Extraction, Purification And Characterization Of Wool Keratin

Keratin is a kind of natural polymer with broad application prospects.It is abundant in animal tissues such as hair,nails,horns and hooves.Wool is an important source of keratin,which contains more than 80% of keratin.However,a large amount of waste wool resources is landfilled or burned every year,which causes waste of resources and environmental pollution.And at present,most of the researches on keratin extraction and applying to high value-added products is at the experimental stage.Therefore,it is of great significance to explore keratin extraction methods that are industrially viable and environmentally friendly.Based on summarizing relevant researches and the requirements of industrialization and green process,this study explored the process of extracting wool keratin by molten urea method and characterized the basic properties of extracted keratin.Then Response Surface Methodology was used to optimize the processes of isoelectric point method and salting out method,and a viable extraction method was obtained.According to the results,the optimum process of the molten urea method is: bath ratio 1:7.5,dissolution time 90 min,and dissolution temperature 140°C.The dissolution ratio of wool fiber reaches 86.17%,and the extraction ratio of wool keratin is about 66.95% under the conditions.The molecular weight of the obtained keratin is from 5 to 10 kDa,and the macromolecular backbone and crystal structure are damaged to some extent,but the ?-helix structure and the ?-sheet structure are retained to a certain extent.Optimized through the Response Surface Methodology,the extraction ratios of keratin of the isoelectric point method and the salting out method are respectively 24.05% ± 0.76% and 28.82% ± 0.96%,while the extraction ratio of keratin of the combination of the two methods is 57.90%.± 0.83%,which is higher than the sum of keratin extraction ratios when the two methods are used alone.The extraction process of keratin in this study has the characteristic of environmental protection.The wastewater of this method can be used in the fertilizer industry,which can reduce the treatment cost.The molten urea method can be further extended to the extraction of keratin from other materials,which has wide application range and practical value.