Process and hydrogen bonding mechanism of keratin dissolution in weakly alkaline eutectic solvent
A method for dissolving and extracting keratin with little damage from chicken feathers was established by using the strong hydrogen bond dissolving ability of low eutectic solvent(DES)and the efficient disulfide bond breaking ability of reducing agent and DES.13 DES in three types(basic,neutral and acidic)were designed and synthesized using choline chloride as hydrogen bond acceptor(HBA),ethanolamine,ethylene glycol,lactic acid and so on as hydrogen bond donors(HBD),and the influence of reducing agent content(based on the mass of chicken feathers,the same below),temperature,water mass fraction in DES on the relative molecular mass and extraction rate of keratin were investigated.The hydrogen bond network structure in DES was analyzed by density functional theory(DFT)and solvent polarity parameters,and the dissolution mechanism of DES on chicken feather keratin with weak loss was studied.The results showed that under the optimal extraction process of using ethanolamine as HBD without reducing agent added,n(ethanolamine)∶n(choline chloride)=2∶1,temperature 65℃,no water in DES and extraction time of 0.5 h,regenerated keratin exhibited an extraction yield of 31.8%and the highest relative molecular mass of up to 66000.The DES prepared with ethanolamine as HBD displayed reducibility,and as basic DES,it showed large internal hydrogen bond number,small hydrogen bond action and low hydrogen bond energy,which could disrupt the hydrogen bond network inside the chicken feathers without causing too much damage to the secondary structure of the chicken feathers.
deep eutectic solventskeratindissolution mechanismmolecular simulationhydrogen bondsseparation and purification technology
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