Effect of formic acid exposure on keratin fiber derived from poultry feather biomass

Converting poultry feather biomass into useful products presents a new avenue of utilization of agricultural waste material. However, not much is understood about the poultry feather structure or methods to process it. In this study, formic acid vapor is systematically allowed to penetrate the feather fiber structure, which is composed of keratin. The diffusion kinetics show Fickian behavior during absorption. After very long times, i.e., greater than 103 h, the absorption experiments are stopped and the formic acid is allowed to desorb from the keratin material. The desorption kinetics of formic acid out of the keratin fiber do not mirror the absorption kinetics, indicating a change in the keratin microstructure. DSC and NMR spectroscopy analyses on the keratin fiber show a reduction in the area of the crystalline melting peak and solubilization of amino acids upon formic acid exposure. This indicates that the crystallinity is disrupted resulting in more amorphous fraction in the keratin polymer.