Method for preparing low-molecular weight chitosan by using impulse electric field

A technology of pulsed electric field and low molecular weight, which is applied in the field of preparation of low molecular weight chitosan by high-intensity pulsed electric field, can solve the problems that are not conducive to continuous production, toxic and harmful substances, and acid residues need to be treated, so as to reduce cleaning and sewage The effect of governance and low energy consumption

Inactive Publication Date: 2011-05-11
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 1) Irradiation degradation requires high equipment and may produce toxic and harmful substances.
[0006] 2) The preparation of low molecular weight chitosan by microwave radiation is a batch operation, which is not conducive to continuous production
[0007] 3) The chemical degradation method has many disadvantages such as high cost, low output, and the need to deal with the acid residue;
[0008] 4) The enzymatic degradation method also has problems such as the high cost of the enzyme used for degradation, the complexity of the fermentation process, and the impossibility of mass industrial production.
But these patented technologies are not related to the method of preparing low molecular weight chitosan by using strong pulsed electric field treatment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] The high molecular weight chitosan (viscosity average molecular weight M η =3.0×10 5 g / mol, degree of deacetylation greater than 90%) is uniformly mixed with an aqueous solution containing acetic acid, wherein the mass concentration of chitosan is 1% and the mass concentration of acetic acid is 3%. The chitosan solution was pumped into the pulsed electric field device with a continuous constant current pump, while adjusting the electric field strength to 40kV / cm, pulse width 10μs, pulse frequency 1000Hz, pulse waveform to square wave, and pulse processing time to 10ms. Add 0.5 mol / L sodium hydroxide solution to the pulsed chitosan solution, adjust the pH to 6.0, stand for precipitation, and centrifuge to obtain a precipitate. The precipitate was washed twice with acetone and dried in vacuum to obtain low molecular weight chitosan (viscosity average molecular weight M η =2.3×10 4 g / mol, yield 85%).

Embodiment 2

[0030] The high molecular weight chitosan (viscosity average molecular weight M η =6.8×10 5 g / mol, deacetylation degree greater than 80%) is mixed uniformly with an aqueous solution containing hydrogen peroxide, wherein the mass concentration of chitosan is 10%, and the mass concentration of hydrogen peroxide is 15%. The chitosan solution was pumped into the pulsed electric field device with a continuous constant current pump, while adjusting the electric field strength to 50kV / cm, pulse width 50μs, pulse frequency 100Hz, pulse waveform to square wave, and pulse processing time to 200ms. Add a mixed solution containing 1.0 mol / L sodium bicarbonate and 0.5 mol / L potassium hydroxide to the pulse-treated chitosan solution, adjust the pH to 7.2, stand for precipitation, and centrifuge to obtain a precipitate. The precipitate was washed 3 times with ether and dried in vacuum to obtain low molecular weight chitosan (viscosity average molecular weight M η =1.6×10 4 g / mol, yield 85%)....

Embodiment 3

[0032] The high molecular weight chitosan (viscosity average molecular weight M η =4.5×10 5 g / mol, deacetylation degree greater than 70%) is mixed uniformly with an aqueous solution containing formic acid and lactic acid, wherein the mass concentration of chitosan is 7%, the mass concentration of formic acid is 8%, and the mass concentration of lactic acid is 12%. The chitosan solution was pumped into the pulsed electric field device with a continuous constant current pump, while adjusting the electric field strength to 45kV / cm, pulse width 80μs, pulse frequency 500Hz, pulse waveform to square wave, and pulse processing time to 300ms. Add 2.0 mol / L sodium hydroxide solution to the pulsed chitosan solution, adjust the pH to 6.8, stand for precipitation, and centrifuge to obtain a precipitate. The precipitate was washed twice with ether and dried in vacuum to obtain low molecular weight chitosan (viscosity average molecular weight M η =1.7×10 4 g / mol, yield 88%).

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Abstract

The invention discloses a method for preparing low-molecular weight chitosan by utilizing pulsed electric field. The method takes high-molecular weight chitosan with molecular weight more than 2.5*10<5>g / mol as the raw material and utilizes pulsed electric field to prepare low-molecular weight chitosan with low-molecular weight less than 2.3*10<4>g / mol. The method comprises the following steps: high-molecular weight chitosan dissolution, pulsed electric field treatment, lye pH adjustment, sedimentation, centrifugation, abstersion and drying, thus obtaining the low-molecular weight chitosan. The pulsed electric field treatment is to treat chitosan solution in a pulsed electric field processor; the electric field strength is 40 to 60kV / cm, the pulse width is 10 to 100mus, the pulse frequency is 100 to 1,000Hz, the pulse waveform is square wave and the period for treating chitosan in the pulsed electric field is 1 to 1,000ms. The preparation method provided by the invention has the advantages of simplicity and feasibility, short electric field treatment period, strong practicality, energy saving and environment protection and easy popularization.

Description

Technical field [0001] The invention relates to a method for preparing low molecular weight chitosan, in particular to a method for preparing low molecular weight chitosan by adopting high-strength pulsed electric field treatment. Background technique [0002] Chitosan is the product of partial or complete deacetylation of chitin, and its molecular chain consists of β-(1-4)-2-acetamido-D-glucose units and β-(1-4)-2-amino -Copolymer composed of D-glucose units. The chitosan molecule contains active amino groups, which can be positively charged and is the only natural alkaline polysaccharide. There are active hydroxyl groups on the sugar ring, so chitosan has good hydrophilicity and water retention. [0003] Chitosan has a variety of biologically active functions such as antibacterial, lowering cholesterol, lowering blood lipids, enhancing immune function, and anti-tumor function. It is widely used in food, biology, medicine, agriculture, environment, materials and other industries...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J3/28C08L5/08
Inventor 曾新安韩忠于淑娟扶雄张本山
Owner SOUTH CHINA UNIV OF TECH
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