood by those skilled in the art with reference to the prior art.

Embodiment 1

[0027] 30 g of chitosan fibers were cut into a length of 1 mm to 3 mm first, and put into deionized water to fully absorb water and swell for 8 hours, and then pulp was poured into a filter screen and kneaded to remove water. The dewatered pulp was stood to balance a moisture for 2 hours, and a water content of the pulp after moisture balancing was measured. A dryness of the pulp was adjusted to be 10 wt %, and beating treatment was performed on the pulp with a PFI refiner for 50,000 revolutions. The beated pulp fibers were put into deionized water to disperse into a pulp suspension with a concentration of 0.3 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 5 times. FIG. 1 is a TEM image of the chitosan nanofiber in Embodiment 1 (wherein a, b and c correspond to different magnification scales). It can be seen from FIG. 1 that a diameter of the chitosan nanofiber reaches a nano-level in a projection electron microscope image of the treated chitosan fiber.

Embodiment 2

[0028] 30 g of chitosan derivative fibers were cut into a length of 30 mm first, and put into a 10 wt % alkaline solution to soak for 1 hour, and then pulp was poured into a filter screen and washed with water for many times until a washing liquor was alkalescent. Water was removed through squeezing, the dewatered pulp was stood to balance a moisture for 2 hours, and a water content of the pulp after moisture balancing was measured. A dryness of the pulp was adjusted to be 10 wt %, and beating treatment was performed on the pulp with a PFI refiner for 80,000 revolutions. The beated pulp fibers were put into deionized water to disperse into a pulp suspension with a concentration of 0.01 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 40 times. A diameter of the chitosan nanofiber also reached a nano-level.

Embodiment 3

[0029] 30 g of chitosan fibers were cut into a length of 3 mm to 5 mm first, and put into a 0.05 wt % acid solution to soak for 0.5 hour, and then pulp was poured into a filter screen and washed with water for many times until a washing liquor was weakly acidic. Water was removed through squeezing, the dewatered pulp was stood to balance a moisture for 2 hours, and a water content of the pulp after moisture balancing was measured. A dryness of the pulp was adjusted to be 10 wt %, and beating treatment was performed on the pulp with a cylindrical refiner for 50,000 revolutions. The beated pulp fibers were put into deionized water to disperse into a pulp suspension with a concentration of 1 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 20 times. As shown in FIG. 2, a diameter of the chitosan nanofiber also reached a nano-level.

Embodiment 4

[0030] 30 g of chitosan fibers were cut into a length of 10 mm to 15 mm first, and put into a 0.1 wt % acid solution to soak for 0.5 hour, and then pulp was poured into a filter screen and washed with water for many times until a washing liquor was weakly acidic. Water was removed through squeezing, the dewatered pulp was stood to balance a moisture for 2 hours, and a water content of the pulp after moisture balancing was measured. A dryness of the pulp was adjusted to be 10 wt %, and beating treatment was performed on the pulp with a cylindrical refiner for 80,000 revolutions. The beated pulp fibers were put into deionized water to disperse into a pulp suspension with a concentration of 0.5 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 25 times. A diameter of the chitosan nanofiber also reached a nano-level.

Embodiment 5

[0031] 30 g of chitosan fibers were cut into a length of 15 mm to 20 mm first, and put into 5 wt % alkaline solution to soak for 2 hours, and then pulp was poured into a filter screen and washed with water for many times until a washing liquor was alkalescent. Water was removed through squeezing, the dewatered pulp was stood to balance a moisture for 2 hours, and a water content of the pulp after moisture balancing was measured. A dryness of the pulp was adjusted to be 10 wt %, and beating treatment was performed on the pulp with a conical refiner for 100,000 revolutions. The beated pulp fibers were put into deionized water to disperse into a pulp suspension with a concentration of 0.1 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 20 times. As shown in FIG. 3, a diameter of the chitosan nanofiber also reached a nano-level.

Embodiment 6

[0032] 30 g of chitosan fibers were cut into a length of 3 mm to 5 mm first, and put into deionized water to fully absorb water and swell for 8 hours, and then pulp was poured into a filter screen and kneaded to remove water. The dewatered pulp was stood to balance a moisture for 2 hours, and a water content of the pulp after moisture balancing was measured. A dryness of the pulp was adjusted to be 10 wt %, and beating treatment was performed on the pulp with a conical refiner for 100,000 revolutions. The beated pulp fibers were put into deionized water to disperse into a pulp suspension with a concentration of 0.03 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 10 times. A diameter of the chitosan nanofiber also reached a nano-level.

Embodiment 7

[0033] 1 g of chitosan fibers with a length less than 1 mm were put into deionized water to disperse into a pulp suspension with a concentration of 0.03 wt %. The suspension was put into a fluffer for defibering, so that the fibers were evenly dispersed in water. The evenly dispersed fiber turbid liquid was poured into a homogenizer for homogenizing, and a chitosan nanofiber emulsion could be obtained after homogenizing for 30 times. A diameter of the chitosan nanofiber also reached a nano-level.