Thermochemical conversion of poultry chicken feather fibers of different colors into microporous fibers

• Carbon-nitrogen fibers were derived from the waste of poultry chicken feathers.
• Thermal behavior of poultry chicken feather fibers varied depending on their color.
• The role of color on chicken feather fiber char characteristics was investigated.

Thermochemical behavior of the poultry chicken feather fibers (PCFFs) of different colors was studied to gain an insight into their structural changes that were considered when converting them into fibers through pyrolysis process. PCFFs collected from different local farms were categorized according to their color as black, white, and brown. UV light spectroscopy examination revealed that the brown PCFFs were the richest of all in the amount of extractable keratin. Glass transition, melting, and thermal decomposition temperatures of the PCFFs were measured to form the scientific basis for evaluation of the pyrolysis steps. It was revealed that, regardless of color, duration of the heat treatment applied during pyrolysis of the PCFFs at any temperatures below their own crystalline melting peak temperature posed a significant influence on the extent of cleavage of disulfide bonds and the degree of the intermolecular crosslinking achieved. Based on the thermal findings obtained, a-two step pyrolysis method was used to produce the fibers. Scanning electron microscopy (SEM) examination showed that all the resulting fibers were free of etching and preserved their stringy appearance and smoothness when the first and the second steps of pyrolysis were carried out at 230 °C for 24 h and at 450 °C for 1 h, respectively. X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) determinations revealed that the structural changes in the PCFFs subsequent to pyrolysis vary to some extent according to their color. Elemental composition and the specific surface area of the PCFFs were also measured. It was determined that all of the PCFFs after pyrolysis turned into nitrogen containing microporous carbonaceous materials with different oxygen functionalities and surface areas, depending on their color.