Extraction Of Wool Kraft Protein And Study On Adsorption Of Copper Ion On Keratin Films

Keratin is the main element of the wool and one of the important sources of renewable protein. Extraction of wool keratin is one of the important ways to solve the shortage and waste of resources.In this paper, keratin was extracted by NaHSO3 and TCEP methods, respectively. The structure and properties of NaHSO3-extracted keratin and TCEP-extracted keratin were studied. The results showed that both TCEP and NaHSO3 had a strong damage on disulfide bond of wool and then keratin was extracted. For the NaHSO3 method, the reversible reaction between NaHSO3 and cystine limits the ability of open disulfide bond in extraction. The protein dissolution rate and extraction yield of NaHS03 method was relatively low and molecular weight distribution of extracted keratin was wide. For the TCEP method, extraction yield is higher and molecular weight distribution is relatively concentrated which is associated with the high dissolving efficiency and break key ability of TCEP method. Although the keratin extracted by NaHSO3 and TCEP methods is belong to protein, their molecular structure, element composition, thermodynamic properties was different which is maybe related with the participation of P element in the process of TCEP extracted wool.keratin extrated by TCEP method was analyzed through XPS and TG. The results showed that the structure of the extracted lower level keratin is mainly P=S and O=P and the structure of extracted upper level keratin is RSH. Compared with the extracted upper level keratin, the extracted lower level keratin has relatively higher decomposition temperature and slightly lower molecular weight,TCEP-extracted keratin/PVA film was made and the adsorption of heavy metal copper was studied. The keratin extracted by TCEP had active. Keratin and PVA had good compatibility and the surface of composite membrane relatively smooth. With the increase of the content of protein in the TCEP-extracted keratin/PVA film, hydrogen bonding between keratin and PVA was enhanced and then become weak. The TCEP-extracted keratin/PVA film had good adsorption capacity for copper ions and the maximum adsorption capacity for copper ion could reach 55.6 mg/g.